ENVIRONMENTAL PATCHINESS AND THE BREAKDOWN OF LEAF LITTER IN A WOODLAND STREAM

ENVIRONMENTAL PATCHINESS AND THE BREAKDOWN OF LEAF LITTER IN A WOODLAND STREAM
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林地溪流中的环境斑块和落叶分解

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发表时间：
1974
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通讯作者：
S. R. Reice
S. R. Reice
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文献类型：
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作者：
S. R. Reice

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林地溪流中外来凋落物的分解过程发生在群落水平上，呈斑块状分布。测试了两种环境斑块：底沉积物类型和叶包大小。研究了沿平行环境梯度（流速和沉积物复杂性）排列的四种沉积物：岩石、砾石、沙子和淤泥。研究了五种包装尺寸：1、5、10、20和40克。将预先称重的白灰（美洲黄曲柳）传单捆在砖块上，放在沉积物上。每周取样6周，测定干重损失的百分比。每个季节都采用这种设计来测试凋落叶分解的季节变异性。方差分析和均值比较表明，在所有季节，沉积物和种群大小的影响都非常显著（P < .001）。各种大小的叶包在淤泥中比在其他沉积物中被分解得少。沉积物格局与群落水平的物理异质性和稳定性效应相一致。尽管不同季节的叶包大小效应变化很大，但每个季节的叶包大小的破坏程度不同，至少有一种叶包大小与其他叶包大小存在较大差异。击穿的季节特征反映了温度的依赖性，击穿随温度的升高而增加。群落级凋落叶分解过程在空间上呈斑片状分布。这表明种群和群落之间存在一定程度的组织，即特定于斑块的组成群落。
The breakdown of allochthonous leaf litter in woodland streams occurs at the community level process which is patchily distributed. Two kinds of environmental patches were tested: types of bottom sediment and sizes of leaf pack. Four sediments, aligned along parallel environmental gradients (velocity and sediment complexity), were studied: rock, gravel, sand, and silt. Five pack sizes were studied: 1, 5, 10, 20, and 40 g. Preweighed packs of white ash (Fraxinus americana) leaflets were tied to bricks and set on the sediments. These were sampled weekly for 6 wk, and the percent dry weight lost was determined. This design was followed in each of the four seasons to test the seasonal variability in leaf litter breakdown. Analysis of variance and comparison of means show that, in all seasons, sediment and pack—size effects are highly significant (P < .001). Leaf packs of all sizes were broken down less in the silt than in the other sediments. The sediment patterns are consistent with the community level effects of physical heterogeneity and stability. Though the pack—size effects were highly variable from season to season, the degree of breakdown differentiated the leaf—pack sizes in every season, at least one size displaying major differences from the others. The seasonal patterns in breakdown reflect its temperature dependence, the breakdown increasing with increasing temperature. The community level process of leaf litter breakdown in streams is patchily distributed in space. This suggests a level of organization between the population and the community, namely the patch—specific component community.