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Dry matter content and its distribution in an age series of Eucalyptus camaldulensis (Dehn.) plantations in Sri Lanka
Forest Ecology and Management, 41 ( 1991 ) 137-142
137
Elsevier Science Publishers B.V., A m s t e r d a m
Dry matter content and its distribution in an age series of Eucalyptus camaldulensis ( Dehn. ) plantations in Sri Lanka D.M.S.H.K. Ranasinghe a,~ and G.J. Mayhead b aDepartment of Botany, University of Sri Jayewardenepura, Nugegoda, Sri Lanka bSchool of Agricultural and Forest Sciences, University College of North Wales, Bangor, LL57 2UW, UK (Accepted 28 March 1990)
ABSTRACT Ranasinghe, D.M.S.H.K. and Mayhead, G.J., 1991. Dry matter content and its distribution in an age series of Eucalyptus camaldulensis ( Dehn. ) plantations in Sri Lanka. For. Ecol. Manage., 41 : 137142. Dry matter production was determined for Eucalyptus camaldulensis aged 2-14 years in Puttalam and Moneragala in Sri Lanka. Total dry biomass ranged up to 163 t ha-~ at 14 years at which point the root system accounted for 5% of the total. The root: shoot ratio declined steadily from a maximum at age 2 of 0.145. Mean annual production per hectare peaked between 10 and 12 years on both sites. Mean annual leaf efficiency index was at a maximum of 4.05 at 4 years (top height 9.2 m). Total above-ground dry weight could be accurately predicted from mean breast height diameter.
INTRODUCTION
This paper quantifies the biomass production and its distribution in Eucalyptus camaldulensis (Dehn.) aged 2-14 years in Sri Lanka. The results are reported more fully by Ranasinghe ( 1989 ). MATERIALS AND METHODS
Stands of unthinned E. camaldulensis aged 2, 4, 6, 8, 10, 12 and 14 years planted at 2.5 m X 2.5 m were located in the dry zone ofSri Lanka at Puttalam (8°N, 80°E; 2 m above sea level; rainfall 1100 mm) and Moneragala (6°N, 81 oE; 170 m above sea level; rainfall 1588 mm). Both sites have a dry season from April to August; the mean annual temperature ranges from 27.2 to ~Formerly of U C N W , Bangor, UK.
0378-1127/91/$03.50
© 1991 i
Elsevier Science Publishers B.V.
138
D.M.S.H.K. R A N A S I N G H E A N D G.J. M A Y H E A D
31.0°C. The soils are well-drained sandy loams with pH ranging from 5.0 to 7.0. Top height (mean of the 100 largest diameter trees per hectare) was determined in each stand as a measure of site quality. Each stand was then sampled between February and March 1987 using a randomly located 20 m × 20 m plot. In each plot the diameter at breast height (1.3 m) of all live trees was measured; the trees were then arranged in a series from smallest to largest diameter and split into five equal groups. The heights of five randomly selected trees in each of the five diameter classes were then measured to produce mean height. Mean height and diameter for the entire sample plot was then calculated by taking the mean of these group means. A tree with these mean dimensions was then selected for destructive sampling for each age class on each site; they were felled and their root systems removed; they were measured for total height and height from ground level to the base of the first whorl of completely live branches. Diameter (over bark and under bark) was also measured at breast height, at the base of the stump, at 0.8 m above ground level, at 5 cm below the base of the first whorl of completely live branches