Panel leader: Arturo Gómez Pompa.
Paulo César Fernandes Lima
Forester, M.Sc., Scientist Prof. at EMBRAPA/CPATSA
Petrolina-PE, Brazil
1. INTRODUCTION
Algarrobo (Prosopis juliflora (SW) DC) seeds were introduced in Brazil from Peru in 1942, at the Serra Talhada-Pernambuco District. This species was subsequently extended to the remaining states in the Northeastern Region. Thanks to its drought tolerance and high productivity, it has become one of the alternatives for reforestation at the Brazilian Semi-Arid Region.
On account of its capacity for providing fodder for sheep and goat herds during the dry season, as well as fuelwood to meet both household and industrial energy needs, algarrobo has raised considerable interest among companies and farmers in the region. This, in turn, has given rise to a demand for complementary information on species, planting methods and management systems suitable for the ecologic characteristics of the Semi-Arid Northeast. Additionally, the Federal Government, through its reforestation encouragement policy, is materializing 65 thousand ha of algarrobo in the Region.
This paper outlines the activities carried out and the results obtained by the National Forest Research Programme (PNPF) with the genus Prosopis. The main goal of these research activities is to generate technologies embodying the economic utilization of algarrobo by local farmers and business enterprises alike, and its ultimate incorporation into the regional economy.
2. A DIAGNOSIS FOR THE REGION
The Brazilian Northeast is located between 1° and 18°30' South Latitude and 30°30'–48°20' WL, accounting for approximately 18.2% of the total area of the country. The Brazilian Semi-Arid Region (Fig.1) covers 75% of this Region and 13% of Brazil.
The predominant climate is type Bsh, according to Koeppen's classification, characterized by low irregular rainfall. Rain falls over a period of 2–4 months, with an annual mean of 250–1,000 mm. Mean annual temperature stays in the neighborhood of 25°C.
Soils are generally shallow, with rocks protruding frequently, low moisture retention capacity and reduced organic matter content, red-yellow latosoil predominating.
The region is covered by a tree-shrub xerophyte plant formation known as caatinga, leguminous species predominating. Although many of these species are fodder plants, the stocking capacity of the caatinga is very small. Salviano et al. (1982), during a research study on the stocking capacity of the natural plant cover of the Brazilian Semi-Arid Region, found that 15–20 ha are required to support one head of adult cattle.
Timber productivity is low. At the forest inventories carried out in the Region, average timber volumes found ranged from 7.3 to 14.2 m3/ha (Tavares et al. 1970; Lima et al. 1979).
3. THE NATIONAL FOREST RESEARCH PROGRAMME AT THE NORTHEAST
The National Forest Research Programme (PNPF) stemmed from an agreement signed in 1977 between the Brazilian Agriculture and Livestock Research Agency —EMBRAPA— and the Brazilian Forest Development Institute —IBDF—. Its activities in the Northeast started with the Semi-Arid Tropic Agriculture & Livestock Research Centre —CPATSA—, in 1978, and presently cover all the states in the Region, including official research agencies and private companies using wood as a source of fuel.
The Northeast Programme has as its fundamental aim to select both local regional and exotic forest species apt for multiple use, with economic potential for the various zones in the Region. There are 10 scientists and 2 forest technicians working directly at the PNPF-Northeast, with the collaboration of experts from related areas assigned to the Region's EMBRAPA System executive units.
3.1 Some Considerations on the ProsopisResearch Programme
The research projects on the genus Prosopis include 32 trials distributed throughout the states of Bahía, Pernambuco, Paraíba and Río Grande do Norte. Sponsoring this programme are the CPATSA and the Agriculture and Livestock Research Agencies of the states of Paraíba (EMEPA) and Río Grande do Norte (EMPARN). Regional private reforestation companies are also conducting research in areas within their fields of action.
FIGURE 1. Location of the Brazilian Semi-Arid Region
In the first reports on the Region's programme, Silva et al. (1980) and Pires & Ferreira (1982) tell of the importance of this species for the forest development of the Northeastern Region, and show their growth at some locations in the Brazilian Semi-Arid Region. Table 1 presents height and survival rates compared to rapid growth forest species at the Petrolina-PE region, at 5 years of age.
3.1.1 Introduction of Species and Enlargement of the Genetic Base
The diagnosis of the forest situation at the Brazilian Semi-Arid Northeast made by PNPF indicates the need of enlarging the genetic base, and recommends the undertaking of studies on the behaviour of other species of the genus Prosopis in the Region. In 1973, new species from this genus were introduced from Peru, Chile and the United States of America. Species selection and provenance trials were established with this material, as well as genetic resource conservation banks.
The P. tamarugo, P. chilensis and P. alba seed lots were brought from Chile, from Tamarugal Pampa (Refresco Farm), La Tirana, Pica, Ovalle, Combarbalá, Lampa and Santiago. Seeds were collected through a joint effort of the Forestry Institute of Chile (INFOR), the National Forestry Corporation of Chile (CONAF), and PNPF. P. velutina and P. glandulosa seeds were introduced from Texas, U.S.A. P. pallida seeds were brought from the Piura region in Peru.
TABLE 1
Height and survival rates for the major reforestation species
at the Petrolina-PE Region, at 5 years of age and 3 × 2 m spacing
| Species | Surv. % | Height (m) | |
|---|---|---|---|
| Native: | |||
| Anadenanthera macrocarpa (Benth) Brenan | 93 | 2.5 | |
| Caesalpinia ferrea Mart. ex Tull | 93 | 2.2 | |
| Tabebuia impetiginosa Mart | 100 | 2.3 | |
| Exotic: | |||
| Eucalyptus crebra | 96 | 6.1 | |
| Eucalyptus camaldulensis | 94 | 5.3 | |
| Leucaena leucocephala (LAM) De Wit | 90 | 4.2 | |
| Prosopis juliflora (SW) DC | 98 | 3.2 | |
Seeds were produced by the CPATSA at the end of 1983, and the trials were established as from February, 1984, at the Petrolina (PE), Caicó (RN), Soledade (PB) and Patos (PB) districts by the CPATSA, EMPARN, EMEPA and Federal University at Paraíba, respectively. Table 2 shows survival rates for this species at three months of age, at Petrolina, PE.
