摘要:

Responses of juvenile white oak(Quercus albaL.) and loblolly pine(Pinus taedaL.) to simulated acid precipitation (pH 4.8, 4.2, and 3.6), as influenced by soil fertility, were examined. Height and stem diameter growth of white oak decreased with increasing rainfall acidity, although the height response was confined to the high fertility treatment, and root mass was reduced by pH 3.6 rains as well. Height and diameter growth also declined with increasing acidity in loblolly pine, and shoot and root mass and root length and specific length were reduced in low fertility by pH 3.6 rains. Direct foliar injury increased with increasing acidity in loblolly pine, but pH 3.6 rainfall stimulated mycorrhization of this species. Foliar Ca, Mg, and Cu were reduced in both species by pH 3.6 and pH 4.2 rains as was S by the former. Conversely, the Fe concentration was elevated by pH 3.6 and pH 4.2 rainfall in loblolly pine as was Zn by the former. Foliar Al increased with increasing acidity in both white oak and loblolly pine, a response partially attenuated by high soil fertility. Xylem pressure potential of loblolly pine that had received pH 3.6 rainfall declined below that of other treatments during a simulated drought episode.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_01

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Fertilization with three controlled release nutrient formulations, Sierra 16-6-10 % Minors, High N 24-4-7, and Osmocote 17-7-12, and partial shade provided by mesh solar barriers were evaluated for their effects on establishment of bare root Jeffrey pine(Pinus jeffreyiGrev & Balf.) seedlings on an eastern Sierra Nevada reforestation site. The Osmocote formulation proved effective in stimulating seedling growth with little impairment of survival, particularly at a medium application rate of 20 g per seedling, although a low rate of 10 g and a high rate of 30 g were also effective. Growth responses to the Sierra and High N formulations were generally poor, and the high application rate of the latter induced excessive mortality. Foliar N, P, K, S, Fe, Zn, Cu, B, and Al varied significantly among fertility treatments, but enhanced N nutrition largely accounted for growth stimulation. Solar protection also increased growth, attributable to improved water relations as indicated by higher xylem water potentials, but was ineffectual in elevating seedling survival.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_02

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Age and diameter distributions are powerful tools for assessing changes in forest structure and composition over time. This study analyzed the age distribution of 2,345 trees from 487 plots in the eastern Washington Cascades to document increases in per-hectare tree densities and shifts in species composition since Euro-American settlement. Diameter distributions of these trees plus an additional 814 snags, stumps, and logs were analyzed to determine the extent and pattern of structural and compositional change resulting from post-settlement fire exclusion and preferential harvest of large ponderosa pine(Pinus pon-derosaDougl. Ex Laws.) and western larch(Larix occidentalisNutt.). Per-hectare densities of most species increased following settlement, with shade-tolerant/fire-intolerant species showing the biggest gain. A comparison of diameter distributions for live and dead trees indicates existing stands may not provide snags and logs of adequate dimensions for future habitat needs. Changes in forest structure and composition over the past century increase risk for insect outbreaks, diseases, and catastrophic wildfires.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_03

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper presents estimations of aboveground tree biomass (combined for boles and branches) in Nepal'sSchima-Castanopsisdominated warm-temperate forests. The biomass estimations are presented for five forest stands purposively sampled in a larger study to represent different harvesting intensities. Two categories of biomass estimates are provided: (1) for living trees that are standing, and (2) for cut trees that have been removed. Biomass of standing trees were estimated by using diameter at breast height (dbh) and total height measurements as predictor variables in appropriate regression models. Biomass of cut trees were estimated in two steps: measurements of stump diameters and heights were used first to predict dbh and total heights of cut trees; these values were then regressed to obtain biomass estimates for the missing trees. Data were gathered from 2,361 live trees and 2,962 stumps in 170 sample plots across the five forest stands. Estimates of mean standing-alive biomass ranged from a minimum of 16 ton/ha in the severely disturbed forest to a maximum of 479 ton/ha in a relatively undisturbed (reference) forest. Estimates of mean cut biomass ranged from a minimum of 24 ton/ha in a second reference forest to a maximum of 183 ton/ha in the severely disturbed forest. The biomass estimates in the relatively-undisturbed, reference forests are well above the 95% upper confidence interval of the global mean. Similar findings of high productivity have been reported for temperate forests of the Central Himalaya in India and Eastern Himalaya in Sik-kim. The findings of this study in the Nepalese Central Himalaya support the conclusion that productivity potential is high in the temperate Himalayan forests. The study's findings and methodology should be useful for preliminary development of guidelines in the region to regulate forest biomass growth, yield, and harvest.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_04

