Stable isotope evidence for nutritional stress,competition, and loss of functional habitat as factors limiting recovery of rare antelope in southern Africa

A major focus in population ecology is understanding factors that limit rare species. We used stable isotope approaches to diet to determine whether remaining rare antelope populations in Kruger National Park (KNP), South Africa experience i) nutritional stress; ii) competition with sympatric bulk grazers; iii) reduced habitat heterogeneity. Rare species consumed near-pure C₄ grass-based diets throughout the seasonal cycle, in contrast to field observations that reported significant levels of C₃ consumption (browse) by these taxa. This finding, coupled with low faecal %N at the height of the dry season, may indicate nutritional stress, but recent isotopic studies of the same species elsewhere in Africa suggest that field observations overestimated levels of browse consumption. We find little evidence for diet niche overlap between rare antelope with bulk grazing species. This partitioning of resources (interpreted mainly as tall- versus short-grass grazing, respectively), is consistent with reported differences in observed diet, and comparative oral morphology. Last, we find less seasonal diet variations amongst bulk grazers feeding in rare antelope habitats compared with other landscapes. We propose that loss of functional heterogeneity, apparently brought about by high densities of artificial waterholes, limits recovery of diet- and habitat-selective rare antelope populations in KNP.     

北京市郊区居民汽车拥有和使用状况与活动空间的关系

机动化与郊区化对城市空间结构与社会生活产生了深远的影响,私人汽车已日渐成为中国城市居民日常出行的重要交通工具。汽车所有权与汽车出行快速上升及其所带来的日常行为变化已经成为中西方学者共同关注的话题。西方学者对机动化与居民活动空间的关系进行了深入的探讨,但是国内这一方面的研究刚刚起步。基于GPS与活动日志相结合的居民一周活动与出行数据,采用GIS空间分析,从非汇总角度对郊区居民的整日活动空间进行测度,分析汽车拥有量与汽车使用对居民整日活动空间的影响。结果表明：机动化对居民活动空间产生深刻影响,家庭汽车所有状况与家庭汽车分配影响个体日常活动空间的分布,活动空间与是否使用小汽车出行具有显著的相关关系。     

Effects of habitat degradation on the lizard assemblage in the Arid Chaco,central Argentina

Habitat degradation in the Chaco has been intense and widespread since European settlement. Detailed knowledge about its effects on the Chaco fauna is scarce despite the critical importance of such information for biodiversity conservation. The effects of habitat degradation on the Arid Chaco lizard assemblage were evaluated by comparing species richness and abundance in four sites along a gradient of increasing vegetation degradation. Two undisturbed sites (primary forest and grassland), and two sites with different degrees of forest degradation (moderate and severe) were selected. Ten lizard species were recorded (nine were trapped and one was sighted), totaling 1122 captures. Abundance of Homonota fasciata, Leiosaurus paronae, Liolaemus chacoensis and Stenocercus doellojuradoi was highest in the primary forest, with significantly lower values in the remaining three sites. Teius teyou and Tropidurus etheridgei were more abundant in the moderately and severely degraded forests than in the primary forest. Management implications of our results in terms of lizard biodiversity in the Chaco are analyzed.     

蒙古野驴(Equus hemionus)昼间行为时间分配初探

于2007 年和2010 年采用焦点动物取样法研究了新疆卡拉麦里山有蹄类野生动物保护区蒙古野驴昼间行为时间分配和活动节律,共采集行为数据460 h,观察蒙古野驴2 760 头次,将蒙古野驴昼间行为分为采食、移动、警戒、休息和“其他”5 类。采用卡方检验分析不同季节各种行为时间分配,结果表明：季节因素对蒙古野驴行为时间分配存在极显著影响（χ2=79.06,df=12,P<0.01）。采用ANOVA分析同季节不同行为间差异,结果表明,春季：移动、警戒、“其他”两两间无显著差异（[WTBX]P＞0.05）,其余两两间差异显著（P＜0.05）;夏季：仅移动与“其他”间无显著差异（P＞0.05）;秋冬季：仅警戒与“其他”间无显著差异（P＞0.05）。对蒙古野驴昼间活动节律研究结果表明,蒙古野驴采食时间比例在春季各时段均较高（＞45%）,仅中午（14:00～15:00）有1个低谷（27.62%）,夏秋季则为晨昏采食模式,冬季采食峰值（87.85%）在中午时段（13:00～14:00）。休息和采食高峰在各季节交叉出现,呈现此消彼长的趋势。各季节移动主要发生在晨昏时段。蒙古野驴以特定的行为时间分配模式和活动节律适应环境条件季节性变化,如气候条件、食物资源、人为干扰、生理期、昼间长度、捕食风险等。     

