Forest disturbances

Carbon sequestration in forest disturbed by human activity is lower than in forests less seized by humans. 

Overpeck, J. X, Rind, D., and Goldberg, R. 1990. Climate-induced changes in forest disturbance and vegetation. Nature 343, 51-53. 

If one is studying the transport of material through the tree canopy of a forest, it is most desirable to disturb the natural environment as little as possible in making a wind measurement in the canopy. An extremely sensitive wind system is necessary because one would expect the winds to be extremely light. Also, it may be necessary to make supporting measurements both above and below the canopy, so that a wind speed profile is obtained. 

Land use changes in the tropics have resulted in a landscape characterized as a mosaic of logged forests, cleared fields, and successional forests. This results in the transformation from extremely fire resistant rainforest ecosystems to anthropogenic landscapes in which fire is a common event (16, 17), Fires occur in disturbed tropical forests because deforestation has a dramatic effect on microclimate. Deforestation results in lower relative humidities, increased wind speeds, and increased air temperatures. In addition, deforestation results in increased quantities of biomass that are susceptible to fire. This biomass may be in the form of forest slash, leaf litter, grasses, lianas or herbaceous species (16, 18). 

Biogeochemical cycling in forests includes elemental inputs, exports, and a complex set of physical, chemical and biotic processes which comprise internal nutrient cycles (Fig. 1). Any disturbance, whether anthropogenic (i.e. 

Biomass Redistribution Associated with Deforestation and Fire. The influence of deforestation on biogeochemical cycles is dependent upon a number of factors associated with the unique characteristics of the ecosystem (climate, soils, topography, etc), the quantity of the total nutrient pool stored in aboveground biomass (Table II), and the level of disturbance (i.e. the degree of canopy removal, soil disturbance, and the quantity of wood or other forest products exported from the site). The quantity of biomass consumed by one or more slash fires following deforestation can also dramatically increase nutrient losses, influence post fire plant succession, and hence, postfire biogeochemical cycles. 

Table I. Elemental inputs and losses of elements in the absence of disturbance in selected forest ecosystems ...

Forest Location Disturbance Status Biomass Reference... 

Earthquake-caused landslides A major disturbance to tropical forests. Science 205, 997-999. 

Runkle, J.R. (1982). Pattern of disturbance in some old-growth mesic forests of eastern North America. Ecology, 63,1533-46. 

Fig. 34. Horsfieldia glabra (Bl.) Warb. Plants of Indonesia. East Bali, Karangasem, South slope of Gunung Agung, 1-2 km Southwest of Basket. Altitude 750 m. 8° 21, South-115° 26 East in disturbed forest in ravine canopy. 

Wagai R, Sollins P (2002) Biodegradation and regeneration of water-soluble carbon in a forest soil leaching column study. Biol Fertil Soils 35 18-26 Wardle DA, Ghani A (1995) A critique of the microbial metabolic quotient (qC02) as a bioindicator of disturbance and ecosystem development. Soil Biol Biochem 27 1601-1610... 

Global climate change, air-quality degradation (coal, oil), lake acidification and forest damage (coal, oil), land disturbance and others, if hydrogen is produced by fossil fuels ... 

Berry, C. R. White Pine Emergence Tipbum, a Physiogenic Disturbance. U.S. Department of Agriculture Forest Service, Station Paper 130. Asheville, N.C. Southeastern Forest Experiment Station, 1%1. 8 pp. 

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