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1.
Brian D. Smith A. K. M. Aminul Haque M. Shakhawat Hossain Anisuzzaman Khan 《Environmental management》1998,22(3):323-335
Platanista gangetica ) are threatened in Bangladesh from the effects of dams, large embankment schemes, dredging, fisheries bycatch, directed hunting,
and water pollution. Visual surveys of the section of the Jamuna River located between the divergence of the Old Brahmaputra
River and the confluence of the Padma River and the section of the Kushiyara River located between the Bangladesh–India border
and the confluence of the Korangi River recorded a sighting rate of 0.13 sightings/km (mean group size = 1.8 dolphins) and
0.08 sightings/km (mean group size = 3.8 dolphins), respectively. These sections of river were considered to be priority areas
for investigation because several water development projects have already been constructed and more are planned for the areas.
During the surveys we examined the remains of dolphins caught accidentally in plastic gillnets and observed fishermen catching
the fish species Clupisoma garua using dolphin oil and body parts as a fish attractor. Additional studies are needed to assess the status of dolphins and
effects of water development and fisheries bycatch. Feasibility studies should be conducted on designating dolphin/fish sanctuaries
and creating artificial habitat or enhancing existing habitat in eddy countercurrent scour pools to mitigate deleterious impacts.
The environmental requirements of river dolphins reflect the needs of productive and biotically diverse tropical rivers. 相似文献
2.
Influence of Social, Biophysical, and Managerial Conditions on Tourism Experiences Within the Great Barrier Reef World Heritage Area 总被引:1,自引:0,他引:1
N = 1475) traveling with tourism operations of different sizes who traveled to different sites completed surveys. Results indicated
that snorkelers who traveled with larger operations (more people and infrastructure) differed from those traveling with smaller
operations (few people and little on-site infrastructure) on benefits received and in the way that specific conditions influenced
their enjoyment. Benefits related to nature, escape, and family helped to define reef experiences. Conditions related to coral,
fish, and operator staff had a positive influence on the enjoyment of most visitors but, number of people on the trip and
site infrastructure may have the greatest potential as setting indicators. Data support the potential usefulness of visitor
input in applying the LAC concept to a marine environment where tourism and recreational uses are rapidly changing. 相似文献
3.
Accumulation of bacterial cells on a transparent electrode was controlled by applying an alternating potential. Live and
dead cells on a transparent electrode can be distinguished as blue and red cells, by staining with two fluorescent dyes, propidium
iodide (PI) and 4′, 6-diamidino- 2-phenylindole dihydrochloride (DAPI) and propidium iodide (PI), respectively. Cells of
the gram-negative marine bacterium, Vibrio alginolyticus attached to an indium/tin oxide (ITO) electrode were killed by applying a potential of 1.1 V versus saturated calomel electrode
in seawater. By applying –0.4 V, 73% of the cells on the ITO electrode were desorbed in 10 min. Changes in pH and generation
of chlorine were not observed after applying potentials in the range of –0.4∼1.2 V. After 21 h of immersion in V. alginolyticus cell suspension with the application of an alternating potential of 1.1 and –0.4 V, cells on the electrode were completely
killed and the cell number decreased to 20% of that of no potential. Elution of indium and tin was not observed after 10 days
application of alternating potential.
Received: 11 August 1998 / Accepted: 30 September 1998 相似文献
4.
