Modeling diameter distributions of Gmelina arborea plantation in Omo Forest Reserve,Nigeria with Johnson’s SB

Diameter distribution modeling is an essential tool for obtaining reliable information on the structure, growth, and yield of forests. However, this tool has not been duly utilized in many forest plantations, especially in Nigeria. Thus, this article presents the effectiveness of using the Johnson S_B function for modeling diameter distributions of a Gmelina arborea plantation in Omo Forest Reserve, Nigeria. Fifty plots of 0.04 ha were randomly selected across three age series. All trees with DBH ≥ 5.0 cm in the selected plots were measured. Three fitting methods for the S_B distribution were compared: conditional maximum likelihood (CML), moments (MOM), and Knoebel and Burkhart (KB) methods. The parameter recovery model (PRM) was used to recover the parameters of the distribution. The assessment was based on Kolmogorov-Smirnov (K-S), mean square error (MSE), mean absolute error (MAE), and bias. The results showed that the underlying diameter distribution of the Gmelina arborea followed the Johnson’s S_B distribution fitted with MOM. The number of rejections by the K-S test was zero for MOM and CML. The mean K-S value for MOM was statistically different from CML and KB methods. The results obtained after recovering the parameters of the S_B distribution were comparable with the real distributions of the Gmelina arborea stand.     

Structure of mixed Picea abies (L) Karst,and Betula pendula Roth and Betula pubescens Ehrh. stands in South and middle Sweden

Observed diameter distributions of forest stands are adapted to the Johnson S _b probability function. The stands investigated are untreated mixed stands of Norway spruce (Picea abies (L.) Karst.) and birch (Betula pendula Roth and Betula pubescens Ehrh.) aged between 20 and 32 years. The adaptation of the Johnson S_b probability function is made both on mixed spruce and birch, and on each species separately. Altogether 156 observations were tested with observed distributions against calculated distributions in the Kolmo‐gorov‐Smirnov test. The fractiles are predicted with multiple regression and two multivari‐ate techniques, simultaneous‐equation models (multivariate regression) and partial least squares with latent variables. The independent variables are characteristics of site and stand. Both multivariate methods predict diameter distribution well when tested.     

Application of the SB distribution to the prediction of concomitant wood properties

Summary It is frequently the case that multiple strength properties of structural wood members are simultaneously needed in design or research. A method has been developed to predict the probability distribution of concomitant material properties of wood from a knowledge of some correlated, nondestructive material property. The method developed in this study is based on properties of the univariate S_B distribution and the bivariate S_BB distribution. The technique involves a priori knowledge of the correlation relationship between a nondestructive parameter and the strength parameter for the two concomitant properties in question. A relationship is developed between the two nondestructive parameters and a simulation procedure is presented to predict either concomitant property from a single nondestructive measurement. The results showed that when a single parameter was predicted directly from a correlated variable, the simulated and experimental distributions were very similar (average error 3–4%). This result confirms previous findings. For the prediction of the concomitant property from an indirect relationship with another parameter, the absolute value of the average error was about 13%.     

A flexible modeling of irregular diameter structure for the volume estimation of forest stands

Simple distribution models (SDMs) have deficiencies in portraying irregular forest diameter structure. This paper introduces mixture distribution models (MDMs) to improve the estimation accuracy of stand volume of Siberian larch (Larix sibirica Ledeb.) forests. Stand volume was estimated by combining the suitable diameter mixture model and diameter–height model. Appropriate mixture models are derived by integrating multiple SDMs of Burr III and XII, Johnson S_B, Weibull or lognormal probability density functions (pdf) that satisfied the criteria of goodness of fit tests. Results showed that the average bias of volume estimation for all of the study plots using SDM and MDM approaches are underestimated by 6.93 and 2.42 m³, respectively. Each of the estimates is equivalent to an estimation error of 25.59 ± 18.18 and 7.08 ± 2.97 %. This suggests that the MDM approach is a more flexible and suitable modeling technique for forest volume estimation, in particular for forests that have been frequently disturbed by natural events.     