3.1.2. Genetics
The great variability observed in algarrobo at the Northeast stressed the need of carrying out an up-to-then inexistant systematic work of selection of the best individuals in the region. The aims were to be —for the short term— the production of upgraded seeds, and genetic improvement in the medium and long terms. Thus, 30 mother trees of P. juliflora were selected at the Pendencia Farm (PB) in 1980 to be a part of genetic trials established at the Caicó (RN) and Soledade (PB) districts. The first findings of the analyses show a great variation in shape, growth in height and number of branches in the mother trees, and starting age for fruit bearing.
TABLE 2
Competition by species of Prosopis genus at Petrolina-PE.
(3-month-old seedlings)
| Species | Surv. % | Height (m) |
|---|---|---|
| P. tamarugo | 53 | 0.10 |
| P. juliflora | 100 | 0.95 |
| P. alba | 98 | 0.74 |
| P. chilensis | 98 | 0.76 |
| P. glandulosa | 94 | 0.53 |
| P. velutina | 98 | 0.70 |
| P. pallida | 100 | 0.76 |
With the material collected from Chile, genetic trials were established for P. tamarugo, P. chilensis and P. alba. 25 mother trees were included in the three trials, from which individuals are to be selected basing on the phenotypic characteristics, through timber and/or pod yields, and from resistance to pests and disease.
At Petrolina, a joint hybridation —CPATSA-Texas University A & I— experiment with P. juliflora and P. glandulosa var. torreyana will be established with the purpose of selecting plants with high pod yields apt for the ecologic conditions of the Northeast. Part of the seeds obtained in this experiment will be sent to the aforementioned University for frost-resistance research.
3.1.3 Vegetative Propagation
The vast phenotypic variation and cross pollination of algarrobo evidence the need of using presprouted stumps from selected trees when planting this species. Research on vegetative propagation makes P.juliflora presprouted stumps commercially feasible for the establishment of high pod and timber yield plantations.
Souza & Nascimento (1983) got 70% establishment with 10–15 cm long, 2.4–4.5 mm diameter stumps when using material from root suckers. These same authors report on the disadvantage of obtaining stumps by root suckers, since genetic material is lost as a result of the need of cutting the trees. It is easier to obtain material from the upper branches (crown), despite the lower rates of establishment, and it is not necessary to fell the mother tree.
With the purpose of investigating the action of auxines and leaves in the root formation of stumps from 7-year-old P. juliflora branches, different concentrations of indolbutiric acid (AIB) and percentage of leaves in 15-cm-long, 4.4 cm diameter stumps, were tested. From the findings —67% establishment—, it may be recommended to leave 100% of the foliar area in the stumps, and make a treatment with a 2,000-ppm AIB solution.
3.1.4 Pests and Disease
Santos & Silva (1980) found that P. juliflora was host to Meliodogyne javanica (Treub 1885) Chitwood 1949. However, this pest did not hinder seeding survival rates.
In a study of the insects associated with the forest seeds of the Brazilian Semi-Arid Region, Moraes et al. (1981) found Bruchidae in P. juliflora seeds, identified as Mimosetes mimosae (F).
Signs of attack by the grasshopper Stiphra robusta Mello-Leitāo are periodically observed, affecting notoriously the amount of leaves in caatinga species. However, no damage by this species has been observed in P. juliflora.
Carvalho et al. (1968) report on attacks of the sawing insect (Oncideres limpida Lates) in algarrobo, at some districts of the State of Pernambuco. Lima (1982) also observed the presence of, and damaged caused by, this insect in 3-year-old P. juliflora, at the Petrolina-PE district.
3.1.5 Seeds
P. juliflora seeds are difficult to extract from the pods, a fact which imposes certain constraints in obtaining material for large scale plantation. For this reason, methods for extracting large amounts of P. juliflora seeds at low cost without affecting germination rates have been tested. Souza et. al. (1983) obtained the best results using two methods: hand mill and fodder machine with sun-dried P. juliflora pods.
Seeds obtained with the hand mill do not require pre-germination treatment, as this process causes a groove in the tegument which facilitates water penetration. Due to the reduced germination viability of this seeds when stored for long periods, as the grooves become more prone to deterioration, research was undertaken on their storage. The findings obtained in the first months show 61% viability for seeds treated in a fodder machine, stored in a cold chamber at 8°C and with 50% relative humidity, or 67% in ambient conditions. For the manual extraction process, results were 77% and 70% for seeds stored in cold chamber and room conditions, respectively.
3.1.6. Agrosilviculture
Agro-silvo-pastoral systems constitute an important alternative for land use optimization at the Brazilian Semi-Arid Region. CPATSA is conducting research on the association of timber and/or fodder forest species with some crops tolerant to drought. The purpose is to obtain, simultaneously, wood for energy generation at rural properties and fodder for livestock herds.
In a study of the influence of management practices on the survival and development of P. juliflora in association with Cenchrus ciliaris L. cv. gaydola, Ribaski (1983a) showed the need of keeping an area clear of any vegetation, with a minimum diameter of 2 m, around the P. juliflora plant. Ribaski (1983b) observed a 60% decrease in P. juliflora associated with Cenchrus ciliaris L. cv. biloela in the first 9 months of establishment, due to the damage caused by cattle grazing freely in the area. The P. juliflora plants not protected by a fence showed smaller growth both in height and crown development than those protected from animal intrusion.
A trial testing the association of P. juliflora and Agave sisalana was also established at CPATSA. This trial has as purpose to determine the biologic and economic viability of this association. The Agave fibers are to be used for pulp manufacture, and the waste from this crop, added to the P. juliflora pods, will be used as feed supplement for livestock. Agave is also used for cord manufacturing at certain areas in the Northeast.
Shading trials of Opuntia ficus indica by P.juliflora were also undertaken at CPATSA, with 5 × 5 m; 7 × 7 m; 10 × 10 m; and 12 × 12 m spacing for P. juliflora, and 2.0 × 0.5 m for Opuntia ficus indica. This trial is still in its second year, without any meaningful results. At the CPATSA demostration plots for local farmers, P. juliflora was planted at 10 × 10 m spacing in association with Opuntia ficus indica spaced at 3.0 × 1.5 × 0.5 m, and the dry matter yield at 2 years of age was 11.2 ton/ha. Sorghum bicolor Moench was planted in the clearing between the trees, during the first two years, with annual yields of 437 and 583 kg/ha, respectively. Close to 5% of the P. juliflora trees started to produce pods as from the second year; however, total output was not evaluated for the trees.
