EXPLORATION, COLLECTION AND EVALUATION OF CORDIA ALLIODORA (R. & P.) OKEN

by

J.W. Stead
Research Officer
Unit of Tropical Silviculture
Commonwealth Forestry Institute
Oxford, U.K.

INTRODUCTION

In 1963 the Commonwealth Forestry Institute began a programme to study some important forest tree species in Central America, e.g. Pinus caribaea Mor. and Cedrela odorata L.. More recently selection of species for inclusion in this programme has followed the guidelines given by the “FAO Panel of Experts on Forest Gene Resources” in their “Forest genetic resources priorities (by region, species and operation)” (see e.g. FAO 1977 pp.50–71). The sequence of study has been the exploration of a species' range and variation and collection of seeds at carefully selected sites, followed by distribution of the seeds for replicated trials in countries throughout the tropics. Details of the work have appeared in this series. (Kemp, 1973; Anon, 1976). Interest so far has centred on the pines (Pinus caribaea, P. oocarpa Schiede and P. pseudostrobus Lindl. (incl. P. tenuifolia Benth.)) but in 1976 a three year project began to study Cordia alliodora (R. & P.) Oken.

CORDIA ALLIODORA

Some details about the species are presented here. Much of this was obtained from a review article by Johnson and Morales (1972) which brings together a lot of the available information.

Vernacular names: These are numerous from throughout the species' range. “Laurel” is widely used in Central America and Ecuador.

Family: Boraginaceae.

Latin name: Cordia alliodora (R. & P.) Oken, Allg. Naturgeschichte, Bot. 2²: 1098 (1841).

Botanical description: Medium to large tree. Leaves alternate, simple, entire, oblong to lanceolate to elliptic, usually broadest at or above the middle, 10 – 20 cm long, 3 – 8 cm broad, with the base acute or obtuse and the apex acuminate. Upper surface stellate-pubescent or glabrate, lower surface paler, stellate-tomentose or glabrescent with 5 – 7 pairs of lateral veins. Petiole 1 – 3 cm long. The amount, character, and colour of the pubescence on the leaves is very variable.

The leafy twigs towards their apex and frequently even the axis of the inflorescence, develop irregular swellings that serve as ant domatia. The extent of this habit varies throughout the range, being most prominent in Central America and north-western South America and almost absent in the West Indies and southern South America.

Perfect flowers crowded on a loosely and widely branched terminal panicle 10 – 30 cm across. Calyx cylindrical with ten prominent ribs, densely tomentose, 4 – 6 mm long, 2 – 2.5 mm thick with 5 inconspicuous lobes. Corolla white, drying brown, persistent lobes oblong, 5 – 7 mm long, 1.5 – 3.5 mm broad and spreading. Stamens 5, erect, white protruding well beyond the exserted style. Style 2-forked, each fork with 2 broad stigmas. Fruit cylindrical with fibrous, chartaceous wall, 3 – 5 mm long, completely enveloped by the tube of the corolla and the ensheathing calyx-tube. Lobes of persistent corolla function as a parachute in fruit dispersal.

GEOGRAPHICAL RANGE AND HABITAT

C. alliodora is the most widespread species of the genus and is found in Latin America from Misiones, Argentina (lat. 25°S) to Sinaloa, Mexico (lat. 25°N). Over this wide range considerable variation can be seen in some botanical characters (e.g. pubescence and flower size), and Johnson and Morales (1972) and Whitmore ¹ (pers. comm.) have suggested that two or more taxa may be involved. It occurs in most of the mainland countries between these two extremes but Vega (1977) considers it an exotic in Surinam. It has been reported from most of the Caribbean islands from eastern Cuba to Trinidad but is probably not native to Jamaica. It seems to be particularly common in Central America and north-western South America.

The best specimens of C. alliodora have been found in areas with moderate to high rainfall (2000 – 5000 mm rainfall, +24°C). In Central America it is also common in drier areas (1000 – 2000 mm rainfall) but here, growth is slower and the form of the trees is not so impressive. Similarly, it is wide ranging in its altitudinal preference and voucher specimens and/or seed for this project have been collected from areas just above sea level (e.g. Caribbean coast of Honduras and Costa Rica; Pacific coast of Ecuador) to 2000 m a.s.l. (Colombia). (For further examples see Table 4). A wide variety of site-soil conditions have been reported acceptable for growth of C. alliodora. Occurrence of natural stands in the Costa Rican lowlands is more dependent on the management policies of individual farmers than on actual site conditions, but stands are more vigorous when growing on well-drained medium-textured soils.

