Fuelwood characteristics of indigenous tree species of north-east India

Fuelwood characteristics of indigenous tree species of north-east India

Biomass and Bioenergy 22 (2002) 433 – 437 Fuelwood characteristics of indigenous tree species of north-east India Rupam Kataki, Dolon Konwer ∗ Depart...

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Biomass and Bioenergy 22 (2002) 433 – 437

Fuelwood characteristics of indigenous tree species of north-east India Rupam Kataki, Dolon Konwer ∗ Department of Energy, Tezpur University, Napaam 784 028, Tezpur, India Received 19 February 2001; received in revised form 23 October 2001; accepted 21 January 2002

Abstract Fuelwood characteristics viz. moisture content, ash, silica, carbon, nitrogen, volatile matter, density and calori.c value of 35 indigenous tree species of the age group of 10 –15 years growing in their natural habitat in north-eastern region of India were determined and Fuel Value Index (FVI) of each of them was calculated. From the experimental data and the FVIs, it is found that Acacia nilotica, Acacia auriculiformis, Albizzia lebbeck, Albizzia procera, Pinus kesiya and Elaeognus umbellata possess better fuelwood characteristics and they may be considered for inclusion in energy plantation programme in the region. ? 2002 Published by Elsevier Science Ltd. Keywords: Fuelwood characteristics; Indigenous species; North-east India

1. Introduction Biomass accounts for approximately 14% of total energy used globally and it is the largest energy source for the three-quarters of the world’s population who live in developing countries [1]. With an ever-increasing population in developing countries, it can only be expected that the demand for biomass will also increase. In India, rural households depend to a large extent on locally available biomass resources collected from the forests and nearby sites to meet their domestic energy needs [2]. Among the various forms of biomass, though varies from state to state, .rewood is the most attractive one and occupies a predominant place in the rural energy budget of the country. It has been reported that tree felling for .rewood accounts for the largest ∗

Corresponding author. Fax: +91-03712-67006. E-mail address: [email protected] (D. Konwer).

share of wood use in developing countries causing rapid deforestation [3]. The north-eastern hill region of India is no exception, where people have traditionally been relying on fuelwood as a primary source of energy which, in turn is responsible for rapid deforestation in the region [4]. To avert this situation, it is necessary to establish large-scale energy plantations on unused and degraded lands of the region. However, while selecting the tree species for energy plantation, special attention should be given to the indigenous tree species which are traditionally preferred for fuel by the local people. A major study of .rewood crops also recommended that for energy plantation special attention should be given to the tree species found locally and traditionally preferred for fuel [5]. Because of heavy rainfall in the north-east India, there are large number of indigenous tree and shrub species but there is a conspicuous lack of knowledge of their fuelwood characteristics. Recently, various workers reported fuelwood characteristics of some of

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the indigenous tree species of north-east India [6,7]. The present paper deals with the fuelwood characteristics of 35 indigenous tree species of north-east India which have been used as fuel by local people. 2. Materials and methods 2.1. Study site The sites selected for the present study were the forests of Meghalaya State situated in the north-east India. These forests lie between 25◦ 37N and 25◦ 33N latitude and 91◦ 53E and 91◦ 53E longitude. The entire study sites are hilly and rocky and at an average height of about 5000 ft a.s.l. 2.2. Field sampling The age group of the tree species selected for the present study ranges from 10 to 15 years growing in their natural habitat. The .rst branch of 6 –10 cm diameter outside the bark of each of Acacia auriculiformis A. Cunn. ex Benth., A. nilotica (L) Del., Actephila excelsa Muell. Arg., Adina polycephala Benth., Aesculus assamicus Wall., Albizzia chinensis (Osbeck) Merr., A. lebbeck Benth., A. procera Benth., Alnus nepalensis D. Don., Cassia seamea Linn., Cedrela serrata Royle., E. umbellata Thumb., Grevilia robusta R. Br., Lagerstroemia parvi8ora Roxb., Lantana camara Linn., Litsea polyantha Juss., Melia azedarach Linn., P. kesiya Royle., Pinus wallichiana Wall., Prunus ceredoides D. Don., Quercus delbata Hk. f.&Th., Quercus glauca Thumb., Quercus semicaprifolia Sm., Rhus parvi8ora Hk. f., Salix tetrasperma Roxb., Sapindus laurifolius Vahl., Sapindus mukorossi Geartn., Shorea robusta Gaertn. f., Symplocos crataegioides (Gaertn) Ham., Terminalia arjuna Wright&Arn., Terminalia bellerica Roxb., Terminalia chebula Retz., Terminalia tomentosa (D.C.) W.&A., Toona ciliata Roem. and Viburnum contifolium D. Don. was sampled in triplicate in September 1998. 2.3. Laboratory procedure A disc of 2 cm thickness and 4 cm diameter was taken from each of the freshly cut tree species and

