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| 1 | 全球原木贸易网络格局演变与中国地位变迁显示文摘【目的】厘清全球原木贸易网络的动态演化特征,为各国(地区)原木贸易决策提供参考。【方法】运用社会网络分析方法,从全局、局部和个体3个层面,对2000—2018年全球原木贸易网络的结构特征和格局演变进行分析,并从网络地位和贸易模式两个方面探讨中国在全球原木贸易网络中的地位变迁。【结果】研究结果表明,全球原木贸易网络规模不断拓展,网络内部贸易关系稀疏程度相对平稳,但平均贸易额上升明显。不同年份全球原木贸易网络的板块构成不同,板块内部联系趋于紧密,核心国家(地区)趋于“抱团”,但板块间联系逐渐减少,板块间“俱乐部”效应显著下降。不同国家(地区)的核心度变化趋势不同,中国、印度等国家(地区)核心度上升明显,中国于2011年超越美国,居于核心度首位,而美国、俄罗斯、法国等国家(地区)核心度则呈下降趋势;中国个体网络规模不断提升,“桥”的作用明显,但结构洞效应有所弱化。原木产业内贸易规模不断提升,贸易伙伴以“边缘型”国家(地区)为主。贸易逆差不断减小,进口依存度有所提升。【结论】各国(地区)应根据自身和整体网络特征,采取各种措施优化原木贸易网络,推动国际物流互联互通,优化贸易路线,减少运费成本,提高运输效率,为高效、便利、低成本的原木贸易营造良好的外部环境。中国作为原木需求最为旺盛的国家,要根据自身实际,采取有效措施提升自身在全球原木贸易网络中的话语权,不断优化原木贸易网络,降低对单个国家(地区)的进口依赖,维护国内木材安全。 | 周莹莹 程宝栋 尤薇佳 郑文迪 | 2021 | 中南林业科技大学学报2021，41，12： | 3 |
| 2 | Management scheme influence and nitrogen addition effects on soil CO_(2),CH_(4),and N_(2)O fluxes in a Moso bamboo plantation显示文摘Background:It is still not clear whether the effects of N deposition on soil greenhouse gas(GHG)emissions are influenced by plantation management schemes.A field experiment was conducted to investigate the effects of conventional management(CM)versus intensive management(IM),in combination with simulated N deposition levels of control(ambient N deposition),30 kg N·ha^(−1)·year^(−1)(N30,ambient+30 kg N·ha^(−1)·year^(−1)),60 kg N·ha^(−1)·year^(−1)(N60,ambient+60 kg N·ha^(−1)·year^(−1)),or 90 kg N·ha^(−1)·year^(−1)(N90,ambient+90 kg N·ha^(−1)·year^(−1))on soil CO_(2),CH_(4),and N_(2)O fluxes.For this,24 plots were set up in a Moso bamboo(Phyllostachys edulis)plantation from January 2013 to December 2015.Gas samples were collected monthly from January 2015 to December 2015.Results:Compared with CM,IM significantly increased soil CO_(2) emissions and their temperature sensitivity(Q_(10))but had no significant effects on soil CH_(4) uptake or N_(2)O emissions.In the CM plots,N30 and N60 significantly increased soil CO_(2) emissions,while N60 and N90 significantly increased soil N_(2)O emissions.In the IM plots,N30 and N60 significantly increased soil CO_(2) and N_(2)O emissions,while N60 and N90 significantly decreased soil CH_(4) uptake.Overall,in both CM and IM plots,N30 and N60 significantly increased global warming potentials,whereas N90 did not significantly affect global warming potential.However,N addition significantly decreased the Q_(10) value of soil CO_(2) emissions under IM but not under CM.Soil microbial biomass carbon was significantly and positively correlated with soil CO_(2) and N_(2)O emissions but significantly and negatively correlated with soil CH_(4) uptake.Conclusion:Our results indicate that management scheme effects should be considered when assessing the effect of atmospheric N deposition on GHG emissions in bamboo plantations. | Junbo Zhang Quan Li Jianhua Lv Changhui Peng Zhikang Gu Lianghua Qi Xuzhong Song Xinzhang Song | 2021 | Forest Ecosystems2021，8，1： | 2 |
| 3 | 基于地基激光雷达估测广西桉树人工林的林分参数显示文摘以地面实测数据为对照,应用地基激光雷达技术对广西国有高峰林场2,5,10 a生桉树(Eucalyptus)人工林进行扫描,评估了地基激光雷达对单木识别和单木参数提取的能力,并进一步探讨其对林分参数提取的可行性。结果显示:1)地基激光雷达对桉树人工林的单木识别能力较强,总体识别率达93.45%,提取的各类单木参数在不同林龄间均存在显著差异(P<0.05),与实测趋势相一致。2)在2 a生桉树人工林中,地基激光雷达估测的单木胸径值、胸高断面积值、单木材积值与实测值均无差异。同时发现,基于地基激光雷达结合AdQSM重建林木模型的方法是可行的,其与通过立木材积模型计算的结果呈现极显著的线性相关(P<0.01,R^(2)=0.96,MAE=0.05m^(3))。3)在林分水平上,地基激光雷达对林分平均胸径、平均树高、林分断面积、单位蓄积量的估测精度分别为94.69%,93.75%,89.66%,84.22%,具有较优的估测能力。研究表明,应用地基激光雷达可以在样地尺度上快速估测桉树人工林的林分参数。 | 谢贤胜 苏宏新 杨元征 李春海 卢峰 罗蔚生 徐占勇 | 2022 | 林业资源管理2022，，2： | 1 |
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