Forest Ecosystems

Forests cover approximately 30% of the Earth’s land surface, account for over 75% of its standing biomass and house the majority of its biodiversity. Forests also play a critical role for humans, who rely on them for energy, shelter and clean water. By the simplest definition, a forest is a landscape dominated by trees, but a forest ecosystem comprises biotic and abiotic components – including invertebrates, microbes, birds and mammals, etc., along with physical environmental variables such as climate, soils and topography. Forest ecology, like other fields of ecology, is often divided into subdisciplines that focus on individual organisms, populations, communities or entire ecosystems. Although these distinctions are easily blurred, the study of ecosystems is generally characterized by the inclusion of the physical environment as an integral part of the system and an increased concern with the dynamics of organic matter, nutrients and water over interactions among specific organisms or species. This does not suggest that organisms and species are unimportant, but rather views their importance through their role in ecosystemlevel processes. Ecosystem science has grown rapidly over the past 30 years and has challenged ecologists to expand their breadth from traditional domains of biology into fields such as geochemistry, meteorology and hydrology. This shift has been partly driven by the realization that many environmental problems begin with an alteration of the physical or chemical environment, but can lead to a cascade of effects through other components of the ecosystem. Scientists have also begun to recognize the importance of forests in other aspects of the Earth’s environment, such as the composition of the atmosphere and the concentration of greenhouse gases.