3.1.7 Inoculation
EMBRAPA has conducted research aimed at obtaining more efficient Rhizobium strains in the fixation of atmospheric nitrogen. The work carried out by Franco (1982) made it possible to select the strains Br 4001, Br 4002, Br 4003, Br 4007, which proved more efficient in the nodulation and N2 fixation processes. Basically, seed inoculation makes it possible to disregard nitrogen fertilization, as it insures good growth rates for the seedlings.
Moreira et al. (1982), in a research study on P. juliflora seedling production in pots with high phosphate concentrations, found that the Br 4002 and Br 4007 Rhizobium strains are efficient in producing abundant nodulation, fixing the necessary nitrogen for the development of the plant.
Currently, at all research works under way undertaken by PNPF, seedlings are inoculated with the specific Rhizobium for the regional conditions. The Northeastern Region Foresters have been given the specific inoculant for seedling production at their plantations.
3.1.8 Pod Production
The great variation observed among the trees with regard to their pod yields under the conditions found in the Brazilian Semi-Arid Region was recently demonstrated. Pod yields for 15-year-old P. juliflora plants growing at the same site and occupying similar vital area, were found to range from 5 to 111 kg/tree/year (Fig.2). In 2-year-old P. juliflora plantations with 10 × 10 m spacing, mean pod yield was 0.7 kg/tree/year. In general terms, pod production begins in this region at the end of the rainy season.
3.1.9 Watershed Management
The influence of reforestation with P. juliflora on water availability and quality at the region's watersheds is being investigated through the project implemented at Cruceta (RN) by EMPARN. The influence of native vegetation and of reforestation with P. juliflora is being studied in relation with open soils under annual crops.
3.1.10 Timber Production
Trials undertaken at the Petrolina area (State of Pernambuco) with P. juliflora and L. leucocephala, with 3 × 2 m spacing, yielded 7.2 and 7.8 m3/ha of timber at three years of age, respectively. As from this age, the P. juliflora plants stopped growing, probably on account of soil and propagation constraints.
CPATSA is carrying out a spacing trial with P. juliflora at the province of Euclides da Cunha (State of Bahía) —still without significant results—, with the purpose of establishing its timber productivity at that region.
3.1.11 Fertilization and Nutrient Cycling
The trials conducted by CPATSA have as purpose to evaluate, in a comparative analysis, the effect of mineral nutrients (P, K) and of the manure used in the traditional planting systems. The combined effect of inoculants and fertilization is being studied in specific EMPARN programmes, using presprouted P. juliflora stumps as seedlings.
FIG. 2. Accrued P. juliflora pod output at 15 years of age. Petrolina - PE.
(May 1983 - April 1984)
Comparative studies of P. juliflora, L. leucocephala and natural caatinga vegetation show that the reposition of mineral elements through the dry weight of leaves, fruit, sprouts and flowers reached, in the 10 months of observation, a total of 463, 617 and 794 kg/ha, respectively.
3.1.12 Seedling Production and Plantation Systems
P. juliflora seedlings may be produced in polyethylene or laminated bags, and fertile-pots. The best root weight-dry weight of aerial portion ratio occurs for seedlings raised in plastic cylinders. Seedlings in all treatments showed 100% survival rates 30 days after being transplanted in the field.
EMPARN is carrying out research work on P. juliflora plantation methods, using seedlings pruned both at the roots and aerial portion (stripling), naked root and direct seeding. The seedlings from the stripling treatment showed very satisfactory results for semi-arid conditions. One of the advantages of this system is the easiness and economy of transportation of the seedlings to the planting site.
Plantation systems for P. tamarugo are presently being tried in CPATSA using clay pots, in situ rainfall water collection and soil covering with a plastic sheet to prevent moisture loss by direct evaporation. The first findings of these trials show the viability of tamarugo plantation with the use of clay pots and vermiculite in this region. Table 3 shows the findings of this research work, at 3 months of age.
TABLE 3
Survival rates of P. tamarugo seedlings
under different planting systems at three months of age.
Petrolina - PE.
| Planting System | Vermiculite | |
|---|---|---|
| With | Without | |
| Clay Pots | 50 | 86 |
| Rainwater collection | 70 | 56 |
| Without rainwater collection | 66 | 70 |
| Covered by plastic sheet | 70 | 70 |
Results have been satisfactory for P. juliflora, at a site with in situ rainwater collection over a period of 6 months, with organic fertilizer and using an inert cover.
3.1.13 Utilization of Saline Soils
Salinization of soils in irrigated areas at the Northeastern Region is a serious problem. The Northeast Agriculture Department (SUDENE) has inventoried 25 per cent of the irrigated area in the Northeast as having salinity problems or undergoing a salinization process.
With the purpose of introducing alternatives for effective land use at those salinized areas, a trial to evaluate the performance of P. alba, P. chilensis, P. juliflora, P. pallida and P. tamarugo was established at the irrigated perimeter of São Gonçalo (State of Paraíba), which salinized area accounts for 28% of the irrigated land.
Other trials established in this same area with P. juliflora, E. camaldulensis, L. leucocephala and various indigenous species from this region, showed P. juliflora as the only species tolerant to the saline conditions.
4. RESEARCH LINES
The first results obtained with the introduction of P. juliflora into the Brazilian Northeast showed its potential as a reforestation species for the semiarid region, for purposes of timber and pod production.
In light of the great variation observed in P. juliflora pod yield, its fruit bearing and growth precocity, genetic improvement research must be encouraged, in order to form hybrids and identify high timber and pod yield strains.
Fuelwood production from P. juliflora has been limited by the little information available on the appropriate stocking rates, habitat and management, among other factors. Further research is therefore recommended to design agro-silvo-cultural systems including multiple use of P. juliflora.
Tree collapse by heavy rain and wind may affect the economic performance of the areas reforested with P. juliflora. It is mandatory to devise conservation measures for the preservation of these areas.
REFERENCES
CARVALHO M.B. de, CARVALHO E.P. de & ARRUDA, G.P. de. O “Serrador”: praga da algarobeira. Recife, PE, Instituto de Pesquisas Agronómicas de Pernambuco, 1968. 26 pp. (IPA. Boletim Técnico, 33).
FRANCO A.A. Fixaçào de N2 atmosférico em Prosopis juliflora (SW) DC. In: Empresa de Pesquisa Agropecuaria do Rio Grande do Norte, Natal, RN. Algaroba. Natal, 1982. pp. 319 – 29 (EMPARN. Documentos, 7).
