Land use and drought interactively affect interspecific competition and species diversity at the local scale in a semiarid steppe ecosystem
Land use and drought interactively affect interspecific competition and species diversity at the local scale in a semiarid steppe ecosystem
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DOI：
10.1007/s11284-008-0532-y
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发表时间：
2009-05-01
影响因子：
2
通讯作者：
Taube, F.
中科院分区：
文献类型：
--
作者：
Gao, Y. Z.;Giese, M.;Taube, F.
虽然了解放牧生态系统的短期动态和群落演替很重要，但很少有研究考虑放牧和干旱对物种组成的相互影响以及物种对总生物量的相对贡献。我们监测物种多样性和相对生物量的贡献，在一个网站保护放牧自1979年以来（UG79），并在冬季放牧（WG）和严重放牧（HG）网站。连续重度放牧导致植株高度降低，个体（分蘖或匍匐茎）较多但较小。干旱显着降低了所有网站的总植物密度。放牧对物种多样性的影响比干旱更大。在站点UG79的物种丰富度显着高于在网站WG和HG，而干旱只倾向于减少物种多样性。干旱胁迫和放牧干扰交互控制物种竞争和功能群。在UG79站，多年生禾草和杂类草对总生物量的贡献较大，而在WG站，多年生禾草对总生物量的贡献率超过97%。一年生杂类草和半灌木对总生物量的贡献在两个干旱年份后显着增加。无茎委陵菜的显著减少和一年生植物的大量增加表明，在长期干旱的条件下，该生态系统的多年生植被面临着灭绝的巨大危险。
Few studies have considered interactive effects of grazing and drought on species composition and the relative contribution of species to total biomass, although it is important to understand the short-term dynamics and community succession in grazed ecosystems. We monitored species diversity and relative biomass contribution at one site protected from grazing since 1979 (UG79), and at winter grazing (WG) and heavily grazed (HG) sites. Continuous heavy grazing resulted in lower plant height and more but small individuals (tillers or stolons). Drought significantly reduced total plant density on all sites. Grazing affected species diversity more than drought. Species richness at site UG79 was significantly higher than at sites WG and HG, while drought only tended to reduce species diversity. Drought stress and grazing disturbance interactively controlled species competition and functional groups. Both perennial grasses and forbs had greater contribution to total biomass at site UG79, and perennial grasses contributed more than 97% of total biomass at site WG. The contribution to total biomass of annual forbs and semi-shrubs significantly increased at site HG after two dry years. The significant decrease in Potentilla acaulis and a substantial increase in annual species at this site indicate that the perennial vegetation of this ecosystem is in great danger of extinction under conditions of prolonged drought.