未来气候情景下中国亚热带地区柑桔气候风险度变化

选取中国亚热带地区273个气象站点1961-2005年逐日气象资料,结合IPCC SRES A2情景下未来亚热带地区温度、降水模拟数据,综合考虑柑桔气候适宜性水平及其变率变化,构建柑桔的风险度模型,对未来中国亚热带地区柑桔气候风险性变化进行了研究。结果表明,中国亚热带地区柑桔风险度出现了不同速度和形式的趋势性变化,近46 a来,柑桔气候风险度有逐渐增加的趋势,尤其以20世纪80年代初以来增加最快;同时中国亚热带地区柑桔生产的气候风险性对全球气候变化的响应也存在着区域分异性,中国亚热带柑桔气候风险在其北部边缘地带和西部高山地区风险度是降低的,在中部和南部风险度是升高的,尤其以中部地带升高最快。     

太白山植被指数时空变化及其对区域温度的响应

太白山地处陕西秦岭腹地中段,是秦岭最高峰。基于5月的遥感影像提取研究区NDVI数据,结合实际调查,对太白山自然保护区1979-2009年植被指数变化特征进行分析,研究不同植被带NDVI对温度变化的响应。结果表明:近30 a来,太白山5月植被指数NDVI平均值达0.2以上的面积占研究区面积的89.5%,植被整体覆盖较高;但NDVI表现出明显的垂直性差异,中低海拔区NDVI大多分布在0.2以上,而较高海拔区NDVI则主要分布在0.2~0.5区间。有56%以上的区域NDVI基本没有发生变化;NDVI增加极显著和减少极显著区占总面积的4.88%和3.92%。近30 a来,研究区年平均温度呈明显上升趋势,线性增加趋势为0.35 ℃/10 a;随着海拔的升高,各植被带NDVI对温度的变化更为敏感,高海拔植被对温度变化的敏感性远大于低海拔植被,即人为影响相对较小、但海拔相差巨大的太白山植被生态系统,已成为气候变化影响的敏感场所。     

基于景观指数的细碎化对耕地利用效率影响研究——以扬州市里下河区域为例

从中观尺度研究细碎化对耕地利用效率影响,探寻遏制细碎化水平降低因素,以为高效农地利用政策制定提供依据。选取景观指数量化耕地细碎化水平,用数据包络分析(DEA)法对耕地利用效率进行评价,最后采用计量经济模型检验细碎化对耕地利用效率影响。结果表明:研究区扬州市里下河区域30个乡镇的耕地利用综合效率、纯技术效率与规模效率的平均值分别是0.949 3、0.972 2和0.977 0,具有一定提升空间;表征细碎化的第一主成分与地块平均面积、地块密度、面积加权形状指数和面积加权分维数的载荷值大于88%,第二主成分与边界密度指数载荷值大于91%;第一主成分对纯技术效率与规模效率的影响弹性是-0.002 7和-0.085 6,第二主成分对纯技术效率与规模效率的影响弹性是-0.001 1和-0.002 4。细碎化对耕地利用规模效率与纯技术效率产生显著负影响,且对规模效率影响大于对纯技术效率影响;应从地块面积、分布与形状等方面来降低细碎化程度以提高耕地生产能力。     

黄土高原典型土壤剖面有机碳物理组分分布特征

为阐明黄土高原典型区域土壤轻组有机碳(LFOC)和重组有机碳(HFOC)含量随土壤类型、土层和土地利用方式的变化规律,分析了从北向南依次分布的干润砂质新成土(神木)、黄土正常新成土(延安)和土垫旱耕人为土(杨凌)等典型土壤剖面(0~200 cm)LFOC和HFOC含量及分布特征。结果表明,从南到北,土壤LFOC和HFOC含量均显著下降 (P<0.05),整体来看,黄土高原典型区域土壤LFOC含量占有机碳比例偏低;LFOC含量及在土壤有机碳中的分配比例随土层加深而递减,其比例变化范围为1%~26%;土地利用方式对浅层土壤LFOC和HFOC含量影响较为显著,草地土壤0~60 cm土层LFOC和HFOC含量均高于同层次农田土壤(P<0.05),60 cm土层以下差异不显著;土壤LFOC和HFOC含量与微生物量碳、微生物量氮含量均呈极显著正相关关系(P<0.01),前者的相关性系数更高,分别为0.841和0.507,表明土壤LFOC与微生物关系非常密切,是土壤微生物重要的碳和能量来源,极易受土地利用方式和微生物活性影响,同时表明用LFOC的变化更能快速有效地说明土壤碳库的变化规律。     

