天津市滨海新区湿地景观格局变化及驱动力分析

湿地是生态系统的重要组成部分,是人类最重要的生存环境之一。天津滨海新区拥有丰富的湿地资源,但近年来随着经济的发展,人类活动的增强及相关政策的执行,湿地资源受到严重威胁。为全面掌握滨海新区近年来的湿地景观格局动态变化历程,本文以1986年、1996年、2006年和2016年TM遥感影像为主要数据源,运用遥感等技术手段,对滨海新区近30年来湿地景观格局时空演化进行动态分析、质心分析及指数分析,并简要讨论了湿地景观变化的主要驱动因子。结果表明：近30年间滨海新区湿地退化情况严重,累计退化面积达524.762 km²,其中2006?—?2016年湿地面积减幅最大,高达407.947 km²,减少区域集中分布在环渤海地带的淤泥质沙滩和浅海水域,转化后类型以建设用地为主。景观动态分析及质心分析结果表明：景观整体变化特征为破碎度逐渐增强、景观形状日趋复杂、景观生态功能日益减弱、景观分布向均衡化发展,整体湿地质心不断向内陆推移。驱动力分析结果显示：经济发展、人口增长和政策调控等人为因素是该时期景观格局变化的主要驱动因素。     

景观生态学在公路景观环境评价中的应用

公路景观环境评价研究是我国公路建设中的新课题，景观生态学的发展为公路景观环境评价研究提供了新理论、方法和技术手段。分析了景观生态学研究内容、方法特点，提出了从景观生态价值、美学质量、视觉容量和景观安全格局4个方面对公路景观环境进行评价，并探讨了具体评价过程，该思想对公路战略环境评价和环境影响后评价也具有启示意义。     

Feeding over the 24-h cycle: dietary flexibility of cathemeral collared lemurs (<Emphasis Type="Italic">Eulemur collaris</Emphasis>)

Animals show specific morphological, physiological and behavioural adaptations to diurnal or nocturnal activity. Cathemeral species, i.e. animals with activities distributed over the 24-h period, have to compromise between these specific adaptations. The driving evolutionary forces and the proximate costs and benefits of cathemerality are still poorly understood. Our goal was to evaluate the role of predator avoidance, food availability and diet quality in shaping cathemeral activity of arboreal mammals using a lemur species as an example. For this, two groups of collared lemurs, Eulemur collaris, were studied for 14 months in the littoral forest of southeastern Madagascar. Data on feeding behaviour were collected during all-day and all-night follows by direct observation. A phenological transect containing 78 plant species was established and monitored every 2 weeks to evaluate food availability during the study period. Characteristics of food items and animal nutritional intake were determined via biochemical analyses. The ratio of diurnal to nocturnal feeding was used as response variable in the analyses. The effects of abiotic environmental variables were removed statistically before the analyses of the biotic variables. We found that diurnal feeding lasted longer during the hot–wet season (December–February), whereas nocturnal feeding peaked during the hot–dry and cool–wet seasons (March–August). Although the lemurs foraged mostly in lower forest strata during daylight and used emergent trees preferably at night, the variables which measured animal exposure to birds of prey failed to predict the variation of the ratio of diurnal/nocturnal feeding. Ripe fruit availability and fiber intake are the two variables which best predicted the annual variation of the lemur diurnality. The data indicate that feeding over the whole 24-h cycle is advantageous during lean periods when animals have a fibre-rich, low-quality diet.     

Thresholds in Songbird Occurrence in Relation to Landscape Structure

Abstract:  Theory predicts the occurrence of threshold levels of habitat in landscapes, below which ecological processes change abruptly. Simulation models indicate that below critical thresholds, fragmentation of habitat influences patch occupancy by decreasing colonization rates and increasing rates of local extinction. Uncovering such putative relationships is important for understanding the demography of species and in developing sound conservation strategies. Using segmented logistic regression, we tested for thresholds in occurrence of 15 bird species as a function of the amount of suitable habitat at multiple scales (150–2000-m radii). Suitable habitat was defined quantitatively based on previously derived, spatially explicit distribution models for each species. The occurrence of 10 out of 15 species was influenced by the amount of habitat at a landscape scale (≥500-m radius). Of these species all but one were best predicted by threshold models. Six out of nine species exhibited asymptotic thresholds; the effects of habitat loss intensified at low amounts of habitat in a landscape. Landscape thresholds ranged from 8.6% habitat to 28.7% (     = 18.5 ± 2.6%[95% CI]). For two species landscape thresholds coincided with sensitivity to fragmentation; both species were more likely to occur in large patches, but only when the amount of habitat in a landscape was low. This supports the fragmentation threshold hypothesis. Nevertheless, the occurrence of most species appeared to be unaffected by fragmentation, regardless of the amount of habitat present at landscape extents. The thresholds we identified may be useful to managers in establishing conservation targets. Our results indicate that findings of landscape-scale studies conducted in regions with relatively high proportions of habitat and low fragmentation may not be applicable in regions with low habitat proportions and high fragmentation.     