Tiga Neya Akwasi. A. Abunyewa Oble Neya Benewende J-B Zoungrana Kangbeni Dimobe Hypolite Tiendrebeogo John Magistro 《Environmental management》2020,65(2):203-211
Agroforestry plays an important role in climate mitigation through atmospheric carbon removal by photosynthetic activity of tree. However, the carbon sequestration potential of smallholder’s agroforestry’s parklands is not well documented in Burkina Faso. Therefore, agroforestry parkland of smallholders’ farmers in three climatic zones was studied. Thirty household farmlands in each climatic zone representing about 35 ha were selected on which systematic woody species inventory and dendrometry data collections were undertaken. Nondestructive method using fitted allometrics equations was used to compute carbon stock. Sustainability analysis of carbon sequestration potential was done using ]0–10], ]10–40], and ]40–110 cm] diameter class as long term, medium term, and short term, respectively. The balance between marketable carbon value and the trade-off from tree conservation of three major crops was also analyzed. The results revealed 24.71 ± 5.84 tCO2 ha−1, 28.35 ± 5.84 tCO2 ha−1, and 33.86 ± 5.84 tCO2 ha−1 in Ouahigouya, Sapouy, and Bouroum-Bouroum at p < 0.1 respectively. Long- and short-term carbon sequestration potential was attributed to Ouahigouya with 1.82 and 68.03%, respectively. With, the medium term analysis Sapouy came first with 71.71% of total amount of carbon. The marketable carbon value was less than trade-off value resulting in keeping trees and crop production. The balance analysis revealed that carbon payment system promoted by REDD+ initiative will be profitable and compensable to smallholder farmers effort to plant and keep tree when the tCO2 ha−1 price will be around US$ 4.00. By taking into account farmers’ interests and profitability on carbon market will be the most relevant incentive method to enhance carbon stock in agroforestry parkland. 相似文献
5.
The ecological integrity of the Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle and A. Young) alliance is being severely interrupted by post-fire invasion of non-native annual grasses. To curtail this invasion, successful post-fire revegetation of perennial grasses is required. Environmental factors impacting post-fire restoration success vary across space within the Wyoming big sagebrush alliance; however, most restorative management practices are applied uniformly. Our objectives were to define probability of revegetation success over space using relevant soil-related environmental factors, use this information to model cost of successful revegetation and compare the importance of vegetation competition and soil factors to revegetation success. We studied a burned Wyoming big sagebrush landscape in southeast Oregon that was reseeded with perennial grasses. We collected soil and vegetation data at plots spaced at 30?m intervals along a 1.5?km transect in the first two years post-burn. Plots were classified as successful (>5?seedlings/m(2)) or unsuccessful based on density of seeded species. Using logistic regression we found that abundance of competing vegetation correctly predicted revegetation success on 51?% of plots, and soil-related variables correctly predicted revegetation performance on 82.4?% of plots. Revegetation estimates varied from $167.06 to $43,033.94/ha across the 1.5?km transect based on probability of success, but were more homogenous at larger scales. Our experimental protocol provides managers with a technique to identify important environmental drivers of restoration success and this process will be of value for spatially allocating logistical and capital expenditures in a variable restoration environment. 相似文献
6.
Zoning and applying Limits of Acceptable Change (LAC) are two promising strategies for managing tourism in Marine Protected
Areas (MPAs). Typically, these management strategies require the collection and integration of ecological and socioeconomic
data. This problem is illustrated by a case study of Koh Chang National Marine Park, Thailand. Biophysical surveys assessed
coral communities in the MPA to derive indices of reef diversity and vulnerability. Social surveys assessed visitor perceptions
and satisfaction with conditions encountered on snorkelling tours. Notably, increased coral mortality caused a significant
decrease in visitor satisfaction. The two studies were integrated to prescribe zoning and “Limits of Acceptable Change” (LAC).
As a biophysical indicator, the data suggest a LAC value of 0.35 for the coral mortality index. As a social indicator, the
data suggest that a significant fraction of visitors would find a LAC value of under 30 snorkellers per site as acceptable.
The draft zoning plan prescribed four different types of zones: (I) a Conservation Zone with no access apart from monitoring
or research; (II) Tourism Zones with high tourism intensities at less vulnerable reefs; (III) Ecotourism zones with a social
LAC standard of <30 snorkellers per site, and (IV) General Use Zones to meet local artisanal fishery needs. This study illustrates
how ecological and socioeconomic field studies in MPAs can be integrated to craft zoning plans addressing multiple objectives. 相似文献
7.
Environmental economists have long used surveys to gather information about people's preferences. A recent innovation in survey methodology has been the advent of web-based surveys. While the Internet appears to offer a promising alternative to conventional survey administration modes, concerns exist over potential sampling biases associated with web-based surveys and the effect these may have on valuation estimates. This paper compares results obtained from a travel cost questionnaire of visitors to Fraser Island, Australia, that was conducted using two alternate survey administration modes; conventional mail and web-based. It is found that response rates and the socio-demographic make-up of respondents to the two survey modes are not statistically different. Moreover, both modes yield similar consumer surplus estimates. 相似文献
8.
