Analysis of Productivity Influencing Factors in Chamaecyparis pisifera Communities in Caoyutang National Forest Park of Shexiang, Zhejiang Province

Studying the ecological characteristics such as community structure, net productivity, and the response to soil nutrients of different density Chamaecyparis pisifera communities is beneficial for elucidating the ecological processes and functional mechanisms of forest ecosystems. Based on growth data and soil chemical properties from C. pisifera plots of varying densities in Caoyutang National Forest Park of Shexiang, Zhejiang Province, collected in 2013 and 2023, this study compared biomass and net productivity, conducted model tests using the subset regression method, and explored the key factors influencing net productivity. The results indicate that: （1） The mean diameter at breast height （DBH） of low-density C. pisifera stands （750 trees/ha） increased by approximately 6.1 cm from 2013 to 2023, while the mean tree height increased by about 4.0 m. For high-density C. pisifera stands （1 850 trees/ha）, the mean DBH increased by approximately 5.8 cm, and the mean tree height increased by about 8.6 m during the same period. The DBH growth was similar between different densities, while tree height increased faster in high-density C. pisifera stands. （2） The mean aboveground biomass of low-density C. pisifera stands was 462.8±28.7 kg in 2013 and 721.1±26.4 kg in 2023. For high-density stands, it was 99.1±12.3 kg in 2013 and 279.3±21.6 kg in 2023. The net productivity of low-density C. pisifera stands was greater compared to high-density stands. （3） Soil organic matter, available potassium, and available phosphorus significantly influenced the growth and productivity improvement of high-density C. pisifera communities, while soil pH, total phosphorus, and total potassium content favored the growth and productivity improvement of low-density C. pisifera communities. Through studying the growth patterns and influencing factors of C. pisifera communities, scientific basis can be provided for forestry management, guiding rational vegetation restoration, protection, and sustainable utilization of forest resources, thereby promoting the sustainable development of forestry.