Mean Seed Germination Data of P. Juliflora Inside Fenced Area
|Date of sowing||No. of seeds sown||Germination dates||Germination period in days||Depth of sowing|
|Mean ± SEm||a = 102.96 ± 10.07||0.28 N. sig.||2.67*|
|b = 98.92 ± 9.71|
|c = 68.0 ± 8.31||2.42*|
* Significant at 5% probability level.
In the unprotected area, seed germination was noticed from the fith day of sowing, but it was 21% in “a” and “b” treatments and 20% in “c” treatment within the first fortnight of sowing. Here, the seedlings remained under constant trampling by stray cattle, which prevented further scope of sprouting of the seedlings. At the end of thirty days, there were hardly any plants visible in any of these treatment areas due to biotic interferences, indicating thereby that unless proper protection is enforced, establishment of a P. juliflora plantation or of any other species would be a gamble in arid regions.
The study also revealed that raising of a plantation of P. juliflora is feasible from seedlings provided the area is protected from biotic interference.
The provenance trial of Prosopis juliflora indicated that seeds of Israel and Chile lines were superior to those from other sources, as evidenced by the growth attained over 7 years at Jodhpur and 3 years at Bikaner. The local Bikaner line performed equally well with 59% establishment, and 248.0 cm mean growth in height within a period of 3 years (Table 8).
Percentage Seedling Establishment and Growth in Height of P. juliflora of Different Provenances Tried at Jodhpur and Bikaner Research Farms
|Species||Source||Mean height (cm)||Establishment (%)|
To a certain extent, the author, after careful examination beneath the trees of P. juliflora in different habitats, has come to the conclusion that P. juliflora trees do encourage shrubs and grasses to thrive well under their canopies, wherever the trees have grown tall with straight stems. In case of short trees with drooping low branches, natural shrub/grass vegetation is poor or meagre due to the swinging and sweeping process of the low branches, which normally clean up the ground surface. Due to this mechanical action of the low branches, whatever seeds sprout are either damaged or swept away from the vicinity of such low branched trees. Under tall and straight stems, luxuriant growth of grasses, e.g. Cenchrus ciliaris and Aristida spp. has been observed on different habitats. Furthermore, selection of such straight types of Prosopis juliflora will also be suitable for silvopastoral programs.
Some scientists are of the opinion that P. juliflora, if raised on large scale, would become a weed in due course of time by spreading gradually through its seeds passed through the digestive system of sheep and goats in the form of droppings. It may be true, if this species is grown on wastelands where annual rainfalls exceeds over 500 mm and if the plantation is raised along river banks. In areas where rainfall is erratic, uncertain and varies between 250–350 mm, this species is a boon, as no other tree would grow well under such hard environmental conditions except Acacia tortilis. These conditions are often encountered within arid and semi-arid environments, and when the fuel wood requirements of local inhabitants is taken into account, preference for fast growing, drought-hardy tree species is needed. This species can hardly encroach upon the surrounding areas under the preventing inadequate moisture conditions of dry region soils. The palatability and chemical analyses of P. juliflora and P. cineraria leaves have been compared (Table 9).
Palatability and Chemical Analysis Data for Prosopis juliflora and Proposis cineraria
(The figures represent percentage of the constituents on dry weight basis)
|Palatability & chemical analysis||P. juliflora||P. cineraria|
|Crude protein (%)||21.4||13.9|
|Nitrogen free extract (%)||50.0||59.2|
Flowers produce nectar for good quality honey. Pods are eaten freely by livestock. Ripe pods are of high nutritive value, containing 12 to 13% crude protein and are rich in sugar and nitrogen. In Mexico, ripe pods are made into coarse flour and baked after removing the seeds, fermented and brewed into weak beer.
The wood is hard, durable and has good fuelwood value (8,050 Btu/lb). Good quality charcoal is obtained from the branches and main stem. It can produce about 100 kg fuelwood per tree in about 10-year rotations on sandy soils, with rainfall ranging from 300 to 400 mm per year. The tree exudes gum from the sapwood, which is used in industries like sizing of paper, calico printing, cosmetics, etc. If suitable utilization of this gum can be found in industries, it will enhance the value of this tree species (Ganguly and Kaul, 1961).
Pests and their control
In India, rodents and white ants are the main pest for seeds and seedlings of this species. Rodents eat up the tender cotyledons and the young seedlings in the initial stages. Rodents can also ruin older P. juliflora plantations by gnawing at the roots below ground level. This sort of destruction has been noticed at Udramsar (Bikaner), in cazri sand dune afforestation blocks. White ants are equally destructive to the younger as well as older plantations.
Unless their menace is properly and timely checked, all efforts to raise such plantations by direct sowing and transplanting would be futile. The precautions to be taken from rodents is by pre-baiting and destroying them with poison baits before sowing seeds or transplanting seedlings. White ants can be controlled by treating the planting pits with Aldrex 30 ec solution before transplanting seedlings and successively repeating twice at fortnightly intervals.
Prosopis juliflora and wildlife conservation
Prosopis juliflora thickets have become fairly dense in the low lying areas of Kharda, Tal Chapar and Guda Bishnoi. In these areas, population of black bucks, Antilope cervicapra is fairly dense due to protection given to them by the Bishnoi community. Along with black bucks, blue bulls or nilgai (Boselaphus tragocamanus) and Chinkaras or Indian gazelles (Gazella gazella), are also found in fair numbers. The pods of Prosopis juliflora provide highly nutritive diet to these wildlife communities, besides acting as a good shelter, protecting them from sun and strong desert winds. The sharp thorns of the trees, it is alleged, constitute a real hazard to the antelopes. However, in these areas we have never seen a limping black buck, blue bull or chinkara to prove that the thorns could be injurious to these wildlife species. On the contrary, we expect that P. juliflora thorns serve to spurn poachers with vehicles. Once the wild animal enters the P. juliflora thicket, it is safe as chasing by a vehicle is impossible and dangerous due to hazards to the vehicle tires. Nevertheless, there is a good scope of study regarding the relationship between P. juliflora and wildlife.