Spencer A. Peterson David P. Larsen Steven G. Paulsen N. Scott Urquhart 《Environmental management》1998,22(5):789-801
N = 11,076). Results were compared to a large, nonrandomly sampled data set for the same area compiled by Rohm and others and
contrasted with lake trophic state information published in the National Water Quality Inventory: 1994 Report to Congress
[305(b) report. Lakes across the entire Northeast were identified by EMAP data as 37.9% (±8.4%) oligotrophic, 40.1% (±9.7%)
mesotrophic, 12.6% (±7.9%) eutrophic, and 9.3% (±6.3%) hypereutrophic. Lakes in the ADI and NEU generally are at a low, nearly
identical trophic state (96% oligotrophic/mesotrophic), while those in the CLP are much richer (45% eutrophic). EMAP results
are similar to results of the Rohm data set across the entire region. In the CLP, however, EMAP identified approximately 45%
of the lakes as eutrophic/hypereutrophic, while the Rohm data set identified only 21% in these categories. Across the entire
Northeast, the 305(b) report identified a much higher proportion (32.2%) of lakes in eutrophic condition and a much smaller
proportion (19.8%) in oligotrophic condition than did the EMAP survey data (12.5% ± 7.9% and 37.9% ± 8.5%, respectively).
Probability sampling has several advantages over nonrandom sampling when regional resource condition assessment is the goal. 相似文献
9.
Phleum pratense and Poa pratensis were significantly lower (P ≤ 0.001) on plots with more than 250 ppm copper. Above-ground biomass of Phleum pratense was also significantly lower on plots with copper levels above 250 ppm. Decreased mean grass density was found on plots with
pH < 6.4, but the only statistically significant difference was for Juncus balticus, which had increased density on plots with pH < 6.4. In contrast to the clear impacts of trace metals and pH on vegetation,
other site characteristics did not alter measured vegetation characteristics. 相似文献
10.
ROBERT N. LEHMAN KAREN STEENHOF MICHAEL N. KOCHERT LESLIE B. CARPENTER 《Environmental management》1999,23(3):409-417
Buteo regalis ), northern harriers (Circus cyaneus), burrowing owls (Athene cunicularia), and short-eared owls (Asio flammeus) inside and outside a military training site in the Snake River Birds of Prey National Conservation Area, southwestern Idaho.
The Orchard Training Area is used primarily for armored vehicle training and artillery firing by the Idaho Army National Guard.
Relative abundance of nesting pairs inside and outside the training site was not significantly different from 1991 to 1993
but was significantly higher on the training site in 1994 (P ≤ 0.03). Nesting success varied among years but was not significantly different inside and outside the training site (P > 0.26). In 1994, short-eared owl and burrowing owl nests were significantly closer to firing ranges used early in the spring
before owls laid eggs than were random points (P < 0.001). In 1993, distances from occupied burrowing owl nests to firing ranges used early in the year were similar to those
from random points to the same firing ranges (P = 0.16). Military activity contributed to some nesting failures from 1992 to 1994, but some pairs nested successfully near
military activity. 相似文献
11.
12.
Tole L 《Environmental management》2001,28(4):455-467
Jamaica is a small island that is losing its forest cover at a rapid rate. Due to the dependency of its largely poor population
on the many services and functions its forests provide, this loss threatens to have substantial socioeconomic and ecological
consequences for the country. Despite these basic facts, the problem of Jamaican deforestation has received very little attention
from the scientific community. This article presents results of an island-wide, satellite-based study of forest change for
Jamaica for the period 1987–1992, which was supplemented by a field trip to the island in 1999 to assess the overall accuracy
of the estimate. Landsat MSS images, which are available only up until 1992, have proved to be an invaluable and cost-effective
resource for mapping forest change in the tropics, particularly in large areas. A supervised classification indicates that
Jamaica experienced an average annual deforestation rate of 3.9% for this period, a figure higher than existing estimates
based on partial ground surveys but lower than the FAO's 1990 Tropical Forest Assessment of 5.3% for 1981–1990. Deforestation
estimates for Jamaica's 14 parishes are also presented, based on the integration of satellite-derived forest classification
maps with a parish administrative boundaries map of the island in a GIS. A correlation analysis between parish deforestation
estimates and socioeconomic and land use/quality indicators derived from official sources suggests that deforestation is occurring
most rapidly in highly populated areas possessing large numbers of small farmers who live and work under resource-poor conditions.
