Pakistan is an extratropical country between 24° to 37°N latitude and 61° to 75°E longitude. It has four provinces, i.e. Punjab, Sind, Baluchistan and Khyber Pakhtunkhwa (KPK) whereas the status of Kashmir is not yet decided. The north and north- western part of the country is hilly, but the central and southern part mostly consists of alluvial soils and a few deserts. Mean annual rainfall varies from 100 mm in the south to 1,500 mm in the north. The temperature varies from freezing point to 50°C. The important national forestry facts are given in Appendix 1.
Some national facts of forestry of Pakistan
HISTORY OF EUCALYPTUS PLANTING
Its first introduction in the sub-continent dates back to 1843 as single trees, arboreta and roadside plants. In 1900, when it was feared that fungal attack would cause severe loss to ‘shisham’ (Dalbergia sissoo) in irrigated plantation, interest in Eucalyptus rose. However, no substantial areas were planted till 1950 as it was not considered a useful species due to shakes and cracks which developed in the cut wood. Efforts to test more Eucalyptus
species revived with the arrival of Mr. G. Brockway, an Australian expert in 1955. Many foresters visited Australia in the quest of suitable species for climatic conditions obtaining in Pakistan. In the process, arboreta were established in the plains (Pirowala, Changa Manga, Mianwali, Chichawatni), and in hilly areas (Ghora Gali, etc.). Field trials on small scale were also conducted at Fort Munro, Pirowala, Changa Manga, Bani (Gujrat), Pakhowal, Jauharabad and Rakh Pirsabz.
Pryor (1967), an FAO consultant, assessed work here on Eucalyptus. In his opinion it was futile to test scores of species and suggested that future trials may be confined only to the following five species in order of merit: Eucalyptus tereticornis; E. camaldulensis; E. microtheca; E. melanophloia and E. citriodora. He further suggested that seed collection of these species should be made from pure stands or isolated trees available in Pakistan to minimize the chances of hybridization. In a study, “Past performance and future prospects for the use of Eucalyptus in Pakistan”, he recorded (Appendix 2) the performance of species and localities where they are growing. In the seventies the planting programme of Eucalyptus received a new impetus. Sheikh (1981a) found Eucalyptus camaldulensis could be raised without irrigation in the Peshawar zone when planted during the winter rains. (Mean annual rainfall of Peshawar is 400 mm of which 60% falls in winter). In 1985 the Social Forestry Project was started to motivate the
farmers of seven districts (Attock, Rawalpindi, Jhelum, Gujrat, Khushab, Chakwal and Sialkot) of Punjab to raise fuelwood plantations mainly of Eucalyptus.
EUCALYPTUS SPECIES IN PAKISTAN
Eucalyptus is being grown in irrigated plantations of the Government land and on farmlands of Punjab and Sindh. A recent survey shows about 200 million trees are planted in the Punjab on farmlands, mostly irrigated, of which Eucalyptus is 2.2%. Similarly a survey in KPK Province found about 80 million trees were raised on farmlands, mostly irrigated, of which total Eucalyptus was 2.7 % (Amjad 1991, 1992). Under the Social Forestry Project,
the farmers have raised 28 million trees since 1985. These trees if considered to be planted at 3 x 2 m, which is the conventional method, will cover an area of 16,800 ha, including 470 ha with Eucalyptus. The largest plantation of eucalyptus in pakistan is at Khipro (Sindh). Eucalyptus camaldulensis project planting commenced in 1973 to provide raw material to pulp and paper, chipboard and furniture industries. To date, about 3,500 ha
have been planted.
In the technique, one year old plants are raised in polythene containers in the nursery. These are planted at 1.5 x 1.5 m spacing in trenches during February and March. Restocking of failures is carried out in 2nd and 3rd year of planting. Weedings are made twice in the first year and once in each of the 2nd, 3rd, and 4th years. The rotation of harvest is fixed at 8 years and trees are sold standing through open auction. The plantation is presently in arid areas affected by water logging and salinity. Another large Eucalyptus plantation is in Bahawalpur, of 4,123 ha. Bahawalpur plantation has a sandy loam soil with mean annual rainfall less than 200 mm, mostly received in summer. Summers are extremely hot and dry, with the maximum temperature to 45 oC. Winters are comparatively short but generally severe; lowest temperature is at freezing point. A rough estimate that Eucalyptus plantings cover is about 10,000 ha. Of all Eucalyptus introduced in Pakistan to date, E. camaldulensis has proven most adaptable under all agroecological zones. Consequently, it has been planted more than other species; it is the prescribed species of all afforestation programmes. It is especially favoured in arid and semiarid plains as: single trees, in block and linear plantations and is raised with or without artificial irrigation. The existing growing stock of Eucalyptus is mostly of E. camaldulensis and its numerous hybrid forms, occurring naturally.
