Landscape Analysis of the Forest-Tundra Ecotone in Rocky Mountain National Park,Colorado*

Landscapes in the ecotone between forest and tundra contain a mosaic of patches of trees, meadows, lakes, disturbed areas, and other features. The structure of this mosaic affects species habitat and potential ecotone response to global change. However, the alpine forest-tundra ecotone may be insensitive to climatic change if it is a climatic relict or is frequently disturbed. We used GIS and multivariate statistics to (1) analyze landscape structure in transects across the ecotone in Rocky Mountain National Park, (2) identify the major variants of forest-tundra ecotone, and (3) identify the influence of the environment and natural disturbances on variation in the landscape structure of the ecotone. There are six major types of ecotone varying in the amount of natural disturbances, permanent features (e.g., lakes), closed forest, patch forest, and krummholz. Variation is primarily related to slope, elevation, aspect, and geology associated with the morphology of the mountains and the disturbances they produce. The ecotone is not strongly structured by natural disturbances; thus, it may be more strongly controlled by and sensitive to climatic change than in areas where disturbance is more prevalent. Monitoring of potential ecotone response to global change is feasible, if tailored to the types of ecotone and their expected response.     

Current status,distribution, life cycle and ecology ofRhithrogena germanica Eaton, 1885 in Switzerland: Preliminary results (Ephemeroptera,Heptageniidae)

Rh. germanica is a European species that, due to human impacts, has progressively disappeared from its original territories and is now considered rare. In SwitzerlandRh. germanica has disappeared from the Aare, Broye and Kleine Emme rivers and is actually found in a limited reach of the River Rhine and some of its tributaries (Limmat, Sihl, Thur and Töss rivers).Rh. germanica is a univoltine species, hatching probably in summer. The emergence occurs from February to the beginning of April. It takes place on the water surface. Laboratory observations have shown that the subimaginal stage lasts four days.Rh. germanica occurs on different substrate types, ranging from stones and cobbles to pebbles and gravel. The larvae are more abundant in zones of erosion with coarse and porous sediments than in depositional zones with fine sediments and silts. They are most abundant in riffles with water velocities from 20 to 150 cm/sec. The species tolerates moderately organic-polluted waters.The particular strategy concerning growth and emergence ofRh. germanica is also discussed.     

Zooplankton distribution and abundance in saline lakes of Alberta and Saskatchewan,Canada

Zooplankton collections were made during 1985, 1986, 1988 and 1989 from 17 lakes in Saskatchewan and 3 in Alberta. Salinity ranged from 2.8 to 269 g L⁻¹ (total filtrable residue). A total of 35 species was present in four taxa: Anostraca (3 species), Cladocera (11), Copepoda (7) and Rotifera (14). Species richness was greatest at salinities <7 g L⁻¹ (15–16 species). Lakes with salinities between 7 and 100 g L⁻¹ generally had 6–8 zooplankton species, while the most saline lakes (>100 g L⁻¹) had 2–5 species. The largest concentrations of zooplankton occurred at <30 g L⁻¹, but some species (Brachionus plicatilis, Hexarthra polyodonta, Artemia franciscana, Diaptomus connexus) were abundant at salinities >50 g L⁻¹. Eurysaline species included the rotifersAsplanchna girodi (3–111 g L⁻¹),Brachionus plicatilis (13–146) andKeratella quadrata (2.8–103).Artemia franciscana (33–269—but absent from Big Quill Lake, 49–82),Daphnia similis (3–104).D. connexus (9–82),Diacyclops thomasi (3–72), andCletocamptus albuquerquensis (17 to 126—but never abundant in the plankton). About half the species were restricted to hyposaline waters (3–20 g L⁻¹), but some (Hexarthra fennica, Moina hutchinsoni, Hexarthra polyodonta) occurred only at intermediate salinities. The latter two species were also only present at high pH values (>9.2). There was a trend of decreasing species richness with increasing salinity. TWINSPAN classification of 94 lake samples (six parameters) based on zooplankton species abundances yielded a dendrogram with 14 ‘indicator’ species characteristic of seven lake groups related partly to a salinity gradient, but with other environmental factors such as water column depth, pH, Secchi disk transparency, water temperature and month sampled also influenced lake separation. *** DIRECT SUPPORT *** A02GG004 00002     

新形势下我国能源与生态安全保障研究

能源与生态安全是关系国家社会经济发展的基础性和战略性问题,煤炭作为我国主体能源在一次能源中的消费占比长期保持在60%以上,但我国煤炭资源保障能力不足,存在浅部资源已近枯竭、深部资源开采难度大、西部开发能力弱、绿色煤炭资源保障程度低、接替资源储量不足、煤系共伴生矿产勘查开发程度低等问题;另一方面,矿山环境治理是目前生态环境治理的主体,亟需加大治理力度来保障新时代的“绿水青山”,对以往矿山环境损伤的修复治理工作需要进一步加强,新采矿引发的环境问题要逐步实现开发与治理同步。基于当前主体能源与主要生态安全保障问题,提出了资源勘查和生态勘查具体方法与路径,提高我国能源与生态安全保障程度。     