LIMA P.C.F. Comportamiento silvicultural de Leucaena leucocephala (LAM) De Wit comparado a Prosopis juliflora (SW) DC e Eucalyptus alba Reinw, ex Blume em Petrolina (PE), regiao semi-árida do Brasil. Curitiba, Universidade Federal do Paraná, 1982, 96 pp. Tese Mestrado - Silvicultura.
LIMA P.C.F., DRUMOND M.A., SOUZA S.M. DE & LIMA J.L.S. de. Inventario florestal da Fazenda Canaá. In: Congresso Florestal Brasileiro, 3, Manaus, AM, 1978. Silvicultura, São Paulo, SP, (14): 392–3, 1979. Edição Especial. Anais V.2.
MORAES G.J. de, RAMALHO F.S., SOUZA S.M. de, SILVA, C.M.M. de S., LIMA P.C.F. Insetos associados a sementes de forrageiras e essências florestais no trópico semi-árido do Brasil. Petrolina, PE. EMBRAPA - CPATSA, 1981, 2 pp. (EMBRAPA - CPATSA. Pesquisa em Andamento, 11).
MOREIRA V.C.G., SILVA E.M.R. da, FRANCO A.A. & DOBEREINER J. Produção de mudas de algaroba (Prosopis juliflora) em recipientes com altas concentrações de fosfato de rocha. Rio de Janeiro, 1982. 11 pp. Trabalho apresentado no I Simpósio Brasileiro do Trópico Semi-Arido, Olinda, PE, 1982.
PIRES J.E.& FERREIRA C.A. Potencialidades do Nordeste do Brasil para reflorestamento. Curitiba, EMBRAPA-URPFCS, 1982. 30 pp. (EMBRAPA-URPFCS. Circular Técnica, 6).
RIBASKI J. Influência de tratos culturais na sobrevivência e no desenvolvimento de Prosopis juliflora (SW) DC, associada a capim buffel. s.n.t. 1983a. 3 pp.
RIBASKI J. Sobrevivência e desenvolvimento de Prosopis juliflora (SW) DC, plantada em área de capim buffel sob pastejo. s.n.t. 1983b. 3 pp.
SALVIANO L.M.C., OLIVEIRA M.C. de SOARES J.G.G., ALBURQUERQUE S.G. de & GUIMARAES FILHO C. Diferentes taxas de lotação em áreas de caatinga. I. Desempenho animal. In. Reunião da Sociedade Brasileira de Zootecnia, 19, Piracicaba, SP, 1982. Anais Piracicaba, SP, Sociedade Brasileira de Zootecnia, 1982. p. 365–6.
SANTOS J.M. dos & SILVA H.D. da. Suscetibilidade de espécies florestais á Meloidogyne javanica na região semi-árida do Nordeste. In: Simposio IUFRO em Melhoramiento Genético e Productividade de Espécies Florestais de Rápido Crescimento, Aguas de São Pedro, SP. 1980. Silvicultura, 8(30): 378–9, maio/jun. 1983. Anais.
SILVA H.D. da, PIRES J.E., RIBASKI J., DRUMOND M.A., LIMA P.C.F.L., SOUZA S.M. de & FERREIRA C.A. Comportamento de essencias florestais nas regiões áridas e semi-áridas do Nordeste. (resultados preliminares). Brasília, DF. EMBRAPA-DID, 1980.25p. (EMBRAPA-DID. Documentos, 1).
SOUZA S.M. de & NASCIMENTO C.E.S. Propagação vegetativa de algaroba por estaquia. S.N.T. 1983. 12 p.
SOUZA S.M. de, LIMA P.C.F. & ARAUJO M. de S. Sementes de algaroba: métodos e custos de beneficiamento. R. bras. Sem., Brasília, 5(3): 51–61, 1983.
TAVARES S., PAIVA F.A.V., TAVARES E.J. de, CARVALHO G.H. de & LIMA J.L.S. de. Investário Florestal de Pernanbuco. Estudo preliminar das matas remanescentes dos municipios de Ouricuri, Bodocó, Santa Maria de Boa Vista e Petrolina. B. Rec. nat., Recife, P.E, 8: 149–93, 1970.
Fernando Squella
Agriculture Engineer, M.S.
Agriculture and Livestock Research Institute (INIA)
Raúl Meneses
Agriculture Engineer
Agriculture and Livestock Research Institute (INIA)
The arid Mediterranean tendency zone in Chile is located primarily between 29° and 32° S (Fig. 1), covering a large part of the Coquimbo province and, in a lesser degree, the Atacama region.
The climate in this area is characterized by a colder humid season during the winter and a warmer and drier season during the summer. The predominant climatic factor is the short rainy season, lasting 3 months in the northern portion of this region, with an annual average of 80 mm and 46% probability of drought year (65 mm or less), and 5 months in the southern part, with 300 mm on average and 22% probability of dry year (219 mm or less). The rest of the year is dry. Rains fall mainly in winter, when the temperatures are lower and the potential evapotranspiration amounts to 1.3-1.1 mm per day (Gastó 1966; INIA, 1977).
The fact that the unwatered croplands in the Coquimbo Région are subjected to an arid Mediterranean climatic regime, with rainfall varying from 96 mm to the north of La Serena to 312 mm south of Los Vilos, and that the topography is mostly rugged, make the land clearing and furrowing activities for unwatered crops a risky business, not only from the low yields —primarily conditioned by the low rainfall—, but also, on the longer term, due to the progressive deterioration of both biotic and abiotic resources. It is in light of this that, within an agricultural and livestock raising context, the option best adapted to the available resources and which best guarantees their conservation is the transformation of the present plant cover —useless to man as it is— into food and raw material (meat, milk, wool, leather, pelts, etc.) through a rational exploitation with domesticated or wild species.
The balance between the primary productivity of the plants and the secondary productivity of the animals browsing and grazing them is difficult to establish and, furthermore, to respect once it has been determined, particularly under such conditions as those encountered here, where a considerable rural demographic pressure bears down on the scant resources available (Lailhacar, Squella & Bernstein 1977).