浙江省毛竹直径与年龄的二元Weibull分布模型

利用2004年复查的浙江省森林资源连续清查体系4250个固定样地中的245个毛竹纯林样地数据,用具有严格概率模型性质的二元Weibull分布模型描述浙江省毛竹直径与年龄的二维结构,并讨论二元Weibull分布模型的生成函数,给出几个不同形式的表达式,指出模型良好的概率模型性质。一元Weibull分布模型的直径、年龄模型分别是二元模型的边际分布,而且用边际分布求得的参数与用联合分布求得的参数也很接近。本研究是省级地域的毛竹宏观模型,该模型也可尝试应用到林分水平,以及其他类型森林。     

Effects of winter selective tree harvest on soil microclimate and surface CO2 flux of a northern hardwood forest

Soil surface CO₂ flux (S_flux) is the second largest terrestrial ecosystem carbon flux, and may be affected by forest harvest. The effects of clearcutting on S_flux have been studied, but little is known about the effect of alternative harvesting methods such as selective tree harvest on S_flux. We measured S_flux before and after (i) the creation of forest canopy gaps (simulating group tree selection harvests) and (ii) mechanized winter harvest but no tree removal (simulating ground disturbance associated with logging). The experiment was carried out in a sugar maple dominated forest in the Flambeau River State Forest, Wisconsin. Pre-treatment measurements of soil moisture, temperature and S_flux were measured throughout the growing season of 2006. In January–February 2007, a harvester created the canopy gaps (200–380 m²). The mechanization treatment consisted of the harvester traveling through the plots for a similar amount of time as the gap plots, but no trees were cut. Soil moisture and temperature and S_flux were measured throughout the growing season for 1 year prior to harvest and for 2 years after harvest. Soil moisture and temperature were significantly greater in the gap than mechanized and control treatments. Instantaneous S_flux was positively correlated to soil moisture and soil temperature at 2 and 10 cm, but temperature at 10 cm was the single best predictor. Annual S_flux was not significantly different among treatments prior to winter 2007 harvest, and was not significantly different among treatments after harvest. Annual (+1 std. err.) S_flux averaged 967 + 72, 1011 + 72, and 1012 + 72 g C m⁻² year⁻¹ in the control, mechanized and gap treatments, respectively, for the 2-year post-treatment period. The results from this study suggest selective group tree harvest significantly increases soil moisture and temperature but does not significantly influence S_flux.     

Ultrastructure of the S2 layer in relation to lignin distribution inPinus radiata tracheids

The ultrastructure of the S₂ layer in relation to its lignin distribution was examined using transmission electron microscopy in the tracheids ofPinus radiata. The S₂ layer had a striated appearance at low magnification. Observations at higher magnifications showed lignin to be distributed inhomogeneously in this layer, appearing as a mosaic of electron-dense and electron-lucent regions. These regions are scattered, showing a pattern of often interconnecting sinuous features in a predominantly radial profile. The significance of these features of the S₂ layer is discussed, particularly in relation to the available information from recent ultrastructural observations on the appearance of cellulose microfibrils and the pattern of their distribution in the S₂ layer using rapid freeze-deep etching in conjunction with transmission electron microscopy. Predictions are made as to the likely distribution and arrangement of cellulose microfibrils in the S₂ layer based on the pattern of lignin distribution observed in this layer.     

Characteristics of the temperature coefficient, Q 10, for the respiration of non-photosynthetic organs and soils of forest ecosystems

The temperature coefficient, Q ₁₀ (fractional change in rate with a 10°C increase in temperature) describes the temperature sensitivity of soils, roots, and stems, as well as their possible performance in global warming processes. It is also a necessary parameter for the estimation of total CO₂ efflux from each element. A number of studies have focused on Q ₁₀ values to date; however, their conclusions are not universal and do not always agree. A review of these reported Q ₁₀ values therefore becomes necessary and important for a global understanding of the temperature sensitivity of different forest types and elements. The aims of our present paper are, first, to find the frequency distribution pattern of soils, roots, and stems (branches) and compare their temperature sensitivity; then, to find the Q ₁₀ differences between conifer and deciduous tree species and the effect of methodology on Q ₁₀ values; finally we want to give a perspective on future Q ₁₀-related studies. We found that most Q ₁₀ values of each element were concentrated in a relatively narrow range despite a total data distribution over quite a wide range. For soil respiration, the median Q ₁₀ value was 2.74 and the center of the frequency distribution was between 2.0 and 2.5 with a percentage of 23%. Most of the data (>80%) were within the range from 1.0 to 4.0. The median Q ₁₀ value for root respiration was 2.40 and the center of the frequency distribution was from 2.5 to 3.0 with a percentage of 33%. Most of the results (>80%) ranged from 1.0 to 3.0. For stem respiration, the median Q ₁₀ value was 1.91 and the frequency distribution was concentrated between 1.5 and 2.0. Over 90% of the data ranged from 1.0 to 3.0. Obvious differences in Q ₁₀ value were found between different elements, stem < root < soil including root < soil excluding root. The differences between woody organisms of stems, roots, and soils excluding roots were statistically significant (p<0.05), indicating that heterotrophic respiration from microorganism activity may be more sensitive to global warming. The duration of the period with leaves slightly affects the temperature sensitivity of woody organisms since the Q ₁₀ values for root and stem of coniferous evergreen trees did not differ significantly from deciduous trees (p>0.10). CO₂ analytical methods (soda lime absorption method, IRGA (Infra-read gas analysis), and chromatograph analysis) and root separation methods (excised root and trenched box) slightly affected the Q ₁₀ values of soil and root respiration (p>0.10), but an in vitro measurement of stem respiration yielded a significantly higher Q ₁₀ value than an in vivo method (p<0.05). In general, although the Q ₁₀ values of non-photosynthetic organisms stayed within a relatively conservative range, considerable variation between and within elements were still detectable. Accordingly, attention should be paid to the quantitative estimation of total CO₂ efflux by Q ₁₀-related models. In future studies, the biochemical factors and the environmental and biological factors controlling respiration should be emphasized for precise estimation of total CO₂ efflux. The difficulty is how to clarify the underlying mechanism for fluctuations of Q ₁₀ values for one specific habitat and element (e.g. temperature acclimation or adaptation of Q ₁₀ values) and then allow the Q ₁₀ values to be more conservative for representation of temperature sensitivity in global warming processes. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(4) [译自:植物生态学报, 2005, 29 (4)]     

