深圳市显著排放VOCs的园林植物调查与分析

对深圳地区的主要园林树种、地带性植被的代表种共计158种植物释放的生物源的挥发性有机物（biogenic volatileorganic compounds,BVOCs）采用流动式、封闭式采样法采样,运至美国进行GC-MS分析测量.结果表明,短穗鱼尾葵（Caryotamitis）、海红豆（Adenanthera pavonina var.microsperma）、杧果（Mangifera indica）、海漆（Excoecoria agalloch）等31种植物具有释放异戊二烯的能力;另有鸡蛋果（Passiflora edulis）、小琴丝竹（Bambusa glaucescens cv.silverstripe）、山苍子（Litsea cubeba）、大型双子铁（Dioon spinulosum）等52种植物具有释放单萜烯类化合物的能力.对红树植物的测量表明,该类植物普遍具有释放单萜烯的能力.上述结果为建立深圳及周边地区的环境质量模型提供了重要数据,同时也可为我国热带亚热带城市大面积绿化以及经济林、生态林和防护林等的树种选择提供参考.     

UV-B辐射对亚热带森林凋落叶氮、磷元素释放的影响

UV-B辐射对凋落物分解过程的影响已成为全球变化生态学研究中的前沿和热点问题之一.采用分解袋法对自然和UV-B辐射滤减两种环境下亚热带6种代表性树种(杉木、马尾松、木荷、香樟、青冈和甜槠)凋落叶氮、磷元素的释放动态进行了研究.结果表明,凋落叶氮元素的动态表现为直接富集、释放-富集和释放-富集-释放3种模式,磷元素的动态表现为直接释放、富集-释放-富集和无明显变化3种模式.与对照相比,UV-B辐射滤减显著延缓了甜槠凋落叶氮元素及青冈和甜槠凋落叶磷元素的释放(P<0.05),但促进了香樟凋落叶磷元素的释放(P<0.05),对其他树种凋落叶的氮或磷释放无显著影响.凋落叶的初始氮含量和C/N比值不能解释氮释放动态,C/P比值可以部分解释磷的释放.全球环境变化背景下UV-B辐射在湿润亚热带地区森林生态系统过程中的作用尚需进一步认识和理解.     

刈割对华北平原人工草地土壤呼吸速率的影响

根据中国科学院禹城综合试验站牧草生态试验场土壤呼吸测定数据,分析了刈割前后3年生和6年生苜蓿、白三叶及小黑麦4种人工草地土壤呼吸日变化特征及刈割对草地土壤呼吸速率的影响。结果表明:①刈割前不同牧草地的土壤呼吸强度差异明显,依次为3年生苜蓿>6年生苜蓿>白三叶>小黑麦,刈割后不同牧草地的土壤呼吸强度相差不大,土壤呼吸速率在3.0~3.5 μmol CO₂·m^-2·s^-1之间;②刈割前不同牧草地的土壤呼吸日变化不相同,6年生苜蓿与小黑麦草地刈割前土壤呼吸速率由9:00开始逐渐增强,在12:00~16:00之间持续较高,以后逐渐下降,3年生苜蓿与白三叶草草地土壤呼吸速率在9:00~12:00之间逐渐升高,12:00到达峰值,之后逐渐下降;③与刈割前相比,4个处理牧草刈割10 d后其草地的土壤呼吸速率下降了30%~40%;④刈割前后Q₁₀值在1~2.32之间,平均值为1.37,刈割前平均值为1.63,刈割后平均值降为1.10。     

Ecological pressures on grassland ecosystems and their conservation strategies in Northern China

In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economic development,resources exploitation,and global climate change,with human-related activities being overriding factors.Overgrazing was an important reason for grassland imbalance,causing soil erosion and desertification,especially during the sensitive spring greening phase.In steppe zones,commercial coal mining was destructive to the ecological environment.Regarding long-term strategies,we recommend that policy-makers devote more consideration to a new conceptual approach for transforming grasslands through shifting the focus from die grassland’s traditional production functions to meir ecological functions.Applying this concept,adaptive countermeasures should be developed to reduce human impacts based on the environmental capacities of grasslands.Moreover,we recommend the development of environment-friendly industries and reduction of pressures from human activities as effective measures for maintaining the balance between sustainable economic development and grassland conservation.Lastly,we suggest that restoration of degraded grasslands should conform to the principle of natural vegetation to further improve the ecological adaptability of plants and ecosystem stability.This study is expected to provide scientific support for policy-makers engaged in grassland protection.     

锡林郭勒草原保护区实现保护与发展双赢对策研究

内蒙古锡林郭勒草原保护区是我国唯一列入世界生物圈保护区网络的草原保护区，从草地资源利用、保护区管理和经济社会不同角度分析了保护区草原大面积退化的成因。以退化草原恢复为目标，对锡林郭勒草原保护区进行了新的规划．核心区面积占保护区总面积的比例由原来的0．17％增加到新规划的6．85％。以保护区内面积最大的白音锡勒牧场为研究区．利用2004年8月TM数字化磁带数据，在估算出白音锡勒牧场草原地上生物量的基础上，划分出未退化、轻度退化、中度退化、重度退化4个等级，针对不同退化等级草场制定出不同的牧草产量利用率。并计算出以退化草原恢复为目标的草原合理放牧强度、相应面积和载畜量，结果为研究区平均合理放牧强度为43只标准羊单位／km^2。白音锡勒牧场2003年平均放牧强度为86只标准羊单位／km^2。最后提出应改变锡林郭勒草原单一的畜牧业经济机构，“以工养草”；大力扶植牧民从事生态旅游和针对不同退化等级草原制定合理的载畜量等实现保护区环境保护与经济发展双赢的对策。     

毛乌素沙地土地利用/覆被变化对草地土壤物理、化学和矿物学性质的影响

In arid and semiarid regions, cultivation and shrub invasion are two important factors to impact grassland. However, there are few studies to compare the effects of cultivation and shrub invasion on soil physical, chemical and mineralogical properties. In this study, three sampling sites, which respectively represent the native grassland, cultivated grassland (farmland), and shrub invasion of grassland (shrub land) in Mu Us sand land, were selected and soil samples were collected and measured for soil particle size distribution (PSD), soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) concentrations, and relative percentages of mineralogical components. Results showed that cultivation and shrub invasion significantly altered the soil PSD, soil C, N and P concentrations and pools, and the relative percentages of soil mineralogical components of the grassland ecosystems. Grassland cultivation and shrub invasion significantly decreased the contents of silt and clay. Moreover, the land cover change from grassland to farmland or shrubland significantly resulted in soil organic carbon, total nitrogen and soil carbonate loss. In this study, we found that grassland cultivation resulted in more sand accumulation and more soil C and N losses than shrub invasion, which indicated that grassland cultivation was stronger than shrub invasion to accelerate soil desertification in Mu Us sand land.     

内蒙古草原煤矿区周边土壤汞分布特征

为探究汞(Hg)对内蒙古地区草原土壤的影响,于2015年5月～2016年5月对呼伦贝尔(HB)、鄂尔多斯(ER)、霍林郭勒(HL)和锡林浩特(XL)电厂周边土壤Hg分布进行研究。设计采样路线,分别位于四个地区的东、西、南、北,每条路线上每隔5km布点,对土壤样品进行采集,并用原子荧光光度计(普析通用PF-7原子荧光光度计)对土壤中Hg含量进行测定。实验结果表明:四个地区土壤Hg含量的平均值均高于Hg在土壤中的背景值,受人为活动干扰明显;空间积累特征为:土壤中Hg的超背景值倍率由污染源的中心向四周逐渐递减,但各方向上的递减速率差异很大,各方向上的传输距离也有一定差异,其空间分布表现出明显的方向性;利用单因子指数法(P)和潜在生态危害指数法(Ei)对四个地区汞的污染程度及风险评价进行分析发现,PHB处于无污染状态,PER属于轻度污染,PHL和PXL属于中度污染; HB和ER地区分别属于强生态风险程度(Ⅲ级)、很强生态风险程度(Ⅳ级)、HL和XL地区属于极强生态风险程度(Ⅴ级)。     

Multi-scales Analysis of Driving Forces on Land Use/Cover Change in China: Taking Farmland Returning to Forest or Grassland as a Case

Abstract

Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country)—regional (province)—local (county)—household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers' income and improving agricultural production conditions as the main types; at the household scale, the national policy meeting farmers' demands and the optimization of individual interests are all driving forces.     

氮沉降对草原凋落物分解的影响

大气氮沉降增加是全球变化的重要现象之一,草原生态系统对氮沉降增加的响应成为草地生态学的研究热点之一。凋落物分解是草原生态系统养分循环和能量流动的主要途径,氮沉降增加引起草原植物群落结构变化,导致凋落物质量、土壤肥力、土壤微生物和土壤动物的变化,最终影响凋落物的分解。本文综述了氮沉降对草原凋落物结构、化学组成和分解环境的影响等方面的国内外最新研究进展,讨论了需进一步加强研究的内容,以期为进一步拓展该领域研究的广度和深度、为全面分析和评估全球变化对草原生态系统的影响提供参考。     

油田开发区域草原生态环境演变规律及保护恢复对策

针对目前大庆地区草原面积逐渐减少;草原“三化”加剧,草质变劣;草原土壤板结,污染严重以及草原支离破碎的现状,分析了油田开发建设对生态的影响,并从宏观上提出了对油田区草原植被的保护对策与恢复措施。