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

Abstract

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.

Leaf and Stem Traits are Linked to Liana Growth Rate in a Subtropical Cloud Forest

“…Across 11 lianas studied, RGR was not correlated with wood density (Figure 5b), consistent with a report on lianas in Barro Colorado Island, Panama [9]. However, there was a significantly negative correlation between the relative growth rate and wood density among lianas in a montane forest in SW China [10]. Strong leaf and stem water transport capacities are usually positively linked with high growth rates among trees [27].…”

“…To date, it is still an open question as to whether plant traits are strongly linked with their growth rate [2][3][4][5]. The majority of previous studies about plant trait-growth patterns have focused on trees [2][3][4][6][7][8], with fewer reports concerning lianas [9,10]. It is, therefore, of importance to unveil how the growth rate of lianas is driven by their interspecific variation in plant traits.…”

“…For instance, Putz (1990) reported that the correlation between the rate of diameter increment and wood density was non-significant across 15 liana species on Barro Colorado Island, Panama [9]. However, a significantly negative correlation was found between the relative growth rate and wood density among lianas in a montane forest in southwest (SW) China [10]. It is imperative to include more studies from diverse forest ecosystems to unveil the liana growth-trait patterns.…”

On tree longevity

“…The oldest individuals are those that remain suppressed in the understory during their initial development, thereby accumulating smaller increments and slower growth histories (Figs 5, 7). Reduced growth rates, starting from the earliest ontogenetic stages, can then be viewed as a necessary condition for attaining maximum tree longevity, not just for trees (Bigler & Veblen, 2009) but also for lianas (Roeder et al ., 2019).…”

The ecology of a liana community in a SW Chinese rainforest: functional traits, dynamics, and distribution

“…The lack of consensus about large-scale patterns in liana change and its possible drivers urges for additional studies on lianas dynamics covering a wider geographic range (Gerolamo et al 2018). Here, we focus on liana community dynamics in a tropical seasonal rainforest in an understudied region (Asia, but see Wright et al 2015, Roeder et al 2019) and global biodiversity hotspot (Myers et al 2000).…”