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Conservation of biodiversity provides for economic, social, and environmental sustainability. Intentional management is designed to manage conflicts among groups with conflicting interests. Our goal was to ascertain if intentional management and principles of conservation of biodiversity could be combined into upland and riparian forest management strategies that would be applicable to various land ownerships and, consequently, help resolve land allocation problems associated with timber supply and threatened wildlife.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_05

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Fertilization with two controlled release nutrient formulations, High N % Minors 22-4-6 and Customblen 14-7-10, and ectomycorrhizal inoculation withPisolithus tinctorius(Pers.) Coker & Couch were evaluated for their effects on growth, establishment, and nutrition of containerized Jeffrey pine(PinusjeffreyiGrev. & Balf.) on an eastern Sierra Nevada surface mine. Basidiospores from sporocarps collected at the mine were used to induce mycorrhizal formation in the nursery, and fertilization rates were 10, 20, or 30 g applied at outplant-ing. Mycorrhizal inoculation enhanced survival overall, but for both fertilizers, the 30 g application increased mortality except for inoculated seedlings that received High N. Seedling survival was unaffected by 10 or 20 g of either fertilizer, however. The growth response to High N exceeded that to Customblen, and among the High N treatments, growth stimulation by the 20 g application surpassed that by 10 or 30 g. Foliar N concentrations were increased by fertilization during the second and third growing seasons, more in the High N than Customblen treatments, and N concentrations generally increased with amendment application rate. Excessive uptake of B, supplied in high amounts by Customblen, likely resulted in the relatively poor performance of seedlings that received this formulation. Within most of the fertilization treatments, inoculated seedlings had lower foliar concentrations of several metallic elements, notably Mn and Al, than uninoculated seedlings during the first growing season, which may have contributed to the enhanced survival of the former.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_06

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A key component in the management of the forest resource, be it for wood production, conservation or both, is accurate growth and yield information. The incorporation of remotely sensed imagery into growth and yield calculations can offer potential solutions to some of the problems of predicting forest growth rates. In particular, the repeat coverage of the satellite sensors such as Landsat Multi Spectral Scanner (MSS) data has allowed the development of long-term archives of the changing environmental and growth conditions of forests.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_07

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Chiapas is among the poorest of Mexico's states and has been characterized by political instability, civil unrest, escalating population and widespread deforestation. Recent history and current land use issues were investigated in two highland communities, Juzanajab and Palma Real, to assess the factors influencing forest management decisions and the potential for sustainable forest use on communally-owned land. The two communities contrasted markedly, Juznajab possessing a larger forest resource, a higher population density, but a lower degree of marginalization. These differences were found to result from the contrasting historical development of the two areas, particularly with respect to the pattern of land use prior to agrarian reform and the impact of agrarian reform itself. More recently, agricultural intensification and intensive timber harvesting have impacted on the forest resources of both communities. The communities also differed in pattern of forest use, five and fourteen different forest products being used in Palma Real and Juznajab, respectively. Results also highlighted the importance of social structure: both communities were highly aware of the danger of social disruption, reflecting the history of conflict in the area. Such concerns encourage a cautious approach to communal resource management, where social security may be valued more highly than economic returns. In terms of the available forest resource, greater potential for community-based management exists in Juznajab than Palma Real. However, social conditions appear to be more conducive to community co-operation in Palma Real. These case studies highlight the significant challenges to community-based forestry which exist in Chiapas. It is suggested that collaborative pilot projects, involving the provision of economic incentives to encourage sustainable forest management, hold greatest promise for future developments in this area.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_08

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

HANDMADE FORESTS. Cyr, Helene. 1999.New Society Publishers. Ga-briola Island, B.C. & Stony Creek, CT, pp. 144, US $19.95.Reviewed by Graeme P. Berlyn.

ISSN:1054-9811    

DOI:10.1300/J091v09n03_09

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor