摘要:

ABSTRACT. Ecological and economic sustainability in an agroforest management system centered around Cunninghamia lanceolata has emerged over the centuries through the application of indigenous knowledge by peasants in China. The research presented focuses on three family lineages residing in the high mountain valleys of northern Fujian Province. While one lineage with minimal experience with the system tends to maximize short-term economic return, another with more experience has foregone such returns to insure long-term ecological sustainability. The third lineage, with still greater experience, has modifled the system still further to insure long-term ecological sustainability as well as maximize long-term economic returns. The system's sustainability has been achieved through knowledge of local ecological processes derived through traditional (non-literate) means. This knowledge has demonstrable scientific validity in several cases, including soil chemistry, soil biology, community ecology, and silvics. These cases are presented, as are estimates of the long-lerm economic returns of each lineage-specifc version of the system of intercropping, locally referred to as the shamu jionzhong.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_01

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Tropical deforestation in the Asia-Pacific Region has accelerated in Lhe last decade, seriously depleting the forest resource base. Most forest loss results from agricultural clearing, but is generally preceded by forest degradation from destructive logging (Southeast Asia) or overuse of forest resources (South Asia). Tropical forests are highly variable, requiring a system of classification to guide management objectives; one such system is ecological life zone mapping. Forestry operations should reflect the need for both conservation and production. Most Asia-Pacific forests are managed on variations of a selection system. Logging damage is the most important forestry-sector threat to commercial forestry, reducing both future timber production and the availability of non-timber products. The short duration of logging concession agreements, nontransferability of concession contracts, and undervaluation of forest resources all contribute to forest "mining" practices. Alternative forest management methods exist: logging damage can be substantially reduced at little or no additional cost; small-scale mobile sawmills can increase local incomes while reducing the need for skidding; and Assisted Natural Regeneration can facilitate the reforestation of denuded lands. The best hope for sustainable use of forest resources lies with those who must live with the consequences of forest mismanagement. Local involvement in foresy planning, implementation and enforcement is essential. Successful forest management projects depend on the judgement of field-based personnel familiar with the forests, cultures and institutions of each country, working in cooperation with local forestry experts and forest-dependent people.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_02

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The computer model ROTATION was developed to calculate and compare optimal rotation ages for even-aged forest stands according to mean annual increment, money yield table, forest rent, land expectation value, present net worth, internal rate of return, and financial maturity criteria. The program was written in Microsoft QuickBasic and h e input variables consist of volume yield data, stumpage price, land cost, stand establishment cost, stand management cost, and the rate of interest. Results are displayed in tabular format and values indicating the optimal rotation age based on each of the seven criteria are presented. A representative example is included which incorporates normal yield data for ponderosa pine (Pinus oonderosa Doual. ex Laws.) and commercial timber management revenues and expenditures approximating those currently countered in the Sierra Nevada and southern Cascades, USA. Potential users of ROTATION include forest managers and natural resource educators.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_03

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper reviews literature dealing with the measurement of oleoresin exudation pressure and the flow of resin from pine resin duct systems, with special reference to assessing tree resistance to bark beetle attack. The adequacy of a modification of Poiseuille's equation to predict resin flow is questioned, and resin pressure is judged to be an inadequate substitute for direct measurement of resin flow and estimation of tree resistance to bark beetle attack. Although direct measurement of resin flow is considered to be a superior method of eshating the relative resistance of trees to attack, it probably is not a totally satisfactory method for estimating resin flow, i.e., resistance to attack, associated with the progressive wounding done by bark beetles in their attempts to establish egg galleries. Multidisciplinary, integrated studies are needed to improve understanding of tree-bark beetle interactions.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_04

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Ever-wet forests of SW Sri Lanka are biodiversity hot spots with a wealth of potentially useful and currently used species. Traditional peoples surrounding these forests depend on them for a variety of focds, medicinals and the like as well as for timber. Some of these forests are being preserved as storehouses of diversity that include rare endemics and wild relatives of useful plants. Other natural forests and plantations must be managed for multiple uses including timber and non-timber products used by the forest dependent villagers. Understanding the ecological, social and economic interdependence of forests and rural communities is vital for the future forestry sector development in Sri Lanka. As many of the plants used locally are characteristic of early stages of gap regeneration, timber and non-timber products are compatible uses, given sufficiently judicious management. Anthropological and biological research is now in progress to plan for multiple use management of Sri Lankan ever-wet forests.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_05

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Aboveground-tree biomass and nutrient content (nitrogen, phosphorus, calcium, magnesium and potassium) were measured in 4-year-old stands of four indigenous tree species: Stryphnodendron microstachyum Poepp. et Endl. (ex S. excelsum Harms), Vochysia guatemalensis Donn. Smith (ex V. hondurensis Sprague), Vochysia ferruginea Mart and Hyeronima alchorneoides (0), growing on infertile soils in an experimental plantation in the Atlantic humid lowlands of Costa Rica. Biomass and nutrient content among the species, and among aboveground tree parts, forest-floor litter and understory vegetation were compared, as key factors that can be manipulated with different effects on site nutrient conservation. Biomass and stemwood annual increments of the four species were similar to those reported for other tropical tree plantations in the humid tropics. S. microstachyum had the highest accumulation of N in stem, branch and total aboveground tree biomass. V. guatemalensis had the highest accumulation of Ca and Mg in the biomass, while H. alchorneoides had the highest stem K and P. In spite of heir relatively lower N tissue collcentrations. V. ferruginea and H. alchorneoides showed a high potential for N recycling due to its more even distribution in stems, branches and leaves. Nument accumulation by the understory in S. microstachywn and H. alchorneoides plots was 0.8-7.746 of aboveground see biomass numents. The forest floor litter repsented a major compartment for nutrient accumulation and recycling under the four species, especially for N, Ca, Mg and P.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_06

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Secondary forests comprise either woody perennials and shrubs that establish in deforested lands (fallows or "barbecho") or degraded forests following over exploitation. fire, or overgrazing. Both vegetation exhibit rich, diversified, environrnent-protecting biomass. Either natural regeneration or preparation with silvicultural treatment and without further disturbance, they may eventually recover to their original condition in terms of bioecological forest structures. These forests derive their importance from the fact that they represent most of the forest resources on the surface of our planet. Primary forest covers only small areas and are decreasing at a rate between 0.5 to 1.15% a year. This paper describes various kinds of secondary forests, particularly those in Argentina (called "renovales," "fachinales," "capueras," and "bosques de rehaches") which include other vegetation types that may or may not be secondary (such as "vinalares," "churcales," "espinillares," and "chailares"). Silviculturally, all these kinds of forests, are treated with similar improvement (or conservation) techniques to maintain their stability, timber production, and environmental protection. These techniques include closings, liberations, refinements, thinnings, and enrichment plantings in the understory. Experience from research and industry in Argentina are presented herein. Proposals are made for the promotion of these forests such as research programs necessary to implement the institutional policies these forests require.

ISSN:1054-9811    

DOI:10.1300/J091v01n04_07

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor