Panel 2: Ecology (Contd.)

PROSOPIS SPECIES DEVELOPMENT PROGRAMMES IN INDIA

K. D. Muthana
Chief Technical Officer (Forestry)
Central Arid Zone Research Institute
Jodhpur, India

INTRODUCTION

In Indian arid and semi-arid regions, a few exotic species of Prosopis have been introduced at the Central Arid Zone Research Institute Farm: P. juliflora, P. tamarugo, P. alba and P siliquastrum. One of the most valuable trees of the desert regions is Prosopis cineraria (MacBride), an indigenous species. Among the exotics, P. juliflora (Swartz D. C.) has been found suitable and adopted tree species in the desert regions, which provides fuel in abundance to the local population.

P. juliflora (Swartz) D.C. is a thorny, large crowned evergreen to semi-evergreen tree having deep as well as lateral root system. It grows up to 10 meters height depending on the type of soil, in arid climate. It was introduced in India in 1877 (Sind) and, later on, in many parts of India. It was again introduced in 1913 by the then ruler of Jodhpur State in many arid and semiarid parts of Rajasthan, with great success. The State government at the time declared this species as a “Royal Plant” in 1949, and exhorted the public to protect it and encouraged large scale plantations of this species. Later on, it proved to be the most versatile plant for afforestation of the shifting sand dunes, coastal sands, eroded hills and river margins, saline terrains, dry and degraded grasslands and wastelands where rainfall is scanty and erratic. It grows well in regions with 150 to 600 mm rainfall. It is fast growing, it reproduces well by coppicing and through root suckers. It is seen growing profusely on vast areas of wastelands and grazing lands mainly through seeds encapsuled in the droppings of goats and sheep. The quality of feed it supplies through pods and the good quality fuelwood it produces in short rotations, is a boon to the desert dwellers. This species always remains in great demand in most parts of the arid and semi-arid regions. Though it is an introduced tree species, it is now well adapted to the Indian dry zones.

The usefulness of this species in afforesting arid and semi-arid areas has long been recognized by foresters and tree lovers. It can be grown as a tree, shrub and as a hedge. It is a useful sand binder and has established its identity as a good and fast growing species for reclamation of degraded grasslands and wastelands, where no other valuable tree species would easily grow. It is drought resistant and tolerates mild frost, having the ability to withstand adverse conditions. Argentinian and Mexican types are reported to be frost hardy but the Australian type is susceptible to frost at seedling stage. The Peruvian type has been found to be more sensitive to frost than the Australian one. Therefore, choice of provenance is of great importance before large scale afforestation programmes are designed.

SEED EXTRACTION

Extraction of seeds from the pods is rather difficult and a few methods are detailed below:

The gummy seeds with their inner cover intact are soaked in a solution of 0.1 N HCI for 24 hours. They are subsequently removed from the solution and again soaked in clean water for an hour and then dried in the sun. While drying, the segments start opening and they are slightly pounded to remove the outer coat to obtain clean seeds. Weevils often damage the seeds, hence pods/seeds collected may be fumigated before storage. There are about 10,000 to 20,000 seeds in one kilogram.

PRETREATMENT

i) The pods are generally broken into smaller segments to have one seed in each of them. These segments are soaked in water for a period of 24 hours and then rubbed with the hands to remove the outer coat. This method will give out seeds with a fibrous seed coat which is not easily separated. These segmented seeds are sown at site or in the nursery beds.

ii)The simplest and most commonly adopted method is to feed goats or sheep with the entire pods with seeds, and the seeds ejected by these animals during rumination or which have passed through their digestive systems are collected for sowing. Such seeds embedded in the droppings germinate quicker and give higher germination.

iii)If clean seeds are required for experimental sowing, the best method is to separate them from their inner fibrous seed coat. After soaking them in water (tap or well water) overnight they are sown to get good germination.

iv)To remove the dormancy due to the hard seed coat, the broken pods are soaked in commercial grade concentrated sulphuric acid for 15 to 20 minutes and then washed thoroughly in cold (tap or well) water. Seeds thus treated germinate in about 4 to 6 days with 80 to 90 percent germination.

