摘要
植物对不同功能性状进行权衡,通过表型可塑性达到对异质生境的适应是植物的一种生态对策。羊草(Leymus chinensis)是欧亚温带草原东缘的主要优势植物,研究其对放牧的表型反应对揭示草原生态系统的放牧响应机制具有代表意义。该文以内蒙古呼伦贝尔草甸草原为例,通过设置不同放牧压力与围封的长期试验,研究了羊草茎叶功能性状对放牧的可塑性响应模式。结果表明:1)与长期围封相比,长期放牧导致羊草茎叶性状显著小型化,其中,株高和个体地上生物量分别降低76.82%和89.88%,但3年短期围封对茎性状影响不显著,说明羊草表型矮小化现象具有一定的保守性;2)通过排序构建羊草性状可塑性变化谱,发现茎质量、总质量、茎高、株高、叶面积等为对放牧响应的敏感性状,而叶片数、茎粗、叶宽等较为稳定,为惰性性状;3)放牧干扰下,羊草性状可塑性程度与其变异性之间符合y=y0+aebx拟合关系,随着植物性状的响应强度增大,其变异性增强;4)偏最小二乘法分析发现茎长、株高、叶面积、叶长等性状的投影重要性指标大于1,对地上生物量变化的解释率为68.6%,是导致长期放牧下羊草个体生物量降低的主要因子。研究认为,矮化型变是羊草的避牧适应对策,在亚稳态下,通过不同性状的权衡,充分利用环境资源完成其生活史。
Aims Adaptation of plants to their habitats through phenotypic plasticity in which they trade off various kinds of functional traits is an important ecological strategy. Whereas plant functional traits and its effects on grassland ecosystem functioning have received much attention, the importance of grazing effects on functional traits is poorly understood. This study, therefore, aimed to analyze the responding model of Leymus chinensis functional traits to long-term grazing in semi-arid grassland. Methods The study was conducted in a field experiment involving treatments with various grazing and enclo-sure schemes in Nei Mongol. We compared the effects of long-term enclosure, short-term enclosure （SE）, mod-erate grazing （MG）, and heavy grazing on plant functional traits in L. chinensis. Partial Least Squares Regression was used to analyze the contributions of controlling factors on changes in biomass in response to grazing. Important findings The size of L. chinensis became smaller in plots subject to long-term grazing compared with in the plots of enclosures. It had a significant conservative property of plant dwarf which can be found in the SE plot. Interestingly, the variability increased significantly with the increasing of plasticity index of different func-tional traits. Also, some functional traits, such as aboveground biomass, plant height, mean leaf length etc., were sensitive traits to grazing. However, other indicators, such as leaf numbers, stem diameter, mean leaf width etc., which were inert functional traits. Stem length, plant height and other traits were main factors which cased the decreasing of L. chinensis aboveground biomass. On the whole, phenotypic change is an important adaptive strat-egy of L. chinensis to long term grazing.
出处
《植物生态学报》
CAS
CSCD
北大核心
2014年第5期440-451,共12页
Chinese Journal of Plant Ecology
基金
国家重点基础研究发展计划(973计划)(2014CB138802)
国家国际重大科技合作项目(2013DFR30760)
国家自然科学基金(70933004
71103185和71311120089)
国家科技支撑计划课题(2012BAD13B07)
中央级公益性科研院所基本科研业务费专项资金(1610332013007)
关键词
功能性状
羊草
草甸草原
过度放牧
表型可塑性
草原植物矮小化
functional trait
Leymus chinensis
meadow steppe
overgrazing
phenotypic plasticity
plant dwarf of grassland
