Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore...
Transcript of Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore...
![Page 1: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/1.jpg)
1950
Coal 38%
Oil & Gas 58%
Hydro 5 %
1900
Coal73%
Wood 18%
Oil & Gas 9 %
Hydro<1%
2000
Coal 23%
Oil & Gas 63 %
Hydro 8 %
Alt3 %Nuc
3 %
1850
Wood91%
Coal 9%
After Miller 1975 & World Almanac 2004
1975
Coal18%
Oil & Gas 73%
Hydro 4 %
Nuc 3 %
Alt2 %
USA ENERGY
![Page 2: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/2.jpg)
DEFORESTATION & DESERTIFICATION IRREVERSIBLE LAND DEGRADATION Wood: Raw material; fuel (16 GJ/ton; 2/3 ton/yr ea) Should be a renewable resource; but non-renewable use patterns. => Habitat loss; CO2 increase; Rainfall perturbations
Hadley cells Control wind patterns, rainfall Geo. Hadley, 1735
ITCZ (Intertropical Convergence Zone) Equatorial belt of low pressures, => constant, wet, aseasonal climate
=> rising air, year round high rainfall, winds cancel, calm, no hurricanes High Pressure Belts ~ 30° N&S lat- => descending air, arid (adiabatic compression- e.g. Santa Anna winds, LA; also chinooks)
![Page 3: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/3.jpg)
NASA
NSA
NASA
3-Cell HadleyModel
![Page 4: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/4.jpg)
http://www.ldeo.columbia.edu/edu/dees/ees/climate/lectures/gen_circ/#index_Hadley_%20cell_1
![Page 5: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/5.jpg)
http://www.staff.amu.edu.pl/~zbzw/glob/glob8b.htm
![Page 6: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/6.jpg)
USGS
![Page 7: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/7.jpg)
Character of Tropical Rainforests Rainforests mostly equatorial, 10 x106 km2 7% of land (Earth's total land =148.8 x106 km2) 57% in Central & South America (e.g. Amazon 5 x 106 km2)
Plants & Animals: Enormous diversity ~35% of Earths biomass ~ 50% of species on Earth 100-300 tree species/ha => very hard for insect infestations to destroy forest Dense continuous canopy; very little understory; little litter
Soils High rainfall => High leaching of Na K P Ca Mg => red clay, laterite Al Fe oxides => Low fertility soil => Most nutrients within biota! (e.g. epiphytes = plants on plants)
Soil Profile 1" leaf litter 2-5" topsoil permeable, low nutrient, clay-sand substrate
![Page 8: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/8.jpg)
Eroded hillside in Amazoniaillustrating thin infertile soils NASA
![Page 9: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/9.jpg)
http://www.votawphotography.com/photo/Flowers/425-Tree%20with%20Epiphytes,%20Trinidad.jpg
Epiphytes “Air Plants”
![Page 10: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/10.jpg)
IMPACTS 1) ~150, 000 km2/y are destroyed. Lose ~15 km2 this class (1 hr) 1/2 of rainforests are already gone (up from 1/4 to 1/3 in old lecs) 2) Land Degradation- irreversible conversion of rainforest to grassy scrubland, profoundly lowering carrying capacity & biological productivity
3) Erosion, Recharge loss => Flooding, Landslides
4) Habitat Loss
5) Climate Change- Lower rainfall (in the Amazon, >1/2 rain from forest ET) Albedo Change, CO2 increase
6) Species Loss: 3-100/day lost! Total species estimated at ~107 to 108; only 106 known Lost Agricultural, Industrial & Pharmaceutical products Lost genetic engineering potential
see Meadows et al., 1992, p. 5, 65
![Page 11: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/11.jpg)
![Page 12: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/12.jpg)
Deforestation in Rondonia: 2000western Brazil NASA
![Page 13: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/13.jpg)
Deforestation in Rondonia: 2003NASA
![Page 14: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/14.jpg)
Deforestation in Rondonia: 2006NASA
![Page 15: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/15.jpg)
Deforestation in Rondonia: 2009NASA
![Page 16: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/16.jpg)
Deforestation in Rondonia: 2012NASA
![Page 17: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/17.jpg)
Deforestation in Rondonia: 2000NASA
![Page 18: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/18.jpg)
Caroline BrickellEPS 221 2012
Last of a Kind300 y-old
Botanical Gardens, Akuapem Hills, Ghana
![Page 19: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/19.jpg)
Causes of Deforestation
NEW CROPLAND Demand of growing population Slash & Burn Cultivation of Rainforest ("shifting cultivation")- get nutrient rich ash- can grow crops for 2-3 y, then gone
FUEL (heating & cooking)
LUMBER Logging
Mining, ranching
Short term planning
Ignorance & Waste
=> Non-renewable use pattern Surprising that the value of other forest products such as nuts, rubber, drugs, or orchids do not far outweigh lumber value.
