中国半个世纪以来夏季降水量变化总趋势

全球气候变化已经影响到人类生存环境的方方面面.全球升温及其幅度的区域差异,必然引起降水在区域分布的变化.文章利用160站点的夏季降水资料,分别计算出各个站点1951-2002年的变化斜率,以展示我国各地在这半个世纪中的降水总趋势变化的区域差异.通过分析发现,降水量总的变化趋势存在着随纬度而变化的规律:31°N以北区域近半个世纪降水量总的变化趋势是减少,31°N以南地区降水量以增加为主.40°N以北地区的降水变化幅度相对要小得多.区域上,中国西北和东南存在一个降水增多的趋势.中国降水的区域变化,在季风区受季风强弱变化影响;在非季风区,受西风强弱变化影响.     

中国降水量区域变化稳定性研究

利用中国气象中心160站点的实际观察资料,对中国半个世纪的降水变化进行了系统分析,发现中国的夏季降水变化稳定性有显著的纬度与海拔效应:纬度越高,方差值越小,降水变化的幅度也越小,稳定性越大;从海拔来看,海拔越高,降水稳定性越好,降水量的变化稳定性与海拔是成反相关关系.除过受区域水汽来源稳定性的影响,主要受全球降水稳定性的分布规律所制约;在海拔上,降水量稳定性的分布,除过受水汽来源影响外,还与水汽凝结的高度效应有一定的关系.     

地形对中国气温季节分布格局的差异影响

利用中国气象中心160台站的长期观测资料,分析发现中圜气温的空间分布格局的存在着巨大的季节差异:在冬季,等温线基本上与纬线平行;在夏季,等温线形成一个个闭合高温或低温中心.同时,这些高温中心都足以负地形地区为中心分布,而低温分布是以正地形地区为中心.可见,我国冬夏季节的气温分布格局是由不同的控制机制决定的:冬季气温分布格局主要由纬度控制,夏季气温分布格局主要南地形控制.     

全球变暖对中国区域相对湿度变化的影响

运用中国气象中心提供的中国标准气象站点实测的50年相对湿度月平均数据,采用等值线分析方法,研究了过去50年中国大气相对湿度的动态变化。分析表明：中国相对湿度区域变化,在秦岭淮河一线以北变化范围明显,主要以相对湿度减小为主;秦淮以南相对湿度变化在区域上表现不明显;从季节分析看,夏季变化幅度不大,其它三个季节变化幅度大,特别是冬季变化幅度最大;从区域看,以青藏高原、东北和华北变化显著。     

北京城市局地空气温度时空变化特征分析

目前中国正处于城镇化快速发展阶段,城市、气候和环境间的矛盾日益凸显。适宜的城市规划和景观设计可以有效地缓解热岛效应等城市气候问题对人居环境带来的负面影响。揭示城市户外热环境的时空变化格局及其影响因子,是调节和改善城市气候环境的理论基础。选取北京奥林匹克公园及其周边城市区域作为研究对象,采用移动路线观测法于2012年冬季和2013年夏季对研究区域内空气温度进行了测量,在此基础上对其局地空气温度的时空变化特征及其影响因子进行了分析。结果表明:即使在小尺度的城市区域内仍存在着明显的气温差异,研究区域内不同时相的温差大小为1.2~7.0℃,绿化状况以及测点周围环境特征对测点气温有着重要的影响。同时,研究也发现,研究区域内温差大小及其空间分布特征随着季节和昼夜的变化而变化。在夜晚,研究区域内的温差较大,气温分布也较为简单而明晰,此时公园范围内的空气温度明显低于周边建筑环境的空气温度,且随着与公园距离的增加,气温越高,呈现出明显的"公园冷岛"效应。然而在白天时,研究区域的空气温度差异较小,且空气温度的分布也较为复杂。研究区域内局地热岛强度总体呈现出冬季夜晚(5.9℃)夏季夜晚(3.4℃)夏季白天(1.8℃)冬季白天(1.7℃)的趋势,热岛强度晚上大于白天,而冬季晚上大于夏季晚上,即城市局地热岛强度的昼夜变化大于季节变化。     