PLANTING TECHNIQUE

Nine- to ten-month-old seedlings or pre-sprouted stumps are planted in pits of 60 cm³ at the required spacing. The planting programme should start with the onset of the monsoon. After transplanting, saucer shaped depressions of 1 m diameter having 15 cm depth near the stem of the plant may be provided in flat areas. On slopy areas, 15-cm-high crescent shaped ridges lying across the local slope may be provided to harvest the runoff water for boosting the growth of the plants. Weeding and soil working is necessary and should be done twice a year and continued until the plantation is about 3 years old.

In case of no rains after transplanting, supplementary watering should be provided at 9 liters per plant at fortnightly intervals for proper establishment. If well distributed rains occur after planting, watering is not necessary until March or until the plants show signs of wilting.

If Prosopis juliflora seedlings are to be raised on a field boundary as live hedge or as wind break, pretreated seeds may be dibbled 15 to 30 cm apart in lines during the rainy season to get a thick row of vegetative cover.

If the objective is to protect the avenue plants from biotic interferences, seeds of Prosopis juliflora may be sown in trenches around the avenue plants 1.5 m away from the main planting pit. The seedlings of this species grow fast and vigorously providing adequate protection to the avenue plants in the initial stages. When the avenue plants are established and reach a height of about 2 to 3 m, they may be felled for fuel.

GROWTH ATTRIBUTES

Prosopis juliflora is a fast growing, drought-hardy tree, most suited for arid and semi-arid regions. The only setback is that leaves of P. juliflora are not edible, although they have high crude protein contents.

Palatability and a chemical analysis of the leaves are furnished in Table 1.

TABLE 1

Palatability and chemical analysis data for Prosopis juliflora and Prosopis cineraria. (The figures represent percentage of the constituents on dry weight basis)

The merits and demerits of Prosopis juliflora are as indicated below:

1. Fast growing, drought-hardy species suitable for arid and semi-arid regions.
2. Coppices well.
3. Good fuel wood with 8050 Btu as caloric value.
4. Good quality charcoal is prepared.
5. Good for raising on field boundaries for protection from cattle entry.
6. Plantations can be raised by direct seedling/transplanting seedlings/pre-sprouted cuttings and stumps.
7. Leaves have no fodder value.
8. Extraction of seeds is difficult from the pods.
9. Dried pods are pound nicely and used for human consumption during famine.
10. Gum of this species is used for sizing of paper, calico printing, cosmetics, etc.

It may be emphasized here that Prosopis juliflora (Israel origin) has performed better with respect to all growth parameters when compared with Acacia tortilis (Israel) and other indigenous trees under similar environmental conditions (Table 2).

TABLE 2
Comparative growth of Prosopis juliflora (Israel)

Studies on pre-sprouted stumps of Prosopis juliflora revealed that seedlings raised from stump cuttings grow rapidly. Various sizes of stumps from 1 ½ year old seedlings of Prosopis juliflora were grown in the nursery beds. Stumps of 1.5 cm collar diameter, 2.5 cm shoot length having 17.5 cm length of root portion have been found to be of optimum size for raising stocks. These stumps were transplanted in galvanized iron tubes and were kept under identical environmental and watering conditions in the nursery. It was also observed that under nursery conditions smaller stumps having smaller collar diameter and shorter root length reduced the sprouting period compared to the stumps of larger collar diameter and longer root length. When compared with the effect of size of presprouted stumps on their subsequent growth in height after seven years of transplanting, it was observed that the initial gains in growth in the nursery did not maintain their superiority over other treatment combinations after planting in the field (Table 3).

TABLE 3
Mean growth in height (cm) of presprouted stumps after seven years of out planting

For predicting minimum sprouting period of a stump of given root length or collar diameter, the following prediction equations were worked out:

1. y-20.26-0.031 x
   where “y” is number of days required for sprouting and “x” is length of root in cm.

2. y-17.6-2.53 z + 1.53 z²
   where “y” is number of days required for sprouting and “z”, the collar diameter of stumps in cm.

It has been therefore concluded that Prosopis juliflora stumps of 1.5 collar diameter and 17.5 cm root length are the most suitable for presprouting in the nursery. Their field establishment and subsequent growth in height remained unaffected by their sizes.

