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1.
Isla Victoria (Nahuel Huapi National Park, Argentina), a large island dominated by native Nothofagus and Austrocedrus forest, has old plantations of many introduced tree species, some of which are famed invaders of native ecosystems elsewhere.
There are also large populations of introduced deer and shrubs that may interact in a complex way with the introduced trees,
as well as a recently arrived population of wild boar. Long-standing concern that the introduced trees will invade and transform
native forest may be unwarranted, as there is little evidence of progressive invasion, even close to the plantations, despite
over 50 years of opportunity. Introduced and native shrubs allow scattered introduced trees to achieve substantial size in
abandoned pastures, but in almost all areas neither the trees nor the shrubs appear to be spreading beyond these sites. These
shrub communities may be stable rather than successional, but the technology for restoring them to native forest is uncertain
and probably currently impractical. Any attempt to remove the exotic tree seedlings and saplings from native forest would
probably create the very conditions that would favor colonization by exotic plants rather than native trees, while simply
clear-cutting the plantations would be unlikely to lead to regeneration of Nothofagus or Austrocedrus. The key to maintaining native forest is preventing catastrophic fire, as several introduced trees and shrubs would be favored
over native dominant trees in recolonization. Deer undoubtedly interact with both native and introduced trees and shrubs,
but their net effect on native forest is not yet clear, and specific management of deer beyond the current hunting by staff
is unwarranted, at least if preventing tree invasion is the goal. The steep terrain and shallow soil make the recently arrived
boar a grave threat to the native forest. Eradication is probably feasible and should be attempted quickly. 相似文献
2.
3.
The Gallatin Petrified Forest of Montana, USA, is a unique resource. The extensive area of the fossil forests, the numerous
petrified trees in upright positions, and the large number of vertical layers of “successive” forests are unparalleled in
the world. Collection by permit is permitted, but damage to the petrified forest by indiscriminate collection occurs. To assess
the impact, a comparative examination of replicate (over 13 yr) photography of selected specimens was undertaken. The amount
of change over time, the possible cause of change, and the relationship of the location of the specimen to that amount of
change were determined. It was found that although considerable loss continues, impacts prior to a 1973 collection policy
were most severe. There was more loss by natural erosion than by collection, but the collections are additive to the natural
changes. Size of petrified outcrops and the steepness of the slope on which they were found did correlate with the amount
of natural change occurring over time. Human-induced change was associated with the distance of the outcrops from the main
trailheads and the specimen size. This method provides a tool with which to monitor impacts and develop a future policy aimed
towards conservation of a unique resource in light of the need for appreciative recreation and some specimen collection. Recommended
changes in present management policy are provided. 相似文献
4.
《Resources Policy》1986,12(2):145-148
Bhutan is the only country in the Indian subcontinent which has been able to retain nearly three-quarters of its land under forests; this situation contrasts favourably with that in neighbouring countries where the Himalyan forests have been savagely degraded. The government of Bhutan is concerned to develop policies to preserve this valuable natural asset. 相似文献
5.
The study focuses on understorey-overstorey plant community dynamics in a dry tropical forest to facilitate appropriate management decisions. We compare community composition and species diversity of the understorey vegetation among five dry tropical forest sites in northern India. A total of 1500 quadrats distributed over 15 one-ha permanent plots in five sites differing in the degree of disturbance, were used to enumerate the understorey tree species and the results were compared with overstorey tree layer. The non-metric multidimensional scaling (NMS) ordination revealed that human disturbance intensity, as well as the overall disturbance regimes, and soil water holding capacity controlled the organisation of dry tropical forest understorey composition through effects on soil organic matter. The alpha-diversity and its components decreased with increasing human disturbance intensity, reflecting utilisation pressure and decreased soil fertility, as also revealed by the analysis of overstorey tree layer. There was a significant positive relationship between overstorey and understorey diversity. Results suggest that in the future, the existing understorey tree communities may replace the current dry tropical forest communities under prevailing environmental conditions. The study also asserts that the rate of species accumulation will be greater in more disturbed sites as well as at small spatial scale within each disturbance level. 相似文献
6.
