U AUNG DIN, Forestry Division, FAO
Distribution of tropical pines
Some with introduced pines in the tropics
Practices adopted with introduced pines
Conclusions
References
In the tropics there is a dearth of softwoods relative to hardwoods. The properties and the versatile uses of conifers are, however, fully appreciated and increasing attention is being paid in all tropical countries to the growing of pines in planning national forestry programs. This paper summarizes information useful in the choice of species for introduction and planting. 1
1 This paper supplements the section on tropical conifers contained in the FAO publication Tropical Silviculture, Volume I.
Pine forests occurring in the tropics are often held to be mere extensions of temperate zone forests into the tropical zone, and it is maintained that the only true tropical pines in the whole world are P. merkusii in the Asia region, and P. hondurensis in Mexico to Nicaragua and in the West Indies. There are none at all in Africa. Although species like P. longifolia in India, P. khasya in Burma and neighboring countries, P. insularis in the Philippines, P. strobus (var. chiapensis) in Central America, P. occidentalis, P. tropicalis, and P. cubensis of the West Indies may also be regarded as tropical, they extend their range into subtropical elevational belts of 3,000 to 6,000 feet (1,000 to 2,000 meters) or beyond.
In this paper the term "tropical pines" is taken to include all pines as they occur naturally in the tropical region, that is, including those to be found at high elevational belts where subtropical or temperate climatic conditions prevail.
Strictly, those areas lying within the tropics of Cancer and Capricorn (23 ½ N and S) constitute the tropical region of the world, but in order to include the 'outer tropics', as well as the transitional zone merging imperceptibly into the subtropics, 30° N and S latitudes will be taken here as the limits of the region. This corresponds approximately to the area bounded by a zone with a mean annual temperature range of 70°-75° F (21.1°-24° C) (See Figure 1).
This somewhat arbitrary delineation has the advantage of including nearly the whole of Mexico, which is perhaps the richest pine-growing region in the world in terms of number of species. It also includes a major portion of South Africa where experiences with numerous exotic pines read like a success story.
In natural distribution, it appears that the genus Pinus has been unable to cross the equator and the belt of tropical and equatorial forests astride it. This seems to have offered, as it were, a sufficient obstacle to the spread of pines into the southern hemisphere with the exception of a single species, namely P. merkusii. P. merkusii; occurs in India, Burma, Thailand, Cambodia, Viet-Nam, the Philippine islands in the northern hemisphere and, below the equator, in Sumatra, Java, Borneo in the Indonesian islands. But in neither Australia nor New Zealand is the genus Pinus represented.
There are no indigenous pines in the whole continent of Africa, whether tropical or otherwise. However, there is one species P. canariensis in the Canary islands off the northwest coast of Africa.
Likewise, no indigenous species of pine occurs in South America, the southern limit of pines in Central America being in Nicaragua - still some 12° north of the equator.
Before proceeding to allocate species in the different countries of the region to a definite type of climate as characterized by temperature, altitude, and rainfall, some general remarks are desirable.
Thermal zones and temperature
On the basis of latitude, with average temperatures falling as one proceeds north or south of the equator, the usual rough differentiation of climatic zones is into tropical, subtropical, temperate and arctic. But owing to the uneven distribution of land and water as well as to other local factors, great variations occur within the zones as defined by latitude. It may roughly be taken that for each 1° rising latitude, there is a fall of 1° F in the mean annual temperature, while the mean annual temperature of 75° F (24° C) is generally accepted as characterizing tropical climates. Variation in temperature in the course of the year tends to increase with increasing latitude, implying a greater difference between the longest and shortest day, and also with decreasing rainfall values, while on the other hand it becomes less at high altitudes or with close proximity to the sea.
The following general differentiation of climates based on mean annual temperatures may be given:
|
Region |
Mean temperature |
|
|
F |
C |
|
|
Tropical |
over 75° |
over 24° |
|
Subtropical |
67° to 75° |
19.5° to 24° |
|
Warm temperate |
62° to 67° |
18.6° to 19.5° |
|
Cold temperate |
50° to 62° |
10° to 16.6° |
|
Arctic |
less than 50° |
less than 10° |
Rainfall
There are two distinctive features in the general world distribution of rainfall:
(1) the existence of two dry zones roughly along the 30° latitude north and south of the equator, which in fact is the limit of the area of the present study;(2) general increase of precipitation outwards from these zones towards the equator and the poles.
But variations in rainfall are caused by such factors as local topography, proximity to the sea, and the influence of monsoons or trade winds, etc.
Distribution of rainfall is no less important than the total amount, and in the world three main types of rainfall may be distinguished:
(a) pronounced summer rainfall;
(b) well-distributed rainfall;
(c) pronounced winter rainfall.
Each gives rise to a distinct type of vegetation.
Within the 30° N and 30° S limits, however, there are two distinct patterns of rainfall distribution which are important in this connection:
(i) seasonal rainfall - i.e., with a distinct rainy season;(ii) rainfall evenly distributed throughout the year - sometimes with one or two slightly pronounced peak seasons.
