东北退化牧场恢复演替群落优势植物对去顶采食的生态适应机理研究

Research on ecological adaptability of herbage plants under livestock grazing system, is an important scientific issue, and also provides certain references for practical production. Research objectives include a pioneer species Artemisia scoparia in the early stage and four perennial tuft grasses in the transition period of restoration succession communities in northeast degeneration pasture, focusing on the mechanisms of ecological adaptability of two life form plants after topping damage. Situ research contents include age structure, plant matter production of different ages, seed production, root-crown vegetative propagation, senescence process of root crowns and roots of natural A. scoparia population under different grazing intensity, life history pattern of clonal modules, photosynthetic characteristics and tolerance physiological ecology of injury leaves in four natural grasses under different grazing disturbance intensity. Simulation experimental research include plasticity of seedling growth and seed production, as well as reproductive allocation, reproductive redistribution strategy by trade-off between seed size and quantity and r-K strategy regulation in A. scoparia population; growth and allocation strategy, photosynthetic characteristics and tolerance physiological ecology of intact leaves after topping damage of clones and modules in four tuft grasses. The external and internal leading factors of individual life span plasticity and mechanisms of ecological adaptation under diversity life history of A. scoparia would be revealed; convergent adaptation mechanism and evolutionary significance regulated by individual physiological and ecological and life history strategy of clonal modules on four bunchy grasses after topping damage would be revealed.

放牧系统牧草对家畜采食的生态适应性研究，既是重要科学问题，又具有指导生产实践价值。以东北退化牧场恢复演替初期先锋种猪毛蒿和过渡期四种多年生丛生型禾草为研究对象，开展两个生活型植物对去顶采食的生态适应机理研究，主要内容包括不同放牧干扰强度下天然猪毛蒿种群年龄结构及不同龄级植株物质生产、种子生产、根颈营养繁殖、根颈和根系构件衰老过程，四种天然禾草无性系构件生活史格局、采食损伤叶片光合生理特性与耐受性生理生态等原位实验研究，以及猪毛蒿幼苗个体生长与种子生产可塑性、生殖分配、种子大小与数量权衡的生殖再分配策略及r-K策略调节；四种禾草无性系及构件生长与分配策略、去顶后未受损叶片光合生理特性与耐受性生理生态等模拟实验研究。揭示猪毛蒿个体寿命可塑性的内外主导因子及其个体生活史多样性形成的生态适应机理，揭示四种丛生型禾草对放牧去顶采食在个体生理生态调节和无性系构件生活史策略调节的趋同适应机理及进化意义。

草原植物在整个生活史中随时遭受动物采食扰动，在漫长的进化过程中植物应对动物采食已经形成了多种多样的生态适应特性和生态策略。本项目以东北退化牧场恢复演替群落优势植物猪毛蒿、披碱草、冰草、硬质早熟禾、野大麦为研究对象，围绕其去顶采食的生态策略调节等适应机理，开展了种群数量动态、个体生理和营养繁殖等基础研究。具体内容包括：演替初期先锋种猪毛蒿生态策略调节及个体生活史多样性形成机理研究；演替过渡期优势种丛生型禾草生态策略调节及生理生态研究；不同生活型优势种植物对去顶采食响应的生态适应机理分析。获得重要的研究结果包括：创建了采用根颈再生次数对分株年龄的划分方法；获得在不同扰动生境中天然猪毛蒿种群植株普遍由3个龄级组成，个别由4个龄级组成，其年龄结构在无退化生境和中度退化生境为稳定型，重度退化生境为衰退型；东北草原黄蒿种群个体寿命最大为5年。创建了采用构件数量对无性系植物被动物采食后补偿性生长的估计方法；获得了三种披碱草属禾草在模拟采食处理时期上，抽穗期去顶显著增加肥披碱草和麦宾草的芽数量，显著降低圆柱披碱草苗数量，而拔节期去顶显著降低肥披碱草苗数量；刈割处理强度25%可显著增加麦宾草苗芽数量，50%可显著增加圆柱披碱草苗芽数量，100%可显著降低肥披碱草的苗芽数量；处理后麦宾草和圆柱披碱草苗和芽数量在完熟期均为超补偿生长，在果后营养期均为等补偿生长；肥披碱草在完熟期为等补偿生长，在果后营养期为等补偿或欠补偿生长；野大麦天然种群去顶处理后，其总生物量、芽数、苗数和分株数在幼龄级（丛径<10cm）均为超补偿或等补偿生长，其他龄级均为等补偿或欠补偿生长。野大麦实验种群刈割处理中，拔节期处理营养株生物量主要表现为超补偿或等补偿生长，总生物量为欠补偿或等补偿生长；开花期处理营养株生物量为等补偿生长，总生物量为欠补偿生长。本项目成果对无性系植物生态学基础理论和方法均有重要补充。