The author expresses his grateful thanks to Dr. K.A. Shankarnarayan, then Head of Plant Studies Division of this Institute, for his constant encouragement and guidance for preparing this monograph. I also take this opportunity to thank Shri. C.P. Bhimaya, former Director, and Sri R.N. Kaul, former Head of the Plant Studies Division of this Institute, for conducting and encouraging various studies on Prosopis juliflora. My grateful thanks are also due to all the staff members of the Silviculture Section for their assistance rendered thoughout.
bhimaya, c.p.; kaul, r.n. and gauguli, b.n., 1965: “Studies on the presprouted stumps of Prosopis juliflora,” Ann. Arid Zone, 4 (1): 4–9
bhimaya c.p.; jain, m.b.; kaul, r.n. and gauguli, b.n., 1967: “A study of age and habitat differences in the fuel yield of Prosopis juliflora,” Indian Forester 93 (6): 355–359.
ganguli b.n. and kaul r.n., 1961: “Gumosis in Prosopis juliflora,” Sci. and Cult. 27:489–490.
gupta r.k. and balara g.s., 1972: “Comparative studies on the germination, growth and seedling biomass,” Indian Forester 98(5).
kaul, r.n.; goswami, r.p. and chitnis b.k., 1964: “Growth attributes predicting for pod and seed yield of Prosopis specigera,” Sci. and Cult. 30 (6): 282–285.
kaul, r.n. and jain m.b., 1967: “Growth attributes and their relation to fuel yield in Prosopis cineraria,” For. Rev. 46: 2.
lahiri a.n. and gaur y.d., 1969: “The nature and role of germination inhibitors present in leaves of Prosopis juliflora,” Proceedings of the National Institute of Sciences of India, 35: 60–71.
muthana k.d., 1977: “Improved techniques for tree plantation in the arid zone,” Technical Bulletin No. 2, cazri, Jodhpur.
muthana, k.d. and arora, g.d., 1979: “Acacia tortilis (Forsk), a promising fast growing tree for Indian arid zones,” Technical Bulletin No. 5, cazri, Jodhpur.
vasavada p.k. and lakhani b.p., 1973: “A note for obtaining clean seeds of Prosopis juliflora from pods through chemico-mechanical methods,” Indian Forester, 99(3): 163–165.
Grassland and Pasture Crops Group, fao
The Republic of Niger is located between 11° 37' and 23° 23' north latitude. It is a landlocked country 1,200 km south of the Mediterranean; 1,900 km to the east of the Atlantic Ocean and 700 km north of the Gulf of Guinea. It is one of the hottest regions in the world, and 4/5 of the territory are located within the Sahara desert.
Rainfall varies considerably, from very low in the Sahara, to 870 mm in Gaya. However, the most important regions for the purpose of this paper are the Sahelian and Sudanese zones, with rainfall ranging from 250 mm to 450 mm; in some minor areas it can reach as much as 700 mm.
Agriculture is the main resource, with 90% of the population involved in rural activities; among these, livestock production is of great importance to the rural economy, with 4.5 million heads of cattle, 3.5 million sheep, 7.5 million goats and 400,000 camels. Most of the livestock population is to be found grazing natural grasslands at those regions below the 350-mm rainfall level, where agriculture is not practiced. In these regions fodder trees and shrubs contribute greatly to livestock diets, particularly during the dry season.
|Forest nursery for the Keita project's afforestation effort.|
Considering the afforestation programs in Niger, and in view of rainfall variability both in total amount and distribution, it is essential to count on a wide choice of species.
The following have been introduced: Azadirachta indica (Neem), Prosopis juliflora or spp., Parkinsonia aculeata, Eucalyptus camaldulensis, Cassia scamoa, Dalbergia sisso, Dononia regia (Flamboyant), Anacaadun occiderdalis, Cymelina arborea, Teck (Tectona grandis, Tamarix spp.).
Among the native species we find: Acacia albida (Gao), A. raddiana, A. senegal, A. seyal, A. scorpiodes var. adonsoni, Balanites aegiptiaca, Ziziphus mauritanai and Z. spina-christi, Banhinia rempescans, Sclerocaria biwa, Salvadora persica, Parkia biglobosa (Nere), Butyrospernum parkii (Karite), Tamarincus indica (Tamarinier).
Many of the above mentioned species have multiple uses and have been planted for such purposes as windbreaks, firewood production for village dwellers, erosion control and watershed management, fixing of dunes and recreation.
The Keita Valley Project
Among the more recent and important projects dealing with fodder trees, there is the Project on the Integrated Development of the Keita Valley, executed by the Food and Agriculture Organization of the United Nations (fao) with financial support from the Italian government.
The objective of the project is to carry out a number of operations, including reforestation, to reduce water deficits, curb water and wind erosion, and protect all soils actually or potentially apt for cultivation, thereby increasing overall production potential.
The project covers approximately 4,860 km2 of valleys, plateaux, hills, mountains, etc.
The region has been subject to sand dune enchroachment; this, coupled with the unlimited destruction of woody species used for firewood and excessive grazing, has led to total destruction of the agricultural potential of the valley.
|Women play a very important role in building defenses against wind erosion in Keita.|
Rainfall in the valley varies from 300 mm to 400 mm, falling between June and September. The vegetation is limited to few Combretum spp. and small Acacia spp.; there are no areas of forest or savanna. Agriculture is of a subsistence type (tomatoes, onions, sorghum, millet and sweet potato), as a result of the difficulties for cultivation.
The Keita project has, therefore, developed a strategy to reduce soil degradation which causes food shortages, leads to desertification and finally to a total exodus of the population.
During the duration of the project, the construction of 5,500 km stone-lined contour terraces is envisioned, as well as the establishment of 5,000 ha of windbreaks; 5,000 ha of village forests; control of 10,000 ha of dunes and protection of 20,000 ha of natural forests.
During 1985 approximately 360,000 seedlings were raised and planted, with 85% success. In 1986 the figure was increased to 1.1 million, of which 220,000 were Prosopis juliflora; the other species included are: Acacia nilotica, A. seyal, A. raddiana, A. senegal, A. albida, Balanites aegyptia, Tamarix orientalis, Ziziphus mauritania, Leucaena leucocephala, Acacia auriculiformis, Banhinia rempescans, Prospis juliflora, Parkinsonia aculeata, Mocixyu, Eucalyptus, Cassia siberiana.
These species have been planted close to the stone-lined contour terraces on the hill slopes, using different systems, leading to increased water accumulation.
The project is expected to double its planting rate and develop improved systems for the utilization of these trees, in particular fodder trees.
The local population is already motivated to continue planting trees and keeping the contour terraces in good condition. The results are therefore anticipated to be most effective, allowing the village population to remain in the rural areas in view of the increased and sustained productivity of their lands, consequently avoiding emigration to urban areas. The role of Prosopis juliflora with its multiple use is of major relevance in this regard.
Present Situation and Development Prospects
Ph. D., Arid Zone Institute
The marginal lands cover in Tunisia near 87,200 km2, of which 7,200 km2 correspond to humid and semi-arid bioclimatic stretches. The rest, about 80,000 km2, are accounted for by arid and subdesert zones.
The first type of marginal lands (8% to 9% of the total) is covered essentially by deciduous oaks (Quercus faginea, Quercus afares); cork oak (Q. suber), green oak (Q. ilex), Aleppo pine (Pinus halepensis), thuja (Tetraclinis articulata), carob (Cerotonia siliqua), mastic tree (Pistacia lentiscus) and oleaster (Olea europea).