Performance of Prosopis juliflora with regard to various growth attributes is commented below.

Seed germination studies: Seeds of Prosopis juliflora sown on 22nd August continued to germinate until 8th September giving 67 percent germination. It was noticed that germination commenced from the fourth day. Maximum germination was recorded from sixth to ninth day.

Regarding the growth rate of shoot and root, maximum growth was recorded during the second week. In the seedling stage, growth of shoot, root, and the development of secondary roots was recorded from the seventh day to 75th day of growing period. Nodulation was initiated as from the sixth week in P. juliflora. A greater number of leaves were recorded in the tenth week (75 days).

Studies to determine the optimum age of exploitation and fuel yield of P. juliflora were carried out on 4 different habitats of different rainfall zones viz., Sardar Shahar (268 mm), Jhunjhunu (395 mm), Gadra Road (285 mm) and Bikaner (285 mm) (Table 4).

TABLE 4
Average fuel yield per tree of Prosopis juliflora in kg (m) and percentage standard error (cv) as affected by different ages and habitats

Note: Figures in parenthesis denote the number of trees harvested.

Sig.: Significant
N. Sig.: Not significant

There were wide variations in the fuel yield, both with respect to age of the tree and to the habitat, and there were significant age differences in all the habitats. The habitat differences were significant in 4-, 5-, 8- and 10-year-old trees, and it was also inferred that with the increase in age, the tree to tree variability decreased. A study on mean annual rainfall of these habitats indicated that the difference in fuel yield between the habitats followed the pattern of increase in the rainfall from west to east.

It was further seen that fuel yield increased with the age of the trees and has a correlation with the climatic factors.

Data on growth attributes viz. diameter at breast height (cm), and height of tree (m) as affected by age of tree and habitat, are presented in Table 5.

There were wide variations in DBH and heights of trees of different ages belonging to different habitats. A comparison of data in Tables 4 and 5 revealed that trees of higher DBH produced higher fuel yield whereas tree height did not influence its fuel yield. The habitat x age interaction was significant for both parameters. It was also found that for predicting fuel yield, DBH alone is sufficient. The equation y = 2.10 + 5.08 x, where y is the yield in kg and x is the DBH in cm, can be used for prediction purposes. It was also indicated that with a unit increase in DBH, the fuel yield increases by about 5 kg for the age range of the trees.

TABLE 5
Average (m) and percentage standard error (cv) values of DBH (cm) and height (meters) per tree

A replicated study to find out the most economic and easiest method for the establishment of P. juliflora in plantations on the wastelands of western Rajasthan was carried out, using the following scheme:

Prior to sowing at those two sites, seeds were soaked for 40 hours in tap water. Inside the fenced area, seed germination was observed from the fifth day in all the treatments. The germination of seeds continued for 67 days, with the maximum occurring (Table 6) within the first 30 days, with more than 50 % in “i” and “ii” treatments and about 40 per cent in treatment “iii”, and negligible thereafter under fenced area. The data also revealed that there was no significant difference between treatments “i” and “ii” but between treatments “i” and “iii” and “ii” and “iii” significant differences were observed, indicating that placing seeds of Prosopis juliflora beyond 2 cm depth is not desirable.

In the unprotected area, seed germination was noticed from the fifth day of sowing, but it was 28 per cent in “i” and “ii” treatments and 20 per cent in “iii” 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 30 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 plantation of P. juliflora or 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.

TABLE 6
Mean seed germination data for P. juliflora inside fenced area

* Significant at 5% probability level

The provenance-fertilizer trial of Prosopis juliflora indicated that seeds of Israel and Chile lines were superior to those from other sources, as evidenced from the growth attained over 12 years at Jodhpur, (Table 7).

Regarding the nature and role of germination inhibitors present in leaves of Prosopis juliflora, it has been observed that the large quantities of leaf litter accumulated beneath the tree contain inhibitors which though water soluble do not seem to accumulate in the soil in high concentration. If the seeds of other species fall on the thick layer of leaf litter, they rarely germinate and establish, due to direct action of these inhibitors on the germination and growth processes. Seeds present just below the soil surface may show some germination, but this again is restricted due to the action of inhibitors on their growth due to mechanical hindrances of the leaf litter. Effects of shade, competition for moisture, and the influence of certain other factors may also have indirect effect on the establishment of plants.

