Panel 3: Botanics (Contd.)

MORPHOLOGICAL DIVERSITY IN PROSOPIS CHILENSIS POPULATIONS AND EVALUATION OF ITS GROWTH IN PLANTATIONS AT REGION IV

Bernardo Contreras
National Forestry Corporation
La Serena, Chile

INTRODUCTION

Algarrobo (Prosopis chilensis (Mol.) Stuntz) is one of the arboreal species with interesting prospects for utilization in afforestation plans, under the extremely constraining ecological conditions found at Region IV.

The irregular and scanty rainfall and the degree of soil deterioration do not make it easy to select species suitable for use in this area. There are two alternatives to face the problem: 1) to introduce exotic species which performance and provenance suggest good adaptation probabilities, and 2) to study and develop indigenous species from the zone, assumed to be already adapted to those ecological conditions.

Aware of the degree of soil deterioration, the low availability of desirable plant species and the need to incorporate new areas into economic production, the National Forestry Corporation of Chile has endeavoured to collect data on various economically attractive species either native to this area or typical of arid regions.

Algarrobo fulfills the condition of being a native species adapted to the soil and climatic conditions occurring at the area. It still occurs at many areas, despite the intense exploitation which has depleted its numbers, and it is used intensively as a source of fuelwood and charcoal, or to harvest its fruit. This is the best background to support the utilization of this species in afforestation programmes.

Both at home and abroad, this species has major importance in land reclamation and arid and semi-arid land incorporation into productive uses. Its timber can be used in carpentry and flooring, in addition to its fuel value (2); pods have been consumed since ancient times by people native to its natural range (16); alternatively, collected and stored pods are used as animal fodder for two months a year, with a feeding value matching that of barley and maize (16).

Besides being a source of fodder for livestock and of wood for carpentry, algarrobo has considerable importance throughout the world as fuel in desert regions, as in these areas, according to IREN-CORFO and CIFCA (1978), consumption of energy derived from fuelwood is very high, 50% for cooking purposes and 35% for heating; in warm regions, the energy for cooking purposes amounts to 80–90%. This is vitally important now that fossil fuels are becoming increasingly scarce and expensive, as energy consumption grows concurrently with the population. Therefore, considering that the tendency is to obtain this energy from wood, fuelwood sources must be made available.

In its natural stands, this species shows variations in height, amount or presence of thorns, taste of the pods, pod yields and number of folioles (16); this coincides with what has been observed in the populations found at Region IV (10), where variations were observed in fruit size and shape, amount of branches and size of the crown.

This paper aims at the establishment of the degree of difference in the form, conductive to the identification of the morphologic species or morphotypes, to which end the analysis of main components will be used.

Considering the productive characteristics of the species and its adaptation to arid environments, the study of the polymorphism of the most relevant traits of individuals from different populations is very important, with the purpose of assessing the degree of significance of this diversity and identifying morphotypes suitable for future utilization in afforestation programmes with the species.

2. GENERAL DATA ON PROSOPIS CHILENSIS (ALGARROBO)

2.1 Brief Description

Algarrobo belongs to the family Leguminosae (Mimosoideae), genus Prosopis and species Prosopis chilensis.

It a fast-growing round-crowned tree; it reaches a height of 3–10 m; branches are flexuose, knotty and partly thorny; in young shoots strong thorns grow profusely; leaves are deciduous, uni-tri-yugate; petiole 1.5 to 12 cm long; leaflet 8 to 24.5 cm long; 10–29 pairs of folioles per leaflet; flowers racemose, usually greenish-white-yellowish in color; calix 1 mm long, petals 3 mm long, stamens 5–6 mm long; ovary pubescent; fruit a linear legume, compact, with parallel edges, yellowish, 12–18 cm long, 1–18 cm wide and 0.6 cm thick; mesocarp sweet, edible; brown oval-shaped seeds 6–7 mm long (2).

2.2 Range

Its natural range is very ample, and it occurs in Peru, Bolivia and the central-northern part of Chile; in the Argentinian Northeast it can be found in the provinces of Salta, Tucumán, Catamarca, La Rioja, San Juan, Mendoza, San Luis and Córdoba; in Southern Peru it occurs up to 2,900 m elevation. Looser (1962) gives a detailed historical range for this species, but confined solely to the province of Santiago and the surrounding area. According to this author, the southern border of its range would be located in the vicinity of the San Francisco station, at the former O'Higgins Province, presently Region VI; the eastern border: the Chacabuco Farm, Peldehue, Baños de Colina; the western border: Lampa, Pudahuel, Isla de Maipo. According to Reiche (1973), other sectors where the species occurs are located in the province of Copiapó, and its range extends from the Northern End to the Central Zone.