Transborder political ecology of mangroves in Senegal and The Gambia

Existing studies of mangroves in Senegal and The Gambia have found net increases in mangrove tree cover at the national scale, but these do not accord with local accounts and explanations of loss. This paper utilizes remote sensing analysis and political ecology frameworks to assess local accounts of mangrove wood trafficking across the border between The Gambia and southern Senegal, which were encountered in conducting qualitative field research. The remote sensing results demonstrate overall increases in mangrove cover in The Gambia and in the Sine Saloum and Low Casamance estuaries in Senegal between 1988 and 2018, but also highlight greater declines in mangrove cover in Low Casamance in the 1990s—a period of heightened regional political conflict—and in particular areas of the estuary near the Gambian and Guinea-Bissauan borders. Focusing on political ecology’s attention to multiple scales of analysis, this paper addresses divergent interpretations of mangrove changes in the region, and how local accounts of destruction may not be fully captured by the scale of observation and analysis in remote sensing. The paper argues for greater attention to spatial and temporal variation in studies of mangrove dynamics, and greater consideration for how these patterns may result from confluences of political, social, and natural factors.     

海洋文化生态的保护与建设——以青岛渔盐古镇韩家村为例

文化的保护与建设已成为我国学术界关注的重要课题之一。伴随着海洋世纪的到来,海洋文化的保护与建设受到了越来越多的关注。为全面有效地保护海洋文化,有必要对我国海洋文化生态的保护建设问题进行深入解析。以青岛渔盐古镇韩家村为例,以海洋文化生态为视角,对韩家村海洋文化生态现状及其体系结构进行考察,并对其呈现的特征进行解析,对其保护建设过程中的存在问题、影响因素、保护建设路径进行分析,旨在以小见大,为我国海洋文化保护与建设提供参考性建议。     

Understanding pastoral mobility: the case of Senegalese Fulani

Based on a case study from Sahelian Senegal, this paper analyses how various actors perceive the importance of pastoral mobility and presents issues of importance for understanding the use of mobility among Fulani of Ferlo. One knowledge system is a scientific one, the 'new rangeland paradigm'. According to this, pastoral mobility is a means to balance variability in dryland resources; hence, 'nature' is the point of departure. Another knowledge system is local pastoral knowledge. For the pastoralists, the well-being of their animals is the point of departure and mobility is used to ensure that the livestock are in good condition. The paper shows that it is important to distinguish between mobility of pastoralists and of their herd; even though the pastoralists of northern Senegal have become semi-sedentary, their herds are still quite mobile. The pastoralists are willing to move around within a small territory, which they consider their place, but are unwilling to employ large-scale mobility themselves. Mobility is not of importance for their ethnic identity and some use paid herders to care for their livestock. By looking at both knowledge systems, we achieve a better understanding of pastoral mobility and how this may change in the future.     

FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND‐REDISTRIBUTION PROGRAM*

ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land‐reform programs. In this study we examine land‐redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross‐section of projects in these two locales we develop a political ecology of stymied land‐reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white‐owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land‐redistribution beneficiaries, as well as on an analysis of land‐use change in Limpopo Province.     

全新世中期7 ka前后降温事件对中国北方植被生态的影响

大量研究表明,随着气候变暖,全球生态环境发生了巨大变化。然而,在相对温暖的气候条件下,假若发生重大降温事件,生态环境尤其是植被生态会如何响应,值得深入探讨。利用近年来发表的全新世高分辨率古气候记录以及孢粉记录的植被变化,对全新世中期7 ka(1 ka=1000 cal.a B.P.)前后的降温事件及其对植被生态的影响进行了综合分析。结果表明,7 ka前后降温事件在北半球很大范围都有记录,在季风边缘区伴随着气候的干旱,而在西风主导的区域总体表现为气候湿润。中国北方季风区山地以及高纬度地区表现为建群种的变化,如阔叶树种的减少以及针叶树种的增加;在季风边缘区总体表现为干旱气候下植被盖度的降低;而在西北内陆山地高山区域表现为林线的降低或树种的变化,低山地区森林下限表现为森林成分的增加以及耐旱树种的减少;在山前草原和盆地荒漠草原区域,植被的响应表现为植被盖度的增加和喜湿成分的增加。降温直接影响湿度较大的高山地区的森林成分和林线高度,而在低山干旱半干旱地区,降温则通过抑制蒸发、增加有效湿度影响植被盖度和组成。由于不同钻孔年代的不确定性、不同植被类型对气候变化的敏感性不同等,不同区域发生植被转型的时间不尽一致。全新世中期7 ka降温事件的触发机制有待深入研究,可能与大型火山喷发以及太阳活动变化有关,夏季太阳辐射的持续降低以及地球系统内部反馈也是共同的原因。