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91.
Ingemar Renberg Christian Bigler Richard Bindler Matilda Norberg Johan Rydberg Ulf Segerström 《Journal of environmental management》2009
Establishment of plans for environmental planning and management requires that a number of natural and societal factors must be taken into consideration. Insights into the inherent dynamics of nature as well as the role that past human activities have played for establishing the current condition of the landscape and the natural environment in general are essential. Many natural and man-made changes occur over time scales of decades or centuries, and these are difficult to comprehend without a historical perspective. Such a perspective can be obtained using palaeoecological studies, i.e. by geochemical and biological analyses of lake sediment and peat deposits. To illustrate the long-term dynamics of nature and particularly the role of man, we present here five case studies from Sweden concerning pollution, lake acidification, lake eutrophication, biodiversity, and landscape dynamics and conservation – topics of broad interests – and discuss benefits of including a longer time perspective in environmental management. 相似文献
92.
Indriķis Krams 《Behavioral ecology and sociobiology》2000,48(2):147-153
The risk of predation may influence the acquisition of energy and the feeding activity of animals. Feeding activity and body
reserves of wintering great tits Parus major in response to the priority to food access were studied in two areas differing in incidence of predators. The one-predator
area contained sparrowhawks Accipiter nisus only, whereas the two-predator area contained both sparrowhawks and pygmy owls Glaucidium passerinum, whose hunting periods overlap at dawn and dusk. In the two-predator area dominant great tits arrived at feeders significantly
later in the morning, and left earlier in the evening, than their subordinate flock-mates. Hence, feeding day length of dominants
was found to be significantly shorter. The reverse was true for the one-predator area. In addition, dominants carried significantly
greater reserves than subordinates in the area inhabited by two predators. Factors constraining subcutaneous energy reserves
were also studied in removal experiments. After the removal of dominant individuals, subordinate great tits did not reduce
their body reserves in the two predator area. In contrast, subordinate great tits significantly reduced evening body reserves
in the single-predator area. I concluded that the presence of the two predators increases unpredictability in feeding conditions
for great tits. Dominant individuals responded to this by shortening their feeding day and increasing body reserves at dusk.
Received: 8 December 1999 / Received in revised form: 15 March 2000 / Accepted: 31 March 2000 相似文献
93.
Rocky intertidal habitats frequently are used by humans for recreational, educational, and subsistence-harvesting purposes,
with intertidal populations damaged by visitation activities such as extraction, trampling, and handling. California Marine
Managed Areas, particularly regulatory marine reserves (MRs), were established to provide legal protection and enhancement
of coastal resources and include prohibitions on harvesting intertidal populations. However, the effectiveness of MRs is unclear
as enforcement of no-take laws is weak and no regulations protect intertidal species from other detrimental visitor impacts
such as trampling. The goal of this study was two-fold: (1) to determine impacts from human visitation on California mussel
populations (Mytilus californianus) and mussel bed community diversity; and (2) to investigate the effectiveness of regulatory MRs in reducing visitor impacts
on these populations. Surveys of mussel populations and bed-associated diversity were compared: (1) at sites subjected to
either high or low levels of human use, and (2) at sites either unprotected or with regulatory protection banning collecting.
At sites subjected to higher levels of human visitation, mussel populations were significantly lower than low-use sites. Comparisons
of mussel populations inside and outside of regulatory MRs revealed no consistent pattern suggesting that California no-take
regulatory reserves may have limited effectiveness in protecting mussel communities. In areas where many people visit intertidal
habitats for purposes other than collecting, many organisms will be affected by trampling, turning of rocks, and handling.
In these cases, effective protection of rocky intertidal communities requires an approach that goes beyond the singular focus
on collecting to reduce the full suite of impacts. 相似文献
94.
The theoretical concept, “asset specificity,” is applied to real data in the context of Danish nature conservation network
planning in order to produce illustrative examples of an economic measure of the network’s vulnerability to exogenous shocks
to the species composition. Three different measures of asset specificity are quantified from the shadow value of eliminating
a key species from the individual grid cells. This represents a novel approach and a different interpretation of the term,
as it is conventionally used as a qualitative indicator in the transaction cost economics literature. Apart from supplementing
existing cost measures with an indicator of risk associated with investments in protected areas, this study demonstrates how
the estimation and interpretation of various asset specificity measures for geographical areas may qualify policy makers’
choice of policy instrument in conservation planning. This differs from the more intuitive approach of basing policy instrument
choice solely on the rarity of the species in a given area. 相似文献
95.
关于建设项目对自然保护区生态影响专题评价的思考 总被引:1,自引:0,他引:1
建立自然保护区对保护生物圈及生物多样性具有十分重要的作用。我国已建立各种类型、不同级别的自然保护区2000多处。随着我国社会经济的发展,全国各地各类开发建设项目涌现,一些开发建设项目与自然保护区的保护要求发生矛盾。使开发建设项目避免或最大程度地减少对自然保护区的不利影响,做到保护与建设的双赢,是编写开发建设项目环境影响评价文件的一个重要内容。涉及自然保护区的开发建设项目一般要求编制对自然保护区影响的专题报告,本文根据工作实践,提出编制该类专题报告的主要内容及应注意的问题。 相似文献
96.