A study conducted in 1977 by the National Planning Office (ODEPLAN) found that the Coquimbo region had the highest share of the population under conditions of extreme poverty (30%, and of the 102,230 people in this situation, 56,357 are rural residents). Approximately 70,000 people, including this latter group and others from the semi-urban sector, live in the Agricultural Communities of the region.
These communities cover an area of 946,925 ha and are based on the common property of the grazing, crop, and fuelwood-producing lands and on the private property of very small irrigated areas. The overstock of animals, particularly goats, competes with the indiscriminate cultivation of the soil and the sustained extraction of firewood, which, combined, are accelerating the desertification process inherent to this environment (Bonilla, Squella & Meneses 1983; Lailhacar, Squella & Bernstein 1977).
The Agriculture and Livestock Research Institute (INIA), aiming at increasing agricultural and livestock production in the nation through the design, adaptation and transference of technology, and aware of the rapid desertification process affecting these areas as a result of the practices described above, deems it absolutely essential to timely obtain and channel a greater amount of resources to check the negative effects of an inadequate interpretation of the actual reaction capability of the natural resources involved (entailing a loss of the plant cover, a decrease in the natural fertility of the soil, microclimatic changes, modification of the contribution of the watersheds and emigration of the wild fauna toward areas with greater ecological stability). Envisioned are increased productivity through productive systems capable of generating conditions and goods useful to man, including the conservation of the soil and water resources, protection and production of fodder for wild and domesticated animals, the introduction of new primary sources to provide human food, energy, shelter to animals, the reclamation of areas contaminated by industrial, mining and other activities, and the conservation of resources of scientific, aesthetic or recreational value (Squella & Meneses 1981a).
Figure 1. Climatic Map of Chile
| A. | DESERTIC TENDENCY ZONE | |
 | 1. | Coastal desert region |
 | 2. | Inland desert region |
| B. | TROPICAL TENDENCY ZONE | |
 | 3. | Marginal tropical region |
 | 4. | High altitude tropical region |
| C. | MEDITERRANEAN TENDENCY ZONE | |
 | 5. | Perarid Mediterranean region |
 | 6. | Arid Mediterranean region |
 | 7. | Semi-arid Mediterranean region |
 | 8. | Sub-humid Mediterranean region |
 | 9. | Humid Mediterranean region |
 | 10. | Perhumid Mediterranean region |
| D. | OCEANIC TENDENCY REGION | |
 | 11. | Oceanic region with Mediterranean influence |
 | 12. | Cold temperate oceanic region |
 | 13. | Sub-antarctic oceanic region |
 | 14. | Trans-Andean oceanic region |
| E. | CONTINENTAL TENDENCY ZONE | |
 | 15. | Andean region |
Source: Di Castri, 1968, en INIA (1977)
At the Los Vilos Experiment Substation (INIA), located at the southern sector of the coastal semi-arid unwatered zone, applied research activities have been conducted since 1976, aimed at achieving optimum management and utilization of the soil and water resources and obtaining maximum primary and secondary productivity, with a view to the conservation of the natural resources. The basis for this effort are the possibilities for generating and transferring technologies embodying a better utilization of the existing resources or of those likely to be introduced into that environment (Bonilla, Squella & Meneses 1983).
An important boost was given to the activities at the aforementioned experiment substation by the UNDP/RLA/74/018 Project on “Applied Agricultural Research in Arid and Semi-Arid Regions”, stemming from a joint agreement between the Inter American Development Bank (IDB) and the Government of Israel, with INIA acting as national counterpart on behalf of the Government of Chile. Additional participants were Argentina, Bolivia, Paraguay, Peru and Venezuela.
The project included missions of experts to analyze aspects related to hydrology, primary and secondary production, and research carried out by national personnel on duty at the Experiment Substation.
The first mission in November 1975 —repeated in February 1977— had the purpose of analyzing the hydrological characteristics of the region, determining the more important parameters and designing some work on watershed management and erosion control (Rosenzweig 1976a & 1976b; Rosenzweig, Harpaz & Bernstein 1977).
Another mission related to the unwatered fodder resources analyzed the research presently under way at various experiment centers and the management practices applied at the area. Some actions were proposed and recommendations on the subject were made, taking into consideration the problems encountered in the region, which provided the basis for an operations plan (Forti & Squella 1976).
During the same period of time, two other missions related to the improvement of sheep and goat production (Eyal & Crempien 1976) and to the utilization of fodder shrubs to increase livestock production (Seligman et al. 1977) were carried out. Technical solutions of a practical nature were suggested on the livestock management of the area, focused specifically on sheep and goats and the extreme climatic situations occurring at the area (Benjamin 1980).
The outcome of the project was the formulation of an investment pre-project to develop a pilot unit to irradiate technology possible to be applied by the agricultural communities of the region (SERPLAC-Region IV 1979).
MORE RELEVANT RESULTS
The local shrub Atriplex repanda had been noticed to stay green during the dry season, and that the animals browsed from it, particularly in drought years. Thus, the systematic utilization of this shrub during the dry months started to be studied as a solution to fodder scarcity. Several institutions initiated research projects focused on this species, about which Olivares and Gastó (1981) provide a very thorough compilation of data.
Special attention was granted at Los Vilos to the study of natural rangelands and fodder shrubs (Squella, Gutiérrez & Meneses 1981), for which purpose observations and records were simultaneously started, aimed at determining the relationships among the climatic, soil and biological variables. After a few years, it has been possible to integrate the major factors, and formulate a sheep production system which is first being evaluated at the Experiment Substation itself, later to be transferred to animal stock owners (Meneses & Squella 1981).
1. Grazing Systems
In general terms, the present productivity of the herbaceous layer is far too low, as a result primarily of overgrazing. The highest stock support rates do not exceed 0.4 sheep/ha, as the plant cover is composed by species with very low fodder value, such as Aira caryophyllea, Plantago hispidula and Vulpia sp. With a view to increasing fodder supply, a trial with natural rangelands, including exclusion, deferred grazing and continued grazing, was initiated. After three years, a marked rise in production was obtained both at the exclusion and deferred grazing treatments. At five years, productions were attained amounting to 3,500; 2,000 and 1,000 kg DM/ha at each of the three treatments, respectively. Additionally, some native perennials started to increase their development, such as Piptochaetium stipoides and Stipa duriuscula, with over 40% presence coefficient. Avena barbata and Erodium sp. were also seen to increase their presence (Gutiérrez, Squella & Meneses 1979 and 1980; Squella & Meneses 1981b; 1982a and 1983a).