Other authors state that its natural range is from Atacama to Santiago (Central Zone) (7, 8).

2.3 Main Characteristics

2.3.1 Habit, growth and stem

The tree can reach 3–10 m in height (2) and up to 80 cm in diameter; under good conditions it growths fast; the stem is short and ramified from very near the base; the branches have generous knots where the thorns, leaves and flowers grow (7). Individuals with no thorns have been observed (16). The stem, which is yellow-greenish and smooth-surfaced when young, turns gray-reddish with age, with some ridges and cracks running the length of its bark (15). It is common to observe that a tar-like substance is exuded through folds in the bark, initially gray-brown and later, through oxidation, turning dark brown to black (15). Stumps sprout easily.

2.3.2 Flowers and Fruit

a) Flowers. They occur in cylindrical bunches (7), yellowish-greenish in color (17). Flowers are good bee fodder (15), are hermaphrodite and germinate by epigenesis (7).

b) Fruit. Fruit is an indehiscent legume with varying size and shape (15); ripe, its color is straw-yellow and is 12–18 cm long, 1–1.8 cm wide and 0.6 cm thick (2, 27); its mesocarp is granulous, sweet and with high nourishing value (2). It is for this reason that its pods are excellent food (17). According to Medina (1942), the fruit weighs an average of 10.40 g, with a maximum of 15 g and a minimum of 5 g. This same author published a paper in 1942 where he reported obtaining 6.17 liters of 51.9° ethyl alcohol from 35 kg of fruit. This means that from 100 kg he would have obtained 17.67 litres of 51.9° alcohol which, with subsequent rectification, would have yielded 9 litres of absolute anhydrous alcohol.

2.3.3 Wood

Its wood is dark brown, frequently with a purple hue; it is very hard and the vein is irregular, but easy to work (17). It has applications in carpentry, floors, and as poles and fuel (28).

2.4 Environmental Adaptations and Requirements

The elements helping a plant live under water stress are root dispersion, foliar morphology and physiological adaptations, which are complemented by stomatal opening, photosynthesis and biochemical changes (8).

Algarrobo, native to arid zones, has small leaves (microphylla), a very efficient adaptation to prevent overheating and, thereby, excessive transpiration (7).

According to Alfaro (1973), algarrobo presents distinct foliar absorption. Its roots penetrate deeply searching for the groundwater table (7), frequently reaching depths up to 10 m and, occasionally, even 20 m (16).

Usually they receive 200–400 mm yearly rainfall, but very well established individuals have been found thriving at places with rainfall below 75 mm. They normally tolerate 8–11 rainless months, and can easily withstand long droughts (16, 17).

This tree can stand very high temperatures, typical of desert zones; it is not adapted to cold weather and requires temperatures of around 27° C to grow well. Trees raised from seedlings have been reported to withstand temperatures as low as -5° C, but for very short periods of time (17). it requires substantial sunlight to develop well. In Northern Chile it reaches maturity at the age of 30–35 years, whereas in the Central Zone it takes 50 years to reach full development (19).

As regards it range in altitude, it is recommended to plant this tree between 340–1,200 m above sea level (asl), although in Peru it has been found growing at altitudes of up to 2,900 m asl.

It grows well on flat soils with little slope, where its roots can reach the groundwater table quickly. It normally grows on the flat lands, without reaching the foothills (7). According to Tinto (1974), in Argentina it shows similar soil requirements, preferably loose and deep soils, or stony-sandy soils.

3. MATERIAL AND METHOD

3.1 Studied Sites

The sites where the study was to be conducted were selected by making a field reconaissance of the areas with confirmed sizable algarrobo populations.

Four places were selected, as follows:

• Río Pama
• Monte Patria
• Corral Quemado
• Quebrada Marquesa

Sampling was carried out as a the second stage, including the delimitations of the above populations on Military Geographic Institute (IGM) charts, serving as a previous basis for subsequent populational charts.

3.2 Selection of Variables

Faced with both qualitative and quantitative traits, the latter were chosen as a matter of convenience in the method. These are known as metric traits.

