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半干旱地区生物结皮通过降低土壤水分导致了人工灌木的退化和死亡

已有 3915 次阅读 2017-1-16 14:53 |系统分类:科研笔记

The relationships between biocrusts andshrubs in semiarid areas, are of great importance, however, not yet sufficientlyinvestigated. It is unknown whether or not biocrusts will decrease soilmoisture and result in the degradation of artificially planted shrubs insemiarid climates. In a semiarid watershed on the Loess Plateau of China, weselected 18 sampling sites in artificial shrublands and measured at each thesoil moisture from 0 to 200 cm depth under bare land, moss-dominated biocrusts,artificially planted Artemisia ordosica, A. ordosica with biocrusts, and dead A.ordosica with biocrusts. We also estimated the water-holding capacity and infiltrabilityof the soil with and without biocrusts. The A. ordosica with biocrusts had24.4% lower biomass and 18.9% lower leaf area index than those withoutbiocrusts, suggesting negative effects of biocrusts on these shrubs. Moreover, thebiocrusts underneath A. ordosica decreased soil moisture 14.8% on average (2.6%vs. 3.1%; p b 0.01) due to their significant higher water-holding capacity (21.6%) and lower infiltrability (50.4%), compared to the area withoutbiocrusts. Most importantly, the area with biocrusts and dead A. ordosica hadsimilar soil moisture to the area with biocrusts and live A. ordosica,suggesting that the decreased soil moisture under the biocrusts persists afterthe death of A. ordosica. Our results suggest that biocrusts reduce soil waterresources available to the artificially planted shrubs, thus increasing therisks of shrubmortality and further land degradation. The high coverage ofmoss-dominated biocrusts appears to be a dominant factor in soil moisturevariations in artificial shrublands under semiarid climates, making the soilwater balance more vulnerable in this region.


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上一篇:Biological Soil Crusts: An Organizing Principle in Drylands
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