Wood density, growth and mortality relationships of lianas on environmental gradients in fragmented forests of montane landscapes

Aim A better understanding of plant communities can be achieved by incorporating data of traits and dynamics into surveys. Wood density is a good predictor for growth and mortality in trees, but to date, no studies of lianas include all three. We examine how liana communities respond to environmental gradients and forest fragmentation in terms of abundance, diversity, size structure, mortality, relative growth rate and wood density, and tested how the latter three are related to each other in liana species. Location Xishuangbanna, SW China. Methods We repeated a survey of lianas (stems >0.5 cm diameter) in 47 plots, distributed in forest fragments of various size, on different bedrock (limestone or sandstone), over an elevational range and across different topographic elements (ridge, slope, valley). We gathered wood density data for 116 of 166 species, covering 90% of all surveyed stems. We also determined relative growth rate, mortality, stem diameter and basal area. Results At the species level, liana mortality and relative growth rate were lower at higher wood density, and mortality was higher with greater relative growth rate. At the plot level, liana communities in valleys had high relative growth and mortality rates as well as high abundance and diversity. Forest on limestone hosted few species but more large-stemmed liana individuals, and communities had higher wood density weighted by basal area. Liana abundance, relative growth rates and mortality were greater and average wood density lower towards fragment edges, but the explanatory power of these models was low. Conclusion Habitat was the major factor shaping liana communities, whereas fragmentation was not an important predictor in our study. Resource-rich environments such as valleys harbour diverse liana communities with high mortality and relative growth rates. This pattern matches earlier studies on survival/growth trade-offs among plant species. The relationship between growth rates, mortality and wood density in lianas follows the same trade-offs as found in trees.