In contrast to the other thermal belts as differentiated by increase in latitude, in the tropics it is not so important whether the rainfall occurs in the summer or winter, there being no pronounced season of winter. Most rains fall in the hottest months during summer when the sun is highest, while the so-called winter is relatively a dry season.
In conformity with the broad classification employed in the FAO publication Tropical Silviculture, it will also be convenient here to distinguish three rainfall intensity classes, namely:
1. areas with over 76 inches (1,900 millimeters), as in wet forests;2. areas with 40-75 inches (1,000-1,900 milk meters), as in moist forests;
3. areas with less than 40 inches (1,000 millimeters) as in dry forests inclusive of thorn forests and semiarid areas.
It must, of course, be noted that these rainfall figures for delineation will vary from one region to another, and they tend to decrease with increase in latitude, that is, distance away from the equator. In other words, in more northerly or southerly latitudes a particular type of vegetation can do with less rainfall than in localities nearer to the equator.
Altitude and temperature
The rate of decrease in average temperature with elevation is approximately taken as 1° F for every 300 feet (90 meters) of altitude everywhere in the world. But within the tropics the difference in elevation necessary for a 1°F drop of mean temperature is nearer 400 feet (120 meters) than 300 feet (90 meters) up to about 3,000 feet (900 meters), above which the fall is more rapid and approximates to the general world figure. Apart from variations due to local factors, the rate of fall also varies at different times of the year, being smaller in winter than in summer.
At higher elevations, the occurrence of frost is important, while at sufficiently high altitudes precipitation takes the form of snow which may accumulate and lie on the ground for varying periods. Both frost and snow have important influence on the vegetation. Ground frost may cause the die-back of low vegetation and seedlings. A layer of snow on the ground acts as a protective cover to the soil and ground vegetation by preventing further drops in temperature, while its gradual melting in spring is also a valuable source of moisture for the vegetation. In this respect 1 foot (304 millimeters) of snowfall is generally taken as the equivalent of 1 inch (25 millimeters) of rainfall. In areas bordering the external limits of the region being considered in this paper, frost occurs regularly in winter at heights above about 3,000 feet (900 meters), while as one proceeds towards the more equable areas near the equator frost rarely occurs below 6,000 feet (1,800 meters). Likewise, though snow may occasionally fall at elevations down to 4,000 feet (1,200 meters) near the 30° parallel limits, it does not lie for any appreciable period below about 7,000 feet (2,100 meters). Nearer the equator, snow seldom falls below 10,000 feet (3,000 meters); there is perpetual snow on the ground beyond 16,000 feet (4,800 meters).
Table 1 shows an empirical division of the elevational belts, based on mean temperature ranges so as to correspond in a rough manner to the world's thermal belts as differentiated by latitudes, and for the purpose of allocating species to a definite elevational belt. In this respect, as consideration of this altitude-temperature relationship is restricted to the region within the 30° N and S limits, the problem is somewhat more simple than if the other variable of latitude is introduced. This does not, of course, mean that the effect of change in latitude is not present, but the influence becomes only appreciably pronounced towards the limiting parallels of 30° N and S.
TABLE 1. - EMPIRICAL DIVISION INTO ELEVATION BELTS BASED ON TEMPERATURE RANGES
|
Climatic conditions |
Mean temperature |
Altitude |
Remarks |
|
Tropical |
Over 75°F (24°C) |
Up to 3,000 feet (900 meters) |
|
|
Subtropical |
67°-75°F (19.5-24°C) |
3,000-0,000 feet (900-1,800 frosts in meters) |
(Occasional frost in winter) |
|
Warm temperate |
62°-67°F (16.6-19.5°C) |
6,000-9,000 feet (1,800-2,700 meters) |
(Light frosts in winter) |
|
Cold temperate |
50°-62°F (10°-16.6° C) |
9,000-13,000 feet (2,700-4,000 meters) |
(Severe frosts in winter) |
|
Arctic |
Less than 50°F |
Over 13,000 feet (4,000 meters) |
|
At this juncture a few words of caution should be given. In the first place, in delineating rainfall zones or thermal belts corresponding to attitudinal ranges, it is never possible to draw a sharp line of demarcation between one belt and the other or between classes. Likewise in allocating a species to a thermal belt, altitudinal range, or rainfall intensity class, it must always be borne in mind that within the given range of conditions under which a species occurs there is bound to exist an optimum, and further that it is always possible for a species to encroach on colder or warmer thermal zones, into lower and higher elevational belts, or into areas of lower or higher rainfall intensity classes.
Secondly, in respect of temperature, elevation and rainfall, these represent very broad classifications, and it is always not only possible but also desirable to subdivide further those given under each of the three factors according to local requirements.
Thirdly, exact correspondence between the climates of thermal belts differentiated on the bases of latitude and altitude is by no means to be assumed. To take one example - Kikuyu, at 6,800 feet (2,073 meters) above the sea in Kenya, and Lisbon have about the same mean annual temperature of 61°F and 60°F (16.1. 15.6°C) respectively, but the difference between the mean temperatures of the coolest and warmest months is only 8°F at the former compared with 22°F at the latter. In other words, there is greater uniformity throughout the year in the tropics and this factor, together with the absence of any definite resting period such as pines experience in more northerly homes, can often be the cause of failure of some species introduced in equatorial highlands. Further, in recognition of this lack of exactitude between the climates, those based on elevational belts are often described as tropical, subtropical, lower montane, higher montane, subalpine, alpine, etc.
