0459-B4

Growth Behaviour of Some Tree Species in High Density Plantation in Mid Hills of Western Himalaya

Gopi Chand and R.D. Singh 1


Abstract

The study on growth and biomass production of some fast growing tree species for short rotation high density energy plantation was conducted in the agroclimatic conditions of Palampur in the Indian western Himalaya. The objectives of this study were to develop agrotechniques for raising fast growing fuel-wood species to reduce pressure on natural forests; and to educate rural community to raise such plantations for improving their socio-economic status.

The observations on vertical and radial growth, fresh biomass and dry matter production were recorded up to 72 months after planting (MAP). The study involved three factors viz., plant species (10 No.), plant spacing (2 types) and doses of NPK fertilizers (4 doses). At 24 MAP, the effect of fertilizers was more evident in terms of vertical growth than radial growth. The plant height showed an increasing trend with increase in fertilizer doses. The highest plant height was recorded in Eucalyptus hybrid followed by Populus deltoides, while Salix tetrasperma showed the poorest vertical growth. In terms of stem diameter, Eucalyptus hybrid was the best species followed by Grevillea robusta and Trewia nudiflora. Application of N:P2O5:K2O::150:75:75 kg/ha provided thicker stem in comparison of the lower fertiliser doses. At 36 MAP, G. robusta produced significantly highest vertical growth followed by Jacaranda acutifolia and Eucalyptus hybrid, while Bauhinia variegata showed significantly highest radial growth followed by Eucalyptus and G. robusta. Except G. robusta, Toona ciliata and Morus alba, the lowest fertiliser dose (50:25:25 kg/ha) provided significantly highest vertical and radial growth rate, at 36 MAP.

At 36 MAP, significantly highest fresh and dry biomass (oven dry) per plant was produced by Eucalyptus followed by G. robusta and Melia azedarach. The maximum dry weight (62%) was recorded in case of M. alba. At 72 MAP, the significantly highest fresh and dry weight per plant were recorded in Eucalyptus followed by G. robusta, T. ciliata and M. azedarach. Amongst the plants not treated with fertilizers, the highest fresh and dry weight were obtained from G. robusta planted at 1m x 1m spacing. The same species when planted closer at 1m x 0.71m spacing was comparable to Eucalyptus. Amongst all the test species, G. robusta had highest calorific value (25.76 kj/g in wood, 26.17 kj/g in bark). The parameters under this study reveal that Eucalyptus and G. robusta were unaffected by the adversities of the environment, while S. tetrasperma was most vulnerable species.


Introduction

In India, forests occupy about 19.4 % current requirement of total (11.7% dense, 7.6% open and 0.1% mangrove) of the total land area, which is insufficient to meet 140 million tonnes per year of fuel wood (FSI Report, 1991). Attempts are, therefore, being made to increase the bio-energy conservation through the short rotation high-density energy plantation of the fast growing species. Firewood constitutes 68.5% of the sources of energy used in India and 64.2% of its collected from natural sources (Khosoo, 1984). The main source of energy is biomass - the vegetative material produced by plants. Thus, production of fuel-wood under short rotation high density (SRHD) energy plantation culture should prove useful for meeting challenges of fuel wood crisis, especially in the rural areas. A large number of fast growing exotic as well as local species are now being selected for this purpose over the slow growing and less valuable indigenous species. On the socio-economic front, SRHD energy plantation provides help to rural population, particularly to women. The time lost in collecting fuel-wood from forest sources can be saved and utilised for caring the families at home as well as for some income-generating activities.

In the north-western Himalayan region, there is lack of adequate information on raising SRHD energy plantation, particularly under the agroclimatic condition of Palampur. Since the success of the SRHD energy plantation lies in the production of high yield of good quality fuel- wood within a short rotation period (5-6 years) in sharp contrast to the long period (15-30 years) required to produce the same yield by conventional forestry. There is a strong argument for undertaking research on SRHD energy plantation to develop a sound and economical technology for the north-western Himalayan region. The present paper deals with the growth and bio-mass production of some selected fuel wood tree species under the effects of fertilizers doses (N: P: K) and plant density, with special reference to calorific value of test species.

In India, the economic and political pressure, deforestation, forest fire, conversion of forest land into intensive agricultural land, industrial establishment, new residential programmes, roads and other commercial activities are causing reduction of the forest area every year.

Materials & Methods

The present study has been conducted at the experimental farm of IHBT, Palampur located at 1300 m above msl, at 32 o 06'N and 76 o 03' E in district Kangra, which encompasses the sub-mountain low hills, subtropical and middle hill sub-humid zones of the Dhauladhar Himalayas. The area of Himachal Pradesh is 5,063 sq Km Forest area is about 39% of the total area, however the net area shown is only 21.2 %.

