黄土高原退耕还林工程实施后，高等维管束植物恢复的同时，生物结皮大面积发育。然而，两者共同发育下的分布格局及
空间变异却鲜有报道。通过野外调查，研究了黄土高原不同降雨量带退耕地上植被盖度、维管束植物斑块面积、个数，生物结皮
组成、盖度及其空间变化。结果表明:1)在黄土高原降水量 250—550 mm 地区的退耕地及自然荒坡上，维管束植物与生物结皮
共同存在，呈镶嵌分布。生物结皮多呈连续分布，可视为被镶嵌体，维管束植物多以斑块状存在，可视为镶嵌体。2)黄土高原
生物结皮盖度变化于 80． 8%—55． 1% 之间，在不同降雨量带之间差异显著，250—350 mm 降雨量带生物结皮平均盖度(77．
8%)显著高于 350—500 mm 降雨量带(60． 3%)，但不同类型生物结皮盖度差异显著性不同。3)黄土高原地区不同降雨量带维
管束植物冠层盖度变化于 10． 0%—58． 7%，随降雨量的增加而增加，一定程度上限制了生物结皮的发育和演替，两者表现出了
“此消彼长”的关系。4)随着降雨量的增加，高等维管束植物茎基斑块间的距离逐步减小，维管束植物覆被增加。研究结果数
量化的揭示了黄土高原不同降雨量带退耕地上维管束植物与生物结皮的镶嵌式分布格局及其空间变异特征。
其他摘要
Biological soil crusts ( biocrusts) were extensively recovered on the surface of revegetated lands after the
implementation of the“Grain for Green”Project，which is a program for retransforming croplands on steep slopes (≥25°)
into grasslands and shrublands in order to restore ecosystem functions in the Loess Plateau region． The distribution patterns
and spatial variability of biocrusts and vascular plants in the revegetated lands in this region have rarely been considered in
previous studies． The coverage，patch size，and number of vascular plants as well as biocrust cover and composition were
investigated in six successive rainfall zones ranging from 250 mm to 550 mm in the Loess Plateau region so as to determine
the distribution patterns and their spatial variation． The following observations were made from the results: 1) Ｒevegetated lands showed a mosaic pattern of vascular plants and biocrusts across the rainfall gradient． Biocrusts were mostly distributed
continuously within each site，while vascular plants often existed in patchy mosaics． 2) Biocrust coverage in different
rainfall zones in the region ranged between 55． 1% and 80． 8%． The average biocrust coverage in the 250—350 mm rainfall
zone was 77． 8%，which was significantly higher than that in the 350—500 mm rainfall zone (60． 3%)． However，no
significant difference was observed in the community composition of biocrust along this gradient． 3) Vascular plant coverage
in the region ranged from 10． 0% to 58． 7%． An obvious and significant increasing trend was observed in the coverage along
with the increase of annual mean precipitation． 4) Total and average basal patch area of vascular plants also increased along
with annual mean precipitation，while the number of individual plants decreased． Given this general trend，the smallest
plants (basal radii ＜ 0． 1 cm) dominated the plant patch-size distributions in all the rainfall zones． These results reveal the
intercorrelation of spatial pattern and distribution of biocrusts and vascular vegetation across environmental gradients in the
Loess Plateau region．
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