Search Results (4)

Forest thinning is a widely used silvicultural method in forest management and has complex effects on carbon sequestration in different types of forest ecosystems. The present study examined the short-term effects of different thinning intensities on carbon storage in an 11-year-old mixed broadleaved plantation. The results partially supported that different thinning intensities have varying impacts on carbon storage in different parts of forest ecosystems. The main results were as follows: (1) The effect of thinning on promoting the growth of fast-growing tree species (Michelia macclurei Dandy and Schima superba Gardn. et Champ.) was earlier than that of slow-growing tree species (Castanopsis hystrix Miq.). (2) A greater thinning intensity conferred greater effects on promoting the tree biomass carbon growth, litter carbon storage, and understory plant diversity, in the order of 41%~50% > 31%~40% > 20%~30%, but these values were lower than those for the unthinned plots. (3) The soil carbon storage declined most in the 41%~50% thinned plots, due to the reduced carbon storage in the humus layer. (4) The 20%~30% thinning intensity promoted carbon sequestration in the short term in the mixed broadleaved plantation. The results suggested that a lower thinning intensity promoted carbon sequestration in the short term, a greater thinning intensity reduced carbon storage at first, but the negative effect on carbon storage exhibited trade-offs later by the growth of tree and understory plant biomass carbon and the accumulation of litter layer carbon. Full article

The soil profile is a strong and complex physicochemical gradient that greatly affects bacterial community structure and function between soil layers. However, little is known about molecular ecological network structure and bacterial community function under differing soil profiles in planted forests. Four typical native tree species (Pinus massoniana Lamb., Castanopsis hystrix Miq., Mytilaria laosensis Lec., and Michelia macclurei Dandy) plantations were selected from subtropical China as the research object. We evaluated molecular ecological network structure as well as potential function of the soil bacterial community at different soil depths (0–20, 20–40, and 40–60 cm) within native tree plantations. Our results showed that (1) compared to the topsoil (0–20 cm), the bacterial molecular ecological network scale increased within the middle layer (20–40 cm) and the subsoil (40–60 cm), and the interaction between species was stronger; (2) module hubs and connectors were the key bacterial groups in each soil layer and increased with increasing soil depth; (3) the dominant functional groups of the bacterial communities in each soil layer were chemoheterotrophy, aerobic chemoheterotrophy, cellulolysis, ureolysis, nitrogen fixation, and nitrate reduction, and they were related to soil carbon and nitrogen cycling; and (4) the different molecular ecological network structures along with relative bacterial functional group abundances among diverse soil layers were mainly affected by soil organic carbon (SOC), NO₃⁻-N, NH₄⁺-N, available phosphorus (AP), and total phosphorus (TP). Our study provides a theoretical foundation for bacterial community structure together with function within soil profiles of native tree plantations in subtropical regions. Full article

Climate warming poses a great threat to ecosystems worldwide, which significantly affects the geographical distribution and suitable growth area of species. Taking Castanopsis hystrix Miq. as the research object, the potentially suitable cultivation regions under present and future climatic emission scenarios in China were predicted based on the MaxEnt model with 360 effective individual distributions and eight environmental variables. The min temperature of coldest month (bio6), precipitation of driest month (bio14), and precipitation of warmest quarter (bio18) are three leading factors affecting the geographical distribution area of C. hystrix Miq. The suitable cultivation regions of C. hystrix Miq. range from 18°–34° N, 89°–122° E in central and southern China and cover an area of 261.95 × 10⁴ km². The spatial pattern of C. hystrix Miq. will migrate to the southern region of low latitudes with a decreasing suitable area when in ssp1-2.6, and to the southwestern region of low latitudes or expand to the northeast region at high latitudes in ssp5-8.5, with an increasing suitable area; no significant change on the spatial pattern in ssp2-2.4. For ssp1-2.6 or ssp2-4.5 climate scenarios, the southern region of high latitudes will be appropriate for introducing and cultivating C. hystrix Miq., and the cultivation area will increase. For ssp5-8.5, its cultivation will increase and expand to the northeast of high-latitude areas slightly. Full article

Although the advantages of multi-species plantations over single-species plantations have been widely recognized, the mechanisms driving these advantages remain unclear. In this study, we compared stand biomass, litter production and quality, soil properties, soil microbial community, and functions in a Pinus massoniana Lamb. and Castanopsis hystrix Miq. mixed plantation and their corresponding mono-specific plantations after 34 years afforestation in subtropical China. The results have shown that a coniferous-broadleaf mixture created significantly positive effects on stand biomass, litter production, soil microbial biomass, and activities. Firstly, the tree, shrub and herb biomass, and litter production were significantly higher in the coniferous-broadleaf mixed plantation. Secondly, although the concentrations of soil organic carbon (SOC) and total nitrogen (TN) were lower in the mixed stand, the concentrations of soil microbial biomass carbon (MBC), and nitrogen (MBN), along with MBC-to-SOC and MBN-to-TN ratio, were significantly higher in mixed stands with markedly positive admixing effects. We also found higher carbon source utilization ability and β−1, 4−N−acetylglucosaminidase, urease and acid phosphatase activities in mixed stands compared with the mono-species stands. Our results highlight that establishment of coniferous-broadleaf mixed forests may be a good management practice as coniferous-broadleaf mixture could accumulate higher stand biomass and return more litter, resulting in increasing soil microbial biomass and related functions for the long term in subtropical China. Full article