The experiment was laid out as per "Split Plot Design". Ten species of fuel-wood tree were taken as the main treatment. Two spacing S1 (1mx1m) having 10,000 plants/ha, S2 (1mx0.71m) having 14,000 plants/ha, were sub-treatments, and four levels of fertilizer (N:P:K) doses were sub-sub treatment. Each treatment was repeated thrice.

The test growing species were planted in 1993. All the saplings were 10 to 12 months old at the planting time. The meteorological parameters of seven years (1993 to 1999) showed average annual rainfall of 1985.5 mm. The mean minimum and maximum temperatures were recorded in January (5.6 o C) and June (29.4 o C), average relative humidity was 57%, and solar insulation was 6.96 hours/day. The analysis report of soil showed that the soil possessed medium fertility status and pH 5.23, organic matter 2% and available Potassium (183.3 ppm). Soil was low in available phosphate status (15.86 ppm) and the physical characteristics showed that the soil is clayey loam.

The main test species were as follow:

1.Grevillea robusta Cunn 2. Jacaranda acutifolia Humb & Bonpl 3. Melia azedarach Linn 4 Salix tetrasperma Roxb 5. Eucalyputs sp. (hybrid) 6. Bauhinia variegata Linn 7. Toona ciliata Roem 8. Trewia nudiflora Weight 9. Populus deltoides Marsh (clone G-3) 10. Morus alba Linn.

Sub-treatments (2 spacings): S1 (1mx1m) and S2 (1mx0.71m).

Sub-sub treatments (4 NPK doses): 0:0:0(F1); 50:25:25(F2); 100:50:50 (F3) and 150:75:75 (F4)::N2:P2O5:K2O kg/ha.

The observations on growth parameters were recorded from 3 months after planting, and were recorded at quarterly intervals. The irrigation by rose can was done as or when required especially in the dry season upto 1 year. Some physiological parameters viz. rate of photosynthesis, stomatal conductance/resistance (data not shown) etc. were recorded using a portable photosynthesis system (IRGA) model L1-6200, LI-cor, inc, USA , water potential was recorded with a plant water status console, made in USA (data not shown). The chlorophyll fluorescene (Fv/Fm) parameters were also measured using plant stress meter (PSM Mark II, Biomonitor, Swedon). The sub-subplots were treated with fertilizer doses of NPK (a) 0:0:0 (F1); 50:25:25(F2); 100:50:50 (F3) and 150:75:75 (F4) kg/ha. The fertilizers were applied around each plant in the month of March every year, up to 3 years. The area of unit plot was 193m 2 , sub plot was 96m 2 and of sub-subplot 24m 2 . At 36 and 72 months after planting (MAP), 10 plants per sub-subplot were selected for harvesting. Observations were recorded on vertical and radial (stem diameter at ground level and breast height) growth of all the test species. The above ground portion of each harvested plant was divided into three equal parts, on the basis of standard growth parameters. The fresh and dry weight were measured. For dry weight, the plant material was dried at 70 o C in the oven till constant mass.

The data were analysed for percentage increase in growth at 12, 24, 36, 48 and 72 months over previous growth. Vertical growth (plant height) was recorded from the ground close to the plant collar, radial growth was measured at 2 cm above the ground (collar diameter) using the Mitutoyo (Japan) slide caliper upto 0.02 mm accuracy. Similarly, diameter at breast height was also measured. The diameter were measured on the northern and southern sides of the collar and the mean of these was recorded. These three observations were taken at 3 months intervals, commencing from December 1993. The data were subjected to analysis of variance as per five samples (stem bole, branches, twigs and bark) of each species were analysed. Their weight and volumes were measured and all the samples were dried at 70 0 C in an electric oven to get constant weight to estimate the moisture content. Samples were ground in an electric mill to pass through a 0.1mm mesh sieve and pelleted. The pellets of 1.0 gm each were burnt in an Parr oxygen bomb calorimeter to calculate the calorific values. The powdered samples of stem wood and bark (1.0 gm) was burnt in a muffle furnace at 550 o C for 4-6 hours and the residue was weighed as ash content. The usable (stem, branch and bark) and total energy content of the plant were obtained by combining the biomass and their energy values. Wood density of the stem (2.5 cm diameter) was determined by weight loss of 1.0 cm thick disc under glycerin. Fuel value index was computed by multiplying the usable biomass per unit area with density and energy which was divided by age of the plant.

