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Reconciling salvage logging of boreal forests with a tural-disturbance management model.

In North American boreal forests, wildfire is the dominant agent of natural disturbance. A natural-disturbance model has therefore been promoted as an ecologically based approach to forest harvesting in these systems. Given accelerating resource demands, fire competes with harvest for timber and there is increasing pressure to salvage naturally burned areas. This creates a management paradox: simultaneous promotion of natural disturbance as a guide to sustainability while salvaging forests that have been naturally disturbed. The major drivers of postfire salvage in Canadian boreal forests are societal perceptions, overallocation of forest resources, and economic and policy incentives, and postfire salvage compromisesforest sustainability by diminishing the role of fire as a critical, natural process. These factors might be reconciled through consideration of fire in resource allocations and application of active adaptive management. We provide novel treatment of the role of burn severity in mediating biotic response by examining its influence on the amount, type, and distribution of live, postfire residual material, and we highlight the role of fire in shaping spatial and temporal patterns in forest biodiversity. Maintenance of natural postfire forests is a critical component of an ecosystem-based approach to forest management in boreal systems. Nevertheless, presentpracticesfocus heavily on expediting removal of timber from burned forests, despite increasing evidence that postfire communities differ markedly from postharvest systems, and there is a mismatch between emerging management models and past management practices. Policies that recognize the critical role of fire in these systems and facilitate enhanced understanding of natural system dynamics in support of development of sustainable management practices are urgently needed.

Biodiversity↗

China's forest policy for the 21st century.

A half-century policy of forest exploitation and monoculture in China has led to disastrous consequences, including degradation of forests and landscapes, loss of biodiversity, unacceptable levels of soil erosion, and catastrophic flooding. A new forest policy had been adopted in China called the Natural Forest conservation Program (NFCP), which emphasizes expansion of natural forests and increasing the productivity of forest plantations. Through locally focused management strategies, biodiversity and forest resources will be sustained, and downstream regions will be better protected from flooding. This new policy is being implemented with a new combination of policy tools, including technical training and education, land management planning, mandatory conversion of marginal farmlands to forest, resettlement and retaining of forest dwellers, share in private ownership, and expanded research. These policy tools may have wider relevance for other countries, particularly developing countries.

Agriculture↗

Forest age influences oak insect herbivore community structure, richness, and density.

Plant succession is one of many factors that may affect the composition and structure of herbivorous insect communities. However, few studies have examined the effect of forest age on the diversity and abundance of insect communities. If forest age influences insect diversity, then the schedule of timber harvest rotation may have consequent effects on biodiversity. The insect herbivore community on Quercus alba (white oak) in the Missouri Ozarks was sampled in a chronoseries, from recently harvested (2 yr) to old-growth (approximately 313 yr) forests. A total of nine sites and 39 stands within those sites were sampled in May and August 2003. Unique communities of plants and insects were found in the oldest forests (122-313 yr). Density and species richness of herbivores were positively correlated with increasing forest age in August but not in May. August insect density was negatively correlated with heat load index; in addition, insect density and richness increased over the chronoseries, but not on the sunniest slopes. Forest structural diversity (number of size classes) was positively correlated with forest age, but woody plant species richness was not. In sum, richness, density, and community structure of white oak insect herbivores are influenced by variation in forest age, forest structure, relative abundance of plant species, and abiotic conditions. These results suggest that time between harvests of large, long-lived, tree species such as white oak should be longer than current practice in order to maintain insect community diversity.

Animals↗

Lead reduction and redistribution in the forest floor in New Hampshire northern hardwoods.

Because of the affinity of organic matter for lead, atmospheric loadings of this pollutant have been strongly retained in the forest floor. With the regulation of Pb emissions, loadings have decreased. We measured changes in Pb in forest floor horizons at a variety of northern hardwood sites in New Hampshire from the late 1970s to the 1990s. In all seven of the sites in which horizons were distinguished within the forest floor, Pb was found to be declining in the upper (Oie) horizon, but not in the underlying Oa and A horizons. At the Hubbard Brook Experimental Forest (HBEF), this loss from the Oie resulted in a 36% loss of Pb from the forest floor as a whole between 1976 and 1997 (p < 0.001). In contrast, in six stands in the Bartlett Experimental Forest (BEF), losses of Pb averaging >50% from the Oi and Oe horizons (p = 0.01) between 1979 and 1994 were compensated by gains in the Oa and A horizons. Similarly, at seven additional stands in the White Mountain National Forest, changes in the forest floor as a whole from 1980 to 1995 were not statistically significant (redistribution within the forest floor was not evaluated at these sites). Lead concentrations were highest in the Oe or Oie in the 1970s, but were highest in the Oa horizon in the 1990s. There was no significant pattern of Pb loss or retention as a function of stand age across all the sites.

