As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared w...As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.展开更多
Soil seed banks can provide a mechanistic for understanding the recruitment dynamics and can inform conservation management of ecosystems. To investigate the contribution of soil seed banks to vegetation restoration i...Soil seed banks can provide a mechanistic for understanding the recruitment dynamics and can inform conservation management of ecosystems. To investigate the contribution of soil seed banks to vegetation restoration in moving sand dune systems, we compared seed structure and species similarity between soil seed banks and standing vegetation among moving sand dunes, ecotones and dune slacks in northeast China. Average seed density in dune slacks was greater than in ecotones or moving sand dunes. Seed density in the soil layer of 0-10 cm was greater than at 10-20 cm both in the moving sand dunes and the eco- tones, but seed densities were similar at depths of 10-20 and 20-30 cm in moving sand dunes. Moreover, the spatial autocorrelation of seed density on moving sand dunes was weak but was strong on the ecotones and dune slacks. The species in the soil seed bank of moving sand dune systems were nearly all annuals, and the low similarity was mainly due to the lack of perennial species that were common in standing vegetation. Consequently, vegetation restoration cannot mainly rely on the soil seed banks in the movingsand dunes and more attention should be paid to protection of the dune slacks because they are the main source of seed disperse and seedling recruitment in moving sand dune systems.展开更多
Black locust(Robinia pseudoacacia L.)plantations have contributed significantly to soil and water conservation and ecological reconstruction on China’s Loess Plateau.Understanding the impact of stand and environment ...Black locust(Robinia pseudoacacia L.)plantations have contributed significantly to soil and water conservation and ecological reconstruction on China’s Loess Plateau.Understanding the impact of stand and environment on species composition of understory woody plants will improve the stability of existing black locust plantations.Ten stands were selected in second-generation black locust plantations in tableland and gully areas of the Loess Plateau.The number of understory tree species in the tablelands was significantly lower than in the gully stands.Regenerated black locust(19.76%)and Rubus corchorifolius L.f.(64.85%)were the most abundant understory tree and shrub species,respectively,in the tableland stands;Broussonetia papyrifera(L.)L’Hér.ex Vent.(6.77%)and Acanthopanax senticosus(Rupr.Maxim.)Harms.(37.22%)were most abundant in the gully stands.Species richness(S),Shannon diversity(H),and evenness index(J)of the understory plants were significantly lower in the tableland stands than in the gully stands.More diverse understory species and community structures occurred in the gully stands.Differences in species diversity among landform positions may be attributed to differences in soil moisture.In addition,77.57%of the variation in understory species composition was explained,among which shrub and herb coverage,stand age,leaf area index,slope and total soil phosphorus in the 10-20 cm layer were the main factors.Soil organic carbon and total potassium significantly impacted S,H and J.Considering the environmental conditions and the biological characteristics of the plants investigated,R.corchorifolius should be given priority in the development of tableland stands,while B.papyrifera and Celtis sinensis Pers.should form mixed forests with black locust in gully stands.This management could promote biodiversity and stability of the existing black locust plantations but also optimize regional landscape patterns.展开更多
Species composition,structure,regeneration,and management status of Jorgo-Wato Forest(JWF)was studied.Number of individuals,diameter at breast height(dbh)and height of woody species(dbh≥2.5 cm)were counted and measur...Species composition,structure,regeneration,and management status of Jorgo-Wato Forest(JWF)was studied.Number of individuals,diameter at breast height(dbh)and height of woody species(dbh≥2.5 cm)were counted and measured in each plot.Group discussions with local farmers residing around JWF were carried out to understand the management of the JWF.Forest structural attributes were computed using descriptive statistics;correlation was used to assess relationships between the structural variables.A total of 4313 individuals(dbh≥2.5 cm)with a density of 1477 ha-1 were recorded,the number of species and individuals decreasing with increasing dbh classes.Species with the highest Importance Value Index(IVI)were Pouteria adolfifriedericii(37.7),Syzygium guineense subsp.afromontanum(23.6),Dracaena afromontana(20.5),Chionanthus mildbraedii(15.9),and Croton macrostachyus(12.3).Overall distribution of woody plants across size classes exhibited a reverse J-pattern,suggesting a healthy population structure and good regeneration.Nevertheless,some species were not represented in smaller diameter classes,including juvenile phases,which indicate a lack of regeneration.For these species,monitoring and enrichment planting would be necessary,along with curbing illegal cutting and coffee farming in the natural forest.Management interventions in the JWF need to consider livelihood options and to respect the rights of local communities.展开更多
Polypores play a cru cial role in energy recycling and forest regeneration in forest ecosystems.The majority of them are wood degraders;some are forest pathogens and others are ectomycorrhizal symbionts.The basidiocar...Polypores play a cru cial role in energy recycling and forest regeneration in forest ecosystems.The majority of them are wood degraders;some are forest pathogens and others are ectomycorrhizal symbionts.The basidiocarps provide food and shelter for many organisms,mostly invertebrates,but also some vertebrates,as well as food and medicine for humans.Despite extensive research on the species diversity and phylogenetic relationships of polypores in recent years,there remains a lack of comprehensive understanding of their distribution patterns and species composition at the large scale.Checklists of polypores from the tropical zone,including tropical Africa,tropical America,and tropical Asia,were analyzed for species diversity,distribution patterns,major taxa,and nutritional modes.A total of 1,902 polypore species