¹ J.L. Whitmore, Institute of Tropical Forestry, University of Puerto Rico, Agricultural Experiment Station, P.O. Box AQ, Rio Piedras, Puerto Rico 00928, USA.

POTENTIAL VALUE

C. alliodora is a well known timber tree throughout its natural range. This reputation has justified small scale testing of growth potential and wood properties and the results available so far indicate that comprehensive testing would be desirable.

In its natural environment C. alliodora is a good coloniser which regenerates easily and occurs in almost pure stands in natural breaks in the forest or areas cleared by man. Mature trees can be found over 30 m tall and 1 m in diameter with an erect, cylindrical bole and a small compact crown. It is considered to be wind firm and has no known serious pests. (See Photo 1).

Data on growth rate are only available from small trial plots and some individual trees. Johnson and Morales (1972) give some of the information available from Costa Rica; and the following table, extracted from that review, gives an idea of the potential of the species:

Table 1. Growth data for Cordia alliodora from plantations in Costa Rica

* Approx. site conditions: altitude         50 m a.s.l.;   rainfall     5000 mm/an.
**     "          "          "               "            650 m a.s.l.;      "            2700 mm/an.

Vega (1977), projecting from early results of experiments with C. alliodora in Surinam, considers that similarly good results could be obtained from plantations in that country. Peck (1976) found that trial plantations in the area of Tumaco, Colombia, with an average height of 12m and average diameter of 12cm at 3 years of age, had performed outstandingly compared with 16 other native species and 10 exotic species included in the same project. There are now quite extensive plantations of C. alliodora around Tumaco and experiments have been performed on establishment using the Taungya system. Photo 2 shows some of the trees from these experiments. Results from trials in Africa are similarly promising.

Some data for the physical and mechanical properties of the wood of C. alliodora are given in Table 2. Full details of the wood anatomy are given in Johnson and Morales (1972). The wood seasons easily but has been reported to be variously resistant and susceptible to decay and easy or difficult to treat with different techniques. The appearance is good and it is easy to work. The principal uses are construction of various kinds, furniture, veneer and plywood. It remains to be seen whether the species will be suitable for pulping.

Table 2. Some wood properties of C. alliodora

STATUS

Summarising the above information it can be seen that C. alliodora is quite common throughout its range in Latin America where it is highly valued as a timber tree. Tests on the timber and growth rate suggest that full scale testing would be justified. Similarly, further study of the botany is required. This situation is reflected in the FAO Panel of Experts' (see FAO 1977) assessment of the species. They do not consider C. alliodora to be in urgent need of conservation but, because it is an important timber species, they give maximum priority to work on botanical/genecological exploration and evaluation (collecting of seed for provenance trials).

On the basis of these recommendations C. alliodora was included in the CFI programme.

THE CFI PROJECT

Exploration: From the botanical literature, herbarium material and the experience of workers in the field it was estimated that C. alliodora flowers about February/March in Central America, and seed fall was estimated to be about April/May. Therefore, in early 1977, an extensive journey of exploration was made throughout Nicaragua, Honduras, Guatemala and Belize.

Trees of C. alliodora in full white flower are conspicuous and so it was quite easy to estimate range and frequency whilst travelling; but only from herbarium samples collected at regular intervals, was it possible to check that this was indeed C. alliodora and not, for example, the closely related C. gerascanthus L.

Throughout the exploration, areas were tentatively selected as seed collecting sites. Suitable sites had a large number of flowering trees in a well defined area of about one km². Terrain and undergrowth had to be such as to permit collecting, and in every case the permission of the land owner was obtained. From these initial observations it was possible to select a group of sites which, as well as possible, covered the range of altitudinal and habitat preference that had been found. Particular attention was paid to provenances from the “wet” Atlantic coast and the “dry” Pacific coast.

Collection: In the same season plans were made to collect seed from these sites. C. alliodora produces fruit in abundance but it has proved difficult to collect and store seed satisfactorily. However, Tschinkel (1967) and Vega (1977) both conclude that there is a limited period of 2–3 weeks before seed fall when good seed can be collected, which, if stored at low temperature and humidity, will survive long enough to be of use in establishment of trials or plantations.

The plan was to collect roughly equal amounts of seed from at least 25 trees per site. From small collections in previous years it was calculated that there are approximately 60–70 000 seeds per kg. With this figure, and an estimate of the percentage germination, it was possible to calculate the weight of seed required for trials. Within sites in Central America the phenology of fruiting was found to be quite well synchronised, and it was quite easy to find 25 trees at about the same stage of development. This was not the case throughout the range of the species, e.g. in Colombia, where trees can be found in flower at any season of the year, which can make collecting from a large number of trees very difficult.

