Exotic Forest Plantations Research Articles

Soil and solution chemistry under pasture and radiata pine in New Zealand

The conversion of hill country pasture to exotic forest plantations is occurring rapidly (70,000 ha yr−1) in New Zealand. Impacts of this land-use change on soil properties, soil fertility, and water quality are only beginning to be investigated. This study examines the effects of radiata pine (Pinus radiata) on soil and soil solution chemistry, in a region of low atmospheric pollution, 20 years after plantation establishment, assuming that the pasture and pine research sites had comparable soil properties before planting pine. The primary effects of conversion on soil chemistry were a decrease of organic carbon in the mineral soil that was balanced by an accumulation of the surface litter layer, a decrease in soil N, soil acidification, and increased pools of exchangeable Mg, K, and Na. Soil solution studies revealed a large input of sea salts by enhanced canopy capture of sea salts that contributed to much larger solute concentrations and elemental fluxes in the pine soil. Sea salts appear to accumulate in the micropores of pine soil during the dry summer period and are slowly released to macropore flow during the rainy season. This results in a progressive decrease in solute concentrations over the period of active leaching. While chloride originating from sea salt deposition was the dominant anion in the pine soil, bicarbonate originating from root and microbial respiration was the dominant anion in the pasture soil. Carbon dioxide concentrations in the soil atmosphere were 12.5-fold greater in the pasture soil than in the pine soil due to greater rates of root and microbial respiration and to slower diffusion rates resulting from wetter soil conditions in the pasture. Although elemental fluxes from the upper 20 cm of the soil profile were substantially greater in the pine soil, these losses were compensated for by increased elemental inputs resulting from nutrient cycling and enhanced canopy capture of sea salts.

Electricty generation from woody biomass fuels compared with other renewable energy options

The future New Zealand biomass resource from exotic plantation forest arisings could supply 970 GWh/year by the year 2002. Associated wood processing residues could supply 280 GWh/year. Purpose grown fuelwood plantations could supply 2060 GWh/year with potential to rise to 10,000 GWh/year by 2012. Currently the annual electricity demand is around 30,000 GWh 70% of which is generated by hydro power. Natural gas, a resource with estimated reserves of only approximately 14 years currently supplies 25% of generating capacity. This paper describes how part replacement of gas by biomass could be a feasible proposition for the future. Life cycle cost analyses showed electricity could be generated from arisings for (US)4.8–6 c/kWh; from residues for (US)2.4–4.8 c/kWh; and from plantations for (US)4.8–7.2 c/kWh. For comparison the current retail electricity price is around (US)4–5.5 c/kWh and estimates for wind power generation range from (US)5–10 c/kWh. Future hydropower schemes will generate power between (US)4–9 c/kWh depending on site suitability.

Regulating Afforestation for Water Conservation in South Africa

SYNOPSIS It is necessary to regulate afforestation in South Africa because of the high demand exotic forest plantations make on the scarce water resources of the country. The present procedure and information base for the regulation of afforestation with exotic plantations in South Africa are useful, but rely on a large degree of subjectivity and exclude recent research information from the procedure. The problem of regulating afforestation can also be dealt with as a simple linear programming model. Solution of the linear programming model requires quantitative and qualitative information obtained by using different methods. The use of the Analytic Hierarchy Procedure (Saaty, 1983) as a qualitative method to determine a preference rating for the water demand of five user categories, i.e. terrestrial ecosystems, river ecosystems, industry, irrigation and dam storage, is demonstrated. Quantitative relationships between afforestation and annual water yield are updated. We suggest the use of this new procedure in preference to the present one. Suggestions are made for incorporating hydrological aspects such as spatial variation of evapotranspiration in catchments, critical low flow constraints and the influence of rotation age on water use. The need for accurate determination of evapotranspiration, not only of exotic plantation, but also of natural vegetation being replaced by the plantations, is emphasised.

Woodland structure, destruction and conservation in the Copperbelt area of Zambia

Abstract Between 1937 and 1983 a total of 391 400 ha of woodland, representing 51% of the 768 900 ha in the Zambia Copperbelt, had been deforested for industrial and household woodfuel. This has occurred in spite of a forest reservation programme that increased the area in forest reserves from 31 707 ha in 1942 to 252 715 ha in 1965. Between 1965 and 1980 the reserved forests were reduced to 246 930 ha and since then the area has remained static. The rapidly growing demand for charcoal by the increasing urban population, and the growing problem of acid dust and rain pollution from copper smelters, pose serious threats to forest conservation in this industrial region of Zambia. Current forest conservation is restricted to the establishment of exotic forest plantations and recently deforested areas are left to regenerate naturally. Forest destruction and conservation in the Copperbelt area were studied and the structure of old-growth and coppice woodland stands at 9 and 14 sites, respectively, investigated during 1982–1984. The Copperbelt vegetation is dominated by Brachystegia-Julbernardia woodland. Mean species diversity of 24·40·1 ha −1 in coppice stands was higher than that of 18·9 found in old-growth stands. Stem density in coppice was 3·3 times that observed in old-growth woodlands. The majority of species (over 50%) in both old-growth and coppice were represented by less than 11 stems per sampling plot. Mean basal area at breast height in coppice aged 19–23 years was 14·33 m 2 , which was 95% of the mean basal area of 15·15 m 2 found in old-growth woodlands.

Towards predicting outbreaks ofPseudocoremia suavis(Lepidoptera:Geometridae)

In the light of a recent epidemic of Pseudocoremia suavis in mature, heavily stocked stands of Douglas fir, the need for a simple routine survey for the common defoliator of exotic forest plantations is discussed. Detailed records of 8 consecutive generations of P. suavis were obtained from an energy flow programme. Population fluctuation showed a marked correlation with rainfall in the formative month of a given generation. Consequently, a simple routine survey, based on the host's silvicultural condition and on precipitation, is proposed.

Mycorrhizal fungi of exotic forest plantations

Mycorrhizal fungi of exotic forest plantations

Spiral Grain in East African Exotic Softwood Forest Plantations

Spiral Grain in East African Exotic Softwood Forest Plantations

Proceedings of the House of Delegates of the National Dental Association

Using science knowledge to guide conservation action remains difficult; communication gaps persist, especially between scientists and other stakeholders including policy makers. Here, we demonstrate how we have managed to integrate scientific knowledge into consensually formulated conservation actions in the Taita Hills, Kenya. GIS-based least-cost modelling, together with sociological and forest characteristics were used to determine and prioritise the most appropriate areas for reforestation from a set of exotic forest plantations targeted for conversion into indigenous forests. This prioritisation was done through a succession of three workshops (on site) used to reach multiple stakeholders, build consensus on conservation actions, and formulate an implementation framework. Indigenous tree nurseries have now been established to provide planting stock for the reforestation activities agreed upon after the final workshop. The key lesson we learned from this exercise was that bridging the gap between science and conservation demands a very open, inter-disciplinary strategy, initiated and executed jointly by a diverse group of people that includes the Government (policy-makers and implementers), NGOs (conservationists and environmental advocates), scientists (researchers), conservationists and the local community. This study provides a pointer for what it may take to integrate human issues with sustained environmental management based on scientific knowledge.