The coastline near the southern tip of Africa is characterized by large mobile dunes that are driven along wide beaches by
strong winds throughout the year. This results in the blockage of the river mouths causing severe flooding of the low-lying
farmland of the Agulhas Plain during the rainy winter season. Large parts of the driftsands were stabilized with the European
dune pioneer species Marram grass (Ammophila arenaria), which has proved highly invasive along the North American west coast. In order to establish the potential invasiveness
ofA. arenaria in South African coastal dune systems and its role in the succession of a large stabilization area, studies were carried
out on De Mond Nature Reverve. Using aerial photos, maps and planting records, the vegetation of sites of various ages were
sampled. By means of this chronosequence of stands, there is clear evidence that succession takes place at De Mond. Four communities
are distinguished, varying from recent plantings ofA. arenaria to mature dune thicket or dune fynbos (heath) vegetation. These relate to four different stages of succession,A. arenaria occurring in reduced abundance in the older communities. After 50 years, formerA. arenaria areas are usually covered by dense dune scrub and in some places even in asteraceous dune fynbos. Succession is most rapid
in sheltered, moist dune slacks, butA. arenaria remains vigorous in conditions favourable for its growht, i.e. on exposed, steep dune slopes with strong sand movement.A. arenaria does not appear to spread unaidedly at De Mond and has been successfully used for temporary dune stabilization. 相似文献
97.
Time discounting and the decision to protect areas that are near and threatened or remote and cheap to acquire 下载免费PDF全文
Paul R. Armsworth 《Conservation biology》2018,32(5):1063-1073
Should conservation organizations focus on protecting habitats that are at imminent risk of being converted but are expensive or more remote areas that are less immediately threatened but where a large amount of land can be set aside? Variants of this trade‐off commonly arise in spatial planning. I used models of land‐use change near a deforestation frontier to examine this trade‐off. The optimal choice of where to protect was determined by how decisions taken today accounted for ecological benefits and economic costs of conservation actions that would occur sometime in the future. I used an ecological and economic discount rate to weight these benefits and costs. A large economic discount rate favored protecting more remote areas, whereas a large, positive ecological discount rate favored protecting habitat near the current deforestation frontier. The decision over where to protect was also affected by the influence economic factors had on landowners' decisions, the rate of technological change, and ecological heterogeneity of the landscape. How benefits and costs through time are accounted for warrants careful consideration when specifying conservation objectives. It may provide a niche axis along which conservation organizations differentiate themselves when competing for donor funding or other support. 相似文献
98.
在西部大开发中 ,能源占有举足轻重的作用。我国西部的塔里木、准噶尔、吐 -哈、柴达木、鄂尔多斯、四川等六大含油气盆地含有丰富的天然气资源 ,储量大于 5 0 0× 10 8m3的 9个大气田中 ,西部就占 7个。中国天然气预测资源总量为 38× 10 12 m3,其中西部天然气预测资源量为 2 2 .4× 10 12 m3,占天然气预测资源总量的 5 8.9%。仅就西部的塔里木盆地而言 ,剩余可采储量为 3397× 10 8m3,按年产 12 0× 10 8m3计算 ,储采比为 2 8,塔里木盆地天然气有动态稳产 30年的储量保证 ,这对于“西气东输”工程的实施、西部经济的腾飞和可持续发展具有重要意义 相似文献
99.
Linnell JD Andersen R Kvam T Andrén H Liberg O Odden J Moa PF 《Environmental management》2001,27(6):869-879
Annual and seasonal home ranges were calculated for 47 Eurasian lynx in four Scandinavian study sites (two in Sweden and two
in Norway). The observed home ranges were the largest reported for the species, with study site averages ranging from 600
to 1400 km2 for resident males and from 300 to 800 km2 for resident females. When home range sizes were compared to the size of protected areas (national parks and nature reserves)
in Scandinavia, it was concluded that very few protected areas contained sufficient forest to provide space for more than
a few individuals. As a direct consequence of this, most lynx need to be conserved in the multiuse seminatural forest habitats
that cover large areas in Scandinavia. This conservation strategy leads to a number of conflicts with some land uses (sheep
and semidomestic reindeer herding, and roe deer hunters), but not all (forestry and moose harvest). Accordingly research must
be aimed at understanding the ecology of these conflicts, and finding solutions. 相似文献
100.
Ecological Compensation in Dutch Highway Planning 总被引:13,自引:0,他引:13
The ecological compensation principle was introduced by the Dutch government in 1993. This principle is designed to enhance
the input of nature conservation interests in decision-making on large-scale development projects and to counterbalance the
ecological impacts of such developments when implemented. This article evaluates the application of the Dutch compensation
principle in highway planning. Six current highway projects reveal consistent implementation of this principle, although provincial
policies on compensation and a national method for identifying compensation measures are still under development. As the planning
process has not yet been completed for all the projects, no general conclusions can be drawn on the impact of the compensation
principle on highway decision-making. Nevertheless, several examples show that the principle stimulates project initiators
to develop alternative routes or route sections in order to avoid or reduce ecological impacts and the need for coherent compensation
measures. If the compensation principle is to be properly implemented in the context of highway planning, particular attention
should be paid to the following aspects: (1) sequential assessment of overall project legitimacy and the necessity of intersecting
protected areas and compensation measures, (2) the initiator's attempts to avoid and mitigate ecological impacts in developing
alternative routes prior to compensation for impacts, and (3) the role of uncertain ecological impacts in identifying compensation
measures, especially those concerning habitat isolation. 相似文献