![Page 20: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/20.jpg)
Burning of Amazon forest for grazing land NASA
![Page 21: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/21.jpg)
Burned clearing, Brazil http://www.nationalgeographic.com/eye/deforestation/effect.html
![Page 22: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/22.jpg)
www.ctkenterprises.com/ethnobiology/reddirt.jpg
Slash & Burn before planting Guadaloupe, French West Indes
![Page 23: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/23.jpg)
National Geographic 10/95Rwanda
![Page 24: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/24.jpg)
Red Cedar 800 y , Washington State www.nationalgeographic.com/eye/deforestation/effect.html
This is NOT “Harvesting” You harvest what you plant.
![Page 25: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/25.jpg)
Deforestation in USA: mostly 19th Century
Causes: Clearing, construction (homes, shipbuilding, RR, etc.), Fuel (charcoal; steam engines)
Pre colonial USA: = 50% forest 1850 = 25% 1870 = 15% 2000 = net reforestation? Calaveras Big Trees State Park 30’+ dia sequoia- cut down & bark stripped for display at county fairs
1810 Census Preface (Tench Cote) Our forests encumber a rich soil, an hundred or two hundred miles from the sea, and prevent its cultivation.
1880 Census Preface (Charles Sargent) “Forests perform….important duties in protecting the surface of the ground and in regulating and maintaining the flow of rivers”
Perlin 1989 (ISD 418 P47) page 356,360
![Page 26: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/26.jpg)
Giant Sequoia Calaveras Big Trees SP
Criss
![Page 27: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/27.jpg)
Giant Sequoia b. 600AD felled 1853
Criss
![Page 28: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/28.jpg)
John Muir (1890's) Environmentalist; Spiritual writings
Through all the wonderful, eventful centuries since Christ's time- and long before that- God cared for these trees, saved them from drought, disease, avalanches, and a thousand straining, leveling tempests and floods; but he cannot save them from fools- only Uncle Sam can do that. Campaigned for Yosemite NP (Teddy Roosevelt); Established Sierra Club USFS- Gifford Pinchot (multiple use- logging, mining, recreation…) Still: Each year the average American uses the equivalent of one large tree about
100 feet tall and 18 inches in diameter for his or her wood and paper needs. USA is world’s largest producer of forest products = 2x Brazil USA is 2nd largest exporter of raw timber UN p. 24
USDA (2015) The United States exported a record $9.7 billion of forest products in 2014. Among U.S. agricultural exports, only corn and soybeans had higher export values. Logs and Lumber Are Top Forest Product Exports https://www.fas.usda.gov/data/money-does-grow-trees-us-forest-product-exports-set-record
![Page 29: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/29.jpg)
Ponderosa PineBlair LakeMalakoff Digging SP
Criss
![Page 30: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/30.jpg)
Deforestation in Mssouri: clearcut by 1920
In 1880 to 1920, Missouri was a leading lumbering state Shortleaf pine gone by 1910 Whitetail deer extirpated by1930
Civilian Conservation Corps (CCC,1933 ff, FDR) reforestation, lookout towers, parks & trails
Today, the state of Missouri boasts more than 14 million acres of forest land. Forest products contribute $3B/yr to Missouri economy
Pioneer Forest: Sustainable Forestry Leo & Kay Drey Purchased then restored 150,000 clearcut acres, & finally donated
https://mdc.mo.gov/about-us/department-details/missouri-forest-facts http://www.ladfoundation.org/ StLPD
![Page 31: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/31.jpg)
Drylands 1/3 of the Earth's land surface, or 47.1 x 106 km2.
Geographic occurrence Descending limbs of atmospheric Hadley belts, ~ 30°N and 30°S, Zones of rain shadow (e.g. US Great Plains) Within continental interiors Africa=37%; Asia=33%; Australia=14%; => ∑ = 84% of total), Adjacent to cold ocean currents (e.g. Peru-Chile).
Plants & Soils Fragile environment Vegetation density adjusted to water availability. Evolutionary Mechanisms: Plants Grow far apart; Deep roots Small, hairy or waxy leaves Growth only during rainy season Water storage as in succulents; etc.
e.g. Palo Verde (photosynthetic branches) Creosote (waxy leaves) Yucca, Cactus; Joshua trees (spacing); larger plants near roads due to runoff...
