草地沙化度对补播地八角外观性状及繁殖策略的影响

Effects of desertification degree on the appearance traits and reproductive strategies of Astragalus bhotanensisin in reseeding grassland

摘要:

【目的】 为沙化治理、草地复壮及“四库”建设提供技术支撑，以提升青藏高原沙化高寒草甸生产力。【方法】 分别在4个沙化度（未沙化、轻度、中度和重度）草地上补播地八角，在465 d后，通过测定构件性状、生物量结构及繁殖分配等指标，研究草地沙化度对补播地八角外观性状及繁殖策略的影响。【结果】 沙化度影响地八角叶、茎、根等性状，随沙化度加重，分枝数、根长、根数、根体积增加，株高显著降低（P＜0.05）。中度沙化可显著增加复叶数量、茎长度、茎径和根径（P＜0.05），中度沙化时叶、 茎、根、花的绝对生物均为最大，重度沙化可显著增加小叶数量而抑制茎长。沙化度显著影响地八角花穗数、花数、果数和种子数（P＜0.05），对荚果长及种子千粒重无显著影响。沙化度显著影响地八角克隆繁殖与有性繁殖指标（P＜0.05），随沙化度克隆繁殖能力降低。轻度沙化繁殖分配和繁殖指数最大， 中度沙化繁殖效率指数最大，重度沙化克隆效率指数最大。【结论】 地八角通过形态可塑性、生物量分配和繁殖权衡，形成与沙化度相应的外观株丛结构、生长方式及繁殖策略。地八角可作为抗沙固沙草种，在中、重度沙化草地植被修复或重建中推广应用。

Abstract:

【Objective】 To provide technical support for desertification control，grassland revitalization，and the construction of "four reservoirs" ，aimed at enhancing the ecological productivity of desertified alpine meadows on the Qinghai Tibet Plateau.【Method】 The seeds of Astragalus bhotanensis，a leguminous plant，were reseeded in grasslands with four levels of desertification （non sandy，light，moderate and heavy desertification）. Key indicators such as component traits，biomass structure，and reproductive allocation were measured to examine differences in appearance traits and reproductive strategies of reseeded A. bhotanensis.【Result】 The level of desertification significantly influenced the traits of leaves，stems，roots，and flowers of A. bhotanensis （P＜0. 05）. The number of branches，root length，root number，and root volume increased significantly with desertification severity，while the plant height decreased with the desertification degree （P＜0. 05）. Moderate desertification significantly enhanced compound leaf number，stem length，stem diameter，and root diameter （P＜0. 05），resulting in the highest absolute biomass for leaves，stems，roots，and flowers. Severe desertification cincreased the number of small leaves but inhibited stem length. The degree of desertification significantly affected panicle，flower，fruit，and seed numbers of A. bhotanensis （P ＜0.05），but had no significant effect on pod length and seed thousand grain weight. Reproductive and sexual indicators of A. bhotanensis were also significantly affected by desertification （P＜0. 05）. Clone reproductive ability decreased with the desertification degree. Mild desertification yielded the highest reproductive allocation and reproductive index，moderate desertification achieved the highest reproductive efficiency index，and severe desertification recorded the highest cloning efficiency index.【Conclusion】 A. bhotanensis could form an external plant cluster structure，growth mode，and reproductive strategy corresponding to desertification degrees by morphological plasticity，biomass allocation，and reproductive balance. As a sand-resistant and sand-stabilizing leguminous grass，A. bhotanensis demonstrates significant potential for vegetation restoration and reconstruction of moderately to severely desertified grasslands.