Fuelwood characteristics of tree species in homegardens of Kerala, India

Indiscriminate use of natural resources in the past has lead to fuelwood shortages in many parts of the tropical world. To surmount this domestic energy crisis, not only degraded sites must be planted with trees having high fuel value potential, but also agroforestry promoted on arable lands. To enable choice of species for such energy plantations/agroforests in the humid tropics of peninsular India, we assessed the heat of combustion and physical properties that determine combustion of phytofuels, such as ash content, specific gravity and moisture content. Bark and wood samples of 45 multipurpose tree species in the homegardens of Kerala, India and three fuel materials of local importance (coconut [Cocos nucifera] endocarp, dried coconut spathe and dehiscent rubber [Hevea braziliensis] pericarp) were evaluated. Variations abound in the calorific values and physical properties of species and tissue-types. In general, heat of combustion and specific gravity followed the sequence: heartwood > sapwood > bark, while mean ash percentage followed a reverse order (bark > sapwood > heartwood). Ash content had a negative correlation with heat of combustion, but specific gravity exerted a positive influence. Furthermore, ash content and wood specific gravity were inversely related. Although green moisture content increased in the order: bark < heartwood < sapwood, it failed to show any predictable relationship with heat of combustion.This revised version was published online in November 2005 with corrections to the Cover Date.     

Soil Properties Affecting the Frost Sensitivity of Beech Bark in Southern Sweden

Decline in pH and leakage of base cations have been recorded in beech forest soils in southern Sweden. This study investigated the influence of soil properties on frost sensitivity in beech bark and evaluated the effects on frost sensitivity of soil treatment with lime, wood ash or excessive N fertilization. Beech trees on five experimental sites were studied. The results indicated that beech trees subjected to a comparatively low C/N ratio and low concentration of nutrient elements in the mineral soil layer were predisposed to a higher sensitivity to frost. Seven years after treatment, no effects of N fertilization were detectable in the soil, but positive effects of liming were recorded. There were no obvious effects of bark ash amendments, owing to large differences among blocks at the site.     

Composition of inorganic elements and the leaching behavior of biomass combustion ashes discharged from wood pellet boilers in Japan

To evaluate the characteristics of wood ash as fertilizer, composition of inorganic elements and the leaching behavior were studied. The leaching behavior was evaluated by three leaching methods using different solvents (water, hydrochloric acid, and acetic acid: Japanese leaching test Nos. 18 and 19 and modified toxicity characteristic leaching procedure prescribed by the US Environmental Protection Agency). The ash composition varied according to raw materials for fuel and ash collection systems. Concentration of Na, Al, Si, and V became higher in bark ashes while that of K became higher in wood ashes. Pb, Cd, Se, and Zn were more volatile and enriched in fly ashes. Of the nutrient elements, K showed high water solubility and its phytoavailability also appeared high, although the amount of water-soluble K was low in bark ash. Ca and Mg had intermediate solubility while P was less soluble in both water and acetic acid. The amount of hazardous substances having leached was low for most, but not all the ashes, in terms of Pb, Cr and As. Nevertheless, the phytoavailability of these hazardous substances after their application to the forest appeared low, due to their amphoteric leaching behavior and the acidity of Japanese forest soils.     

Impact of silviculture on dead wood and on the distribution and frequency of tree microhabitats in montane beech-fir forests of the Pyrenees