The second type (91% of the total) is generaly steppe, the following types of which can be made out:
The establishment of large fodder reserves based on woody species is a constant interest of Tunisia's agro-pastoral policy, with a double objective:
Fodder reserves, up to the present established at random throughout the Tunisian territory, are mainly made up of Acacia cyanophylla, A. ligulata and Atriplex.
Prosopis, after several trials, is gaining an increasingly important position along these species.
(according to Pottier-Alapetite)
The genus Prosopis is scantily represented in Northern Africa. In Tunisia, only one spontaneous species was found and described in “Flore de la Tunisie” by Pottier-Alapetite (1979). It was Prosopis stephaniana (M.B.) Kunth, a sparsely thorny shrub not more than 1 m high, with bipinnate leaves made up of 3 to 5 pairs of petioles, each with 8 to 12 pairs of oblong folioles. The cylindrical-shaped flowers are grouped in small yellowish axillary bunches; the ovoid blackish pods are 3 cm/1.5 cm long (see Figure).
Prosopis stephaniana occurs almost solely on sandy ravines in the arid and semi-arid bioclimatic zones.
Many species of Prosopis have been introduced to Tunisia and tried at different locations in the North, Center and South of the country. According to Le Houerou and Pontanier (1985), the most noteworthy species are the following:
|Prosopis juliflora Swartz||Central America, Caribbean|
|P. laevigata (Humb et Bonpl. ex. Wild) mc Johnston = P. dulcis Kunth||Mexican high plateaux|
|P. glandulosa (Torey)||Southern u.s.a.|
|P. velutina Wooton||Mexico, Southern u.s.a..|
|P. chilensis (Molina Stun. in Burkart)||Andean countries|
|P. cineraria (L.) Druce||India, Pakistan, Persian Gulf|
|P. tamarugo F. Philippii||Chile|
The older plantations were restricted almost exclusively to arboreta, where performance trials were conducted with forest and pasture species from several provenances; these arboreta are spread throughout Tunisia, the most relevant being the following:
Among all the introduced species, Prosopis juliflora, P. laevigata and P. glandulosa appear to give the best results. They are, however, difficult to differentiate and this lends itself, at times to confusion, derived by the similitude between their morphologic characteristics and their remarkable polymorphism (Burkart, 1976).
Apart from the characteristics intrinsic to each species, temperature, edaphic conditions and moisture are the principal external natural factors that seem to condition the development of prosopis.
Except for P. juliflora and P. chilensis, which resent cold and require for their development an average temperature of over 2° C during the coldest month, the other species of Prosopis can tolerat much lower temperatures. It may be stated, then, that with the exception of the central-western strip (Makthar, the Sers, Tala, Kasserine, Feriana, etc.), which have a cooler climate, temperature does not pose a constraint to development of the genus Prosopis in Tunisia.
b. Edaphic Requirements
The edaphic requirements of the Prosopis species introduced are well known; their development is more or less linked to light deep soils, but they can adapt to poor, sandy or even stony soils, where they take on a shrubby outlook. Presence of salt does not seem to impair their development. Healthy individuals have been observed thriving on salty or gypsum soils.
The Prosopis species introduced in Tunisia and, particularly, P. juliflora, have a reputation for being little demanding as regards water, and can thrive with annual rainfall as low as 150 mm. According to Dahl (1982), Prosopis are phreatophytes with a root system, of mixed type, able to tap moisture as deep as 15 m into the soil. This accounts for their remarkable rusticity and for the success of some of the species introduced, both in the northern and central parts of the country, that are relatively moist, and in the very dry deep south.
The plantation trials carried out in the Central Tunisian areas (Kairouan, Sfax) do not seem conclusive; the P. juliflora and P. laevigata individuals have shown scant development. Its very low germination rates have made P. tamarugo introduction trials fail until now.
Although established in very dry areas, introduction trials with P. juliflora, P. laevigata and P. cineraria in the regions of Houmt Souk, Jerba, Ben Gardane, Sidi Maklhouf and El Fjé, Médinine and Kébili have shown relatively good success. The essential factor behind this good performance is the presence of a low-depth water table; soils here are generally calcareous, saline or contain gypsum, are sandy or sandy-loamy.
Numerous authors have conducted research on the utilization possibilities for Prosopis and on their potential production. The biomass studies carried out by Lepape (1980) in 14-year-old P. juliflora plantations show the woody mass to be on average 50 ton/ha; pod output, expressed as dry matter, ranges from 250 to 400 kg/ha/year. This corresponds to a carrying capacity of 0.6 to 0.8 sheep/ha. The only disadvantage seems to be the leaves, that are scarcely palatable to livestock.
The numerous introduction trials with Prosopis in Tunisia and, particularly, P. juliflora, P. laevigata and P. glandulosa, are encouraging.
Large-scale planting with these species is foreseen. In addition to their fodder and timber production capabilities, of being able to resist the harsh conditions prevailing in arid and sub-desert areas, these species are expected to play an important role in checking the silting processes and in stabilizing dunes. These species can also play a role in raising the value of saline areas, particularly at the coastal strip, where the water table is near the surface.
Nevertheless, it is very important, before any large-scale propagation action is undertaken, to know very well the requirements, potential and, most of all, the ecologic impact of such an effort. A critical study of the findings arrived at in this field must be conducted. In this regard, it is necessary to take into consideration the biologic balance and environment of each species in its natural range.
It is also necessary to plan the diversification of plantations, trying other species, such as Parkinsonia aculeata, much more drought hardy than the most rustic Prosopis species.
A special effort must be directed towards studying the production potential of spontaneous Prosopis species and their possibilities of spreading.
burkart, a., 1976: “A monograph of forage shrubs in the Norte Chico region of Chile,” In; Browse in Africa, Le Houerou, H. N. (ed.), ilca Addis Abeba, pp. 299–302.
dahl, b. e., 1982: “Mesquite as Range Plant,” In: Mesquite utilization proceedings, Symposium, parker, h. w. (Ed.), Texas, Tech. Univ., Lubbok, pp. 1–20.
le houerou, h. n. and pontanier, r., 1985: “Evaluation des plantations sylvo-pastorales dans la zone aride de Tunisie,” Rapport de Mission uneco dans le cadre du Projet FP/6202-85-03 (2578),” Pilot Project for Curbing Desertification in the Tunisian South, mimeographed, 70 p.
lepape, m. c., 1980: “Apercu sur les fourrages ligneux des Iles du Cap Vert,” In: Fourrages ligneux en Afrique, Le houerou, h. n., (Ed.), Etat actuel des connaisances. Coll sur les fourrages ligneux en Afrique, Addis Abeba.
pottier-alapetite, g., 1979: “Flore de la Tunisie”, First Part, Publications scientifiques tunisiennes, 651 p.
