Landscape Effects on Local Species Richness of Woody Specialists in Subtropical Montane Cloud Forest of Taiwan

Aim

How is the local species richness of woody specialists in vegetation plots located within subtropical montane cloud forests (SMCFs) affected by the landscape structure of the surrounding SMCF habitat patch?

Location

Subtropical montane cloud forests in Taiwan.

Taxon

Woody species specialised in growing in foggy conditions.

Methods

We used plant occurrence data from major herbaria together with fog frequency data to identify fog specialists of SMCFs in Taiwan. Subsequently, we extracted 20 × 20 m forest vegetation plots from the National Vegetation Database of Taiwan and calculated the richness of woody specialists in each of them. Using a published predicted SMCFs distribution map, we estimated the landscape context of SMCFs around each vegetation plot within circular buffer zones of increasing radius. The variables of landscape structure include those related to the area of SMCFs habitat (area and connectivity), surrounding heterogeneity (topographical heterogeneity and vegetation diversity) and edge effect (the nearest distance from the plot to the edge and the edge length). The multiple linear regression model was used to investigate which of the three mechanisms of landscape context has the strongest effect on the local richness of fog specialists.

Results

Only the area of SMCFs habitat patch shows a significant positive effect on the local species richness of woody specialists in the plot when considering all the landscape variables. Area per se might be a possible mechanism that supports this positive species-area relationship. Additionally, the area of SMCFs patch is highly correlated with connectivity, indicating that larger SMCF patches enhance connectivity beyond buffer zones, sustaining species through the rescue effect from the regional species pool.

Main Conclusions

Patch size and connectivity are crucial for the species richness of woody specialists in SMCFs in Taiwan. For conservation, we recommend protecting larger, less fragmented SMCF patches to maintain biodiversity.