空心莲子草入侵群落的昆虫丰富度和分布状况及其影响因素

昆虫组成及分布与环境密切相关,探究入侵植物群落中的昆虫丰富度及昆虫物种沿异质性环境梯度的分布规律,可为阐明入侵生态系统的物种共存机制和入侵植物防治提供依据。通过在中国南方5省(21°N—31°N)空心莲子草入侵的区域各设置25个水、陆样地,采用回归分析和典范对应分析(CCA)探讨了群落中昆虫丰富度及其分布与入侵植物群落特征(种群形态、α-物种多样性指数)和生境因子(经度、纬度、海拔、气温、降雨量、氨态氮和硝态氮)的关系。结果显示,(1)50个样地共记录昆虫25种,隶属于9目25科25属,鞘翅目和双翅目昆虫的物种丰富度较高,种群密度较大的昆虫依次为莲草直胸跳甲、东亚飞蝗和淡胸藜龟甲。(2)回归分析表明,水生昆虫丰富度随纬度、年均气温和海拔增加均呈明显的"先上升—后下降"单峰趋势;陆生昆虫丰富度随土壤硝态氮增加呈显著的线性上升趋势、随Pielou均匀度指数增加呈显著的线性下降趋势、随Patrick丰富度指数增加呈明显的"上升—下降—上升"波动趋势。(3)CCA表明,陆生昆虫分布的主导性环境因子为年均降雨量、经度和氨态氮,而水生昆虫分布的主导性环境因子为纬度和年均气温。(4)CCA排序图中,陆生样地的昆虫趋向分布于中等植物多样性水平区域,而水生样地的昆虫趋向分布于中等空心莲子草株高区域。该研究表明,异质性生境中空心莲子草入侵群落的昆虫分布及其驱动力存在明显差异,全球环境变化下应更加重视对该入侵生态系统的监测及生防昆虫资源筛选。     

贵州高原NDVI变化及其对气候变化的响应

中国南方喀斯特地区气候变化加剧,植被对气候变化响应反映十分敏感,动态监测植被变化对区域生态环境保护有重要意义。基于1999—2017年贵州高原遥感数据和气象数据,从年、季、月等不同时间尺度研究了NDVI动态变化及其对降水量、平均地表气温、最高地表气温、最低地表气温、平均气温、最高气温、最低气温、大型蒸发量、平均风速、平均相对湿度、日照时数等气候因子的响应特征。研究表明:近19 a,贵州NDVI以0.007 3 a~(-1)的速率呈显著上升趋势,其中,2011—2017年的上升幅度大于1999—2010年的上升幅度,NDVI变化与最低地表气温、最低气温呈显著正相关;春季、夏季、秋季、冬季NDVI均呈显著上升趋势,春季年增长率最大(0.009 3 a~(-1)),其次依次为秋季(0.007 0 a~(-1))、夏季(0.006 9 a~(-1))、冬季(0.004 6 a~(-1));春、秋季NDVI与最低地表气温呈显著正相关,最低气温影响较大,夏季、秋季NDVI受气温和降水共同影响,冬季NDVI受日照时数影响较大,四季NDVI受气温影响程度大于降水;1—12月NDVI均呈上升趋势,其中,4、5、8、10月呈极显著上升趋势,2、3、7、9、11、12月呈显著上升趋势;2、3月份和11、12月份NDVI在增长,表明生长季有所延长。NDVI与当月气象因子相关程度大于其与前一个月、前两个月的相关程度;气温的当月效应和滞后效应大于日照时数和水分条件的效应。温度对贵州NDVI的影响程度大于水分的影响,气温升高促进生长季延长是贵州高原的重要气候效应。     

