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141.
Hemlock Woolly Adelgid (Adelges tsugae) is spreading across forests in eastern North America, causing mortality of eastern hemlock (Tsuga canadensis [L.] Carr.) and Carolina hemlock (Tsuga caroliniana Engelm.). The loss of hemlock from riparian forests in Great Smoky Mountains National Park (GSMNP) may result in significant
physical, chemical, and biological alterations to stream environments. To assess the influence of riparian hemlock stands
on stream conditions and estimate possible impacts from hemlock loss in GSMNP, we paired hardwood- and hemlock-dominated streams
to examine differences in water temperature, nitrate concentrations, pH, discharge, and available photosynthetic light. We
used a Geographic Information System (GIS) to identify stream pairs that were similar in topography, geology, land use, and
disturbance history in order to isolate forest type as a variable. Differences between hemlock- and hardwood-dominated streams
could not be explained by dominant forest type alone as forest type yields no consistent signal on measured conditions of
headwater streams in GSMNP. The variability in the results indicate that other landscape variables, such as the influence
of understory Rhododendron species, may exert more control on stream conditions than canopy composition. The results of this study suggest that the
replacement of hemlock overstory with hardwood species will have minimal impact on long-term stream conditions, however disturbance
during the transition is likely to have significant impacts. Management of riparian forests undergoing hemlock decline should,
therefore, focus on facilitating a faster transition to hardwood-dominated stands to minimize long-term effects on water quality. 相似文献
142.
本文对某工业园区的综合废水处理工艺开展了连续两年的运行调查,进行了其工艺完善及提标改造的技术探讨。研究表明,改造前该污水处理装置的出水COD、BOD5、总磷、SS均能达到排放标准,而唯独出水氨氮处理效果差,难以达到一级排放标准要求。通过增设预处理水解装置、生物氧化装置导流墙容积比改进、生物塘深度处理工艺完善后,能够保证出水氨氮的处理效果且能达到一级A排放标准。 相似文献
143.
A study of 13 small (less than 7.5 km2) watersheds on Mt. Desert Island, Maine, was conducted from January 1999 to September 2000 to determine nutrient export delivery
to coastal waters around the island, and to determine whether a series of wildfires in 1947 have affected nutrient export
in burned watersheds. Nutrient export (nitrate–nitrogen, total nitrogen, total phosphorus) was determined for each watershed
during the study period, and was normalized by watershed area. The yield of nitrate–nitrogen (N) ranged from 10 to 140 kg/km2/year. Total N yield ranged from 42 to 250 kg/km2/year. Total phosphorus (P) yield ranged from 1.4 to 7.9 kg/km2/year. Watersheds entirely within Acadia National Park (lacking human land-based nutrient sources) exported significantly
less total N and total P than watersheds that were partly or entirely outside the park boundary. Nitrate–N export was not
significantly different in these two groups of watersheds, perhaps because atmospheric deposition is a dominant source of
nitrate in the study area. No relation was observed between burn history and nutrient export. Any effect of burn history may
be masked by other landscape-level factors related to nutrient export. 相似文献
144.
Acadia National Park was one of the 14 sites included in the Park Research and Intensive Monitoring of Ecosystems network
(PRIMENet). For eight years the EPA monitored ultraviolet (UV) radiation at this site, with the National Park Service (NPS)
sponsoring a total climate and air monitoring station. Under the auspices of PRIMENet, research projects were initiated that
investigated the effects of UV on amphibians, determined watershed mass balances, and developed a model of deposition along
an elevational gradient. The monitoring data and research results have been used by park management to protect vegetation
and water resources from ozone and deposition. These data are now being used to develop a “vital signs” monitoring program
under the NPS’ Inventory and Monitoring Program. These data sets have been used in regional, national and international programs
to protect human health and resources from air pollution. Public outreach has been accomplished through web site resources
and via the Schoodic Education and Research Center. 相似文献
145.
Kahl JS Nelson SJ Fernandez I Haines T Norton S Wiersma GB Jacobson G Amirbahman A Johnson K Schauffler M Rustad L Tonnessen K Lent R Bank M Elvir J Eckhoff J Caron H Ruck P Parker J Campbell J Manski D Breen R Sheehan K Grygo A 《Environmental monitoring and assessment》2007,126(1-3):9-25
This paper is an overview of this special issue devoted to watershed research in Acadia National Park (Acadia NP). The papers
address components of an integrated research program on two upland watersheds at Acadia NP, USA (44° 20′ N latitude; 68° 15′
E longitude). These watersheds were instrumented in 1998 to provide a long-term foundation for regional ecological and watershed
research. The research was initiated as part of EPA/NPS PRIMENet (Park Research and Intensive Monitoring of Ecosystems Network),
a system of UV-monitoring stations and long-term watershed research sites located in US national parks. The initial goals
at Acadia NP were to address research questions about mercury, acid rain, and nitrogen saturation developed from prior research.