Is the river red gum in Australia and sufaida or lachi in Pakistan. It is very large evergreen tree, the bark is usually not straight and is of red gum type, thick, smooth and patchy. The wood has light grey sap and reddish brown heart wood; it is hard and heavy. The species grows under a variety of ecological conditions associated with water courses, hence in the name river red gum. It exhibits a great deal of diversity in morphological features; is frost hardy and a light demander. The best growth in Pakistan is observed on exposed and disturbed sites. Though it coppices very well, this method is not practiced in plantation regeneration.
Eucalyptus produce seed in September and October from five years age. Capsules, sun ripened open and shed seed in a week. Seed per kg of the five important species are: E. microtheca, 200,000; E. camaldulensis, 550,000; E. citriodora, 200,000; E. melanopholia, 250,000; E. tereticornis, 350,000. Seed remains viable for 1-2 years, but if air dried and kept in sealed containers at 1-4°C can remain viable for years. Seed are sown at any time during the year in raised sandy beds. Germination starts within a week. When the seedlings are 5-7 cm high (after about one month), they are pricked out
into polythene tubes. After six months the seedlings are ready for field transplanting. Plant cost is about paisa 25 (Sheikh, 1979).
Height, diameter and volume growth
Figure 1. Average height, diameter and volume growth of thirteen provenances of E. camaldulensis at 10 years
The average height, diameter and volume of 13 provenances of E. camaldulensis grown in Changa Manga irrigated plantation are given in Figure 1. The plantation is characterized by extremes of temperatures, low relative humidity and erratic irregular rainfall of a mean of 378 mm; mean maximum temperature is 41°C and mean minimum temperature is 5.5°C. The plantation is irrigated (Siddiqui, 1984).
Irrigation methods – spacing
Eucalyptus was introduced in Pakistan a century ago. Since then a conventional spacing of 3 x 2 m with trench irrigation has been used in planting. A study commenced in 1976 at five different sites to investigate spacing and irrigation. Two major treatments (trench and flow methods) and three minor treatments (spacings 1.5 x 1.5; 2.25 x 2.25 and 3 x 3 m) were adopted. Analysis of data indicates:
- Major treatments viz. trench and flood methods of irrigation did not have any effect on diameter and height of the trees.
- Diameter increased with the increase in spacing.
- Closest spaced trees gained more height as compared to wide spacings.
- Close spacing (1.5 x 1.5 m) produced 95 m3 wood/ha and wider spacings, 2.25 x 2.25 and 3.0 x 3.0 m – 61 m3/ha and 38 m3/ha respectively at Chichawatni. The same trend was observed at Pirawala and Bahawalpur.
- Wider spacings were heavily infested with weeds compared to closer spacings.
- A first thinning was made at Chichawatni as the crop was congested in the 1.5 x 1.5 m spacing; 35 m3 wood/ha was removed and 60 m3/ha remained which was equal to the volume available in the 2.25 x 2.25 m spacing and about one and a half times that of in the 3.0 x 3.0 m spacing (38 m3).
The study has given very important indications. It is recommended that for maximum volume production on a short rotation, Eucalyptus amaldulensis plantations should be raised at 1.5 x 1.5 m for pole, post and fuelwood production. If desired to be grown on longer rotation, these plantations can be thinned after 5 years to reduce competition and to enable the standing trees to gain diameter (Sheikh , 1984).
The strength properties of plantation grown E. camaldulensis wood in Changa Manga were determined according to British standard specification. The data for eucalypt wood is listed in Figure 2, along with the values for shisham (Dalbergia sissoo) and deodar (Cedrus deodara) for comparison purposes.
The data shows that with the exception of shearing strength, all other properties of E. camaldulensis wood are inferior to those of shisham. The reason for high shearing strength of eucalypt wood is the presence of sloping or interlocked grains which improves its shear strength. The mean values of eucalypt wood are 57-91% of the values for strength properties of shisham. On the other hand Eucalyptus properties are either comparable or superior to those of deodar. The exception is only modulus of elasticity. This suggests that Eucalyptus wood can be efficiently used for all purposes where deodar is presently employed. These uses include, joinery work, cross arms and construction purposes. Although deodar wood has high natural durability against insects and fungi, application of a suitable preservative treatment to eucalypt wood will provide sufficient protection against
attack. Eucalypt wood can substitute for shisham in furniture manufacture provided slight modification are made in its design for lower strength. In general, E. camaldulensis wood can be regarded as fairly hard and strong and suitable for a number of uses.
