Restitution of forest property in post-communist Bulgaria

After ten years of post-communist transformation, the current Bulgarian Government has only recently initiated the task of wholesale reform of the communist-era structures extant within the forestry sector. This is an unavoidably complex process, involving the reorganisation of tenure over forest resources (restitution to pre-communist era owners), the privatisation and decentralisation of commercial and related activities in the woods, the redefinition of the role of the State in oversight, management and planning, and the development of a supportive institutional context for the growth of small and medium private enterprise throughout the forestry production process. This paper discusses the legal, institutional, economic and environmental implications of forest restitution. The author argues that the particular Bulgarian solution to the reform of forestry tenure structures, based on a mix of private and public ownership, arises out of the crucible of Bulgarian historical geography and the requirements of contemporary neoliberal models of transition. On the basis of the analysis, a number of important implications for Bulgarian, and indeed all post-communist forestry sectors, are raised for major related processes, such as the development of a robust private forestry sector, the limitation of the role of the State to conservation, management and oversight, and the reconfiguration of timber as a resource for local economic development.     

Determining size and dispersion of minimum viable populations for land management planning and species conservation

The concept of minimum populations of wildlife and plants has only recently been discussed in the literature. Population genetics has emerged as a basic underlying criterion for determining minimum population size. This paper presents a genetic framework and procedure for determining minimum viable population size and dispersion strategies in the context of multiple-use land management planning. A procedure is presented for determining minimum population size based on maintenance of genetic heterozygosity and reduction of inbreeding. A minimum effective population size (N _e ) of 50 breeding animals is taken from the literature as the minimum shortterm size to keep inbreeding below 1% per generation. Steps in the procedure adjustN _e to account for variance in progeny number, unequal sex ratios, overlapping generations, population fluctuations, and period of habitat/population constraint. The result is an approximate census number that falls within a range of effective population size of 50–500 individuals. This population range defines the time range of short- to long-term population fitness and evolutionary potential. The length of the term is a relative function of the species generation time. Two population dispersion strategies are proposed: core population and dispersed population.     

The hazard of forest fires in southern France

The annual hazard of fire in the forest, maquis and garrigue of southern France is related both to the fragile nature of the Mediterranean ecosystem and to man's activities. The Mediterranean vegetation is adapted to withstand the aridity of the summer months, but the combination of high temperatures, low precipitation, critical soil-moisture levels and occasional bouts of strong winds (mistral) desiccate the vegetation cover and create conditions in which outbreaks of forest fires are inevitable. Although the annual incidence and impact of forest fires are related to the occurrence of extreme weather conditions they are also exacerbated by depopulation of the remoter rural areas, the spread of urbanization and the growth of tourist facilities in the more accessible coastal zones, and above dl by man's carelessness. This article reviews the factors affecting the nature and severity of forest fires and discusses the attempts being made to prevent and control forest fires in the Mediterranean zone of southern France     

神山国家森林公园的森林旅游开发

森林旅游是生态旅游的重要形式之一,开展森林旅游已成为一种新的消费时尚,也是当今世界旅游的热点.介绍了神山国家森林公园优越的自然条件、丰富的森林旅游资源和人文旅游资源,分析了目前建设森林公园存在的问题,提出了发展森林旅游的建议.     

A Daily Time Series Analysis of StreamWater Phosphorus Concentrations Along an Urban to Forest Gradient

During a 1-year period, we sampled stream water total phosphorus (TP) concentrations daily and soluble reactive phosphorus (SRP) concentrations weekly in four Seattle area streams spanning a gradient of forested to urban-dominated land cover. The objective of this study was to develop time series models describing stream water phosphorus concentration dependence on seasonal variation in stream base flows, short-term flow fluctuations, antecedent flow conditions, and rainfall. Stream water SRP concentrations varied on average by ±18% or ±5.7 μg/L from one week to another, whereas TP varied ±48% or ±32.5 μg/L from one week to another. On average, SRP constituted about 47% of TP. Stream water SRP concentrations followed a simple sine-wave annual cycle with high concentrations during the low-flow summer period and low concentrations during the high-flow winter period in three of the four study sites. These trends are probably due to seasonal variation in the relative contributions of groundwater and subsurface flows to stream flow. In forested Issaquah Creek, SRP concentrations were relatively constant throughout the year except during the fall, when a major salmon spawning run occurred in the stream and SRP concentrations increased markedly. Stream water SRP concentrations were statistically unrelated to short-term flow fluctuations, antecedent flow conditions, or rainfall in each of the study streams. Stream water TP concentrations are highly variable and strongly influenced by short-term flow fluctuations. Each of the processes assessed had statistically significant correlations with TP concentrations, with seasonal base flow being the strongest, followed by antecedent flow conditions, short-term flow fluctuations, and rainfall. Times series models for each individual stream were able to predict ∼70% of the variability in the SRP annual cycle in three of the four streams (r² = 0.57–0.81), whereas individual TP models explained ∼50% of the annual cycle in all streams (r² = 0.39–0.59). Overall, time series models for SRP and TP dynamics explained 82% and 76% of the variability for these variables, respectively. Our results indicate that SRP, the most biologically available and therefore most important phosphorus fraction, has simpler and easier-to-predict seasonal and weekly dynamics.     

