Transpiration along an age series of Eucalyptus globulus plantations in southeastern Australia

Many of the world's Eucalyptus plantations are grown on short rotations of 15 years or less, which often covers the most rapid phase of stand development and peaks in growth rates and leaf areas. Since transpiration is related to stand leaf area these short rotations that make use of rapid early growth rates, may also maximise plantation water use, which has implications for predicting their water requirements and impacts on catchment hydrology. This study examined the transpiration, leaf area and growth rates of Eucalyptus globulus Labill. plantations aged 2–8 years. Transpiration (E), estimated using the heat pulse technique, increased from 0.4 mm day⁻¹ at age 2 years to a peak of about 1.6–1.9 mm day⁻¹ in stands aged 5–7 years. This was associated with similar trends for stand leaf area index (LAI) and periodic annual increments of aboveground biomass, which both peaked at about age 4–6 years resulting in a linear relationship between E and LAI. While stand sapwood areas were continuing to increase at age 8 years, E was already declining due to reductions in sap velocity, from 13.5 cm h⁻¹ at age 2 years to 6.3 cm h⁻¹ at age 8 years and reduced sapwood area growth rates. Trees compensated for this reduction in sap velocity with declines in the leaf area (A_L) to sapwood area (A_S) relationship (A_L:A_S) with age. There was also a reduction in growth efficiency (aboveground biomass increment per LAI) with age. However, reductions in WUE were small after age 4 years, which explained the linear relationship between E and LAI. If E continues to decline successive short rotation lengths may not only make use of rapid early growth rates but could also increase plantation water use compared to longer rotations over the same period of time.     

Shifting cultivation effects on creek water quality around Barkal Upazila in Chittagong Hill Tracts, Bangladesh

We report the effects of shifting cultivation on water quality in 16 creeks investigated once in 2007 and twice in 2008 in 16 apparently similar small neighboring watersheds,each of 3 to 5 ha,at four locations around Barkal sub-district under Rangamati District of Chittagong Hill Tracts in Bangladesh.Concentrations of SO 4 2and K +,and pH in creek water were lower,and NO 3-N and Na + concentrations were higher in shifting-cultivation land compared to land with either plantation or natural forest or a combination of these cover types.Shifting cultivation effects on some water quality parameters were not significant due to change in land cover of the watershed between two sampling periods either through introduction of planted tree species or naturally regenerated vegetation.Conductivity and concentrations of HCO 3,PO 4 3,Ca 2+ and Mg 2+ in creek water showed no definite trend between shifting cultivation and the other land cover types.At one area near the Forest Range Office of Barkal,creek water pH was 5.8 under land cover with a combination of shifting cultivation and plantation.At this area Na + concentration in shifting-cultivation land ranged from 32.33 to 33.00 mg L-1 and in vegetated area from 25.00 to 30.50 mg L-1 in 2007.At another area,Chaliatali Chara,SO 4 2concentration in a shifting-cultivation watershed ranged from 4.46 to 10.51 mg L-1,lower than in a vegetated watershed that ranged from 11.69 to 19.98 mg L-1 in 2007.SO 4 2concentration in this shifting-cultivation area ranged from 1.28 to 1.37 mg L-1 and in the vegetated area from 1.37 to 3.50 mg L-1 in 2008.     

Effect of density of trees on drag exerted on trees in river channels

Recently, riparian forests have attracted attention as they are effective for ecological preservation and landscape enhancement. Uses of such forests in flood prevention, sediment control, and erosion control works have been actively promoted. This study aims to clarify the effect of density of riparian trees on drag exerted on trees along river channels under the regime of bed load transport. Hydraulic model experiments were performed using a straight channel, and the methods to calculate the drag coefficient necessary for deriving drag exerted on trees were studied. Previous studies have stated that the drag coefficient of a cylinder is fairly constant when Reynolds number,R _e, is between 10³ and 10⁵ (e.g., Schlichting, 1979). This study clarified, however, that in cases of relatively dense arrangements of model trees (cylinders), the drag coefficient varies greatly with the density of the trees. As such, correlation between the drag coefficient and Reynolds number was found to be slight. Test results indicated that the drag coefficient of trees,C _d, correlates strongly with the coefficient of velocity,U′/U _* ′, friction factor of the channel bed,f′, and roughness concentration of trees × flow depth,aH′ or ratio of the area occupied by trees,λ. Furthermore, the drag coefficient,C _d, was also found to be slightly correlated with the gradient of the channel bed,I. Equations using either of the following parameters were obtained for deriving the drag coefficient,C _d, based on the experiment results:aH′; λ; U′/U _* ′; and Froude numberF _r. These equations allow fairly accurate calculation of drag exerted on trees.     

