Benedetti-Cecchi L
Dipartimento di Scienze dell'Uomo e dell'Ambiente, Pisa, Italy.
Nature. 2000 Sep 21;407(6802):370-4. doi: 10.1038/35030089.
Food-web models use the effect size of trophic interactions to predict consumer-resource dynamics. These models anticipate that strong effects of consumers increase spatial and temporal variability in abundance of species, whereas weak effects dampen fluctuations. Empirical evidence indicates that opposite patterns may occur in natural assemblages. Here I show that spatial variance in the distribution of resource populations is sensitive to changes in the variance of the trophic interaction, in addition to the mean effect of consumers, relative to other causes of spatial variability. Simulations indicate that both strong and weak direct effects of consumers can promote spatial variability in abundance of resources, but only trophic interactions with a large mean effect size can reduce variation. Predictions of the model agree with the results of repeated field experiments and are consistent with data from published consumer-resource interactions, proving to be robust across widely varying environmental conditions and species' life histories. Thus, food-web models that embody variance in trophic interactions may have increased capacity to explain the wide range of effects of consumers documented in empirical studies.
食物网模型利用营养相互作用的效应大小来预测消费者 - 资源动态。这些模型预测，消费者的强烈影响会增加物种丰度的空间和时间变异性，而微弱影响则会抑制波动。实证证据表明，自然群落中可能会出现相反的模式。在这里我表明，除了消费者的平均效应外，相对于空间变异性的其他原因，资源种群分布的空间方差对营养相互作用方差的变化敏感。模拟表明，消费者的强直接效应和弱直接效应都可以促进资源丰度的空间变异性，但只有具有大平均效应大小的营养相互作用才能减少变异性。该模型的预测与重复的野外实验结果一致，并且与已发表的消费者 - 资源相互作用的数据一致，在广泛不同的环境条件和物种生活史中都证明是稳健的。因此，体现营养相互作用方差的食物网模型可能有更强的能力来解释实证研究中记录的消费者的广泛影响。