Tectonic and eustatic controls on Pliocene accommodation space along the front of the southern Apennine thrust‐belt (Basilicata,southern Italy)

The stratigraphical organization of the Pliocene thrust‐top deposits cropping out at the front of the Southern Apennine thrust‐belt has been debated for a long time taking a great importance in the context of the geodynamics of the Central Mediterranean area. During this time, spreading episodes in the Apennine backarc zone alternate with important phases of overthrusting in the thrust‐belt. As a consequence, the Pliocene succession appears to be arranged in a series of stacked units, recording the poliphase tectonic history that leads to the building of the front of the southern Apennine thrust‐belt. Although there is not yet an accordance on the nature and position of the main unconformities bounding the thrust‐top units, all authors agree that the creation of new accommodation space is mainly ruled by contractional tectonics consequent to the eastward nappe propagation according to the Apennine vergence polarity. A detailed geological survey, carried out along a large portion of southern Apennine thrust‐belt front, running south of the Vulture volcano, allowed the collecting of new data concerning the basinal‐formation mechanisms acting during the sedimentation of Pliocene deposits. From this analysis, it is clear that even if contractional tectonics is the predominant factor controlling the creation or destruction of accommodation space, other mechanisms, as well as wedge uplift‐related extensional tectonics and eustasy, could have also played a significant role in the basin accommodation. In order the considered sector of southern Apennines can provide an useful example about the complex phenomena occurring at mountain belt front where the accommodation space results from a concomitance of eustatic and tectonic factors mainly linked to the accretionary wedge activity.     

Precipitation impacts on mule deer habitat use in the chihuahuan desert of Mexico

In arid lands, food resources and predation risk become major decision factors in mule deer habitat use. We examined variables related to these two factors that might determine mule deer (Odocoileus hemionus) habitat use in a warm desert at two spatial scales: the macro-habitat scale, which relates to home range decisions, and the micro-habitat scale, which relates to decisions made during foraging. Our prediction was that habitat use should primarily be explained by food variables and, to a lesser degree, by variables related to predation risk by pumas (Puma concolor). We mapped all deer pellet groups in 72, 1 ha quadrats in the Mapimí Biosphere Reserve and measured food and habitat variables over two years with different precipitation amounts. The area was used more intensively during the dry year. Under drier conditions, deer habitat use was explained primarily by food resource variables and secondarily by variables related with predation risk. During the wetter year, food resources became unimportant while cover and visibility explained deer habitat use. The data suggest that the tradeoffs deer are willing to make between food resources and predation risk in an arid environment are strongly affected by food resource levels, as influenced by precipitation.     

Siliceous algae-based seasonal temperature inference and indicator pollen tracking ca. 4,000 years of climate/land use dependency in the southern Austrian Alps

Diatom and chrysophyte cyst-based reconstructions of the dates of spring and autumn lake-mixing enabled us to estimate spring (ST_anom) and autumn (AT_anom) temperature anomalies as well as ice-cover of the last ca. 4,000 years in a lake sediment core (Oberer Landschitzsee, 2,076 m a.s.l.) from the southern slopes of the Austrian Central Alps. The two independently inferred temperature anomalies were significantly correlated. On average, spring and autumn temperatures were lower during the two millennia B.C than during 0–1,300 A.D. Marked spring and autumn temperature minima occurred at about 1,300 and 600 B.C. At about 1,300 A.D, ST_anom declined again. Spring-temperature anomalies during Roman and Medieval times equaled or slightly exceeded the modern values and paralleled tree-line and glacier fluctuations. The de-coupling of autumn and spring climates, which began during the Medieval period, might indicate changes in major circulation modes. It was assumed that the North-Atlantic influence, triggering winter-rain climate in the Northern Mediterranean, became weaker during Medieval times, resulting in a trend towards warmer autumns and overall more continental climate conditions in the study area. Four pulses of land use, inferred from indicator pollen, occurred during (1) the Early to Late Bronze, (2) the transition from Late Bronze to Early Iron Age (Hallstatt), (3) Late Iron Age (La Tène, Celtic time) to Roman times, and (4) during high to late Medieval times. Climate seemed to be an important, though complex, trigger of Alpine land use.     