Variations of root hydraulic conductance of Fraxinus mandshurica seedlings in different concentrations of NH4NO3 solution

Absorbing water from soil by roots in vascular plants is an important physiological function and plays an essential role on their water balance. The root hydraulic conductance (L _P) determined by radical water transport inside the root is a major influence on the shoot water status, plant growth, and development. However, a few studies have focused on the effect of different substances on L _P of roots, and the role of radical water transport was poorly understood. Based on the pressure-flux approach, this study used the roots of Fraxinus mandshurica seedlings with different treatments, i.e., distilled water, NH₄NO₃ solution, and HgCl₂ to determine the effect of various substances on L _P of roots. The objectives are: 1) to evaluate the difference in L _P occurred between distilled water and NH₄NO₃ solution with various concentrations; and 2) to examine the changes of L _P under distilled water and NH₄NO₃ solution with various concentrations after HgCl₂ treatment. The results showed that L _P of roots were 18.85×10⁻⁸ m/(s·MPa) in distilled water, 31.25–34.15×10⁻⁸ m/(s·MPa) in four NH₄NO₃ solutions (2, 4, 8 and 16 mmol/L), 14.69×10⁻⁸ m/(s·MPa) in distilled water after HgCl₂-treated, and 9.63–13.57×10⁻⁸ m/(s·MPa) in four NH₄NO₃ solutions after HgCl₂-treated, respectively. Aquaporins play an important role in regulating water uptake and transport in roots. NH₄ ⁺ and NO₃ ⁻ could stimulate activity of aquaporins, and L _P of roots in NH₄NO₃ solution was distinctly 77% higher than in distilled water. Nevertheless, Hg²⁺ can inhibit activity of aquaporins, and and L _P of roots decreased 22% in distilled water and 68% in NH₄NO₃ solution after treatment by HgCl₂ respectively. These evidences suggested that both Hg²⁺-sensitive aquaporins and ion channels existing in the protoplasm and vacuole membranes could regulate root water uptake, transport, and integral plant water balance. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(5): 706–712 [译自: 植物生态学报, 2005, 29(5): 706–712]     

Mangroves as a coastal protection from waves in the Tong King delta,Vietnam

The wave reduction (wave period; 5–8 sec.) was investigated in amangrove reforestation area (Kandelia candel) close toaquaculture ponds in the Tong King delta, Vietnam.On one site where only young mangrove trees grew, the wavereduction due to the drag force on the trees was hardlyeffective. On the other site where mangrove trees weresufficiently tall, the rate of wave reduction per 100 m was aslarge as 20%. Due to the high density of vegetation distributedthroughout the whole water depth, the effect of wave reductionwas large even when the water depth increased. These resultsdemonstrate the usefulness of mangrove reforestation for coastalprotection.     

松褐天牛成虫高毒力绿僵菌菌株筛选及液体振荡培养条件

对3株绿僵菌菌株通过不同温度水浴处理,发现了孢子的萌发条件;并开展了3菌株对松褐天牛成虫的毒力测定,筛选出Ma₇₈₉菌株的致病力较强。通过正交试验对其液体振荡培养条件进行了分析,选出了菌丝体生长最适培养基为蔗糖20 g·L^-1,酵母粉10 g·L^-1,KH₂PO₄ 3.0 g·L^-1,MgSO₄·7H₂O 1.0 g·L^-1,CaCl₂ 0.5 g·L^-1;培养液生孢子最适培养基为蔗糖20 g·L^-1,蛋白胨10 g·L^-1,KH₂PO₄ 1.5 g·L^-1,MgSO₄·7H₂O 2.0 g·L^-1,CaCl₂ 0.5 g·L^-1。     

Elastic moduli and stiffness optimization in four-point bending of wood-based sandwich panel for use as structural insulated walls and floors

Several wood-based sandwich panels with low-density fiberboard core were developed for structural insulated walls and floors, with different face material, panel thickness, and core density. The elastic moduli with and without shear effect (E _L, E ₀) and shear modulus (G_b) were evaluated in four-point bending. Generally, the stiffer face, thicker panel, and higher core density were advantageous in flexural and shear rigidity for structural use, but the weight control was critical for insulation. Therefore, optimum designs of some virtual sandwich structures were analyzed for bending stiffness in relation to weight for fixed core densities, considering the manufactured-panel designs. As a result, the plywood-faced sandwich panel with a panel thickness of 95 mm (PSW-T100), with insulation performance that had been previously confirmed, was most advantageous at a panel density of 430 kg/m³, showing the highest flexural rigidity (E _L I = 13 × 10⁻⁶ GNm²) among these panels, where E _L, E ₀, and G _b were 3.5, 5.5, and 0.038 GN/m², respectively. The panel was found to be closest to the optimum design, which meant that its core and face thickness were optimum for stiffness with minimum density. The panel also provided enough internal bond strength and an excellent dimensional stability. The panel was the most feasible for structural insulation use with the weight-saving structure.     