忻州市土地利用现状的环境敏感区分析

随着新一轮土地利用规划修编展开,针对忻州市土地利用存在的环境问题,利用调查资料和相关研究成果,有效管理土地利用空间向环境敏感地区伸展,减缓环境敏感地区的环境压力和生态胁迫,为市域土地利用方式和分区方案制定提供环境敏感性依据.从规划方案与面临的土地生态问题入手,划分生态环境、水源保护、污染影响、优质农田以及煤矿塌陷五类环境敏感区,并进行忻州市环境敏感地综合评价,明确其空间分布范围.研究结果表明,极高敏感、高敏感区占全市总面积的4%,较高敏感区和一般敏感区分别占10.5%和7.5%,低敏感区和非敏感区分别占40%和38%.通过分析规划土地利用功能分区方案与环境的协调性, 在土地利用规划过程中,提出土地利用方式和空间布局优化对策.     

Effects of temperature variation on TSD in turtle (C. picta) populations

We formulate a two-sex model of temperature-dependent sex determination (TSD) for a freshwater turtle (C. picta) population. The aim is to understand how environmental temperature variations and nest heat conduction properties affect the long term dynamics of the population. This is a key to understanding how global temperature changes may affect their survival. With stochastic inputs of ambient temperature and solar radiation, the model uses the heat equation to determine the temperature in the egg layer in the nest; in turn, this determines the sex ratio in the egg clutch using a variable degree-day model. Finally, a nonlinear Leslie type, stage-based, two-sex model, is used to determine the long term male and female populations. A two-sex model is required because of different development rates for males and females. The model is flexible enough to enable other researchers to examine the effects of temperature variation variations on other species with TSD, e.g., crocodilians, reptilians, as well as other turtle species. It can be adapted to study effects of nest location, soil type, rain events, different incubation periods, and density effects, for example, the dependence of the mating function on the ratio of males to females and each’s contribution to the sex of hatchlings. Modifications can be easily made to fit a specific life history traits. The model is a beginning step in understanding the long term, high fitness shown by many reptile species with TSD, and it may suggest to experimentalists what data may be relevant to these issues; it can also be useful to wildlife managers in developing strategies for intervention if needed. Among the principal findings are that temperature variability and detailed nest heat conduction properties may buffer projected negative effects on a population.     

Matching the Multiple Scales of Conservation with the Multiple Scales of Climate Change

Abstract:  To anticipate the rapidly changing world resulting from global climate change, the projections of climate models must be incorporated into conservation. This requires that the scales of conservation be aligned with the scales of climate-change projections. We considered how conservation has incorporated spatial scale into protecting biodiversity, how the projections of climate-change models vary with scale, and how the two do or do not align. Conservation planners use information about past and current ecological conditions at multiple scales to identify conservation targets and threats and guide conservation actions. Projections of climate change are also made at multiple scales, from global and regional circulation models to projections downscaled to local scales. These downscaled projections carry with them the uncertainties associated with the broad-scale models from which they are derived; thus, their high resolution may be more apparent than real. Conservation at regional or global scales is about establishing priorities and influencing policy. At these scales, the coarseness and uncertainties of global and regional climate models may be less important than what they reveal about possible futures. At the ecoregional scale, the uncertainties associated with downscaling climate models become more critical because the distributions of conservation targets on which plans are founded may shift under future climates. At a local scale, variations in topography and land cover influence local climate, often overriding the projections of broad-scale climate models and increasing uncertainty. Despite the uncertainties, ecologists and conservationists must work with climate-change modelers to focus on the most likely projections. The future will be different from the past and full of surprises; judicious use of model projections at appropriate scales may help us prepare.     