Effects of seasonal grazing,drought, fire,and carbon enrichment on soil microarthropods in a desert grassland

This study was designed to test hypotheses about the combined effects of short-term, seasonal grazing with seasonal drought, fire, and carbon enrichment on soil microarthropod communities in a Chihuahuan Desert grassland. The study was conducted in eighteen 0.5 ha plots following three consecutive years of treatment: six plots intensively grazed in summer, six in winter, and six not grazed. There was no difference in perennial grass cover on the summer-grazed and winter-grazed plots. Intensive seasonal grazing had no effect on the abundance and community composition of soil microarthropods. Within each plot there were six subplots: summer rain-out, winter rain-out, burned, glucose amendment, rain-out control and burn-glucose control. Fire and carbon enrichment had no significant effect on soil microarthropod abundance or community composition. The average number of microarthropods ranged from 8915 ± 1422 m⁻² in the ungrazed, unburned plots to 7175 ± 1232 m⁻² in the winter-grazed, unburned plots. Microarthropod densities in the glucose-amended plots were 8917 ± 4902 m⁻² in the winter-grazed plots and 10,731 ± 863 m⁻² in the glucose-amended, summer-grazed subplots.The prostigamatid mite, Tydeus sp., was the most abundant microarthropod taxon in all treatment plots.     

Effect of the Cretaceous Serra Geral igneous event on the temperatures and heat flow of the Parana Basin, southern Brazil

We investigate the effects of the cooling of intrusive and extrusive igneous bodies on the temperature history and surface heat flow of the Parana Basin. The Serra Geral igneous event (130–135 Ma) covered most of this basin with flood basalts. Associated with this event numerous sills and dykes intruded the sediments and basement, and extensive underplating may have occurred in the lower crust and upper mantle beneath the basin. We develop an analytical model of the conductive cooling of tabular intrusive bodies and use it to calculate temperatures within the sediments as a function of time since emplacement. Depending on the thickness of these igneous bodies and the timing of sequential emplacement, the thermal history of a given locus in the basin can range from a simple extended period of higher temperatures to multiple episodes of peak temperatures separated by cooling intervals. The cooling of surface flood basalts, sills and dykes is capable of maintaining temperatures abovc the normal geothermal gradient temperatures for a few hundred thousand years, while large-scale underplating may influence temperatures for up to 10 million years. We conclude that any residual heat from the cooling of the Serra Geral igneous rocks has long since decayed to insignificant values and that present-day temperatures and heat flow are not affected. However, the burial of the sediments beneath the thick basalt cap caused a permanent temperature increase of up to 50°C in the underlying sediments since the beginning of the Cretaceous.     

太行山淇河流域土地利用变化对生境的影响

山地作为陆地表面的特殊地域单元,地形起伏较大,生态系统较为脆弱,对全球变化信号有放大作用。因此,研究山地土地利用变化对生境质量的影响,对于权衡区域生态保护与发展及土地资源的可持续利用具有重要意义。本文基于InVEST模型,结合土地利用数据,并从地形起伏度视角,对太行山淇河流域2000-2015年生境质量进行研究。结果表明：①2000-2015年期间,淇河流域土地利用变化表现为耕地、林地面积逐渐减少,草地、建设用地面积逐渐增加。②流域整体生境质量较好,平均生境质量指数均超过0.7,且2015年有明显提升。③淇河流域的生境质量变化受地类变化影响较大。耕地、草地、建设用地由于受到过人为干扰的影响,其生境出现不同程度的退化;采伐、毁林开荒等行为导致林地的生境也开始缓慢退化,但由于林地的植被覆盖度较高,抗干扰能力较强,加上逐渐开始对其进行恢复,生境质量水平依然较高。④该流域生境质量在地形起伏度上的分布特征表现为平坦区和微起伏区以一般等级生境质量为主,小起伏区和中起伏区则以高度重要和极重要等级生境质量为主。     

