Estimating the relative roles of top-down and bottom-up forces on insect herbivore populations: a classic study revisited.
Estimating the relative roles of top-down and bottom-up forces on insect herbivore populations: a classic study revisited.
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估计自上而下和自下而上的力量对昆虫食草动物种群的相对作用：重新审视一项经典研究。
DOI：
10.1073/pnas.94.17.9176
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发表时间：
1997
影响因子：
11.1
通讯作者：
G. R. Gradwell
中科院分区：
文献类型：
--
作者：
Mark D. Hunter;George C. Varley;G. R. Gradwell
虽然大多数生态学家都认为，自上而下和自下而上的力量（分别是捕食和资源限制）共同影响食草动物的种群，但事实证明，很难估计这些力量在陆地系统中的相对贡献。使用的时间序列分析的人口计数记录超过16年的实验数据相结合，我们提出了第一次估计的相对作用，自上而下和自下而上的力量的人口动态的两个陆地昆虫食草动物的英国橡树（栎robur）。数据表明，在冬季蛾，Operophtera brumata，密度的时间变化主要是由蛹捕食者的时滞效应。通过比较，O. brumata密度由寄主植物质量控制。总体而言，自上而下的力量解释了34.2%的群体方差，自下而上的力量解释了17.2%的群体方差，还有48.6%的群体方差无法解释。相比之下，人口的绿色橡树tortidana，Tortidaviridana，似乎占主导地位的自下而上的力量。资源限制，表示为种内竞争幼虫之间的橡树叶，解释了29.4%的人口方差。宿主质量效应解释了另外5.7%的群体方差。我们没有发现主要的自上而下的影响T。viridana种群一个未知因素导致T。在16年的研究期间，viridana种群解释了剩余的大部分无法解释的方差。我们讨论了观察到的昆虫物种之间的差异和效用的时间序列分析作为一种工具，在评估草食动物种群自上而下和自下而上的力量的相对重要性。
Although most ecologists agree that both top-down and bottom-up forces (predation and resource limitation, respectively) act in concert to influence populations of herbivores, it has proven difficult to estimate the relative contributions of such forces in terrestrial systems. Using a combination of time-series analysis of population counts recorded over 16 years and experimental data, we present the first estimates of the relative roles of top-down and bottom-up forces on the population dynamics of two terrestrial insect herbivores on the English oak (Quercus robur). Data suggest that temporal variation in winter moth, Operophtera brumata, density is dominated by time-lagged effects of pupal predators. By comparison, spatial variation in O. brumata density is dominated by host-plant quality. Overall, top-down forces explain 34.2% of population variance, bottom-up forces explain 17.2% of population variance, and 48.6% remains unexplained. In contrast, populations of the green oak tortrix, Tortrix viridana, appear dominated by bottom-up forces. Resource limitation, expressed as intraspecific competition among larvae for oak leaves, explains 29.4% of population variance. Host quality effects explain an additional 5.7% of population variance. We detected no major top-down effects on T. viridana populations. An unknown factor causing a linear decline in T. viridana populations over the 16-year study period accounts for most of the remaining unexplained variance. We discuss the observed differences between the insect species and the utility of time-series analysis as a tool in assessing the relative importance of top-down and bottom-up forces on herbivore populations.