Environmental Monitoring↗

[Species structure of natural secondary forest in the Wudaohe farm].

The analysis of soil thickness and slope gradient in natural secondary forest of the Wudaohe forest farm showed that the area of the secondary forest whose soil thickness was lower than 30 cm and slope gradient was higher than 25 degrees was 2390.1 hm2, covering 83.5% of its total area, while the area with soil thickness of higher than or equal to 30 cm and slope gradient of lower than or equal to 25 degrees was only 474.2 hm2, covering 16.5% of the total. It is suggested that the secondary forest is ecologically fragile, and this forest farm should develop a mulriple forest including waterhead-protection forest, lumber stand and economic forest. It was shown by analytic hierarchy process (AHP) that the suitable ratio of three forest types is 72.7%, 18.6%, 8.7%, respectively.

Soil↗

[Early diagnosis of low-value forest: an approach of ecological factors].

The management and improvement of low-value forests is an important issue of forestry in China. This paper put forward a new thought of early diagnosis for low-value forest. By applying this method, the forest growth trend before the explosion of the state of low-value forest was diagnosed according to the formation rule of low-value forest, and so, managers could adopt corresponding management measures in time. Taking a case study of Chinese pine plantations in western Liaoning Province, the early diagnosis of low-value forest was studied, and set up early diagnosis techniques of ecological factor approach based on single-factor experiment and discriminant analysis: 1) following discriminant indices were selected: soil thickness (X1), organic matter (X2), soil nitrogen content (X3), soil water content (X4), and soil microbic quantity (X5); 2) discriminant function could be expressed as: Y = 1.596X1 - 0.51X2 - 3.196X3 + 1.622X4 + 1.898X5:3) early diagnosis of low-value forest was carried out by discriminant function and the value of each discriminant index. For early diagnosis of low-value forest, this paper is a pilot study. It is suggested that the forming mechanism of low-value forest and their related study should be strengthened.

China↗

[Method for measurement of optical stratification porosity (OSP) and its application in studies of management for secondary forests].

Secondary forest is the main body of forests in China, and hence, its management plays a very important role in the projects of natural forest conservation and ecological environment construction in this country. The structure, especially the vertical stratification structure of secondary forest is one of the key factors in the management of secondary forest, and can be considered as the base of its management. Based on previous studies, the concept of stratification porosity was introduced, and the optical stratification porosity (OSP), which is the two dimensional alternative measurement of stratification porosity, could be used to represent the vertical stratification structure of secondary forest. The method using hemispherical photographic silhouette (photographic silhouette taken with fisheye lens) to estimate the OSP of a forest stand was also introduced. In addition, the possible applications of OSP in studies on the structure and restoration ecology of secondary forest, and the theory and techniques for the management of secondary forest were also given in this paper.

Conservation of Natural Resources↗

[On the causes of mite pest outbreaks in mono- and poly-cultured moso bamboo forests].

In this paper, the damage of phytophagous mites Schizotetranychus nanjingensis Ma & Yuan, Aponychus corpuzae Rimando and Aculus bambusae Kuang to moso bamboo (Phyllostaychs pubescens) was examined for ten pairs of mono- and poly-cultured forests at six locations in Fujian, China. The results showed that the mite damage in mono-cultured forests (35%) was twice as high as that in poly-cultured forests (17.5% < the injury level of 20%), and the difference was significant by t-test. The total pest mites in the mono-cultured forests at six locations in Fujian were 289.29% as high as those in the poly-cultured stands. Typhlodromus bambusae, a nature enemy in the poly-cultured forests at five locations in Fujian, was 262.5% as high as that in the mono-cultured forests. The proportion of pest mite and nature enemy in the mono-cultured forests was 1:118, but was 1:13 in the poly-cultured forests. The change of bamboo cultivation (mono-culture, crowding of bamboo plants, and removal of underfloor plants) might be the major cause of mite pest outbreaks in moso bamboo forests.

Animals↗

[Forest Inventory Data (FID)-based biomass models and their prospects].

