ANALYSIS
Comparative ecological-economic analysis of growth
performance of exotic
Eucalyptus tereticornis
and indigenous
Dalbergia sissoo
in mono-culture plantations
R.K. Jalota , K.K. Sangha *
Department of Botany,Panjab Uni6ersity,Chandigarh160014,India
Received 7 May 1999; received in revised form 23 December 1999; accepted 4 January 2000
Abstract
This paper describes the comparative growth performance of and monetary returns forEucalyptus tereticornisand
Dalbergia sissooplantations in northern India. The growth is analysed in terms of annual and relative growth rates of bole, crown and marketable heights and volumes, and diameter at breast height. The measurements were taken at 6 – 8 and 19 – 21 years of age. The economic gains are considered for five components, i.e. timber, fuel-wood, fodder, oil and ash. The old plantations ofD.sissooare found to be more sustainable in terms of growth performance and net monetary return. The total monetary gains estimated are Rs. 13.4 million per hectare in the case ofD.sissoo, but only Rs. 7.4 million per hectare forE.tereticornis, even after including the value of all rotational crops possible within the 21-year life span. This integrated analysis challenges the long claimed forest policy that fast growing trees perform better than indigenous trees. © 2000 Elsevier Science B.V. All rights reserved.
Keywords:Eucalyptus tereticornis;Dalbergia sissoo; Mono-culture plantations; Ecological-economic analysis
www.elsevier.com/locate/ecolecon
1. Introduction
In India, when it was realised that there was an increasing demand for wood, and forests
re-sources had been over-used, fast growing exotic tree plantations as wood crops were considered as the best alternative by various governmental and non-governmental agencies. Among the various exotic tree species grown in India (Leucaena leu
-cocephalla, Populus deltoides, Eucalyptus species,
Prosopis juliflora), Eucalyptus tereticornis was largely promoted throughout the country in 1970 – 1980. Quick monetary returns due to short life span, greater number of trees per unit area and less post-plantation care were considered the * Corresponding author. Present address: Plant Sciences
Group, Primary Industries Research Centre, School of Biolog-ical and Enviromental Sciences, Central Queensland, Univer-sity Rockhampton 4702, Qld, Australia.
E-mail addresses: r –jalota@yahoo.com (R.K. Jalota),
sangha –7@yahoo.com (K.K. Sangha)
main reasons for the shift from indigenous to exotic trees.
Later on ecologists and policy makers were divided as to tree performance and the ecological effects of E. tereticornis. Shiva and Bnadyopad-hyay (1987) discussed its negative impact on water resources, soil, air and human skin. In promoting wide-scale cultivation of E. tereticornis only its wood productivity has been emphasised, while other non-wood products and ecological effects have generally been ignored. This has led to inap-propriate assessment of the potential of exotic versus indigenous trees. Indigenous species such asDalbergia sissoo, although having a long gesta-tion period, fetch a better price for their wood, in addition to various intangible products such as fodder and ash which are commonly used by locals.
The claimed fast growth rate and projected returns of E. tereticornis over indigenous trees such as D. sissoo have led us to investigate the ecological and economic potential of both tree species at 6 – 8 years and 19 – 21 years, correspond-ing to the maturation age of the respective trees.
2. Methodology
Two sets of tree plantations (E.tereticornisand
D.sissoo), in triplicate, 6 – 8 and 19 – 21 years old, respectively, were selected in the territory of Chandigarh, North India (30°42%N, 76°54%E, 333
msl), at sites with similar edapho-climatic conditions.
2.1. Measurement of growth parameters
The data were collected on 20 randomly se-lected, duly marked trees at each site from 1995 to 1998. The spatial arrangement of trees is shown in Table 1. The measurements were made in terms of bole, crown and marketable heights using Re-laskop, and diameter at breast height using a measuring tape. The bole, crown and marketable volumes were calculated following Philip (1994):
Bole and marketable volume=pr2h(0.5) and
Crown volume=pd2hf/4
where r is mean tree radius,h is tree height, d is crown diameter, and f is form factor for crown volume (taken as 0.33 for E. tereticornis and 0.5 for D. sissoo).
