Vertical heterogeneity of a forest floor invertebrate food web as indicated by stable-isotope analysis
Vertical heterogeneity of a forest floor invertebrate food web as indicated by stable-isotope analysis
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DOI：
10.1007/s11284-009-0619-0
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发表时间：
2009-11-01
影响因子：
2
通讯作者：
Sota, Teiji
中科院分区：
文献类型：
--
作者：
Okuzaki, Yutaka;Tayasu, Ichiro;Sota, Teiji
不同种群的无脊椎动物构成了森林地面碎屑层的食物网。在这样一个物种丰富的群落食物网中，营养相互作用的异质性可能会影响生物群落的动态特性，如稳定性。为了研究枯落物和腐殖质层中无脊椎动物之间营养相互作用的垂直异质性，我们研究了物种组成的差异和碳和氮稳定同位素比值（δ（13）C和δ（15）N）的变化，使用日本温带阔叶林的森林地面的全群落指标。这两个层之间的物种组成不同，和无脊椎动物在凋落物层一般大于那些在腐殖质层，这表明这些层窝藏基于不同的基础资源的独立的食物网。然而，三角洲（13）C的无脊椎动物，社区食物网的基础资源的差异的指标，并没有提供证据，层之间的独立的食物网，即使植物源有机质显示出不同的稳定同位素比根据分解状态。无脊椎动物的最小三角洲（15）N也没有不同的层之间，这表明在较低的营养水平的两层食草动物的食物共享。最大和范围内的三角洲（15）N在腐殖质层更大，表明更多的营养转移（可能涉及微生物）比在凋落物层，并提供间接证据弱营养层之间的相互作用在较高的营养水平。因此，无脊椎动物群落食物网并没有明确划分碎屑层之间，但仍表现出显着的空间（垂直）异质性的营养相互作用。
Diverse populations of invertebrates constitute the food web in detritus layers of a forest floor. Heterogeneity in trophic interactions within such a species-rich community food web may affect the dynamic properties of biological communities such as stability. To examine the vertical heterogeneity in trophic interactions among invertebrates in litter and humus layers, we studied differences in species composition and variations in carbon and nitrogen stable-isotope ratios (delta(13)C and delta(15)N) using community-wide metrics of the forest floors of temperate broadleaf forests in Japan. The species composition differed between the two layers, and the invertebrates in the litter layer were generally larger than those in the humus layer, suggesting that these layers harbored separate food webs based on different basal resources. However, the delta(13)C of invertebrates, an indicator of differences in the basal resources of community food webs, did not provide evidence for separate food webs between layers even though plant-derived organic matter showed differences in stable-isotope ratios according to decomposition state. The minimum delta(15)N of invertebrates also did not differ between layers, suggesting sharing of food by detritivores from the two layers at lower trophic levels. The maximum and range of delta(15)N were greater in the humus layer, suggesting more trophic transfers (probably involving microorganisms) than in the litter layer and providing circumstantial evidence for weak trophic interactions between layers at higher trophic levels. Thus, the invertebrate community food web was not clearly compartmentalized between the detrital layers but still showed a conspicuous spatial (vertical) heterogeneity in trophic interactions.