Asia
There are only six species of pines in the Indo-Malaysian region, of which three, P. excelsa P. longifolia, and P. gerardiana are Himalayan. P. khasya occurs in Assam and Burma, P. merkusii in Burma, Thailand, Cambodia, Indonesia and the Philippines, while P. insularis, which is closely akin to P. khasya, is to be found only in the Philippines (see Graph 1).
1. P. excelsa (wallichiana). Confined essentially to the temperate regions of the Himalayas (6,000-10,000 feet or 2,000-3,000 meters) and stretching from Afghanistan in the west to Bhutan in the east, P. excelsa may descend to 4,000 feet (1,200 meters) and ascend to 12,000 feet (3,650 meters); temperature range 0°F (- 17.8°C) to 100°F (37.8°C) and 40 to 60 inches (1,000 to 1,900 millimeters) of rain with snowfall in winter.2. P. longifolia. Found at 1,600 to 7,600 feet (460. 2,280 meters) from Afghanistan to Bhutan in India, towards the lower limit P. longifolia is often associated with such low-level species as Shorea robusta, Buchaniana latifolia, Anogeissus latifolia, Bacchinia sp.; temperature range 25°F to 110°F (-4°C to 43.3°C); rainfall 35 to 110 inches (890 to 2,800 millimeters).
3. P. gerardiana. This species is found at the same altitude as P. excelsa, but in drier localities outside the effects of monsoons with only slight snowfall and rain of 15 to 30 inches (380 to 760 millimeters) in Afghanistan, Pakistan and the Himalayas. It furnishes edible seeds.
4. P. khasya. The Khasi and Naga hills in Manipur extending to hills of upper Burma at 2,500 to 7,500 feet (760 to 2,280 meters) are the natural habitat of P. khasya; mixed with oaks, chestnuts and ether broadleaved trees; rainfall over 75 inches (1,100 millimeters) and temperatures 30° to 100°F (-1.11° to 37.8°C) with possible light frosts in winter.
5. P. insularis - Similar to P. khasya, P. insularis is, however, found only in the Philippines at 3,000 to 7,000 feet (900 to 2,100 meters) with rainfall as high as 140 inches (3,600 millimeters).
6. P. merkusii - the most tropical of all pines and the only species to cross the equator to the southern hemisphere, P. merkusii is found in Burma, Thailand, Cambodia, Indonesia, Philippines at 500 to 3,000 feet (150 to 900 meters) with heavy rainfall (over 75 inches or 1,900 millimeters) but on well-drained porous soil, and frequently on dry ground.
Growth pattern of six pine a species in tropical Asia and 38 pine species in tropical America. Numerous relating to these species are referred to in the relevant text and also in Table 2. The triangle represents a mountain: the space on the left represents an area with over 75 inches (1,900 mm.) rainfall; on the right, under 40 inches (1,000 mm.), and, within the triangle, an area with 40 to 76 inches (1,000 to 1,900 mm.) rainfall.
In China, within the 30° limit, there are four species as follows:
P. armandi, on mountains of China in Shensi, Yunnan, Szechwan;
P. bungeana, on limestone rocks in the central mountains of China;
P. massoniana, in southeast China following the valley of the Yangtse into Szechwan;
P. tabulaeformis, in West Yunnan and Szechwan.
Africa
P. canariensis is a native of the Canary Islands between 2,500 feet and 8,000 feet (750 to 2,400 meters), usually on dry slopes an volcanic soil. Essentially a tree of the subtropical climate with long periods of drought with a considerable winter rainfall, it furnishers one of the best timbers among pines, being both strong and durable.
America
In Mexico, ² there are over 30 species (see Table 2) with an equally large number of varieties mostly growing at elevations between 4,000 feet and 15,000 feet (1,200 to 4,500 meters) above sea level. Five of the species (P. hondurensis, P. oocarpa, P. montezumae, P. pseudostrobus, P. tenuifolia) follow the mountains into Central America and as far south as Nicaragua. There are four species (P. occidentalis, P. hondurensis, P. tropicalis, P. cubensis) in the Caribbean - one in the Bahamas (P. hondurensis), one in Haiti (P. occidentalis), all four in Cuba, and two on the Isle of Pines (P. tropicalis, P. hondurensis). Pines are absent from the native flora of Puerto Rico, Jamaica, Lesser Antilles, Costa Rica, Panama, and South America.
² Systematics of Central-American pines are still in need of research and clarification as well as agreement among botanists. In this paper former P. caribaea has been treated as being separated into P. elliottii of Georgia and Florida, and P. hondurensis of Honduras, Guatemala; the latter species is also used to denote P. caribaea of the West Indies islands. Likewise, P. tropicalis, P. cubensis, P. occidentalis, which some authors consider synonymous, are treated as separate here.