The growth performance for all the observed parameters was been analysed in terms of annual growth rate (AGR) and relative growth rate (RGR) as follows:
Annual growth rate (AGR)
=Final reading−initial reading
time period in years and
Relative growth rate (RGR)
=logn (final reading)−logn (initial reading)
time period in years
The data were statistically analysed employing Student’s t-test (using Ecostat software) to ob-Table 1
Site details of 6–8- and 19–21-year-old mono-culture plantations
Site E.tereticornis D.sissoo
Spacing of trees Number of trees per hectare Spacing of trees Number of trees per hectare
6–8-Year-old plantations
892 3.3×3.3
1287 i 2.5–3.0×2.5–3.0
2.3–2.8×2.3–2.8 1492
ii 3.4×3.4 842
2.7×2.7 1301 3.2–3.5×3.2–3.5
iii 853
19–21-Year-old plantations
i 2.5×2.5 1579 3.2×3.2 906
2.3×2.3 1605 3.4×3.4 821
ii
2.4×2.4 1594 3.3×3.3 852
serve the level of significant difference for each parameter between the two populations (i.e. tree species), and discriminant analysis (using stato-graphic software) to compare all the parameters of one site of one species with the corresponding site of another species, to obtain an overall con-clusion about tree performance.
2.2. Measurement of economically important parameters
The economic viability of both tree plantations was analysed in terms of five components, i.e. timber, fuel-wood, eucalypt oil, fodder and ash content at the 8th and 21st years of growth.
2.2.1. Timber
The timber volume was calculated from the marketable tree height and mean girth for 20 randomly selected trees following Philip (1994):
Timber volume (m3)
=pr2h(0.00015)
The monetary returns were estimated according to the market price available in the local timber market.
2.2.2. Fuel-wood
The quantity of fuel-wood was measured from previously felled trees in young and old planta-tions at each site. This was necessary as the felling of the trees was prohibited at all sites. The mone-tary value was estimated with respect to market price.
2.2.3. Eucalypt oil
The mean amount of eucalypt oil per unit leaf fresh weight was estimated during spring, sum-mer, autumn and winter, at each of theE. tereti
-cornis sites. The monetary value was calculated according to the price assigned by the Forest Department, Ooty, State of Karnatka, where eu-calypt oil is extracted on a commercial scale (no such industry existed around Chandigarh) in or-der to calculate the entire potential value of E.
tereticornis as a standing crop.
2.2.4. Fodder
The mean amount of fresh leaves (kg/tree) was measured during the different seasons of the year (spring, summer, autumn and winter) for 20 sam-pled trees of D. sissoo in each of young and old plantations. The measurements were based on calculation of the number of leaves per quater-nary branch, per tertiary branch, and then per secondary and primary branches. Accordingly to-tal fresh leaf weight per tree was calculated.
The monetary value of fodder was estimated from the shadow price assigned by locals, as these leaves are browsed by their cattle and goats. Locals, who used to bring their animals into the plantation areas, were asked how much they would have to spend if they did not use D.sissoo
leaves as fodder. As mentioned by Khan (1979) these leaves are highly nutritious for animals. Unfortunately, no direct price was available for this particular usage.
The leaves of E. tereticornis have no value as fodder.
2.2.5. Ash
The ash obtained from simple burning of fuel-wood is largely used by the locals in their house-holds and for enriching their fields. The calculations were done by simply burning the fuel-wood of both types and ages of trees. The content of ash produced per hectare was esti-mated and its monetary value was assigned by the shadow price method, based on the local prefer-ence for spreading ash on fields rather than using artificial fertilizers; the local women also use ash for barter and to clean utensils.
Table 2
Mean annual growth rate (AGR) (m/year) and relative growth rate (RGR) of bole, crown, marketable heights and respective volumes and diameter at breast height, in 6–8- and 19–21-year-old mono-cultures ofE.tereticornisandD.sissooplantationsa Parameters 6–8-year-old plantations 19–21-year-old plantations
E.tereticornis D.sissoo E.tereticornis D.sissoo
0.436c
Bole height 1.060b 0.798c 1.701b
0.140b 0.114b 0.070c 0.168b
Crown height 1.158b 1.348b 0.979c 2.094b
0.229b 0.085c
0.185b 0.194b
0.986c 0.996c
Marketable height 1.996b 1.582b
0.159b 0.062c
0.227b 0.117b
0.031b
Bole volume 0.012c 0.041c 0.099b
0.587b 0.152c
0.467c 0.282b
2.397c
Crown volume 24.21b 4.749c 35.367b
0.158c 0.308b 0.176c 0.356b
0.021c 0.045c
0.030b 0.107b
Marketable volume
0.647b 0.179c 0.291b
0.488c
0.097b 0.043c
0.069c 0.058b
Diameter at breast height
0.247b
0.171c 0.066c 0.079b
aSimple figures represent the values of annual growth rate (AGR) for the respective parameters. Figures in bold represent the respective values in terms of relative growth rate (RGR). Similar superscripts in a row represent the insignificant values atP=0. 05 level, after applying Student’st-test.
