Altitude and landslide scale regulated the assembly of grassland communities on landslides during the recovery process after the magnitude 8.0 Wenchuan earthquake, China

Abstract

Earthquakes are one of the worst natural disasters, causing environmental fluctuations and ecosystem degradation. Previous studies have evaluated the macro-characteristics of vegetation recovery after earthquakes. However, the internal mechanisms driving community assembly and diversity remain poorly understood. This study was located in Longxi-Hongkou National Natural Reserve, China. We investigated the current vegetation status of typical large-scale landslides in regions with the highest intensity of earthquake damage in the area affected by the 2008 magnitude 8.0 earthquake, and studied the community assembly using phylogenetic methods. Relationships between community assembly and influencing factors were carried out using generalized linear models (GLMs) and redundancy analysis (RDA). Our findings suggested that the communities in areas of larger landslides were dominated by herbs 11 years after the earthquake and had not yet regenerated to the original community. The average net relatedness index (NRI) and nearest taxon index (NTI) of the communities were 0.293 and 0.482, respectively, which were higher than those of the null model. These results showed a clustered phylogenetic pattern and suggested that the community assembly process in the early regeneration stage after the earthquake supported the environmental filtering hypothesis. Altitude negatively impacted species diversity, NRI, NTI and phylogenetic diversity. This result suggested that the community assembly process was more dependent on abiotic regulation than biotic regulation at high altitudes after earthquakes. Species diversity, NRI, NTI and phylogenetic diversity were also impacted by landslide intensity; however, the responses to landslide intensity were not completely equivalent for landslides of varying widths and lengths. Slope aspect impacted the phylogenetic diversity of the regenerating community after the earthquake; that is, the sunny slopes had higher phylogenetic diversity than the shady slopes. Soil type, soil organic carbon, soil nitrogen, soil moisture, and soil phosphorous impacted community assembly. Collectively, This work showed evidence supporting the abiotic regulation of community assembly after earthquakes and reported the key abiotic influencing factors. It is important for a general understanding of community assembly after strong disturbances in temperate forests and beyond and can also provide a theoretical basis for ecological restoration engineering design.