摘要
在淡水湿地生态系统中,水位通常是制约植被生长和繁殖动态的关键因素,进而对物种组成、群落演替和植被分布格局产生决定性影响。无性繁殖是洞庭湖湿地克隆植物适应环境胁迫的重要策略之一,以洞庭湖湿地典型克隆植物-短尖苔草(Carex brevicuspis C.B.Clarke)为对象,研究了不同分布高程(23.7 m和25.8 m)的植物对水位变化(0 cm,-15 cm,-30 cm)的生长和繁殖特征响应。结果表明:水位变化对不同分布高程分布短尖苔草的生长和克隆繁殖特征均产生显著影响(P<0.05)。对高程区的短尖苔草而言,克隆繁殖特征如分株数、分株总生物量、芽数和芽生物量随水位的降低而增加,而对生长特征(株高及总生物量)无显著影响(P>0.05),表明适当干旱有利于高程区苔草的克隆繁殖。对于低程区分布短尖苔草而言,水位变化对其生长特征有显著影响(P<0.05),如株高和总生物量随着水位的降低而增加;分株数和总芽生物量等克隆繁殖特征则随水位的降低而减少,而水位对低程区短尖苔草的分株总生物量和总芽数影响不显著(P>0.05)。因此,短尖苔草的克隆繁殖特征除受到水位的影响外,还受其分布高程的影响。可见,同一种短尖苔草因长期适应于不同生境而对相同的环境胁迫表现出了不同的生长繁殖策略,
In freshwater wetland ecosystems,water level is the key factor constraining the growth and reproduction of macrophytes,and consequently influences species composition, community succession, and vegetation distribution.Reproduction is the fundamental behavior and the key life process affecting plant population persistence. Many clonal plants possess the capacity for both sexual reproduction through seeds and clonal propagation（ asexual reproduction） through bud banks. In clonal plants,the trade-offs between sexual and asexual reproduction are influenced by biotic variables,such as plant size and population age,and abiotic factors,such as resource levels and successional status. In perennial-dominated ecosystems,such as grasslands and wetlands, clonal reproduction predominates over sexual reproduction. Asexual reproduction is one of the key strategies that the clonal plants in Dongting Lake wetlands use to adapt to environmental stresses. In this study,we investigated the effects of water levels（ 0 cm,- 15 cm,and- 30 cm） on the growth and reproductive characteristics of a typical clonal plant- Carex brevicuspis,which is distributed across different elevational zones（ 23.7 m and 25.8 m asl.） at Dongting Lake wetlands. The results showed that water level has a significant impact on thegrowth and clonal characteristics of the C. brevicuspis found at both elevations（ P〈0.05）. The number of ramets and buds,and the biomass of C. brevicuspis found in the high-elevation zone increased as the water level decreased,whereas the growth characteristics（ height and total biomass） did not change significantly（ P〉0.05）. Therefore,a moderate drought improves the clonal propagation of C. brevicuspis in the high-elevation zone. Water level has a significant impact on the growth characteristics（ P〈0.05） of C. brevicuspis growing in the low-elevation zone because height and total biomass increased as the water level decreased. The number of ramets and bud biomass decreased as the water level declined,while the number of buds and the ramet biomass were not significantly affected by water level（ P〉0.05）. Both the plant height and total biomass of C. brevicuspis growing in the low-elevation zone increased as the water level declined,whereas the number of ramets decreased. Therefore,the clonal characteristics of C. brevicuspis were affected not only by the water level,but also by the elevation that the plant occupies. Our results also suggested that C. brevicuspis could access resources in patchy habitats through plasticity in morphological traits and biomass allocation. C. brevicuspis distributed in the high-elevation zone could adapt to a nutrient-rich environment by allocating more resources to the belowground parts and fewer resources to the aboveground shoots. In contrast,C. brevicuspis growing in the high-elevation zone could adapt to the low level of available resources or stressful environments by allocating more resources to the aboveground shoots and fewer resources to the belowground parts. Nevertheless,C. brevicuspis growing in the low-elevation zone did not respond significantly to changes in resource levels through biomass allocation plasticity,which suggests that C. brevicuspis found in the low-elevation zone may not acclimate as quickly to the changes in wetland habitats as the plants growing in the high-elevation zone. These results indicated that C. brevicuspis can deploy different growth and reproductive strategies in response to water stress because of long-term adaptation to particular habitats.
出处
《生态学报》
CAS
CSCD
北大核心
2016年第7期1959-1966,共8页
Acta Ecologica Sinica
基金
国家科技支撑计划项目(2014BAC09B03)
国家基础性工作调查专项(2013FY111802)
国家自然科学基金(31170342)
关键词
水位
克隆繁殖
湿地植物
洞庭湖
water level
clonal propagation
wetland plants
Dongting Lake
作者简介
通讯作者．E—mail：xvh@isa．ac．cn