The widely accepted 8-year rotation cycle ofE.
tereticornis (Thapliyal, 1986; Rajan, 1987; Niskanen et al., 1993; Saxena, 1994) led us to examine its monetary value from 8 to 21 years of age, the latter being the minimum maturation age of D. sissoo. Foresters generally base their deci-sions upon growth as well as monetary gain for these two tree species over a short period of time. So, comparative analysis has been done in terms of growth performance and total returns in both age groups of each plantation type.
3. Ecological viability of growth performance in
E. tereticornisand D. sissoo plantations
3.1. 6–8-year-old plantations
The annual growth rate (m/year) in terms of bole and marketable height and volume were observed more in E. tereticornis compared with
D.sissoo plantations. However, no significant dif-ference existed between the crown heights of the two tree types. In contrast the crown volume was
over ten times larger in D. sissoo than E. tereti
-cornis. The annual growth rate (m/year) of di-ameter at breast height was 1.4 times greater for
D. sissoo than E. tereticornis(Table 2).
Simple cumulative/annual growth rate models based on the initial biomass production, have usually been considered for growth expression and have therefore reflected better tree height and girth measurements in E.tereticornisthan D.
sissoo (Upadhyaya, 1996; Dutta, 1997; Nadagouda et al., 1997; Nayak and Senapati, 1997). However, growth analysis in terms of rela-tive growth rate, which is a more reliable statisti-cal approach, presents a different scenario. In fact, growth follows the law of compound inter-est and relative growth rate considers the loga-rithmic function of growth and incorporates the increment with respect to time interval (Kramer and Kozlowski, 1979).
3.2. 19–21-year-old plantations
The annual growth rates (m/year) of bole, crown and marketable heights as well as their respective volumes were significantly higher inD.
sissoothanE.tereticornisplantations. The annual growth rate of diameter at breast height was also 1.34 times greater forD.sissoo compared withE.
tereticornis (Table 2).
The better growth performance of D. sissoo
plantations overE. tereticorniswas further statis-tically proven by relative growth rate. The values of bole, crown and marketable heights in terms of relative growth rate were, respectively, 2.4, 2.28 and 1.88 times greater inD.sissoo thanE. tereti
-cornis. Further, the relative growth rates of bole, crown and marketable volumes inD.sissoo plan-tations were 1.85, 2.02 and 1.62 times greater than the respective values measured in E. tereticornis. TheD. sissoo plantations also showed 1.19 times greater relative growth rate in diameter at breast height than E. tereticornis sites (Table 2). The annual growth rate as well as the relative growth rate of all the studied parameters inD.sissoowere much better for the older plantations compared with the younger ones. Shiva (1993) reported bet-ter mean annual increment in case of D. sissoo
compared with E. tereticornis at 11 years of age. The cumulative growth rate revealed that after 10 – 12 years of growth, D. sissoo performs very well. The short-term approach for quick monetary gain and seemingly fast growth has shifted the
scenario in favour of E. tereticornis, however, in the long term D. sissoo seems to be better for sustainable growth performance.
To estimate the overall tree performance, the data of annual growth as well as relative growth rate for various parameters were subjected to discriminant analysis. The values of lambda (Table 3) strongly favoured D. sissoo plantations at 19 – 21 years of growth. On the other hand, at 6 – 8 years of growth,D.sissoowas more favoured in terms of relative growth rate, followed by annual growth rate, compared withE.tereticornis
plantations of similar age (Table 3).
4. Economic viability of E. tereticornisand D. sissoo plantations
4.1. 6–8-year-old plantations
At the 8th year, the mean timber productivity of E. tereticornis plantations was 201.64 m3/ha,
worth Rs. 1 210 432/ha. In contrast, the timber productivity of theD.sissooplantations was 82.76 m3
/ha, but the wood was worthless as it was immature (Table 4). Nadagouda et al. (1997) esti-mated the wood yield for stem and branches as 105 t/ha forE.tereticorniswith a monetary return of Rs. 72 450/ha, compared with D. sissoo with 56.076 t/ha worth Rs. 42 244/ha, at the end of the 5th year of growth. Chatha et al. (1991) reported that the wood productivity of E. tereticornis can
Table 3
Comparison of overall tree performance in terms of all the studied parameters, collectively, in the 6–8- and 19–21-year-old mono-cultures ofE.tereticornisandD.sissooplantations after applying discriminant analysisa
19–21-year-old plantations ofE. 6–8-year-old plantations ofE.