Effect of the Cretaceous Serra Geral igneous event on the temperatures and heat flow of the Paraná Basin, southern Brazil

We investigate the effects of the cooling of intrusive and extrusive igneous bodies on the temperature history and surface heat flow of the Paraná Basin. The Serra Geral igneous event (130–135 Ma) covered most of this basin with flood basalts. Associated with this event numerous sills and dykes intruded the sediments and basement, and extensive underplating may have occurred in the lower crust and upper mantle beneath the basin. We develop an analytical model of the conductive cooling of tabular intrusive bodies and use it to calculate temperatures within the sediments as a function of time since emplacement. Depending on the thickness of these igneous bodies and the timing of sequential emplacement, the thermal history of a given locus in the basin can range from a simple extended period of higher temperatures to multiple episodes of peak temperatures separated by cooling intervals. The cooling of surface flood basalts, sills and dykes is capable of maintaining temperatures above the normal geothermal gradient temperatures for a few hundred thousand years, while large-scale underplating may influence temperatures for up to 10 million years. We conclude that any residual heat from the cooling of the Serra Geral igneous rocks has long since decayed to insignificant values and that present-day temperatures and heat flow are not affected. However, the burial of the sediments beneath the thick basalt cap caused a permanent temperature increase of up to 50°C in the underlying sediments since the beginning of the Cretaceous.     

The role of antelope trampling on scarp erosion in a hyper-arid environment, Skeleton Coast, Namibia

The role of animal trampling in a hyper-arid environment is evaluated. Field observations on fluvial terraces of the Uniab fan in Namibia suggest that animal impact on level surfaces with gravel armouring is minimal. However, animal trampling along tracks across scarp slopes results in scarp recess and initiate cutback development. With continued growth ephemeral fluvial processes become more dominant and obscure the animal impact. Animal trampling effects are pronounced in hyper-arid environments due to the low rates of other slope processes. However, it is argued that large herd migration may have contributed significantly to cutback development in other environments, especially in Africa, but may be very difficult to substantiate by landform analysis.     

季节性冻融对盐荒地水盐运移的影响及调控

季节性冻融是干旱区土壤盐碱化形成的主要驱动因子,但冻融过程中土壤水盐耦合关系及热量调控机理仍不清楚。通过分析2009年11月～2010年5月新疆玛纳斯河流域典型盐荒地季节性冻融过程中土壤剖面160 cm以内的水分、盐分和温度动态变化,探讨了不同土层冻融过程中水热盐的耦合关系。结果表明：土壤最大冻结深度为150 cm左右,表土层（0～40 cm）温度与气温关系密切;土壤剖面水分呈现“C”型垂直分布,表土层和底土层（100～160 cm）含水量较大,而心土层（40～100 cm）含水量不足10%,土层平均含水率在冻融前期增加了12.91%,而在初蒸期减少了10.01%;土壤剖面盐分在冻结期和初蒸期表聚作用明显,心土层和底土层含盐量稳定,土壤剖面含盐量表现为“积盐-脱盐-再积盐”的变化过程。水热盐之间具有高度协同性,心土层和底土层表现为水盐相随、而表土层为水去盐留的耦合特征,热量传输是调控水盐运移的关键因素。     

Modeling habitat use of the threatened and endemic mara (Dolichotis patagonum,Rodentia, Caviidae) in agricultural landscapes of Monte Desert

Effective management of natural populations depends heavily on the capacity for understanding and predicting their habitat requirements. For endemic and threatened species like the mara (Dolichotis patagonum), this information is extremely necessary for populations survival. I investigated and constructed a mathematical habitat model for the mara, with the capacity to predict the probability of finding animals in a particular environment. In the Monte Desert, maras prefer habitats with low shrub density and high percentage of bare soil. The area used by each couple of maras was 7.73 ha and shows an aggregation pattern. Contrary to expectation, about 94% of these areas were in habitats created by human activities. Grazed, burned and crop areas seem to be prefered by maras when natural open habitat disappear. This information and the results of habitat requirements can be used to monitor the status of mara populations and predict potential population extinctions according to habitat variables.     

