分类： 农、林、牧、渔 >> 林学 提交时间： 2024-02-21 合作期刊: 《干旱区科学》
摘要： Tree plantation and forest restoration are the major strategies for enhancing terrestrial carbon sequestration and mitigating climate change. The Grain for Green Project in China has positively impacted global carbon sequestration and the trend towards fragmentation of plantation forests. Limited studies have been conducted on changes in plantation biomass and stand structure caused by fragmentation, and the effect of fragmentation on the carbon storage of plantation forests remains unclear. This study evaluated the differences between carbon storage and stand structure in black locust forests in fragmented and continuous landscape in the Ansai District, China and discussed the effects of ecological significance of four landscape indices on carbon storage and tree density. We used structural equation modelling to explore the direct and indirect effects of fragmentation, edge, abiotic factors, and stand structure on above-ground carbon storage. Diameter at breast height (DBH) in fragmented forests was 53.3% thicker, tree density was 40.9% lower, and carbon storage was 49.8% higher than those in continuous forests; for all given DBH>10 cm, the trees in fragmented forests were shorter than those in continuous forests. The patch area had a negative impact on carbon storage, i.e., the higher the degree of fragmentation, the lower the density of the tree; and fragmentation and distance to edge (DTE) directly increased canopy coverage. However, canopy coverage directly decreased carbon storage, and fragmentation directly increased carbon storage and tree density. In non-commercial forests, fragmentation reduces the carbon storage potential of plantation, and the influence of patch area, edge, and patchy connection on plantation should be considered when follow-up trees are planted and for the plantation management. Thus, expanding the area of plantation patches, repairing the edges of complex-shaped patches, enhancing the connectivity of similar patches, and applying nutrients to plantation forests at regular intervals are recommended in fragmented areas of the Loess Plateau.
分类： 农、林、牧、渔 >> 林学 提交时间： 2022-07-18 合作期刊: 《干旱区科学》
摘要： The study of the heterogeneity of soil enzyme activities at different sampling locations in canopy gaps will help understand the influence mechanism of canopy gaps on soil ecological processes. In this paper, we analyzed the spatiotemporal variation of soil enzyme activities and soil physicochemical properties at different sampling locations (closed canopy, expanded edge, canopy edge, gap center) in different sampling time (December, February, April, June, August, and October) on the northern slope of the Tianshan Mountains, Northwest China. The results showed that soil catalase, cellulase, sucrase, and acid phosphatase activities were relatively high from June to October and low from December to April, and most of soil enzyme activities were higher at closed canopy than at gap center. Soil urease activity was high during DecemberFebruary. The soil temperature reached the highest value during JuneAugust and was relatively high at gap center in October, December, and February. Soil water content was significantly higher in December and April than in other months. Soil bulk density was higher at gap center than at closed canopy in December. Soil pH and soil electrical conductivity in most months were higher at closed canopy than at gap center. Soil organic carbon, soil total nitrogen, and soil total phosphorus were generally higher at gap center than at closed canopy. Furthermore, sampling time played a leading role in the dynamic change of soil enzyme activity. The key factors affecting soil enzyme activity were soil temperature and soil water content, which were governed by canopy gaps. These results provide important support for further understanding the influence mechanism of forest ecosystem management and conservation on the Tianshan Mountains.
分类： 农、林、牧、渔 >> 林学 提交时间： 2020-01-13
摘要： 本文从学科科学的基本观点,分析了过去100多年来化学、化工、生物化学等基础学科对森林植物资源化学利用理论和技术发展的影响，阐述了林产化学加工学科的起源、形成和发展历程。在此基础上，提出现代林产化学加工工程学科是以森林植物资源为研究对象，以化学和生物化学为学科基础，合成和制备生物质新能源、化学品和功能材料的理论知识、方法和技术体系。最后，论文讨论了现代林产化学加工工程学科在理论知识和技术上面临的主要挑战。
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