Parameter
tereticornisversusD.sissoo tereticornisversusD.sissoo
Value of Wilks
Annual growth rates of all the 0.1430*** 0.0*
parameters (bole, crown, lambda marketable heights and volumes and diameter at breast height)
Relative growth rates of all the Value of Wilks 0.0689** 0.0* parameters (bole, crown, lambda
marketable heights and volumes and diameter at breast height)
Table 4
The productivity (kg/ha) and values (Rs./ha) of timber, fuel, oil, fodder and ash along with cost of inputs, in mono-cultures of 6–8-and 19–21-year-oldE.tereticornisandD.sissooplantations
Parameter 6–8-year-old plantations 19–21-year-old plantations
E.tereticornis D.sissoo E.tereticornis D.sissoo
82.76
Timber productivity (m3/ha) 201.64 792.80 538.01
Monetary value (Rs./ha) 1 210 432 – 4 758 980 11 528 440
Fuel-wood productivity (Q/ha) 2642 3676 6855 13 833
477 880 479 850
184 940 798 290
Monetary value (Rs./ha)
10 422 –
Fodder productivity (kg/ha) – 15 137
31 266 –
– 45 412
Monetary value (Rs./ha)
19.75
Eucalypt oil (kg/ha) – 53.38 –
– 2028.44
750 –
Monetary value (Rs./ha)
21 136
Ash content (kg/ha) 44 112 55 213 165 996
44 112
Monetary value (Rs./ha) 21 136 55 213 165 996
553 258 5 296 071
1 417 258 13 538 138
Total monetary value (Rs./ha)
67 371 83 848 71 192
Total expected cost of cultivation including post plantation 83 566 care (Rs./ha)
10 216 11 205
Total expected cost of logging, felling and transportation 13 210 15 729 (Rs./ha)
1 339 671
Net returns (Rs./ha) 458 205 5 211 669 13 438 843
yield Rs. 10 000/ha per annum. Similarly, in other studies only the value of the wood components was assessed, and over a too short period, as most indigenous trees do not mature until 10 – 12 years of age. Thus when comparing the potential of exotic versus indigenous tree species, the total gains to maturity should be taken into consideration.
Moreover, mean productivity as well as the value of non-timber products, i.e. fuel-wood and ash, was greater forD. sissoothan E. tereticornis
plantations. The net return from the commercially exploited product, eucalypt oil, was calculated as Rs. 750/ha. In contrast, the local use ofD.sissoo
leaves as fodder has a potential value of Rs. 31 266/ha (Table 4). The contribution of such non-timber forest products to the local economy was estimated to be approximately a million ru-pees in Madumalai, India by Ganesan (1993).
The net returns forE.tereticorniswere assessed to be Rs. 1 339 671/ha, i.e. 2.92 times greater than for D. sissoo (458 205 Rs./ha). A possible reason for the low value ofD.sissooplantations is its nil timber value at this age, but once the tree reaches 8 – 10 years of age, its timber begins to fetch very high prices. Secondly, the omission of non-timber
products, which are used by the locals and also provide various ecological services, appears re-sponsible for the low visible monetary returns in
D.sissoocompared withE.tereticornis, at the 8th year of growth.
4.2. 19–21-year-old plantations
The monetary potential of E. tereticornis and
D. sissooplantations showed an entirely opposite scenario at the 21st year of growth. Though tim-ber productivity was estimated to be 1.47 times better in E.tereticornis plantations, the monetary value was 2.42 times greater in D. sissoo planta-tions, because the market price for D. sissoo tim-ber was over three times that of E. tereticornis. The fuel-wood productivity and its returns in D.
sissoo plantations were over twice those of E.
tereticornis. The potential value of leaves as fod-der was calculated as Rs. 45 412/ha in D. sissoo
The total potential gains, as a standing crop, for the five components were twice as great for
D. sissoo compared with E. tereticornis. The D.
sissoo plantations also showed a net return 2.58 times greater than that of E. tereticornis.
