Progressive Deforestation Research Articles

Palaeoenvironmental developments in the Lake Tondano area (N. Sulawesi, Indonesia) since 33,000 yr B.P.

Geo(morpho)logical, sedimentological and ecological developments in the Lake Tondano area since ±33,000 yr B.P., and limnological changes in the moderately-sized lake situated at 680 m asl in the northern part of Sulawesi, Indonesia are discussed. First, the environmental setting of the lake is presented. Study of the regional distribution of lacustrine sediments, and a detailed analysis of their sedimentary facies (texture, organic matter content) suggest major changes in size and depth of the lake and in past sedimentation. Insight into the long-term development of the lake (sedimentation processes) is highly relevant for sustainable use of the present lake. Analysis of diatom assemblages provides further detail of the changing aquatic settings of the lake; lake levels rise quickly around 33,000 and 12,000 yr B.P., fall dramatically between ±30,000 and 13,000 yr B.P. and are lowered gradually since approximately 6000 yr B.P., following Early Holocene high lake levels. Drainage of the lake is affected by both volcanic depositional events and regional climatic events. Palynological analysis is indicative of local palaeoecological settings in the lake area and regional climatic change; a distinct, Late Pleistocene phase, with lower precipitation and lowered mean temperatures is inferred. Furthermore, progressive deforestation of the Tondano uplands is evident, as well as diffuse anthropogenic/volcanic vegetation disturbance from the early Mid Holocene onwards. Information from sedimentary facies, diatom assemblages and local palaeoecology (pollen) are integrated to reconstruct palaeoenvironmental settings and processes in the lake area. This record of environmental change as well as the pollen-based record of regional vegetation and climate change corroborates other palaeoenvironmental data derived from the few terrestrial sites in the region. The data attribute a greater magnitude of temperature and precipitation change in the region than is commonly deduced in studies based on marine faunal and sedimentary records. The Lake Tondano sedimentary record is highly suitable for further analysis aimed at determining the exact timing and amplitudes of environmental change in the SE Asian equatorial region.

Effects of deforestation pattern and private nature reserves on the forest conservation in settlement areas of the Brazilian Amazon

The effects of deforestation patterns, private nature-reserve extents and agricultural fallow periods on forest conservation were simulated for settlement projects in the Brazilian Amazon that produce a fish-bone pattern of occupation and where slash-and-burn agriculture is predominantly used. Data for simulation was obtained from previous work at the Bragantina region, the oldest agricultural frontier in the Brazilian Amazon. Forest conservation was evaluated using the size of remnant forest fragments, the amount of interior habitat, the connectivity among fragments and the extent of fragmentation. Results showed that the best scenario for forest conservation is the maintenance of 80% of the lot as privatereserve using deforestation pattern that allow to group the reserves from different farmers at the end of the lot. When private-reserve coverage is bellow 80% of the landscape, forest conservation status will be influenced by the deforestation pattern. Some patterns (e.g. random location of deforestation plots) will then be particularly deleterious, producing a highly fragmented landscape, while other patterns (e.g., progressive deforestation from one edge) can allow the maintenance of large forest fragments. To get forest conservation in these cases, private-reserve extent and deforestation pattern should be considered together. Considering both forest conservation and agricultural use, progressive patterns of deforestation (or land use) in a lot of 2,000m by 500m, with private nature-reserves covering 50% of the landscape seems to be the best compromise. To guarantee the private forest preservation, these forests should be pre-established when settlements are planned and grouped at the end of the lots.

An analysis of deforestation: Metrics used to describe pattern change

Cartographic modeling was used to examine the influence of deforestation on landscape pattern metrics. Progressive deforestation resulted in an increase in the spatial heterogeneity, fragmentation, and edge characteristics of a landscape while connectivity attributes varied with deforestation stage. Pattern changes in heterogeneity and edge characteristics were curvilinear, with metrics changing direction at the half-way point of deforestation. The progressive loss of forest enhanced edge length, interspersion, and convexity. There was an exponential decline in interior forest and mean patch size, while patch density and interpatch distance increased. The variability displayed by several pattern metrics reflect the unpredictability in patch disappearance. The relative contribution of each metric for discriminating between contiguous and fragmented landscape conditions was ranked using discriminant analysis. The results suggested that the mastery of landscape analysis can be directly linked to the choice of the pattern metric. Percent forest interior, contiguity, and convexity were highly significant ( P<0.001). Forest loss was also significantly reflected by mean patch size, number of patches, mean patch density, and interpatch distance. Metrics that contributed little to discrimination displayed unpredictable behavior or exhibited high variability about their mean values. This paper develops an approach for monitoring the influence of deforestation on the landscape, and examines how pattern-related habitat components are affected by deforestation. The ability to quantify pattern change resulting from deforestation has direct implications to resource management and wildlife habitat assessment. Descriptions of pattern change accompanying deforestation provide a critical component of habitat analyses.