Though seed collection of C. alliodora is reported to be difficult, with careful observation of development it was possible to achieve our collecting aims. In the later stages of development the fruit swells and protrudes out of the enclosing calyx and in drying, turns from green to brown. Mature seed falls naturally from the trees and the collecting technique employed, which is strongly recommended, was simply to shake the selected trees and gather the falling seed in extended sheets. That the seed, collected by this method, stores and germinates¹ well can be seen in the results of tests given in Table 3.

The apparent improvement in viability is partly explained by a change in the test recording system which now includes abnormal seedlings. Low moisture content (<10%) has been found to be important for good storage. Lot 33/77 had a moisture content of 11.45% in 1977 and germination of 63%, which fell to 31% in 1978.

Table 3. Germination results, at collecting and after 1 year in store, for seed of Cordia alliodora collected by the CFI in Central America

In the first year seed was collected from six sites and two further collections were added in 1978. Meanwhile, cooperating organisations were helping with collections in other parts of the extensive range of the species. A list of collection sites is given in Appendix 1.

Evaluation: Interest in trials has been ascertained from a questionnaire sent round to various organisations in about 30 countries. Those that confirmed their interest were sent sets of provenance collections in 1977; some requested seed from the more extensive collections made in 1978. Further enquiries about seed are still being received. So far, seed for 89 trials have been sent to 22 countries (listed in Appendix 2). Seed from quite a wide range of provenances is still available for interested countries though the longevity is rather uncertain. It may be possible, from early results of trials, to predict which will be the better provenances and make further collections at these sites.

Countries participating in the programme organise the trials according to their own requirements and preferences. At the same time a Randomised Complete Block (RCB) design of 49-tree plots, planted at 3 × 3 m spacing, and replicated five times per provenance has been recommended, in order to get a degree of standardisation. Countries are encouraged to analyse and publish their results wherever possible but it is hoped that the data can be gathered together to facilitate international comparison and thus derive greater benefit from the trials.

¹ Seed collected by the CFI is stored and tested by the Seed Laboratory of the Forestry Commission at Alice Holt Lodge, Farnham, Surrey, U.K.

BIBLIOGRAPHY

Anon 1976 International Provenance Trials of P. pseudostrobus. FAO, Rome. Forestry Occasional Paper 1976/1 pp.19–21.

FAO 1977 Report of the Fourth Session of the FAO Panel of Experts on Forest Gene Resources. FAO, Rome. FO:FGR/4/Rep. 75 pp.

Johnson P. and Morales, R. 1972 A review of Cordia alliodora (Ruiz and Pav.) Oken. Turrialba 22 (2) : 210 – 220.

Kemp, R.H. 1973 Central American Pine Research Project. FAO, Rome. Forestry Occasional Paper 1973/1 pp.5 – 15.

Peck, R.B. 1976 Selección preliminar de especies aptas para el establecimiento de bosques artificiales en tierra firme del litoral pacífico de Colombia. Instituto Forestal Latino-Americano (IFLAIC), Mérida, Venezuela. Boletín No.50 pp. 29 – 39.

Tschinkel, H. 1967 La madurez y el almacenamiento de semillas de Cordia alliodora (Ruiz and Pav.) Cham. Turrialba 17(1) : 89 – 90.

Vega, L. 1977 La silvicultura de Cordia alliodora (R. and P.) Oken como especie exótica en Surinam. Instituto Forestal Latino-Americano (IFLAIC), Mérida, Venezuela. Boletín No. 52 pp.3 – 26.

Appendix 1.

Cordia alliodora seed collection sites

Appendix 2.

Countries participating in trials of Cordia alliodora

(The figure in brackets indicates the number of trials allocated). Belize (3), Brazil (1), Colombia (5), Congo Rep. (1), Costa Rica (2), Ecuador (3), Fiji (4), Ghana (6), Honduras (1), India (10), Ivory Coast (2), Liberia (2), Mexico (13), New Hebrides (1), Nigeria (11), Sri Lanka (6), Sierra Leone (4), Solomon Islands (4), Sudan (4), Surinam (1), Trinidad (4), Venezuela (1).

	Photo 1. Natural regeneration of Cordia alliodora in Limón Province, Costa Rica.
Photo 2. Cordia alliodora established using the Taungya system near Tumaco, Colombia, at 6 years old.