Sokal and Sneath (1973) explain the convenience of taking at least two standpoints as reference when selecting traits in taxonomic practices: 1) to use all kinds of traits from all parts of the individual and from all the stages in the life cycle; 2) to use all the traits which vary within the study group and not solely traditional diagnostic traits.

It was determined that the traits or variables considered for the study would be extracted from various parts of the plant, such as the leaves, thorns, branches and fruit; likewise, the measurements made were focused in the assessment of the variations observed within the populations and among the populations, grouping them according to their position.

3.2.1 General variables

1. Total height
2. Height of ramification
3. Breast-height diameter (BHD)
4. Number of shoots
5. Crown diameter

3.2.2 Variables in a determined length of branch

6. Number of brachyblasts
7. Number of leaves per brachyblast
8. Dry weight of leaves (10 leaves)
9. Length of leaves (10 leaves)
10. Width of leaves (10 leaves)
11. Number of folioles (10 leaves)
12. Number of thorns
13. Length of thorns
14. Branch diameter (subdistal meter, i.e., at 1.5 m from the apex of characterized branch)

3.2.3 Fruit and seed variables

15. Number of pods per kg
16. Pod length
17. Mean pod width
18. Pod thickness
19. Number of seeds per pod
20. Fruit dry weight (pod)
21. Number of seeds per kg
22. Number of seeds damaged per kg

3.3 Sampling System and Trait Measurement

3.3.1 Sampling method

Data were obtained with a sampling method aimed at covering the whole population, for which purpose sampling strips were arranged, along with selecting those individuals within the strips which bore fruit.

3.3.2 Trait measurement

The methods used for measuring the traits are detailed below, indicating the instruments or materials used for the purpose:

General variables

1. Total height, measured from the base to the apex, using a hypsometer.
2. Height of ramification, defined as the distance from the ground level to the point where first branch or branches appear. Measured with a hypsometer.

3. Breast-height diameter (BHD), taken at 1.30 m above the ground in all those individuals branching out above that point. As no diametric meter was available, an indirect method with linear measuring tape was used, transforming subsequently with the formula:

   p = π × d

   

   d = diameter (cm)

   p = perimeter

   π = constant (3.1416)

4. Number of shoots: corresponds to the number of branches in the first ramification.
5. Crown diameter, corresponding to the average of two measurements of the crown projection area, made from north to south and from east to west, using a compass and linear measuring tape.

Variables in a section of a given branch

The following variables were measured in a given branch within a one hundred centimeter length at 50 cm from its apex (sampling unit), also labelled as subdistal meter.

6. Number of brachyblasts; corresponds to the number of leaf groups in this one-meter branch section.
7. Number of leaves per brachyblast. All brachyblasts in the one-meter branch section were considered, obtaining a sampling mean therefrom.
8. Dry weight of 10 leaves. This trait was determined from 10 leaves taken at random from the sampling unit, and heater-dried at 105° C for 24 hours and expressed as weight/10 leaves.
9. Leaf length; corresponds to the average of the 10 leaves taken, using a millimetric ruler.
10. Leaf width. This measurement was made with a millimetric ruler at the central part of the leaf, considering the folioles perfectly perpendicular to the rachis.
11. Number of folioles. The folioles of each leaf sampled were counted, computing a sampling mean.
12. Number of thorns; corresponds to the total amount of thorns in the one-meter branch section.
13. Thorn length. This trait was obtained by measuring each thorn in the one-meter branch section to compute the sampling mean.
14. Branch diameter 1.5 m from the apex, measured with a ruler.

Fruit and seed variables

About 100 g of fruit were collected from each selected tree, an amount determined from previous observations of Prosopis chilensis populations, where a decrease in fruit yields had been observed; i.e., this small amount insured the inclusion of trees with very low yields.

15. Number of pods per kg. The amount of fruit was weighed and the number of pods was counted; the number of pods per kg was subsequently extrapolated from this ratio.
16. Pod length. A measuring ruler was used, straightening the pods when they were too curled up. All pods sampled from each tree were measured, computing the sample mean therefrom.
17. Pod center width. All fruit collected were measured, computing the sampling mean therefrom.
18. Pod thickness. As in the above, all pods were measured to compute the sample mean.
19. Number of seeds per pod. The seeds were extracted from each pod and subsequently counted to compute the mean.