was found in the three regions,representing 8 orders,46families,and 250 genera of Agaricomycetes.The orders Polyporales(especially the family Polyporaceae)and Hymenochaetales(especially the family Hymenochaetaceae)had the most prolific taxa,with their species accounting for 93.4%of the total polypores listed.Each of 1,565(or 82.3%)of the total 1,902 species were found in only one of the three regions studied,and we treat them temporarily as"regional endemic species".Only 141species were shared among all three regions,accounting for a mere 7.4%.Tropical Africa and tropical America had the greatest number of shared species and the highest S?rensen similarity index(SC)value.Tropical forests had a higher species richness compared with temperate to boreal forests of the Northern Hemisphere,and in addition,also a higher proportion of white rot polypores compared to brown rot and ectomycorrhizal species.This study outlines the distribution patterns and species diversity of polypores in the world,shedding light on their ecological significance in diverse ecosystems.展开更多
Background:Urban remnant forests are embedded in urban areas and are threatened directly and indirectly by urbanization.The direct effects(e.g.,loss of area)have been well studied.However,knowledge about the indirect ...Background:Urban remnant forests are embedded in urban areas and are threatened directly and indirectly by urbanization.The direct effects(e.g.,loss of area)have been well studied.However,knowledge about the indirect influence of urbanization through edge effects on the biodiversity in remnant forests is limited.Methods:In this study,we surveyed woody plant species in 72 plots in nine remnant forest patches in Guiyang,China.We examined the influences of urbanization and edge effects on the species diversity and composition of woody plants in remnant forests.We compared alpha diversities and quantified compositional dissimilarities in interior and edge sites at different levels of urbanization.We also measured the niche width of the recorded plant species and assessed whether high levels of urbanization and edge effects increased the number of generalist species.Results and conclusions:The Shannon index,the Simpson index and the Pielou index of adult trees were lowest in the edge habitat under high levels of urbanization.Significant differences in the Shannon index and the Simpson index of sapling/seedling were detected between interior and edge sites under low urbanization.The edge effects on the species composition of adult trees were intensified by high levels of urbanization.Woody plant species with wide niche widths were more abundant at edge sites under high levels of urbanization.Therefore,we recommend that urban expansion surrounding remnant patches should be strictly controlled to alleviate edge effects on biodiversity.展开更多
Wetland restoration had been implemented for more than two decades in Sanjiang Plain,Northeast China.To assess the restoration effi ciency of wetland vegetation,we investigated plants composition of community,plant sp...Wetland restoration had been implemented for more than two decades in Sanjiang Plain,Northeast China.To assess the restoration effi ciency of wetland vegetation,we investigated plants composition of community,plant species diversity and aboveground biomass of restored sites in a chronosequence of restoration(1,2,3,6,8,11,15 and 25 years)in the Sanjiang Nature Reserve.As comparison,we also investigated the same factors in a cropland and a natural marsh adjacent to the restored sites.The results showed that wetland plant species can invade quickly after croplands were abandoned when there were suitable hydrology conditions.On the early stage of the restoration,weeds were main plant species in the restored sites.Wetland species appeared at the same time but diff ered from the dominant species from the adjacent natural marshes.Common native wetland species could dominance the community after 3-year restoration.Species richness and diversity increased on the early stage,and then decreased to the similar level of the natural marsh with the extension of restoration.Plant biomass could restore easier than the species composition and diversity.Our results indicated that plant species composition and diversity of abandoned reclaimed wetlands can restore gradually by natural succession in Sanjiang Plain.However,25-year restoration site had similarity index of only 56%with the natural marsh,which revealed that two decades are not enough for complete restoration of vegetation.展开更多
The study focuses on the dynamics and biomass production （g·m-2） of understory （herbaceous） plant community under broad-leaf forests consisting of Quercus leucotrichophora （Banj-oak）, Quercus floribunda （T...The study focuses on the dynamics and biomass production （g·m-2） of understory （herbaceous） plant community under broad-leaf forests consisting of Quercus leucotrichophora （Banj-oak）, Quercus floribunda （Tilonj-oak） and Quercus semicarpifolia （Kharsu-oak）, respectively in central Himalaya, India. With increasing altitudes, the den-sity and biomass decreased significantly across the three types of forests. Banj-oak forest harboured the maximum density and biomass among the other sampling sites. The mean density of herb species in two contrasting orientation differed significantly （p0.05）, showing relatively higher density on slope orientation （west）. Across the sites, total production declined significantly with increasing altitude of the sites （p0.05）, and Banj-oak forest presented the highest production.展开更多
The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversi...The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea + Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, i.e., Schefflera, Sterculia and Cleistocalyx + Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04–2.953 and 64.2%–74% respectively, but those of the Endospermum community are 4.74 and 79% respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.展开更多