农田生态系统中作物—昆虫—杂草的消长与农业环境

通过水旱作物轮换种植，探索与利用作物—昆虫（害虫和益虫）—杂草三大群落的消长与变迁规律，去发展生产，保持农田生态平衡，优化农业生态环境，最大限度地提高作物产量。     

土壤—植物系统中的镉研究进展

镉是土壤-植物系统中毒性最强的重金属之一，由镉产生的环境污染问题也日趋严重。近20年来，世界各国对镉在土壤-植物系统中的形态、转化、分布和毒害机理等都进行了广泛深入的研究本文对这些研究取得的成果和存在的分歧进行了综合评述，并提出对镉污染土壤进行综合治理的措施．     

森林景观格局研究中的尺度效应

以TM影像和野外调查为数据源,以3S技术为研究手段,从研究区域不同的取样尺度入手,分析了尺度变化对区域景观格局研究的影响.结果表明,研究区景观斑块的数量、最大斑块面积与取样面积之间关系密切.取样面积对景观格局的影响分析显示,在取样面积为研究区面积的70%时,景观多样性最高,平均多样性指数为1.854.当取样面积小于总面积的69%时,景观优势度指数呈增加的趋势.图4表2参16     

青海高原土壤拮抗性放线菌的生态分布

采用琼脂块法测定了分离自青海高原不同生态环境下的 1 007株代表性放线菌的拮抗性.结果表明:①供试菌中对大肠杆菌、金黄色葡萄球菌、假丝酵母、青霉、辣椒疫霉、西瓜枯萎菌、棉花枯萎菌及黄瓜枯萎菌有拮抗性的放线菌占供试菌总数的比率分别为 9. 1%、27. 2%、2. 1%、2. 6%、13. 8%、10. 1%、7. 1%及 7. 4%;在青海高原(西部)土壤的拮抗性放线菌中,抗细菌放线菌多于抗真菌放线菌,抗G+细菌的放线菌多于抗G-细菌放线菌,抗丝状真菌放线菌多于抗单细胞真菌放线菌.②耕作土壤中,拮抗性放线菌株数占放线菌总株数的百分率 (拮抗菌百分率 )是自然土壤的3. 5倍,且耕作土壤拮抗菌百分率按菜地(71. 7% ) >粮田(40. 6% ) >绿肥地(32. 8% ) >果园(25. 0% )的顺序排列.旱地土壤拮抗菌百分率明显高于水地.③不同类型土壤拮抗菌百分率均不同,且不同类型土壤拮抗菌百分率按黑钙土>栗钙土>灰钙土>砂土的顺序排列.④拮抗性放线菌的数量、拮抗菌百分率与土壤有机质、全氮、碱解氮、全磷及磷酸酶活性有关.其中有机质和全氮与拮抗性放线菌株数和拮抗菌百分率的相关性达极显著水平 (P<0. 01).抗细菌与抗真菌拮抗性放线菌的出现频率与土壤有机质、全氮及放线菌总数量的相关性分别达到了极显著(P<0. 01)与显著水平(P<0. 05),且土     

The spatial links tool: Automated mapping of habitat linkages in variegated landscapes

The removal, alteration and fragmentation of habitat in many parts of the world has led to a loss of biodiversity. Within the prevailing societal limitations the process is not easily reversed. Attempts are being made to minimise the fragmentation of remaining habitat by strategically reversing or managing habitat loss. Although their relative usefulness is a topic of debate among ecologists, habitat corridors are seen as one way of maintaining spatially dependent ecological processes within landscapes where habitat has been seriously depleted. Corridors can only be effective if they significantly contribute to the species sustaining processes of gene flow, resource access or the colonisation of vacant patches. We present a spatial habitat modelling methodology for evaluating the contribution and potential contribution of connecting paths to landscape connectivity. We have developed the spatial links tool (SLT), which maps link value across a region. The SLT combines connectivity measures from metapopulation ecology with the least cost path algorithm from graph theory, and can be applied to continuously variable landscape data. Combined with expert judgement, link value maps can be used to delineate habitat corridors. The approach capitalises on some synergies between ecological relevance and computational efficiency to produce an easily applied heuristic tool that has been successfully applied in NSW Australia.     

A Fine-Scale <Emphasis Type="Italic">k</Emphasis>−ε Model for Atmospheric Flow over Heterogeneous Landscapes

A multi-purpose model for small-scale atmospheric flows over heterogeneous landscapes is being developed. The aim of this research is to build a tool able to predict the dynamical (wind, turbulence) and diffusive (gases, particles) fields over landscapes characterised by heterogeneous plant cover. In its present stage of development the model is based on the numerical integration of neutral atmospheric flow equations, using an energy-dissipation closure scheme and over a domain that may include vegetation layers. Three validation cases of the model are presented: (i) response of the airflow to a change in surface roughness; (ii) airflow within and above a horizontally homogeneous plant canopy; (iii) airflow over two complex forest-to-clearing and clearing-to-forest transitions. All simulations provide results in good agreement with the experimental data, except for turbulent kinetic energy just after a clearing-to-forest transition. This result is not surprising for a statistical k– model in a flow region characterised by strong distorsion and intermittent turbulence. However the overall good performance of the model is promising for environmental research at fine scales over heterogeneous landscapes.