TABLE 7
Provenance cum fertilizer trial on P. juliflora
(Age: 12 years) (Mean growth in height in cm)

Fertilizer treatment on hectare basis

To a certain extent, the author, after a 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 drooping branches, which normally cleans the ground floor completely. Due to the mechanical action of these branches, whatever seeds sprout, are either damaged or swept away from the vicinity of such low branched trees. Under tall and straight stems, lush growth of grasses, e.g. Cenchrus ciliaris and Aristida spp., have been observed on different habitats. Furthermore, the selection of such tall straight types of Prosopis juliflora would also be suitable for silvo-pastoral programs.

UTILITY

Flowers produce nectar for good quality honey. Pods are eaten freely by the livestock. Ripe pods are of high nutritive value, containing 12 to 13 per cent crude protein and are high in sugar and nitrogen content. In Mexico, ripe pods are made into coarse flour and baked after removing the seeds, fermented and brewed into weak beer.

This species is ideal for afforestation of wastelands, marginal uncultivable lands, shifting sand dunes, and also as live hedges along field boundaries. It is a very good coppicer and also propagates from the root suckers.

Wood is hard, durable and has good fuel value (8050 Btu/lb). Good quality charcoal is prepared from the branches and main stem. It can produce about 100 kg fuelwood per tree in about 10 years rotation 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 economic value of this tree.

PESTS AND THEIR CONTROL

Rodents and white ants are the main pests for seeds and seedlings of this species. Rodents eat up the tender cotyledon and the young seedlings in the initial stages. Rodents can also ruin older plantations by gnawing the roots below the ground level. Similary, white ants are also equally destructive to the younger as well as older plantations.

Unless their menace is properly and timely checked, all efforts to raise the plantation by direct seeding and transplanting would be futile. The precaution to be taken from the rodents is by prebaiting and destroying them by 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 the seedlings, with two successive repetitions at fortnightly intervals.

GENERAL

Some scientists are of the opinion that Prosopis juliflora, if raised on large scale, would become a weed in due course, 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 in wastelands where annual rainfall exceeds 500 mm and if the plantation is raised along the river banks. In areas where rainfall is erratic, uncertain and ranges between 250–350 mm. This species is a boon, as no other tree would grow well under such harsh environmental conditions, except Acacia tortilis. These conditions often prevail in arid and semi-arid environments, and when the fuelwood requirements of the local population are taken into account, the preferences are for fast-growing, drought hardy tree species. This species can hardly encroach upon the surrounding areas under the inadequate moisture conditions prevailing in dry regions. Furthermore, Prosopis juliflora has very good coppicing potential. Unless some alternative useful species for the arid and semi-arid regions is found, Prosopis juliflora, which is the most versatile plant for such harsh environmental conditions, should be given priority rather than condemning.

PROSOPIS CINERARIA (MACBRIDE)

Prosopis cineraria (MacBride) is an important indigenous species having both fuel and fodder value, with the only setback of being a slow growing tree. It attains a height of 3–4 m in about 10 years under low rainfall conditions. It was, therefore, felt necessary to select some plus trees out of the naturally grown stands in order to offset this disadvantage. It has been found that seeds from a few selected trees have produced very fast growing seedlings. Further work on genetic improvement is in progress.

The establishment rates and mean growth in height attained over six years by the five plus trees collected from Jodhpur (350 mm) and Bikaner (285 mm) are presented in Table 8.

TABLE 8
Performance of plus trees of Prosopis cineraria from Jodhpur and Bikaner

The data revealed a wide genetic variability in mean height, even within the same line, and hence further screening to select a fast growing line is possible. The results also indicate that the height growth attained over 6 years by J-3, J-4 and J-5 Jodhpur provenance and B-2 and B-5 of Bikaner provenance are maximum.

Further attemps to raise seedlings by tissue culture and air layering from the plus trees have been successful, but raising seedlings by branch cuttings have failed.

