Impacts of Cwd on Understory Biodiversity in Forest Ecosystems in the Qinling Mountains, China

The stocks and characteristics of coarse woody debris (CWD) are expected to reflect forest stand features. However, despite their importance, there have been no reports of CWD stocks and characteristics in the Qinling Mountains. We measured the CWD stocks in different CWD types, decay classes and diameter classes of the five forest types in the Qinling Mountains. The highest biomass of CWD was the Pinus tabulaeformis forest (12.57 t·hm), occupied 5.66% in the biomass of this forest, the lowest occupied 1.03% in Betula albo-sinensis forest (1.82 t·hm). Our results revealed that there was a strong correlation between CWD and forest biomass. When the CWD biomass were 9.9 t·hm and 11.6 t·hm, the biomass of Pinus armandi forest and P. tabulaeformis forest reached maximum, respectively. CWD is particularly important for biodiversity, but the importance of CWD in the control of diversity in forest systems has not been fully appreciated and certainly has not been evaluated intensively within China, especially in Qinling forests. In our research, we used species richness (S), Shannon-Wiener index (H), Simpson index (D) and Pielous evenness index (J) to assess the diversity of plant community. According to our analysis, we found 1) the effect of CWD biomass onthese α diversity index was dependent on tree, shrub and herb in the five forest types, 2) the impacts of CWD biomass on understory biodiversity were more obvious, 3) With the increase of CWD biomass, the species richness (S), Shannon-Wiener index (H) and Simpson index (D) of understory increased significantly. Our results suggested that there was a relatively lower CWD biomass in the Qinling Mountains, but it had significant effects on forest biomass and diversity of plant community. Reserving CWD was important for eco-forestry, but how many and how characteristic of CWD should be retained need further research. Development of CWD reasonable strategies was indispensable for future forest management.