Lorenzo J. Maldonado
Engineer, Director, Northeast Forestry Research Center
The Republic of Mexico is located in North America, between latitudes 32° 43' N and 14° 32' N, and longitudes 86° 42' W and 118° 22' W.
The country covers a total of 1,958,201 km2, with the continental portion accounting for 1,953,128 km2 and insular territories for the remaining 5,043 km2.
The Mexican territory is made up of a flatland system structured by six large mountain ranges, with altitudes ranging from sea level at the Gulf of Mexico and Pacific coasts, to 5,610 m at the Orizaba peak in the State of Veracruz.
This varied altitude, the fact of striding the Tropic of Cancer and the oceanic influence facilitated by its narrow continental mass are factors giving rise to a great diversity of climates, where temperatures as low as —29° C and as high as 59° C have been recorded in different regions. Annual rainfall ranges from 5,179 mm in some areas to 22.3 mm in dry regions. The continental area breaks down by type of climate into 4.8% with warm humid climate; 23% with warm subhumid climate; 23.1% with temperate climate; 28.3% with dry climate and 20.8% with very dry climate.
At present, Mexico has 4,841,216 ha under irrigation and 18,297,199 ha of unwatered croplands.
The above factors give rise to a greatly complex plant cover, as practically every large biome classified in the world is present here, such as jungles, forests, shrubland and thickets, grasslands and other plant communities, such as high mountain meadows, aquatic vegetation, hallophytes, etc.
This plant cover diversity is not solely due to the geomorphologic and climatologic features mentioned above, but also to the fact that the Mexican territory has South American, North American and Eurasian vegetation, and some unique biomes probably native to this land.
For these reasons, the present distribution patterns for the Prosopis species do not rule out the possibility of an ancestral desert flora common to the whole of the American continent, which later split into two centers; the Mexican-Texan one, and the Argentine-Paraguayan-Chilean one, where most species of the genus Prosopis occur. There is endemism in both centers, a fact pointing to their antiquity. This suggests that dispersal of the genus over such long distances played a secondary role.
|Mexico's vegetation groups.|
Adequate use of renewable natural resources is one of the greatest concerns of man. This calls for in-depth knowledge of each and every resource, analyzing and focusing on the problems derived from resource management and conservation.
The genus Prosopis is considered an important resource in many parts of Mexico, and it is characteristic in arid and semi-arid landscapes.
The first references regarding this genus in Mexico come from Hernández, in 1651. Later on, Father Solís described the presence of Prosopis while visiting the missions located in the northern reaches of Nueva España, as Mexico was then known. It was also mentioned in 1789 by Clavigero, in his study of the Californian flora.
Most of the Prosopis species in Mexico are known by the name of “mezquite” (English “mesquite”), a hispanicized word derived from the Nahuatl “mizquitl”, meaning “bark that tans”. Curiously, the name of the genus Prosopis comes from old Greek, and is related to the tanning properties of its bark, used in the preparation of sheep skins.
In Mexico it is also known by the names of “guisache,” “chucata”, “tziritzequa” and “algarroba”.
In most arid regions, Prosopis plants occur as shrubs and only where adequate water supply is available they grow up to tree size. They develop better in river banks and on deep-soil valleys with high water tables. Occasionally, Prosopis is the most ubiquitous plant in many kilometers around, forming veritable forests known in Mexico as “mezquitales”.
Prosopis in Mexico presents some problems regarding nomenclature, as its taxonomy has not yet been conclusively defined. It is necessary to conduct cytological, genetic, biochemical and ecological research in this regard. Determination of this plant is further complicated by its considerable polymorphism resulting from environmental conditions and from natural crossbreeding among populations. This process is facilitated by its great genetic plasticity. However, eight species and three varieties can be distinguished, each presenting specific characteristics. The range of these species is outlined below:
Prosopis juliflora: Occurs in vast areas of the country, including the Baja California peninsula. It occurs in flatlands, mountain slopes and alongside streams and brooks. The name of the species refers to “julus”, or whip-like inflorescence.
Prosopis juliflora var. glandulosa: Occurs throughout Mexico, particularly in the southern areas but reaching all the way to the southeastern United States. It thrives on neutral and alcaline soils with annual rainfall varying from 150 mm to 750 mm, and at altitudes up to 1,500 m above sea level. The name derives from the connectival glandular anthers of its flowers.
Prosopis juliflora var. velutina: Occurs in Northeastern Mexico, in the State of Sonora. It grows in alluvial plains, in lower coastal strips and along desert streams.
Prosopis juliflora var. torreyana: Widely distributed throughout Mexico, particularly in the coastal plains.
Prosopis pubescens: Occurs in northern Mexico, the State of Baja California, part of Chihuahua and in Sonora. It grows alongside stream banks, in lowlands and near water tables. The name of the species derives from the downy quality of the fruit.
Prosopis reptans: Distributed in the Baja California Peninsula and in Northeastern Mexico. “Reptans” means “creeping”, a growth habit of this plant.
Prosopis cinerascens: Found mainly on the coastal area of the Gulf of Mexico, in alluvial soils with presence of a calcium carbonate induration stratum in the profile.
Prosopis palmeri: Occurs mainly at the Baja California peninsula. It grows mostly in or near dry riverbeds, in canyons and desert beaches.
Prosopis articulata: Distributed over a limited area near Guaymas, Sonora, and in the states of Tamaulipas and Veracruz. It grows on rocky plateaux and in plains along the Baja California peninsula.
Prosopis laevigata: Found mainly at the Central High Plateaux of Northern Mexico, the lower reaches of Tamaulipas and in parts of Oaxaca, Morelos, Puebla and Chiapas. It grows on hill slopes, depressions and flooded plains.
Prosopis tamaulipana: Occurs on the eastern portion of the Eastern Sierra Madre, in the States of Tamaulipas and Veracruz. It grows on heavy clay soils at low altitudes.
Table 1 shows the main morphologic and taxonomic characteristics of these eight species and three varieties.
