| Naiman Banner is located in the southern edge of Horqin Sandy Land,is the key area of "Three North" shelterbelt construction project.As a typical representative of semi-arid farming-pastoral ecotone,a large area of Populus artificial shelterbelt has been built in this area since 1970 s.However,due to the unreasonable planting density and structure,a large area of low-yield and low-efficiency forest has been formed by Populus trees.Based on this,this paper adopted the method of field investigation and experimental measurement to analyze the stand growth status,inter-zone plant community characteristics soil physical and chemical properties and their correlation of four kinds of Populus simonii shelterbelts in Naiman Banner with the same site conditions and similar stand ages(19-24a).The coupling relationship between vegetation and soil system was studied by mathematical analysis method.The aim is to provide reference for scientific afforestation and management of Naiman Banner plantation.Specific research results are as follows:(1)The characteristics of tree height,DBH and crown diameter of Populus simonii shelterbelt were 10 m > 6m > 4m > 2m,and the canopy density was opposite.A total of17 herbaceous species were found in various areas,belonging to 8 families and 14 genera.Compositae,gramineae,chenopodium and legumes accounted for 76.47%.Interzone species richness,biomass and diversity index showed that grassland > 10 m >6m > 4m > 2m > wilderness,and vegetation community of 10 m shelter forest gradually developed to zonal vegetation.Band spacing was positively correlated with tree height and crown diameter(p < 0.05),negatively correlated with stand canopy closure,and positively correlated with tree DBH,inter-band diversity index and biomass(p < 0.01).(2)Interzone soil water content,capillary porosity,non-capillary porosity,total porosity,organic carbon,alkali-hydrostatic nitrogen,available phosphorus,available potassium,total nitrogen and total phosphorus were in the order of grassland > 10 m >6m > 4m > 2m > wilderness.Soil bulk density: grassland < 10 m < 6m < 4m < 2m <wilderness;Field water capacity: 10 m > 6m > 4m > 2m > grassland > wilderness;Soil p H: wilderness > grassland > 2m > 4m > 6m > 10m;The bulk density and water content increased with the deepening of soil layer,while the field water capacity,porosity and soil chemical properties decreased with the deepening of soil layer.The effect of belt spacing on soil total K was not obvious.The zone spacing was negatively correlated with soil bulk density.It was positively correlated with water content and field capacity.The zone spacing of 40-60 cm soil layer was significantly correlated with soil chemical properties,in which soil p H was negatively correlated,while other chemical properties were positively correlated(p < 0.05).(3)Vegetation index and soil index showed significant positive and negative correlation at different soil depths(p < 0.05).Margalef richness index was the vegetation community characteristic index with the highest correlation degree with soil p Hysicochemical properties,and soil bulk density was the soil index with the highest correlation degree with vegetation community characteristic index.(4)The coupling coordination degree obtained by principal component analysis and entropy weight method is 10 m > 6m > 4m > 2m;The results were as follows: 10 m shelter forest was barely coordinated and synchronized,6m shelter forest was endangered and disregulated vegetation loss,4m shelter forest was endangered and disregulated co-lost,2m shelter forest was mildly disregulated co-lost,10 m shelter forest was the best in coupling coordination degree between plant and soil system. |
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