Let us consider i = 1, 2,...n alternative forest plans to be evaluated according to j = 1, 2,...m indicators of sustainability. An expert or panel of experts suggests a set of targets or desirable levels of achievement for the m indicators of sustainability considered. Within this context, an important problem is to determine the system with a higher level of achievement with respect to the targets attached by the expert to the m indicators. A natural extension of this problem involves determining a ranking of the n systems considered. A general procedure based on discrete goal programming is proposed to address these problems. The methodology is applied in a case study of a Spanish forest. 相似文献
7.
Nathan L. Stephenson 《Environmental management》1987,11(1):1-5
Two recent studies using tree aggregations to analyze forest age-structure stability and past forest structure are flawed. A better understanding of aggregation dynamics is needed before aggregation analysis is used in forest management. 相似文献
8.
Skonhoft A 《Journal of environmental management》2005,76(2):167-175
This paper analyses how different management schemes influence the exploitation and economics of a wildlife population--the moose (Alces alces)--that is both a value (harvesting income) and a pest (forestry damage). Two regimes are explored; the unified management scheme where the wildlife manager aims to find harvesting quotas that maximise the overall benefit of the moose population, and the market solution where the landowners follow their narrow self-interests and maximise their private profit. Because the moose is partly a migratory species, these regimes will differ both with respect to harvesting income and browsing damage, and the landowners will experience different profit. The unified scheme is very similar to the actual Scandinavian management, while the market solution is closer to the management policy one finds in North America. In the first part of the paper it is shown how the harvesting quotas and browsing damage under these two regimes are influenced by dispersal as well as other ecological and economic factors. In the last part of the paper it is demonstrated that under the unified management regime the present practice of neglecting migration may lead to sub-optimally sized populations of migrating moose and an overall economic loss. It is also shown that neglecting migration leads to a substantial profit transfer among the landowners. The model is supported by a real life numerical example. 相似文献
9.
Michael Drescher Ajith H. Perera 《Journal of Environmental Planning and Management》2010,53(5):591-613
Forecasts of future resource states are central to resource management planning. Many simulation models and planning tools are used to produce such forecasts and apply knowledge of resource change dynamics as key input. Consistency among knowledge sources is therefore important to avoid knowledge ambiguity and uncertainty in resource forecasts and management plan outcomes. Using Ontario's boreal forest landscape as a case study, this paper examined two knowledge sources of forest resource change, practitioner expertise and research studies, commonly applied in plans and policies for large forest landscapes. The two knowledge sources were quantitatively compared by constructing networks of forest cover change for both sources and determining their agreement in structure and transition times. Some networks agreed well, indicating little knowledge ambiguity and comparatively low uncertainty if they were used to forecast forest landscapes. Other networks showed low agreement, thus indicating higher knowledge ambiguity and a dilemma of choice for forest landscape planners who may have to select from these knowledge sets. It is suggested that knowledge disagreements may be widespread in knowledge-driven management planning of many natural resource types and their causes similar. These disagreements signal areas of knowledge uncertainty, where resource planners must address resulting uncertainty of management outcomes and research should focus on improving resource change knowledge. 相似文献
10.
A pedagogic problem in forestry and landscape management is to visualize future landscape effects of forest growth and current management activities in the forest. This paper presents a method for forecasting digital image projections of forest landscape dynamics. Static nonlinear regression functions estimate the digital numbers in a Landsat Thematic Mapper image. Regressors used are forest stand variables. By estimating the future forest stand data, based on intermediate treatment and growth, future satellite digital images are created. In a case study example, the future landscape of a forest block in the province of Västernorrland, Sweden, is projected to demonstrate the application of this visualization technique. 相似文献
11.
