Adaptability evaluation and resource strategy of community dominant species in the process of vegetation restoration in karst area of Guizhou

【Objective】This paper studied the strategies of plant light,temperature and water environmental resources and their changing rules in the process of vegetation restoration in karst area,with a view to providing theoretical basis for vegetation nourishment management in the region. 【Method】This paper took the karst vegetation in Maolan National Nature Reserve in Guizhou as the research object,used spatial substitution time method and plant functional traits as the entry point,analyzed the adaptive trait change process of community dominant species during the restoration process from grass-shrub community stage to shrub community stage to arbor-shrub community stage,and combined principal component analysis and membership function method to evaluate the light,temperature,and water adaptability of 18 community dominant species during the vegetation restoration process; by analyzing the changes in the adaptive evaluation value(D) of dominant species,the resource strategy of dominant species was elucidated,and the K-means method was used to divide the adaptive functional groups,in order to reveal the structural changes and countermeasures of functional groups during vegetation restoration. 【Result】Among the light adaptation traits of the dominant species in the community,chlorophyll a content(1.213-1.851 mg/g),chlorophyll a/b(2.321-2.994) decreased and then increased with vegetation restoration,and specific leaf area(125.491-215.580 cm²/g) gradually decreased with vegetation restoration; among the water adaptation traits,leaf dry matter content(0.272-0.386),leaf tissue density(0.060-0.151 g/cm³) gradually increased with vegetation restoration,and leaf relative water content(0.671%-0.840%) decreased and then increased with vegetation restoration; among the temperature adaptation traits,malonaldehyde content(39.116-63.162 nmol/g) decreased and then increased with vegetation restoration,and catalase activity117.555-1618.869 nmol/(g·min) gradually increased with vegetation restoration. Principal component analysis showed that D_light reflected the absorption range of light wavelengths and the strength of light resource conversion rate of the dominant species,D_temperature reflected the tolerance level of the dominant species to peroxidation produced by extreme temperature stress,and D_water reflected the ability of the dominant species to maintain normal growth under drought conditions; as vegetation restoration proceeded,D_light of the dominant species of the community showed a trend of decreasing and then increasing,D_watergradually increased from 0.428 to 0.612,D_temperature did not differ greatly among the restoration stages,and the dominant species of the community changed from an open light resource acquisition strategy to a conservative water resource competition strategy. In this paper,three functional groups were classified based on D,namely FG1(low light-low temperature-low water adaptation functional group),FG2(high light-high temperature-high water adaptation functional group) and FG3(low light-low temperature-high water adaptation functional group);the percentage of important values for FG1 gradually decreased with vegetation restoration,reaching the highest value(49.275%) in the grass-shrub community stage and 36.931% in the shrub community stage,whereas no species of this resource type existed in the arbor-shrub community stage; the species of FG2 existed in the grass-shrub and arbor-shrub community stages only and their percentage of important values was small; the percentage of important values for FG3 gradually increased with vegetation restoration. 【Conclusion】Species with low photosynthetic rate,low light resource capture area,and intolerance to water and heat stress dominate in the early stages of recovery;since the shrub community stage,it has gradually been replaced by species with low photosynthetic rate,low light resource capture area,intolerance to extreme temperatures and drought tolerance. Vegetation nurturing in karst areas should retain light resource acquisition strategy species in the early stages of restoration,with multiple resource strategy species coexisting,and mainly retain water resource competition strategy species in the middle and later stages of restoration.