In forest ecosystems, the level of biodiversity is strongly linked to dead wood and tree microhabitats. To evaluate the influence of current forest management on the availability of dead wood and on the abundance and distribution of microhabitats, we studied the volume and diversity of dead wood objects and the distribution and frequency of cavities, dendrothelms, cracks, bark losses and sporophores of saproxylic fungi in montane beech-fir stands. We compared stands unmanaged for 50 or 100 years with continuously managed stands. A total of 1,204 live trees and 460 dead wood objects were observed. Total dead wood volume, snag volume and microhabitat diversity were lower in the managed stands, but the total number of microhabitats per ha was not significantly different between managed and unmanaged stands. Cavities were always the most frequent microhabitat and cracks the least frequent. Dendrothelm and bark loss were favored by management. Beech (Fagus sylvatica) carried many more microhabitats than silver fir (Abies alba), especially cavities, dendrothelms and bark losses. Fir very scarcely formed dendrothelms. Secondary tree species played an important role by providing cracks and bark losses. The proportion of microhabitat-bearing trees increased dramatically above circumference thresholds of 225 cm for beech and 215 cm for fir. Firs with a circumference of less than 135 cm did not carry microhabitats. In order to conserve microhabitat-providing trees and to increase the volume of dead wood in managed stands, we recommend conserving trees that finish their natural cycle over 10–20% of the surface area.     

Charcoal and fuel value of agroforestry tree crops

Charcoal was produced from short rotation tropical species ofLeucaena leucocephala andTectona grandis. The combustion-related properties, moisture content, specific gravity and percentage element composition of carbon, hydrogen, oxygen, nitrogen, sulphur and ash in wood and charcoal from the two species were determined. The gross heat of combustion of wood and charcoal was also determined.There were significant differences in the moisture content, specific gravity and percentage element composition between wood and charcoal from the two species. The carbon and ash content of charcoal were higher than those of wood. The average heat of combustion of charcoal 25.25 MJKg^–1 was higher than that of wood 13.75 MJKg^–1.     

Wood characteristics of Podocarpus oleifolius var. macrostachyus (Parl.) Buchholz and Gray native to Costa Rica: their significance for wood utilization

Due to over-exploitation in the past, native conifer species in many tropical countries are hardly available anymore for wood utilization. In the last decades Costa Rica has undertaken considerable efforts to study the silvicultural characteristics of the native species of the family Podocarpaceae, in particular Podocarpus oleifolius var. macrostachyus (Parl.) Buchholz and Gray, in order to evaluate its suitability for cultivation in mixed plantations with preference for native species. However, sufficient information on the structural, chemical and physical characteristics of the wood of this species are not available. This investigation reports on selected wood characteristics of old-growth trees from the Cordillera de Talamanca (approximately 2,700 m a.s.l.), Costa Rica. Tracheids occupy 93% of total volume; average tracheid length is 4 mm, wall thickness ranges 2.5–4.5 (–6.5) μm throughout the annual increment. Lignin content is between 33.6 and 34.7% excluding any lignin-like compounds. Cellular UV microspectrophotometry reveals that the compound middle lamella (CML) and S2 layer are characterized by a higher absorbance than is commonly observed in e.g. Pinaceae, and with a distinct gradient from S1 to S3. The carbohydrate (cellulose and hemicelluloses) composition reflects the typical proportions as found in other conifers. A low content of organic extractives explains the only moderate (white rot) to low (brown rot) natural durability of the heartwood against wood destroying fungi. The wood density (12% mc) ranges 0.5–0.68 g cm^-3; compression strength (44±2.38 MPa) and corresponding modulus of elasticity (8,600±1,720 MPa) indicate good elastomechanical properties. Accordingly, the wood is recommended for multiple indoor enduses. For exterior applications, effective protective measures and/or preservative treatment are required. Dedicated to Prof. Dr. Dr. h.c. mult. Walter Liese on the occasion of his 80th birthday     

Determinants of litter accumulation and the abundance of litter-associated microarthropods in bird's nest ferns (Asplenium nidus complex) in the forest of Yambaru on Okinawa Island, southern Japan

We studied the distributional pattern of bird's nest ferns (Asplenium nidus complex) and the factors that determined litter accumulation and the abundance of litter-associated microarthropods in the ferns in the forest of Yambaru on the northern part of Okinawa Island, southern Japan. We located 53 bird's nest ferns (41 ferns on 27 live trees of 13 species, and 12 on 5 dead trees) in a ca. 4-ha plot, collected litter samples from 37 ferns on 25 live trees, and then extracted a total of 11 205 microarthropods (Acari and Collembola) from all the litter samples. The ferns preferred concave slopes and tended to be distributed on the tree species that had the typical characteristics of high population density and/or large basal area in the forest. The ferns were usually established on large trees [≥10 m high or ≥20 cm diameter at breast height (DBH)], although the number and size of the ferns were not related to the size of the host trees. The amount of litter accumulated in the ferns was correlated neither with the size (height and DBH) of the host tree nor with the height and position of the ferns. The amount of accumulated litter had a significant positive correlation only with fern size; this might have caused the positive correlations between fern size and the abundance of litter-associated microarthropods and the number of species of oribatid mites in the ferns.     