Soil and microbial respiration in a loblolly pine plantation in response to seven years of irrigation and fertilization

Because soil CO₂ efflux or soil respiration (R_S) is the major component of forest carbon fluxes, the effects of forest management on R_S and microbial biomass carbon (C), microbial respiration (R_H), microbial activity and fine root biomass were studied over two years in a loblolly pine (Pinus taeda L.) plantation located near Aiken, SC. Stands were six-years-old at the beginning of the study and were subjected to irrigation (no irrigation versus irrigation) and fertilization (no fertilization versus fertilization) treatments since planting. Soil respiration ranged from 2 to 6 μmol m⁻² s⁻¹ and was strongly and linearly related to soil temperature. Soil moisture and C inputs to the soil (coarse woody debris and litter mass) which may influence R_H were significantly but only weakly related to R_S. No interaction effects between irrigation and fertilization were observed for R_S and microbial variables. Irrigation increased R_S, fine root mass and microbial biomass C. In contrast, fertilization increased R_H, microbial biomass C and microbial activity but reduced fine root biomass and had no influence on R_S. Predicted annual soil C efflux ranged from 8.8 to 10.7 Mg C ha⁻¹ year⁻¹ and was lower than net primary productivity (NPP) in all stands except the non-fertilized treatment. The influence of forest management on R_S was small or insignificant relative to biomass accumulation suggesting that NPP controls the transition between a carbon source and sink in rapidly growing pine systems.     

Aboveground biomass quantification and tree-level prediction models for the Brazilian subtropical Atlantic Forest

Forests are the largest biological reservoir of biomass and carbon on the planet. This fact turns them into the main tool to neutralise the CO₂ emitted by human activities. Despite such importance, the uncertainties associated with biomass estimates in forests, especially in (sub)tropical forests, are enormous. Facing this scenario, the objectives of this study were (1) to quantify through destructive sampling the aboveground biomass (AGB) of 105 trees of 47 species occurring in a secondary subtropical evergreen rainforest in Brazil; (2) to investigate the AGB distribution in different tree compartments; and (3) to fit tree-level models to improve biomass estimates for the referred forest type. The results revealed that most of the AGB was stored in the compartments stem and large branches (diameter ≥ 5 cm). There was an increase in the proportion of biomass – in relation to the total tree AGB (kg) – allocated in the large branches as tree diameter at breast height (DBH) increased; this pattern was not observed for the compartments stem, thin branches (diameter < 5 cm), and leaves. The compartments thin branches and leaves represented between 5.4% and 17.0%, and 1.3% and 2.9% of the total tree AGB, respectively. From the 10 fitted biomass models, the linearised power models yielded the smallest errors. The best performance model, which returned a mean bias of 1.7%, may be written as AGB = exp(?8.9807 + 2.1642·ln[DBH] + 0.5072·ln[h] + 0.9999·ln[ρ_bas]); Baskerville’s factor = 1.0175. If there are no (reliable) data on tree total height (h; m), the following model, which embedded the DBH and wood basic specific gravity (ρ_bas; kg m^?3), may be employed: AGB = exp(?9.0086 + 2.4606·ln[DBH] + 1.0895·ln[ρ_bas]); Baskerville’s factor = 1.0206.     