![Page 32: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/32.jpg)
USGS
![Page 33: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/33.jpg)
Drylands 1/3 of the Earth's land surface, or 47.1 x 106 km2.
Geographic occurrence Descending limbs of atmospheric Hadley belts, ~ 30°N and 30°S, Zones of rain shadow (e.g. US Great Basin) Within continental interiors Africa=37%; Asia=33%; Australia=14%; => ∑ = 84% of total), Adjacent to cold ocean currents (e.g. Peru-Chile).
Plants & Soils Fragile environment Vegetation density carefully adjusted to water availability Plants grow far apart Deep roots Small, hairy or waxy leaves Growth only during rainy season Water storage as in succulents; etc.
e.g. Palo Verde (photosynthetic branches) Creosote (waxy leaves) Yucca, Cactus Joshua trees (spacing); larger plants near roads due to runoff...
![Page 34: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/34.jpg)
Sonoran Desert near Tucson, Az
USGS
![Page 35: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/35.jpg)
Joshua Treeshttp://www.arrakeen.ch/usamex/202%20%20Joshua%20Tree%20NP.jpg
![Page 36: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/36.jpg)
http://www.kayakplace.com/essay/gc/gc12-03.jpg
Barrel Cactus
![Page 37: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/37.jpg)
Creosote Bush
http://helios.bto.ed.ac.uk/bto/desbiome/larrea.htm
![Page 38: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/38.jpg)
http://helios.bto.ed.ac.uk/bto/desbiome/larrea.htmCreosote Bush
![Page 39: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/39.jpg)
https://c1.staticflickr.com/
Palo Verde tree
![Page 40: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/40.jpg)
DESERTIFICATION: Degradation of lands (esp. soils & vegetation) in dry areas, which in some cases leads to the development of desert-like conditions. Unlike drought, desertification entails a permanent decline in biological productivity.
Impacts:
Vegetation Degradation Reduction of cover; habitat loss Change to less productive types Change from good pasture plants to unpalatable types ID & CA star thistle Grasses => Succulents (fire resist.) & thorny shrubs (grazing resistant) Slow growing, long lived types => fast growing, short lived types
Soil degradation Erosion, Waterlogging followed by salinization or alkalinization Compaction
Serious global phenomenon: 60,000 km2/y irretrievably lost ~32 x 106 km2 seriously affected ~ 1/5 of Earth’s land area (cf. only 13 x 106 km2 of food producing land in world = 9%)
![Page 41: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/41.jpg)
Sahel ("edge of the desert") West Africa (Mali, Mauritania Niger, Chad, Sudan, etc);
Rainfall only 20-40 cm rain/yr (8 -16”/y) Drought since 1968, causing 100,000 to 250,000 deaths. Caused by human exploitation of lands.
Concept that the Sahara desert is advancing southward at 5.5 to 9 km/y is not accurate
Vegetation change from good pastures to unpalatable species.
![Page 42: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/42.jpg)
![Page 43: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/43.jpg)
Sahel, Chad
USGS
![Page 44: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/44.jpg)
Encroaching Saharan Dunes, Nouakchott, Mauritania USGS
![Page 45: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/45.jpg)
PRIMARY CAUSE OF DESERTIFICATION: Poor land use
Overcultivation Removal of cover; Decline in fertility & water-holding capacity of soil; Erosion; compaction
Overgrazing Compaction (trampling) Vegetative density reduction Erosion
Mismanagement of irrigated cropland & water: Poor drainage or overwatering lead to waterlogging, followed by crusting Salinization
Deforestation: Loss of vegetative cover Loss of soil cohesion (roots) Increased runoff & erosion
Climatic change (?) Little evidence that this is the major cause
![Page 46: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/46.jpg)
Overgrazing, Rio Puerto Basin, NM USGS
![Page 47: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/47.jpg)
FAO
![Page 48: Hydro USA ENERGY World Almanac 2004 - EPSc 221epsc221.wustl.edu/Lectures/221L30forests.pdfbefore that- God cared for these trees, saved them from drought, disease, avalanches, and](https://reader035.fdocuments.net/reader035/viewer/2022070803/5f02fb2c7e708231d406f47b/html5/thumbnails/48.jpg)
Cause differs from place to place- Australia animal overpopulation China human overpopulation USA overuse of groundwater Desertification may be reversible, sometimes even naturally if the stress factors are removed, but most often reversal is a matter of economics HISTORICAL PERSPECTIVE: Desertification is not new- but in the past the problem was regional. Now, the activities of the dense, globally distributed population has global-scale consequences. Plato (4th century BC) Our land, compared with what it was, is like a skeleton of a body wasted by disease.