浙江省大气PM2.5时空分布及相关因子分析

该研究以浙江省2014-2019年PM_2.5浓度数据为研究对象,应用多元线性回归和随机森林方法结合气象、植被、地形、经济、人口和基础设施等因子进行分析.研究结果表明PM_2.5浓度时空分布不均匀,时间上季节变化差异显著,总体呈冬季>春季>秋季>夏季分布规律,每年呈下降趋势;空间上呈西北多东南少的分布特征.多元线性回归和随机森林模型显示日最低地表气温（MI-GST）、日最低气压（MI-PRS）、日蒸发量（EVP）、日最小相对湿度（MI-RHU）、月植被覆盖度（FVC）、日降水量（PRE）、日极大风速（MM-WIN）、日平均相对湿度（AV-RHU）、铁路密度（Railway）、日最大风速（MA-WIN）、日照时长（SSD）、海拔（DEM）、日平均风速（AV-WIN）和河流密度（River）等15个因子对PM_2.5浓度影响显著;随机森林模型均方根误差（RMSE）、均方绝对百分比误差（MAPE）和变异解释量（R²）分别为0.133、17.83%和0.834,明显优于多元线性回归（0.278、40.48%和0.575）,表明随机森林更适合浙江省PM_2.5浓度估测,该研究揭示PM_2.5时空分布及相关因子分析,为限制空气污染提供有效策略.     

基于典型相关系数和随机森林的水质预警方法

针对突发水污染事件提出一种高精度的预警方法.首先,通过模拟实验建立包含22种常见污染物的突发水污染事件数据库,然后采用典型相关系数准确揭示污染事件发生后多元水质参数之间的协同反馈规律.最后,基于多参数协同反馈规律构建“典型相关系数-随机森林”水质预警模型.结果表明预警模型对已知和未知污染物的平均准报率分别为96.78%和98.33%,对水质监测基线的平均误报率为0.16%.本研究成果可为降低突发水污染事件损失和保障供水安全提供有效的技术支撑.     

基于价值取向的城市森林游憩服务需求研究

在调查南京城市森林游憩者的基础上,以森林价值取向为预测变量,对城市森林游憩服务需求进行了研究.研究表明,市民的森林价值取向包括生态取向、健康取向、文化取向、产品取向和消极取向五种类型;城市森林游憩服务需求则包括基本需求、拓展需求和个性需求三个层次.通过典型相关分析发现,对森林资源持“健康”、“文化”和“生态”价值取向的市民对森林游憩的“基本服务”需求明显,更重视森林的自然和文化环境保护;而持有“产品”和“消极”取向的市民,则希望森林游憩地能提供更多“拓展”和“个性”服务.在此基础上,提出了积极引导城市森林游憩者的政策建议.     

修正的BP神经网络森林火灾成灾面积预测研究

以1997-2012年《中国林业统计年鉴》的全国森林火灾成灾面积为依据,应用BP神经网络模型对成灾面积进行了预测,对预测方法进行了检验.在此基础上,利用残差提出了修正的BP神经网络模型,并对预测方法进行了改进.研究结果表明,修正的BP神经网络预测精度高于BP神经网络,预测相对误差平均为7.2％,可应用于森林火灾成灾面积的预测.     

黄土丘陵区人工刺槐林土壤有机碳矿化特征及其与有机碳组分的关系

为了探讨黄土丘陵区人工林有机碳矿化特征及有机碳组分变化规律,选择恢复13 a的人工刺槐林以及临近坡耕地为研究对象,开展3种不同温度处理(15、25和35℃)下的室内培养实验.结果表明,土壤有机碳矿化速率表现出先剧烈下降后平稳的趋势;有机碳累计释放量表现为培养初期增加迅速,后期逐渐缓慢;坡耕地土壤有机碳矿化对温度的变化更为敏感,其温度敏感性系数Q₁₀为1.52,而刺槐林地仅为1.38.通过单库一级动力学方程拟合可知刺槐林地和坡耕地土壤矿化潜力C_p分别在2.02～4.32g·kg^-1和1.25～3.17g·kg^-1之间,即刺槐林的矿化潜力更高.培养期内各种活性有机碳组分含量变化规律一致,均表现为随时间延长而下降,且刺槐林地大于坡耕地,土壤累计碳释放量与MBC和DOC含量均呈显著正相关关系(P<0.05),Q₁₀(15～25℃)与SOC、 EOC含量和SWC均呈线性关系(P<0.05).研究结果可为气候变化下黄土丘陵区土壤碳固存研究提供一定参考.     

Extending the EU Renewable Energy Directive sustainability criteria to solid bioenergy from forests

Solid bioenergy from forests plays — and is expected to continue to play — a key role to fulfil the renewable energy targets at the European Union level. When the Renewable Energy Directive was enacted, sustainability criteria were incorporated solely for biofuels and bioliquids. Sustainability criteria for solid bioenergy are also needed in order to prevent wood and primary forest residues from posing additional environmental risks to ecosystems. Acknowledging this, the European Commission has been working on extending the biofuels and bioliquids provisions to solid biomass. An internal draft was circulated in August 2013 which addressed the ways to both balance and mitigate the risks in three main topics: biodiversity; sustainable forest management; and greenhouse gases. This paper presents a set of criteria and indicators, developed during workshops with experts from Governments, scientific institutions, businesses and NGOs, that may be considered by the EU to assure that solid biomass from forests is obtained in an environmentally sustainable way.     