The project design was based on natural differences in forests and soils induced by an intense wildfire in one watershed in
1947. There is no evidence of fire in the reference watershed for several hundred years. We are testing hypotheses about controls
on surface water chemistry, and bioavailability of contaminants in the contrasting watersheds. The unburned 47-ha Hadlock
Brook watershed is 70% spruce-fir mature conifer forest. In contrast, burned 32-ha Cadillac Brook watershed, 4 km northeast
of the Hadlock watershed, is 20% regenerating mixed northern hardwoods and 60% shrub/rocky balds. Differences in atmospheric
deposition are controlled primarily by forest stand composition and age. The watersheds are gauged and have water chemistry
stations at 122 m (Cadillac) and 137 m (Hadlock); watershed maximum elevations are 468 and 380 m, respectively. The stream
water chemistry patterns reflect, in part, the legacy of the intense fire, which, in turn, controls differences in forest
vegetation and soil characteristics. These factors result in higher nitrogen and mercury flux from the unburned watershed,
reflecting differences in atmospheric deposition, contrasting ecosystem pools of nitrogen and mercury, and inferred differences
in internal cycling and bioavailabilty. 相似文献
146.
Schauffler M Nelson SJ Kahl JS Jacobson GL Haines TA Patterson WA Johnson KB 《Environmental monitoring and assessment》2007,126(1-3):39-53
Paleoecological reconstructions of forest stand histories for two upland watersheds at Acadia National Park in Maine were
completed to support related watershed chemistry studies. The project hypothesis was that forest type and fire history influence
long-term cycling and storage of atmospheric mercury and nitrogen within watersheds. The reconstructions document differences
in major vegetation composition and disturbance between the burned and unburned watersheds during the past several centuries.
Pollen and charcoal stratigraphies from organic sediment accumulations in forested wet depressions indicate that the present
experimental design of contrasting disturbance and forest histories has persisted during recent centuries. The unburned watershed
has been dominated by spruce (Picea rubens) and fir (Abies balsamea) for 500 years or more and has not recently burned or been substantially cleared. The burned watershed is dominated by a
heterogeneous forest of patchy hardwood, mixed wood, and softwood stands. A large portion of this watershed burned severely
in 1947 and probably more than once in the 1800s, and has supported heterogeneous successional forests for 200 years or longer.
Overall, these results support the underlying premise that the experimental design of this watershed research can be used
to infer landscape controls on biogeochemical processes. 相似文献
147.
Catherine Marina Pickering 《Ambio》2010,39(1):70-77
Protected areas represent the major method for conserving biodiversity. However, visitor use can threaten their conservation
value. Based on a review of recent research, I have categorized factors that affect the severity of environmental impacts
of visitor use. These factors need to be considered or evaluated when assessing visitor use of sites in protected areas. They
are: (i) the conservation value of the site, (ii) its resistance to use, (iii) its recovery from use, (iv) its susceptibility
to erosion, (v) the severity of direct impacts associated with specific activities, (vi) the severity of indirect impacts,
(vii) the amount of use, (viii) the social and (ix) ecological dimensions to the timing of use, and (x) the total area affected.
Although the factors may not be of equal importance or necessarily assessed on an equal scale, they allow people to make more
informed assessments of potential impacts, assist in identifying where monitoring may be required, and indicate where additional
site- or activity-specific research may be appropriate. 相似文献
148.
民族村寨游客的旅游体验质量研究——以西双版纳傣族园为例 总被引:1,自引:0,他引:1
目前国内对旅游体验和体验旅游的研究大多停留在理论研究层面。针对这一情况,以西双版纳傣族园游客为对象进行了实地问卷调查,采用社会统计学基本原理探索性地对游客的旅游体验质量进行了定量评价。结果表明,加强民族村寨的个性化体验旅游产品开发和民族文化旅游资源保护对少数民族地区旅游业的可持续发展具有重要的现实意义。 相似文献
149.
To address the dearth of literature on the relations between local residents in urban areas and nearby higher-order exurban
protected areas, this study examined the perceptions of Columbia (South Carolina) residents toward Congaree National Park.
Mail-out survey results from a random sample of 455 adult residents showed positive overall attitudes toward the park, although
this did not extend to a desire to personally volunteer in park activities. Cluster analysis on the basis of seven perceptual
statements produced three groups: “very enthusiastic park supporters” (VEPS), accounting for one fourth of the sample; “less
enthusiastic park supporters” (LEPS), accounting for approximately one half of the sample; and “ambivalents” (AMBS), accounting
for the rest. The AMBS tend to be younger than members of the other clusters and have higher income, but enthusiasm was more
clearly related to high levels of interaction and awareness relative to the park. Managerial implications of the study are
considered, including the need to encourage higher levels of park awareness and visitation, as well as more ecologically responsible
behavior, among residents of the greater Columbia urban area. 相似文献
150.
1 ThegeneralsituationoftheSouthDongtingLakeWetlandLocatedinthenorthofHunanProvinceandthesouthbankoftheYangtzeRivermiddlereaches ,theDongtingLakeisoneofthefivelargestfreshwaterlakesandofthesevenmostimportantlandscapesofinternationallyimportantwetlandsi… 相似文献