The influence of fire on rodent abundance at the N’washitshumbe enclosure site,Kruger National Park,South Africa

The relative population numbers of rodents were studied in nine habitats in and outside the N’washitshumbe enclosure site, Kruger National Park, before and after burning the firebreaks that surround the enclosure. Trap success was exceptionally high, and the field work is suspected to have coincided with a Mastomys population explosion. This genus dominated the small mammal communities before and after the burn, and never disappeared from the burnt patches. Its numbers also did not crash directly after the burn, as have been reported in most other studies. Movement from the burnt areas was observed, which may have had a significant impact on the numbers of rodents caught both inside the enclosure and in the more natural areas outside. Our study suggests that fire can be investigated as a tool to keep rodent densities down in areas where they are nuisance animals, especially when used in conjunction with models that forecast outbreaks of Mastomys. It also emphasizes the value of long-term studies informing management strategies for animal damage control and biodiversity and ecosystem conservation.     

Factors Affecting Agroforestry Sustainability in Bee Endemic Parts of Southeastern Nigeria

ABSTRACT

This paper attempts, in an exploratory manner, to identify the various ways in which unsustainable beekeeping and honey hunting practices result in the loss of important multi-purpose agroforestry tree species in bee endemic parts of Southeastern Nigeria. Both qualitative and quantitative approaches (Rapid Rural Appraisal (RRA), community fora, focus group discussions, key informant interviews, and semi-structured interview schedules) were used in an interactive manner to collect data for this study from five randomly selected communities in Nsukka, Igbo-Etiti, Uzo-Uwani, Igbo-Eze South and Udenu Local Government Areas of Enugu State. Results show that beekeeping/honey hunting in the area is traditionally gender-specific occupations involving only male members of the households, while female members play an active role in processing, preserving, and marketing the products. The majority (69.6%) of the beekeepers/ honey hunters were within the age range of 31–50, and most (75.2%) of them did not receive secondary school education. Findings reveal that outright felling of some trees in order to extract honey, cutting tree trunks open and/or cutting down tree branches and setting surrounding bush on fire are among the major factors negatively impacting on the agroforestry of the area. Species of trees particularly at risk include Irvingia gabonensis, young Chlorophera excelsa, Raphia spp., Elaeis guineensis, Brachystegia eurycome, Dialium guineense, Erythrophleum guineese and Strychnos spinosa. Recommendations are proffered to improve harvesting practices for hive and other non-timber forest products in order to avert the erosion of natural resource base of the fragile farming ecosystem of the area.     

Legal Mechanisms for Addressing Wartime Damage to Tropical Forests

Summary

The tactics of war have profound impacts on tropical forest ecosystems, and modern weapons technologies have greatly increased their destructive potential. Some legal protection is afforded by customary international law, and the international community responded to the Vietnam War by adopting, inter alia, the 1977 Additional Protocol I to the Geneva Conventions and the 1976 Environmental Modification Convention, which prohibit “long-term” (or “long-lasting”), “widespread,” and “severe” environmental damage. Nevertheless, many regard these and other existing conventions as inadequate, especially as applied to internal conflicts. More recently, the International Union for the Conservation of Nature-World Conservation Union (IUCN) put forth a Draft Convention on the Prohibition of Hostile Military Activities in Internationally Protected Areas. This paper analyzes the IUCN Draft Convention-particularly issues of prior designation of protected areas, waiver of protection, and monitoring and enforcement-and compares it to other relevant area-based treaties, such as the 1954 Hague Convention for the Protection of Cultural Property and the 1972 World Heritage Convention. The paper also highlights other recent legal developments that may help prevent, remediate, or punish wartime damage to tropical forests, such as the nascent International Criminal Court; liability mechanisms for providing compensation for wartime damage; environmental guidelines for military, peacekeeping and humanitarian operations; import bans and trade embargoes; and a proposed no-fault remediation fund.     

充填采煤技术在解决煤矿中敏感环境问题的应用探讨

指出了充填采煤技术作为一项绿色环保采煤技术已经在国内煤矿中有较多应用,通过充填开采不仅能减缓采煤地表下沉对地面环境的破坏程度,同时可以消耗大量煤矸石、粉煤灰等固体废弃物,减少固体废弃物对土地资源的占用。近些年来,水源地、城镇村庄、土地资源和河流等重要敏感环境问题与煤矿建设的冲突日益突出,以矿区环境影响评价为例,对充填采煤技术在解决煤矿环境制约因素问题的应用进行了探讨。     

浅谈西部环境法律体系建设与完善

指出了为适应深入实施西部大开发的发展战略,加强西部地区的生态建设,要求建立与完善与其相适应的环境法律法规。从西部环境保护的法律体系现状出发,分析了现有环保法律体系的不足。同时,从自然和社会两方面提出了完善现在法律体系的措施,并强调了国家机关、社会组织、公民的监督的作用。     

高速公路建设造成的水土流失影响及减缓措施

指出了公路工程项目属于建设性项目,穿越地形地貌复杂多样,扰动地表程度及形式复杂多变,对沿线水土流失影响较大。以高速公路环境影响评价为例,对公路建设造成的水土流失影响进行了分析和阐述,提出了可采取的减缓措施。     