the bark portions were removed. Moisture content was determined by drying the wood in an oven at 80◦ C to constant weight. Density was determined by weight loss of the cut discs under glycerin. Ash content was determined by burning 2 g of ground sample in a mufLe furnace at 575 ± 25◦ C for 15 min as per the TAPPI standard method, T211 om-85 [8]. The ash thus obtained was further digested in 50% HCl (evaporated to dryness thrice) and .ltered through the Whatman No. 42 .lter paper. The same .lter paper was ignited in the muMe furnace at 550◦ C and cooled. The weight of the residue is considered as the silica content. Nitrogen was analysed by macrokjeldahl method [9]. Total organic carbon was determined by the Tyurin’s method using potassium dichromate and sulphuric acid as oxidizing agents and titrated against Mohr’s salt. Fixed carbon content in wood samples was determined according to ASTM Test No. D-271-48 [10]. Volatile matter was calculated on the basis of moisture, .xed carbon and ash content as reported by Jain [11]. The − 40 + 60 mesh oven-dried powdered material was pelleted and burnt in an oxygen bomb calorimeter for the determination of calori.c value on dry weight basis. The samples were adjusted for ash content to calculate the calori.c value on ash-free dry weight basis. Fuel Value Index (FVI) of the fuelwood species was calculated by the modi.ed method reported by Bhatt and Todaria [12], where Calori.c value × Density FVI = : Ash content 3. Results and discussion Various physico-chemical properties and FVIs of the fuelwood species are given in Table 1. The eOect of moisture content on fuelwood quality has been reported by a number of investigators [13– 15]. Moisture content in wood generally decreases its calori.c value. From Table 1, it is seen that the moisture content of the tree species under study varies from 31:39 ± 0:74 to 60:77 ± 1:21%. Among all the species, C. serrata, G. robusta, S. mukorossi, Q. delbata, P. ceresoides and M. azedarach were found to have quite low moisture content, the lowest being in C. serrata (31.39%) whereas L. camara, P. wallichiana, P. kesiya, A. chinensis, A. nilotica and A. excelsa showed much higher percentages of moisture content.

Table 1 Various physico-chemical properties and FVIs of 35 indigenous tree species Species

Calori.c value (kJ kg−1 )

Density

Ash (% oven-dry wt.)

Silica (% oven-dry wt.)

Fixed carbon (% oven-dry wt.)

Nitrogen (% oven-dry wt.)

Total carbon (% oven-dry wt.)

Volatile matter

FVI

On dry wt. basis

On ash-free dry wt. basis

(% oven-dry wt.)