From the fuel yield study carried out, it was revealed that Prosopis cineraria diameter at breast height (DBH) is highly correlated with fuel yield determination, viz.,

y = 0.2596 x^2.2437

where: y = total fuel yield (in kg)
x = diameter at breast height (in cm)

SOIL PHYSICAL CONDITIONS UNDER P. CINERARIA

The mechanical composition of soils under Prosopis cineraria has shown an increase in silt and clay content up to 120 cm depth, while it was up to 90 cm only in open field. Similary higher moisture content was observed under P. cineraria and minimum under P. juliflora. The moisture depletion pattern at different depths showed higher rates from deeper layers under P. cineraria, while it was higher nearer the surface under P. juliflora. This shows that P. cineraria does not compete with perennial and annual flora under its canopy, mainly due to its deep tap root system (Lahiri, 1980).

SOIL FERTILITY CONDITIONS

The leaf litter from P. cineraria, as organic matter, improves the nitrogen status of the soil. The pH value is slightly lower under P. cineraria than in open field, and the E.C. values showed 0.01 mmhos/cm under P. cineraria, while it was 0.22 mmhos/cm under P. juliflora and 0.20 mmhos/cm on open field conditions. The data (Table 9) presented show the depthwise distribution of organic matter and macro and micronutrients in the soils under P. cineraria, P. juliflora and open field.

An increase of about 150 percent in organic matter has been observed in soils under P. cineraria, as compared with P. juliflora and open field conditions. The increase in organic matter under P. cineraria appears to result from higher litter fall, i.e. 68 g/m² in comparison to 23 g/cm² under P. juliflora. There is increase in phosphorus and potassium content in soils supporting P. cineraria over P. juliflora and open field; this is more significant in surface soil.

TABLE 9
Available macro and micro nutrient contents in soils

Available Zn, and Cu contents were also higher in soils under P. cineraria, while soils under P. juliflora showed higher Fe contents. Almost the same trend was observed when leaf litter was analysed for chemical composition (Tables 10 and 11).

TABLE 10
Chemical analysis of soils just below the leaf litter of P. cineraria and P. juliflora

TABLE 11
Chemical composition of leaf litter of P. cineraria and P. juliflora (percent of dry weight basis)

Better soil fertility beneath Prosopis cineraria suggests higher growth and activity of soil micro-organisms contributing to the building up of the fertility. The population of nitrifying bacteria was also found to be fairly higher under P. cineraria than under P. juliflora.

UTILITY

P. cineraria has been recognised as a mayor economic species among the flora of arid regions. Almost all parts of the tree find some use or the other. Wood is the main source of fuel wherever P. juliflora is not available. The leaves are annually lopped and stored as livestock fodder. From a 30-year-old tree, the dry fodder yield would be about 4–5 kg/tree but a well grown tree would yield about 25–30 kg/tree. Tender pods are collected and stored to use as vegetable; a tree of about 30 years of age would yield 5 to 8 kg/tree of tender pods on air dry basis. Ripe pods are eaten by the farming community just as any other dried fruit. Seed yield of a 30-year-old tree would be about 2–3 kg under 350 to 400 mm annual precipitation. The bark of the tree is powdered into flour and made into cakes for human consumption during famine periods. The bark is also used for leather tanning and also other local medicinal use, such as for treating scorpion bites, snake bites, etc. Roots are excavated and used as handles for agricultural implements. The gum of the tree is used by local people for making sweet preparations.

Trials on Prosopis tamarugo, P. alba and P. siliquestrum were carried out in 1976, 1981 and 1981 respectively. Their mean growth in height as of March 1984 was 3.5 m for P. tamarugo (1978); P. alba (1981) 1.6 m, and P. siliquestrum (1981) 2.3 m. Their performance has been very good under the Indian arid conditions and efforts to introduce P. tamarugo on a big way in some of our saline areas for reclamation as well as a fodder resource are in progress.

In most of the drier parts of India, several exotic species of Prosopis viz., P. glandulosa, P. argentina, P. nigra and P. velutina were introduced in the early nineteen forties, but none could beat the performance of P. juliflora var juliflora, with the result that P. juliflora var. juliflora has been successfully introduced on all the afforestation programs in India, mainly on barren sandy areas, refractary sites with scanty soil having sand stone substratum, and also on the saline areas.