铅冶炼的环境风险评价研究

指出了铅冶炼过程中的环境风险具有复杂性、隐蔽性等特点,容易被人忽视,根据多年的研究成果和实践经验,对其涉及的环境风险性物质、环境风险产生的环节、环境风险产生的机理和危害、环境风险的防范措施进行了系统的研究,针对不同环节、不同环境风险物质,提出了科学实用的风险防范措施,以期能有效地解决铅冶炼的环境风险问题,确保环境安全。     

三元复合驱采油污水对水丝蚓DNA损伤的影响

[目的]研究三元复合驱采油污水对水生动物基因的毒性效应。[方法]以霍甫水丝蚓(Limnodrilu hoffmeisteri)为受试生物,以浓度分别为12%、36%、24%和44%的采油污水稀释液为供试污染物,采用碱性单细胞凝胶电泳实验,以尾长(TL)、头部DNA含量(HeadDNA)和尾部DNA含量(Tail DNA)为指标检测不同浓度采油污水对水丝蚓DNA的损伤程度。[结果]三元复合驱采油污水会引起水丝蚓体细胞DNA损失,暴露组中受试生物的头部DNA含量与对照组相比均显著减少(P<0.05),尾长和尾部DNA含量均显著升高(P<0.05),随着采油污水浓度的增加,DNA损伤表现出明显的"剂量-效应"关系。[结论]该研究表明三元复合驱采油污水对水丝蚓具有基因毒性效应,可能对油田生态环境产生严重影响。     

基于XGBoost-ANN的城市绿地净碳交换模拟与特征响应

为分析城市绿地净生态系统碳交换(Net ecosystem exchange,NEE)对环境因子的响应,利用涡度相关法测量了2013—2016年生长季白天的NEE数据,使用XGBoost以及ANN模型对NEE进行模拟和分析,并通过决定系数(R~2)、平均绝对误差(MAE)、均方根误差(RMSE)和一致性系数(IA) 4个指标评价模拟精度。结果表明,当输入因子为光合有效辐射(PAR)、饱和水汽压差(VPD)、空气温度(Ta)、相对湿度(RH)、土壤温度(Ts)、风速(WS)、10 cm处土壤含水率(VWC10)时,模拟效果达到最优。其训练集精度R~2为0. 712,RMSE为4. 394μmol/(m~2·s),MAE为3. 129μmol/(m~2·s),IA为0. 911;测试集精度R~2为0. 748,RMSE为4. 253μmol/(m~2·s),MAE为2. 971μmol/(m~2·s),IA为0. 920。在考虑因子间相互作用后,环境因子对NEE的重要性排序从大到小依次为PAR、VPD、Ta、RH、Ts、WS、VWC10;就单环境因子而言,对NEE的重要性由大到小依次为Ta、Ts、RH。通过计算生态系统净生产力(Net ecosystem productivity,NEP,即-NEE)对主要环境因子(PAR、VPD、Ta)的偏导数可知,生态系统光合作用表观量子效率最大值为0. 087,并且当PAR大于1 200μmol/(m~2·s)时,其不再是影响光合作用的主要因素; VPD偏导数的变化趋势表明,VPD对植物光合作用的影响以抑制性为主,当VPD过大时,偏导数趋近于0,此时植物叶片气孔闭合,抑制光合作用; Ta偏导数的变化趋势说明,随着温度的升高,光合作用速率逐渐大于呼吸作用的速率。研究表明,基于XGBoost与ANN模型能够更为精确地模拟NEE动态,在相关环境因子中,PAR、VPD、Ta是影响NEE变化的主导因子,NEE对主要影响因子的生态特征响应趋势可为理解碳循环关键过程提供参考。     

基于流变特性分析的菠菜有序收获机夹持输送装置研究

针对菠菜有序收获夹持输送过程中极易出现挤压损伤的问题,基于菠菜植株的流变特性对夹持输送过程中工作参数对损伤的影响进行了研究。首先提出了一种菠菜夹持输送装置,阐述其工作原理和机械结构,分析了浮动夹持机构与菠菜植株的互作关系;通过Burgers粘弹性模型构建了菠菜植株夹持输送作用下的流变本构方程,利用菠菜植株的蠕变试验,确定流变本构方程系数;在不考虑弹性变形和粘塑性变形前提下求得菠菜塑性变形表达式,并将菠菜塑性变形量作为衡量菠菜机械损伤程度的评价指标;选择对损伤影响较大的夹持轮当量弹性系数和输送速度,分析其对菠菜塑性变形量的影响,得到最小塑性变形下的作业条件;选取输送速度和当量弹性系数三水平的5组参数组合进行分析研究,得到不同参数组合下的夹持输送过程中夹持力与时间的关系方程,以菠菜最小塑性变形量为目标,实现低损伤收获。为了验证用菠菜流变特性分析工作参数对菠菜损伤影响的可行性,进行了夹持输送试验,试验结果表明:当输送速度为25 mm/s、当量弹性系数为2 N/mm时,输送成功率为93. 3%,菠菜损伤率为6. 7%,夹持输送效果较好。