Main Characteristics of the Prosopis Species in Mexico
|Thorn origin||Thorn length|
|Pinna length||Foliole Pairs||Foliole shape||Foliole size||Inflorescence length|
|Inflorescence shape||Inflorescence color||Pod shape||Pod length|
|P. juliflora (Swartz) D.C.||6 –12||Axillary||0.5–5||1–4||8–18||10–16||Elliptic oblong||6–23 × 1.6–5.5||7–15||Cylindrical||White-greenish||Flattened and straight curved at opex||8–29||9–17|
|P. juliflora var. glandulosa (Torr) Cockerell||7 –13||Axillary||1 –4.5||1–2||6 –17||6–17||Linear||30–45||5–14||Cluster||White-greenish||Linear flat||10–20||10|
|P. juliflora var. velutina (Woof.) Sarg||2 – 6||Axillary||1 –4.5||1–3||2 – 9||12–30||Oblong||4–6.4||5–15||Spike||White-greenish||Linear almost straight||8–16||6–10|
|P. juliflora var torreyana (L.) Benson||2 – 8||Axillary||1 –4.5||1–3||6 –17||6–13||Linear||15-2.5||5–14||Spike||White greenish||Linear almost straight||10–20||10|
|P. pubescens Benth||2 –10||Stipular||5 –8||1–2||2 – 3||4– 9||Oblong elliptic or oblong obtuse||20–50 × 6–10||5–8||Spike||Yellow||Spiral||8–24||8–10|
|P. reptans Benth||5 – 8||Axillary||4 –9||1||5 – 9||16–24||Linear Oblong||5–12 × 1.5–2.2||0.5–1.5||Round ball||Yellow||Spiral||5||7|
|P. cinerascens A. Gray||30||Axillary||1 –2||1–2||4 – 6||8–12||Oblong||1.5–3||2–4||Cluster||Yellow||Straight scythe-shaped||1.5–4||5–8|
|P. palmeri S. Wats||1.2– 6||Stipular||0.5–3.5||1||2 – 3||3–10||Glabrous and oblong elliptic||1.5–3||3.5–6||Spike||Yellow||Straight scythe-shaped||4–9||8–10|
|P. articulata S. Wats||2 – 5||Axillary||0.3–3||1||0.4–6.5||6–20||Linear elliptic||2.5–12 × 1.2–3.5||4–9||Cluster||Yellow||Linear but very flat||1–2.4||5–8|
|P. laevigata (Numb y Bonpl. Ex Willd) M.C. Johston||2 – 7||Axillary||1 –3||1–2||2.5–12||20–30||Elliptic oblong||5–10||4–10||Cluster||White greenish||Linear, glabrous straight or slightly curved||9–17||7–14|
|P. tamaulipana Burkart||6 – 8||Axillary||0.5–1.5||1–3||2.5– 4||15–29||Oblong obtuse||2.8–6 × 1–1.8||5–8||Cluster||White greenish||Straight||8–13||6–8|
P. juliflora in Mexico
In arid and semi-arid zones of Mexico, Prosopis is one of the most conspicuous genera in the plant cover and the species juliflora the most ubiquitous, for which reason this work will focus mainly on this species, considering its traditional, potential and actual uses.
The wood of P. juliflora has a specific base of 0.76 and has an excellent calorific value of some 17,000 Joules/kg, thereby making it popular as firewood, mainly for cooking and heating purposes. It makes good charcoal and charcoal briquettes. These two fuel items are widely used in barbecues, a typical way of roasting meat in Northern Mexico.
The timber is also used for making railroad sleepers, furniture and parquet flooring. Its grain makes it an appreciated wood for handicrafts.
Another use of P. juliflora wood is the ellaboration of structural ribs for small boats. It is also used for making shoe blocks for the shoe industry and as insulator in high voltage power lines.
Stems and limbs provide poles and fence stakes, and are used as construction material. Some authors state that its durability ranges from 75 to over 100 years.
P. juliflora trees are used for providing some shade to cattle herds. The species has also been employed for over a century for binding shifting sand dunes.
Its flower is a source of nectar for bee-honey; apiculture is an economically important activity in this country.
P. juliflora pods are used for feeding bovine, caprine, ovine, equine and porcine livestock, being also eaten by wild animals, such as deer, coyotes, squirrels and many birds. They are used in different concentrations for dairy and beef cattle offspring rations.
It can also be industrialized through fast dehydration and milling, producing a very fine flour consumed by arid and semi-arid area inhabitants of Mexico, in products known by the local names of “mezquitamal,” “mezquiteatole,” and “pinole,” or as fermented beverages. Fruit extract and leaf ferment show strong antibacterial activity against Staphylococcus aureus and Escherichia coli. The juice of new leaves is used for treating certain eye ailments.
P. juliflora bark produces tannins used in tannery, and an infusion made therefrom has vomiting laxative properties.
The fibrous root is soaked in water and used for making strings which can be woven into rough fabrics. Dry roots make excellent kindling material, on account of their high calorific value. The plant fixes nitrogen, higher nitrogen contents having been detected in plants growing in the shade of P. juliflora.
The gum secreted by P. juliflora is used as replacement for gum arabic, with a wide range of industrial uses and also as adhesive in carpentry. From the ethno-botanic viewpoint, it shows medicinal properties, in particular for treating pharyngeal ailments, dissentery and to strengthen teeth.
Its physiognomic characteristics and ready environmental adaptation have gained it good acceptance for urban ornament in dry-region cities, alongside streets, in parks and gardens and in the Roughs of golf courses.
|Prosopis is a characteristic plant resource of Mexico's arid zones.|
|Its specific base grants P. juliflora excellent calorific value.|
|P. juliflora has outstanding qualities for utilization in multiple-use systems.|
|Prosopis gum has a wide range of industrial applications.|
P. juliflora has received strong impact through history in Mexico, depending on the ethnic uses it has been subjected to. At present, the following annual volumes are processed:
In the above figures, P. juliflora use for household purposes has not been considered. Furthermore, an additional 40,000 tons are estimated to be consumed annually as fodder and concentrated feed for different kinds of livestock. Reliable statistics for this are not available.
Although the genus Prosopis is very abundant in vast ecologic regions of the country, it has been little studied. Probably the abundance itself of the resource has conspired against granting it the relevance it deserves in Mexico's economic and social development, bringing about in turn a somewhat wasteful use of the resource.
The above starts from the lack of appropriate nomenclature, derived from the scant research studies on its taxonomy. At present, strong contradictions exist among pasture managers regarding its qualities as fodder producer, interspecific competition with grasses, and other criteria.
However, a certain amount of data on the species has been gathered since the turn of the century. For instance, Fortum recommended P. juliflora pods as fodder for livestock as early as 1911, basing on an analysis of the pod nutrient makeup. In 1933, Hernández rated P. juliflora as fodder plant and thought it advisable to store the pods and make efforts to cultivate the tree. Ramírez, in 1937. remarked on the importance of Prosopis cultivation at the Mezquital Valley. Rivera, in 1934, reported on the medicinal properties of P. juliflora. In 1947, Batalla considered the uses of its timber, of its bark for tannery and of its gum. That same year, Martínez recommended its cultivation in poor areas with temperate climate. Garza and Narváez showed the economic advantages of feeding livestock with P. juliflora. Borja, that same year, mentioned the economic importance of P. juliflora in forestry, livestock and farming activities. González, in 1964, considered that further applications must be sought for the plant. Marroquín et al. remarked in 1965 on the importance of this species for maintaining ecologic balance.
|P. juliflora pods are used as a source of fodder for livestock.|
Since the beginning of this decade, research on Prosopis has increased greatly in Mexico, in recognition of the high economic relevance of this species.