20. Pod dry weight. The pods were weighed when green (green weight - GW) and then heater-dried at 105° C and weighed again, to obtain the dry weight (DW), which was subsequently expressed as a percentage of the total weight or green weight, using the following algorithm:

    

    where: GW = green weight
    DW = Dry weight

21. Number of seeds per kg, obtained from the total amount of seeds extracted from the total sample, counted and weighed.
22. Number of damaged seeds per kg. This type of seeds is part of the total seeds in the sample. This bracket included seeds damaged by insects once they were formed, and those which, as a result of damage not specified in this stage, could not reach their final form. In the latter case assessment was visual. In the former type of seeds, there is some damage not visible to the naked eye, as the seed is not broken. A metallic straight edge was used to press the seeds against a hard surface; if damage was present, the seeds would burst open, unlike healthy ones, which would stay whole.

3.4 Analysis Methodology

The analysis of the morphological similarity among individuals was made by means of the Analysis of Main Components, which is an ordering method for reduced spaces, applicable to sets of metric traits, and consists of analyzing and representing the individuals in a multi-varying chart having as many axis as traits or descriptive characters available.

A number of quantitative data may be obtained with this method regarding the value of the projections derived, to outline the relations among traits as well as relationships among individuals.

A computer loaded with the ACOMP program was used to process the method of analysis.

4. RESULTS

The analysis was applied by parts in each of the populations of the survey, which were also taken as a whole for the overall analysis.

4.1 Variable Codes

The need of defining codes for the variables derives from the application of this methodology in a computer. The equivalence is shown below:

4.2 Río Pama Population Analysis

— Distribution of the 50 individuals into 10 classes and density chart illustrating the distribution made.

4.3 Monte Patria Population Analysis

— Distribution of the 50 individuals into 10 classes and density chart illustrating the distribution made.

4.4 Corral Quemado Population Analysis

— Distribution of the 50 individuals into 10 classes and density chart illustrating the distribution made.

4.5 Quebrada Marquesa Population Analysis

— Distribution of the 50 individuals into 10 classes and density chart illustrating the distribution made.

4.6 Overall Analysis

— Distribution of the 200 individuals into 10 classes and density chart illustrating the distribution made.

5. DISCUSSION

5.1 Mean Traits of the Classifications Linked to the First Four Main Components at Río Pama

According to the findings of the analysis, and particularly from the density chart showing the distribution of the individuals, the plotted points on the 1–2 and 3–4 axis or correlation circle, three groups (types) were selected in this sector, for which some of the mean traits are included, considering for this purpose the degree of importance of the variables in the components 1, 2, 3, and 4 (1).

Group 3

1. Trees which BHD could not be measured
2. Low height of ramification (x = 0.65 m)
3. Having the highest number of pods per kg in the sector (x = 456 pods/kg)
4. Have several shoots
5. Pods with medium thickness (x = 4.24 mm)
6. Pod length below average (12.9 cm)
7. Trees of average height (x = 17.2 m)
8. Having large amount of thorns (x = 27 thorns/meter section)
9. Number of seeds per kg above average (x = 39,120 seeds/kg)
10. Crown diameter under population average (x = 12.5 m)
11. Pod width at the middle below average (x = 9.24 mm)

Group 5

1. Group with few trees which BHD could be measured (x = 12.73 cm)
2. On average, they have low height of ramification (x = 0.1 m)
3. Having low amount of pods/kg (x = 184 pods/kg)
4. Trees with an average of 2 shoots
5. Very thick pods (5, 12 mm)
6. Pod length near average (x = 14.25 cm)
7. Trees of low height (x = 11.9 m)
8. Trees having large number of thorns (x = 28 thorns/meter section)
9. Low amount of seeds per kg (x = 20,980 seeds/kg)
10. Crown diameter below population average (x = 12.53 m)
11. Wide pods (x = 13.93 mm)

Group 9

1. Trees which BHD could be measured
2. Height of ramification above average (x = 2.92 m)
3. Low number of pods per kg (x = 177 pods/kg)
4. Having a single stem (x = 1)
5. Very thick pods (x = 5.32 mm)
6. Pods rather long (x = 18.46 cm)
7. Very tall trees (x = 23 m)
8. Having a low number of thorns (x = 9 thorns/meter section)
9. Seeds/kg below average (x = 28.696 seeds/kg)
10. Trees with large crown diameter (x = 17.5 m)
11. Having wide pods (x = 12.64 mm)

5.2 Mean Traits of the Classifications Linked to the First Four Main Components at Monte Patria

Basing on the findings of the correlations and projection charts for individuals and variables, four groups were selected in this sector, for which the mean traits of those variables falling closer together are indicated.