Forest Inventory Data (FID)-based biomass models are important methods in assessing forest biomass at landscape, regional, and national scales, and play an important role in studying terrestrial carbon budget and global changes. In this paper, Forest Inventory Data were reviewed, FID-based models were summarized, and shortages of FID-based models were analyzed. Based on these analyses, the future tasks were pointed out: 1) Comprehensive effect of forest biological factors and non-biological factors on forest biomass, especially on forest volume and age; 2) Identification of the relationships between total forest biomass and live wood biomass; 3) Development of remote sensing- and FID-based forest biomass models. These researches will provide new methods and theoretical bases for estimating forest biomass and carbon budget.

Biomass↗

[Effects of disturbances on plant species diversity of secondary forest in montane regions of eastern Liaoning Province].

According to the distance from forest stands to residential area and the first and second grade roads, as well as the canopy density and the percentage of damaged trees, this paper defined the disturbances, anthropogenic and natural, as low, medium and high levels. On the basis of this, the effects of different level disturbances on the plant species diversity of secondary forest in montane regions of eastern Liaoning Province were analyzed, and the differences between the effects of anthropogenic and natural disturbances were discussed. The results showed that without considering forest types, the overall plant species diversity of secondary forest under medium level anthropogenic disturbance was higher than that under low and high level anthropogenic disturbances, with the Simpson indexes being 0.96, 0.95 and 0.92, and Shannon-Wiener indexes being 3.77, 3.60 and 3.36, respectively. The diversities of shrub and herb layers were also the highest under medium level anthropogenic disturbance, while the highest diversity of arbor layer was appeared under the high level one. Among different forest types, there existed differences in the plant species diversity under anthropogenic disturbances, e. g. , the diversity under medium level anthropogenic disturbance was the lowest in hard broad-leaved forests, but the highest in other forest types. In all test forest types, no consistent tendency was observed in the changes of three layers' diversities with anthropogenic disturbance levels, but the diversities of shrub and herb layers were greatly affected by the disturbances. After 3 years of snow/wind damage, there was no distinct difference in the diversities among the birch forests under low, medium and high level natural disturbances, with the Simpson indexes being 0.91, 0.91 and 0.92, and the Shannon-Wiener indexes being 2.30, 2.93 and 2.89, respectively. The diversities of arbor and shrub layers were both increased with the enhancement of natural disturbances, but there was no great difference in the diversity of herb layer among the three levels of natural disturbances. At present, anthropogenic disturbance mostly occurred in understory, while snow/wind damage occurred in canopy. Such dissimilarity could make the effects of environmental factors on plant species diversity differed greatly.

Biodiversity↗

Regulations of the Forest Law, 29 June 1988.

These Regulations set forth the administration and duties of various government departments under the Mexican Forest Law. They provide that the National Forest Administration is, among other things, to promote operations designed for the conservation, protection, and restoration of forest resources, especially with respect to disasters of any kind that affect forests, such as pestilence, fires, disease, floods, and acid rain, as well as other destructive and contaminating elements. Further provisions of the Regulations describe efforts to aid reforestation and silviculture to be undertaken by the Secretariat and activities with respect to use permits and forest management. In its efforts to aid reforestation, the Secretariat is to establish nurseries, give assistance to local bodies to establish nurseries, and support reforestation programs financially. Regulations of the General Law on Ecological Equilibrium and Environmental Protection with Respect to Environmental Impact of 6 June 1988 contain provisions requiring the Secretariat of Urban Development and Ecology to formulate general rules on the environmental impact involved in the use of forests. These rules are to set forth measures on prevention, improvement, preservation, restoration, and control. The Secretariat is also to issue ecological protection restrictions on the use of forest resources, which are to be relied on in the evaluation of proposed forest use projects. The Regulations also set forth procedures to be followed in examining use permit applications and information that must be included in such applications. See Diario Oficial, Vol. 417, No. 5, 7 June 1988, p. 28.

Americas↗

Temporal and Spatial Distribution of the nifH Gene of N(2) Fixing Bacteria in Forests and Clearcuts in Western Oregon.