Since the United Nations Conference on Environment and Development (UNCED) [1992, Agenda 21: programme of action for sustainable development. United Nations Conference on Environment and Development (UNCED), 3-14 June 1992. Rio de Janeiro, Brazil, 294pp.], the management of information has become central to the management of forest resources. In the cases of North America and Europe, similar issues have been challenging policy makers as they determine the information suitable for monitoring progress towards sustainable forest management (SFM). Using an 'online' survey, this research explored multiple stakeholder perspectives on monitoring and information reporting for SFM in different jurisdictions. The research was based on the premise that an analysis of the variation in stakeholder observations across a range of SFM 'issue areas' could provide valuable insight into the perceived need for SFM-related monitoring and information reporting in the regions of Europe, Canada and the USA. Despite the traditional limitations associated with exploratory survey research, the results indicate a demand for more information on SFM-related issues. The results also highlight the degree to which the perceptions of a sample of stakeholders can differ between Europe, USA and Canada. While these results cannot be generalized beyond the present study, they do suggest that further studies are needed to understand stakeholder perspectives on forestry-related monitoring and information reporting in different jurisdictions. 相似文献
12.
Evaluating sustainable forest management strategies with the Analytic Network Process in a Pressure-State-Response framework 总被引:1,自引:0,他引:1
Nowadays forestry faces a complex management situation; the understanding of sustainable forest management (SFM) has gone far beyond the original meaning of sustainable yield of timber. SFM strategies should fulfil ecological, economic and social functions without causing damage to other ecosystems. In this understanding, forest management actions cannot be seen as isolated or mono-causal. In this case study, indicators for SFM are arranged in a Pressure-State-Response (PSR) framework at forest management unit level. This framework links pressures on the environment caused by human activities with changes of environmental state (condition) parameters. Forest management also responds to these changes by instituting environmental and economic measures to reduce pressures and restore natural resources. The Analytic Network Process (ANP) is utilized to evaluate the performance of four management strategies with regard to the PSR framework on SFM. Priorities of indicators and alternatives are modelled with the ANP resulting from the interconnections to other indicators and their respective cumulative importance. The approach allows for more detailed information on the network of human influences and their impacts on forest ecosystems and goes beyond the limitations of flat-dimensioned indicator sets. 相似文献
13.
The potential of devolved conservation to empower people, reduce poverty and protect forest resources has yet to be realized in much of the developing world. This is particularly evident in the Philippines where the central state paradoxically recentralizes political power through devolution at the policy, program and project level in forest management. We investigate how centralized state power emanates through devolved networks to affect the success of local timber utilization involving community-based forest management (CBFM) on Mindanao Island, the southern Philippines. By examining broader shifts from centralized to devolved forest management, results suggest that centralized political power continues to control and adversely affect local uses of timber through CBFM. We discuss how in the process of state authorities recentralizing devolved rights and responsibility over timber management, community-based logging operations were threatened but sustained by members relying on community-based structures and their own capabilities. The conclusion asserts that broader state processes of devolving power over timber management remains constrained by political motives and interests and so largely fails to fulfill the objectives of community-based forest management. 相似文献
14.
This paper provides an overview of the emerging role of Aboriginal people in Sustainable Forest Management (SFM) in Canada over the past decade. The 1996 Royal Commission on Aboriginal Peoples (RCAP) provided guidance and recommendations for improving Aboriginal peoples' position in Canadian society, beginning with strengthening understanding and building relationships between Aboriginal and non-Aboriginal parties. This paper explores the extent to which advances in Aboriginal/non-Aboriginal relationships and Aboriginal forestry have been made as a result of RCAP's call for renewed relationships based on co-existence among nations. Such changes have begun to alter the context in which Aboriginal/non-Aboriginal relationships exist with respect to SFM. While governments themselves have generally not demonstrated the leadership called for by RCAP in taking up these challenges, industry and other partners are demonstrating some improvements. A degree of progress has been achieved in terms of lands and resources, particularly with co-management-type arrangements, but a fundamental re-structuring needed to reflect nation-to-nation relationships has not yet occurred. Other factors related to increasing Aboriginal participation in SFM, such as the recognition of Aboriginal and treaty rights, are also highlighted, along with suggestions for moving Aboriginal peoples' SFM agenda forward in the coming years. 相似文献
15.
