Forest dynamics of a subtropical monsoon forest in Dinghushan, China: recruitment, mortality and the pace of community change

Abstract

Abstract:Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005–2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest.

Inferring community assembly processes from trait diversity across environmental gradients

“…In this situation, competitive interactions will exclude all but the tallest species, and then drive clustering. This may occur in specific regions of a homogeneous habitat where niche differences are not significant, but may not occur in a community with complicated habitats such as the DHS plot (Shen et al 2013, Wang et al 2009). …”

“…The 20-ha DHS plot was established in the core of the DHS Natural Reserve in 2005(Bin et al 2012. All stems with a diameter at breast height (dbh) ࣙ1 cm were measured, mapped and tagged in the initial census (Shen et al 2013). A total of 178 species and 61,125 individuals were recorded in the second census in 2010.…”

“…At each point, we collected 500 g of topsoil (0-10 cm depth) and analysed nine soil properties: organic matter (OM; mg g −1 ), soil pH, water content (WC, %), total potassium (TK; mg g −1 ), available potassium (AK; mg g −1 ), total nitrogen (TN; mg g −1 ), available nitrogen (AN; mg g −1 ), total phosphorus (TP; mg g −1 ) and available phosphorus (AP; mg g −1 ) (Lin et al 2013). Soil values for each 20 × 20-m quadrat were calculated using kriging methods.…”

Determinants of change in subtropical tree diameter growth with ontogenetic stage

“…relative growth rate of stem diameter (rgr; cm cm −1 year −1 ) was calculated as (log(DBH t )−log(DBH o ))/t, where DBh o and DBh t represent DBh at the first and last census, respectively (Poorter et al 2008). Calculations of rgr were done only for species that had at least 20 individuals in each size class during the initial census (Poorter et al 2008;shen et al 2013), resulting in 57 and 29 species for saplings and large trees, respectively.…”

Dynamics and Prediction of Diametric Structure in Two Atlantic Forest Fragments in Northeastern Brazil

“…As Shen et al (2013) reported, this distribution can suggest recruitment stability, whereas bell-shaped distributions indicate a decline or lack of recruitment. However, different distribution shapes can also appear from different forest typologies (SHEN et al, 2013).…”