Furthermore, on August 23, 1985, the Official Research Institutes for Agriculture, Livestock and Forestry were integrated into one agency subordinated to the Agriculture and Hydraulic Resources Department, and named Instituto Nacional de Investigaciones Forestales y Agropecuarias (inifap, National Forestry, Agriculture and Livestock Research Institute). This reorganization permitted the interaction of specialists in various disciplines and brought about the concept of “multiple use of renewable natural resources.” P. juliflora is considered as a suitable species for inclusion in integrated production systems.
Mexico has developed methods for the following aspects concerning the genus Prosopis: germplasm collection, management and storage; reproduction methods; firewood production tables; efficient inventory methods; actual and potential use assessment; managament of natural populations; ecotype tests; progeny trials; market and marketing; urban plantings; windbreaks; wood characteristics; charcoal production systems; development of industrial technology for production of perfumes, tannins, fodder, etc.
From the above, it is evident that P. juliflora in Mexico is particularly suitable for being included in a multiple use model. Production systems must be sought which harmonize the exploitation of its natural populations, through programs aimed at its preservation and improvement, as it is a resource suitable for boosting economic development not only of arid lands in Mexico, but throughout the world.
Man-made Prosopis forest.
anonimo, 1980: “Vademecum Forestal Mexicano,” Dirección General de Información y Sistemas Forestales, sarh, México, d.f.
anonimo, 1984: “Anuario de Estadísticas Estatales,” Geografía e Información, Secretaría de Programación y Presupuesto, México, d.f.
anonimo, 1984: “Agenda Estadística 1984,” Instituto de Estadística e Informática, Secretaría de Programación y Presupuesto, México, d.f.
beltran, e. et al., 1964: “Las zonas áridas del centro y noreste de México y el aprovechamiento de sus recursos,” Ediciones del Instituto Mexicano de Recursos Naturales Renovables, a.c., Mexico, d.f., 186 p.
davila, a.h., 1982: “La distribución de mezquite en México,” Memoria de la Segunda Reunión Nacional sobre Ecología, Manejo y Domesticación de las Plantas Utiles del Desierto, Special Publication No. 43, inif, Mexico, pp. 135–138.
espejel, c.i., 1980: “Técnicas para muestrear y medir la producción de goma de mezquite,” Arid Land Resource Inventories, usda Forest Service, General Tecnical Report WO-28, La Paz, Mexico, pp. 451–454.
felger, r. j. et al., 1980: “Inventorying the world's arid lands for new crops: A model from Sonoran Desert,” Arid Land Resources Inventories, usda, Forest Service, General Tecnical Report wo-28, La Paz, Mexico, pp. 106–116.
ffolliott, p. and thames, j., 1983: “Manual sobre Taxonomía de Prosopis en México, Perú y Chile,” fao, Rome, 35 p.
gomez, l.f., 1970: “Importancia económica de los mezquites (Prosopis spp.) en algunos estados de la República Mexicana,” Mezquites y Huizaches, imernar, a.c., Mexico, d.f., pp. 1–70.
goor, a. and barney, c.w., 1976: “Forest tree planting in arid zones,” 2nd Ed., The Ronald Press Company, New York, pp. 353–477.
maldonado, a.l.j., 1980: “Clasificación dé tipos de vegetación de zonas áridas y semiáridas de México,” Arid Lands Resource Inventories, La Paz, Mexico, pp. 167–176.
maldonado, a. l.j. 1982: “Las especies ornamentales de la ciudad de Monterrey,” N.L., Memoria de la Segunda Reunión Nacional sobre Ecología, Manejo y Domesticación de las Plantas Utiles del Desierto, Special Publication No. 43, inif, Mexico, pp. 111–112.
maldonado, a.l.j., 1984: “Manejo de la cubierta vegetal en zonas áridas,” Mesa Redonda Internacional sobre Prosopis tamarugo Phil., Arica, Chile, pp. 151–168.
maldonado, a.l.j., 1985: “Sistemas de producción forestal de zonas áridas (experiencia en Latinoamérica),” Bol. Div. No. 72, inif, Mexico, d.f., 55 p.
ortega, r. s., 1982: “Especies maderables de zonas áridas,” Memoria de la Segunda Reunión sobre Ecología, Manejo y Domesticación de las Plantas Utiles del Desierto, Special Publication No. 43, inif, Mexico, pp. 131–35.
pardos, k.a., 1984: “Un programa de mejoramiento genético en Prosopis tamarugo y Prosopis chilensis,” Documento de Trabajo No. 1, conaf/fao, Santiago de Chile, 28 p.
signoret, p.j., 1970: “Datos sobre algunas características ecológicas del Mezquite (Prosopis laevigata) y su aprovechamiento en el Valle de Mezquital,” Mezquites y Huizaches, imernar, a.c., México, d.f., pp. 71–146.
standley, p.c., 1961: “Trees and shrubs of Mexico,” Smithsonian Institution, Washington, d.f.
vines, r., 1960: “Trees, Shrubs and Woddy Vines of the Southwest,” University of Texas Press, Austin, Texas, u.s.a.
Abdel Rasoul Fadel Mula Mustafa
Silviculturist, Forestry Research Section
Agricultural Research Corporation
P. O. Box 126, Medani, Sudan
According to estimates derived from maps produced by Meigs (1953), about 11% of the earth's surface is classified according to dryness ratio into arid and semi-arid. This amounts to some 2,177 million hectares as arid and 2,017 million hectares as semi-arid (Peterson, 1969). The arid and semi-arid lands in the Sudan are estimated to be 134.4 million hectares (Musnad, 1971). It is also estimated that the desertification process is progressing from north to south at a rate of five kilometers/year. This can be reversed by taking advantage of the variations in woody plants. Potentially important among these appear to be the genus Prosopis, particulary Prosopis chilensis (Molina) Stuntz.
Sudan's Dry Zone (< 400 mm)
Greater variations in rainfall both spatially and temporally are encountered in the short rainy season. The intense evaporation is accelerated by high temperature and high wind speed. These factors, added to the high and increasing animal population and marginal agriculture, led to devastation of the ground vegetation, with the result of desertification and its consequences.