Result and Discussion:

Vertical and Radial Growth: In case of the vertical growth, during the first 2 years significantly highest vertical growth was recorded in G. robusta, followed by E. hybrid and J. acutifolia. At 36 months in 1996, G. robusta and E. hybrid showed significantly highest growth followed by B. variegata and J. acutifolia (Fig. 1). At 72 MAP, significantly highest vertical growth was recorded in J. acutifolia followed by T. ciliata and B. variegata (Fig. 1). At 24 MAP, significantly highest radial growth was obtained in E. hybrid followed by G. robusta, B. variegata and J. acutifolia respectively. At 36 MAP, E. hybrid was significantly better in terms of radial growth followed by G. robusta and B. variegata (Fig. 2). At 72 MAP, the significantly maximum radial growth was recorded in J. acutifolia, B. variegata and T. ciliata, both were statistically parallel in terms of radial growth.

In terms of breast height diameter, the data recorded in 1994 & 1995 was not significant. The species were not at the breast height level in terms of breast height diameter (d.b.h.). The rate of increment in diameter at breast height was significantly highest in T. ciliata (297.1 %) (Fig. 3). The B. variegata also comes under first category on the basis of the statistical analysis. J. acutifolia, T. nudiflora and M. azedarach proved significantly superior to P. deltoides in terms of diameter at breast height (Fig. 3).

Plant spacing: Different spacings evaluated under this experiment had no significant influence on vertical and radial growth rates during the initial 24 months and also at 36 and 72 MAP (Table 2). In terms of diameter at breast height, significantly higher increment was observed with 1mx1m spacing (Table 1).

Fertilizer doses: All the fertilizer doses resulted in significantly higher vertical growth rate over control (F1), though the differences between F2 and F3 as well as between F3 and F4 were similar. Between 1993 to 1996 the F2 showed the highest vertical growth in comparison of F3 and F4. During December 1996 to December 1999, there was no clear cut difference in vertical growth between all the fertilizer doses. In terms of radial growth, a trend was obtained in increasing order towards F1 to F4. However, these parameters were not statistically significant at 72 MAP.

Biomass: The fresh and dry biomass was recorded at 24, 36 and 72 MAP. The significantly highest fresh biomass was recorded in Eucalyptus at both the spacing using lowest fertilizer dose F2 (50:25:25:NPK, kg/ha) at 36 MAP. Even at 72 MAP, the significantly highest fresh weight per plant was recorded in F2 fertilizer dose. However, all the fertilizer doses were statically significant over control at 72 MAP. In the same way E. hybrid showed hightest fresh biomass per hectare (811.1 t/ha) at 72 MAP, the same pattern was followed in case of dry weight (437.1 t/ha) (Fig. 6). In terms of fresh and dry weight of bark, E. hybrid showed significantly highest weight followed by G. robusta (Fig. 6). The dry matter (wood content) was also measured for all the test species at 36 and 72 MAP. M. alba was the best species in terms of dry matter content, 65.6% J. acutifolia, M. azedaraels and G. robusta showed parallel dry matter content 60.1, 60.0 and 59.6%,at 72 MAP.

The calorific value of test species varied from 20.22 to 25.76 ki/g in stem bole, 21.18 to 26.82 ki/g in braches and 20.05 to 26.17 ki/g in bark of the test species. These values in association with biomass indicated the potential energy content per unit area as a renewable resource. The calorific value was maximum in G. robusta (25.76 ki/g dry weight) wood samples. In order to screen out the species for their suitability for fuel wood purposes, fuel value index was derived by combining a few important fuel wood characteristic. As per our studies, especially in the analysis of dry matter content, a species superior in biomass production may not essentially turnout to be as good in aggregate properties. For an ideal fuel wood in addition to other combustion properties high heat of combustion, high density of wood, low ash and low water content, are most desirable characters. In our investigations, the lowest water content was recorded in M. alba (36 to 38%), while the highest water content was recorded in S. tetrasperma and E. hybrid followed by B. variegata ranging from 61 to 66 %, at 36 MAP. The fresh and dry weight of bark (excluding foliage) and the water content of the bark of each species were also studied.

Two type of growth pattern have been widely recognized in temperate trees viz., rhythmic and episodic. When recurrent leaf flushes occur at regular intervals, the growth is termed as rhythmic or periodic and the same occurring at irregular intervals is called as episodic type of growth. In the present investigation, out of the 10 species studied, Except Eucalyptus hybrid and G. robusta, remaining eight species have shown the rhythmic growth system.

