陕北黄土区不同植被恢复模式植被与土壤耦合关系研究

Coupling relationships between vegetation and soil in different vegetation restoration models in the Loess region of Northern Shaanxi Province

植被与土壤耦合协调关系是退耕还林还草工程高效实施与可持续发展的重要依据。通过对陕北黄土区针叶纯林、阔叶纯林、针阔混交林、乔灌复层林、灌木林和天然草地6种不同植被恢复模式植被和土壤的全面调查与采样分析,建立植被与土壤耦合关系评价指标体系,综合运用层次分析法和熵权法确定各表征指标的权重,构建了不同植被恢复模式植被与土壤耦合协调度模型。结果表明:不同植被恢复模式对土壤水分和养分影响差异显著,针阔混交林的土壤环境综合评价最好,乔灌复层林最差。不同植被恢复模式的植被郁闭度、生物量、营养元素含量和生物多样性指数均存在显著差异,针阔混交林的植被群落综合评分最高,天然草地最低。土壤环境因子与植被生物量、营养元素及生物多样性密切相关。不同植被恢复模式耦合协调度依次为针阔混交林(0.767)>阔叶纯林(0.661)>天然草地(0.655)>灌木林(0.646)>针叶纯林(0.628)>乔灌复层林(0.234),其中针阔混交林为中级协调同步发展型,阔叶纯林属于初级协调同步发展型,天然草地属于初级协调植被滞后型,灌木林和针叶纯林均处于初级协调土壤滞后型,乔灌复层林则为中度失调土壤损益型。陕北黄土区植被恢复重建宜种植针阔混交林,还需加强植被抚育和土壤管理,避免配置乔灌复层林。

The coupling coordination relationship between vegetation and soil is an important basis for the efficient implementation and sustainable development of the Grain for Green Project.Based on investigations and analyses of vegetation and soil in six different vegetation restoration models(coniferous forest,hardwood forest,coniferous and broad-leaved mixed forest[theropencedrymion],arbor-shrub forest,shrubwood,and natural grassland)in the Loess region of Northern Shaanxi Province,an evaluation index system of the coupling relationship between vegetation and soil was established.The weight value of each index was determined by an analytic hierarchy process and entropy method,then models for the degree of coupling coordination between vegetation and soil were constructed.It was found that different vegetation restoration models had significantly different effects on soil moisture and nutrient contents.The comprehensive evaluations indicated that the soil environment in theropencedrymion was the best,and that in arbor-shrub forest was the worst.We detected significant differences in vegetation canopy density,biomass,nutrient element contents,and biodiversity indexes among different vegetation restoration models.The comprehensive evaluations showed that the vegetation community in theropencedrymion showed the fastest development,and that in natural grassland showed the slowest development.Soil environmental factors were significantly correlated with vegetation biomass,nutrient elements,and biodiversity.The vegetation-soil coupling coordination index of theropencedrymion,hardwood forest,natural grassland,shrubwood,coniferous forest,and arbor-shrub forest was 0.767,0.661,0.655,0.646,0.628,and 0.234,respectively.The development of vegetation and soil in theropencedrymion exhibited an intermediate synchronously coordinated type,while that in the arbor-shrub forest exhibited a moderately imbalanced soil-loss type.The vegetation-soil coupling coordination in other vegetation restoration models was at the primary coordination level.The development of vegetation and soil in hardwood forest was of a synchronous type.Vegetation development in natural grassland lagged behind soil development,while soil development lagged behind vegetation development in shrubwood and coniferous forest.Therefore,theropencedrymion should be selected preferentially for vegetation restoration and reconstruction in the Loess region of Northern Shaanxi Province,while arbor-shrub forest should be avoided.The level of vegetation and soil management should be enhanced in the Grain for Green Project.