The Variation of Species Diversity, Regeneration and Community Structure in Larix gmelinii Forest Shaping by Local Environment Factors

Abstract Inner Mongolia Hanma National Nature Reserve without human disturbance is a natural laboratory for the study of Larix gmelinii forest because it has well-preserved coniferous forests in cold temperate zone in Northeast China. Fifty-eight plots were set up in nature reserve to examine the most important local environment factors involved in spatial distribution of Larix gmelinii forest communities. Based on field investigation, there were 5 association groups in Larix gmelinii forest including Community I (Larix gmelinii-Betula platyphylla-Vaccinium vitis-idaea+ Ledum palustre), Community II (Larix gmelinii-Pinus pumila-Vaccinium vitis-idaea), Community III (Larix gmelinii-Rhododendron dauricum-Vaccinium vitis-idaea), Community IV (Larix gmelinii-Vaccinium vitis-idaea+ Ledum palustre), Community V (Larix gmelinii-Betula fruticosa-Ledum palustre). Larix gmelinii in Community IV has larger Diameter at breast height of trees and relatively little regeneration seedlings. The content of soil total carbon, soil total nitrogen and soil total phosphorus in Community III reached highest value among all the association groups. Species richness showed significantly negative correlation with elevation and slope, meanwhile, positive correlation with soil total phosphorus. Species evenness showed significantly positive correlation with elevation and slope, meanwhile, significantly negative correlation with soil total nitrogen and phosphorus. Redundancy analysis showed a better explanation for vegetation distribution pattern and indicated that elevation, slope, soil pH and aspect played significant roles in community assembly. The study provided a reference for Larix gmelinii forest ecosystem protection and a theoretical basis for scientific management in similar areas.