TABLE 2. - PINE SPECIES TO BE FOUND IN TROPICAL AMERICA
TABLE 2. - PINE SPECIES TO BE FOUND IN TROPICAL AMERICA (Continued)
The introduction of new species into an area is most likely to give successful and satisfactory results when carried out under either of the following two conditions:
Condition 1. from one country to another of the 'tropical region', i.e., within the 300 N and 30° S latitudes, in which case it is only necessary to grow the new species at nearly the same altitude or within the same elevational belt as in the home country;Condition 2. from outside the 'tropical region' areas, i.e. from countries of higher latitude into localities of the 'tropical region', in which case it will be necessary to seek out areas with sufficiently high elevation to produce comparable thermal equivalent in the climate;
further provided that the new home of the species belongs to the same rainfall intensity class (whether wet, moist, or dry) as the country of origin.
Mean annual temperature, though useful, is not in itself sufficient indication of the range, which should further be narrowed down by consideration of not only the mean temperatures of the hottest and coolest months, but also the absolute maximum and minimum temperatures to be endured in the new home.
Another factor which greatly influences the successful introduction ³ of species is the existence of races or strains and the consideration of provenance. To give an example - in Malaya, lowland planting of P. insularis with seed from the Philippines at over 6,000 feet (1,800 meters) altitude resulted in failure. But subsequent attempts with seed obtained from trees which had spread to lower elevations of 1,500 to 2,000 feet (450 to 600 meters) as a result of shifting cultivation, proved successful. Many similar examples may be quoted from other countries.
³ An exotic is considered fully established and naturalized in its new home when it produces fertile seeds or regenerates itself.
Experiences in various countries seem to indicate that introduction under condition 1 gives far better results than that under condition 2. This is understandable as, although one passes through a similar progression of thermal belts with increase of altitude to that encountered on proceeding from the equator toward the poles, there can never be the same degree of approximation in climates as obtained under condition 1, particularly in regard to such factors as pressure, insolation, radiation, pattern of rainfall distribution and temperature variation, differences of which are bound to influence the species in the new habitat. However, experience with 'nontropical' pines is included below.
TABLE 3. - THE SPECIES ALLOCATED TO THEIR RESPECTIVE THERMAL ZONES
|
Tropical over 75°F mean (24°C) |
Subtropical 67°F - 75°F (19.5°C - 24°C) |
Warm temperate 62°F - 67°C (16.6°C - 19.6°C) |
Cold temperate 50.F - 62°F (10°C - 16.6°C) |
Arctic below 50°C (10°C) |
|
1. P. hondurensis |
4. P. strobus var. chiapensis |
5. P. oocarpa |
6. P. oocarpa |
16. P. rudis |
|
4. P. strobus var. chaipensis |
5. P. oocarpa |
6. P. montezumae |
6. P. montezumae |
20. P. hartwegii |
|
|
6. P. montezumae |
7. P. pseudostrobus |
7. P. pseudostrobus |
|
|
|
7. P. pseudostrobus |
8. P. michoacana |
8. P. michoacana |
|
|
|
8. P. michoacana |
9. P. lawsoni |
14. P. patula |
|
|
|
9. P. lawsoni |
10. P. pringlei |
15. P. ayacahuite |
|
|
|
10. P. pringlei |
11. P. herrerai |
16. P. rudis |
|
|
|
11. P. herrerai |
12. P. douglasiana |
17. P. cooperi |
|
|
|
12. P. douglasiana |
13. P. tenuifolia |
18. P. duranguensis |
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|
22. P. leiophylla |
14. P. patula |
20. P. hartwegli |
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15. P. ayacahuite |
21. P. flexilis |
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22. P. leiophylla |
22. P. leiophylla |
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23. P. lumholtzii |
23. P. lumholtzii |
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26. P. teocote |
24. P. greggii |
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25. P. teocote |
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26. P. cambroides |
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27. P. pinceana |
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28. P. nelsoni |
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29. P. chihuahuana |
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30. P. engelmanii |
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31. P. arizonica |
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32. P. reflex |
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FIGURE 4. - A natural stand of Pinus merkusii in the mountainous regions near Dalat, Viet-Nam.
Asia
India
P. radiata, P. pinaster, and P. maritima have been planted in small plantations in the Nilgiri Hills. Although they are promising in the earlier stages, they do not thrive well. P. pinaster is moderately successful at about 7,000 feet (2,100 meters) in the Himalayas. P. sylvestris (Scots pine), was tried at 8.000 to 9,000 feet (2,400-2,700 meters) in the Himalayas, but was not successful. Successful small-scale introductions are reported of P. canariensis, P. halepensis in Kashmir; P. hondurensis, P. radiata in Assam; P. patula, P. pinaster, P. taeda and P. laricio in the Punjab.
Ceylon
P. canariensis has been tried at 4,000 to 6,000 feet (1,200 to 1,800 meters) and is also successful on alluvial sandy loam up to 400 feet (120 meters) elevation. This species can stand A lower rainfall than any other conifer - 5 to 15 inches (127-380 millimeters) of rainfall, chiefly in winter - and is not affected by frost. It has a mean height growth of 1 ½ feet (46 centimeters) per annum, and is the most successful pine introduced so far.