However, within 6 – 8- and 19 – 21-year-old plantations of each species, an increase of net returns of 3.89 times for E. tereticornis and 29.33 times for D. sissoo was seen with the age of respective tree plantations. The old planta-tions of E. tereticornis as compared with younger ones seemed to perform reasonably well for the total visible gains. Campbell and Smith (1987), in a note to the World Bank, advised ‘as
E. tereticornis has been grown in mono-culture plantations with very short rotation cycles in In-dia and thus may cause loss of nutrients, farm-ers should increase the length of rotations’. But the visible gains of E. tereticornis in the short term attracted the farmers and land owners.
When evaluating the total monetary output, an argument is advanced that the income from the first crop of 8-year-old E. tereticornis, if sub-jected to fixed deposit rates at a widely accepted 10% interest rate, can shift the situation in fa-vour of E. tereticornis. In that case, after cutting the first crop, the coppice plant will grow again to provide the second crop. Keeping this in mind and assuming the same input and output charges (which is not practically feasible, and there are usually less gains in a second crop), an attempt was made to calculate the net returns over the 21-year life span. The 21 years, in fact, represent the minimum maturation age of D.
sissoo: within the same period, two and half crops at a rotation of 8 years can be expected for E. tereticornis. Thereby, the net returns of an 8-year-old E. tereticornis plantation (first crop), for all the considered products, are sub-jected to 10% compound interest rate for 13 years, and seem almost three times better than that of D. sissoo plantations of a similar age (Table 5). The second crop of E. tereticornis
supported a value of Rs. 2 157 553/ha, after in-cluding interest for 5 years, and a third crop was expected to provide Rs. 669 835/ha for its 5 years’ growth. However, no such rotation of crops occurs in the case of D. sissoo. It is sig-nificant to mention here that in this analysis, the net returns for marketable as well as non-mar-ketable products have been considered because assigning monetary value to any good/service is a man-made parameter which depends upon its availability (Nautiyal, 1988): a monetary value for fodder and ash is thus incorporated into the potential use of these ecological services.
As is clear from Table 5, the net returns over 21 years, even after including the interest for each crop, in case of E. tereticornis, were calcu-lated as Rs. 7.4 million per hectare. This amount was nearly 1.8 times less than the total direct gains obtained from D. sissoo plantations at 21 years of age. On the other hand, the com-parison of direct returns arrived after cutting the plantation in the 21st year of growth, showed 2.57 times better benefits in case of D. sissoo
than E. tereticornis plantations. Table 5
The amount of total returns (Rs./ha) inE.tereticornisfor the 21 years of life span, at rotation cycle of 8 years, and inD. sissoo, arrived indirectly after including interest for each cop-pice crop and directly after cutting the crop at the 21st year of age
E.tereticornis D.sissoo Amount (Rs./ha) at
different time intervals
458 205 Returns from the first 1 339 671
crop (Rs./ha)
Amount after 13 years at 4 621 865 1 580 807 10% compound interest
rate
Returns from the second 1 339 671 – crop (Rs./ha) (assumed
the same as for first crop)
After 5 years at 10% 2 157 553 – interest rate
Returns for the third crop, 669 835 – after 5 years of growth
(assumed to be half than first/second crop)
7 449 253 –
Total returns in 21 years
5 211 669
Direct returns from a tree 13 438 843 plantation at 21st year
5. Conclusion
The plausible argument of greater monetary gain withE.tereticornisdoes not seem valid in the long term. The growth performance of both tree species showed a small difference in the 6 – 8-year-old plantation. However, a big gap was evident in the 19 – 21-year-old plantations, in favour of D.
sissoo. The E. tereticornis performs well in early phase due to vast extraction of water and nutri-ents, with hardly any returns to the soil (Poore and Fries, 1985; Shiva and Bnadyopadhyay, 1987; Mongia et al., 1997; Jaiyeoba, 1998; Jama et al., 1998). Chaturvedi and Behl (1996) claimed ‘The species that grow faster in the early stage did not perform well in the later years’. On the other hand, better performance ofD.sissoo in terms of tree productivity (Qureshi, 1967; Geetha et al., 1994; Jalota, 1997), understorey vegetation (Singh, 1991; Jalota and Kohli, 1996; Kohli et al., 1998) and soil nutrient status (Toky, 1992; Singh and Jha, 1993; Gera et al., 1996) has been ob-served. But, few reports on evaluation of ecologi-cal parameters together with their monetary assessments are available.