and at 2 m intervals up the stem. All branches were then removed from the main stem and separated in the style of Alemdag (1980) into large ( >/2.5 cm in diameter at their base) and small branches ( < 2,5 cm in diameter at their base). All leaf-bearing twigs were removed from the branches and leaves were stripped from the twigs; petioles remained with the leaves. Sample discs, 3-4 cm thick were cut at breast height, at the tip, and from the basal ends of the third and two-thirds sections of the main stem. Roots were divided into large ( >/2.5 cm diameter) and small ( <2.5 cm diameter) roots. Bark was removed from the bole and all small and large branches but was left on all roots. Fresh weights of all these components were recorded. Representative samples of the parts were taken to the laboratory for the determination of oven dry weight over 48 h (leaves and twigs 70 ° C; bark and wood 105 ° C ). Average wood density values excluding bark were determined from samples cut from the sample discs. RESULTS AND DISCUSSION
As expected, stocking of live stems declined with stand age in both study areas: from 1600 stems ha -1 at age 2 years to 1159 and 1175 at age 14 years in Puttalam and Moneragala, respectively. The biomass data are summarised in Table 1. The dry weight of most tree components increased with advancing age. However, the relative rate of biomass accumulation differed among the component parts; boles showed higher values throughout the age series while leaves, large branches, bark and roots increased at a much slower rate as the stand grew older. The root system had virtually ceased increasing in size from Year 10 onwards on both sites; on both sites the root:shoot ratio declined
DRY MATTERCONTENT OF EUCALYPTUS CAMALDULENSIS
139
TABLEI Dry matter production (t ha-1 ) in an age series ofE. camaldulensis plantations. Figures in brackets indicate percent total dry weight (above and below ground ) Tree component
Age (years) 2
Site 1 Puttalam Leaves
Large branches Bole Bark Total above ground Total roots
Root:shoot LEI a Basal area (m 2 h a - i ) Mean height ( m ) Site 2 Moneragala Leaves
Large branches Bole Bark Total above ground Total roots
Root:shoot LEI a Basal area ( m 2 h a -I ) Mean height ( m )
4
6
8
10
12
14
1.62
2.93
2.97
3.65
4.37
4.66
(26)
(10)
(6)
(4)
(4)
(4)
(3)
1.82 (6) 15.84 (56) 1.98 (7) 25.00 (90) 2.80 (10)
4.03 (8) 29.83 (62) 4.36 (9) 44.29 (90) 4.80 (10)
5.80 (7) 57.90 (71) 4.40 (5) 73.68 (91) 7.70 (9)
8.31 (8) 77.80 (70) 7.50 (7) 100.26 (91) 10.40 19)
8.61 (6) 97.78 (74) 8.53 (6) 121.95 (92) 10.55 (8)
9.07 (6) 111.88 (76) 9. t 7 (6) 137.40 (93) 10.78 (7)
0.112 2.40 5.94
0.108 2.70 7.17
0.104 2.78 10.88
(I.103 2.53 14.14
0.086 2.36 19.77
0.078 2.14 24.70
4.0
7.1
8.4
9.0
13.0
13.5
15.0
1.80 (14) -
1.80 (6) -
6.83 (54) 1.30 (10) 10.98 (87) 1.60 (13)
15.80 (54) 4.45 (15) 25.71 (87) 3.65 (13)
2.82 (5) 4.63 (8) 39.05 (65) 7.43 (12) 55.70 (92) 4.71 (8)
4.41 (4) 8.34 (7) 82.57 (70) 12.14 (10) 110.37 (94) 7.28 (6)
5.01 (3) 9.22 (6) 106.47 (72) 14.42 (10) 138.63 (94) 9.11 (6)
5.03 (3) 9.53 (6) 110.98 (73) 14.84 (10) 143.77 (94) 9.24 (6)
5.10 (3) 9.80 (6) 120.28 (74) 15.33 (9) 153.95 (94) 8.95 (5)
0.145 3.49 2.01
0.141 4.05 6.10
0.084 3.57 7.57
0.065 3.33 15.56
0.065 2.94 20.74
0.064 2.53 24.92
0.058 2.28 26.68
4.0
7.5
8.5
10.0
13.5
14.5
16.0
2.74 (44) 0.34 (5) 5.46 (88) 0.73 (12) 0.133 1.91 1.45
~LEI, mean annual leaf efficiency index.