49:30 ± 1:11

20:25 ± 0:77

20:44 ± 0:63

0:85 ± 0:05

0:93 ± 0:10

0:80 ± 0:02

21:12 ± 0:39

0:604 ± 0:003

74:35 ± 0:75

28:65 ± 1:40

1851 ± 2:45

50:05 ± 0:49 50:05 ± 0:94 48:70 ± 0:87 39:73 ± 0:74 51:00 ± 0:76

19:50 ± 0:72 16:27 ± 0:41 18:00 ± 0:69 17:42 ± 0:58 18:49 ± 0:44

19:67 ± 0:88 16:85 ± 0:45 18:43 ± 0:75 17:63 ± 0:65 18:95 ± 0:47

0:90 ± 0:05 0:79 ± 0:01 0:72 ± 0:04 0:70 ± 0:03 0:627 ± 0:10

0:84 ± 0:09 3:47 ± 0:20 2:34 ± 0:18 1:21 ± 0:11 2:43 ± 0:05

0:90 ± 0:02 0:83 ± 0:02 0:44 ± 0:05 0:78 ± 0:08 0:70 ± 0:04

19:19 ± 0:43 26:50 ± 0:79 35:43 ± 0:83 25:23 ± 0:66 21:65 ± 0:74

0:491 ± 0:003 0:645 ± 0:004 0:183 ± 0:007 0:479 ± 0:006 0:481 ± 0:002

61:36 ± 0:67 62:73 ± 0:71 78:54 ± 1:20 62:84 ± 0:78 72:03 ± 0:89

29:92 ± 1:57 23:03 ± 1:32 13:53 ± 0:68 33:83 ± 2:79 24:92 ± 1:17

2089 ± 3:97 370 ± 1:12 554 ± 1:35 1008 ± 2:69 477 ± 1:10

46:29 ± 0:61 50:11 ± 0:77 37:23 ± 1:09 43:69 ± 0:58 31:39 ± 0:74 35:91 ± 1:05 32:33 ± 0:92 38:60 ± 0:76 60:77 ± 1:21 51:27 ± 0:77 36:29 ± 0:69 55:34 ± 1:21 55:09 ± 0:83 36:06 ± 0:79 34:61 ± 0:65 32:44 ± 0:63 38:21 ± 1:10 49:29 ± 0:81 50:15 ± 0:49 46:17 ± 0:67 32:55 ± 0:51 48:31 ± 0:54 38:22 ± 0:81

18:79 ± 0:30 18:67 ± 0:66 15:29 ± 0:39 18:77 ± 0:60 20:11 ± 0:84 21:59 ± 0:82 19:57 ± 0:80 13:50 ± 0:43 18:70 ± 0:57 16:91 ± 0:45 20:71 ± 0:32 19:09 ± 0:51 19:30 ± 0:34 19:34 ± 0:38 19:40 ± 0:41 19:50 ± 0:64 19:10 ± 0:86 17:70 ± 0:64 19:70 ± 0:69 19:25 ± 0:41 20:63 ± 0:34 19:32 ± 0:50 21:16 ± 0:79

19:02 ± 0:35 18:84 ± 0:72 15:44 ± 0:44 19:00 ± 0:70 20:36 ± 0:90 21:91 ± 0:87 19:96 ± 0:86 13:90 ± 0:50 19:23 ± 0:60 17:53 ± 0:49 20:93 ± 0:39 19:23 ± 0:64 19:63 ± 0:42 19:65 ± 0:45 19:89 ± 0:51 19:90 ± 0:70 19:50 ± 0:93 18:44 ± 0:70 20:11 ± 0:75 19:85 ± 0:48 21:04 ± 0:37 19:73 ± 0:57 21:82 ± 0:84

0:856 ± 0:06 0:874 ± 0:04 0:495 ± 0:03 0:707 ± 0:04 0:642 ± 0:03 0:737 ± 0:03 0:739 ± 0:05 0:963 ± 0:02 0:759 ± 0:04 0:776 ± 0:01 0:50 ± 0:01 0:50 ± 0:01 0:49 ± 0:01 0:633 ± 0:02 0:831 ± 0:04 0:740 ± 0:03 0:799 ± 0:05 0:837 ± 0:10 0:715 ± 0:06 0:607 ± 0:01 0:757 ± 0:09 0:925 ± 0:01 0:679 ± 0:07

1:21 ± 0:05 0:91 ± 0:04 0:97 ± 0:07 1:25 ± 0:10 1:23 ± 0:09 1:47 ± 0:10 1:95 ± 0:06 2:90 ± 0:07 2:75 ± 0:09 3:56 ± 0:07 1:07 ± 0:06 0:73 ± 0:03 1:69 ± 0:07 1:61 ± 0:09 2:44 ± 0:12 1:99 ± 0:14 2:04 ± 0:07 4:00 ± 0:10 2:05 ± 0:11 3:01 ± 0:14 1:95 ± 0:12 1:74 ± 0:10 3:04 ± 0:17

0:65 ± 0:03 0:55 ± 0:09 0:65 ± 0:03 0:75 ± 0:02 0:60 ± 0:02 0:70 ± 0:04 0:85 ± 0:03 0:50 ± 0:01 0:60 ± 0:02 0:40 ± 0:07 0:70 ± 0:03 0:35 ± 0:01 0:75 ± 0:01 0:75 ± 0:04 1:25 ± 0:07 0:85 ± 0:07 0:90 ± 0:03 0:60 ± 0:05 0:80 ± 0:05 1:60 ± 0:06 0:65 ± 0:06 0:95 ± 0:09 1:55 ± 0:09