城镇化进程中的空间扩张和土地利用控制

随着中国快速大规模的城镇化进程,城镇人口和产业集聚带来的就业岗位、基础设施、住房和公共服务设施的矛盾日益加剧,而城镇空间的快速扩张和蔓延式发展又成为众多矛盾的焦点。本文从规划理论和经济学理论出发分析了城镇空间扩张的内在动因,通过综述英美日等国家针对城镇空间扩张而采取的土地利用控制政策的经验提出了对策建议,并通过比较研究探讨了城市土地利用的合理标准问题。研究表明,资源环境条件是城镇密度的先决条件,基于亚洲大部分国家的资源环境基础和发展中国家的实际情况,集约化的城镇空间是我国最现实、最合理的选择;交通模式、土地开发模式、住宅开发模式、道路交通税制等是影响城镇密度的关键因素,因此,公共交通比例、住宅开发形式的选择等是对城镇空间密度进行调控的重要手段;城镇密度(人均土地利用指标)的最佳标准应根据交通模式、土地开发模式、住宅开发模式等条件的不同而区别确定。欧美研究学者提出的紧凑型发展模式下的城镇合理人口密度大致在70~150人/hm²之间。基于分析和比较,本研究建议集合住宅比例在80%以上的我国大中城市的人均城镇土地利用指标采用人均80~105 m²的标准,并应在实施过程中从严控制。     

Scale-dependent patterns of abundance and habitat use by cormorants in arid Australia and the importance of nomadism

We investigated the ways in which cormorants (Phalacrocorax spp.) acquire behavioural cues from unpredictable habitats in arid Australia, using 10 years of temporal data on abundance at one wetland, fine-grained habitat and microhabitat use at two wetlands, and broad-scale spatial data from aerial surveys across north-west New South Wales. Abundances were highly variable and cormorants were aggregated at every temporal and spatial scale of observation. Cormorants were associated with short-term patches of food, and apparently travel frequently in a quest for newly formed patches. Movements and abundance of cormorants are linked to boom periods of their prey, and, like many Australian waterbirds, cormorants would benefit from improved water management practices.     

Qualitative GIS and the visualization of narrative activity space data

Qualitative activity space data, i.e. qualitative data associated with the routine locations and activities of individuals, are recognized as increasingly useful by researchers in the social and health sciences for investigating the influence of environment on human behavior. However, there has been little research on techniques for exploring qualitative activity space data. This research illustrates the theoretical principles of combining qualitative and quantitative data and methodologies within the context of geographic information systems (GIS), using visualization as the means of inquiry. Through the use of a prototype implementation of a visualization system for qualitative activity space data and its application in a case study of urban youth we show how these theoretical methodological principles are realized in applied research. The visualization system uses a variety of visual variables to simultaneously depict multiple qualitative and quantitative attributes of individuals' activity spaces. The visualization is applied to explore the activity spaces of a sample of urban youth participating in a study on the geographic and social contexts of adolescent substance use. Examples demonstrate how the visualization can be used to explore individual activity spaces to generate hypotheses, investigate statistical outliers, and explore activity space patterns among subject subgroups.     

基于土地利用格局重建的区域生境质量时空变化分析

区域生境质量决定了区域内生物多样性状况,是生态系统服务功能和生态系统健康程度的重要体现,生境质量变化研究对区域生态安全具有重要的意义,重建区域生境质量空间格局可以还原历史时期的生态环境本底,为揭示区域生态环境质量演变规律提供科学支撑。选取高程、坡度、坡向、GDP、人口、温度、降雨量、河流距离、城市距离和海岸线距离10个土地利用变化驱动因子,构建CA-Markov模型参数,模拟得到历史土地利用空间数据。在此基础上,运用InVEST模型重建泛长三角地区生境质量空间格局,并对计算得到的生境退化度指数和生境质量指数进行等级划分与统计分析。结果表明：① 土地利用模拟精度验证结果显示Kappa系数为0.88,土地利用空间格局重建方法可行,可以在此基础上开展生境质量模拟研究。② 泛长三角地区1975—2010年生境退化度逐期上升,生境退化等级在空间分布上呈圈层递变分布规律。生境质量则表现为逐期下降,高值区主要分布于山区,低值区大部分位于建成区;1975—2010年期间,低值区逐渐向周边高值区域演变,生境高值区域趋于破碎化。③ 1975—2010年生境质量时空变化特征表明：生境质量差等级区域,其生境难以修复,维持原状居多;生境质量较差等级区域易继续恶化,且易发生在建成区周边区域,占比为研究区总面积的6.40%;生境等级为良好和优等的区域,其生境等级易转换为差等和较差等级,使得该区域的生境破碎化,该类型的面积占比为研究区总面积的5.68%。④ 1975—2010年期间,研究区土地利用变化显著,对生境质量造成了巨大的影响;研究区生境质量逐期变差,其生境质量等级位于较差及以下区域面积占比均达到了60%以上,建设用地为生境质量最大的威胁因子。     