4.94
140
D.M.S.H.K. RANASINGHE AND G.J. MAYHEAD
steadily and significantly* from Year 2; sites were not significantly different in their root: shoot ratio over the rotation. Leaf weight achieved a m a x i m u m from about Year 10 or just later (i.e. at a top height of 15.2-16.5 m ) . Plots in Moneragala produced significantly* higher total biomass per hectare than those of Puttalam in all the age classes studied except Age 4 years. Total above-ground biomass (Y t ha-~ ) was very closely related to mean plot diameter breast height (X cm ): Puttalam
Y= 11.0X-38.4
Re=0.976"**
(1)
Moneragala
Y=ll.9X-42.2
R2=0.972"**
(2)
Using X 2 instead of X actually decreased the R 2 values to 0.933 and 0.935, respectively. Use of mean height and diameter breast height lead to R 2 values of 0.972*** and 0.980"**, respectively. There was no significant difference between Eqs. ( 1 ) and (2) and Eqn. (3) for the combined data of 14 plots is: Y= 11.6X-41.4
R 2 = 0 . 9 7 2 ***
(3)
Using only diameter breast height, Eqn. ( 3 ) is clearly of considerable interest to managers in assessing biomass yield. Auclair and Cabanettes (1980) and Vasudevan and Madan (1986) also found diameter to be the best independent variable in estimating above-ground biomass. In terms of percentage total dry weight the bole increased while the leaf and root percentages decreased with age. However, branch and bark percentages showed an initial increase, which then decreased and remained fairly constant in older ages. No significant differences in percentage dry matter distribution between the two sites were observed. The mean annual leaf efficiency index (the total dry biomass per hectare divided by dry foliage biomass per hectare and age of the crop ) was higher in Moneragala with levels up to 4.05. Following a rise, both sites declined: Puttalam from Year 8 (top height 9.5 m ) , Moneragala from Year 4 (top height 9.2 m ) . This agrees with the observations of Negi and Sharma (1985) who reported a similar effect on a Eucalyptus hybrid in Tamil Nadu. The mean total annual production per hectare (total dry weight per hectare divided by crop age) increased up to 10 years (calculated from curvilinear regression using the two sets of seven sample trees) and thereafter decreased gradually on both sites. The m a x i m u m mean annual production for total above-ground dry weight was calculated as above to occur at age 12 years in Puttalam (seven trees) and age 10 years in Moneragala (seven trees); for bole alone the ages were 12 and 10 years, respectively. Economic restraints or utilisation dimensions may dictate another rotation age. This is in broad agreement with Singh and Sharma ( 1976 ) who reported a possible rotation between 8 and 11 years for Eucalyptus tereticornis in India which is closely related to E. camaldulensis.
141
DRY MATTER CONTENT OF EUCALYPTUS CAMALDULENSIS
TABLE 2 Wood density ( g c m - 3 ) of cross-section discs (minus bark ) in an age series of E. camaldulensis plantations (average of both sites) Density
At breast height At one-third of total height At two-thirds of total height At the tip
Age (years) 2
4
6
8
10
12
14
0.55
0.58
0.60
0.65
0.68
0.70
0.72
0.55
0.53
0.56
0.64
0.67
0.69
0.70
0.54 0.28
0.50 0.35
0.54 0.45
0.62 0.57
0.64 0.60
0.66 0.63
0.68 0.65
The mean tree wood density of cross-section discs increased with increasing age on both sites (Table 2). Mean tree wood density ( g c m - 3) =
Oven dry weight Fresh displaced volume
A density gradient was observed, such that discs taken from towards the top of the tree were of lower density than those towards the bottom. There were no significant differences in wood density between sites. CONCLUSION
Investment in energy plantations requires a careful quantification of yields and growth rates of the species under consideration. The data presented here enable the field forester to predict and understand the timing and form of this yield ofE. camaldulensis in Sri Lanka. ACKNOWLEDGEMENTS
We are grateful for the willing assistance and cooperation of the Government and Forest Department of Sri Lanka, Tom Jenkins and our other colleagues in the School of Agricultural and Forest Sciences, UCNW, Bangor.
REFERENCES Alemdag, I.S., 1980. Manual of data collection and processing for the development of forest biomass relationships. Can. For. Serv. Inf. Rep., P l-X-4 1980, pp. 1-29. Auclair, D. and Cabanettes, A., 1980. Method for the estimation of above-ground biomass on
142
D.M.S.H.K. RANASINGHE AND G.J. MAYHEAD
biomass production in classical coppice and first results. In: W. Palz, P. Chartier and D.O. Hall (Editors), Energy from Biomass, 1st EC Conference held in Brighton, England 4-7 November, Applied Science Publishers, London, pp. 216-221. Negi, J.D.S. and Sharma, D.C., 1985. Biomass and nutrient distribution in an age series of Eucalyptus hybrid plantations in Tamil Nadu. 1. Distribution of organic matter. Indian For., l l l ( 1 2 ) , lll3-1123. Ranasinghe, D.M.S.H.K., 1989. The effect of management influences on biomass production, biomass distribution and the nutrient distribution in fast growing woody species. Ph.D. Thesis, UCNW, Bangor, UK. Unpublished, 416 pp. Singh, R.P. and Sharma, V.K., 1976. Biomass estimation in five different aged plantations of Eucalyptus tereticornis in Western Uttar Pradesh. Oslo Biomass Studies, College of Life Science and Agriculture, University of Maine, Orono, ME. Vasudevan, P. and Madan, M., 1986. Estimating the above-ground dry weight of Ipomeafistula by regression methods. Biomass, 1l: 223-230.