Figure 2. Comparison of strength properties of E. camaldulensis with shisham and deodar
While comparing the properties of commercial Eucalyptus particle board panels with the commercial board panels, it was observed that although former board is of lower density; its strength properties are better than the commercial panels. The low density in commercial panels is due to an inefficient chip spreading manufacture system. This system was good enough for the raw material used by the industry but it does not suit
eucalypt chips. This is also the reason for the high density coefficient and water absorption values of commercial panels. From the preliminary results obtained, it is concluded that E. camaldulensis wood can produce particleboard of standard requirement provided some water repellent additive is added to the chips.
Figure 3. Crossarm potential of eucalypt
Water and Power Development Authority
Crossarms: The properties of eucalypt wood were superior to standard requirement for crossarms of deodar wood used on electric transmission poles, except for modulus of elasticity, as shown in Figure 3.
Service life of E. camaldulensis crossarms was tested. Green logs were converted into 2.44
m x 12 cm x 2.5 cm size crossarms. They were carefully air seasoned to avoid development of defects. After seasoning, these were treated with 50:50 mixture of creosote and light diesel oil by the full cell process according to the Water and Power Development Authority (WAPDA) specifications; 41 treated crossarms were installed on 11 KW electric transmission poles along Jamrud road, Peshawar 1980 in collaboration with a local WAPDA office.
The crossarms were visually examined in June 1983 and checked for defects: spring, bowing, cupping, twisting, end splitting, surface checks, cell collapse (wash-board effect), insect attack, fungus attack and compression failure. They were graded according to the IUFRO Standard method for stake test. The result is shown in Figure 4.
Figure 4. Crossarm defect test
Seasoning defects, when not severe, hardly affect the strength properties of the crossarms, especially, since WAPDA specifications are based on a safety factor of 5. Some 73% of installed crossarms were found to be serviceable after almost 3 years of installation. There is considerable scope for improvement of their performance through proper seasoning.
Posts (40) each of E. camaldulensis and Cupressus sempervirens were treated with two preservatives – Tanalith C, (2.5% solution by weight) and Pentachlorophenol (5% solution by weight in diesel oil) and 5 posts of each species were taken as control. All fence posts were installed in 1978 in the Pakistan Forest Institute to determine service life. After one year, all the fence posts were examined for decay or at the ground level for beetle
attack there. The result is shown in Figure 5.
Figure 5. Extent of damage on fence posts
The untreated posts of both the species were completely damaged by termites attack and had to be replaced after one year. In the case of Pentachlorophenol, 4 out of 20 posts of eucalypt and 2 out of 20 posts of cypress had partial termite attack at ground level. The reasons for this could either be mechanical to the treated outer surface during installation, providing entry for termites, or due to the leaching of the chemical during rain. In the Tanalith C treatment, none of the 40 posts of either species had any attack at ground level. However, in eucalypt Tanalith C treated, beetle attack above ground level was recorded in one post. The reason for this could again either be mechanical damage to the outer treated shell, or the presence of the insect in the wood prior to the treatment. The overall results indicate that both treatments had a significant effect in prolonging the life of posts of both species. Tanalith C gave better results than Pentachlorophenol. The cost of chemical per post for Tanalith C treatment is about Rs. 0.50 and for Pentachlorophenol about Rs. 2.00.
Firewood and charcoal. Eucalyptus camaldulensis is one of the principal eucalyptus grown for fuelwood over the world. The wood of most eucalypts burns well when air dried and leaves little ash; it carbonizes easily, providing good charcoal. Charcoal yields more calories per kg than raw wood, about 7,900 calories per kg for charcoal against 4,700 calories for wood. Charcoal production, however, uses 1 1/4 to 3 times as much wood to deliver the same amount of energy, as there is considerable loss of energy/heat during conversion into charcoal.
Eucalyptus camaldulensis is quite comparable in calorific value with the commonly preferred fuelwood species of shisham (Dalbergia sissoo) and kikar (Acacia nilotica).
However, the former has slightly lower wood density than the latter; the density of eucalypt wood is 705 kg/m3 , shisham (Dalbergia sissoo) is 801 kg/m3 and of kikar (Acacia nilotica) is 833 kg/m3 . On the other hand considering growth rate of these species, a hectare of eucalypt plantation could produce up to 10.86 tons of air dry of wood per annum which is more than that of shisham (Dalbergia sissoo) (5.21 tons of air dry wood per ha per annum) and kikar (Acacia nilotica) (10.08 tons of air dry wood per ha per annum).