16:35 ± 0:66 16:03 ± 0:80 27:31 ± 0:51 23:19 ± 0:63 28:79 ± 0:57 30:40 ± 0:64 27:35 ± 0:30 18:42 ± 0:41 20:75 ± 0:52 27:61 ± 0:40 25:43 ± 0:46 22:19 ± 0:37 24:45 ± 0:35 29:65 ± 0:48 24:29 ± 0:47 26:33 ± 0:60 28:64 ± 0:62 23:21 ± 0:71 19:54 ± 0:37 26:94 ± 0:51 29:91 ± 0:78 28:52 ± 0:54 25:25 ± 0:71

0:930 ± 0:001 0:338 ± 0:003 0:411 ± 0:004 0:910 ± 0:008 0:217 ± 0:004 0:215 ± 0:003 0:219 ± 0:003 0:338 ± 0:003 0:470 ± 0:005 0:510 ± 0:002 0:279 ± 0:007 0:199 ± 0:005 0:117 ± 0:001 0:199 ± 0:001 0:272 ± 0:001 0:383 ± 0:002 0:347 ± 0:004 0:262 ± 0:004 0:580 ± 0:008 0:591 ± 0:004 0:500 ± 0:007 0:372 ± 0:005 0:457 ± 0:007

69:82 ± 1:13 65:13 ± 0:83 66:45 ± 1:15 64:68 ± 0:49 55:59 ± 0:65 71:16 ± 0:86 69:67 ± 1:19 54:75 ± 0:60 69:09 ± 0:71 51:65 ± 0:66 67:41 ± 0:97 55:71 ± 0:73 60:40 ± 0:78 72:30 ± 1:25 59:19 ± 0:67 69:54 ± 1:06 69:16 ± 0:79 67:76 ± 0:76 69:21 ± 1:03 64:18 ± 0:97 72:73 ± 0:94 69:27 ± 0:85 61:49 ± 0:89

36:15 ± 2:43 32:95 ± 2:03 34:49 ± 1:47 31:87 ± 2:12 38:59 ± 1:44 32:22 ± 1:34 38:37 ± 1:75 40:08 ± 3:07 15:73 ± 0:91 17:56 ± 1:44 37:21 ± 1:34 21:74 ± 0:97 18:77 ± 0:74 32:65 ± 1:29 38:66 ± 1:49 39:24 ± 1:37 31:11 ± 1:22 23:50 ± 1:05 28:26 ± 1:49 23:88 ± 1:07 35:59 ± 1:50 21:08 ± 0:97 33:49 ± 2:05

1329 ± 1:93 1793 ± 3:79 780 ± 3:40 1062 ± 2:49 1050 ± 3:24 1082 ± 3:13 742 ± 1:09 448 ± 1:67 516 ± 1:01 369 ± 1:79 968 ± 2:52 1308 ± 3:19 560 ± 1:11 760 ± 2:14 661 ± 3:11 725 ± 2:03 748 ± 2:79 370 ± 1:15 687 ± 2:10 388 ± 1:20 801 ± 1:55 1027 ± 1:35 473 ± 2:17