Household energy needs of a village in the Rayalaseema area of Andhra Pradesh, India

Energy shortages in rural areas have several far-reaching ill-consequences. The scarcity of fuelwood forces people to use animal dung and crop residue as fuel, reducing the soil fertility and productivity. Progressive deforestation adversely affects the environment. Women and children in villages walk long distances and spend more time in searching for fuel. For effective energy planning, it is necessary to understand the energy-use patterns of different categories of farmers in village ecosystems and the influence of income and family size on it. This paper reports such a study conducted in a village in the State of Andhra Pradesh in India where dryland agriculture is pursued. The household energy-use patterns observed in the village clearly show that most energy is utilized for basic survival tasks such as cooking, cleaning, fetching fuel, water and other necessities of life. Commercial energy, which accounts for 6.5% of the total energy consumption of households, is used exclusively for lighting. A number of measures have been suggested for enhancing the efficiency of energy use in rural household systems, which include the design and installation of a fuel-efficient improved chulha, with dampers, baffle and a grate in the combustion chamber, installation of family size biogas plants, planting of hardwood trees on field bunds, energy plantation on marginal and waste lands, utilization of solar photovoltaics for power generation, installation of windmills for lifting water, and briquetting and pelletization of groundnut shell, and farm and forest residues. A well-knit and coordinated infrastructure has to be developed for successful implementation of the above measures. Local skill and participation, especially of artisans and women, should be encouraged and should be supplemented by appropriate training and monitoring. An energy utilization system based on local resources can improve productivity and standards in all spheres of rural living.

Confrontation des données polliniques et anthracologiques

North Western France (Armorica) has undergone during the Holocene, under human impact, a progressive deforestation, while an atlantic regressive heathland spread gradually. Palynological analysis applied to wet grounds and to archaeological sites (with specific data processings) and those of anthracology (identification of charcoal and ring analysis) converge towards an original methodological approach for the reconstruction of the principal stages of the evolution of the environment.

The Use of Dung as Fuel : an Ethnographic Example and an Archaeological Application

Modern plant use and garbage disposal practices in an Iranian village were observed in order to provide a framework for the interpretation of plant remains from ancient Malyan, a third millennium B.C. urban center in southern Iran. The ethnoarchaeological model suggested that many carbonized seeds originate in dung cake fuel. By applying this proposition to the archaeobotanical material from Malyan, it was possible to corroborate the evidence provided by the independent charcoal analysis for progressive deforestation during the third millennium.

Palaeoecological investigations at Ballynagilly, a Neolithic and Bronze Age settlement in County Tyrone, Northern Ireland

The Neolithic-Bronze Age occupation site at Ballynagilly was covered by blanket peat and surrounded by a deep mire. Stratigraphic investigations, pollen analysis and14C dating were used to investigate the history of the area and to relate this to the prehistoric occupations. A series of14C measurements from the mire were used to establish a deposition rate curve from which a time scale for the vegetational history was derived. This was also used to correlate the vegetation history with14C dated prehistoric occupations. Organic accumulation began in the deep mire about 8000 B.C. (the notation A.D./B.C. is used to denote a conventional14C age less 1950 years) and the earliest blanket peats began forming around 1000 b.c. In the early Littletonian Stage (Postglacial) a juniper phase gave way to birch and willow at *7450 B.C. (* is used to denote a date derived from the deposition rate curve). Until *6050 B.C. there was a period of low water level with a rich mire vegetation. Elm, oak, hazel and pine entered simultaneously at *6050 B.C. creating a dense forest cover. Alder first appeared at *4970 B.C. but did not expand until *3500 B.C. The mid-Postglacial was examined in detail and showed evidence of Neolithic forest clearance involving burning. Charcoal of pine, oak and hazel,14C dated to ca. 3200 B.C. was discovered. This date coincides with those for a Neolithic house and other associated features. The Neolithic clearance phase lasted some hundreds of years with periods of minor forest regeneration. During this phase different types of agriculture may have been used. A total recovery of the forest, albeit with a different composition, was deduced to have taken place before new clearance in Beaker times at ca. 2000 B.C. Somewhat before this, at *2200 B.C., the final decline of pine pollen occurred but was apparently unconnected with human activity. Heath began to develop at *1800 B.C. and increased in extent following Early Bronze Age clearance of scrub woodland at * 1650 B.C. Various clearance episodes from this time through to *200 B.C. caused a further progressive deforestation. Brief regeneration after *200 B.C. was followed by indications of locally wetter conditions and renewed deforestation at A.D. *450. Despite some scrub regeneration around A.D. *800 continuing pressures on the woodland culminated in a open landscape by A.D. *1500.