Group 3

1. Trees which diameter could not be measured
2. Branches growing from ground level (x = 0.0)
3. Small crown diameter (x = 8.38 m)
4. Low number of seeds per kg (x = 24,307 seeds/kg)
5. High number of seeds per pod (x = 20.2 seeds/pod)
6. Great pod thickness (x = 5.2 mm)
7. Trees with wide pods (x = 13.58 mm)
8. Individuals with low amount of pods per kg (x = 176 pods/kg)
9. Low number of damaged seeds (x = 2,115 damaged seeds/kg)
10. Pods longer than the populational average (x = 15.67 cm)
11. Thorns similar in length to the populational average (x = 2.03 cm)

Group 4

1. Trees which diameter could not be measured
2. Ramified from ground level (x = 0.0)
3. Small crown diameter (x = 6.12 m)
4. Thorn length above average (x = 2.57 cm)
5. High number of thorns (x = 34 thorns per meter section)
6. Average number of shoots from the base equaling 3
7. Trees of low height (x = 6.18 m)
8. Number of brachyblasts approaching the average (x = 23 brachyblasts/meter section)
9. Low amount of pods/kg (x = 291 pods/kg)
10. Number of seeds per kg below average (x = 34,783 seeds/kg)
11. Number of seeds per pod around average (x = 11.2 seeds/pod)

Group 5

1. Trees which diameter could be measured (x = 51.96 cm)
2. Height of ramification above population's average (x = 1.72 m)
3. Crown diameter above average (x = 12.95 m)
4. Trees with small thorns (x = 0.70 cm)
5. Having low number of thorns (x = 7 thorns/meter section)
6. Single stem (x = 1)
7. Tall trees compared to the average (x = 10.5 m)
8. High number of brachyblasts (x = 26.5 brachyblasts/meter section)
9. Low number of pods/kg (x = 288 pods/kg)
10. Number of seeds below average (x = 31,999 seeds/kg)
11. High number of seeds per pod (x = 16 seeds/pod)

Group 6

1. Large amount of trees which BHD could not be measured (x = 33.79 cm)
2. Ramification height above average (x = 1.8 m)
3. High number of seeds/kg (x = 87,000 seeds/kg)
4. Low number of seeds/pod (x = 3 seeds/pod)
5. Low pod thickness (x = 3.06 mm)
6. Narrow pods (x = 9.25 mm)
7. High number of pods/kg (x = 684 pods/kg)
8. High number of damaged seeds (x = 60,677 damaged seeds/kg)
9. Pods shorter in length than population's average (x = 10.45 cm)
10. Long thorns (x = 2.98 cm)
11. Small crown diameter (x = 8.5 m)

5.3 Mean Traits of the Classifications Linked to the First Four Main Components at Corral Quemado.

The mean traits are indicated for the groups listed below according to the most relevant variables that could be observed at the projection and classification charts, showing a high correlation with the four main components (1).

Group 1

1. Trees with high number of pods (x = 550 pods/kg)
2. Small pods (x = 10.47 cm)
3. Pods narrower than average (x = 9.07 cm)
4. Leaf length around population's average (x = 11.39 cm)
5. Leaf dry weight close to average (x = 2.78 gr)
6. Leaf width close to average (x = 4.41 cm)
7. Low number of seeds/pod (x = 11.0 seeds/pod)
8. BHD could not be measured
9. Pods narrower than average (x = 3.76 mm)
10. Large number of folioles (x = 36.0)
11. Tree height close to average (x = 7.53 m)

Group 4

1. Trees with low number of pods per kg (x = 214.6 pods/kg)
2. Pods longer than average (x = 14.97 cm)
3. Pod width similar to average (x = 11.65 mm)
4. Medium length leaves (x = 11.99 cm)
5. Leaf dry weight above average (x = 3.4 gr)
6. Wide leaves (x = 5.33 cm)
7. High number of seeds/pod (x = 21.4 seeds/pod)
8. BHD could be measured (x = 70.96 cm)
9. Pod thickness slightly above average (x = 4.93 mm)
10. Number of folioles below average (x = 27.6 folioles)
11. Tree height above average