2. Post-Grazing Residue
Findings similar to those obtained at the trials have been observed at the areas with fodder shrubs subjected to exclusion for a relatively long period of time after planting. Despite this fact, the farmers have been slow to react and accept a similar management practice for the plots with no fodder shrubs. It was necessary to identify the factor or factors favoring the recovery of the rangeland when subjected to exclusion or deferred grazing, to propose the farmers to undertake a more viable and less costly alternative for the management of their lands. Thus, the residual plant cover remaining after grazing has been shown to be an important factor in the subsequent improvement of the rangeland. Limiting the amount of grazing in order to leave a given amount of residual plant cover until the beginning of the next growing season can be a more acceptable alternative for the farmers.
The findings of the trials after three years show a high correlation between the residual plant cover and the fodder yields obtained in the next season. Most relevant, though, is the effect on the botanical composition. When the residual plant cover diminishes, low fodder value species such as Plantago hispidula and Vulpa megalura become more notorious, increasing as well the area of barren lands (Squella & Meneses 1982b and 1983b). On the contrary, with a higher proportion of residual plant cover, such desirable species as Piptochaetium stipoides and Avena barbata, more palatable to livestock, grow more profusely.
The application of such practices as described above can help to increase the pasture resource and conserve the soils, without any need of making large investments, as in the case of fodder shrub plantations.
3. Fertilization and Self-Seeding Species
It is also possible to increase the production levels through the application of nitrogen and phosphate fertilizers. The overcropping of the land has diminished its fertility, particularly nitrogen availability, which in many cases does not exceed 4 to 10 ppm.
Experimental application of 16; 64 and 128 units of nitrogen/ha as potassium saltpeter, controled over three years with climatic conditions (according to the classification proposed by Gastó [1966] rated as rainy, normal and rainy, respectively, showed increases of 33.4%; 50.1%; 65.8%, and 77.2%, respectively, over a yield of 2,381 kg DM/ha in the control treatment. On the other hand, the application of phosphorus as Triple Superphosphate did not produce any significant increases (Squella & Meneses 1982c and 1983c).
While these yield increases may be rated as interesting, it is necessary to carry out an economic analysis including these practices within an encompassing agricultural system, capable of maximizing the utilization of the resources. It is unlikely to achieve higher output rates under arid or semi-arid conditions, but management systems can be formulated to reach and maintain the indicated output levels.
In an experiment on the establishment of self-seeding species with low water requirements, outputs of 3,530 and 2,812 kg DM/ha were obtained with Medicago truncatula cv. Ghor and Jemalong, respectively, although the reseeding measured at the following season was not satisfactory (Gutiérrez, Squella & Meneses 1979).
4. Fodder Shrubs
The grass layer constitutes an excellent fodder resource, but the great variation in the water conditions affects the species making it up, and the long dry season every year limits this resource to only a short time. For this reason, the establishment of fodder shrubs can be very important to offset the fodder deficit, particularly during the dry season and during the periods with greater physiological demands of the animals.
The first work aiming at the establishment of fodder shrubs such as Atriplex repanda (Phil.) and Atriplex nummularia (Lindl.) intended to increase the germination rates of the seeds. Treating the seeds for 45 min with sulphuric acid and potassium hydroxide achieved a germination rate of 84% and 30% for A. nummularia and A. repanda, respectively (Squella, Gutiérrez & Meneses 1981). The plants obtained showed considerable heterogeneity, a fact also confirmed by Lailhacar, Cristi & Azócar (1980), when they found significant genetic differences among different provenances of the genus Atriplex. For this reason, it was attempted to obtain plants through vegetative propagation. Good establishment rates can be obtained with cuttings with low lignification, raised in winter and spring. The procedure requires no special conditions nor the application of hormone substances. Among the species tried, it has not been possible to obtain good establishment rates for Acacia cyanophylla, the reasons for which are still unknown (Peña 1979). Other species, such as Galenia secunda, Atriplex halimus, Atriplex lentiformis, Medicago arborea, etc., have shown good propagation (Gutiérrez, Squella & Meneses 1979).
As the development of the fodder shrubs after planting is slow, the effect of the application of nitrogen and phosphate fertilizers, both individually and combined, was tested. The findings showed the nitrogen application as giving higher growth rates, higher DM output, greater size for the basal section of the stem and better recovery after grazing. No response was obtained for the phosphorus application nor for the interaction of both compounds (García-Huidobro, Squella & Meneses 1983). This has been corroborated by Cargano and Lailhacar (1980).
The shrubs were planted at a stocking rate of 1,100 plants/ha, according to a work carried out by Gastó and Contreras (1972), with 3 × 3 m spacing. The observations at Los Vilos agree with the above, and show that, despite higher fodder output per unit of area in denser plantations, there is a clear tendency to increased production at the less dense plantations in later years. This trial is being conducted with Atriplex repanda and Atriplex nummularia, grazed by sheep during the dry season (Gutiérrez, Squella & Meneses 1979; Squella, Meneses 1979; Squella, Meneses 1981c and 1982d).
Species such as Galenia secunda (Squella & Gutiérrez 1980) and Atriplex semibaccata (Mancilla, Silva & Santibáñez 1976) have been successfully established by direct seeding, which entails a considerable decrease in the costs involved for the establishment of fodder resources in that area.
5. Species Adaptability Trials
There are currently some 20,000 ha planted mainly with Atriplex repanda and Atriplex nummularia and, in a lesser degree, Acacia cyanophylla and native species in Region IV. The latter species mentioned—native—should be used, in a livestock raising system, to offer shelter and shade for the animals. An introduction nursery was established at Los Vilos to test other species with good adaptation potential, including 33 species from various arid regions in the world. Among them, the following were outstanding: Atriplex semibaccata, Galenia secunda, Atriplex halimus and Atriplex glauca (Gutiérrez, Squella & Meneses 1980; Squella, Meneses 1981d). However, there are other species which might show better adaptation under more favorable soil and climatic conditions in other sectors within the region.
Taking the above into consideration, this research was expanded towards the area south of Los Vilos, establishing acclimation nurseries in an area with higher rainfall (300–500 mm yearly), with financial support from the Government of Region V-Valparaíso. After three years of observations and data recording, the following were observed to have outstanding performance: Galenia secunda, Acacia cyanophylla, Atriplex nummularia and Atriplex lentiformis. Furthermore, a significant increase in the production of the herbaceous layer was also evident under these conditions, including favorable changes in the botanic composition. Obviously, prior to establishing any shrub species —usually entailing sizable investments— it is recommended to manage rationally the existing natural resources (Squella, Meneses & Gutiérrez 1983).