Decomposition of plant litter is a primary mechanism of nutrient recycling and redistribution in most terrestrial ecosystems. Previously we demonstrated by a nested PCR protocol that 20 distinctive nifH (the gene encoding nitrogenase reductase) HaeIII restriction fragment length polymorphism (RFLP) patterns were derived from bulk DNA associated with samples of plant litter and soil collected at one Douglas Fir (DF) forest [33]. Five of the nifH DNA patterns (II-VI) were dominant types in DF litter with characteristic fragments of 237-303 bp length, whereas samples from soil contained primarily seven other patterns 131-188 bp length (IX-XV). Here we report that the 237-303 bp fragments characteristic for forest litter could generally not be detected in plant litter or soil samples collected in clearcuts that adjoin the forest sites. The same fragments (237-303 bp) were also found in the litter at this DF forest site over 16 months and were consistently found in litter at 12 other DF forest or recent (<2 yrs) clearcut sites. However, trace to none of these fragments were detected in 6 clearcut (5-10 yrs) or different forest types (oak, alder) collected over a 200 km east-west direction in western Oregon, USA. Data suggest that the logging practice in DF forests that creates a clearcut removes a unique gene pool of nitrogen-fixing microorganisms. These organisms could potentially contribute more to nitrogen fixation in forest litter than litter from natural or invasive plants that grow in clearcuts [26]. </hea

Journal Article↗

GIS-based support tool system for decision-making regarding local forest protection: illustrations from Orissa, India.

A support tool system comprising risk and priority analyses was illustrated in a geographical information system environment and also tested with data from two forest protection areas for comparison of the system output. The system is recommended as a management monitoring tool for areas where village forest protection at a local level is taking place. The geographical area in the eastern part of India is subject to scarcity of forest resources and is representative in the context of widespread occurrence of local forest protection. Data used were topography, hectares protected, population census, distance to forest and other villages, degree of forest regeneration, presence of plantations, age of protection, surrounding forest resources, and population mix. Methods used were digitizing information for the systems' different layers, analyses of satellite information, field work, gathering of local information, and the application of five risk/priority analyses: erosion, ecological and institutional sustainability, conflict, and degree of dependency. Questions asked were how the different analyses should be interpreted and how the system could be kept updated. The results show that the system needs resource-demanding and field assistance to be kept dynamic. The system is also dependent on the interpretations of the analyses. The limits or levels of assistance for forest management depend on the resources available. The system illustrates how a tool can be utilized for decisions regarding input of resources. It can further be very useful in defining and comparing different areas in order to detect areas in need of assistance and the type of help needed.

Conservation of Natural Resources↗

Effects of changing forest and impervious land covers on discharge characteristics of watersheds.

Effects of changing patterns of forest and impervious land covers on hydrologic regimes of watersheds were evaluated for urban and rural areas of the lower Cedar River drainage near Seattle, Washington. Land cover characterizations were used in a spatially explicit hydrology model to assess effects of land covers on watershed hydrology during presettlement conditions ("full forest cover"), 1991 and 1998. For the presettlement to 1991 period, urban watersheds showed decreases in forest covers (range 63% to 83%) and increases in impervious surfaces (range 43% to 71%). Rural watersheds showed similar patterns but smaller changes, with forest covers decreasing (range 28% to 34%) and impervious surfaces increasing (range 8% to 15%). For the 1991 and 1998 period, changes in forest covers for urban and rural watershed were <24%, with losses in some watersheds and regeneration in others. Impervious surfaces continued to increase, but increases were larger in rural (range 38% to 60%) than in urban watersheds (range 4% to 27%). Flood-frequency curves indicated that discharge rates (m sec(-1)) for all watersheds were higher in 1991 and 1998 than historical and suggested that chances for floods increase because of changing land covers. The largest increases in discharge rates were in urban watersheds, with rates for 2-year, 10-year, and 25-year recurrence intervals being more than two times greater than the rate during historical conditions. Changes in flow regimes were indicated by presettlement discharge levels of less frequent recurrence intervals (10-year and 25-year) occurring in posturbanization times (1991 and 1998) during more frequent intervals (2-year and 10-year). Normalized flows (m yr(-1)) of watersheds for 2-year, 10-year, and 25-year recurrence intervals indicate how flow regimes in 1991 and 1998 can change as functions of different areas of land covers. During 1991 and 1998, abrupt increases in flows occurred when forest covers were low (range 17% to 37%) and impervious surfaces were >46%. In contrast, the lowest flows occurred when forest covers were most extensive (range 59% to 81%) and impervious surfaces were <23%. We conclude that our use of spatial characterizations of impervious surfaces and forested covers in a spatially explicit hydrology model provides a robust approach for revealing how variations in different types and spatial distributions of land covers can affect flood regimes and flows of different watersheds.

