晋西北丘陵风沙区坡面尺度下不同固沙植物群落稳定性分析

Stability Evaluation of Different Sand-fixing Plant Communities in Hilly Sandy Area of Northwest Shanxi

人工固沙植被群落的稳定是评价干旱半干旱风沙区植被恢复成功的重要标准。该研究运用模糊综合评判理论,对晋西北丘陵风沙区坡面尺度下(坡上、坡中、坡下)7种人工固沙优势植物的稳定性进行分析,选取优势植物生长状况、土壤质量、林下植物生物量和多样性以及Godron指数4项指标,通过计算其隶属度平均值来评价植物的稳定性。结果表明:(1)乔木油松枝叶生物量最大(1457.1 g),灌木柠条枝叶生物量最大(1429.1 g),各优势植物坡下枝叶生物量最大。(2)灌木表层(0~20 cm)土壤水分优于各乔木表层土壤水分,同时不同植物林均表现出坡下土壤水分最大;各植物表层土壤有机质、解碱氮、速效钾、速效磷基本都远高于撂荒地,其中乔木油松和灌木柠条各土壤养分指标显著高于其他植物,且不同植物林下养分也表现为坡下最优。(3)林下植物生物量乔木青杨最大(87.2 g),灌木柠条最大(50.4 g),坡下生物量最大;林下植物丰富度指数乔木青杨最高,林下植物多样性指数和均匀度指数乔木樟子松和油松最高,灌木中林下植物各多样性指数基本相近。(4)Godron指数:乔木中刺槐的交点坐标离群落稳定点最近,灌木中柠条交点坐标离群落稳定点最近。综合各指标的隶属度平均值得到乔木稳定性指数排序为:油松(0.69)>刺槐(0.67)>青杨(0.66)>樟子松(0.39)>旱柳(0.28),灌木稳定性排序为:柠条(0.82)>紫穗槐(0.64),乔灌木植物稳定性均远高于撂荒地(0.20)。研究认为乔木油松和灌木柠条稳定性最高,是西北丘陵风沙区适宜的造林树种,而坡下则是更优的种植坡位选择。该研究结果可为晋西北丘陵风沙区域以至于黄土高原人工固沙植被恢复和科学管理提供依据。

The stability of artificial sand-fixing vegetation community is an important criterion to evaluate the success of vegetation restoration in arid and semi-arid sandy areas.In this paper,we used the fuzzy comprehensive evaluation theory to evaluate the stability of seven dominant plants of artificial sand fixation at the slope scale(upslope,midslope and downslope)in the wind-sand area of northwestern Shanxi Province.The growth status of dominant plants,soil quality,biomass and diversity of understory plants and Godron index were selected to evaluate the stability of plants by calculating the average membership degree.The results showed that:(1)the biomass of branches and leaves of Pinus tabuliformis in trees was the largest(1457.1 g),the biomass of branches and leaves of Caragana korshinskii in shrubs was the largest(1429.1 g),and the biomass of branches and leaves of dominant plants was the largest under slope.(2)The soil moisture of shrub surface layer(0-20 cm)was better than that of tree surface layer,and different plant forests showed the largest soil moisture under slope.The soil organic matter,alkali-hydrolyzable nitrogen,available potassium and available phosphorus in the surface soil of each plant were much higher than those in the abandoned land.The soil nutrient indexes of P.tabuliformis and C.korshinskii were significantly higher than those of other plants,and the nutrients under different plants were also the best in the slope.(3)The biomass of understory plants:Populus cathayana tree was the largest(87.2 g),C.korshinskii shrub was the largest(50.4 g),and the biomass of slope was the largest.The richness index of understory plants in tree was the highest in P.cathayana,the diversity index and evenness index of understory plants in tree were the highest in Pinus sylvestris and P.tabuliformis,and the diversity index of understory plants in shrubs was basically similar.(4)Godron index:the intersection coordinates of Robinia pseudoacacia in trees were closest to the community stability point,and the intersection coordinates of C.korshinskii in shrubs were closest to the community stability point.Based on the average membership of each index,the order of tree stability index was as follows:P.tabuliformis(0.69)>R.pseudoacacia(0.67)>P.cathayana(0.66)>P.sylvestris(0.39)>Salix matsudana(0.28).The order of shrub stability was as follows:Caragana microphylla(0.82)>Amorpha fruticosa(0.64).The stability of trees and shrubs was much higher than that of abandoned land(0.20).As a whole,P.tabuliformis tree and C.korshinskii shrub have the highest stability,which are suitable for afforestation.Downhill is a better choice of slope position.This study can provide a basis for the restoration and scientific management of artificial sand-fixing vegetation in the wind-sand area of northwestern Shanxi and the Loess Plateau.