P. excelsa has been introduced at 6,000 feet (1,800 meters) with fair results; it has a slow early growth.
P. longifolia, introduced at 6,000 feet (1,800 meters), seems promising.
Malaya
P. insularis (Benguet pine). With seed from the Philippines, these trees attain an average height of 7 ½ feet (2.3 meters) and maximum 13 feet (3.9 meters) in 2 years from planting - very promising. Trees in plantation at Cameron Highlands (4,800 feet or 1,440 meters) are reported to have reached 96 feet (29 meters) in height and 5 feet (1.5 meters) girth breast height in 24 years Growth, rapid in early stages, has somewhat fallen in recent years; Home saplings die from attacks of Armillaria mellea.
P. caribaea. From seed from British Honduras - elevation 1,800 feet (540 meters) this is found to be the fastest growing pine in the lowlands with excellent survival rate (94 percent). It has a maximum height of 22 feet (6.7 meters) in 3 years; a most promising species.
P. elliottii. A related species of P. caribaea from subtropical region, it is a failure in lowlands, though survival is good for several years.
P. merkusii. With seed from Sumatra, this species produces indifferent results although rapid early growth. Seeds from Java give better results and grow well in Imperata grass on degraded agricultural land.
P. massoniana. With seed from Hongkong, the species starts poorly and grows more slowly than others. Growth in Imperata grass has improved recently and trees are growing at an even rate with tendency to develop long, unbranched leaders.
Borneo
P. khasya. A failure at low altitude.
P. massoniana. A failure.
Oceania
Tropical Australia - Queensland
P. leiophylla. This species has proved hardy to extremes of heat and moisture.
P. longifolia. Plantations are very promising; seedlings are difficult to transplant after about 8 months, and the best results are obtained with plant 1 or 2 months old transferred to tubes.
P. merkusii, P. montezumae. Both those species have been successfully introduced in Queensland.
P. taeda, P. patula, P. elliottii, P. radiata, P. palustris, P. hondurensis are established, while P. pinaster, P. insularis, P. strobus var. chiapensis, P. tropicalis are thriving.
Fiji
P. hondurensis. P. elliottii, and P. taeda are promising, but trials with P. khasya, P. massoniana, P. patula, P. radiata have resulted in failure.
Africa
South Africa
P. ayacahuite. This species proves hardy and fast growing in moister sites with 20 feet (6.1 meters) average height in 10 years.
P. canariensis. It has been extensively planted since 1898 en sandy and clayey loams over sandstone, granite and dolerite, chiefly on mountain slopes, the original vegetation consisting of grasses, heaths and bracken. This species is fairly hardy and resistant to snow, but frost-tender when young; its mean annual height growth is 1.5 to 3 feet (46 to 91 centimeters) and the mean annual volume production per acre is 100 to 250 cubic feet (2.8 to 7.1 cubic meters).
P. caribaea - Introduced in 1919, this species has been planted extensively on deep loamy sand near the coast; on mountain slopes and foothills on sandy and loamy soils over sandstone, granite, dolerite, quartzite. It is fairly frost-resistant, has a mean annual height growth of 3.5 feet (1 meter) and shows vigorous growth in both temperate and subtropical humid zones, withstanding well strong weed growth and swampy conditions.
P. excelsa. This species has done rather well in plantations attaining a mean height growth of 50 feet (15 meters) and a mean diameter of 10 inches (25 centimeters) in 27 years.
P. cembroides. These pines with edible seeds from Mexico grow at a temperate altitude; although growth is along, it is hardy and promising.
P. gerardiana. Tried extensively this species has proved hardy and promising.
P. halepensis. Plantations started as early as 1893 are thriving well, grown on sandy soils containing lime near the sea coast, and elsewhere on non-acid soils formed from sandstones, shales, dolerite. The species does not thrive on sour soils or in the higher, colder parts; it is useful for limestone soils in drier areas both near the coast and in the interior, and is comparatively resistant to white ants while it is able to withstand drought and frost. Its mean height growth is 2 feet (61 centimeters) and volume production of 150 cubic feet per acre (10 cubic meters per hectare).
P. khasya. Introduced as early as 1884, there are several plantations which are very promising and likely to be of commercial importance. Its mean annual height growth is 2 to 3 feet (61 to 01 centimeters) and mean annual volume production 150 to 200 cubic feet per acre (10 to 14 cubic meters per hectare).
P. insularis. Likewise this species from the Philippines is also thriving well.
P. leiophylla. There are extensive plantations; very promising.
P. longifolia. Introduced as early as 1873, the older plantations date from 1908; it is best grown on loams and sandy loams or on grassy mountain slopes with bracken; snow-resistant, frost-hardy, and drought-resistant.
With mean height growth of 2 feet (61 centimeters) and annual production of 150 to 200 cubic feet per acre (4.2 to 5.7 cubic meters per hectare) it is considered one of the most reliable pines for the afforestation of drier sites in cool and warm temperate summer rainfall areas, but incidence of spiral grain has brought the timber into disrepute.