Soil animal communities of Secondary forest,Platycladus forest andQuercus acutissima forest in Confucian graveyard of Qufu were investigated. 3583 specimens were collected, belonging separately to 5 Phylums, 11 Classe...Soil animal communities of Secondary forest,Platycladus forest andQuercus acutissima forest in Confucian graveyard of Qufu were investigated. 3583 specimens were collected, belonging separately to 5 Phylums, 11 Classes and 23 Orders. Two dominant groups and 9 common groups account for 94.45% of the total numbers. The soil animals in these three forest habitats differ in composition, ecological distribution and important indices. The dominant groups of soil animals in the three forests were the same, but other groups differ more greatly. Diversity index (H′) and evenness index (E) of soil animal in Secondary forest are the highest, and yet dominance index (C) inQuercus acutissima forest is the highest. Most soil animals in each forest habitats congregate to the surface soil layer. Their sorts and individual numbers are all layer I>II>III. It is very similar for composition of soil animals in the three forests.展开更多
In the last century,eucalypt plantations are increasing all over the world.Concretely,in the Basque Country(northern Iberian Peninsula),7%of pine plantations have been recently substituted by eucalypt plantations,wher...In the last century,eucalypt plantations are increasing all over the world.Concretely,in the Basque Country(northern Iberian Peninsula),7%of pine plantations have been recently substituted by eucalypt plantations,where little is known about their ecological impact on soil and plant diversity.However,the most relevant impact is due to forest management,as Eucalyptus globulus Labill.plantations have a short harvesting cycle,12–15 years rotations.In fact,the species is able to regenerate from stumps;therefore,those plantations are replanted after 3–4 rotations.This type of invasive and frequent management could lead to further adverse effects on the ecosystem.The aim of this study was to characterise and compare the eucalypt plantations newly established(New:never been harvested)with older ones(Old:several times harvested and grown from stumps),having been established for at least 35 years,and to identify the primary factors that could influence the richness and diversity of vascular plant species in those plantations.The results indicated that both plantations exhibited comparable characteristics with respect to deadwood(volume and decay stage)and tree size and density.However,the Old plantations exhibited higher forest heterogeneity,pH,and higher shrub and herb richness and diversity.Overall,generalist and invasive species were found in the New plantations,while in the Old plantations,typical species of the native forests were also observed.The factor that influenced plant diversity was the volume of deadwood.Regarding life forms,higher altitude and proximity to watercourses favoured tree diversity;and lower canopy cover,shrub diversity.In conclusion,the longer the plantation has been established,the greater the number of species that are able to survive and adapt.This is probably due to the fact that management disturbance is specific and not sufficient to remove the already established plants and the soil seed bank.展开更多
Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relative...Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 5400 stems-ha^-1 （ -〉 3.0 cm DBH）; 64% of those stems were smaller than 10 cm DBH. The total basal area was 54.4 m^2-ha^-1, of which Castanopsis sieboldii contributed 48%. The forest showed high species diversity of trees. 80 tree species （≥ 3.0 cm DBH） from 31 families was identified in the thirty sampling plots. C. sieboldii and Schima wallichii were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were, 3.36 for Diversity index （H＇）, 0.71 for Equitability index （J＇） and 4.72 for Species richness index （S＇）, all of which strongly declined with the increase of importance value of the dominant, C. sieboldii. Measures of soil nutrients indicated low fertility, extreme heterogeneity and possible A1 toxicity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil exchangeable K^＋, Ca^2＋, and Ca^2＋/Al^3- ratio （all p values 〈0.001） and a negative relationship with N, C and P. The results suggest that soil property is a major factor influencing forest composition and structure within the subtropical forest in Okinawa.展开更多
Functional traits of trees are significantly associated with their adaptation strategies and productivity.However,the effects of species composition and mixing proportion on the functional traits of trees grown in mix...Functional traits of trees are significantly associated with their adaptation strategies and productivity.However,the effects of species composition and mixing proportion on the functional traits of trees grown in mixed plantations have not been studied extensively.In this study,planting experiments(duration about seven months)were used to study variations in functional traits and biomass allocation of C unninghamia lanceolata(Lamb.)Hook and Phoebe bournei(Hemsley)Yang seedlings in five different mixes(0C:4P,1C:3P,1C:1P,3C:1P,and 4C:0P).Total leaf area per seedling increased in each species as its respective proportion in the mixture decreased.However,the specific leaf area decreased for P.bournei under low percent composition,and the specific leaf area for C.lanceolata differed only marginally among the plantings.The net photosynthetic rates of the two species were higher in the mixed plantings than in their corresponding monocultures,whereas the transpiration rate,stomatal conductance,and instantaneous water use efficiency were not different among the plantings.The average root length and root surface area of C.lanceolata and P.bournei were higher in the mixed plantings than in their monocultures.Specifically,root surface area of C.lanceolate and both root length and surface area of P.bournei increased significantly in the 1C:3P and 2C:2P mixed plantings.Leaf,stem,root,and total dry mass per seedling for C.lanceolata decreased with its increasing percent composition in the mixed plantings,while these variables varied less for P.bournei.The plasticity of biomass allocation was relatively low for both species.Total biomass per planting was higher in the mixed plantings than in the monocultures.Our study indicates that species composition and mixing proportion can considerably affect the functional traits of C.lanceolata and P.bournei.The increase in productivity in the mixed plantings may be partially attributed to low rates of competition between the two species,and future studies should examine the different interspecies relationships.The results of this study can be used to improve plantation productivity and ultimately increase the sustainability of tree products and help to better understand the adaptation strategies of plant coexistence.展开更多
