Tropical Agro-Ecosystems

Transcription

1 ropical Agro-Ecosystems to Dry ropical Vegetation Acid soils Alkaline soils From ain Forests to Deserts mm months mm 9-4 months mm 4-0 months to Dry ropical Vegetation Vegetation Distribution in the ropics Acid soils Alkaline soils ainforest easonal Forest avanna Dry avanna hrubland teppes emi-deserts Deserts mm months mm 9-4 months mm 4-0 months ropical Climate-Vegetation Zones ropical Climate-Vegetation zones Desert emi-desert hrubland steppe Dry savanna savanna wamp Formations ropical forests (seasonal and rainforest) ropical highlands Vegetation months Deserts 0 < 250 emi-deserts 1 < 250 hrubland steppes ain Distribution of rain Percent land area short wet season Dry savannas or 2 wet seasons savannas wet seasons ivers run all year Forests easonal, evergreen, and rain forests 29% 18% 29% 22%

2 Hot Dry Deserts and emi Deserts (Less than 250 mm rain) D D ahara, large parts of Egypt, D Libya, Algeria, Mauritania Central Australian D Atacama desert D oils = Aridisols May have problems with salt accumulation Generally alkaline in nature Can be fertile if irrigated Little agriculture practiced emi-arid hrubland teppe Grassland/hrubland avanna ( mm, 2-4 months wet season) t outhern border t of ahara t t tdesert, west India outhern Mexico t Australia 2-4 humid months, mm oils = Aridisols May have problems with salt accumulation Generally alkaline in nature Can be fertile if irrigated ome irrigated agriculture, ranching t emi-arid hrubland teppe Grassland/hrubland avanna ( mm, 2-4 months wet season) avanna (47%) ( mm, 4-9 months) Drought resistant cereals orghum Millet Various pulses High potential if water is available Dry avanna (29%) hort wet season wo wet seasons Monsoon, long wet season avanna (18%) wo wet seasons Dry avanna Bushland avanna ( mm, 4-6 months) 4-6 humid months, mm hort rainy followed by long dry season ainfed and irrigated agriculture Grazing Annual crops: sorghum, sweet potatoes, beans, cowpeas Perennial crops with irrigation Dry avanna Bushland avanna wo wet seasons, low rainfall mm Perennial crops - marginal, need irrigation Cassava, pulses, maize, sorghum, millet Drier parts used for grazing

3 Dry avanna Bushland avanna ub Humid avanna Woodland avanna Monsoon, one long rainy season mm Extensive areas of Asia and Africa Highly variable climate and production Perennial Only drought tolerant - sisal, cashew In wetter areas, tea important Groundnuts, cotton, sorghum, millet, maize ice when irrigated angelands limited by dry season ainfed and irrigated agriculture hailand Ghana Northern Brazil 7-9 humid months, mm ivers have water all year round Discontinous canopy with continuous grass or woody shrub ground cover ub Humid avanna Woodland avanna wo wet seasons with high rainfall mm Major agricultural land Easy to clear, mechanization possible Where soils permit, highly productive Much converted into savanna of grasslands Fires Continuous cultivation ub Humid avanna Woodland avanna, higher rainfall regions Perennial: coffee, tea, bananas, sugarcane, cacao Pineapple Vegetable crops, groundnuts, driest regions weet potatoes Cassava orghum ropical Forests ain Forest and easonal Forest > 1,000 mm, months Amazon basin, Congo basin, E Asia Close to equator ropical Forests ain Forest and easonal Forest > 1,000 mm, months Amazon basin, Congo basin, E Asia Close to equator Low land Forests ain forests - continuously wet mm common easonal forest - monsoon climate hort dry season, mm common emperate Forests - highlands ain forests - continuously wet mm common easonal forest - Monsoon climate hort dry season, mm common

4 Lowland ropical Forests (< 900 masl) Complex plant community 2-4 stories of trees 30 m) Bottom has herbs and shrubs if sufficient light Agriculture Most of nutrients in plants oil has poor fertility (especially rain forest) Difficult to clear land ropical Forests Cropping ystems hifting agriculture, traditional hade Agriculture Leave original trees to provide shade Coffee or Cacao cultivation Minimum of 20 years lash and Burn Burn all trees to plant crops Fertility decreases rapidly (3-4 years) 50 years to grow back ropical Forests Cropping ystems Intensive Agriculture emove original vegetation by machine Use fertilizers, pesticides, herbicides etc. Annual crop production, banana plantation Many centuries to regrow - best guess May regrow grassland and not trees Clear cutting Not known how long to regenerate Agriculture Potential of Forests Good Potential Moisture Good quantity and well distributed oil ain forest soils have poor fertility easonal forests have better fertility than rain forests Usually well drained Elevation Cooler so slower growth Lower yields than lowland regions Perennial: oil palm, cacao, coconut, banana, coffee Annuals: cassava, yams, sweet potatoes wamp formations Waterlogged or inundated most of the year Fresh water areas Location Borneo, umatra, Malaysia, Guyana oil = histosols Drained for use, may be too acid Crops Deep peat, pineapple Moderate peat, Oil palm, coconut, coffee, cacao ropical Highlands Altitudes of 1000 m to 3000 m As approach equator can develop higher altitudes emperature is cooler 5.6 C cooler for every 1000 m Crops grow slower Can grow temperate tree crops at high altitude Wide range of moisture conditions Forest to desert

5 Evergreen forest ropical Highlands 1250 to 2500 mm rain common horter trees with closed canopy More shrubs and herbaceous vegetation Good Agricultural Potential ain, reliable, moderated by clouds, mist, temp Excessive rain at harvest is a problem oils: fertile with good organic matter ropical Highlands Large areas Cleared, cultivated, grazed, burned eplaced by grassland ubtropical to temperate crops ea and coffee below 2100 m Potatoes, pyrethrum Farming ystems in ropical Climate- Vegetation Zones Vegetation # humid months Deserts 0 anching Dryland farming Irrigated farming ree and shrub cultivation Any Questions? emi-deserts 1 x hrubland steppes 1-4 xxx x x Dry savannas 4-6 xxx xx xx x savannas Humid forests 7-9 x xxx xxx xx xx xx xxx x = infrequent, xx = mod. frequent, xxx= widespread