Computer-aided classification of forest cover types from small scale aerial photography

The US National Park Service must map forest cover types over extensive areas in order to fulfill its goal of maintaining or reconstructing presettlement vegetation within national parks and monuments. Furthermore, such cover type maps must be updated on a regular basis to document vegetation changes. Computer-aided classification of small scale aerial photography is a promising technique for generating forest cover type maps efficiently and inexpensively. In this study, seven cover types were classified with an overall accuracy of 62 percent from a reproduction of a 1120,000 color infrared transparency of a conifer-hardwood forest. The results were encouraging, given the degraded quality of the photograph and the fact that features were not centered, as well as the lack of information on lens vignetting characteristics to make corrections. Suggestions are made for resolving these problems in future research and applications. In addition, it is hypothesized that the overall accuracy is artificially low because the computer-aided classification more accurately portrayed the intermixing of cover types than the hand-drawn maps to which it was compared.     

石窟防震减灾与文物保护

针对石窟文物的特点,强调了防震减灾在石窟文物保护中的重要性．阐述了石窟的抗震防灾应从地震安全性评价、石窟地震稳定性分析、工程防护措施三个方面加以考虑,并就其中的一些关键问题进行了探讨．     

Preservation of organophosphorous pesticides in water samples

Abstract

Four techniques were studied for capacity to preserve sixteen organophosphorous pesticides in distilled water and in creek water. A technique using chloroform effectively preserved all sixteen pesticides for the three weeks of the study and refrigeration was effective for fourteen of the pesticides, but buffers of pH A and pH 7 appeared undependable as preservatives.     

Establishment of Markov successional model and its application for forest restoration reference in Southern China

Forest succession is the base of establishing restoration reference which plays an important role in forest restoration and restoration estimation. The study presented the establishment of a Markov successional model (MSM) and its application to restoration reference in lower subtropical forest in China. The compositions of successional system in MSM were divided into three species types: pioneering pine trees, heliophytic trees and mesophytic trees. The successional system was divided into three subsystems: early successional stage, mid-successional stage and late-successional stage. Based on the site survey on the changes in the species and their individuals in 25 years, the transition matrices in various subsystems were determined. The predicted results were used to establish the restoration reference of the vegetation restoration in lower subtropical China. According to the ecological restoration reference established in this study, it would take 150 years for the forest to change from pioneer to mature communities in the region. Successional change of tree composition was forecast by the model, and the scenario forecast by the model reflects the actual conditions observed through 52 years of long-term permanent site research. The restoration experience in the region matches the forecast results. The application of a restoration reference model indicates that forest restoration can be accelerated by taking measures which change forest structure. The above results imply that a restoration reference established on the rule of regional forest succession could be very useful not only in directing, but also in assessing and managing regional forest restoration. Previously, one “ideal reference ecosystem” was used as a restoration reference in all correlative studies. In this study, the restoration “process” was used as the restoration reference.     

Forest-user attitudes toward alternative fire management policies

The formulation and implementation of new fire policies in the national forests depend upon public acceptance. A national survey of organized groups of forest users indicates that, contrary to the concern of many forest managers, considerable support exists for flexible fire suppression policies. Forest users are also willing to accept the risk associated with the manager's use of prescribed fire. However, important intergroup differences do exist. Such variation is discussed in relation to a number of socioeconomic variables, general fire knowledge, specific knowledge about the effects of low-intensity fires, and risk preference levels.