In order to understand the management of regional vegetation,numerical classification and ordination are widely used to investigate community distribution and vegetation features.In particular,two-way indicator-specie...In order to understand the management of regional vegetation,numerical classification and ordination are widely used to investigate community distribution and vegetation features.In particular,two-way indicator-species analysis programs(TWINSPAN)classifies plots and species into different groups.De-trended correspondence analysis(DCA)and canonical correspondence analysis(CCA)reflects the relationship between community and site conditions.Afforestation with Larix olgensis Herry.Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains.The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process.Twenty-eight L.olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method.Species composition,community structure attributes of diversity,and site conditions were analyzed.Communities were classified by TWINSPAN into five successional stages:immature,juvenile,mid-aged,nearmature and mature.Classifications were validated by DCA and CCA analysis.Site conditions such as soil and litter thickness,soil organic matter,soil density,and pH were measured.Successional stages varied in community composition and species population,accompanied by time from afforestation and a gradient of site conditions.This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions.The study showed that L.olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.展开更多
Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forest...Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.展开更多
The structure and species composition as well as their changes in a climax forest, dominated byPinus koraiensis-Tilia amurensis andFraxinus koraiensis, were observed with an interval of 10 years. The number of tree sp...The structure and species composition as well as their changes in a climax forest, dominated byPinus koraiensis-Tilia amurensis andFraxinus koraiensis, were observed with an interval of 10 years. The number of tree species was 16 in 1981, which was kept unchanged. Density was increased from 510 to 535 stems/hm2, and basal area from 35.19 to 38.17 m2/hm2. Average stand DBH remained nearly unchanged. The total mortality of the stand was very low, 0.61% per year.Fraxinus andPinus were declining in population size, the highest mortality rate for the former, and the largest death number for the latter.Tilia showed a rapid increasing of 14.9%, and the density of saplings (DBH 3-8 cm) was 71 stems/hm2, led the top among canopy-layer species.Acer mono, similar toTilia, showed a type of continuous regeneration which was represented by the reverse J-shape of DBH distribution and compensation ability to mortality. Sub-canopy species such asAcer pseudo-sieboldianum, Maackia amurensis etc. presented a stable status by self-maintenance. Based on the fact of the decreasing of dominant populations, it is predicted that the composition of the community was changing gradually, the rising of broad-leaved components versus the declining of coniferous species.展开更多
Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, incr...Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, we studied woody plant structure, diversity and regeneration potentials in 5-and 10-year grazing exclosures in comparison with open grazed sites in a semi-arid environment. Data on species diversity, abundance, structure, basal area, frequency, density, and regeneration status were collected from 270 sample plots. Forty-one woody species representing 20 families were identified, with 18, 28 and 38 species found in open grazed areas, and in 5-and 10-year grazing exclosures, respectively. The 10-year grazing exclosures had a higher(P <0.05) species richness and plant densities compared to the 5-year grazing exclosures and the open grazed areas. The population structure and regeneration status of woody species in both grazing exclosures showed an inverted J-shape, indicating a healthy regeneration status, whereas hampered regeneration was observed in open grazed areas. The establishment of grazing exclosures had positive effects in restoring woody plant diversity and improving vegetation structure and regeneration potentials of degraded grazing lands.展开更多
Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine...Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.展开更多
The modification in structure, composition, and diversity, shrub, as well as herb strata ofPinus koraiensis-Tilia amurensis-Abies nephrolepis forest after 16a of selection cutting in northeastern China was studied. In...The modification in structure, composition, and diversity, shrub, as well as herb strata ofPinus koraiensis-Tilia amurensis-Abies nephrolepis forest after 16a of selection cutting in northeastern China was studied. In the selection cutting forest, individuals with small DBH classes characterized size distribution. The virgin forest, on the other hand, was mainly composed of individuals having larger DBH classes. The density of dominant species and the species diversity at tree stratum in the selection-cutting stand was significantly larger than that of in the primeval forest. The shrub layer also showed a similar result. However, the herb layer had comparatively low species diversity. Large growing space and strong light in the artificial gaps must have provided opportunities for the species of shade tolerance or shade intolerance to establish on the stand. The juveniles of non-pioneer species, which were hardly found in highly shaded virgin forest, were also released by the disturbance. Regeneration in the selection-cutting stand was prompted by the disturbance, where the density of saplings occurred nearly 3 times as much as that in the virgin stand. The growth of shrub layer was improved due to the alteration in light condition. The projection volume of the herb layer was less affected. Restoration of a semi-virgin forest to the original status after selection cutting could be possible in several decades. However, for those subjected to clear cutting, it might take several centuries. In order to promote biodiversity, it is reasonable to practice selection cutting in communities for consisting of species with various levels of shade tolerance.展开更多
基金supported by the Fundamental Research Funds for the Central Universities (572017PZ03,2572020DR04 and 2572019CP16)。
文摘As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.