44:83 ± 0:49 49:00 ± 0:71 40:52 ± 0:71 50:17 ± 0:63

18:84 ± 0:32 18:00 ± 0:70 20:17 ± 0:26 17:93 ± 0:76

19:21 ± 0:39 18:47 ± 0:78 20:69 ± 0:30 18:44 ± 0:90

0:739 ± 0:01 0:657 ± 0:11 0:755 ± 0:09 0:672 ± 0:04

1:95 ± 0:14 2:57 ± 0:13 2:53 ± 0:09 2:78 ± 0:18

0:75 ± 0:01 0:70 ± 0:04 1:00 ± 0:05 0:95 ± 0:01

16:93 ± 0:46 24:59 ± 0:54 22:67 ± 0:24 28:11 ± 0:28

0:347 ± 0:008 0:371 ± 0:004 0:310 ± 0:008 0:260 ± 0:006

67:47 ± 1:05 59:45 ± 0:45 54:10 ± 0:88 69:21 ± 1:01

36:29 ± 1:83 23:84 ± 1:14 34:28 ± 1:79 18:94 ± 0:85

714 ± 1:66 460 ± 1:15 602 ± 1:87 433 ± 1:14

45:13 ± 0:63 37:40 ± 0:55

19:19 ± 0:55 21:47 ± 0:65

19:85 ± 0:60 21:81 ± 0:71

0:773 ± 0:01 0:725 ± 0:07

3:33 ± 0:09 1:57 ± 0:15

0:70 ± 0:01 0:70 ± 0:08

16:75 ± 0:33 28:70 ± 0:80

0:478 ± 0:004 0:251 ± 0:001

67:14 ± 0:97 69:69 ± 1:12

34:79 ± 2:35 32:33 ± 1:80

445 ± 1:21 991 ± 2:39

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A. auriculiformis A. Cunn. ex Benth. A. nilotica (L) Del. A. excelsa Muell. Arg. A. polycephala Benth. A. assamicus Wall. A. chinensis (Osbeck) Merr. A. lebbeck Benth. A. procera Benth. A. nepalensis D. Don. C. seamea Linn. C. serrata Royle. E. umbellata Thumb. G. robusta R. Br. L. parvi8ora Roxb. L. camara Linn. L. polyantha Juss. M. azedarach Linn. P. kesiya Royle. P. wallichiana Wall. P. ceredoides D. Don. Q. delbata Hk. f.&Th. Q. glauca Thumb. Q. semicaprifolia Sm. R. parvi8ora Hk. f. S. tetrasperma Roxb. S. laurifolius Vahl. S. mukorossi Geartn. S. robusta Gaertn. f. S. crataegioides (Gaertn) Ham. T. arjuna Wright&Arn. T. bellerica Roxb. T. chebula Retz. T. tomentosa (D.C.) W.&A. T. ciliata Roem. V. contifolium D. Don.

Moisture (% wt.)

435

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Ash content in wood is an important parameter directly aOecting the calori.c value. High ash content is considered to be a negative character while evaluating the fuelwood characteristics [16 –18]. The present study reveals that high ash content in R. parvi8ora, A. excelsa, L. polyantha, S. laurifolius, T. ciliata, S. crataegioides makes them less desirable for use as fuelwood. Denser species with low moisture content have always been preferred as fuel because of their high energy content per unit volume and slow burning rates [19,20]. The density varies among the species within 0:495 ± 0:03–0:963 ± 0:02 (Table 1). Silica content above 0.70% are preferred because woods release their heat slowly and retain it for a longer period of time after the .re has died oO [11,21]. Silica content in the wood species were found to vary widely from 0:35 ± 0:01% to 1:60 ± 0:06%. Species like S. laurifolius, S. crataegioides, Q. delbata, T. chebula, T. tomentosa and S. robusta are highly silicious. The formation of pure carbon during the burning process of wood is the result of exothermic chemical reactions [11]. The high carbon content of A. polycephala, E. umbellata and P. ceresoides suggests that besides using these species as fuelwoods, they may also be used for other purposes like charcoal and gun powder production. A comparatively higher level of nitrogen content in fuelwood often results in formation of diOerent oxides of nitrogen during its burning [17]. Nitrogen content of diOerent wood samples ranged from 0:117 ± 0:001 (P. wallichiana) to 0:930 ± 0:001 (A. lebbeck). However, lack of research on pollution-related problems of .rewood burning makes it diPcult to .x the level of nitrogen in fuelwood that would cause appreciable health hazards and environmental pollution. The large amount of volatile matter associated with wood is a result of the high number of functional groups and low number of aromatic structure in wood. It has been reported by various investigators that wood with high amount of volatile matter, resin, wax and lignin content produces more heat during combustion [17,22,23]. The volatile matter in the species under study ranged from 13:53 ± 0:68 to 40:08 ± 3:07. The calori.c value of wood depends upon its genetic character and biochemical composition. The mean calori.c values of the species on oven-dry weight basis were within the range of 13:53 ± 0:43

and 21:59 ± 0:82 kJ g−1 and on ash-free dry weight basis ranged from 13:90±0:50 to 21:91±0:87 kJ g−1 . The calori.c values of most of the species were found to be quite comparable to those reported by various workers with other plant species [6,7,11,12,18,23,24]. The FVI is an important parameter for screening desirable fuelwood species. On the basis of various fuelwood characteristics and FVIs it is concluded that fuelwood species such as A. nilotica, A. auriculiformis, A. lebbeck, A. procera, P. kesiya and E. umbellata possess better fuelwood quality and may be considered for energy plantations in north-east India. Acknowledgements We gratefully acknowledge the Senior Research Fellowship to one of the authors (R.K.) from Council of Scienti.c and Industrial Research (CSIR), New Delhi.

