van Wijnen Harm J, van der Wal René, Bakker Jan P
Laboratory of Plant Ecology, University of Groningen, PO Box 14, NL-9750 AA Haren, The Netherlands e-mail:
Zoological Laboratory, University of Groningen, PO Box 14, NL-9750 AA Haren, The Netherlands, , , , , , NL.
Oecologia. 1999 Feb;118(2):225-231. doi: 10.1007/s004420050722.
Soil net N-mineralization rate was measured along a successional gradient in salt-marsh sites that were grazed by vertebrate herbivores, and in 5-year-old exclosures from which the animals were excluded. Mineralization rate was significantly higher at ungrazed than at grazed sites. In the absence of grazing, mineralization rate increased over the course of succession, whereas it remained relatively low when sites were grazed. The largest differences in mineralization rate between grazed and ungrazed sites were found at late successional stages where grazing pressure was lowest. The amount of plant litter was significantly lower at grazed sites. In addition, the amount of litter and potential litter (non-woody, live shoots) was linearly related to net N-mineralization rate. This implies that herbivores reduced mineralization rate by preventing litter accumulation. Bulk density was higher at grazed salt-marsh sites than at ungrazed sites. This factor may also have contributed to the differences in net N-mineralization rate between grazed and ungrazed sites.
在脊椎动物食草动物放牧的盐沼地以及排除动物的5年围栏区域，沿着演替梯度测量了土壤净氮矿化率。未放牧地点的矿化率显著高于放牧地点。在没有放牧的情况下，矿化率在演替过程中增加，而在放牧地点时则保持相对较低水平。放牧和未放牧地点之间矿化率的最大差异出现在放牧压力最低的演替后期阶段。放牧地点的植物凋落物量显著较低。此外，凋落物和潜在凋落物（非木质活枝条）的量与净氮矿化率呈线性相关。这意味着食草动物通过阻止凋落物积累降低了矿化率。放牧盐沼地的容重高于未放牧地点。这个因素也可能导致了放牧和未放牧地点之间净氮矿化率的差异。