基金supported by National Natural Science Foundation of China(41271115)
文摘Soil seed banks can provide a mechanistic for understanding the recruitment dynamics and can inform conservation management of ecosystems. To investigate the contribution of soil seed banks to vegetation restoration in moving sand dune systems, we compared seed structure and species similarity between soil seed banks and standing vegetation among moving sand dunes, ecotones and dune slacks in northeast China. Average seed density in dune slacks was greater than in ecotones or moving sand dunes. Seed density in the soil layer of 0-10 cm was greater than at 10-20 cm both in the moving sand dunes and the eco- tones, but seed densities were similar at depths of 10-20 and 20-30 cm in moving sand dunes. Moreover, the spatial autocorrelation of seed density on moving sand dunes was weak but was strong on the ecotones and dune slacks. The species in the soil seed bank of moving sand dune systems were nearly all annuals, and the low similarity was mainly due to the lack of perennial species that were common in standing vegetation. Consequently, vegetation restoration cannot mainly rely on the soil seed banks in the movingsand dunes and more attention should be paid to protection of the dune slacks because they are the main source of seed disperse and seedling recruitment in moving sand dune systems.
基金supported by the National Natural Science Foundation of China[32101511]the Chinese Universities Scientific Fund[2452020137]and[2452021073]the Natural Science Basic Research Program of Shaanxi[2021JQ-155]。
文摘Black locust(Robinia pseudoacacia L.)plantations have contributed significantly to soil and water conservation and ecological reconstruction on China’s Loess Plateau.Understanding the impact of stand and environment on species composition of understory woody plants will improve the stability of existing black locust plantations.Ten stands were selected in second-generation black locust plantations in tableland and gully areas of the Loess Plateau.The number of understory tree species in the tablelands was significantly lower than in the gully stands.Regenerated black locust(19.76%)and Rubus corchorifolius L.f.(64.85%)were the most abundant understory tree and shrub species,respectively,in the tableland stands;Broussonetia papyrifera(L.)L’Hér.ex Vent.(6.77%)and Acanthopanax senticosus(Rupr.Maxim.)Harms.(37.22%)were most abundant in the gully stands.Species richness(S),Shannon diversity(H),and evenness index(J)of the understory plants were significantly lower in the tableland stands than in the gully stands.More diverse understory species and community structures occurred in the gully stands.Differences in species diversity among landform positions may be attributed to differences in soil moisture.In addition,77.57%of the variation in understory species composition was explained,among which shrub and herb coverage,stand age,leaf area index,slope and total soil phosphorus in the 10-20 cm layer were the main factors.Soil organic carbon and total potassium significantly impacted S,H and J.Considering the environmental conditions and the biological characteristics of the plants investigated,R.corchorifolius should be given priority in the development of tableland stands,while B.papyrifera and Celtis sinensis Pers.should form mixed forests with black locust in gully stands.This management could promote biodiversity and stability of the existing black locust plantations but also optimize regional landscape patterns.
基金supported financially by Ethiopian Biodiversity Institute。
文摘Species composition,structure,regeneration,and management status of Jorgo-Wato Forest(JWF)was studied.Number of individuals,diameter at breast height(dbh)and height of woody species(dbh≥2.5 cm)were counted and measured in each plot.Group discussions with local farmers residing around JWF were carried out to understand the management of the JWF.Forest structural attributes were computed using descriptive statistics;correlation was used to assess relationships between the structural variables.A total of 4313 individuals(dbh≥2.5 cm)with a density of 1477 ha-1 were recorded,the number of species and individuals decreasing with increasing dbh classes.Species with the highest Importance Value Index(IVI)were Pouteria adolfifriedericii(37.7),Syzygium guineense subsp.afromontanum(23.6),Dracaena afromontana(20.5),Chionanthus mildbraedii(15.9),and Croton macrostachyus(12.3).Overall distribution of woody plants across size classes exhibited a reverse J-pattern,suggesting a healthy population structure and good regeneration.Nevertheless,some species were not represented in smaller diameter classes,including juvenile phases,which indicate a lack of regeneration.For these species,monitoring and enrichment planting would be necessary,along with curbing illegal cutting and coffee farming in the natural forest.Management interventions in the JWF need to consider livelihood options and to respect the rights of local communities.
基金supported by the National Natural Science Foundation of China(Project Nos.U23A20142 and 32370013)Hainan Province Science and Technology Special Fund(ZDYF2023RDYL01)+1 种基金the Hainan Institute of National Park,HINP,KY-24ZK02the Yunnan Province Expert Workstation Program(No.202205AF150014)。
文摘Polypores play a cru cial role in energy recycling and forest regeneration in forest ecosystems.The majority of them are wood degraders;some are forest pathogens and others are ectomycorrhizal symbionts.The basidiocarps provide food and shelter for many organisms,mostly invertebrates,but also some vertebrates,as well as food and medicine for humans.Despite extensive research on the species diversity and phylogenetic relationships of polypores in recent years,there remains a lack of comprehensive understanding of their distribution patterns and species composition at the large scale.Checklists of polypores from the tropical zone,including tropical Africa,tropical America,and tropical Asia,were analyzed for species diversity,distribution patterns,major taxa,and nutritional modes.A total of 1,902 polypore species was found in the three regions,representing 8 orders,46families,and 250 genera of Agaricomycetes.The orders Polyporales(especially the family Polyporaceae)and Hymenochaetales(especially the family Hymenochaetaceae)had the most prolific taxa,with their species accounting for 93.4%of the total polypores listed.Each of 1,565(or 82.3%)of the total 1,902 species were found in only one of the three regions studied,and we treat them temporarily as"regional endemic species".Only 141species were shared among all three regions,accounting for a mere 7.4%.Tropical Africa and tropical America had the greatest number of shared species and the highest S?rensen similarity index(SC)value.Tropical forests had a higher species richness compared with temperate to boreal forests of the Northern Hemisphere,and in addition,also a higher proportion of white rot polypores compared to brown rot and ectomycorrhizal species.This study outlines the distribution patterns and species diversity of polypores in the world,shedding light on their ecological significance in diverse ecosystems.