REFERENCIAS

AGGARWAL R.K. 1980. Physico-Chemical status of soils under Prosopis cineraria — CAZRI monograph No. 11 on Prosopis cineraria: 32–37.

BHIMAYA C.P., KAUL R.N. and GANGULI B.N. 1965. Studies on pre-sprouted stumps of Prosopis juliflora. Ann. Arid Zone 4 (1):4–9.

BHIMAYA C.P., JAIN M.B., KAUL R.N. and GANGULI 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 Proposis juliflora Sci & Cult. 27 : 489–490.

KAUL R.N., GOSWANI R.P. & CHITNIS B.K. 1964. Growth attributes for predicting pod and seed yield for Prosopis spicigera. Sci. & Cult. 30 (6): 282–285.

LAHIRI A.N. and GAUR Y.D. 1969. The nature of germination inhibitors present in leaves of Prosopis juliflora. Proceedings of the National Institute of India 35 : 60–71.

LAHIRI A.N. 1980. Prosopis cineraria in relation to soil water and other conditions of its habitat. CAZRI, Monograph No. 11 on Prosopis cineraria, 38–44.

MUTHANA K.D. 1980. Improved techniques for tree plantation in the arid zone. Technical Bulletin No. 2, CAZRI, Jodhpur; 1–22.

MUTHANA K.D. and ARORA. 1979. Acacia tortilis (Forsk), a promising fast growing tree for Indian arid zones. Technical Bulletin No. 5 CAZRI, Jodhpur: 1–19.

MUTHANA K.D. 1980. Silvicultural aspects of Prosopis cineraria. CAZRI Monograph No. 11 on Prosopis cineraria: 20–24.

MUTHANA K.D. & ARORA G.D. 1984. Prosopis juliflora (Swartz), a fast growing tree to bloom the desert—CAZRI, Monograph No. 22.

VASAVADA P.K. and LAKHANI B.P. 1973. A note for obtaining clean seeds of Prosopis juliflora from pods through chemico-mechanical method. Indian Forester 99. 163–165.

FAO PROJECT ON GENETIC RESOURCES OF ARID AND SEMI-ARID ZONE ARBOREAL SPECIES FOR THE IMPROVEMENT OF RURAL LIVING

Christel Palmberg
Forest Resource Division, Forest Department
FAO, Rome

BACKGROUND

While the importance of preserving and using the existing variation in nearly all of the tree species employed in large scale industrial plantations is recognized as essential, there is still little or no information available on the intraspecific variation of a great number of tropical species which are increasingly receiving widespread attention as suppliers of goods and services for rural communities.

In the Fourth Period of Sessions in 1977, the Board of FAO Experts on Forest Genetic Resources gave particular relevance to these multiple use species, previously granted little attention.

The Board compiled a list of priority species, stressing primarily tree species providing fuelwood in arid and semi-arid lands, where the growing pressure from human population and domestic animals, added to the fluctuations in the meteorologic regimes in the world, have led to a rapid deterioration of the ecosystems and genetic depletion of actually or potentially useful species.

Basing on recommendations from the Board and financial assistance from the International Board on Phytogenetic Resources, the Forest Department of the FAO started a project in 1979 on conservation and improved use of genetic resources of tree species to raise living standards in rural areas, focusing primarily on fuelwood producing species. After an initial stage consisting of a field survey of the requirements and possibilities of such a project, a second stage — execution— was initiated in January 1981.

GOALS

The main goal of the project is to gather data and genetic material for conservation and evaluation purposes, with the final aim of making a better and more rational use, on a stable basis, of the existing genetic resources of importance for rural communities as a source of energy, food, fodder, shade and shelter in tropical arid and semi-arid regions. The project aims, as well, at contributing to the establishment of a self-sufficient network of centers dedicated to seed collection and conservation from multiple use tree species.

Eight countries are officially cooperating with the project at the present time (Chile, India, Mexico, Pakistan, Peru, Senegal, Sudan and Popular Democratic Republic of Yemen). Australia and Israel, within their own areas, are also collecting seeds. All exploration, collection and evaluation activities are in the hands of local research institutions or national forest sevices.