Disentangling late-Holocene climate and land use impacts on an Austrian alpine lake using seasonal temperature anomalies,ice-cover,sedimentology, and pollen tracers

Major and trace elements, minerals and grain-size were analysed from a sediment core covering the last 4,000 years of an Austrian Alpine lake (Oberer Landschitzsee, ObLAN, 2,076 m a.s.l.). These analyses were combined with autumn and spring temperature anomalies and ice-cover estimated from a diatom and chrysophyte cyst, thermistor-based regional calibration dataset and selected pollen markers published previously. Diatom-inferred pH (Di-pH) and DOC (Di-DOC) completed the multi-proxy approach, which, together with ordination techniques (PCA and RDA), helped (1) to confirm proposed climatic patterns and hypotheses, and (2) to disentangle the complex interactions between climatic and anthropogenic impacts. Shifts in chemical and physical weathering, erosion, production, lake stratification, redox potentials and air pollution were the major processes that have affected Oberer Landschitzsee in relation to climate, lake/catchment interactions, and human impact. Geochemistry supported the finding that the four waves of high-altitude land use (Early to Middle Bronze, ca. 1,800–1,300 B.C.; Late Bronze to Hallstatt, ca. 1,000–500 B.C.; Celtic to Roman, ca. 300 B.C.–400 A.D.; and Medieval, ca. 1,000–1,600 A.D.) were coupled mainly with warm periods. Increased production, onset of lake stratification, and the deterioration of hypolimnetic oxygen conditions were the major changes governing in-lake processes during climate warming. They resulted in specific element assemblages associated with organic matter accumulation (Br), oxygen depletion (As, Ga, Cu, S), and changes in redox (Fe/Mn). The Se/Di-DOC ratio was introduced to track shifts between in-lake production and allochthonous sources. Nutrient loading from pastures, coupled with climate warming, could explain that in-lake production was highest during Roman and Medieval land use. Lithogenic elements mainly originated from chemical weathering of silicate bedrock and they increased when intense land-use was coupled with climate deterioration and/or increased humidity. These perturbations were highest during a High Medieval climate fluctuation around 1,000 A.D. The association of sand with LOI and C/N and the decoupling of sand from quartz and feldspar separates erosion from physical weathering. Di-DOC, S, and C/N showed hybrid characters in relation to climate and human impact. The mineral proportions indicated gradients in relation to weathering, snow-cover and running waters, as well as vegetation. Air pollution by metallurgic industries, starting during the High Medieval and culminating during the Late Medieval, caused lead accumulation and could have contributed to As and S enrichment. Corresponding features in the distribution of selected elements and pollen tracers, as well as changes in mineral proportions, supported the hypotheses of shifts in seasonal climate and an overall trend towards more continental climate conditions since Medieval times.     

基于区际负外部性理论的海岸带空间用途管制研究

海岸带是陆海相互作用强烈的特殊界面,其空间利用的负外部性具有典型的跨区域特征,需要以全局性、整体性、系统性的思维实施用途管制。本文引入区际负外部性理论,将研究对象从空间和空间利用转到伴随空间利用所产生的人地（海）关系的演变过程。首先,梳理海岸带空间利用区际负外部性的几种典型表现形式,进而构建海岸带区域系统,并明确了系统间的作用关系;其次,从区域系统作用的视角阐述海岸带空间用途管制的作用机制和具体手段;最后,提出政策建议,以期为海岸带空间用途管制的制度完善提供理论支撑和决策支持。