基金funded by the Guizhou Science and Technology Department under Grant(QKHLHZ[2016]7447)the first-class discipline construction project of Guizhou Province under Grant(GNYL[2017]007).
文摘Background:Urban remnant forests are embedded in urban areas and are threatened directly and indirectly by urbanization.The direct effects(e.g.,loss of area)have been well studied.However,knowledge about the indirect influence of urbanization through edge effects on the biodiversity in remnant forests is limited.Methods:In this study,we surveyed woody plant species in 72 plots in nine remnant forest patches in Guiyang,China.We examined the influences of urbanization and edge effects on the species diversity and composition of woody plants in remnant forests.We compared alpha diversities and quantified compositional dissimilarities in interior and edge sites at different levels of urbanization.We also measured the niche width of the recorded plant species and assessed whether high levels of urbanization and edge effects increased the number of generalist species.Results and conclusions:The Shannon index,the Simpson index and the Pielou index of adult trees were lowest in the edge habitat under high levels of urbanization.Significant differences in the Shannon index and the Simpson index of sapling/seedling were detected between interior and edge sites under low urbanization.The edge effects on the species composition of adult trees were intensified by high levels of urbanization.Woody plant species with wide niche widths were more abundant at edge sites under high levels of urbanization.Therefore,we recommend that urban expansion surrounding remnant patches should be strictly controlled to alleviate edge effects on biodiversity.
基金the National Natural Science Foundation of China(31870443)the Fundamental Research Funds for the Central Universities(2572016CA03)the Heilongjiang Postdoctoral Funds(LBH-Z16014).
文摘Wetland restoration had been implemented for more than two decades in Sanjiang Plain,Northeast China.To assess the restoration effi ciency of wetland vegetation,we investigated plants composition of community,plant species diversity and aboveground biomass of restored sites in a chronosequence of restoration(1,2,3,6,8,11,15 and 25 years)in the Sanjiang Nature Reserve.As comparison,we also investigated the same factors in a cropland and a natural marsh adjacent to the restored sites.The results showed that wetland plant species can invade quickly after croplands were abandoned when there were suitable hydrology conditions.On the early stage of the restoration,weeds were main plant species in the restored sites.Wetland species appeared at the same time but diff ered from the dominant species from the adjacent natural marshes.Common native wetland species could dominance the community after 3-year restoration.Species richness and diversity increased on the early stage,and then decreased to the similar level of the natural marsh with the extension of restoration.Plant biomass could restore easier than the species composition and diversity.Our results indicated that plant species composition and diversity of abandoned reclaimed wetlands can restore gradually by natural succession in Sanjiang Plain.However,25-year restoration site had similarity index of only 56%with the natural marsh,which revealed that two decades are not enough for complete restoration of vegetation.
文摘The study focuses on the dynamics and biomass production （g·m-2） of understory （herbaceous） plant community under broad-leaf forests consisting of Quercus leucotrichophora （Banj-oak）, Quercus floribunda （Tilonj-oak） and Quercus semicarpifolia （Kharsu-oak）, respectively in central Himalaya, India. With increasing altitudes, the den-sity and biomass decreased significantly across the three types of forests. Banj-oak forest harboured the maximum density and biomass among the other sampling sites. The mean density of herb species in two contrasting orientation differed significantly （p0.05）, showing relatively higher density on slope orientation （west）. Across the sites, total production declined significantly with increasing altitude of the sites （p0.05）, and Banj-oak forest presented the highest production.
基金the National Natural Science Foundation of China (Grant No.30270282 30170147)
文摘The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea + Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, i.e., Schefflera, Sterculia and Cleistocalyx + Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04–2.953 and 64.2%–74% respectively, but those of the Endospermum community are 4.74 and 79% respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.
文摘Soil animal communities of Secondary forest,Platycladus forest andQuercus acutissima forest in Confucian graveyard of Qufu were investigated. 3583 specimens were collected, belonging separately to 5 Phylums, 11 Classes and 23 Orders. Two dominant groups and 9 common groups account for 94.45% of the total numbers. The soil animals in these three forest habitats differ in composition, ecological distribution and important indices. The dominant groups of soil animals in the three forests were the same, but other groups differ more greatly. Diversity index (H′) and evenness index (E) of soil animal in Secondary forest are the highest, and yet dominance index (C) inQuercus acutissima forest is the highest. Most soil animals in each forest habitats congregate to the surface soil layer. Their sorts and individual numbers are all layer I>II>III. It is very similar for composition of soil animals in the three forests.