Group 5

1. Number of pods per kg above average (x = 406.8 pods/kg)
2. Pod length close to average (x = 11.2 cm)
3. Pod width close to average (x = 9.52 mm)
4. Large-sized leaves (x = 13.37 cm)
5. Leaf dry weight above average (x = 3.4 gr)
6. Leaf width similar to average (x = 4.93 cm)
7. Low number of seeds/pod (x = 13.4 seeds/pod)
8. BHD could not be measured
9. Pod thickness below average (x = 4.21 mm)
10. Leaf with a high number of folioles (x = 36.0 folioles)
11. Low total height (x = 6.28 m)

Group 9

1. Low number of pods/kg (x = 347 pods/kg)
2. Pod length close to average (x = 12.4 cm)
3. Narrow pod (x = 8.57 mm)
4. Short leaves (x = 5.89 cm)
5. Low leaf dry weight (x = 0.46 gr)
6. Narrow leaves (x = 1.79 cm)
7. Low number of seeds per pod (x = 11 seeds/pod)
8. BHD could not be measured
9. Great pod thickness (x = 6.64 mm)
10. Low number of folioles (x = 23 folioles)
11. Tree height close to population's average (x = 7.85 m)

5.4 Mean Traits of the Classifications Linked to the First Four Main Components at Quebrada Marquesa.

Four groups were selected basing on the projections of the individuals and the variables, added to the distribution into ten classes, the main traits of which are described according to the variables which showed the best correlation with the main components.

Group 1

1. Short-sized trees (x = 4.4 m)
2. Number of seeds/kg below average (x = 34,356 seeds/kg)
3. Small crown diameter (x = 5.97 m)
4. Small number of damaged seeds (x = 4,406 damaged seeds/kg)
5. Large number of seeds/pod (x = 17.62 seeds/pod)
6. Large thorns (x = 2.24 cm)
7. BHD could not be measured
8. Large number of thorns (x = 28.87 thorns/meter section)
9. Low number of leaves/brachyblast (x = 2.8 leaves/brachyblast)
10. Narrow leaves (x = 4.31 cm)
11. Low number of pods/kg (x = 333 pods/kg)

Group 4

1. Short-sized trees (x = 5.67 m)
2. Considerable number of seeds/kg (x = 43,459 seeds/kg)
3. High number of pods/kg (x = 1,040 pods/kg)
4. Narrow leaves (x = 2.38 cm)
5. Low number of seeds/pod (x = 5 seeds/pod)
6. Narrow pods (x = 8.47 mm)
7. Short pods (x = 7.19 cm)
8. Flat or low-thickness pods (x = 3.56 mm)
9. High number of thorns (x = 29 thorns/meter section)
10. Short leaves (x = 6.77 cm)
11. Small crown diameter (x = 6.23 m)

Group 5

1. Short-sized trees (x = 5.5 m)
2. Low number of seeds/kg (x = 31,402 seeds/kg)
3. Low number of pods/kg (x = 235 pods/kg)
4. Broad leaves (x = 5.13 cm)
5. High number of seeds per pod (x = 17.5 seeds/pod)
6. Broad pods (x = 12.76 mm)
7. Long pods (x = 12.98 cm)
8. Very thick pods (x = 4.35 mm)
9. Number of thorns below average (x = 20 thorns/meter section)
10. Leaf length close to average (x = 10.2 cm)
11. Small crown diameter (x = 6.51 m)

Group 8

1. Tall trees compared to average (x = 8.7 m)
2. High number of seeds/kg (x = 40,590 seeds/kg)
3. Considerable crown diameter (x = 14.3 m)
4. Leaf length close to average (x = 10.57 cm)
5. Number of seeds per pod around average (x = 13.66 seeds/pod)
6. Short thorns (x = 0.7 cm)
7. BHD could not be measured
8. Low number of thorns (x = 1 thorn/meter section)
9. Number of leaves/brachyblast near average (x = 3.3 leaves/brachyblast)
10. Broad leaves (x = 5.63 cm)
11. Low number of pods/kg (x = 263 pods/kg)

5.5 Mean Traits of the Classifications Linked to the Four Main Components in all of the Populations Surveyed.

Three “plus groups” were selected basing on the projection of the variables on the correlation circle, the distribution of the individuals into ten classes and the order of importance of the variables in each component (1). Some of their mean traits are defined below.