Madhu Ramnath 《Natural resources forum》2001,25(3):245-256
This article enters the debate on shifting cultivation and tropical forests, and the role of the State forest departments in managing these regions. The article focuses on the adivasi (indigenous) people and their use of forests in the Bastar region of Madhya Pradesh in Central India. It examines the different landscapes, resulting from human interaction, in order to observe the vegetative changes and progressions in their characteristics; in particular, the author challenges the view that adivasi forest use has been detrimental to the ecology of the forest. A botanical comparison is made between three sites that allow us to note specific characteristics of a fallow, a secondary forest and a primary sal (Shorea robusta) forest. The wider aspects of the adivasi manner of forest use are also discussed.
A major portion of the Bastar region is legally under the authority of the Madhya Pradesh State Forest Department. However, the official policies and laws, pertaining to the conservation of forests and the generation of revenue, are often insensitive to the adivasi perceptions and use of the various vegetative zones within the forest. The effect of a standardised form of demarcation, coupled with the State legislation, has overlooked the adivasi people's needs and their ecologically sound way of relating to the forest. The paper concludes with a few recommendations. 相似文献
A major portion of the Bastar region is legally under the authority of the Madhya Pradesh State Forest Department. However, the official policies and laws, pertaining to the conservation of forests and the generation of revenue, are often insensitive to the adivasi perceptions and use of the various vegetative zones within the forest. The effect of a standardised form of demarcation, coupled with the State legislation, has overlooked the adivasi people's needs and their ecologically sound way of relating to the forest. The paper concludes with a few recommendations. 相似文献
16.
A GIS model predicting the spatial distribution of terrestrial salamander abundance based on topography and forest age was developed using parameters derived from the literature. The model was tested by sampling salamander abundance across the full range of site conditions used in the model. A regression of the predictions of our GIS model against these sample data showed that the model has a modest but significant ability to predict both salamander abundance and mass per unit area. The model was used to assess the impacts of alternative management plans for the Hoosier National Forest (Indiana, USA) on salamanders. These plans differed in the spatial delineation of management areas where timber harvest was permitted, and the intensity of timber harvest within those management areas. The spatial pattern of forest openings produced by alternative forest management scenarios based on these plans was projected over 150 years using a timber-harvest simulator (HARVEST). We generated a predictive map of salamander abundance for each scenario over time, and summarized each map by calculating mean salamander abundance and the mean colonization distance (average distance from map cells with low predicted abundance to those with relatively high abundance). Projected salamander abundance was affected more by harvest rate (area harvested each decade) than by the management area boundaries. The alternatives had a varying effect on the mean distance salamanders would have to travel to colonize regenerating stands. Our GIS modeling approach is an example of a spatial analytical tool that could help resource management planners to evaluate the potential ecological impact of management alternatives. 相似文献
17.
Water quality effects of clearcut harvesting and forest fertilization with best management practices
Nine small (2.5 ha) and four large (70-135 ha) watersheds were instrumented in 1999 to evaluate the effects of silvicultural practices with application of best management practices (BMPs) on stream water quality in East Texas, USA. Two management regimes were implemented in 2002: (i) conventional, with clearcutting, herbicide site preparation, and BMPs and (ii) intensive, which added subsoiling, aerial broadcast fertilization, and an additional herbicide application. Watershed effects were compared with results from a study on the same small watersheds in 1981, in which two combinations of harvesting and mechanical site preparation without BMPs or fertilization were evaluated. Clearcutting with conventional site preparation resulted in increased nitrogen losses on the small watersheds by about 1 additional kg ha(-1) each of total Kjeldahl nitrogen (TKN) and nitrate-nitrogen (NO(3)-N) in 2003. First-year losses were not significantly increased on the large watershed with a conventional site preparation with BMPs. Fertilization resulted in increased runoff losses in 2003 on the intensive small watersheds by an additional 0.77, 2.33, and 0.36 kg ha(-1) for NO(3)-N, TKN, and total phosphorus, respectively. Total loss rates of ammonia nitrogen (NH(4)-N) and NO(3)-N were low overall and accounted for only approximately 7% of the applied N. Mean loss rates from treated watersheds were much lower than rainfall inputs of about 5 kg ha(-1) TKN and NO(3)-N in 2003. Aerial fertilization of the 5-yr-old stand on another large watershed did not increase nutrient losses. Intensive silvicultural practices with BMPs did not significantly impair surface water quality with N and P. 相似文献
18.