To avoid duplication, FAO coordinates its work with the Centre Technique Forestier Tropicale and the Commonwealth Institute, which have also their own seed collection programs from arid and semi-arid tree species, and collaborates closely with the Danish Forest Seeds Center, Denmark, and the Kew Gardenia, England, which help in the handling, storage and distribution of the seed lots collected by the participating countries.

PROJECT STRATEGIES

The fruitful and sustained use of a resource requires botanic and genetic research, and the collection of seeds for their evaluation and conservation. The assessment or evaluation helps identify the potentially useful species, whereafter the economic or social values of the species and provenances included can be explored.

In situ or ex situ conservation helps preserve the actually or potentially useful strains for the future. Both strategies complement each other, and, whenever possible, should be attempted simultaneously.

The FAO Project, in addition to the basic stages of (i) surveying, (ii) collection, (iii) evaluation, (iv) conservation, and (v) use, also includes dissemination of the information gathered. Six handbooks on Acacia and Prosopis taxonomy and seeds are part of this activity, as well as a progress report of the project published in “Unasylva” and “Forest Genetic Resources Information”, etc.

Also included is a training item: paratechnical national courses at the participating countries and, of course, the overall coordination by the Forest Department of FAO.

ACTIVITIES IN 1981–1984

Collection

To date, the participating countries have collected some 150 seed lots from Acacia, Atriplex, Cercidium and Prosopis.

The amount of seeds collected varies from 0.5 and 10 kg per provenance. As seed availability depends on biologic factors outside the control of the collectors, some seeds will have to be collected from other areas in order to complete the representation of the natural range of the species involved.

Seeds are collected, whenever possible, from about 50 mother trees, representative of the different strains existing in the population. A standardized data sheet (Appendix) is filled out for each lot, stating the exact location, associated species, characteristics of the collected trees, etc.

Evaluation

During 1983, seed lots were distributed to all participating countries for their standardized evaluation.

To this end, a paper on trial establishment and management, and the features to be assessed, has been prepared.

After a second seed dispatch to the participating countries, experimental lots will be distributed to other countries interested in their evaluation.

Conservation

Part of each seed lot will be stored under sub-zero conditions for long term conservation. Unlike agricultural species, which are normally conserved by storing the seeds, forest tree and shrub conservation is generally performed through in situ or ex situ conservation stands; consequently, both strategies shall be employed in this project.

To provide a solid basis for these activities, it will be important to count on accurate knowledge regarding the range and intra-specific variation of the species, based on the surveying and evaluation stages. This knowledge will make it possible to improve our conservation stands network, as well as our sampling for genetic material collection for ex situ conservation.

Utilization

As knowledge becomes available on seed strains and provenances best suited and adequate for well-defined environmental conditions, the focus will be gradually shifted from experimental plots to wider use of the seeds.

Although bulk supply of reproductive material aimed at large scale planting will continue to be in the hands of governmental or commercial institutions, future assistance to other countries is considered, to help them in the establishment of conservation stands and local seed selection and production.

The advantages likely to be obtained through genetic improvement are considerable and long lasting, providing the improvement programs are carried out properly.

Genetic selection and improvement must be carried out using species well adapted locally and with a broad genetic base, so as to leave a margin for selection, and performing crossbreeding among non-related individuals. The potential benefits are considerable. It is very important to realize that the small experimental plots established with the primary purpose of undertaking species and provenance trials, on account of their relatively small size, should never be used as the sole base for selection and continuation of improvement programs, although part of the genetic material selected at those plots may be employed to enrich future populations in a genetic improvement program.

CONCLUSIONS

The overall goal of the FAO and its Department is to help the member countries meet the basic needs of their rural communities and to ensure general progress. Concurrent with this policy, the genetic resource programs under way are assisting the poverty-stricken rural populations, and intend to encourage the use of well-adapted genetic material, hardy and apt for forests, windbreaks, fodder production, land reclamation, etc.

Maximum priority is given to the conservation and evaluation of existing tree and shrub forest masses currently endangered or facing genetic impoverishment, but which adaptation to the prevailing environmental conditions and acceptance by the local populations are unquestionable; and to the establishment of systematic trials on species and provenances whereby the local species can be compared to the introduced ones under uniform management conditions.