Variation in density and moisture content of wood and bark among twenty Eucalyptus grandis progenies

Summary Variation in density and moisture content of Eucalyptus grandis wood and bark is described utilizing the trees established for a half-sib progeny test in southern Florida. Differences in density and moisture content among progenies were significant. Variations in wood properties were largely due to the genetic differences. No relationship was found between wood density and wood moisture content. Implications for genetic manipulation of wood quality for this species were discussed.     

Radial variations of wood properties in <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> growing in Bangladesh

Radial variations of wood properties (basic density, fiber length, vessel element length, and compression strength) in plantation-grown Casuarina equisetifolia in Bangladesh were investigated for effective utilization of the wood. Samples disks at breast height were randomly collected from trees in a 10-year-old plantation in Cox’s Bazar Forest Division, Bangladesh. The basic density showed a near-constant value up to 30 mm from the pith and then rapidly increased up to 60 mm from the pith. The fiber length and vessel element length gradually increased from the pith to bark. When radial variation of wood properties was determined according to relative distance from the pith, similar radial patterns were observed among the sample trees, indicating that the wood properties in C. equisetifolia may be related to the growth rate. The compression strength parallel to the grain (CS) increased from the pith to bark. A significant positive correlation was found between the air-dried density and the CS. The results obtained indicated that wood around the pith has a relatively low density, and wood outside the pith area has a relatively high density, suggesting that it could be used as structural lumber. Part of this report was presented at the 58th Annual Meeting of Japan Wood Research Society, Tsukuba, March 2008     

Evaluation of fuelwood quality of indigenous and exotic tree species of India's semiarid region

The fuelwood potential of indigenous (Acacia nilotica, Azadirachta indica, Casuarina equisetifolia, Dalbergia sissoo, Prosopis cineraria andZizyphus mauritiana) and exotics (Acacia auriculiformis, A. tortilis, Eucalyptus camaldulensis andE. tereticornis) trees were studied. Calorific value variations for components, such as, stump, main stem, treetop, branches, foliage and bark, were determined. Tree components differed highly significantly (P<0.01) among groups (indigenous and exotics) and within species. The calorific means ranged from 18.7 to 20.8 MJ/kg for indigenous tree species and 17.3 to 19.3 MJ/kg for exotics. Besides calorific values, other fuelwood characteristics, such as, density, ash, biomass/ash ratio, moisture and nitrogen content were also studied. It was observed that indigenous tree species are better suited as fuelwood species as they contain high density wood, low ash content and low N percentage. The fuelwood value index (FVI) was found to be high of indigenous tree species and was maximum forCasuarina equisetifolia (2815). The most promising tree species were in the order ofC. equisetifolia, A. nilotica andZ. mauritiana.     

Beech decline in Central Europe driven by the interaction between Phytophthora infections and climatic extremes