The problems of Sudan's dry zone can be briefly summarized as follows:
Introduction of Prosopis in the Sudan
Prosopis is represented in the local flora by Prosopis africana syn. Prosopis oblonga Benth, which is distributed throughout central and southern Sudan and used in carpentry. It was first introduced under the name of Prosopis juliflora, corrected later to Prosopis chilensis. In 1979–81 under the Prosopis Project sponsored by idrc, 63 accessions were introduced for adaptability testing with the aims of fuelwood production, pods for fodder and soil stabilization. These accessions were grouped under the following species: Prosopis chilensis, P. glandulosa, P. juliflora, P. alba, P. velutina, P. specigera, P. nigra, P. fercta, P. pallida, P. articulata, P. pubescens and P. tamarugo. They were introduced from various areas of North America, Chile, Mexico, Argentina, India, Pakistan, Palestine and Kenya (for further details see Prosopis Project, Phase I: 1979–83, Final Report, Sudan, frc, p.o. Box 658).
These accessions were planted together with the previously introduced P. chilensis in different locations in Sudan's dry zone representing clay soil, sandy soil and gardud (sandy-loam soil with a crust-surface layer which encourages water run-off). Rainfall at these locations varies between 50 mm in the north and 250 mm in the south. The conclusions drawn recommended Prosopis chilensis as one of the most successful species in terms of shoot height and survival.
Prosopis chilensis (Molina) Stuntz
As already stated, when it was first introduced, Prosopis chilensis was mistaken for P. juliflora (Schwartz) DC, but then Abdel Bari (1986) studied its major botanical characteristics and compared them with those of the recently introduced accessions planted in Soba. She found that the original tree —introduced in 1917 from Egypt and South Africa—, as well as subsequent naturalizations by various experimental or incidental plantations, corresponded to P. chilensis (Molina) Stuntz.
Natural spreading and artificial regeneration
After its first establishment at Shambat in 1917, it was planted in Khartoum, White Nile, Nile and Kassala Provinces in small plots, either for research or protection. From these plots it spread naturally in the surrounding area on sites inundated annually and on water-catchment areas. Its spreading on these sites was aided by the presence of grazing animals, mainly goats. Seeds ingested by animals and contained in droppings germinate readily (El Hori, 1982). The growth of the resulting seedlings was favored by the conditions prevailing at the sites mentioned.
Ballal (1986), in his studies on Prosopis chilensis seed treatments, recommended concentrated sulphuric acid (60%) or mechanical scarification as the best presowing treatments, since they gave the highest germination rate (97.5%). This may be adopted in afforestation programs if the treated seeds are broadcasted on on-flow sites. On off-flow sites, planting with seedlings is advantageous since it evades the most vulnerable stage of growth, i.e. germination and early seedling growth. Seedlings are adequately taken care of during this critical period if they are raised in a nursery. Abdel Rasoul (1986) investigated the plantable size of Prosopis chilensis seedlings and recommended seedlings with the following characteristics:
These seedlings were obtained under conditions of open sunlight, in transparent polythene bags of 20 × 10 × 0.15 cm when empty. The bags were filled with 100% clay, 100% silt or 50%–50% clay/sand, depending on soil availability, then watered every three days in the morning. The seedlings should stay in the nursery for 11–14 weeks and then planted out at the ridges in clay sites and in saucer pits in gardud sites.
During the long dry season (9 months), the large animal populations depend on the perennial vegetation. This plant cover is often deteriorated and overgrazed, leading to desertification particularly around water sources. Growing of Prosopis chilensis in this dry zone should meet the feeding requirements of these animals, apart from preserving the environment. Its green vegetative parts are unpalatable but the pods are much favored by animals, forming an adequate maintenance ration for goats and sheep (Abdel Gabbar, 1986).
Ballal (1986), in his study on Prosopis chilensis phenology, found that the pod production season starts in December and ends in June. This coincides with the dry season in the Sudan. He estimated the highest pod production per hectare to be 1,345 kg at a stocking density of 400 trees per hectare This is sufficient to sustain a group of animals during the dry season provided that they are supplement with other fodder.
At El Bashiroi, when in 1970 the sand dunes encroached towards the fertile soil and threatened the local inhabitants, a Prosopis chilensis shelter was planted at the foot of the dunes. It grew successfully and fixed the moving sands thanks to its ability to withstand the harsh conditions and produce roots in the subsoil as the stem is buried. In the Nile Province, it is the only tree used by the Sudan Council of Churches Project as shelter to protect the agricultural lands and villages. In the Khartoum Province it is planted as live hedge around the farms.
Prosopis chilensis was shown to have very good potential for planting in Sudan's dry zone, as it can prosper even on the hardest soils, even those which surfaces encourages water run-off. It is capable of producing a reasonable amount of firewood for the villagers and pods during the dry season for the animals. Additionally, it can stabilize the moving sands and protect settlements and agricultural lands. It is a very promising prospective afforestation tree for this region.
ahmed, a. h., 1982: “The Autoecology of Acacia tortilis (Forsk) Hayne,” Ph. D. Thesis, U. of K., Sudan.
abdel Bar, E., 1986: “The identity of the common Mesquite Prosopis spp.” Pamphlet No. 1, Prosopis Project, supported by idrc. Editor, A. El Houri Ahmed, Project Leader, frc, p.o. Box 658, Khartoum, Sudan.
abdel Gabbar, A.I., 1986: “1. Proximate composition of Mesquite (Prosopis chilensis (Molina) Stuntz) pods, seeds and leaves. 2. Digestibility Trials,” Pamphlet No.2, Prosopis Project, supported by idrc, Editor, Ahmed El Houri Ahmed, Project Leader. frc, p.o. Box 658, Khartoum, Sudan.
abdel Gabbar, A.I., 1986: “Comparative feeding of goats and sheep using pods of Mesquite (Prosopis chilensis (Molina) Stuntz),” Pamphlet No. 3, Prosopis Project, supported by idrc, Editor, Ahmed El Houri Ahmed, Project Leader, frc, p.o. Box 658, Khartoum, Sudan.
ballal, m.e., 1986: “Phenology, pod production and seed treatment of Mesquite (Prosopis chilensis (Molina) Stuntz) in the Sudan. Pamphlet No. 6, Prosopis Project, supported by idrc, Editor, A. El Houri Ahmed, Project Leader, frc, p.o. Box 658, Khartoum, Sudan.
jackson, j.k., 1960: “The introduction of exotic trees into the Sudan,” Sudan Silva Vol. 100: 14–30.
meigs, p., 1953: “World distribution of arid and semi-arid homoclimates,” In: Review of research and arid zone hydrology, Paris, unesco, Arid Zone Program 1: 203–209.
musnad, h.a., 1971: “Soil moisture conservation for plant growth in the arid climate of Northern Sudan,” thesis submitted to the University of Khartoum for the Degree of M. Sc.
mustafa, a. r. f. m., 1986: “Investigation on the plantable size of seedlings of Prosopis chilensis, (Molina) Stuntz,” Pamphlet No. 4, Prosopis Project, supported by idrc, Editor, El Houri Ahmed, Project Leader, frc, p.o. Box 658, Khartoum, Sudan.
mustafa, a. r. f. m., 1986: “The performance of Prosopis chilensis (Molina) Stuntz seedlings of various ages and sizes grown in the field under various soil working methods,” Pamphlet No. 5, Prosopis Project, supported by idrc, Editor, A. El Houri Ahmed, Project Leader, frc, P.O. Box 658, Khartoum, Sudan.
peterson, r. r., 1969: “International programme for improving arid and semi-arid range lands,” In: McGinien, Ed.: Arid Lands in Perspective, University of Arizona Press.
