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Typhoons are having an increasingly severe and widespread impact on forest ecosystems around the world due to climate change. However, few studies have examined the impacts of strong typhoons on subtropical evergreen broadleaved forests, particularly in rare old-growth forests. Here, using a 20 ha permanent subtropical forest plot in Guangdong Province, southern China, the impact of super Typhoon Mangkhut on secondary and old-growth subtropical evergreen broadleaved forests was quantitatively investigated and compared. The old-growth forest was damaged more than twice as much as the secondary forest, as measured by the proportion of the basal area of damaged trees. Forest structure and composition played a significant role in determining the vulnerability of forests to powerful typhoons. This study advances knowledge about how old-growth forests respond to global climate change.

Soil microbes re-establish plant diversity and ecosystem functions after disturbance events. Deterministic and stochastic processes are expected to contribute to microbial community assembly during long-term ecosystem recovery. We characterized soil prokaryotic and fungal communities, to determine their assembly patterns, along two chronosequences with early to later successional subtropical forests. Prokaryotic and fungal community composition was more variable in early successional forests but converged in the later successional forests. The community composition was governed by deterministic processes in the early stages, while the relative influence of stochasticity increased in the later stages. Environmental factors that predicted the shift in deterministic and stochastic balance varied within and across successional stages. In particular, the compositional dissimilarity of plant communities strongly predicted the relative influences of the two processes during succession. These findings suggest that the relative influences of deterministic and stochastic processes in shaping microbial community assembly shift during secondary succession. Consequently, plant communities are important predictors of assembly processes in soil microbial communities during long-term ecosystem recovery.

Topography is an important environmental feature that affects the spatial genetic structures of plant species. However, its influence on such structures at small spatial scales has hardly been investigated for forest tree species even though many of them are located in mountains with complex topographic features. Here we report the genetic structures of a pioneer species, Castanopsis chinensis (Fagaceae), in a 20-ha forest plot in Dinghushan in lower subtropical China, which has complex topographic features, such as valleys and ridges. C. chinensis typically undergoes wind pollination, but its seeds are dispersed by gravity and animals. Therefore, the mechanisms of transportation of its seeds may result in topography-dependent genetic structures, whereas wind-mediated pollen flow of C. chinensis may reduce such structures through counteracting the influence of topography. Our results indicate that most of the genetic patterns in C. chinensis in our study plot were attributable to wind-mediated pollen flow. However, we also found both seed and pollen flows could be impeded by ridges, causing some varied genetic patterns even between locations separated by only small distances. We observed that owing to topographic positions where they grew, the 13 old individuals that were probably the oldest in the southeast corner of the plot had not made major genetic contributions to the young individuals that had recently colonised previously clear-cut land in the rest of the plot. Therefore, our results indicate that we should consider both species life-history traits and topography when studying the genetic structures of plant populations in order to design sound conservation and management programs for the areas with complex topography.

Habitat specialization has been considered as a primary factor in determining the distribution of species. In this study, we investigated species–habitat associations while controlling for spatial neighbourhood effects in a large-scale (20 ha) stem-mapping plot in a species-rich subtropical forest of China. Habitat specialization was measured by topographic variation and its effects on species distributions were modelled at three different spatial scales (10×10, 20×20 and 25×25 m2) using log-linear regression models and randomization tests. Our results showed: (1) 83% of the species were related to at least one or more topographic variables. Among them, 66%, 60%, 65% and 70% were closely dependent on slope, aspect, elevation and convexity, respectively. (2) Topographic variables have much stronger non-linear (quadratic and cubic) effects on species distributions than linear effects. (3) The effects of topographic heterogeneity on the distribution of shrubs species are smaller than on the distribution of canopy species, and smaller effects were also found in less abundant species. (4) There was a strong neighbourhood effect on species distribution: In 85% of the species, abundance in a focal quadrat was significantly correlated with abundance in the neighbour quadrats. We conclude that habitat specialization plays an important role in maintaining the diversity of this species-rich subtropical forest.