Despite the influence of cavities on the survival and distribution of cavity-dependent fauna, the variation in the density and characteristics of tree cavities across different habitat types in tropical forests is unknown. In this study, we surveyed 26â312 living trees from 376 species and compared cavity density and characteristics (height, size, type, and orientation) across five habitat types (valley, low-slope, high-slope, high-gully, and high-plateau) in a 20-hectare tropical rainforest in southwest China. From a total of 2047 cavities, we found that cavity density was mainly driven by habitat rather than tree species richness or diameter at breast height (DBH), and the characteristics of cavities were not uniformly distributed across habitats. Cavities were significantly more abundant in high- and low-slope than high-plateau habitats. Compared with other habitats, more âbutt hollowâ cavity types were found in high-slope habitat and they occurred at a lower tree height, whereas more âcrackâ cavities were found in low-slope habitat and they had a narrower entrance diameter. Although the mean orientation of cavities faced towards the northeast, cavity orientation varied significantly across habitat types. Our results indicate that certain types of cavities are concentrated in specific habitat types, which can provide avenues for forest management and biodiversity conservation. We highlight the importance of habitat heterogeneity in providing resources for cavity nesters.
In tropical forests, trees often have damage in the form of visible cavities. However, the impacts of these cavities on tropical tree growth and survival are unknown, despite potential implications for the global carbon cycle. Here, we integrate 10 years of forest dynamics data with a survey of cavity presence on 25,450 rainforest trees (> 5 cm in diameter) in the 20 ha Xishuangbanna plot in southern China. We found that cavities negatively impacted tree growth, but not survival, with the growth of smaller trees more negatively affected by cavities. Variation in the impact of cavities was not explained by functional traits related to species life history strategy (specific leaf area, wood density, seed mass, leaf %N, leaf %P). These results suggest that cavities may affect both the compositional and carbon dynamics of tropical forests, but further research is needed to determine what drives variation amongst tree species in cavity impact.
Landscape aesthetic quality (LAQ) is a vital cultural ecosystem service in global forests, particularly in the subalpine forests across the Tibetan Plateau, which are considered popular tourist destinations due to their unique cultural services. However, the explicit spatial localization and spatial–temporal dynamics of LAQ in subalpine forests in the Tibetan Plateau remain largely unexplored. Herein, we introduced a method for assessing LAQ that integrates the species’ biophysical attributes with spatial landscape characteristics, allowing for a spatially explicit quantification of LAQ. We further employ this approach to project changes in LAQ under forest landscape dynamics (2016–2096) in Jiuzhaigou, eastern Tibetan Plateau. Most regions exhibited moderate or low LAQ, with high values ible, while over half of low-LAQ regions were not. The high-value zone of LAQ is projected to rise slightly by 2056 but decline sharply by 2096. These results reveal strong spatial heterogeneity in LAQ and indicate that future landscape dynamics will substantially reshape its distribution in the subalpine forests of the eastern Tibetan Plateau. Our findings provide early evidence of declining cultural ecosystem quality in subalpine forests and offer guidance for adaptive management in similar mountain ecosystems worldwide.