6. Predicting the Available Soil Moisture
The work on fodder shrub reinforced natural pastures was complemented with readings of the soil moisture content resulting from rainfall. The analyses, carried out over a period of 6 years, indicate that moisture is normally available to the plants from May to October, with some variation depending on the rainfall regime (Squella & Meneses 1983a).
The data obtained were used to devise a method to forecast the moisture content of the stratified soils in semi-arid zones, using a combination of the Continuity Equation and the Law of Darcy. The results indicate that the model designed can be used in arid zones to determine the state of the soil moisture under any condition, providing that certain hydro-mechanical parameters of the soil are known. It was further concluded that the loamy stratum of the soil profile stores water gradually during the humid season, to be partly used by the existing perennials during the dry season (Bernstein 1980).
Concurrently, another model was designed —based on the water balance— to estimate the effect of contour furrows on the soil moisture content. The working hypothesis was that the contour furrows check erosion and water loss derived from runoff, which, instead, would accumulate in the soil strata, thereby increasing water availability. This latter point was indeed confirmed, evidencing different rates according to the horizon. At horizon A (sandy) the availability is limited and there is no significant difference among furrows 3 to 6 m apart; at horizon B (loamy), water availability is considerably higher, reaching maximum values when the spacing of the furrows is 3 m. The model makes it possible to estimate the annual variation in the water content of the soil and assess the water recharge by furrow in both soil horizons, giving a more accurate reading for the recharge at horizon B than the experimental measuring itself (Novoa 1979).
The greater water availability should entail better establishment rates and enhanced productivity by the plant species adapted to aridity, and the possibility of establishing more productive species which would not normally prosper in this environment due to the limited water supply.
Basing on the above findings, most of the extensive plantations have been preferentially established on contour furrows. In some sectors where it was not possible to apply this system, modifications intended for the same purposes were introduced.
The fodder yield evaluation of Atriplex repanda and Atriplex nummularia established in contour furrows, in pits designed to catch runoff water and others in simple pits showed the in situ water harvesting systems to be more efficient. However, in areas with lower rainfall, the pits designed to catch runoff water proved more effective (Soto 1982).
7. Livestock Production Systems
According to the 1976 agriculture and livestock census, there are 150,000 sheep and 500,000 goats in Region IV. The former are kept mainly at the privately owned lands, while the latter are kept in agricultural community lands.
All the experimental work carried out at Los Vilos is intended primarily to increase fodder availability for livestock, so that, with simple and easy-to-adopt techniques, the local farmers can produce more meat, wool or milk on a sustained basis preserving and improving, at the same time, the available natural resources.
Within this framework, a sheep production system was designed and started at Los Vilos in 1981, based on the use of the natural rangeland between the months of August through May, both included. During the remaining months, a natural pasture reinforced with fodder shrubs is used strategically, particularly during the last third of pregnancy and during lactation. This pasture covers 25% of the total area, and is divided into three sections that are grazed at different times. There is always one section that is excluded throughout the whole year; another one which is grazed from August through October —which will be excluded during the entire coming year—, and a third —excluded the previous year— which is used from January to May or June and, again, in November and December (Fig. 2). Figure 3 illustrates the productive flow scheme for the animals under this production system.
The duration of the grazing period varies according to the fodder availability resulting from the rainfall conditions of each year. Thus, in rainy years the fodder shrubs are subjected to light grazing and the natural pasture to more intensive grazing. On the contrary, in drier years the use of fodder shrubs is more intense. An average animal stocking rate of 0.92 sheep eq./ha has been used, with lambing rates of 90%. The amount of fodder availability recorded over the three years —which corresponded, respectively, to normal, rainy and normal — point to a capability for increased animal load. It is nevertheless necessary to always bear in mind the occurrence of drought years. In any case, the basic management applied to both pasture and animal resources has permitted to increase sheep production by 60% with respect to the averages recorded at this zone. This means 19.1 kg/ha and 3.3 kg/ha of meat and wool, respectively.
By means of complementary practices, greater production increases can be achieved. The experimental results obtained at Los Vilos indicate that an alfalfa hay (Medicago sativa) prebirth supplement increases notoriously the live weight of the sheep at weaning and shearing, with greater wool yields and higher lamb weight at birth, branding and weaning. This practice, additionally, allows for a greater amount of residual plant cover on the grazed pastures, favoring the initial growth during the following season (Crempien & Squella 1978).
The protein level of Atriplex repanda and Atriplex nummularia obtained at the shrub pastures of los Vilos amounts to 18%–20% and 14%–15% crude protein, respectively. This amount is significant if compared to the 6% observed for the standing hay at the annual pasture. However, this large difference was not reflected by the weight of the ewes grazing on shrubs, as they achieved the same weight as those grazing the standing hay (Meneses 1980). Nevertheless, the greater fodder availability at the pasture containing shrubs allows for higher production per unit of area.
The contribution of the fodder shrubs in the production system described above was low. However, in other assessments carried out in extensive plantations, located to the north of Los Vilos, yields of 600–800 kg DM/ha were recorded, amounts which, in many cases, represent over 50% of the residual availability of the deferred pastures. Under these conditions, and with adequate management, fodder shrubs do constitute an important contribution to the fodder supply during the dry season (Meneses 1983).
8. Economic Studies
With the technical background data obtained at Los Vilos and using market prices valid for 1980, a theoretical economic study was made, comparing a production system with shrubs to others without shrubs. In a normal year and a dry year, better income was obtained from the fodder shrub system. The production costs, considering the benefits of the state's subsidization of the plantation, were greater for the fodder shrub system, but the profitability of the invested capital was 9.13% and 9.58% for the system with and that without fodder shrubs, respectively. It is necessary to assess the real costs in a commercial farm, where the fixed costs are certain to vary and improve the profitability of the fodder shrub system. When drought periods and their consequences on the market prices of the products were taken into consideration over a period of ten years, favorable economic results were obtained for the fodder shrub system (Arroyo & Meneses 1980).
The following alternatives were considered in a more detailed study (Cerda & González 1982):
Figure 2
Deferred grazing at a natural pasture for sheep production
Los Vilos
Source: Meneses & Squella (1982).