Francesca Ferranti Pau Vericat Jessica de Koning 《Journal of Environmental Planning and Management》2017,60(12):2085-2102
This study analyzed discourses influencing the meaning of Sustainable Forest Management in Catalonia (Spain) and the effects of the European Natura 2000 policy on these discourses. It focused on the Montseny area and on the Administration and Practitioner stakeholder groups. Based on literature review and interviews, we found six discourses influencing the meanings of Sustainable Forest Management. Two of these discourses underwent changes due to the effects of Natura 2000 implementation while the others did not, showing the substantial role played by local elements and actors in shaping the discursive framework of Sustainable Forest Management. Based on empirical findings, the study provided conclusions valid at European level: (1) implementing Natura 2000 does not mean revolutionizing local nature conservation systems, but rather adapting them to European requirements; (2) in order to increase local policy impact, the implementation of European environmental policies needs to be backed up by economic compensation of local actors. 相似文献
19.
Leticia Pafundi M. Florencia Urretavizcaya Guillermo E. Defossé 《Environmental management》2014,54(6):1412-1420
This study was aimed at determining, under field conditions, early interactions between planted cypress seedlings and their associated shrubs in a mesic area of Andean Patagonia and, in a nursery, the effects of increasing light availability on cypress performance when soil water was not a limiting factor. The field experiment was performed in a former cypress–coihue mixed forest (42°02′S, 71°33′W), which was replaced in the 1970s by a plantation of radiata pine. In 2005, 800 cypress seedlings were planted under maqui shrubs in a clear-cut area of the pine stand. In 2007, two treatments were set: no-competition treatment ([NCT] i.e., the surrounding aboveground biomass was removed) and competition treatment ([CT] i.e., without disturbance). The nursery experiment (42°55′S, 71°21′W) consisted of two groups: “shade” (grown under shade cloth) and “sun” (grown at full sun) cypress seedlings. After one growing season, seedling survival and stem growth (in height and diameter) were determined at both sites. Furthermore, the growth rate of leaves, stems, and roots was determined in the nursery. In the field experiment, height growth and survival in NCT were significantly greater than in CT, and a competition process occurred between cypress and surrounding shrubs. In the nursery, sun plants grew more in diameter and increased root weight more than shade plants. Results also showed that in mesic areas of Patagonia, decreasing competition and increasing light levels produced stouter seedlings better adapted to support harsh environmental conditions. Therefore, the removal of protecting shrubs could be a good management practice to improve seedling establishment. 相似文献
20.
We followed selection guidelines commonly used by management agencies to select mountain quail (Oreortyx pictus) as an indicator species for an ecological guild of birds. We then evaluated the ability of mountain quail to indicate the presence of other species from the guild and to index the quality of the habitat for other species. The ability of quail to indicate the presence of species from the ecological guild varied widely within and among vegetation types. Species compositions of the ecological guild were more consistent in comparisons of sites within vegetation types than they were in comparisons of sites between vegetation types. Mountain quail habitat was significantly different from the habitats of sympatric species from the guild for 14 of 15 multivariate contrasts. We suggest that managers use indicator species with caution. If indicators are used, they should be applied to guilds composed of species that closely share ecological affinities. The habitat of the indicator species should overlap extensively with those of all other guild members. The use of indicators should be restricted to very similar sites within the same general vegetation type. 相似文献