By providing a sense of the magnitude of and main forest loss hotspots, it is hoped that these national and subnational level
forest estimates will draw scientific attention to the problem of deforestation on the island. In addition, the socioeconomic
analysis may provide policy-makers and planners with some sense of the relative contribution of underlying driving process
in this deforestation as a first step toward the creation of effective social programs to combat the problem. 相似文献
13.
Spermophilus townsendii ) prey. These changes could occur directly or as a result of changes in the vegetation available as food and cover for the
ground squirrels. We assessed the effects of long-term tracking by armored vehicles by comparing 9-ha areas in sagebrush (Artemisia tridentata) -dominated shrubsteppe and bluegrass (Poa secunda) -dominated grasslands subjected to low-intensity tracking for ∼50 years with others that had not been tracked. We did not
detect any effect on ground squirrel population dynamics associated with long-term tracking. Although densities of adults
and juveniles tended to be higher in the areas exposed to such tracking, we attribute this difference to other factors that
varied spatially. To determine short-term (two-year) effects, we experimentally tracked two sagebrush and two grassland sites
with an M-1 tank after animals had begun their inactive season. In the following two active seasons we monitored squirrel
demography and behavior and vegetative characteristics on the experimentally tracked sites and compared the results with control
sites. Although we experimentally tracked ∼33% of the surface of each of four sites where ground squirrel densities were assessed,
the tracking had a detectable effect only on some herbaceous perennials and did not influence ground squirrel densities or
behavior significantly during the subsequent two active seasons. We conclude that tracking after the start of the inactive
season is likely to influence ground squirrel demography or behavior only if vegetation cover is substantially changed by
decreasing coverage of preferred food plants or increasing the coverage of annual grasses and forbs that are succulent for
only a short time each year. 相似文献
14.
Stream-riparian ecosystems are dynamic and complex entities that can support high levels of bird assemblage abundance and
diversity. The myriad patches (e.g., aquatic, floodplain, riparian) found in the riverscape habitat mosaic attract a unique
mixture of aquatic, semiaquatic, riparian, and upland birds, each uniquely utilizing the river corridor. Whereas standard
morning bird surveys are widely used across ecosystems, the variety of bird guilds and the temporal habitat partitioning that
likely occur in stream-riparian ecosystems argue for the inclusion of evening surveys. At 41 stream reaches in Vermont and
Idaho, USA, we surveyed bird assemblages using a combination of morning and evening fixed-width transect counts. Student’s
paired t-tests showed that while bird abundance was not significantly different between morning and evening surveys, bird assemblage
diversity (as measured by species richness, Shannon-Weiner’s index, and Simpson’s index) was significantly higher in the morning
than in the evening. NMS ordinations of bird species and time (i.e., morning, evening) indicated that the structure of morning
bird assemblages was different from that of evening assemblages. NMS further showed that a set of species was only found in
evening surveys. The inclusion of evening counts in surveying bird assemblages in stream-riparian ecosystems has important
experimental and ecological implications. Experimentally, the sole use of morning bird surveys may significantly underestimate
the diversity and misrepresent the community composition of bird assemblages in these ecosystems. Ecologically, many of the
birds detected in evening surveys were water-associated species that occupy high trophic levels and aerial insectivores that
represent unique aquatic-terrestrial energy transfers. 相似文献
15.
Marko S. Markov 《The Environmentalist》2012,32(2):121-130
In 1988 I published a paper “Electromagnetic fields—a new ecological factor” (Markov 1988). There was no internet and very few cell phones were available. It was not even fear from the hazard of the power lines.
However, I want to cite the beginning of this paper: “The contemporary conditions of life put man in dependence of the complex
of physical influences on the environment and in the first place—of the electromagnetic fields. The rapid development of science
and technology has resulted in the introduction of many new devices and technologies in industry, agriculture, and everyday
life. On the other hand, during their phylogenetic and ontogenic development, the living organisms are continuously exposed
to the influence of different biotic and abiotic factors. The physical factors are included in the first group, and the entire
evolution of life is connected with an adaptation to the action of these factors.” Could I repeat this statement nearly a
quarter of century later? Sure, I will. The only difference would be that I will speak not only for electromagnetic fields,
but for green-house effects, global warming, volcano eruption, and radiation disasters. I would also discuss the noise and
vibration to which people are exposed from early days to the very end of their life traveling with private vehicles or public
transport. 相似文献
16.
