ENSP101 Chapter 12 Biodiversity Preserving Landscapes 12 2 World Forests Forests and woodlands occupy some 4 billion hectares or about 30 of the world s land surface Grasslands pastures and rangelands cover about the same percentage o Together these ecosystems supply many essential resources such as lumber paper pulp and grazing land for livestock o They also provide vital ecological services including regulating climate controlling water runoff providing wildlife habitat and purifying air and water o These biomes are also among the most heavily disturbed because they re places that people prefer to live and work Forests are widely distributed but the largest remaining areas are the humid equatorial regions and the cold boreal forest of high latitudes o Forest any area where trees cover more than 10 of the land o This definition includes a variety of forest types ranging from open savannas where trees cover less than 20 of the ground to closed canopy forests in which tree crowns overlap to cover most of the ground o Among the forests of greatest ecological importance are the primeval forests that are home to much of the world s biodiversity ecological services and indigenous human cultures o Sometimes called frontier old growth or virgin forests these are areas large enough and free enough from human modification that native species can live out a natural life cycle and ecological relationships play out in a relatively normal fashion o Primary forests forests composed primarily of native species in which there are no clearly visible indications of human activity and ecological processes are not significantly disturbed o Globally about 1 3 of all forests are categorized as primary forests Wood plays a part in more activities of the modern economy than does any other commodity o Total annual world wood consumption is about 4 billion m3 o International trade in wood and wood products amounts to more than 100 billion each year wood consumption o Paper pulp the fastest growing type of forest product accounts for nearly a 5th of all o Global demand for paper is increasing rapidly o Fuel wood accounts for nearly of global wood use o More than of the people in the world depend on firewood or charcoal as their principal source of heating and cooking fuel o Demand for fuel wood which is increasing at slightly less than the global population growth rate is causing severe fuel wood shortages and depleting forests in some developing areas especially around growing cities o About 1 5 billion people have less fuel wood than they need and many experts expect shortages to worsen as poor urban areas grow Because fuel wood is rarely taken from closed canopy forest however it doesn t appear to be a major cause of deforestation o Approximately of the world s forests are managed for wood production o Ideally forest management involves scientific planning for sustainable harvests with particular attention paid to forest regeneration Monoculture agro forestry intensive planting of a single species an efficient wood production approach but one that encourages pests and disease infestations and conflict with wildlife habitat or recreation uses Tropical forests are being cleared rapidly There are many causes for deforestation o In Africa forest clearing by subsistence farmers is responsible for about 2 3 of the forest destruction but large scale commercial logging also takes a toll o In Latin America the largest single cause of deforestation is due to expansion of cattle ranching o Fires destroy about 350 million hectares of forest every year o As global climate change brings drought and insect infestations to many parts of the world there s a worry that forest fires may increase catastrophically o Biofuel production Nearly 12 of all world forests are now in some form of protected status but the effectiveness of that protection varies greatly o Ironically one measure being promoted as a way of saving tropical forest could result in more destruction of primary forests at least in the short run o People also are working on the grassroots level to protect and restore forests in Debt for nature swap forgiveness of international debt in exchange for nature protection other countries in developing countries Temperature forests are also threatened o Logging o Roadless Rule A Clinton era ban on logging road building and other development on the lands identified as deserving of wilderness protection in the Roadless Area Review and Evaluations RARE o A much greatest threat to temperate forests may be posed by climate change insect infestations and wildfires all of which are interconnected In the 1990s the US Forest Service began to shift its policies from a timber production focus to ecosystem management which attempts to integrate sustainable ecological economic and social goals in a unified systems approach o Some of the principles of this new philosophy include Managing across whole landscape watersheds or regions over ecological time scales Considering human needs and promoting sustainable economic development and communities Maintaining biological diversity and essential ecosystem processes Utilizing cooperative institutional arrangements Generating meaningful stakeholder and public involvement and facilitating Adapting management over time based on conscious experimentation and collective decision making routine monitoring 12 2 Grasslands After forests grasslands are among the biomes most heavily used by humans o Because grasslands chaparral and open woodlands are attractive for human occupation they frequently are converted to cropland urban areas or other human dominated landscapes o Worldwide the rate of grassland disturbance each year is 3x that of tropical forest o Although they may appear to be uniform and monotonous to the untrained eye native prairies can be highly productive and species rich By carefully monitoring the number of animals and the condition of the range ranchers and pastoralists people who live by herding animals can adjust to variations in rainfall seasonal plant conditions and the nutritional quality of forage to keep livestock healthy and avoid overusing any particular area Conscientious management can actually improve the quality of the range o When grazing lands are abused by overgrazing especially in arid areas rain runs off quickly before it can soak into the soil to nourish plants or replenish groundwater o Springs and wells dry up o Seeds can t germinate in the dry overheated