苏南丘陵地区森林土壤酶活性季节变化

研究了苏南丘陵区不同林分土壤养分、酶活性的剖面分布以及酶活性的季节动态变化特征。研究结果表明,研究区土壤偏酸性,土壤中TN质量分数较高,有机质、TK、AK质量分数中等,TP、AP质量分数较低,土壤TN、有机质、AK、AP的质量分数及蔗糖酶、脲酶、H2O2酶、磷酸酶活性随着土壤深度的增加而逐渐降低。土壤酶活性在不同季节也存在差异,蔗糖酶活性的季节变化表现为：秋季〉夏季〉春季〉冬季,脲酶活性为：夏季〉春季〉秋季〉冬季,毛竹林土壤的磷酸酶活性为：秋季〉春季〉夏季〉冬季,其它3种林分土壤的磷酸酶活性为：秋季〉夏季〉春季〉冬季,H2O2酶活性在马尾松、麻栎、毛竹林土壤内表现为：春季〉秋季〉夏季〉冬季,在杉木内林土壤内表现为：春季〉夏季〉秋季〉冬季。在α=0.01或α=0.05水平下,土壤酶活性与土壤TN、AP、AK、有机质及重元素Pb、Cu、Zn、Cr、Ni呈显著或极显著相关,与土壤容重呈显著或极显著负相关,冬季蔗糖酶与其它3个季节的蔗糖酶呈现极显著或显著正相关;秋季磷酸酶与其它3个季节的磷酸酶呈现极显著或显著正相关;夏季脲酶与其它3个季节的脲酶呈现极显著正相关;夏季H2O2酶与其它3个季节的H2O2酶呈现极显著正相关。     

近年来长江流域气溶胶光学厚度时空变化特征分析

利用2000年3月至2011年2月MODIS Level3遥感反演大气气溶胶光学厚度（AOD）产品数据,结合中国地形的3大阶梯分布,分析近年来长江流域气溶胶光学厚度的时空变化特征。结果表明,近12年来,长江流域的年平均AOD值在0．38,～,0．44之间变化,其中“第一阶梯”年平均AOD呈极显著下降趋势（P〈0．01）,“第二阶梯”和“第三阶梯”则呈上升趋势,但趋势不显著（P〉0．05）;4季平均AOD除春季呈下降趋势,其他3季均为上升趋势,其中冬季上升速率最快,线性倾向率为0．004·a-1（P〈0．05）,春季AOD与其他季节的差距在逐步减小;长江流域3大阶梯AOD具有鲜明的季节变化特征,基本上是春夏季较大,秋冬季较小,具体表现为春季最大,从夏季到冬季逐渐减小,冬季到来年春季跳跃性增高,但由于地理位置、地形、气候、人类活动等因素的影响,不同区域又有所差异;AOD年平均值和四季平均值均表现为“第三阶梯”〉“第二阶梯”〉“第一阶梯”。长江流域年平均AOD变化空间差异显著,其中显著减少区域占整个流域面积的17．54％,主要分布在“第一阶梯”;显著增加的区域仅占流域总面积的5．23％,主要分布在“第二阶梯”和“第三阶梯”。另外,由于海拔、地形及山脉阻挡等诸多因素影响,导致在地形阶梯间高程突变线左右两边的狭窄区域,AOD分布存在低处明显大于高处的现象。这些结果有助于长江流域的区域气候变化和环境研究。     

西安市混合功能区冬夏季大气颗粒物中可溶性Fe的分布特征

可溶性铁(Fe)一方面作为营养元素影响着生物地球化学循环,另一方面作为氧化剂对大气二次气溶胶的形成也有重要影响.本文分别开展了西安市混合功能区冬夏季不同粒径大气颗粒物的观测研究,通过使用改良的液体波导毛细管池(LWCC)测定颗粒物中酸性介质提取的可溶性铁浓度,并探究其季节变化、昼夜分布及粒径分布特征.季节分布特征表明,可溶性Fe(Ⅱ)浓度冬季高于夏季,而可溶性Fe(Ⅲ)浓度则夏季高于冬季.不同价态的可溶性Fe的季节分布特征差异明显,白天PM2.5中可溶性Fe(Ⅱ)和总可溶性性Fe的质量浓度和溶解度都大于夜晚的PM2.5样品,Fe(Ⅲ)则白天与夜晚无明显区别.粒径分布结果表明,溶解性Fe主要分布在细颗粒物中,且大气颗粒物的粒径越小,Fe(Ⅱ)sol与Fe(Ⅱ)total之比的变化范围越大,可溶性Fe(Ⅱ)和Fe(Ⅲ)之间的转化更为活跃.     

Achieving Open Access to Conservation Science

Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación     

Some polyphagous Homoptera gain protection from their natural enemies by feeding on the toxic plantsSpartium junceum andErythrina corallodendrum (Leguminosae)

Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

Sequestration of cucurbitacin analogs by New and Old World chrysomelid leaf beetles in the tribe Luperini

Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.     

Effects of Controlled Fire and Livestock Grazing on Bird Communities in East African Savannas

Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

What Every Conservation Biologist Should Know about Economic Theory

Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.