Characterization of the ashes of Nigerian red and white mangrove woods

Summary An investigation of the analytical characterization of ashes of Nigerian red and white mangrove woods was carried out. The ashes obtained from the woods were subjected to intense heating in water to extract the chemical constituents. Some quantitiy of rock salt was also dissolved in water and analysed. The solution obtained from the ashes were differently analysed for K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^–, SO₄, PO₄, NO₃ and total solid. The pH of each sample solution was measured. Various concentrations of these cations and anions were obtained and they were found in each case to be more than those obtained from rock salt. Solutions obtained from the ashes of red and white mangrove woods have wide applications particularly in Nigeria as tasty food additive and in softening and accelerating the cooking time of yam, plantain and beans in particular.     

迎风向防风林带宽对风速减弱的作用

通过在日本扎晃人学水压力工程实验室开展的埃菲尔型非循环风洞试验,研究了防风林阻尼变化及不同林带宽的整体阻力系数,阐明在迎风向上防风林带宽对风速减弱的作用.以二维雷诺时均N-S方程-k-ε吨扰动闭合模型数字地研究了不同防风林带宽的流量场变化.结果表明,防风林对风的阻力随林带宽增加而增加,但是整体阻尼系数略微降低.整体阻尼系数Cd、防风林带宽W和林高H之间满足方程Cd=kd(W/H)-b(kd,b:常数).数字模拟结果表明,防风林带宽度明显影响最小风速值及其位置.随着防风林带宽度的增加,风速下降15%-22%.     

An irreversible thermodynamics model for unsteady-state nonisothermal moisture diffusion in wood

Summary A model that predicts heat and moisture transfer through wood in the hygroscopic range and which is based on the principles of irreversible thermodynamics, was evaluated with unsteady-state nonisothermal moisture desorption experimental data. The model predicted the phenomenon of thermal diffusion during the initial stages of desorption and results in a very good simulation of the desorption curve and the center's temperature change with time.Symbols C_p specific heat of air (= 0.24 cal/g K @ 70 °C) - C_T specific heat of wood, cal/g K - D transverse diffusion coefficient, cm²/s - E_b activation energy, cal/mol - E_o heat of vaporization, cal/mol - E_L differential heat of sorption, cal/mol - G specific gravity of wood - H relative humidity, % - h_T convective heat transfer coefficient, cal/cm² s K - h_c convective mass transfer coefficient based on the concentration of moisture in wood, cm/s - h_v convective mass transfer coefficient based on the concentration of moisture in the air in equilibrium with the wood surface, cm/s - K_M coefficient for diffusion due to moisture gradient, g/cm s % - K_T transverse thermal conductivity coefficient, cal/cm K s - M moisture content, % - P_o saturated vapor pressure, atm - R universal gas constant, cal/mol K (= 82.056 cm³ atm/mol K) - t time, s - T temperature, K - x distance, cm Greek Letters evaporation or condensation criterion - wood density, g/cm³ - _W water density (=1), g/cm³ - _a air density, g/cm³ Department of Wood Science and Forest Products Virginia Polytechnic Institute and State University Blackburg, Virginia 24061-0503     

Estimation ofPinus radiata D. Don clear wood properties by near-infrared spectroscopy

The use of calibrated near-infrared (NIR) spectroscopy for predicting of a range of solid wood properties is described. The methods developed are applicable to large-scale nondestructive forest resource assessment and to tree breeding and silviculture programs. A series ofPinus radiata D. Don (radiata pine) samples were characterized in terms of density, longitudinal modulus of elasticity (E _L), and microfibril angle (MFA). NIR spectra were obtained from the radial/longitudinal face of each sample and used to generate calibrations for the measured physical properties. The relations between laboratory-determined data and NIR fitted data were good in all cases, with coefficients of determination (R ²) ranging from 0.68 for 100/MFA to 0.94 for density_strip. A good relation (R ² = 0.83) was also obtained forE _L estimated using data collected by SilviScan-2. The finding suggests that an NIR instrument could be calibrated to estimate theE _L of increment cores based on SilviScan data. In view of the rapidly expanding range of applications for this technique, it is concluded that appropriately calibrated NIR spectroscopy could form the basis of a testing instrument capable of predicting a range of properties from a single spectrum obtained from the product or from the raw material.     