P. lumholtzii. Very promising.
P. maritima. Successfully introduced and raised since 1890, it is the most reliable species for general afforestation of poor sandy soils in the temperate winter and all-the-year-round rainfall zones. Generally it is not well suited to summer rainfall conditions owing to hail and is unsuited to subtropical conditions because of fungus diseases.
P. merkusii. Thriving in hot, humid areas.
P. montezumae. One of the fast-growing species in South Africa, it has proved hardy to drought and frost.
P. elliottii. This species is now established; it is noted for its freedom from serious diseases and pests and its exceptional adaptability to climate and soil conditions.
P. patula. Most widely planted, this species prefers cool mountain areas with high rainfall and frequent mists in Africa.
P. pinaster. This established species is especially useful on poor sandy soils of mountainous slopes.
P. pseudostrobus. Although established in cool, moist sites in summer-rainfall areas, the timber is not in great demand.
P. radiata. An established pine but one susceptible to damage by hail and subsequent infection by Diplodia pinea.
P. taeda. Although established, it is inferior to P. patula, P. elliottii, P. radiata.
Kenya
Early attempts with all Pinus species failed owing to lack of appreciation of necessity for mycorrhyzal inoculation, but subsequent plantings after importation of 'pine-soil' have resulted in phenomenal successes with species such as P. canariensis, P. caribaea, P. halepensis, P. leiophylla, P. montezumae, P. radiata, P. patula, P. ayacahuite, P. oocarpa. These species are planted at 6,000 to 9,000 feet (1,500 to 2,700 meters) with 40 to 60 inches (1,000 to 1,270 millimeters) rainfall.
Nyasaland
P. cembroides, P. taeda, P. pseudostrobus, P. canariensis, P. montezumae, P. elliottii, P. patula have been successfully established at 3,000 to 7,500 feet (900 to 2,250 meters) with 40 to 110 inches (1,000 to 2,800 millimeters) rainfall and are very promising, while P. longifolia has been established at 2,500 to 3,600 feet (750 to 1,060 meters) with 30 inches (700 millimeters) rainfall and is promising. Indifferent results have been obtained with P. caribaea and P. leiophylla.
Rhodesias
P. canariensis. This species grows best in Southern Rhodesia at altitudes of 5,000 feet (1,500 meters) and over with a rainfall of 36 inches (890 millimeters) or more.
P. halepensis. Thriving well at altitudes of 3,000 to 5,000 feet (900 to 1,500 meters), the species needs a rainfall of up to 36 inches (890 millimeters).
P. longifolia. In Southern Rhodesia it grows beat at altitudes of 5,000 feet (1,500 meters) and over with a rainfall of 36 inches (800 millimeters) or more.
P. elliottii, P. montezumae, P. patula., P. radiata and P. taeda are established at 3,500 to 6,500 feet (1,050 to 1,960 meters) with a rainfall of 40 to 100 inches (1,000 to 2,540 millimeters) P. taeda is unusually free from pests, while P. radiata is attacked by Diplodea pinea.
P. insularis. Although established, this species is not yet grown extensively.
Nigeria
P. longifolia. A failure.
Tanganyika
P. patula. This species is established at 4,000 to 8,000 feet (1,200 to 2,400 meters) with a rainfall of 40 to 80 inches (1,000 to 2,000 millimeters).
P. radiata. Established at 4,000 to 7,000 feet (1,200 to 2,100 meters) the species requires a rainfall of 30 to 50 inches (760 to 1,270 millimeters).
Uganda
P. patula. The species thrives at an altitude of over 4,500 feet (1,350 meters), with 40 to 75 inches (1,000, to 1,900 millimeters) rainfall;
P. radiata. A thriving species, this is grown over 4,500 feet (1,350 meters), with 40 to 50 inches (1,000 to 1,270 millimeters) rainfall.
Mauritius
P. longifolia. A highly successful species, with plantations dating from 1910 - between 800 and 1,500 feet (240 to 450 meters) in elevation - where it is grown on stiff clay and laterite. It is useful in dry localities and on stiff sterile soil where most species fail. It cannot stand a heavy rainfall and has failed at 1,800 feet (640 meters) with 125 inches (3,200 millimeters) of rainfall.
P. massoniana. Successfully introduced in 1885 in different situations above 1,000 feet (300 meters), this species does best on clay and lateritic soils with sufficient moisture. The rainfall averages 58 inches (1,470 millimeters), wed distributed with high atmospheric humidity; it can stand drought. Its mean height growth is 2 feet (0.6 meters) and its mean annual volume production per acre over 100 cubic feet (7 cubic meters per hectare).
Caribbean
Trinidad
P. hondurensis. The species thrives and grows very fast with 80 to 110 inches (2,032 to 2,794 millimeters) rainfall; there are no altitudinal limits. Its growth rate is over 20 feet (6.1 meters) in 4 years.