基金We acknowledge the University of the Basque Country(UPV/EHU)for the given fellowship(PIF20/27)the Basque Government through the given grant(GIC21/201-IT1648-22)We also acknowledge the Basque Government for the doctoral fellowship(PRE_2022_2_0194)that has partially supported this research.
文摘In the last century,eucalypt plantations are increasing all over the world.Concretely,in the Basque Country(northern Iberian Peninsula),7%of pine plantations have been recently substituted by eucalypt plantations,where little is known about their ecological impact on soil and plant diversity.However,the most relevant impact is due to forest management,as Eucalyptus globulus Labill.plantations have a short harvesting cycle,12–15 years rotations.In fact,the species is able to regenerate from stumps;therefore,those plantations are replanted after 3–4 rotations.This type of invasive and frequent management could lead to further adverse effects on the ecosystem.The aim of this study was to characterise and compare the eucalypt plantations newly established(New:never been harvested)with older ones(Old:several times harvested and grown from stumps),having been established for at least 35 years,and to identify the primary factors that could influence the richness and diversity of vascular plant species in those plantations.The results indicated that both plantations exhibited comparable characteristics with respect to deadwood(volume and decay stage)and tree size and density.However,the Old plantations exhibited higher forest heterogeneity,pH,and higher shrub and herb richness and diversity.Overall,generalist and invasive species were found in the New plantations,while in the Old plantations,typical species of the native forests were also observed.The factor that influenced plant diversity was the volume of deadwood.Regarding life forms,higher altitude and proximity to watercourses favoured tree diversity;and lower canopy cover,shrub diversity.In conclusion,the longer the plantation has been established,the greater the number of species that are able to survive and adapt.This is probably due to the fact that management disturbance is specific and not sufficient to remove the already established plants and the soil seed bank.
基金supported by National Natural Science Foundation of China (No.30471386)Japanese Society for Promotion of Sciences (15P03118)
文摘Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 5400 stems-ha^-1 （ -〉 3.0 cm DBH）; 64% of those stems were smaller than 10 cm DBH. The total basal area was 54.4 m^2-ha^-1, of which Castanopsis sieboldii contributed 48%. The forest showed high species diversity of trees. 80 tree species （≥ 3.0 cm DBH） from 31 families was identified in the thirty sampling plots. C. sieboldii and Schima wallichii were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were, 3.36 for Diversity index （H＇）, 0.71 for Equitability index （J＇） and 4.72 for Species richness index （S＇）, all of which strongly declined with the increase of importance value of the dominant, C. sieboldii. Measures of soil nutrients indicated low fertility, extreme heterogeneity and possible A1 toxicity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil exchangeable K^＋, Ca^2＋, and Ca^2＋/Al^3- ratio （all p values 〈0.001） and a negative relationship with N, C and P. The results suggest that soil property is a major factor influencing forest composition and structure within the subtropical forest in Okinawa.
基金supported by the Project of Public Welfare Technology Research in Zhejiang Province(LGN21C160010)the National Key Research and Development Program of China(No.2017YF C0505502)。
文摘Functional traits of trees are significantly associated with their adaptation strategies and productivity.However,the effects of species composition and mixing proportion on the functional traits of trees grown in mixed plantations have not been studied extensively.In this study,planting experiments(duration about seven months)were used to study variations in functional traits and biomass allocation of C unninghamia lanceolata(Lamb.)Hook and Phoebe bournei(Hemsley)Yang seedlings in five different mixes(0C:4P,1C:3P,1C:1P,3C:1P,and 4C:0P).Total leaf area per seedling increased in each species as its respective proportion in the mixture decreased.However,the specific leaf area decreased for P.bournei under low percent composition,and the specific leaf area for C.lanceolata differed only marginally among the plantings.The net photosynthetic rates of the two species were higher in the mixed plantings than in their corresponding monocultures,whereas the transpiration rate,stomatal conductance,and instantaneous water use efficiency were not different among the plantings.The average root length and root surface area of C.lanceolata and P.bournei were higher in the mixed plantings than in their monocultures.Specifically,root surface area of C.lanceolate and both root length and surface area of P.bournei increased significantly in the 1C:3P and 2C:2P mixed plantings.Leaf,stem,root,and total dry mass per seedling for C.lanceolata decreased with its increasing percent composition in the mixed plantings,while these variables varied less for P.bournei.The plasticity of biomass allocation was relatively low for both species.Total biomass per planting was higher in the mixed plantings than in the monocultures.Our study indicates that species composition and mixing proportion can considerably affect the functional traits of C.lanceolata and P.bournei.The increase in productivity in the mixed plantings may be partially attributed to low rates of competition between the two species,and future studies should examine the different interspecies relationships.The results of this study can be used to improve plantation productivity and ultimately increase the sustainability of tree products and help to better understand the adaptation strategies of plant coexistence.
基金We express our sincere appreciation to Xiao-Yu Guo,Yao Fu,Yu Dong,Tian-Bo Wang,Yi-Fu Wang for their fieldwork assistance,and to the members of Langxiang Forestry Bureau for their friendship and assistance.
