Species richness and soil properties in Pinus ponderosa forests:: A structural equation modeling analysis
Species richness and soil properties in Pinus ponderosa forests:: A structural equation modeling analysis
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DOI：
10.1658/1100-9233(2007)18
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发表时间：
2007-04-01
影响因子：
2.8
通讯作者：
Grace, James B.
中科院分区：
文献类型：
--
作者：
Laughlin, Daniel C.;Abella, Scott R.;Grace, James B.
问题：矿质土壤特性对林下植物物种丰富度的影响是如何通过一个涉及森林覆盖物、土壤有机质、土壤氮和林下植物丰富度的过程网络传播的？地点：美国亚利桑那州中北部。方法：在黄松（ponderosa）森林生态系统中，我们在广阔的土壤梯度上取样了75个0.05 ha的样地。我们利用结构方程模型评估了植物物种丰富度的多元模型。结果：在中等水平的林下植物覆盖下，物种丰富度最高，表明定殖成功和竞争排斥都限制了物种丰富度。我们没有发现丰富度对植物覆盖的相互正影响。丰富度与土壤氮在模型中有很强的相关性，既有直接的负作用，也有通过林下植物覆盖介导的间接非线性关系。土壤有机质对林下植被丰富度具有独立于土壤氮的正向影响。丰富度在林下盖度最密集的地方最低，这可以通过对土壤有机质、土壤氮和林下盖度的间接影响来解释。最后，模型结果表明，矿质土壤特性可以影响丰富度的各种直接和间接过程。结论：黄曲霉林下植物物种丰富度和植被覆盖度受土壤有机质和氮的显著影响，而土壤有机质和氮又与林下植物密度、组成和矿质土壤性质有关。因此，土壤性质对黄松林本地物种多样性具有直接和间接的制约作用。
Question: How are the effects of mineral soil properties on understory plant species richness propagated through a network of processes involving the forest overstory, soil organic matter, soil nitrogen, and understory plant abundance?Location: North-central Arizona, USA.Methods: We sampled 75 0.05-ha plots across a broad soil gradient in a Pinus ponderosa (ponderosa pine) forest ecosystem. We evaluated multivariate models of plant species richness using structural equation modeling.Results: Richness was highest at intermediate levels of understory plant cover, suggesting that both colonization success and competitive exclusion can limit richness in this system. We did not detect a reciprocal positive effect of richness on plant cover. Richness was strongly related to soil nitrogen in the model, with evidence for both a direct negative effect and an indirect non-linear relationship mediated through understory plant cover. Soil organic matter appeared to have a positive influence on understory richness that was independent of soil nitrogen. Richness was lowest where the forest overstory was densest, which can be explained through indirect effects on soil organic matter, soil nitrogen and understory cover. Finally, model results suggest a variety of direct and indirect processes whereby mineral soil properties can influence richness.Conclusions: Understory plant species richness and plant cover in P. ponderosa forests appear to be significantly influenced by soil organic matter and nitrogen, which are, in turn, related to overstory density and composition and mineral soil properties. Thus, soil properties can impose direct and indirect constraints on local species diversity in ponderosa pine forests.