During the past decade, and in particular after the wet year 2002 and the dry year 2003, an increasing number of trees and stands of European beech (Fagus sylvatica L.) in Bavaria were showing symptoms typical for Phytophthora diseases: increased transparency and crown dieback, small‐sized and often yellowish foliage, root and collar rot and aerial bleeding cankers up to stem heights of >20 m. Between 2003 and 2007 134 mature beech stands on a broad range of geological substrates were surveyed, and collar rot and aerial bleeding cankers were found in 116 (86.6%) stands. In most stands the majority of beech trees were declining and scattered or clustered mortality occurred. Bark and soil samples were taken from 314 trees in 112 stands, and 11 Phytophthora species were recovered from 253 trees (80.6%) in 104 stands (92.9%). The most frequent species were P. citricola, P. cambivora and P. cactorum. Primary Phytophthora lesions were soon infected by a series of secondary bark pathogens, including Nectria coccinea, and wood decay fungi. In addition, infected trees were often attacked by several bark and wood boring insects leading to rapid mortality. Bark necroses were examined for their probable age in order to determine whether the onset of the current Phytophthora epidemic was correlated to rainfall rates recorded at 22 Bavarian forest ecosystem monitoring stations. A small‐scale survey in nine Bavarian nurseries demonstrated regular infestations of all beech fields with the same range of Phytophthora species. The results indicate that (1) Phytophthora species are regularly associated with beech decline and may also be involved in the complex of ‘Beech Bark Disease’, (2) excessive rainfalls and droughts are triggering the disease, and (3) widespread Phytophthora infestations of nursery stock might endanger current and future silvicultural projects aiming on the replacement of non‐natural conifer stands by beech dominated mixed stands.     

Net calorific values and mineral concentration of thirteen tree and shrub species in Ghana

Obtaining accurate and reliable information on biomass characteristics of tree species is important as it aids in selecting plant species that optimize fuel production for bioenergy. In this study, the net calorific value (NCV) and mineral concentration of 13 plant species selected from the Guinea savanna ecological zone of Ghana were investigated. Significant variation in NCV across the species components was found, with branch wood from most of the species exhibiting higher values compared to stem wood or the bark tissues. Accurate and reliable information on plant biomass could therefore be obtained through plant partitioning. High mobility of Zn and Pb after uptake was observed in the studied species. Apart from Cd whose concentrations in the species exceeded the recommended levels, no toxic levels were observed for the rest of the heavy metals. Thus, the major drawbacks in the use of the species as biomass resource are their higher concentrations of Cd and to some extent, higher ash contents. On account of the relatively high NCV, low ash content and low mineral concentrations, D. microcarpum, and C. febrifuga were found to be most suitable candidates for biomass production and subsequent bioenergy optimization in the Guinea savanna of Ghana.     

Particleboard made from hammer milled black spruce bark residues

Summary  The disposal of bark residues is an important problem for the forest industry. An important proportion of the bark produced by the paper and lumber industries is used for energy production, but a significant amount of bark is still unused. The objective of this study was to determine the technical feasibility of making particleboards from black spruce bark residues bonded with urea formaldehyde resin and meeting the indoor performance requirements for wood particleboards. In the positive case, this would define a new use for black spruce bark residues. Fresh black spruce bark residues were obtained from a sawmill located in the northeast part of the province of Quebec, Canada. The bark was kiln-dried at 60 °C, the particles were generated from a hammermill and sieved. Particles from 0.02 to 2.0 mm were used in the surface layers and particles from 2.0 to 6.0 mm were used in the core layer. Particleboards of 540 × 560 × 16 mm were made with a laboratory hot press following a factorial design with two manufacturing variables at three levels: (1) wood particles content of the surface layers (0, 25, 50 percent); and (2) UF resin content of the surface layers (12, 14 and 16 percent) with a UF resin content in the core of 8 percent. This resulted in a factorial design of 9 different combinations repeated 3 times for a total of 27 boards. It was observed that the heating kinetics varied according to the wood particles content in the surface layers. The compression ratio of the mat and the board internal bond, modulus of elasticity, modulus of rupture, linear expansion and thickness swell were determined. The results show that it is technically possible to make particleboard from bark residues meeting the American National Standard Institute indoor requirement for wood particleboard under certain conditions. The modulus of rupture of the boards was the most critical property in this study. The best mechanical properties were obtained with a 50 percent wood content and 14 percent resin content in the surface layers. The particleboards produced in this study did not meet the minimal requirements for linear expansion. The temperature measurements performed in the core of the mat during hot pressing show that heat transfer improves with an increase in wood particles content in the surface layers. Received 15 June 1998     