References occur in the above notes to Pinus radiata Any account of the introduction and establishment of exotic pines would not be complete without mention being made of the role played by P. radiata in Chile or in New Zealand, although these countries are situated outside the region with which this paper is concerned. Like P. canariensis, the natural occurrence of P. radiata is restricted to a very limited range but it likewise has been successfully introduced under a wide range of conditions.
From an unimportant position in its native home of Southern California, where people would hesitate to use it even for fuelwood, it has in New Zealand, for instance, become the major general utility timber for housing and constructional uses, and as raw material for pulp and board industries. Increasing acreages in New Zealand are being planted in admixture with other pines like P. nigra, P. ponderosa, P. strobus and P. contorta.
Nursery and planting techniques
Seed is usually sown broadcast in a seed-base, where protection against rain and sun can be controlled. Protection against ants and other insects is also necessary. After germination when the seedlings are 2 inches high, they are transferred to a prepared nursery bed previously inoculated with mycorrhiza or, if possible, mixed with soil from a natural pine forest. This is absolutely essential to the success of planting on new sites. Shade and protection against heavy rain should be available, with facilities for watering in the dry season.
Seedlings are planted out 3 inches apart in lines. Damping-off is usually prevented by a sprinkling of Hand on the surface, and also by spraying with Bordeaux mixture. In the case of hardy species with short roots, the plants may be pulled out when 8 to 12 inches high for planting out in the field ad naked rooted stock. With long-rooted, difficult species, it may first be necessary to sever the long roots by pulling across a piano-wire under the nursery bed. A 3-inch (7.6 centimeter) square of earth is cut round each plant and transplanting is carried out with a ball of earth. Where the planting-out site is deficient in nutrition, creasing each balled plant with about 3 ounces (85 grams) of superphosphate gives good results.
TABLE: 4. - CLASSIFICATION OF SOME TROPICAL PINES ACCORDING TO NUMBER OF NEEDLES IN A FASCICLE AND IN TERMS OF RESIN AND EDIBLE SEEDS
|
5-needled pines |
3-needled pines |
2-needled pines |
With variable numbers |
With edible seeds |
From which resin is obtained |
|
P. montezumae |
P. patula |
P. halepensis |
P. tabulaeformis |
P. gerardiana |
P. longifolia |
|
P. pseudostrobus |
P. khasya |
P. massoniana |
P. cembroides |
P. cembroides |
P. merkusii |
|
P. armandi |
P. canariensis |
P. merkusii |
P. lawsoni |
P. armandi |
P. khasya |
|
P. excelsa |
P. longifolia |
|
P. hatwegii |
P. pinea |
P. montezumae |
|
P. ayacahuite |
P. greggii |
|
P. oocarpa |
P. cembra |
P. chihuahuana |
|
P. flexilis |
P. radiata |
|
|
P. pinceana |
P. oocarpa |
|
P. leiophylla |
P. gerardiana |
|
|
|
P. teucote |
|
|
P. nungeana |
|
|
|
P. leiophylla |
|
|
P. lumholtzii |
|
|
|
|
As regards the preparation of the site, if planting can be done in conjunction with taungya, so much the better; but usually it has to be done on dry, shallow, porous, infertile soils or grasslands unfit for agriculture, in which case planting must be done into prepared or dug holes of sufficient size to take the roots. Spacing varies according to site and species, but 6 x 6 feet (1.8 x 1.8 meters) is a pretty general rule with a trend towards wider spacing of 8 x 8 feet (2.4 x 9.4 meters) or 9 x 9 feet (2.7 x 2.7 meters) in recent years.
Stand treatment
Weeding may be necessary for the first three years but, after establishment, a plantation can usually withstand considerable competition from weeds or rank growth of grass. For good timber production, a few green-pruning operations up to a certain height of stems are required during the life of a stand for some species. First thinning is necessary from 4 to 10 years of age, depending on original spacing, locality and species. Subsequent thinnings are generally carried out on the basis of marking select trees which are to be retained as the final crop and removing the rest in stages.
Fire protection should be carried out but if, for reasons of lack of funds or personnel, it cannot be enforced, prescribed controlled burning should at least be carried out not only to reduce fire hazard but also to control hardwood invasion where it may occur. Within the range of the occurrence of pines in the tropics, hardwood invasion is not so serious a factor to be reckoned with as in the case of pine forests of higher latitudinal belts in temperate countries, and pine regeneration springs up readily in openings and with fire protection.
In harvest-cutting operations, clear-felling followed by burning of the debris and artificial regeneration by planting is widely practiced. The seed-tree method with natural regeneration, that is, clear-felling except for leaving a few scattered trees per acre, is also feasible and has been adopted in many countries, while a uniform shelterwood system with two or three regeneration fellings carried out at a few years interval, have also proved satisfactory with most species. After harvest-cuttings, controlled burning is beneficial for the preparation of the site, which should subsequently be protected from fire and grazing for at least ten years after the new crop is established, whether by artificial or natural regeneration.
Pines are essentially strong-light-demanding species, and on this silvicultural characteristic arc based moat of the cultural operations.