137
Elsevier Science Publishers B.V., A m s t e r d a m
Dry matter content and its distribution in an age series of Eucalyptus camaldulensis ( Dehn. ) plantations in Sri Lanka D.M.S.H.K. Ranasinghe a,~ and G.J. Mayhead b aDepartment of Botany, University of Sri Jayewardenepura, Nugegoda, Sri Lanka bSchool of Agricultural and Forest Sciences, University College of North Wales, Bangor, LL57 2UW, UK (Accepted 28 March 1990)
ABSTRACT Ranasinghe, D.M.S.H.K. and Mayhead, G.J., 1991. Dry matter content and its distribution in an age series of Eucalyptus camaldulensis ( Dehn. ) plantations in Sri Lanka. For. Ecol. Manage., 41 : 137142. Dry matter production was determined for Eucalyptus camaldulensis aged 2-14 years in Puttalam and Moneragala in Sri Lanka. Total dry biomass ranged up to 163 t ha-~ at 14 years at which point the root system accounted for 5% of the total. The root: shoot ratio declined steadily from a maximum at age 2 of 0.145. Mean annual production per hectare peaked between 10 and 12 years on both sites. Mean annual leaf efficiency index was at a maximum of 4.05 at 4 years (top height 9.2 m). Total above-ground dry weight could be accurately predicted from mean breast height diameter.
INTRODUCTION
This paper quantifies the biomass production and its distribution in Eucalyptus camaldulensis (Dehn.) aged 2-14 years in Sri Lanka. The results are reported more fully by Ranasinghe ( 1989 ). MATERIALS AND METHODS
Stands of unthinned E. camaldulensis aged 2, 4, 6, 8, 10, 12 and 14 years planted at 2.5 m X 2.5 m were located in the dry zone ofSri Lanka at Puttalam (8°N, 80°E; 2 m above sea level; rainfall 1100 mm) and Moneragala (6°N, 81 oE; 170 m above sea level; rainfall 1588 mm). Both sites have a dry season from April to August; the mean annual temperature ranges from 27.2 to ~Formerly of U C N W , Bangor, UK.
0378-1127/91/$03.50
© 1991 i
Elsevier Science Publishers B.V.
138
D.M.S.H.K. R A N A S I N G H E A N D G.J. M A Y H E A D
31.0°C. The soils are well-drained sandy loams with pH ranging from 5.0 to 7.0. Top height (mean of the 100 largest diameter trees per hectare) was determined in each stand as a measure of site quality. Each stand was then sampled between February and March 1987 using a randomly located 20 m × 20 m plot. In each plot the diameter at breast height (1.3 m) of all live trees was measured; the trees were then arranged in a series from smallest to largest diameter and split into five equal groups. The heights of five randomly selected trees in each of the five diameter classes were then measured to produce mean height. Mean height and diameter for the entire sample plot was then calculated by taking the mean of these group means. A tree with these mean dimensions was then selected for destructive sampling for each age class on each site; they were felled and their root systems removed; they were measured for total height and height from ground level to the base of the first whorl of completely live branches. Diameter (over bark and under bark) was also measured at breast height, at the base of the stump, at 0.8 m above ground level, at 5 cm below the base of the first whorl of completely live branches and at 2 m intervals up the stem. All branches were then removed from the main stem and separated in the style of