Cities↗

Indigenous systems of forest classification: understanding land use patterns and the role of NTFPs in shifting cultivators' subsistence economies.

This article discusses the system of classification of forest types used by the Pwo Karen in Thung Yai Naresuan Wildlife Sanctuary in western Thailand and the role of nontimber forest products (NTFPs), focusing on wild food plants, in Karen livelihoods. The article argues that the Pwo Karen have two methods of forest classification, closely related to their swidden farming practices. The first is used for forest land that has been, or can be, swiddened, and classifies forest types according to growth conditions. The second system is used for land that is not suitable for cultivation and looks at soil properties and slope. The article estimates the relative importance of each forest type in what concerns the collection of wild food plants. A total of 134 wild food plant species were recorded in December 2004. They account for some 80-90% of the amount of edible plants consumed by the Pwo Karen, and have a base value of Baht 11,505 per year, comparable to the cash incomes of many households. The article argues that the Pwo Karen reliance on NTFPs has influenced their land-use and forest management practices. However, by restricting the length of the fallow period, the Thai government has caused ecological changes that are challenging the ability of the Karen to remain subsistence oriented. By ignoring shifting cultivators' dependence on such products, the involvement of governments in forest management, especially through restrictions imposed on swidden farming practices, is likely to have a considerable impact on the livelihood strategies of these communities.

Agriculture↗

Perceptions of prescribed burning in a local forest community in Victoria, Australia.

The general perceptions of prescribed burning were elicited from forest users for an area that has been subject to this form of land management for at least 20 years. The largest group consisted of local residents living in and around the Wombat State Forest with two smaller groups of students from a nearby university campus and local professional land managers. A questionnaire was given to each participant in order to explore how the forest was used, to determine the level of knowledge of burning in the targeted forest and Victoria and the perception of the appearance, effectiveness of protection, and accessibility to the forest after prescribed burning. Generally all groups had similar responses with community members having stronger views on the effectiveness and practicalities of prescribed burning, whereas students were more neutral in their opinions. All participants claimed knowledge of prescribed burning activities within Victoria, but fewer had experience of planned fires in the Wombat State Forest. All groups agreed that areas that had not been recently burned had a better appearance than those that had, but this result may have included a range of value judgments. Land managers had a greater understanding of the ecological importance of season and timing of burning; however, some students and community members were equally knowledgeable. Prescribed burning did not impede access to the forest, nor did smoke from prescribed burns pose any great problem. The majority of the participants felt that the amount of prescribed burning done in the forest was adequate for engendering a feeling of protection to life and property, yet many were still suspicious of this management practice. These initial findings indicate several areas in which further research would be useful including the efficacy of education programs for community members and improved communication of burn plans by land managers.

Conservation of Natural Resources↗

Jamaica's disappearing forests: physical and human aspects.

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.

Agriculture↗

Simulating Spatial and Temporal Context of Forest Management Using Hypothetical Landscapes

/ Spatially explicit models that combine remote sensing with geographic information systems (GIS) offer great promise to land managers because they consider the arrangement of landscape elements in time and space. Their visual and geographic nature facilitate the comparison of alternative landscape designs. Among various activities associated with forest management, none cause greater concern than the impacts of timber harvesting on the composition, structure, and function of landscape ecosystems. A timber harvest allocation model (HARVEST) was used to simulate different intensities of timber harvest on 23,592-ha hypothetical landscapes with varying sizes of timber production areas and different initial stand age distributions. Our objectives were to: (1) determine the relative effects of the size of timber production areas, harvest intensity, method used to extract timber, and past timber harvest activity on the production of forest interior and edge; and (2) evaluate how past management (in the form of different initial stand age distributions) constrains future timber production options. Our simulations indicated that the total area of forest interior and the amount of forest edge were primarily influenced by the intensity of timber harvest and the size of openings created by harvest. The size of the largest block of interior forest was influenced most by the size of timber harvests, but the intensity of harvest was also significant, and the size of nontimber production areas was important when harvests were numerous and widely dispersed within timber management areas, as is often the case in managed forests. Stand age-class distributions produced by past harvest activity limited the amount of timber production primarily when group selection was used, but also limited clear-cutting when recent harvest levels were high.KEY WORDS: Simulation modeling; Timber harvest; Historical context; Spatial context; Landscape pattern; Forest interior; Forest edge

Journal Article↗