Figure 3
Productive flow scheme for sheep production system
Los Vilos
Source: Meneses y Squella (1981).
The study showed positive profitability for the second and third alternatives, with a computed internal rate of return (IRR) of 47% and 33% respectively. These rates are lower during drought periods, but in no case too low to become unattractive. On the other hand, it was clear that it is not possible to carry out any plantations without the benefits of state subsidization as established under Decree Law 701.
Considering the situation of extreme poverty in the arid and semi-arid unwatered lands of the Coquimbo Region (Region IV), particularly in the agricultural communities, it is concluded that the fodder shrub establishment project, with the benefit of state subsidization and profiting from the current state of knowledge, is socially profitable.
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Virgilio Roig
Agronomist
Former Consultant with PNUMA.
Researcher at the National Scientific and Technical Research Council
Argentina
INTRODUCTION
A short distance from Port-au-Prince and near the borderline with the Dominican Republic is Thomazeau, a village with peculiar characteristics from the point of view of forest exploitation, worthy of a separate analysis.
GEOGRAPHIC SITUATION
Thomazeau is located at the Northeastern section of the Cul de Sac Plains, forming part of the basin; it is 78 km2 in area, a sizable part of which is taken up by the northern mountains, particularly the Trou d'Eau Range. To the west it borders on a line stretching from Etang Trou Caiman to Fond Michel, skirting the Port-au-Prince-Mirebalais road.
To the east it borders on the water division line starting at Etang Maneville and reaching towards the Northeast, crossing the Thomazeau-Grand Bois road.
Its northern border is the drainage line of the Artibonite (Fond Michel-Nan Mapou-Morne Trou d'Eau Masson), and the southern border is the drainage area known as Desagua, starting from the Etang Trou Caiman towards the Etang Saumatre.
POLITICAL SITUATION
Thomazeau is one of the five communal districts of the Croix des Bouquets.
The studied region is a basin extending over five rural sections corresponding to three communes: Thomazeau, Mirebalais and Grand Bois.
The sections are Grande Plaine (Thomazeau), Gascogne (Mirebalais), Crete Brulée (Mirebalais) and Plaine Céleste (Grand Bois).
ECOLOGIC SITUATION
The marked variations in rainfall, topography, altitude, exposition, etc., delimit two well defined ecological zones within the basin:
a. The Semi-Arid Zone:
Here rainfall does not exceed 800 mm annually, with two rainy seasons: April-May and September-October, a long total-drought period from December through March and a less rigorous one from June to October.
Intense potential evapotranspitarion is also registered at this zone, ranging from 1,500 to 2,000 mm a year.
This zone can be sub-divided into two areas:
b. Mountainous Humid Zone:
Located to the north and at a higher location than the mountainous semi-arid zone. Annual rainfall amounts to 1,300 mm, with altitudes ranging from 600 m to 1,385 m asl.
It has a long rainy season from April to November. The remaining five months are relatively dry (December to March). Its geological composition consists of superficial calcareous massifs lying on a basalt layer, which occasionally surfaces at the depressions in the basin. Laterite soils.
The carbon dioxide-laden rainwater dissolves the calcareous layer, forming gorges and underground caves, which seem to constitute the reservoir for the recharge of the natural springs existing at the flatland area: Digue, Maneville, Lagon, Trou Caiman, etc.
SOCIO-ECONOMIC SITUATION
The official surveys indicate 58 human settlements in the area, with a considerably greater concentration in the low lands, where density reaches up to 400 inhabitants per square kilometer, while density at the mountainous area amounts to only 158.
Population growth rate is 2.1%.
These figures point to the great anthropical pressure on the region and which, logically, should entail the eventual depletion of the natural resources, —particularly forest resources— on account of the fact that one of the most important activities in the area is the production of charcoal and timber.
Agriculture is of the subsistence type, with rice, potatoes, sugar cane and various vegetables in the lower-altitude flood-prone areas.
In the higher semi-arid areas there are sorghum and maize crops.
The farmers and fuel gatherers have been left to their own resources, with no technical or economic assistance from the government or from other institutions, with the sole exception of a recently-started assistance of an AID program. It is in light of this that the ability of these farmers to carry out a rational exploitation —over many years— of the existing Prosopis juliflora forests is striking, enabling them to survive without destroying the resource.
The farmers have had a remarkable ability to manage these forests just as well as a group of foresters could, thereby keeping the resource intact as a supplier of charcoal, fuelwood, timber and other resources for subsistence.
A1 = Plains semi-arid zone
A2 = Mountainous semi-arid zone
B = Humid mountainous zone
Map of the great ecological zones.
Thomazeau watershed.
The management of the natural stands of Prosopis juliflora is carried out by thinning and clearcutting given plots.
In the thinning process, the shoots with greater diameter are selected for felling, growing from original stumps which in certain cases may reach considerable size, on account of their old age.
They never fell shoots less than 20 cm in diameter.
There are certain areas with large-sized trees which are felled to make wooden planks. Stumps are left at 50 cm height to permit the growth of new shoots, of which only the more vigorous ones are left to grow, normally no more than 4 or 6, typically 2.
The regeneration capacity of a natural forest under this type of management is of about 10 years, with clearcutting distributed on plots not larger than 5 ha in area.
The clearcut logging methods are highly primitive, using only axes and transporting the logs in oxen carts.
The products obtained have two main destinations: planks for construction and carpentry, and poles and beams used as railway sleepers and in housing construction.
The waste is used as fuel by the local inhabitants, leaving the larger-sized pieces for charcoal production in traditional kilns.
Planks are obtained in primitive sawmills, where the logs are hand-sawn.
All this timber is sold at the area of Port-au-Prince, primarily to the Sugar Company, which acquires sleepers for its railroad.
Considering the critical situation of total devastation of the natural resources prevailing in Haiti, and taking into accoutn that over 85% of the population in Thomazeau cannot read or write and lives under very precarious conditions, this case is even more surprising. It shows an example of the management of a forest resource derived, doubtlessly, from a natural conservation criterion, which has prompted these farmers to conserve their resource. This criterion has not been observed anywhere else in Haiti, even in areas socially and economically more advanced.
Recently clearcut Prosopis forest.
Thomazeau: Railway sleepers from Prosopis for the Sugar Company railroad at Port-au-Prince.