杨树冰核活性细菌溃疡病的病理和生理机制(英文)

在1997-1999年间,利用Bier, X.H、波钦诺克、王敬文、史瑞和等人的研究方法,分别对不同品种杨树如:美×青、A100、小黑14、黑小2、613、北京605等接种冰核活性细菌,并对接种前后树皮含水量、相对膨胀度、木质素、苯丙氨酸解氨酶(PAL)活性、电解质渗出率以及无机元素等进行了测定。结果表明:冰核细菌溃疡病发生后,树皮含水率降低,而膨胀度(RT值)升高;树皮内电解质渗出率增加,而在-4 C和5 C时渗出率最高;木质素的含量也有所增加,且与品种的抗病性呈正相关;苯丙氨酸解氨酶活性也有所增加,且与品种的抗病性呈正相关;Cu、Fe含量显著下降,K、Zn含量显著增加,但Mn、Ca、Mg含量变化不大。     

Chloride content and biomass partitioning in Eucalyptus hybrids grown on saline sites

Eucalyptus camaldulensis × globulus and E. camaldulensis × grandis hybrids have been developed to combine the salt–waterlogging tolerance and high-quality wood fibre of their respective parents. The aim is to develop trees that will grow in relatively dry and/or saline environments and provide commercial wood products. Previous studies indicate that the hybrids exhibit faster growth than either of their pure species parents, and that there are significant differences in growth rates between them. We undertook a comparative study of the partitioning of above-ground biomass (AGB) to examine biomass and chloride (Cl) allocation of trees growing on two saline-irrigated sites in south-eastern Australia. Eucalyptus camaldulensis × globulus had a higher proportion of AGB in leaves (20–29% cf. 15–16%), and lower proportion in live branches (3–10% cf. 6–14%) than E. camaldulensis × grandis. The concentration of Cl was highest in the stembark (4.2–9.6 g kg⁻¹) and lowest in the stemwood (0.6–2.0 g kg⁻¹), suggesting that trees can export Cl through bark shedding. Total Cl content was strongly related to volume under bark (R² = 0.99), and differences in partitioning of Cl into tree components differed between the hybrids in the same way as AGB. Preferential partitioning of Cl to live branches rather than foliage in E. camaldulensis × grandis suggests that this hybrid may be compartmentalising Cl to reduce the risk of Cl toxicity in the leaves.     

Initial Moisture Content and Density and Drying Rate of Three Pine Species Growing in the Natal Midlands

In this the first of a two-part report, results are given of investigations into the vertical distribution of the moisture content and density of wood and bark, as well as into bark thickness, bark mass and bark volume of two age groups of Pinus elliottii and P. patula trees and one of P. taeda. Variation in wood and bark properties was affected more by position in the stem than by species and age. This precludes the determination of reliable mass/volume conversion figures if stem position is not taken into consideration. The mass loss of logs of the above species after various periods of drying and the development of mass/volume conversion figures will form part of a further report.     

Proportion of above-ground biomass in commercial logs and residues following the harvest of five commercial forest species in Australia

A significant factor influencing the contribution of wood products to carbon (C) storage is the proportion of above-ground tree biomass (AGB) recovered in commercial logs at harvest. This study examined the proportion of AGB in logs and residues at the harvest of radiata pine, cypress pine, blackbutt, spotted gum and messmate. Messmate and spotted gum had the highest variation in stem diameter and height. The average AGB ranged from 2000 to 3000 kg for the hardwoods and 220–1000 kg for the softwoods. Blackbutt had the overall lowest proportion of AGB recovered in commercial logs (45.5%) and radiata pine the highest (65%). The proportion of AGB in the bark of the hardwoods was significantly lower than in the softwoods. The proportion of the AGB in forest residues following harvest ranged from 30 to 55% depending on the species.The proportion of AGB recovered in high quality commercial logs ranged from 15% for spotted gum to 63% for radiata pine. The differences were due to the natural characteristics of the selected species and variations in regional market availability. The highest retention rates of AGB in high quality hardwood commercial logs were obtained for trees with DBH between 500 and 600 mm (messmate and blackbutt) and greater than 600 mm for spotted gum.The mean moisture content of the wood of the different species ranged from 35 to 50%. Messmate and radiata pine logs had the highest moisture content (48 and 50%, respectively).The C concentration of blackbutt, radiata pine and cypress pine was slightly higher than 50%. The softwoods had significantly higher C concentration than the hardwoods. The C concentration between positions (cross-section, sapwood and heartwood) also varied for the different species.The highest proportion of the above-ground C was in the debarked log for all species with the exception of blackbutt.The cellulose concentration of the wood ranged from 56 to 64% for hardwoods and 40–52% for the two softwoods. The lignin concentration of the wood ranged from 16 to 19% for the hardwoods and 25–35% for the two softwoods. The hardwood species could not be distinguished from one another based on the cellulose, hemicellulose and lignin concentration, but within the softwood species, cypress pine and radiata pine formed separate clusters.     