In the present study, the integrated ecological-economic accounting reveals that the ecological performance as well as monetary gains are much better at 21 years of age for D. sissoo compared with E. tereticornis. The returns from non-timber products were estimated to be greater for D.
sissooplantations thanE.tereticornis, irrespective of age. Usually, these non-timber forest products have been ignored during assessment of the mone-tary potential of a tree plantation. This was one of the prime reasons why Eucalyptus cultivation was promoted at the cost of indigenous tree spe-cies. McKenny and Sarker (1994) assessed the monetary value of non-wood products and ser-vices in the forests of Ontario and considered that these represent ecological sustainability. The po-tential use value of fodder and ash together with other ecological services, if examined when assess-ing the benefits ofD.sissoo orEucalyptusspecies, would have certainly resulted in a policy change. While keeping in view the sustainability aspect, the D. sissoo plantations seem to be better in ecological as well as economic terms. The old
plantations of D. sissoo provide a continuum of various ecological services, supporting its quite high value. On the other hand, E. tereticornis
provides a discontinuous services due to its rota-tion period, and has adverse ecological effects. Thus, an inappropriate assessment can be seen to adversely affect the whole system as is apparent in the plains of northern India where most indige-nous tree species have been replaced with exotic ones, particularly Eucalyptus.
Therefore, before the implementation of any policy, foresters, environments, farmers and pol-icy makers should discuss and evaluate the real tree potential. An attempt should be made to estimate the value of various services used at local level. For such an approach, integrated ecologi-cal-economic accounting seems to be most suit-able for correct value judgements.
Acknowledgements
Financial assistance from CSIR (Council of Scientific and Industrial Research) and UGC (University Grants Commission) is gratefully ac-knowledged. We are also thankful to Dr Amar-nath Gill, Department of Statistics, Panjab University, Chandigarh, for his great help with statistical analysis of the data. The constructive suggestions of Dr B.O. Danielsson and Dr R. Costanza on an earlier draft helped us to improve this manuscript.
References
Campbell, J., Smith, D.M., 1987. The Effects of Short Rota-tion Mono-Cultures ofEucalyptuson Rural Ecosystems of India with Particular Reference toEucalyptus tereticornis Plantations in Social Forestry. World Bank, Washington, DC Report to the World Bank, 6 March, 78 pp. Chatha, I.S., Singh, J., Sidhu, D.S., 1991. An Economic
Analysis of EucalyptusPlantations in Punjab. Paper pre-sented at the workshop on socio-economic aspects of tree growing by farmers in South India, held at the Institute of Rural Management, Anand, 11 – 15 March, pp. 22 – 34. Chaturvedi, A.N., Behl, H.M., 1996. Biomass production
tri-als on sodic site. Indian Forester 122 (6), 439 – 455. Dutta, M., 1997. Growth performance and biomass
Ganesan, B., 1993. Extraction of non-timber forest products, including fodder and fuel-wood in Mudumalai, India. Econ. Bot. 47 (3), 268 – 274.
Geetha, G., Gopikumar, K., Arvindakshan, M., 1994. Com-parative growth of multipurpose (indigenous vs exotic) tree species in the warm humid tropics of Kerala. Indian J. For. 17 (2), 134 – 136.
Gera, M., Ginwal, H.S., Srivasta, R.L., 1996. Performance of 17 different multipurpose tree species under semi-arid re-gion of central Asia. Indian Forester 122 (3), 250 – 257. Jaiyeoba, I.A., 1998. Changes in soil properties related to
conservation of savannah woodland into pine andEuca -lyptusplantations, northern India. Land Degradation Dev. 9 (3), 207 – 215.
Jalota, R.K., 1997. Comparison of ecophysiological functions of mono-culture plantations of exotic (EucalyptusL’Herit) to indigenous tree species and forest ecosystems in semi-arid zone. Ph.D. thesis, Panjab University, Chandigarh, India.
Jalota, R.K., Kohli, R.K., 1996. Status of floor vegetation under exotic and indigenous tree plantations in semi-arid zone of north India. In: Kohli, R.K., Arya, K.S. (Eds.), Resources Inventory Techniques to Support Agroforestry and Environment. Proceedings of the IUFRO-DNAES International Meeting, 1 – 3 October 1996, at Chandigarh, India, pp. 291 – 296.
