引用本文:王彦武,罗 玲,张 峰,陈天林.河西绿洲荒漠过渡带梭梭林土壤保育效应[J].土壤学报,2019,56(3):749-762. DOI:10.11766/trxb201806260176
WANG Yanwu,LUO Ling,ZHANG Feng,CHEN Tianlin.Soil Conservation Effect of Haloxylon Ammodendron Bushes in Hexi Oasis-Desert Ecotone[J].Acta Pedologica Sinica,2019,56(3):749-762. DOI:10.11766/trxb201806260176
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河西绿洲荒漠过渡带梭梭林土壤保育效应
王彦武1, 罗 玲2, 张 峰1, 陈天林3
1.甘肃省水土保持科学研究所;2.河南理工大学资源环境学院;3.甘肃省水利厅水土保持局
摘要:
研究不同龄阶梭梭林对土壤的保护效应和复育效应的变化特征,探讨各因子之间的相互关系和梭梭林保育土壤的内在机制,可为治理河西绿洲荒漠过渡带梭梭林的土壤质量提供理论基础。在民勤绿洲荒漠过渡带采用典型抽样和空间代替时间的方法,以不同龄阶的梭梭林(20a、30a、40a)和裸沙地为研究对象,定期监测其防风固沙作用和土壤机械组成、化学性质、微生物数量及土壤酶活性变化特征,并分析了各因子的变化规律和相关关系。结果表明:梭梭林保护土壤的效应取决于梭梭林的生长情况及树龄,距离梭梭植株越近,风速逐渐减小,且背风面的减小程度大于迎风面;梭梭林中下部对风速的阻碍作用大,风速降低幅度为顶端处的1.05倍~2.04倍;随着梭梭林龄的增长,风速降低幅度的均值由12.66%增大至20.41%。各龄阶梭梭林土壤粉粒和黏粒所占比例远远小于粗砂粒和细砂粒,随土层深度增加,粉粒和黏粒含量略有减小,但均显著大于裸沙地;随着树龄增加,土壤黏粒和粉粒含量增大,粗砂粒含量减小,分别在30年时出现峰值和谷值。各龄阶梭梭林土壤的养分含量、微生物数量和酶活性各指标均表现为30年生梭梭林>40年生梭梭林>20年生梭梭林,且均为裸沙地的1.02倍以上。梭梭林土壤保育效应因子、土壤机械组成、土壤养分、微生物数量和酶活性之间均有较好的相关性,梭梭林的风速降低程度与土壤的机械组成呈极显著相关,相关系数达到了0.87以上。从梭梭林保护土壤和改良土壤效应两方面综合考虑,30年生梭梭林更适合当地生境条件,其土壤保育效果最好。
关键词:  绿洲荒漠过渡带  梭梭l林  土壤保育  复育效应  保护效应
基金项目:甘肃省青年科技基金项目(1506RJYA177);甘肃省自然科学基金项目(1308RJZA237)
Soil Conservation Effect of Haloxylon Ammodendron Bushes in Hexi Oasis-Desert Ecotone
WANG Yanwu1, LUO Ling2, ZHANG Feng1, CHEN Tianlin3
1.Gansu Institute of Soil and Water Conservation Sciences;2.College of Resource and environment, Henan Polytechnic University;3.Soil and Water Conservation Bureau, Department of Water Resources of Gansu Province
Abstract:
【Objective】In fragile ecosystems of the arid regions, soil revegetation effect is closely related to soil conservation effect. Haloxylon Ammodendron forest play a quite important role in soil quality evolution in oasis-desert ecozones by protecting and ameliorating the soil. Especially its wind-breaking and sand-fixing effects and its generation of litter, which decomposes and transforms into organic matter and soil nutrients, are the most direct external environmental factors that affect soil quality evolution the most significantly. To explore soil conserving and restoring effects ofHaloxylon Ammodendronforests, affecting factors of the effects and relationships between the factors, and internal mechanism of the effects, stands of Haloxylon Ammodendronforest different in age were selected for the study in an attempt to provide a theoretical basis for management of soil quality in the Hexi Oasis-desert Ecotone.【Methods】The paper adopted the concept of space as a substitute for time in typical sampling in the ecozone. Three stands of Haloxylon Ammodendron forest different in age (20a, 30a and 40a)’ and a tract of bare land were set for long-term monitoring and soil sampling for analysis of soil mechanical composition, chemical properties, microbial population and enzyme activity, and multiple comparisons, variance analysis and correlation analysis were used to analyze variation rules of and relationships between the factors.【Results】Results show that soil protecting effects of the forest varied with growth and age of the forest. Wind decreased gradually in speed when approaching the forest. The effect was more obvious at the lee side than at the windward side. At the height of 20 cm, 50 cm, 100 cm and 200 cm above the ground in the forest wind speed decreased by 13.75%, 14.55%, 15.0% and 7.34% or more, respectively. Obviously the wind reducing effect is higher in the middle and lower part of the forests than in the upper part, and about 1.05~2.04 times of that at the top of the plants. With the forest growing in age, the magnitude of wind reduction increased from 12.66% to 20.41%. In terms of wind reduction magnitude at the height of 20cm, 50cm and 100cm above the ground, the three stands displayed an order of stand 30 years old > stand 40 years old > stand 20 years old, but in terms of at the height of 200 cm, they exhibited a different order, i.e. stand 40 years old > stand 30 years old > stand 20 years old. In the stands of Haloxylon Ammodendron forest, regardless of age, the proportions of silt and clay were much lower that those of coarse sand and fine sand in the surface layer, and with the increase in soil depth, the contents of silt and clay decreased slightly, but were still significantly higher than that in the bare land. With the forest growing in age, the content of silt and clay increased and the content of coarse sand decreased, and both leveled off at the age of 30. The stands all peaked in nutrient content, microorganism population and enzyme activity at the age of 30, exhibiting an order of stand 30 years old > stand 40 years old > stand 20 years old, and were all over 1.02 times higher than those in the bare land. The content of soil nutrients decreased with soil depth,. The populations of soil actinomycetes and fungi and the activity of invertase was the highest in the surface soil, then in the subsoil layer and the lowest in the bottom layer. The activity of catalase and alkaline phosphatase was just in a reverse order. No obvious regularity was observed for soil bacteria in population, but good relationships were observed of the factors of the soil conservation effect of Haloxylon Ammodendronforest with soil mechanical composition, soil nutrient status, and microorganism population and enzyme activity. Wind breaking effect of the forest was significantly related to soil mechanical composition (r>0.87).【Conclusions】Considering the soil protecting and ameliorating effects of Haloxylon Ammodendronforest, the forest 30 years in stand age is the most suitable for the local habitat conditions and the highest in soil conserving effect. So in management of Haloxylon Ammodendron forests over 30 years in stand age, it is recommended to cut down trees selectively for thinning, and adopt water conserving and nutrient supplementing measures and some others so as to ensure healthy growth of the forests and enable them to keep on playing their ecological role in wind breaking and sand fixing in the ecozone.
Key words:  Oasis-desert Ecotone  Haloxylon Ammodendron forest  Soil conservation  Restoring effect  Protection effect