中亚热带钱江流域天然次生林集水区溪流与降水水质比较

对浙江钱江源生态站大气降水和天然次生林生态系统的径流水质指标进行逐月取样测试和对比分析.结果表明:天然次生林集水区水体中溶解氧含量年平均值达到8.10 mg·L-1,是大气降水的1.12倍;总氮含量年平均值达7.68 mg·L-1,是大气降水的4.49倍.大气降水的生化需氧量年平均值达2.10 mg·L-1,是天然次生...     

Measurement of the dynamic modulus of elasticity of wood panels

This study investigated the dynamic modulus of elasticity (DMOE) of wood panels of Fraxinus mandshurica, Pinus koraiensis, and Juglans mandshurica using the natural frequency measurement system of fast Fourier transform (FFT). The results were compared with the static modulus of elasticity (E _S) tested by a mechanical test machine. The results show a significant correlation between E _S, transverse vibration DMOE (E _F), and longitudinal vibration DMOE (E _L). For all of these species, the correlation between E _S, E _F and E _L is more significant than the individual species, which indicated that the FFT method is universal. The correlations between E _S and sample’s density (ρ) are significant, but the correlation coefficient of E _S and ρ is lower than those between E _F, E _L and E _S. The E _S of wood is more accurately tested by the analysis based on FFT measurement than by the estimation based on density. __________ Translated from Scientia Silvae Sinicae, 2005, 41(6): 126–131 [译自: 林业科学, 2005, 41(6): 126–131]     

Stand-scale transpiration estimates in a Moso bamboo forest: II. Comparison with coniferous forests

In western Japan, Moso bamboo (Phyllostachys pubescens) forests have been expanding by replacing surrounding vegetation such as coniferous plantation forests and natural broadleaved forests. It has been speculated that the replacement of surrounding vegetation by bamboo forests could alter the vegetation water cycle and available water resources. We quantified stand-scale transpiration (E) in a bamboo forest on the basis of sap-flux measurements and compared the E value with values for coniferous forests. The annual E was estimated to be 567 mm. Seasonal trends in E primarily corresponded to seasonal trends in the vapor pressure deficit. Annual E for the bamboo forest was higher than that for the coniferous forests by 12% of annual precipitation (P). This difference in annual E is comparable with the difference in annual interception evaporation (I) relative to P between bamboo and coniferous forests; previous studies reported lower I for bamboo forests by ∼10% of P. Thus, the sum of E and I was comparable for bamboo and coniferous forests. As this study is the first measuring E of bamboo forests, further studies are required to examine the generality of our results.     

Wind fields in heterogeneous conifer canopies: parameterisation of momentum absorption using high-resolution 3D vegetation scans

Applications of flow models to tall plant canopies are limited, amongst other factors, by the lack of detailed information on vegetation structure. A method is presented to record 3D vegetation structure and make this information applicable to the derivation of turbulence parameters suitable for flow models. The relationship between wind speed, drag coefficient (C _D ) and plant area density (PAD) was experimentally investigated in a mixed conifer forest in the lower part of the Eastern Ore Mountains. Essential information was gathered by collecting multi-level high-frequency wind velocity measurements and a dense 3D representation of the forest was obtained from terrestrial laser scanner data. Wind speed dependence or streamlining was observed for most of the wind directions. Edge effects, i.e. the influence of the here not regarded pressure gradient and the advective terms of the momentum equation, are assumed to cause this heterogeneity. Contrary to the hypothetic shelter effect, which would reduce the drag on sheltered plant parts, the calculated profiles of drag coefficients revealed an increasing C _D with PAD (i.e. a dependence on canopy and plant structure).     

Sedimentation in Mangrove Forests

The tidal currents in mangrove forests are impeded by the friction caused by the high vegetation density. The tidal currents are also complex comprising eddies, jets and stagnation zones. The sediment particles carried in suspension into the forest during tidal inundation are cohesive, mainly clay and fine silt, and form large flocs. These flocs remain in suspension as a result of the turbulence created by the flow around the vegetation. The intensity of sedimentation is largest for trees forming a complex matrix of roots such as Rhizophora sp. and smallest for single trees such as Ceriops sp. The flocs settle in the forest around slack high tide. At ebb tides the water currents are too small to re-entrain this sediment. Hence the inundation of coastal mangrove forests at tidal frequency works as a pump preferentially transporting fine, cohesive sediment from coastal waters to the mangroves. Mangroves are thus not just opportunistic trees colonising mud banks but actively contribute to the creation of mud banks.     