Bhatnagar YV Wangchuk R Prins HH Van Wieren SE Mishra C 《Environmental management》2006,38(6):934-941
An emerging conflict with Trans-Himalayan pastoral communities in Ladakh’s Changthang Plateau threatens the conservation prospects
of the kiang (Equus kiang) in India. It is locally believed that Changthang’s rangelands are overstocked with kiang, resulting in forage competition
with livestock. Here, we provide a review and preliminary data on the causes of this conflict. Erosion of people’s tolerance
of the kiang can be attributed to factors such as the loss of traditional pastures during an Indo-Chinese war fought in 1962,
immigration of refugees from Tibet, doubling of the livestock population in about 20 years, and increasing commercialization
of cashmere (pashmina) production. The perception of kiang overstocking appears misplaced, because our range-wide density estimate of 0.24 kiang
km−2 (± 0.44, 95% CL) is comparable to kiang densities reported from Tibet. A catastrophic decline during the war and subsequent
recovery of the kiang population apparently led to the overstocking perception in Ladakh. In the Hanle Valley, an important
area for the kiang, its density was higher (0.56 km−2) although even here, we estimated the total forage consumed by kiang to be only 3–4% compared to 96–97% consumed by the large
livestock population (78 km−2). Our analysis nevertheless suggests that at a localized scale, some herders do face serious forage competition from kiang
in key areas such as moist sedge meadows, and thus management strategies also need to be devised at this scale. In-depth socioeconomic
surveys are needed to understand the full extent of the conflicts, and herder-centered participatory resolution needs to be
facilitated to ensure that a sustainable solution for livelihoods and kiang conservation is achieved. 相似文献
17.
Stafford JD Reinecke KJ Kaminski RM Gerard PD 《Journal of environmental management》2006,78(4):353-361
Large-scale sample surveys to estimate abundance and distribution of organisms and their habitats are increasingly important in ecological studies. Multi-stage sampling (MSS) is especially suited to large-scale surveys because of the natural clustering of resources. To illustrate an application, we: (1) designed a stratified MSS to estimate late autumn abundance (kg/ha) of rice seeds in harvested fields as food for waterfowl wintering in the Mississippi Alluvial Valley (MAV); (2) investigated options for improving the MSS design; and (3) compared statistical and cost efficiency of MSS to simulated simple random sampling (SRS). During 2000-2002, we sampled 25-35 landowners per year, 1 or 2 fields per landowner per year, and measured seed mass in 10 soil cores collected within each field. Analysis of variance components and costs for each stage of the survey design indicated that collecting 10 soil cores per field was near the optimum of 11-15, whereas sampling >1 field per landowner provided few benefits because data from fields within landowners were highly correlated. Coefficients of variation (CV) of annual estimates of rice abundance ranged from 0.23 to 0.31 and were limited by variation among landowners and the number of landowners sampled. Design effects representing the statistical efficiency of MSS relative to SRS ranged from 3.2 to 9.0, and simulations indicated SRS would cost, on average, 1.4 times more than MSS because clustering of sample units in MSS decreased travel costs. We recommend MSS as a potential sampling strategy for large-scale natural resource surveys and specifically for future surveys of the availability of rice as food for waterfowl in the MAV and similar areas. 相似文献
18.
During the post-World War II era, the Mojave Desert Region of San Bernardino County, California, has experienced rapid levels
of population growth. Over the past several decades, growth has accelerated, accompanied by significant shifts in ethnic composition,
most notably from predominantly White non-Hispanic to Hispanic. This study explores the impacts of changing ethnicity on future
development and the loss of open space by modeling ethnic propensities regarding family size and settlement preferences reflected
by U.S. Census Bureau data. Demographic trends and land conversion data were obtained for seven Mojave Desert communities
for the period between 1990 and 2001. Using a spatially explicit, logistic regression-based urban growth model, these data
and trends were used to project community-specific future growth patterns from 2000 to 2020 under three future settlement
scenarios: (1) an “historic” scenario reported in earlier research that uses a Mojave-wide average settlement density of 3.76
persons/ha; (2) an “existing” scenario based on community-specific settlement densities as of 2001; and (3) a “demographic
futures” scenario based on community-specific settlement densities that explicitly model the Region’s changing ethnicity.
