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Conservation in the tropics and Prosopis: The allpurpose tree Paul R. Earl.
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Conservation in the tropics and Prosopis: The allpurpose treePaul R. Earl
Save the planet! OUR PLANET seems to be drying out, and water wars not so far off. The primary selection factor may become humidity. The planetary extremes have always been ice and sand, and resistance to desiccation is likely to soon involve the genetics of crop plants. Although the fight for food is perhaps more obvious than the one for water, both exhibit the Mathusian notion that geometrically increasing demand exceeds arithmetically increasing supply. Thus, overpopulation is accelerating.
Sensitive actions like deforestation are rapid and highly evident now, because of human overpopulation. The Brazilian disaster was forest fire for the benefit of the cattle industry. Almost everybody knows these things and does little about them, because they are not empowered to act positively. But also, the public likely does not understand the fragility of the ecology involved and even contributes to green groups embezzling money.
Education and public health and add development may well be poorly financed just because they are not given priority. This is true of research and also conservation. As we do not have the direct power to make changes, we shall suggest tropical legumes mainly for abandoned lands. Peter Felker of Texas demonstrated the applicability of mesquites to the lands they are found on.
How does Prosopis (mesquite) fit into rural development?The use of trees as windbreakers in arid lands is sufficient reason for promoting them. Mesquites sometimes grow where nothing else except cactuses can. However, the days when they formed productive hardwood forests are over. By desertification kindled by man, the days of trees over 100 years old are over, mostly.
The range for growth is governed by the relative humidity and temperature. When the air is dry, the stomata of the leaves close and photosynthesis stops. Then individual biomasses and new tree establishment are reduced. When the air is moist, other species of shrubs and trees will display successful plant composition.
“The rebellious sands are subdued and the inhospitable soils are colonized. The dreary scene of dry districts is changed to that of green belts. The bleak treeless landscape is painted with splashes of brown, green and yellow. The monotony is broken for the traveler and the sheep and goats munch and crunch happily on the proteinous pods. The rural folk, whose lands were getting buried under drifting sands are grateful to the Forester and Prosopis, and the poor folk who had no fuel to burn in their hearths now have Prosopis. They collect the fuel in their leisure and sell in towns for a descent price.”
The pod crop, browsing leaves and gathering fuel have been mentioned. Charcoal for cooking and fence posts and living fences along with fine furniture including rich parquet floors are attractive products. However, vegetation to stabilize landscapes might be the most important role for mesquites. The pod harvest might be better appreciated, and timber in all forms conserved and protected.
Foliar morphology. By eye, mesquites can only be told apart by their foliar morphometrics. Prosopis has species only in taxonomic dreams, since all or most cross.The illustration of the mesquite Prosopis glandulosa is for the description by John Torrey in 1828. Influourescences of over 200 individual flowers and pods are shown. The flowering parts of all mesquites are similar. Torrey’s mesquite is from Col. Long’s creek, Union County, New Mexico, USA
The biological species conceptdepends upon crossability. Regardless at present, the taxonomic species is more popular. This means that about 80 taxonomic species are taken as real, although 2-3 or even only one biological species exists (P. africana).
The 5 measures of the leaves are a) LL length of leaflet, b) LR length of rachis,c) PL number of pairs of leaflets, d) PR number of pairs of raches, ande) LP length of the petiole. LL, LR & LP are in mm, whereas PL & PR are counts. Either 1 or 2 PR are common, and the range is 1-4 PR. Four different races are shown in the illustration. Other morphological characters like has-or-has-not spines are almost worthless.
If and only if different mesquites are grown in a common garden can phenotypes and genotypes be distinguished. Mesquites have not been categorized into satisfactory species by any means including the polymerized chain reaction of DNA. Most of the mesquites of the Americas cross. Convergence is a large unresolved issue. When a niche in Chile is the same as one in Venezuela and another in Mexico, expect to find the same leaf design. Favored hybrids including mutants are fixed by the niche.
Some crosses of New World mesquites demonstrating the high crossability among Prosopis. Tiny is a new race from Sonora, Mexico.Similar leaf designs found far apart are fixed by their niches that are perhaps identical and do not necessarily have genes acquired from common descent. Does this sound like a Lamarckian argument?Plantations like natural woods can slow down soil erosion.
An ounce of prevention is worth a pound of cure. This will not hold when the damage is inevitable. Does this slogan relate to sustainability? Sustainability only applies to opulent countries. The harsh nature of the future ecology is being vastly underestimated. Removal of woods changes green to brown.
Then a mesquite plantation while approved as a step in the right direction may somewhat alleviate aridity but not cure it. The redistribution of water through evapotranspiration by shrubs and trees is an enormous benefit of this cover. The cover is sometimes accused of using up water that it is actually redistributed. Dimwitted people may believe that mesquite-occupied areas are adversely using all the water when the problem can be human population/water.
Prosopis microphylla, 15 m high, at Zumpango, Guerrera, Mexico beside a seasonally dry arroyo (stream). Maximum height of mesquite at Lago Chapala, Jalisco, Mexico is 22 m.
Summary. Standard commercial forestry does not consider mesquites since generally mesquite woods are exhaused by overuse. They, in Felker’s words, “just hold the world together.” Mesquites represent a vital part of the tropical world, because of their freatic ability to gather water through times of drought and store it. Storage means the shutdown of biomass production.
Summary (cont).They can grow a meter in height per year if they get the water. They provide browse, pod harvest and household fuel wood. Vast arid territories support silvopastoral systems. These lands cannot sensibly be converted to crop lands, and must produce at low levels. Although mesquite plantations may not be truely profitable, their value as windbreakers is high.
Summary (cont).A great problem is enormous destruction by bulldozer landclearing and fires. The common basis of desertification is the futile attempt to grow crops when the native vegetation cannot prosper. The final problem is how to give higher values to arid lands, while knowing that subsidies fail. Perhaps mesquite product development can extend beyond poverty, and improve the quality of life.
