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Ecological Basis for Rainforest Management
from PNGAF MAGAZINE ISSUE # 9D 2 of 15th October 2021 THE DEVELOPMENT OF PNG'S FOREST MANAGEMENT SYSTEMS
by rbmccarthy
Ecological Basis for Rainforest Management
Management and Treatment of the Forest. The need to establish an ecological basis for PNG rainforest management yet ensuring a multiple use of forest resources.
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FAO estimated in 1976, that then with a population of some 2 million people, shifting agricultural systems cleared approximately 200,000 hectares of regrowth and virgin forest annually.
PNGAF MAGAZINE ISSUE # 9B - 4 of 6th April 2021, addressed in detail, the moist tropical rainforest life cycle and forest dynamics and its applicability to PNG’s forests. For foresters to understand rainforest management, it is necessary to examine the life cycle of climax rainforest vegetation. Herein lies the basis for successfully managing rainforest vegetation, or indeed, any vegetation. Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna, and ecosystems in forests.
The general pattern of growth for any area of climax (mature) rainforest is one of an overstorey of large trees, most of which tend to be light demanders throughout most of their life. Beneath these trees, are one or more lower stories which contain both smaller individuals of over storey trees and mature trees of lesser stature. Large climbers are present in the upper canopy, epiphytes occur on the trunks and branches, shrub layers and in places, a herb layer is found in the undergrowth, while on the ground are fallen leaves, seedlings and seed. Competition is severe and mortality amongst seedlings is high. In PNG’s mixed rainforest stands, the actual composition is largely a matter of chance, depending not only on the size of the opening but upon the species present as seedlings and /or saplings when the opening is formed, and the climatic conditions that exist at the time of creating the opening.
Forest dynamics describe the underlying physical and biological forces that shape and change a forest ecosystem. The continuous state of change in forests can be summarized with two basic elements: disturbance and succession.
Rainforest silviculture is the manipulation of the forest to favour certain species and thereby enhance its value to Man. It is not a science (in its own right), but it is applied ecology. The forester needs to understand all the factors involved in regenerating the more desirable species. This includes flowering and fruiting, seed dissemination, germination, distribution and development of regeneration, size class distribution, and pattern of growth leading to climax vegetation in the rainforest. Rainforest soils tend to be generally infertile and deficient in plant nutrients. It is probably that infertility, which provides the main limit to production on rainforest sites. Rainforest plants are clearly adapted to making the best use of these infertile sites. Sustainable utilisation of the rainforest depends on working within the limits of ecosystem nutrient cycles. Shifting agriculture works by using the capacity of trees to grow on acid
infertile soils and bring nutrients from the soil into the biomass. During the bush fallow period, nutrients reaccumulate in the vegetation, partly from the soil and partly from rain.
Shifting agriculture and selective removal of trees do not cause serious permanent depletion. More complete biomass utilisation for wood chips or in plantation forestry will deplete ecosystem nutrients unless balanced by rain and soil inputs.
Rainforest silviculture will be successful so long as it is practised within the biological limits of the forest.
Foresters have no control over changes to the climate. Yet, forests are sensitive to climate. Climate change can have a great effect on the dynamics of the ecosystem.