The FAO project under way, focused on arid and semi-arid lands, is part of a network of similar programs coordinated by the Forest Resource Division of the FAO. The project has gained increased acceptance and importance since the beginning of its operational stage. An incipient but enthusiastic network of institutions ready to exploit their resources on a stable basis, and to continue supplying material of known genetic origin and good phisiological quality, has already been established to meet both their own needs and those of countries with similar environmental conditions. They will also have the possibility of providing assistance to other developing nations to undertake exploitation, conservation, collection and evaluation programs to benefit rural communities depending on rapidly depleting resources.

FAO is acting as a catalyst, but the achievements and findings are the result of the work of the participating countries.

Prosopis chilensis in Argentina. This is supposed to be the largest algarrobo in the world. (Photo D. Huss.)

REFERENCES

FAO 1975: Methodology for the Conservation of Genetic Forest Resources. FO:MISC/75/8. FAO, Rome.

FAO 1977: Informe de la Cuarta Reunión del Cuadro de Expertos de la FAO en recursos genéticos forestales. FO:FGR/4/Rep. FAO, Rome.

FAO 1980: Recursos Genéticos de Especies Arbóreas en las Zonas Aridas y Semiáridas: estudio sobre el mejoramiento de la vida rural en América Latina, India, Asia Sudoccidental y Africa. FAO, Rome.

FAO 1980: Proyecto FAO/IBPGR sobre recursos genéticos de especies arbóreas productoras de leña para el mejoramiento de la vida rural. Información sobre recursos genéticos forestales N^o 10, FAO, Rome.

FAO 1983: Handbook on Acacia seeds. FAO, Roma.

FAO 1983: Handbook on collection, handling and storage of Prosopis seeds. FAO, Rome.

FAO 1983: Handbook on taxonomy of some Acacia species. FAO, Rome.

FAO 1983: Handbook on taxonomy of some Prosopis species in Latin America. FAO, Rome.

FAO 1983: Handbook on insects attacking Prosopis seeds. FAO, Rome.

FAO 1983: Handbook on insects attacking Acacia seeds. FAO, Rome.

FAO 1984: Project on insects attacking Acacia seeds. FAO, Rome.

PALMBERG C. 1980: Principios y estrategia para el mejor aprovechamiento de los recursos genéticos forestales en: Mejora genética de árboles forestales. Estudios FAO: Montes N^o 20. FAO, Rome.

PALMBERG, C. 1981: Un acervo genético leñero en peligro. Unasylva 33 (133): 22–30.

APPENDIX 1

Fao Project

DATA SHEET: SEED COLLECTION

Detailed location:		Collection Ref. No.:......................................................................................
		Species:.........................................................................................................
		Country:.........................................................................................................
		Province/state:....................................................District.............................
		Lat.:...............°................'Long.:................°................'Alt.:................m
		Topography: Flat/Hilly
			Slope: Steep/intermediate/soft
			Soil: Deep/shallow/intermediate
				Drainage:.........................................................................
				.........................................................................................
				Presence of stones:........................................................
				Texture.............................................................................
				.........................................................................................
				pH: Acid/Neutral/Alcalyne

Rainfall: Annual Mean.........................mm; Rainy months:.........................; Dry months:.........................
Temperature: Annual mean:.....................°C; Max. mean:.....................°C; Min. mean:.....................°C
                         Frost:................................. days per year

Stand: Natural: Grouped/Open            Thin/Dense
Young/Middle aged/Old

Plantation: Age:......................years       Height:......................m;       Diameter:......................cm
Provenance:......................................................................................................................................

Associated species:........................................................................................................................................................................................
Shape: Straight/Acceptable/Twisted
             Crown: Flat/Narrow/Medium/Wide            Stem: Only/Multiple
Seed Yield: Scant/Medium/Abundant
Seed collection: No. of trees:.....................kg.
Minimum spacing: ..........................................................................................................................................................................................
Notes:...............................................................................................................................................................................................................
...........................................................................................................................................................................................................................
...........................................................................................................................................................................................................................
Collection date.....................................................................................................

................................................
Officer in charge