Results found that under the demographic futures scenario, by 2020 roughly 53% of within-community open space would remain,
under the existing scenario only 40% would remain, and under the historic scenario model the communities would have what amounts
to a deficit of open space. Differences in the loss of open space across the scenarios demonstrate the importance of considering
demographic trends that are reflective of the residential needs and preferences of projected future populations. 相似文献
19.
We sent out a targeted questionnaire to organizations and private individuals across the UK that have expressed an interest
in squirrel management and conservation. Respondents were asked to evaluate shooting, trapping, poisoning and immunocontraception
(IMC), according to their perceived efficacy, cost efficiency, and whether they were considered to be humane. The majority
of both professionals and enthusiasts indicated support for grey squirrel control to help conserve red squirrels and to reduce
economic damage to timber crops. Respondents\' comparative evaluations of current forms of control showed that trapping is
the most acceptable method. When IMC is compared with the other methods, it was considered to be more humane and acceptable.
In contrast, poisoning was seen as humane or acceptable by the fewest respondents. Furthermore, poisoning elicited the greatest
difference in opinion between the professional and enthusiast groups. This difference (34\%) may be interpreted partly as
concern over the type of death that results from poisoning and partly as due to the possibility of poisoning nontarget species.
Our findings indicate a need for more public information regarding secondary poisoning hazards to other species and their
predators. Interest and concern about squirrel control correlated with the overlap between contemporary areas of distribution
of the two species. It is these areas where consultation and education programs about control methods should be targeted.
This research indicates that there would be support for grey squirrel control using IMC from both lay and professional interest
groups. It demonstrates the existence of a sound basis for constructive dialog that can lead to the design and implementation
of acceptable and efficient control strategies. 相似文献
20.
Rita JC Gama-Rodrigues EF Gama-Rodrigues AC Polidoro JC Machado RC Baligar VC 《Environmental management》2011,48(1):134-141
Agroforestry systems (AFSs) have an important role in capturing above and below ground soil carbon and play a dominant role
in mitigation of atmospheric CO2. Attempts has been made here to identify soil organic matter fractions in the cacao-AFSs that have different susceptibility
to microbial decomposition and further represent the basis of understanding soil C dynamics. The objective of this study was
to characterize the organic matter density fractions and soil size fractions in soils of two types of cacao agroforestry systems
and to compare with an adjacent natural forest in Bahia, Brazil. The land-use systems studied were: (1) a 30-year-old stand
of natural forest with cacao (cacao cabruca), (2) a 30-year-old stand of cacao with Erythrina glauca as shade trees (cacao + erythrina), and (3) an adjacent natural forest without cacao. Soil samples were collected from 0-10 cm
depth layer in reddish-yellow Oxisols. Soil samples was separated by wet sieving into five fraction-size classes (>2000 μm,
1000–2000 μm, 250–1000 μm, 53–250 μm, and <53 μm). C and N accumulated in to the light (free- and intra-aggregate density
fractions) and heavy fractions of whole soil and soil size fraction were determined. Soil size fraction obtained in cacao
AFS soils consisted mainly (65 %) of mega-aggregates (>2000 μm) mixed with macroaggregates (32–34%), and microaggregates (1–1.3%).
Soil organic carbon (SOC) and total N content increased with increasing soil size fraction in all land-use systems. Organic
C-to-total N ratio was higher in the macroaggregate than in the microaggregate. In general, in natural forest and cacao cabruca
the contribution of C and N in the light and heavy fractions was similar. However, in cacao + erythrina the heavy fraction
was the most common and contributed 67% of C and 63% of N. Finding of this study shows that the majority of C and N in all
three systems studied are found in macroaggregates, particularly in the 250–1000 μm size aggregate class. The heavy fraction
was the most common organic matter fraction in these soils. Thus, in mature cacao AFS on highly weathered soils the main mechanisms
of C stabilization could be the physical protection within macroaggregate structures thereby minimizing the impact of conversion
of forest to cacao AFS. 相似文献