Jama, B., Buresh, R.J., Ndufa, J.K., Shepherd, K.D., 1998. Vertical distribution of roots and soil nitrate: tree species and phosphorus effects. Soil Sci. Soc. Am. J. 62 (1), 280 – 286.
Khan, A.A., 1979. A note on the nutritive value of forages for nilgai. Pak. J. For. 29 (3), 199 – 202.
Kohli, R.K., Sangha, K.K., Jalota, R.K., Ghuman, B.S., 1998. Economic evaluation of wood and phytodiversity on the floor of indigenousDalbergia sissooand exoticEucalyptus tereticornis. In: Yoshimoto, A., Yukutake, K. (Eds.), Global Concerns for Forest Resource Utilization — Sus-tainable Use and Management. Proceedings of an Interna-tional Symposium, 5 – 8 October, 1998, at Miyazaki, Japan, pp. 558 – 565.
Kramer, J., Kozlowski, T.T. (Eds.), 1979. Physiology of Woody Plants. Academic Press, New York 811 pp. McKenny, D., Sarker, R., 1994. An overview of non-wood
valuation of forests in Ontario. Forest Chronicle 70 (1), 47 – 54.
Mongia, A.D., Dey, P., Singh, G., 1997. Impact of soil sodic-ity on performance of some tree species: a case study of spatial variability. J. Indian Soc. Soil Sci. 45 (4), 810 – 812.
Nadagouda, V.B., Patil, C.V., Desai, B.K., Manjappa, K., 1997. Growth and yield of seven tree species under high density planting and irrigation. Indian Forester 123 (1), 61 – 65.
Nautiyal, J.C., 1988. Forest Economics — Principles and Applications. Natraj, Dehradun 580 pp.
Nayak, P.K., Senapati, S.C., 1997. Evaluation of tree species under silvicultural system. Environ. Ecol. 15 (4), 874 – 876. Niskanen, A., Luukkanen, O., Saatamoinen, O., Bhumibha-mon, O., 1993. Evaluation of profitability of fast growing tropical trees: Eucalyptus camaldulensis, Acacia mangium andMelia azedarachas plantation tree crops in Thailand. Acta Forestalia Fennica 241.
Philip, M.S., 1994. Measuring Trees and Forests. CAB Inter-national 310 pp.
Poore, M.E.D., Fries, C., 1985. The Ecological Effects Of Eucalyptus. Food and Agriculture Organisation, United Nations, New York FAO Forestry Paper 59.
Qureshi, I.M., 1967. The concept of fast growth in forestry and place of indigenous fast growing broad leafed species. In: Proceedings of the Eleventh Silvicultural Conference, vol. 2. Forest Research Institute and Colleges, Dehradun, India, p. 505.
Rajan, B.K.C., 1987. Versatile Eucalyptus. Diana, Benglalore 243 pp.
Saxena, N.C., 1994. India’s Eucalyptus Craze — The God That Failed. Sage, New Delhi 264 pp.
Shiva, V., 1993. Monocultures of The Mind — Biodiversity, Biotechnology and the Third World. Third World Net-work, Penang, Malaysia 184 pp.
Shiva, V., Bnadyopadhyay, J., 1987. Ecological Audit of Euca-lyptus Cultivation. Research Foundation for Science, Technology and Ecology, Dehradun 74 pp.
Singh, D., 1991. Phytotoxic properties of Eucalyptus with special reference to the role of its volatile components. Ph.D. thesis, Panjab University, Chandigarh, India. Singh, K., Jha, M.N., 1993. Trees, shrubs and grasses on
saline soils of Indo-Gangetic Plains. Indian Forester 119 (8), 630 – 647.
Thapliyal, G.B., 1986. Performance of Eucalyptus plantations in the state of West Bengal with special reference to the laterite tract. In: Sharma, T.K., Nair, T.S., Kedarnath, S., Konda, S. (Eds.),Eucalyptusin India — Past, Present and Future. Kerala Forest Research Institute, Peech 184 pp. Toky, O.P., 1992. Revegetating Deforested Problem Sites.
Reforestation of Degraded Land: Concepts and Strategies. Rastogi, Meerut, India.
Upadhyaya, A.K., 1996. Tree growth and forage production in block and canal side plantations of I. G. N. P. stage-II. Indian Forester 122 (2), 117 – 121.