短期氮添加对黄山松林土壤碳组分的影响及其微生物机制

人类活动和大气沉降增加了陆地生态系统氮的输入,显著改变了生态系统碳循环.为了更好地理解氮沉降如何调节森林土壤有机碳组分动态,及其潜在的微生物机制.本研究在福建戴云山黄山松林设置3个氮添加梯度（对照（0 kg·hm^-2·a^-1）、低氮（40 kg·hm^-2·a^-1）、高氮（80 kg·hm^-2·a^-1） ）以模拟氮沉降.通过测定土壤基本理化性质、土壤微生物生物量、酶活性和碳利用效率,利用两步硫酸水解法将土壤有机碳分为量小、周转快的活性碳组分和量大、周转慢的惰性碳组分,以探究两年氮添加对亚热带黄山松土壤有机碳组分的影响.与对照相比,氮添加显著降低0~10 cm土壤活性碳组分含量,增加土壤惰性碳含量.氮添加提高了参与碳、氮和磷获取的3种水解酶活性（β-葡萄糖苷酶、β-N-乙酰氨基酸葡糖苷酶、酸性磷酸单酯酶）,并显著降低了土壤微生物碳利用效率.冗余分析和随机森林模型表明,土壤微生物碳利用效率、微生物生物量和β-葡萄糖苷酶是影响土壤碳组分变化的主要因子,且土壤微生物碳利用效率与活性碳呈显著正相关,与惰性碳呈显著负相关;微生物生物量碳与活性碳呈显著正相关,与惰性碳无显著关系.综上所述,土壤微生物生物量减少、碳利用效率的下降导致活性碳组分含量减少,而惰性碳组分含量增加,进而提高黄山松林土壤有机碳的稳定性.     

基于高光谱遥感的镉污染潜在风险估算

为探究高光谱遥感快速监测镉污染的可行性,本文利用2002年以来农田土壤重金属镉实测数据,镉的标准原子光谱曲线数据,HSI(Hyperspectral Imaging Radiometer)高光谱遥感卫星数据,选取长江流域10个地区作为研究区,基于随机森林法估算镉污染的潜在风险空间分布值。结果表明:通过原子标准光谱曲线选择特征波段是可行的,能够极大简化特征波段选取流程;随机森林法具有估算土壤重金属镉含量的能力,预测准确度较高;长江流域镉污染超标问题普遍存在,大部分研究区超标率高于8%,其中上游地区镉污染较中下游地区更为严重,上游研究区镉污染超标率均大于20%。     

Mercury accumulation and dynamics in montane forests along an elevation gradient in Southwest China

Understanding atmospheric mercury (Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon (C), and nitrogen (N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C (from 237.0 ± 171.4 to 56.8 ± 27.7 µg/kg) and Hg/N (from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest (244.9 ± 55.7 µg/kg) and the lowest value in the alpine forest (151.9 ± 44.5 µg/kg). Further analysis suggests that soil Hg is positively correlated to C (r² = 0.66) and N (r² = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.     

Synergies and trade-offs among integrated conservation approaches in Mexico

Integrated conservation approaches (ICAs) are employed by governments, communities, and nongovernmental organizations worldwide seeking to achieve outcomes with dual benefits for biodiversity conservation and poverty alleviation. Although ICAs are frequently implemented concurrently, interactions among ICAs and the synergies or trade-offs that result are rarely considered during program design, implementation, and evaluation. In support of more deliberate and effective use of ICAs, we examined interactions among four well-known strategies: biosphere reserves (BRs), voluntary protected areas (VPAs), payments for ecosystem services (PES), and community forest management (CFM). Through a comparative case study, we analyzed interactions among spatially or temporally clustered ICAs implemented on communally held and managed lands in three ecologically and socioeconomically distinct regions of Mexico. Our research methods combined policy analysis with data gathered through participant observation and semistructured interviews (n = 78) and focus groups (n = 5) with government officials, implementers, and participants involved in ICAs in 28 communities. Despite the significant differences among the regions in which they were implemented, we found that key actors at each level of involvement generally perceived interactions among ICAs as synergistic. The PES programs were perceived to strengthen protected areas by reducing forest cover loss in and around BRs, fostering proconservation attitudes, and incentivizing the establishment of VPAs. Communities that invested PES income in CFM were motivated to conserve forests beyond the duration of PES programs, and CFM in buffer zones was perceived to strengthen BRs by maintaining forest cover and generating income for communities. We also identified key social and environmental factors that can influence these interaction effects among ICAs. Based on these findings, we recommend further study of ICA interactions and intentionally complementary policy design to maximize positive environmental and social outcomes.