The plant species survival is closely affected by whole plant response as determined during earlier stages of the dehydration cycle. The different pattern of survival was directly related to the maintenance of leaf area and hydraulic conductivity of xylem tissues. Muchow and Sinclair, 1989, Sinclair and Ludlow 1986 and Sinclair et al 1987, have reported that the leaf loss is generally associated with runway xylem embolism and high cuticular water losses in plant species.

In our observations, the wider spacings showed significantly highest diameter at ground level and also at breast height. The fresh and dry weight was significantly highest with close spacing in comparison of wider spacing. Our results fully agree with the observations of Misra et al 1996. The mean annual increment in d.b.h. was lower with higher plant densities and reduction in the plant density increased the mean annual increment in d.b.h. and the basal area tree -1 . The reduction in survival and growth with high density was due to the early competition within stands for mineral nutrients (Cole and Newton, 1986), soil water (Bassett, 1964) and light (Kozlowski et.al. 1991). Similarly, Parrotta (1988) had reported reduction in tree growth in the higher density stands of sirirs. On the other hand, increased tree growth with low density plantation might be due to higher availability of light, water and nutrients resulting increase in crown size, leaf area and synthesis of carbohydrates and hormonal growth regulators (Misra et al. 1996). The total volume of wood under bark ha -1 was found higher at close spacing. This was due to more number of trees per ha -1 (Misra et al. 1996). Our results fully agreed with these findings.

After application of the fertilizers (N:P:K) in March, during early 3 years, significant growth increase was recorded in all the species.

Cromer and William (1982) had reported the effect of age and altitudes on growth of some species of Eucalyptus. In case of Eucalyptus, our results fully agree with these findings. There was no significant difference between the lower and higher doses of fertilizers.

Conclusion:

The observations at 72 MAP, clearly indicate that agroclimatic conditions of Palampur played a very important role in the growth and biomass production of fast growing fuel wood tree species. S. tetrasperma showed extremely poor growth, P. deltoids did not appear as a fastest growth plant species in comparison to other species. It means that it requires more moisture for production of higher biomass. In case of NPK treatment, it has been noticed that most of the test species had their own internal saturation system beyond that limit they did not accumulate any more or respond positively at 72 MAP. Only lower dose of 50:25:25 NPK kg/ha showed significant impact on over all growth and biomass production. Spacing also had no significant effect on biomass production. On the basis of matter content, M. alba was the best fuel wood species, which indicated lowest moisture content. S. tetrasperma and E. hybrid showed the highest moisture content. S. tetrasperma was the poorest species in all respects.

Acknowledgment: The author thanks to Department of Non-conventional Energy Sources, Government of India, New Delhi, and also to Prof. V.S. Rama Das and Dr. M.B. Tamang for their cooperation during the studies.

References

1. Bajrang, S. and P. N. Misra. (1995). Biomass, Energy content and fuel-wood properties of Populus deltoides clones raised in North Indian Plains. Indian J. of Forestry 18 (4), 278-284.

2. Balsberg Påhlsson, A. M. (1990). Mineral nutrients, carbohydrates and phenolic compounds in leaves of beech (Fagus sylvatica L.) in southern Sweden as related to environmental factors. Tree Physiol. 5, 485-495.

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5. Cole, E.C. and M. Newton (1986). Nutrient, moisture and light relations in 5 year old Douglas-fir plantations under variable competition. Can. J. For. Res. 16: 727:732.

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7. Kozlowski, T.T., P.J. Kramer and S.G. Pallardy (1991). The physiological ecology of woody plants. Academic Press, New York, 639 p.

8. Misra, K.K.; P.N. Rai and H.R. Jaiswal, (1996), Effect of spacing and plant density on the growth of Poplar (Populus deltoides Bartr. Ex Marsh), Indian Forester, Vol. No. 122 (1), 65-68.

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Table 1 Effect of Plant spacing on increment in diameter at ground level in 1996 and 1999, diameter at breast height in 1999.

Plant spacing

Increment in diameter at ground level in 1996 over that in 1993 (%)

Increment in diameter at ground level in 1999 over that in 1996 (%)

Increment in diameter at breast height in 1999 over 1996 (%)

1m x 1m

257.9

365.3

207.2

1m x 0.71m

249.2

343.1

181.5

Table 2 Influence of fertilizer NPK doses on increment in plant height 1996 and 1999.

Fertilizer level

Increment in plant height in 1996 over that in 1993 (%)

Increment in plant height in 1999 over that in 1996 (%)

Fresh biomass (kg/plant) in 1999

F1

197.4

523.8

4.6

F2

297.4

512.8

28.5

F3

285.8

543.5

23.5

F4

280.3

579.4

20.1


1 Institute of Himalayan Bioresource Technology (CSIR) Palampur (HP) INDIA
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