References [1] Scurlock JMO, Hall DO. The contribution of biomass to global energy use. Biomass 1990;21:75–81. [2] Bose RK. Biomass energy resources assessment through rural energy surveys—a common approach. In: WerekoBrobby CY, editor. Commonwealth Science Council Technical Publication Series No. 188. London: Commonwealth Science Council, 1985. p. 85–123. [3] Banerjee S, Das T, Roy J, Chakraborty D. Population growth, energy utilization pattern and environmental degradation: a micro study. Demography India 1992;21(2):281–90. [4] Maikhuri RK. Fuelwood consumption pattern of diOerent tribal communities living in Arunachal Pradesh in north-east India. Bioresource Technology 1991;35:291–6. [5] National Academy of Sciences. Firewood crops, shrubs and tree species for energy production. Report of an ad hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development, Commission on International relations. Washington DC, 1980. p. 31. [6] Kataki R, Konwer D. Fuelwood characteristics of some indigenous woody species of north-east India. Biomass & Bioenergy 2001;20:17–23. [7] Konwer D, Kataki R, Deka D. Fuelwood characteristics of some indigenous tree species of north-east India. Indian Journal of Forestry [in press]. [8] TAPPI Test Methods. Atlanta (USA). Technical Association for Paper and Pulp Industries (TAPPI) Publications: 1992.

R. Kataki, D. Konwer / Biomass and Bioenergy 22 (2002) 433 – 437 [9] Humphries EC. Mineral components and ash analysis. In: Peach K, Tracey MV, editors. Modern methods in plant analysis. Berlin: Springer, 1956. p. 468–501. [10] American Society for Testing and Materials. Standard test methods for volatile matter in wood ASTM D 271-48, Philadelphia, 1979. [11] Jain RK. Fuelwood characteristics of indigenous tree species from Central India. Bioresource Technology 1999;68:305–8. [12] Bhatt BP, Todaria NP. Fuelwood characteristics of some mountain trees and shrubs. Commonwealth Forestry Review 1992;71:183–5. [13] Murphey WK, Cutter BE. Gross heat of combustion of .ve hardwood species of diOering moisture content. Forest Products Journal 1974;24:44–5. [14] Ince PJ. Estimating eOective heating value of wood or bark fuels at various moisture contents. USDA Forest Series General Technology Report, EPL-13, Washington, DC, 1977. [15] Ince PJ. How to estimate recoverable heat energy in wood or bark fuels. USDA Forest Series General Technology Report, FPL-29, Washington, DC, 1977. [16] Khoo KC, Young FO, Peh TB. The silica content of the commercial timbers of Peninsular Malaysia. Malaysian Forester 1982;45:49–54.

437

[17] Wang S, HuOman JB, Rockwood DL. Quantitative evaluation of fuelwood in Florida—a summary report. Economic Botany 1989;36(4):381–8. [18] Goel VL, Behl HM. Fuelwood quality of promising tree species for alkaline soil sites in relation to tree age. Biomass & Bioenergy 1996;10(1):57–61. [19] Abbot P, Lowore J, Kho. C, Werren M. De.ning .rewood quality: a comparison of quantitative and rapid appraisal technique to evaluate .rewood species from a southern African Savana. Biomass & Bioenergy 1997;12(6):429–37. [20] Fuwape JA, Akindele SO. Biomass yield and energy values of some fast growing multipurpose trees in Nigeria. Biomass & Bioenergy 1997;12(2):101–6. [21] Singh B, Khanduja SD. Wood properties of some .rewood shrubs in northern India. Biomass 1984;4:235–8. [22] Groves KW, Chivuya AM. Fuelwood evaluation of four Australian grown tree species. In: Boland DJ, editor. Trees for the tropics: growing Australian multipurpose trees and shrubs in developing countries. ACIAR Monograph, vol. 10, 1989. p. 159 – 69. [23] Jain RK. Fuelwood characteristics of medium tree and shrub species of India. Bioresource Technology 1994;47:81–4. [24] Neenan M, Steinback K. Calori.c values for young sprouts of nine hardwood species. Forest Science 1979;25:445–61.