Pests and diseases
Pines am known to be subject to numerous fungal and insect pest attacks, which are liable to make their appearance on trees damaged by lopping, hail, storm, etc., or on weak trees grown on difficult sites. Although some may cause widespread destruction, many are of little more than local importance.
Fungi. Among the fungal pests, rust fungi caused by Peridermium spp. (syn. Cronartium spp.) are in a class by themselves, attacking five-needled pines moat readily. They attack the needles, branches and stems, causing galls and tumors. Their occurrence is reported from Central America, while in India P. longifolia and P. excelsa are extremely susceptible.
Trametes pini and allied species are next in the order or equally important, having been reported from all coniferous regions of the world. Trees of all sizes are attacked and the usual signs are the rotting and disintegration of the heartwood, making the timber more or less valueless and the trees liable to be broken by wind, and the appearance of the sporophores on stems or exposed roots, at points where the wood has been exposed by some physical injury. Preventive and remedial measures may consist of prevention of lopping, cutting and other forma of injury, felling trees at or below ground level, covering the stumps with earth or burning them together with all infected debris and branches, and removal in thinnings of trees damaged by snow or other causes.
Diplodia pinea is the cause of considerable concern, notably in South Africa, where extensive damage to species like P. radiata, P. patula. P. canariensis and others is caused by the fungus gaining ingress after injury by hailstorms.
Among the fungi of lesser importance, which locally may kill many trees by attacking the roots or the portion of stem immediately above the roots, may be mentioned Armillaria mellea, Trametes radiciperda, Rhizina inflata and Fomes annosus.
FIGURE 5. - Pinus patula in the Republic of Mexico.
Courtesy, Prof. Maximino Martinez
In general, comparatively very little is known of fungus diseases in Latin America.
Bluing or blue stain of pine wood, especially in sapwood, id caused by a fungus agency and is a common cause of complaint all over the world. The spread of the fungus is known to be facilitated by ambrosia beetles. Merulius lacrymans, commonly known as the dry-rot fungus, is often responsible for decay of timber in contact with the ground or where there is no free circulation of air.
Insects. Cerambycid wood-borers of Acolesthes and Baralipta spp. attack P. insularis in the Philippines; in Central America P. hondurensis is subject to Ips beetle attack, while in Guatemala, attacks of the engraver beetles Dendroctonus adjunctus and D. mexicana have destroyed extensive areas of P. rudis forests. Among some of the other most destructive insects may be listed Hylobius abietis (pine weevil) which destroys young plants; Myclophilus piniperda (pine bark beetle), Rhagium spp. (pine longicorn beetle) and the Pissodes spp. (banded pine weevils) which cause injury by the larvae feeding on the cambium.
Pine sawflies (Diprion and Neodiprion spp.) also cause injury by their larvae feeding on the leaves. Pine-shoot Tortrix moth and Resin-gall tortrix moth (Evetria spp.) are common shoot-borers which may attack both young and old trees alike, while there are several species of moths (Bupalis, Sphinx spp.) which feed on leaves. Defoliation is also caused by locusts and Euproctis terminalis, and control measures consist of hand-picking or aerial dusting.
Wood wasps (Sirex spp.) are known to attack living trees, while white scale insects (Chionaspes spp.) and Aphides (Adelges spp.) are conspicuous as white covering on stems, leaves and cones. In some countries, termites are known to damage the base of trunks.
Possible control measures consist of hand-picking, spraying, aerial dusting, preservation of insect-eating birds and correct cultural methods.
A few species of tropical pines stand out and at once suggest themselves as deserving attention and introduction trials by virtue of their desirable qualities, such as superior growth characteristics, timber properties, adaptability, hardiness, etc. The following are some of such most promising species:
1. P. merkusii, P. hondurensis for wet tropical localities - plains up to 3,000 feet (900 meters);2. P. khasya, P. longifolia, P. insularis for wet tropical and subtropical highlands;
3. P. strobus var. chiapensis for tropical to subtropical localities with 40 to 76 inches (1,000 to 1,900 millimeters) rainfall;
4. P. tropicalis, P. cubensis, P. occidentalis for tropical localities;
5. P. canariensis, the best pine timbers in the world, strong, heavy durable; for dry subtropical climate resembling the Mediterranean type;
6. P. patula, P. durangensis - among the fastest growing large-sized pines of good general utility timbers for subtropical and warm temperate elevational belts with over 40 inches (1,000 millimeters) rainfall;
7. P. ayacahuite, P. pseudostrobus - among the largest and best pine timbers suitable for warm temperate to cold temperate elevational belts with 40 to 75 inches (1,000 to 1,300 millimeters) rainfall;
8. P. montezumae - a large tree though variable; is of wide occurrence and great adaptability from subtropical to cold temperate with over 40 inches (1,000 millimeters) rainfall.
In addition, P. herrerai, P. douglasiana, P. leiophylla, P. michoacana and P. pringlei are among the species which deserve trial and experimentation.
Mention has been made earlier of P. radiata. In conclusion, a passing reference may also be made to P. halepensis, P. maritima and P. laricio, of the Mediterranean region, which hold promise for subtropical areas with a Mediterranean type of climate.
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