Tropical forests, humid

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). 

Simon, A., Larsen, M. C., and Hupp, C. R. (1990). The role of soil processes in determining mechanisms of slope failure and hillslope development in a humid-tropical forest, eastern Puerto Rico. Geomorphology 3, 263-286. 

Another family of feedbacks involving biota arise via the process of evapotranspiration in which the rate of water vapor is transferred from the land surface to the atmosphere is mediated by plants. Several consequences have been proposed that include influences of biota on the greenhouse effect of water vapor as well as relative humidity and clouds. Lovelock (1988) suggested that tropical forests might be kept cool by increasing cloud cover in response to higher relative humidity released through enhanced evapotranspiration (via the clouds influences on albedo). Yet another connection arises because tree-covered land has different turbulence properties above it than bare soil, which also influences the cloud cover above. 

Medina, E., and E. Cuevas. 1994. Mineral nutrition humid tropical forests. Progress in Botany 55 115-129. 

Montagnini, F. 1994. Rehabilitating forest ecosystems in the humid tropics Recent experiences from Latin America. In Proceedings from lUFRO International Symposium on Growth and Yield of Tropical Forests. Sept. 26-Oct. 1, 1994 (Tokyo University of Agriculture and Technology. Fuchu, Tokyo, Japan), pp. 224-234. 

Buttress—structure that many trees of humid tropical forests grow at their base to stabilize the tree against the swaying forces of the wind. Buttresses can occur as broadened bases of the trunk, or as large, vertical projections from the base. 

Because orchids are so renowned for the beauty of their flowers, they are commonly cultivated in greenhouses, homes, and in warm and humid climates, in outdoor gardens. The most popular genera of horticultural orchids are Catteleya, Cymbidium, Dendrobium, Epidendrum, and Vanda, all of which are species native to tropical forests. 

Swamy, P.S., Sundarapandian, S.M., Chandrasekar, P. and Chandrasekaran, S. (2000). Plant species diversity and tree population structure of a humid tropical forest in Tamil Nadu, India. Biodiversity and Conservation, 9 1643-1669. 

The fluorescence images attributed to PSI in a chloroplast of the plant simplex var. metallica in Ref. [10] show a clear intensity modulation with local maxima coincident with local minima of PSII fluorescence, in contrast to our far-red images that show rather homogeneous distribution of PSI. This difference may be attributable to the abnormally large size of the grana (up to 1.9 pm) in this special plant which is found in shady, dense and humid tropical forest. 

The annual input rate of dead plant matter to soils in temperate regions, the net primary productivity of plants, is about 1 kg m 2 of carbon or 20 Mg ha-1 of dry matter. The annual input rate is perhaps 2 kg C m-2 or 40 Mg ha-1 of dry matter in humid tropical forests, and decreases to virtually zero to 0.1 kg C m-2 in deserts and arctic tundra. This input is part of the nonhumus organic matter, which includes original plant and microbial tissue and partially decomposed material. These nonhumus substances contain carbohydrates and related compounds, proteins and their derivatives, fats, lignins, tannins, and various partially decomposed products in roots and plant tops. The portion contributed by dead animal matter is insignificant because the... 

Silver, W. (1994). Is tropical nutrient availability related to plant nutrient use in humid tropical forests. Oecobgia 98, 336-343. 

Forest chemistry appears to be related to climate (mainly amounts of precipitation), geographical location (e.g. maritime influences) and the availability of elements in the soil (Jayasekera, 1993). Furthermore organisms are quite diverse and highly adaptive in element requirements and particularly in their tolerances. Due to the specific environment in an ecosystem without marked seasonal variations, predominantly poor soils and factors like high levels of precipitation, humidity or temperature, trees from tropical rain forests might have a rather dilferent chemistry from trees of the Northern Hemisphere. In order to understand the chemistry of heavy metals particularly in tropical forests more information is needed. 

Fig. 15.4. Simulated plant production (a), soil carbon (0-50 cm depth) and soil respiration (b), and nitrogen and phosphorus soil mineralization (c) for Hawaii humid tropical forest systems during 4.1 million years of soil development. Observed data are plotted on the graphs, and observed net primary production is assumed to be equal to 0.7 times annual soil respiration.

Determination of the physical environment in which our engineering system will operate is the first step in the process of learning about our system s environment. If we design a new type of a bicycle, we need to know if our bicycle is intended for use in a flat urban environment or in the mountains. Obviously, we need to know much more than that. For example, we also need to know if our bicycle will be used in the hot and dry desert climate of Niger or in the tropical forest climate, hot and humid, in Amazonia in Brazil. 

Coffee grows naturally In the understory of the wet tropical forest and bears some physiological characteristics of a shade plant (1). Air humidity is certainly an important factor in the devellopment of the plant,but the basic information on this topic is very short. In sequence of previous work ( 2) this, presents more data showing that low air humidity is a stress factor on photosynthesis and suggests that it affects not only stomatal conductance but chemical characteristics of the mesophyll related with photosynthesis. 

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