Forester, M. Sc.
Forestry, Universidade Federal Rural de Pernambuco
Tree planting in urban areas is important both for functional and aesthetic reasons. With the obnoxious presence of industrial and vehicle pollution, ash, excessive heat and street noise, man tends to seek out green spots to find solace.
Adequate planning of urban forestry calls for knowledge both of the characteristics of the species to be planted, and of the place they will be located, such as street width, height and location of power lines, distance to buildings and traffic flow.
Inadequate use of species, particularly in public streets, can bring about innumerable problems. Many species have been used for urban area planting in Brazil, but many times the choice of species was not made on the basis of knowledge of the tree's characteristics.
Prosopis juliflora has been increasingly used as a urban tree in cities at the Brazilian Northeast, mainly in consideration of its easy adaptation and modest water requirements.
This paper aims at analyzing the characteristics of Prosopis juliflora and its potential for use in urban forestry.
P. juliflora Characteristics as a Urban Tree
For a species to be used in streets, it is necessary to consider some characteristics such as growth habit of the tree, height, canopy, flowering and fruiting, stem and height of branching, roots, and maintenance requirements (Biondi, 1986, unpublished).
For the specific case of P. juliflora, these aspects will be analyzed below, based on literature and the author's observations.
According to Souza (1969), species with moderate growth are the most adequate for urban forestry.
Schubert (1979) considers tree height as the limiting factor in urban areas.
P. juliflora is a tall tree. Some individuals with heights in excess of 20 meters have been found at the streets of Recife, the branches reaching up to the power lines; this has made it necessary to drastically prune them (Biondi, 1985).
Moon-shaped or round-shaped canopies are the most suitable and compatible with urban environments (Wyman, 1972). Canopy density and evergreen quality are also important, particularly in the Northeast, where canopy shade is sought by pedestrians (Miranda, 1970; Pedrosa, 1983; Hoehn, 1944).
As regards the shape, P. juliflora has a vast, irregular canopy, requiring pruning and trimming to improve its shape. Its evergreen foliage, on the other hand, provides welcome shade.
Flowering and Fruiting
The use of trees with large attractive flowers for street lining is not recommended. Large flowers are inadequate as the trees may suffer damage when clipped for ornament (Souza, 1969; Miranda, 1970). Desirable are trees with small, light, dry, inedible fruit (cemig, undated; Miranda, 1970; Souza, 1969). The Companhia Energética de São Paulo (cesp) does not recommend the use of trees producing fruit of commercial value; however, planting of trees bearing wild fruit is desirable, as they can attract and feed birds (cesp, undated).
P. juliflora inflorescences are small (10-cm) green-yellowish spikes, without any particular fragrance and attractiveness, though relished by bees. The fruit is a 14- to 16-cm-long woody legume, slightly curved and flattened (Little, 1964). During the fruit bearing season, the large amount of fruits per tree is not detrimental to the tree's aesthetics, remaining yellow during the entire ripening stage, harmonizing with the permanent green of its canopy.
Stem and Branching Out
Stem and branches must have low volume, preferably devoid of thorns and sufficiently firm to withstand canopy weight and strong winds (Souza, 1969). Mello (1929) points out that it should be straight, as gnarled stems do not look good on streets or roadsides. Branching out should not start below 1.80 m for trees in constant contact with pedestrians (São Paulo, 1974; Webster, 1971).
In Recife, P. juliflora usually has a slightly gnarled stem, with a characteristic fibrous-looking bark (Biondi, 1986, unpublished). According to Biondi (1985), the mean height for branching out in this species is 1.95 m, quite within the standards recommended.
This is one of the most relevant features to be considered in street plantings. Superficial root proliferation can cause damage to pavement and even to nearby buildings (Miranda, 1970; Santiago, 1980). Species with tap roots grow considerably downward and afford the tree sufficient anchoring to withstand strong winds (Mello, 1929).
P. juliflora has superficial roots, trees being overturned by the wind during the rainy season along the streets of Recife.
Tree growth habit, height of branching out, rusticity and resistance against pests and disease are directly related with the maintenance requirements. Gray and Deneke (1978) define tree tending as all the practices necessary to keep the trees healthy, vigorous and compatible with the urban environment, such as pruning, fertilizing, and applying phytosanitary treatments. Adequate species, therefore, must require little tending, as the costs involved are high.
P. juliflora requires pruning, both to keep power lines free and to improve its appearance. As regards rusticity, several studies have pointed out P. juliflora's drought-hardiness, not shedding the leaves even during long dry periods. This is a very important aspect, particularly in the Northeast, because of the need for shade. Its rusticity is also reflected in the good adaptability to different kinds of soils (Costa et al., 1973; Franco, 1984). This species is also resistant to most pests and diseases (Bezerra and Farías, 1982). The adverse conditions in urban environments can turn trees more prone to pests and disease (Santamour, 1969). The survey of the urban trees of Recife showed that most of the existing P. juliflora did not present any sign of pests or disease (Biondi, 1985).
Use of P. juliflora in Urban Green Areas
Within the urban space, green areas are the squares and parks. Here the effects of urban forestry can be experienced more strongly, as the trees are planted in stands and because they partly integrate urban centers and ecology. Squares and parks, although not so affected by adverse conditions as streets, do require planning.
As regards choice of species, some space-related restrictions applying to streets are not important in green areas, such as tree height, canopy type and form, or type of root. From this point of view P. juliflora can be used in green areas, particularly for its good shade. According to Santiago (1980), tree characteristics in parks and squares must be as natural as possible, therefore being necessary only to carry out pruning to remove undesirable branches.
The use of P. juliflora in urban forestry is very limited. It is not recommended for street planting, on account of its superficial root system and tending requirements. In green areas, such as squares and parks, this species presents no problems limiting its use.
Prosopis juliflora in a golf club.
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sao paulo, Secretaria de Servicos Municipais, 1974: “Recomendação para o plantio de árvores nas ruas e lougradouros públicos de São Paulo,” Prefeitura do Municipio, Departamento de Parques e Jardines, São Paulo, 15 p.
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wyman, d. 1972: “Parks, malls, roadsides: public area plantings, landscape for living,” Washington, u.s. For. Service, (Yearbook of Agriculture).