Developing allometric equations to estimate forest biomass for tree species categories based on phylogenetic relationships

The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.National Forest Inventories(NFI)are detailed assessments of forest resources at national and regional levels that provide valuable data for forest biomass estimation.However,the lack of biomass allometric equations for each tree species in the NFI currently hampers the estimation of national-scale forest biomass.The main objective of this study was to develop allometric biomass regression equations for each tree species in the NFI of China based on limited biomass observations.These equations optimally grouped NFI and biomass observation species according to their phylogenetic relationships.Significant phylogenetic signals demonstrated phylogenetic conservation of the crown-to-stem biomass ratio.Based on phylogenetic relationships,we grouped and matched NFI and biomass observation species into 22 categories.Allometric biomass regression models were developed for each of these 22 species categories,and the models performed successfully(R^(2)=0.97,root mean square error(RMSE)=12.9​t·ha^(–1),relative RMSE=11.5%).Furthermore,we found that phylogeny-based models performed more effectively than wood density-based models.The results suggest that grouping species based on their phylogenetic relationships is a reliable approach for the development and selection of accurate allometric equations.

Spatiotemporal analysis of the impact of urban landscape forms on PM_(2.5) in China from 2001 to 2020

Urban landscape forms can be effective in reducing increasing PM_(2.5) concentrations due to urbanization in China,making it crucially important to accurately quantify the spatiotemporal impact of urban landscape forms on PM_(2.5) variations.Three landscape indices and six control variables were selected to assess these impacts in 362 Chinese cities during different time scales from 2001 to 2020,using a spatiotemporal geographically weighted regression model,random forest models and partial dependence plots.The results show that there are spatiotemporal differences in the impacts of landscape indices on PM_(2.5).the proportion of urban green infrastructure(PLAND-UGI)and the fractal dimension of urban green infrastructure(FRACT-UGI)exacerbate PM_(2.5) concentrations in the northwest,the proportion of impervious surfaces(PLAND-Impervious)mitigates air pollution in northwest and southwest China,and shannon’s diversity index(SHDI)has seasonal differences in the northwest.PLAND-UGI is the landscape index with the largest contribution(30%)and interpretable range.The relationship between FRACT and PM_(2.5) was more complex than for other landscape indices.The results of this study contribute to a deeper understanding of the spatial and temporal differences in the impact of urban landscape patterns on PM_(2.5),contributing to clean urban development and sustainable development.

How urbanization affect the ecosystem health of Tibet based on terrain gradients:a case study of Shannan,China

Urbanization has significant impacts on ecosystem health(ESH)by affecting land-use patterns.The evaluation of the ESH and the spatial correlations between human interference provides an insight into sustainable development as a response to potential ecological degradation if ESH is threatened by further urbanization.We applied the Vigor-Organization-Resilience-Services(VORS)modelto detect the responses of ESH of Shannan Prefecture in the Tibet to urbanization from 1990 to 2015,based on different levels of terrain gradients.The results show that the ESH of the most areas in Shannan reaches the levels of highest health and average health during the study period.By 2015,the area proportion at the highest health level increased by 0.68%,while that of degraded level decreased by 1.51%.Overall,the ESH of areas tends to shrink at higher-level TGs,and urban sprawl with ESH shrinking existed in middle-level TGs in Shannan.Furthermore,a significant spatial aggregation effect was found concerning that low ESH-high CUL type is mainly distributed on the middle-level TGs with dense human population.The results highlight the needs to rationally organize urbanization process in plateau regions based on different TGs,which contribute to maintain ESH advancing people livelihood improvement.