Alemdag (1980) into large ( >/2.5 cm in diameter at their base) and small branches ( < 2,5 cm in diameter at their base). All leaf-bearing twigs were removed from the branches and leaves were stripped from the twigs; petioles remained with the leaves. Sample discs, 3-4 cm thick were cut at breast height, at the tip, and from the basal ends of the third and two-thirds sections of the main stem. Roots were divided into large ( >/2.5 cm diameter) and small ( <2.5 cm diameter) roots. Bark was removed from the bole and all small and large branches but was left on all roots. Fresh weights of all these components were recorded. Representative samples of the parts were taken to the laboratory for the determination of oven dry weight over 48 h (leaves and twigs 70 ° C; bark and wood 105 ° C ). Average wood density values excluding bark were determined from samples cut from the sample discs. RESULTS AND DISCUSSION
As expected, stocking of live stems declined with stand age in both study areas: from 1600 stems ha -1 at age 2 years to 1159 and 1175 at age 14 years in Puttalam and Moneragala, respectively. The biomass data are summarised in Table 1. The dry weight of most tree components increased with advancing age. However, the relative rate of biomass accumulation differed among the component parts; boles showed higher values throughout the age series while leaves, large branches, bark and roots increased at a much slower rate as the stand grew older. The root system had virtually ceased increasing in size from Year 10 onwards on both sites; on both sites the root:shoot ratio declined
DRY MATTERCONTENT OF EUCALYPTUS CAMALDULENSIS
139
TABLEI Dry matter production (t ha-1 ) in an age series ofE. camaldulensis plantations. Figures in brackets indicate percent total dry weight (above and below ground ) Tree component
Age (years) 2
Site 1 Puttalam Leaves
Large branches Bole Bark Total above ground Total roots
Root:shoot LEI a Basal area (m 2 h a - i ) Mean height ( m ) Site 2 Moneragala Leaves
Large branches Bole Bark Total above ground Total roots
Root:shoot LEI a Basal area ( m 2 h a -I ) Mean height ( m )
4
6
8
10
12
14
1.62
2.93
2.97
3.65
4.37
4.66
(26)
(10)
(6)
(4)
(4)
(4)
(3)
1.82 (6) 15.84 (56) 1.98 (7) 25.00 (90) 2.80 (10)
4.03 (8) 29.83 (62) 4.36 (9) 44.29 (90) 4.80 (10)
5.80 (7) 57.90 (71) 4.40 (5) 73.68 (91) 7.70 (9)
8.31 (8) 77.80 (70) 7.50 (7) 100.26 (91) 10.40 19)
8.61 (6) 97.78 (74) 8.53 (6) 121.95 (92) 10.55 (8)
9.07 (6) 111.88 (76) 9. t 7 (6) 137.40 (93) 10.78 (7)
0.112 2.40 5.94
0.108 2.70 7.17
0.104 2.78 10.88
(I.103 2.53 14.14
0.086 2.36 19.77
0.078 2.14 24.70
4.0
7.1
8.4
9.0
13.0
13.5
15.0
1.80 (14) -
1.80 (6) -
6.83 (54) 1.30 (10) 10.98 (87) 1.60 (13)
15.80 (54) 4.45 (15) 25.71 (87) 3.65 (13)
2.82 (5) 4.63 (8) 39.05 (65) 7.43 (12) 55.70 (92) 4.71 (8)
4.41 (4) 8.34 (7) 82.57 (70) 12.14 (10) 110.37 (94) 7.28 (6)
5.01 (3) 9.22 (6) 106.47 (72) 14.42 (10) 138.63 (94) 9.11 (6)
5.03 (3) 9.53 (6) 110.98 (73) 14.84 (10) 143.77 (94) 9.24 (6)
5.10 (3) 9.80 (6) 120.28 (74) 15.33 (9) 153.95 (94) 8.95 (5)
0.145 3.49 2.01
0.141 4.05 6.10
0.084 3.57 7.57
0.065 3.33 15.56
0.065 2.94 20.74
0.064 2.53 24.92
0.058 2.28 26.68
4.0
7.5
8.5
10.0
13.5
14.5
16.0
2.74 (44) 0.34 (5) 5.46 (88) 0.73 (12) 0.133 1.91 1.45
~LEI, mean annual leaf efficiency index.
