ISSN:1054-9811    

DOI:10.1300/J091v07n03_01

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This study pertains to the density-diameter (d-d) curves, diameter class distribution of dominant species and protective value of temperate forests between 2000 and 3300 m amsl in Pinder catchment of the Central Himalaya. The identified forests were mixed deciduous-evergreen, alder(Alnus nepalensis), mixed evergreen-deciduous, maple(Acer cappadocium), burans(Rhododendron arboreum), silver-fir(Abies pindrow), kharsu oak(Quercussemecarpifolia)and birch(Betula utilis).The d-d curve was inverse curvilinear for all species in the entire study area. The curve assumed an inverse curvilinear slope for the stands of smaller mean diameter, linear for the stands of intermediate mean diameter and bell shaped for the stands of larger mean diameter. The curves for burans, kharsu oak and alder, mixed and silver-fir, and birch forests were slightly convex, bell shaped, curvilinear, straight line and linear, respectively. Two light demanding species,Q. semecarpifoliaandAesculus indicahave been experiencing regeneration problem, whereas the other two light demanding species,A. nepaiensisandB. utilisexhibited moderate regeneration. Shade tolerantA. pindrow, A. cappado-ciumandR. arboreumexhibited satisfactory regeneration, but conversion of seedlings into trees was not satisfactory forA. pindrow.The relative protective value of 5 different forests was in the order: silver fir > kharsu oak > mixed deciduous-evergreen > mixed evergreen-deciduous > birch.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_02

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The forests of West Bengal have recently come under a comanagement initiative called Joint Forest Management. This paper will examine changing forestry regimes in southern West Bengal since the 1930s to suggest that the redefinition of forest management in the region since the mid 1980s cannot adequately be explained in terms of property rights. The nature of village community, overlapping jurisdictions of different agencies and groups in forest management, and the nature of expertise qualifying the scope of jurisdictions-that of foresters and villagers-are intersecting issues that have to be analyzed to understand the institutional politics of comanaging natural resources worldwide.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_03

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The highlands forests of southwestern Saudi Arabia are characterised by effective ecological, visual and economic values, long before the development of national social, administrative and economic institutions. This is witnessed both in the past especially before the establishment of a central state and in the meantime when local governments and individuals intervened by advocating and establishing consensus policies to regulate human interaction with the environment.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_04

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The volume of a tree's crown represents the accumulated historic crown surfaces integrated over time and environmental conditions. As such the crown volume of a tree should be correlated to the stem diameter, which represents accumulated historic wood increment. This study examines the relationship between crown and stem metrics of four tree species,Macaranga peltata, Schumacheria castaneifolia, Shorea megistophylla, andShorea trapezifolia, from an evermoist forest in southwestern Sri Lanka.Shorea megistophyllahad the highest correlation between crown volume and stem diameter of the four species (r2= 0.55). The addition of an inverted parabola, to represent historic crown surfaces not included by the current crown volume, improved correlations with stem diameter significantly, especially in the flat-topped pioneer species,Macaranga peltata. Schumacheria castaneifoliashowed poor correlations between stem and crown dimensions, suggesting that allocation to fruit and flower production may receive higher priority than diameter growth. The relative importance of current crown volume and cumulative crown volume in explaining variation in stem diameter offers insight into species life-history patterns.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_05

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Rates of litter decomposition and nutrient release from litter provide valuable information on the capacity of different tree species to replenish soil nutrients in degraded tropical areas. Leaf litter decomposition, leaf litterfall, plantation floor leaf litter, and mulch performance were studied for four indigenous timber species,Virola koschnyiWarb,Dipteryxpanamensis(Pittier) Record and Mell,Terminalia amazonia(J.F. Gmel.) Exell., andAlbizia gua-chapele(H.B.K.) Little, grown in mixed and monospecific plantations in the Atlantic humid lowlands of Costa Rica.Terminalia amazonialitter decomposed the fastest: no litter remained after 6 months. After 12 months,D. panamensis, A. guachapele, and the mixed litter decomposed completely, while 15% of the original weight ofV. koschnyilitter remained. Differences in decomposition rates were closely related to leaf nutrient content. Total annual leaf litterfall was highest inT. amazonia(872.9 g/m2), followed byD. panamensis, V. koschnyi, and the mixed plots.A. guachapelehad the lowest leaf litterfall (236.0 g/m2). The highest plantation-floor leaf litter was found inV. koschnyiandD. panamensis.Both litterfall and plantation-floor litter accumulation fluctuated least in the mixed plots.A. guachapeleandD. panamensismulch most positively affected maize seedling growth, followed by the mixed mulch. Recommendations are drawn from the results to suggest species choice for sustainable land management in the region.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_06

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Ever increasing demand for forest produce necessitates urgency to improve the productivity of the forest. Tree breeding and propagation technologies serve as important tools in tree improvement programs. However, breeding of tree species for sustainable gain takes years or even decades and seed raised plantation of any species is bound to exhibit variations in growth and other characteristics. Propagation by vegetative means assumes importance when desirable biotypes need to be multiplied in a short span of time. In this paper vegetative propagation techniques of tree species for higher biomass yield are discussed.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_07

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Examples of effective growth-and-yield model implementation and use are documented throughout the forestry world. However, in the perspective of sustainable forestry, comparing the development of management requirements with growth-and-yield research backgrounds, some doubts arise concerning basic research hypotheses. The conflict between the necessary simplification implied in models development and the essential complex nature of forests plays a key role in the issue. Furthermore, present modelling concepts stem from a traditional framework relying at the fundamental perception level on the enforcement of external regulations on the forest, having some predetermined optimal structure as a goal. If tomorrow's strategic planning places in the forefront of the framework Oldeman's paradox “objectives are best achieved by first forgetting them in favour of forest survival and complexity maintenance,” we will really face quite a sharp concept change. Yet, it is important to clearly focus the role of models as potential adjuncts to the professional judgement and wisdom of foresters given their rational scientific character as learning, communication and screening tools. What is attainable is not the high precision of quantitative predictions, at least as far as complex biological systems such as forests are concerned. Compact representations (e.g., minimal models and “modeles simples”) with few state variables and a biologically-driven content may provide reasonable indications on future states over a wide range of conditions, contributing to operational forest management guidelines within an adaptive framework.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_08

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

It has proven difficult to define operational goals for the maintenance of biological diversity in forested systems. Difficulty derives from two sources: focus on the elements encompassed by definitions of biodiversity encourages “paralysis by complexity”; and, several definitions tend to equate biological diversity with ecological diversity. Careful reading of the international agreements from UNCED '92 reveals both the scientific rationale and public concerns underlying maintenance of biodiversity. Linking management goals directly to public concerns avoids several dangers. Those dangers include managers being convicted of failure to achieve all imagined benefits of the concept “biodiversity,” researchers falling prey to bureaucratic expectation of science to fill policy instead of science to critically assess policy, and undue emphasis on the gap between the production and practical application of knowledge.

ISSN:1054-9811    

DOI:10.1300/J091v07n03_09

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor