生态系统是多么常被自上而下的控制? 在草原,和鸟类系统的实验,随着时间和空间的推移
Gary E Belovsky1, Jennifer B Slade1
1Department of Biological Sciences University of Notre Dame Notre Dame Indiana USA.
概括
捕食 (自上而下) 很少控制生态系统. 长期的鸟类排斥实验揭示了植物和种群的各种反应,受地点,年份和气候变化的影响,挑战了简单的生态控制模型.
科学领域:
- 生态生态学 生态生态学
- 生态系统动力学 生态系统动力学
- 捕食者与猎物的互动
背景情况:
- 生态系统通常被认为是通过掠食 (自上而下的控制) 进行调节的.
- 这种自上而下的控制假设表明,捕食者限制了猎物种群,这反过来影响了较低的营养水平.
- 然而,生态相互作用的复杂性可能会导致各种各样的反应.
研究的目的:
- 实验测试陆地生态系统中自上而下的控制的普遍性和一致性.
- 调查鸟类排斥如何影响长时间的植物和种群.
- 了解生态系统对掠食压力的反应的变化.
主要方法:
- 在四个草原息地进行了34年的实验,包括鸟类隔离和控制.
- 在100平方米的地块上测量了植物,和蜘蛛的数量.
- 利用决策树/差异分析来确定关键的生态驱动因素.
主要成果:
- 在只有13.2%的病例中观察到自上而下的控制.
- 生态系统的反应有很大的变化,植物和虫在各种组合中增加/减少.
- 使用特定的生态指标 (例如,ANPP,食用植物生物量) 可以预测植物和虫的反应.
结论:
- 在这些草原生态系统中,自上而下的控制不是占主导地位的力量.
- 生态系统的反应在空间和时间上高度可变,受到气候变化等因素的影响.
- 生态系统中的食用相互作用比通常通过简单的自上而下的或自下而上的框架建模的更复杂和更可变.
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