Prediction of timber bending strength on basis of bending stiffness and material homogeneity assessed from dynamic excitation

The potential of utilizing resonance frequencies corresponding to edgewise bending modes for predicting the bending strength of timber is investigated. The research includes measurements of axial and transversal resonance frequencies, laboratory assessment of density, static bending stiffness and bending strength of 105 boards of Norway spruce of dimensions 45?×?145?×?3,600?mm3. It is shown that E _b,1 , (MOE based on the resonance frequency of the first bending mode) gives a higher coefficient of determination to the bending strength than what E _a,1 (MOE based on the first axial resonance frequency) does. It is also shown that resonance frequencies corresponding to higher bending modes can be used in the definition of a new indicating property, the measure of inhomogeneity (MOI). This is a scalar value representing the lack of fit between the true, measured resonance frequencies and the expected (assuming homogeneity) resonance frequencies of a board. The results show that using the MOI as a third indicating property, in addition to E _b,1 and density, increases the coefficient of determination with respect to bending strength from R ²?=?0.69 to R ²?=?0.75.     

Effects of soil moisture and temperature on CH4 oxidation and N2O emission of forest soil

Soil samples were taken from depth of 0–12 cm in the virgin broad-leaved/Korean pine mixed forest in Changbai Mountain in April, 2000. 20 μL·L⁻¹ and 200 μL·L⁻¹ CH₄ and N₂O concentration were supplied for analysis. Laboratory study on CH₄ oxidation and N₂O emission in forest soil showed that fresh soil sample could oxidize atmospheric methane and product N₂O. Air-dried soil sample could not oxidize atmospheric methane, but could product N₂O. However, it could oxidize the supplied methane quickly when its concentration was higher than 20 μL·L⁻¹. The oxidation rate of methane was increased with its initial concentration. An addition of water to dry soil caused large pulse of N₂O emissions within 2 hours. There were curvilinear correlations between N₂O emission and temperature (r²=0.706, p<0.05), and between N₂O emission and water content (r²=0.2968, p <0.05). These suggested temperature and water content were important factors controlling N₂O emission. The correlation between CH₄ oxidization and temperature was also found while CH₄ was supplied 200 μL·L⁻¹ (r²=0.3573, p<0.05). Temperature was an important factor controlling CH₄ oxidation. However, when 20 μL·L⁻¹ CH₄ was supplied, there was no correlation among CH₄ oxidization, N₂O emission, temperature and water content. Foundation item: This paper was supported by Chinese Academy of Sciences. Biography: ZHANG Xiu-jun (1960-), female, Ph. Doctor, lecture in Laboratory of Ecological Process of Trace Substance in Terrestrial Ecosystem, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015, P.R. China. Responsible editor: Song Funan     

施肥配比与芸苔素内酯对油茶生长的影响研究

采用L₉(3⁴)正交试验设计,分别对长林系列3个优良油茶无性系进行施肥配比和叶面喷施芸苔素内酯(BR)试验研究,结果表明:(1)油茶品种是影响油茶各项生长指标的最根本的因素;(2)各因子对地径、冠幅、产量和净光合作用影响权重依次是品种、因子间互作、施肥和芸苔素内酯,施肥对叶绿度影响比因子间互作影响大,而对高生长影响刚好相反;对出籽率影响依次是品种、施肥、芸苔素内酯及因子间互作;(3)18号品系、N₂P₂K₂和0.067 mg·L^-1 芸苔素内酯浓度组合时,树高、冠幅和出籽率表现最好;4号品系、N₁P₁K₁和0.067 mg·L^-1芸苔素内酯组合时,地径增长、叶绿度和产量最大;4号品系、N₂P₂K₂和0.033 mg·L^-1芸苔素内酯组合时,日均净光合速率最大。     

东北刺人参组培快繁培养基的筛选

东北刺人参(Oplopanax elatusNakai.)又称刺参,五加科(Araliaceae)多年生落叶灌木,其干燥根和茎均可入药,是一种用途广泛的中药材。近些年来,医药科研工作者对其成分及药理进行了大量的试验和研究,其结果表明,根、茎入药有类似于人参的作用,可用于治疗神经衰弱、低血压和风湿性