Group 1

1. Trees with a high number of pods/kg (x = 724 pods/kg)
2. Low number of seeds/pod (x = 5.17 seeds/pod)
3. High number of seeds/kg (x = 66,260 seeds/kg)
4. Thin pods (x = 3.15 mm)
5. High number of damaged seeds (x = 43,127 damaged seeds/kg)
6. Trees ramified from a low height (x = 0.4 m)
7. Leaf length near average or rather short compared to the other two Groups (x = 10.54 cm)
8. Small BHD (x = 10.54 cm)
9. Low pod dry weight (x = 81.23%)
10. Leaf width near average (x = 4.4 cm)

Group 3

1. Trees with a low number of pods/kg (x = 280 pods/kg)
2. High number of seeds/pod (x = 31 seeds/pod)
3. Very thick pods (x = 4.9 mm)
4. Low number of seeds/kg (x = 31,120 seeds/kg)
5. Trees with low number of damaged seeds (x = 7,240 damaged seeds/kg)
6. Trees branching out from a low height (x = 1.76 m)
7. Leaves slightly longer than average (x = 11.16 cm)
8. BHD greater than average (x = 47.5 cm)
9. Low dry pod weight (x = 83.71%)
10. Leaves slightly narrower than average (x = 4.37 cm)

Group 9

1. Trees with number of pods/kg near average (x = 338 pods/kg)
2. Number of seeds/pod near average (x = 14 seeds/pod)
3. Trees with low number of seeds/kg (x = 34,490 seeds/kg)
4. Very thick pods (x = 5.06 mm)
5. Low number of damaged seeds (x = 5,187 damaged seeds/kg)
6. Branching out from ground level (x = 0.00 m)
7. Short leaves (x = 8.65 cm)
8. BHD could not be measured
9. High dry pod weight (x = 86.8%)
10. Narrow leaves (x = 3.17 cm)

6. CONCLUSIONS

1. The variables considered in this survey generally showed good correlation among themselves and grouped sampling units around sets determined by the variations of these traits, with the exception of the variable “branch diameter” (V₁₃) which achieved no degree of importance in the different analyses.

2. From the morphologic traits group, the traits which achieved more relevance where those related to the pods for the five analyses made.

3. The analysis shows considerable diversity in the traits, being possible to define different individuals morphologically at each population. This also happens in the overall analysis. The following morphotypes are distinguished:

4. It would be convenient to work on the reproduction of the morphotypes identified, with the purpose of establishing —under similar soil and climatic conditions— if the morphological differences are of an environmental or genotypical nature.

5. As regards the analysis used, it may be concluded that it is efficient in multivariable comparations. It must be stressed that a careful selection of the variables to be used is essential.

REFERENCES

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APPENDIX

MAP SHOWING LOCATION OF SECTORS SURVEYED

(II PART)

EVALUATION OF PROSOPIS CHILENSIS PLANTATIONS AT REGION IV

1. GENERAL BACKGROUND

The National Forestry Corporation-Region IV has established a number of plantations with Prosopis chilensis, among which stand out those carried out in 1981 at various locations. These plantations are aimed at determining variations permitting an optimum management of the species. At this stage, some sectors were planted with schemes which considered different spacings.

The project has been labelled Management and Adaptation of Prosopis chilensis, with the participation of the Forestry School of the University of Chile.

In 1976 a small plantation —approximately 300 plants on 2 hectares— was established as part of the treatments on the slopes draining into the La Paloma Reservoir.

2. MATERIAL AND METHOD

2.1 Sectors surveyed

The main sectors with plantations of Prosopis chilensis in Region IV are shown below, including the planting years:

2.2 Surveyed Locations

Only the more representative places were considered in the growth evaluation of this species:

• La Muñosana
• Monte Patria
• Higueritas

The variables evaluated were: total height and collar diameter.

3. RESULTS

Logomorph presence and damage was detected at all sites, greatly affecting the plants. The effects are mainly reduced height gains, as this animal usually cuts off the main shoot.

4. CONCLUSIONS

1. Direct evaluation, without the application of a correcting factor to account for logomorph damage, may lead to wrong assessment of the growth rates.

2. Considerable annual growth was observed at the Muñosana sector.

3. Prosopis chilensis adapts well, but in the early growth stages it is greatly affected by animal attack.