文摘In order to understand the management of regional vegetation,numerical classification and ordination are widely used to investigate community distribution and vegetation features.In particular,two-way indicator-species analysis programs(TWINSPAN)classifies plots and species into different groups.De-trended correspondence analysis(DCA)and canonical correspondence analysis(CCA)reflects the relationship between community and site conditions.Afforestation with Larix olgensis Herry.Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains.The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process.Twenty-eight L.olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method.Species composition,community structure attributes of diversity,and site conditions were analyzed.Communities were classified by TWINSPAN into five successional stages:immature,juvenile,mid-aged,nearmature and mature.Classifications were validated by DCA and CCA analysis.Site conditions such as soil and litter thickness,soil organic matter,soil density,and pH were measured.Successional stages varied in community composition and species population,accompanied by time from afforestation and a gradient of site conditions.This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions.The study showed that L.olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.
基金funded through the project‘Bio Holz’(grant no.01LC1323A)in the funding program‘Research for the Implementation of the National Biodiversity Strategy(F&U NBS)’by the German Federal Ministry for Education and Research(BMBF)and the German Federal Agency for Nature Conservation(Bf N)with funds provided by the German Federal Ministry for the Environment,Nature Conservation,Building and Nuclear Safety(BMUB)supported by the DFG Priority Program 1374‘Infrastructure-Biodiversity-Exploratories’。
文摘Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.
文摘The structure and species composition as well as their changes in a climax forest, dominated byPinus koraiensis-Tilia amurensis andFraxinus koraiensis, were observed with an interval of 10 years. The number of tree species was 16 in 1981, which was kept unchanged. Density was increased from 510 to 535 stems/hm2, and basal area from 35.19 to 38.17 m2/hm2. Average stand DBH remained nearly unchanged. The total mortality of the stand was very low, 0.61% per year.Fraxinus andPinus were declining in population size, the highest mortality rate for the former, and the largest death number for the latter.Tilia showed a rapid increasing of 14.9%, and the density of saplings (DBH 3-8 cm) was 71 stems/hm2, led the top among canopy-layer species.Acer mono, similar toTilia, showed a type of continuous regeneration which was represented by the reverse J-shape of DBH distribution and compensation ability to mortality. Sub-canopy species such asAcer pseudo-sieboldianum, Maackia amurensis etc. presented a stable status by self-maintenance. Based on the fact of the decreasing of dominant populations, it is predicted that the composition of the community was changing gradually, the rising of broad-leaved components versus the declining of coniferous species.
基金the financial support of Tigray Agricultural Research Institute and Humera Agricultural Research Center,northern Ethiopia
文摘Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, we studied woody plant structure, diversity and regeneration potentials in 5-and 10-year grazing exclosures in comparison with open grazed sites in a semi-arid environment. Data on species diversity, abundance, structure, basal area, frequency, density, and regeneration status were collected from 270 sample plots. Forty-one woody species representing 20 families were identified, with 18, 28 and 38 species found in open grazed areas, and in 5-and 10-year grazing exclosures, respectively. The 10-year grazing exclosures had a higher(P <0.05) species richness and plant densities compared to the 5-year grazing exclosures and the open grazed areas. The population structure and regeneration status of woody species in both grazing exclosures showed an inverted J-shape, indicating a healthy regeneration status, whereas hampered regeneration was observed in open grazed areas. The establishment of grazing exclosures had positive effects in restoring woody plant diversity and improving vegetation structure and regeneration potentials of degraded grazing lands.
基金supported by the National Natural Science Foundation of China (42071073,31971487)Youth Innovation Promotion Association of the Chinese Academy of Sciences (2021366)+2 种基金Guangxi Key Research and Development Program (AB17129009)the Hechi Distinguished Expert Program to Fuping Zengthe Guangxi Bagui Scholarship Program to Dejun Li。
文摘Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.
文摘The modification in structure, composition, and diversity, shrub, as well as herb strata ofPinus koraiensis-Tilia amurensis-Abies nephrolepis forest after 16a of selection cutting in northeastern China was studied. In the selection cutting forest, individuals with small DBH classes characterized size distribution. The virgin forest, on the other hand, was mainly composed of individuals having larger DBH classes. The density of dominant species and the species diversity at tree stratum in the selection-cutting stand was significantly larger than that of in the primeval forest. The shrub layer also showed a similar result. However, the herb layer had comparatively low species diversity. Large growing space and strong light in the artificial gaps must have provided opportunities for the species of shade tolerance or shade intolerance to establish on the stand. The juveniles of non-pioneer species, which were hardly found in highly shaded virgin forest, were also released by the disturbance. Regeneration in the selection-cutting stand was prompted by the disturbance, where the density of saplings occurred nearly 3 times as much as that in the virgin stand. The growth of shrub layer was improved due to the alteration in light condition. The projection volume of the herb layer was less affected. Restoration of a semi-virgin forest to the original status after selection cutting could be possible in several decades. However, for those subjected to clear cutting, it might take several centuries. In order to promote biodiversity, it is reasonable to practice selection cutting in communities for consisting of species with various levels of shade tolerance.