4.94
140
D.M.S.H.K. RANASINGHE AND G.J. MAYHEAD
steadily and significantly* from Year 2; sites were not significantly different in their root: shoot ratio over the rotation. Leaf weight achieved a m a x i m u m from about Year 10 or just later (i.e. at a top height of 15.2-16.5 m ) . Plots in Moneragala produced significantly* higher total biomass per hectare than those of Puttalam in all the age classes studied except Age 4 years. Total above-ground biomass (Y t ha-~ ) was very closely related to mean plot diameter breast height (X cm ): Puttalam
Y= 11.0X-38.4
Re=0.976"**
(1)
Moneragala
Y=ll.9X-42.2
R2=0.972"**
(2)
Using X 2 instead of X actually decreased the R 2 values to 0.933 and 0.935, respectively. Use of mean height and diameter breast height lead to R 2 values of 0.972*** and 0.980"**, respectively. There was no significant difference between Eqs. ( 1 ) and (2) and Eqn. (3) for the combined data of 14 plots is: Y= 11.6X-41.4
R 2 = 0 . 9 7 2 ***
(3)
Using only diameter breast height, Eqn. ( 3 ) is clearly of considerable interest to managers in assessing biomass yield. Auclair and Cabanettes (1980) and Vasudevan and Madan (1986) also found diameter to be the best independent variable in estimating above-ground biomass. In terms of percentage total dry weight the bole increased while the leaf and root percentages decreased with age. However, branch and bark percentages showed an initial increase, which then decreased and remained fairly constant in older ages. No significant differences in percentage dry matter distribution between the two sites were observed. The mean annual leaf efficiency index (the total dry biomass per hectare divided by dry foliage biomass per hectare and age of the crop ) was higher in Moneragala with levels up to 4.05. Following a rise, both sites declined: Puttalam from Year 8 (top height 9.5 m ) , Moneragala from Year 4 (top height 9.2 m ) . This agrees with the observations of Negi and Sharma (1985) who reported a similar effect on a Eucalyptus hybrid in Tamil Nadu. The mean total annual production per hectare (total dry weight per hectare divided by crop age) increased up to 10 years (calculated from curvilinear regression using the two sets of seven sample trees) and thereafter decreased gradually on both sites. The m a x i m u m mean annual production for total above-ground dry weight was calculated as above to occur at age 12 years in Puttalam (seven trees) and age 10 years in Moneragala (seven trees); for bole alone the ages were 12 and 10 years, respectively. Economic restraints or utilisation dimensions may dictate another rotation age. This is in broad agreement with Singh and Sharma ( 1976 ) who reported a possible rotation between 8 and 11 years for Eucalyptus tereticornis in India which is closely related to E. camaldulensis.
141
DRY MATTER CONTENT OF EUCALYPTUS CAMALDULENSIS
TABLE 2 Wood density ( g c m - 3 ) of cross-section discs (minus bark ) in an age series of E. camaldulensis plantations (average of both sites) Density
At breast height At one-third of total height At two-thirds of total height At the tip
Age (years) 2
4
6
8
10
12
14
0.55
0.58
0.60
0.65
0.68
0.70
0.72
0.55
0.53
0.56
0.64
0.67
0.69
0.70
0.54 0.28
0.50 0.35
0.54 0.45
0.62 0.57
0.64 0.60
0.66 0.63
0.68 0.65
The mean tree wood density of cross-section discs increased with increasing age on both sites (Table 2). Mean tree wood density ( g c m - 3) =
Oven dry weight Fresh displaced volume
A density gradient was observed, such that discs taken from towards the top of the tree were of lower density than those towards the bottom. There were no significant differences in wood density between sites. CONCLUSION
Investment in energy plantations requires a careful quantification of yields and growth rates of the species under consideration. The data presented here enable the field forester to predict and understand the timing and form of this yield ofE. camaldulensis in Sri Lanka. ACKNOWLEDGEMENTS
We are grateful for the willing assistance and cooperation of the Government and Forest Department of Sri Lanka, Tom Jenkins and our other colleagues in the School of Agricultural and Forest Sciences, UCNW, Bangor.
REFERENCES Alemdag, I.S., 1980. Manual of data collection and processing for the development of forest biomass relationships. Can. For. Serv. Inf. Rep., P l-X-4 1980, pp. 1-29. Auclair, D. and Cabanettes, A., 1980. Method for the estimation of above-ground biomass on
142
D.M.S.H.K. RANASINGHE AND G.J. MAYHEAD
biomass production in classical coppice and first results. In: W. Palz, P. Chartier and D.O. Hall (Editors), Energy from Biomass, 1st EC Conference held in Brighton, England 4-7 November, Applied Science Publishers, London, pp. 216-221. Negi, J.D.S. and Sharma, D.C., 1985. Biomass and nutrient distribution in an age series of Eucalyptus hybrid plantations in Tamil Nadu. 1. Distribution of organic matter. Indian For., l l l ( 1 2 ) , lll3-1123. Ranasinghe, D.M.S.H.K., 1989. The effect of management influences on biomass production, biomass distribution and the nutrient distribution in fast growing woody species. Ph.D. Thesis, UCNW, Bangor, UK. Unpublished, 416 pp. Singh, R.P. and Sharma, V.K., 1976. Biomass estimation in five different aged plantations of Eucalyptus tereticornis in Western Uttar Pradesh. Oslo Biomass Studies, College of Life Science and Agriculture, University of Maine, Orono, ME. Vasudevan, P. and Madan, M., 1986. Estimating the above-ground dry weight of Ipomeafistula by regression methods. Biomass, 1l: 223-230.