Designing Climate-Smart Conservation: Guidance and Case Studies

Abstract:  To be successful, conservation practitioners and resource managers must fully integrate the effects of climate change into all planning projects. Some conservation practitioners are beginning to develop, test, and implement new approaches that are designed to deal with climate change. We devised four basic tenets that are essential in climate-change adaptation for conservation: protect adequate and appropriate space, reduce nonclimate stresses, use adaptive management to implement and test climate-change adaptation strategies, and work to reduce the rate and extent of climate change to reduce overall risk. To illustrate how this approach applies in the real world, we explored case studies of coral reefs in the Florida Keys; mangrove forests in Fiji, Tanzania, and Cameroon; sea-level rise and sea turtles in the Caribbean; tigers in the Sundarbans of India; and national planning in Madagascar. Through implementation of these tenets conservation efforts in each of these regions can be made more robust in the face of climate change. Although these approaches require reconsidering some traditional approaches to conservation, this new paradigm is technologically, economically, and intellectually feasible.     

冬季土地管理对稻季CH4产生、氧化和排放的影响

通过室内培养和田间试验测定了冬季休闲、种麦和淹水处理水稻生长期CH4的产生潜力、氧化潜力及其排放通量,以探讨冬季土地管理对后续稻季CH4产生、氧化和排放的影响。结果表明：休闲与种麦处理间CH4产生潜力无显著差异（P〉0．05）,但2者均显著低于淹水处理（P〈0．05）;各处理间CH4氧化潜力无显著差异（P〉0．05）,土壤中NH4^＋-N含量可能是较冬季土地管理更为重要的影响CH4氧化潜力的因素;休闲处理CH4平均排放通量显著高于种麦处理（P〈0．05）,但2者均显著低于淹水处理（P〈0．05）。冬季持续淹水稻田CH4产生潜力显著高于冬季排水稻田是其CH4排放量远高于冬季排水稻田的原因。冬季土地管理对稻季CH4排放的影响主要受CH4产生潜力而非CH4氧化潜力的限制。     

热带增宽及其对中国东部亚热带森林植被的影响

全球气候变暖已是不争的事实,现今气候变暖的趋势已由每百年（1901--2000）增加0．6℃的记录升高为0．74℃（1906—2005）。其中高纬度地区增温特别显著,成为世界关注的热点。与之对比,热带地区的气候变化以及热带森林对它的反应报道甚少。事实上,自1970s中期以来,热带温度是每lO年升高0．26oC;同时气候模型预测到本世纪末热带地区温度将上升2．1-4．5℃。这些预测是有根据的,但究竟不是直接的证据。因此,本文综合了许多专家对热带地球物理学和大气层特性的多年观测、分析和研究的成果,其结论认为：至少自1979年以来许多热带大气层固有的特征发生变化并向地球极地推进和位移,这些根据是：（1）热带高空的哈德利环流增强并向极地扩展;（21位于热带边缘的亚热带射流向极地移动;（3）热带亚热带对流层顶高度和位置的变化;（4）热带高空平流层臭氧柱总量浓度的变化。据上述特征的变化证明数十年来热带向极地增宽纬度2°～5°（～8°）,一般确认为2．5°。由于热带增宽的驱动,广东50年的气温记录表明气候持续变暖,按增暖趋势推算,预估到2020年,现在的雷州半岛南部可能变成中热带;广东东南沿海将由目前的南亚热带变为北热带（占全省面积约1／3）;其余大部分地区为南亚热带;中亚热带基本上将退出广东（仅剩下东北角一偶）。此预测意味着南岭地区将成为南亚热带的边缘地。