The moisture content in freshly cut wood of Eucalyptus is round 80% and it weighs about 850 to 900 kg per m3 green. It will lose half of its moisture by air drying for 8 weeks in an average dry season which lowers its weight and leaves the wood a good fuel. This has the additional advantage of ease of transporting the lighter material.
SOCIAL ASPECTS OF EUCALYPTUS PLANTING
Pakistan is basically an agricultural country. About 20 million ha (25% of total land area) consists of 4 million individual farms averaging 4.7 ha in size. Farmers prefer to grow multipurpose trees that give fuelwood, fodder, fruits and do not adversely affect agricultural production. The following is a common dialogue which occurs between the farmer and the forest officer during the motivation for planting trees:
Qes. Why shall I plant trees with agriculture crop when it would damage the crop and reduce the yield? The trees send their root system in competition with agriculture crop, cast their shade on the young crops and house birds to attack the crops at grain stage.
Ans. Nobody is asking you to raise trees in competition with agriculture crops. Trees shall be raised on such lands which generally are not fit for raising agri-crops. They can also be raised around agriculture fields, and with agri-crop if it is compatible with the agriculture crop. If properly spaced and planted in appropriate directions, the trees will not damage agriculture crops. Not all birds damage crops, many birds which eat some grain also eat a
lot of insect larvae. The Chinese had to import a lot of insecticide after the complete elimination of spar-rows. If birds or trees become too numerous some can be harvested for the farmers benefit.
Choice of species.
This is great interest to and by farmers. Eucalyptus has been accepted by the farmers mainly because of its phreatophytic qualities and fast growth. Although efforts are on record for encouraging indigenous species by the field staff, the glamour of Eucalyptus seems to caught the public. The trend in favour of Eucalyptus has been gradual from 1985 to 1990 as can be seen in the following Figure 6.
Figure 6. Yearwise % of plants planted by farmers
Eucalyptus has been accepted by almost all farmers for farmland planting. NGOs, such as Agha Khan Rural Support Programme (AKRSP) and Pakistan Foundation of Environmental Conservation (PFEC), do not advocate any particular kind of tree, but do advocate increasing the number of trees. The only apprehension of the farmers who have raised Eucalyptus in large number on their fields is that there is no proper marketing system that
pays back to them: the money invested with reasonable profit. Hopefully the industries will soon start purchasing eucalypt wood as raw material for pulp, paper, plywood and safety match boxes. In fact, two industries have come forth with encouraging results .
Allelopathy. Malik (1993) studied the allelopathic effect of three Eucalyptus species on the growth of french bean (Phaseolus vulgaris) and sweet pea (Pisum sativum). It was found that leaf leachate of Eucalyptus had no significant allelopathic effect on all the growth parameters of french beans. However, the growth of sweet pea was significantly reduced due to allelopathy. The maximum effect was decayed leaves of E. citriodora followed by E.
camaldulensis and E. tereticornis (Figure 7).
Khattak (198l) also observed differences in yield in wheat crops grown between rows of Dalbergia sissoo, Eucalyptus citriodora, Populus deltoides and Salmalia mulbaricum. Wheat yield was higher with Dalbergia sissoo than other three species (Figure 8).
Figure 7. Allelopathic effect
Figure 8. Effect of some tree species on crop yield
Water stress. Saturation deficit and water stress in dry and wet season was studied for three species (Repp et al., 1967). The result is shown in Figure 9.
Figure 9. Water stress
In comparing Olea with Eucalyptus, the saturation deficit of the later is higher than that of Olea during the dry and the rainy season. Since Eucalyptus has a lower dehydration tolerance too, it is percentally under greater water stress than Olea. However, as the water stress of the Eucalyptus does not yet reach the critical point (63-65%), it may be said Eucalyptus can still stand ecological stress conditions without actual damage.
EUCALYPT PESTS AND DISEASES
Eucalyptus plants are highly susceptible to termites in the first two years after planting. The Forest Entomologist, Pakistan Forest Institute, ecommends use of Heptachlor, Chloradane and Dieldrin, 5 cc per plant in 1/2 gallon of water at the time of planting, mixing the insecticide in the soil.
The following important diseases of eucalypts have been detected in Pakistan. Names of the causal agents and control measures are also given in Figure 10.