Allometry, biomass, and chemical content of Novel African Tulip Tree (Spathodea campanulata) Forests in Puerto Rico

The African tulip tree, Spathodea campanulata, the most common tree in Puerto Rico, forms novel forest types with mixtures of native and other introduced tree species. Novel forests increase in area in response to human activity and there is no information about their biomass accumulation and nutrient cycling. We established allometric relationships and chemically analyzed plant parts of African tulip trees to determine the concentration and standing stock of chemical elements (C, N, P, K, Ca, Mg, S, Mn, Al, Fe, Na), and ash. Trees ranged in diameter at breast height from 8 to 85 cm and in height from 8.8 to 28 m. The concentrations of N, P, K, and Ca in leaves of the African tulip tree were similar to those of the native pioneer Cecropia schreberiana and higher than those of mature forest tree species in Puerto Rico. The over bark wood volume of African tulip trees in nine forest stands where it was dominant ranged from 163 to 849 m³/ha. Aboveground biomass ranged from 60 to 296 Mg/ha, and N and P stocks ranged from 190 to 988 and 32 to 137 kg/ha, respectively. Novel forests on abandoned agricultural lands can store more biomass and elements than native and plantation forest stands of similar age.     

Screening of extracts of Japanese woods for melanin biosynthesis inhibition

The effects of 120 methanol extracts prepared from bark and heartwood of 69 types of Japanese wood on the melanin production of B16 melanoma cells were examined. The melanin content of B16 melanoma cells was determined spectrophotometrically at 405nm. The extracts were also examined for their effects on cell viability. We found that the methanol extracts of Fagus crenata (buna, wood, 100μg/ml), Sapium sebiferum (Nankinhaze, wood, bark, 10μg/ml), and Zelkova serrata (keyaki, wood, 10μg/ml) greatly inhibited the melanin production of B16 melanoma cells without significant cytotoxicity. However, these extracts did not inhibit tyrosinase activity at the concentration of 100μg/ml. These findings indicate that the depigmenting mechanism of these extracts involves the suppression of some pigmenting signals in stimulating melanogenesis rather than the inhibition of tyrosinase activity. Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003     

老秃顶子国家级自然保护区小蠹虫发生危害调查

在老秃顶子国家级自然保护区共采到小蠹虫29种,隶属4亚科15属,其中红松根小蠹Hy-lastes plumbeusBlandford、东北四眼小蠹Polygraphus sachalinensisEggers、中穴星坑小蠹Pityo-genes chalcographasLinnaeus、落叶松八齿小蠹IpssubelongatusMotschuleky、六齿小蠹I.acuminatusGyllenhal等为优势种,主要危害衰弱木、濒死木、枯萎木及风倒雪压木等,少数种类如纵坑切梢小蠹Tomicus piniperda Linnaeus、黄须球小蠹Sphaerotrypes coimbatorensisStebblng等危害健康树木。不同海拔高度及不同类型的林分中,小蠹虫的种类存在明显差异。及时清除、集中处理风倒木是控制虫源,减轻危害的重要措施。