Goodness-of-fit analysis on wood properties data from six Brazilian tropical hardwoods

As part of a larger effort to develop design stresses for six hardwood species indigenous to tropical Brazil, a study was conducted to evaluate the relative goodness-of-fit of four distributions (normal, lognormal, Weibull, and S_B) that are used in wood related applications to the characterization of the modulus of elasticity (MOE) and modulus of rupture (MOR) data obtained from tests on lumber and clear wood specimens. Three criteria [maximum likelihood, Kimball, and Kolmogorov-Smirnov (K-S)] were used to evaluate the distributions over their entire domain. The K-S test was also employed at the lower tail of the distributions to evaluate goodness-of-fit at this crucial location for design stress development. The results showed that with respect to both MOR and MOE, the S_B distribution was as good or better than the other distributions. This was especially noticeable with the MOR data, since this data is often more skewed than MOE and the S_B is particularly well suited to describe positively and negatively skewed data. The lognormal and the Weibull were both found to be useful under certain circumstances; the normal distribution, due to its lack of ability to characterize anything but symmetrical distributions, was found to be of virtually no value in this application. Significant distinctions were found between the structure of MOR and MOE data sets obtained from the tropical and temperate zone species. For reasons believed to be related to gross and anatomical structure, more skewness was found in the two temperate zone species studied than in the six tropical species. As such, the S_B distribution, with its greater ability to quantify skewed data, performed overwhelmingly better than the other distributions. In describing the six tropical species, the advantage of the S_B distribution was less pronounced. Received 16 November 1998     

Goodness-of-fit analysis for lumber data

Summary Four different probability distributions were studied to evaluate their relative goodness-of-fit in describing the modulus of rupture (MOR) and modulus of elasticity (MOE) of populations of dimension lumber. The distributions under consideration were the normal, lognormal, Weibull and Johnson's S_B. The populations of lumber consisted of 96 data sets of various species groups, mechanical properties, sizes, structural grades and growth regions. The goodness-of-fit criteria selected in this study were the log likelihood, Kimball and Kolmogorov-Smirnov (K-S) tests. The K-S statistic was also calculated at the value of the random variable associated with the lower five percent exclusion limit of the empirical cumulative distribution. This value indicated the degree of goodness-of-fit at the lower tail of the distribution. The results indicated that the S_B distribution generally provided the best fit to the data. The maximum likelihood test overwhelmingly recommended the S_B distribution. The Kimball and Kolmogorov-Smirnov tests gave milder endorsements of the S_B distribution. No distribution proved to be superior to the others in modeling the lower five percent exclusion limit of the populations.The author would like to thank the Engineering Data Management (EDM) Inc. of Fort Collins, Colorado, for the use of their parameter evaluation software, STAtistical Data MANager     

Baumhöhenschätzung mit Hilfe der bivariaten Johnson’s SBB-Funktion

Zusammenfassung Die Verwendung der S_BB-Funktion (Johnson 1949) als Hilfsmittel zur Sch?tzung der Bestandesh?henstreuung wird erl?utert. Es wird ein Verfahren vorgestellt, mit dem Inventurinformationen auch bei ungleichen Anzahlen an BHD-H?hen-Wertepaaren vollst?ndig genutzt werden k?nnen. Da aus Bestandesinventuren h?ufig relativ wenige H?hen zur Parametrisierung zur Verfügung stehen, werden Simulationen des Verfahrens für unterschiedlich gro?e Stichprobenumf?nge und Auswahlvarianten an BHD-H?hen-Paaren für einen Beispielbestand berechnet. Die Ergebnisse werden auf der Basis der Abweichungen der generierten von den gemessenen H?hen und über mittlere relative Abweichungen der bedingten H?ufigkeitsverteilungen der einzelnen Simulationen von der Parametrisierung auf der Basis aller Wertepaare des Beispielbestandes beurteilt. Weiterhin werden die Ergebnisse von H?hensch?tzungen für den Gesamtbestand und das Teilkollektiv der Oberschichtb?ume verglichen. W?hrend die H?hensch?tzungen für die Oberschicht geringe Fehler- und Biaswerte aufweisen, treten für den zweischichtigen Gesamtbestand in Teilbereichen systematische über- und Untersch?tzungen auf.      

小陇山2种典型天然林空间结构参数分布特征

采用林分空间结构参数一元分布、二元分布、林分综合指数和距离分析方法,探讨小陇山林区2种典型天然林空间结构特征。结果显示:(1)油松天然林混交度为0.397,树种隔离程度较低,锐齿栎天然林混交度为0.797,混交良好,油松、锐齿栎天然林胸径大小比数分别为0.507、0.485,林分均处于中庸状态,角尺度分别为0.511、0.508,林木分布格局均属随机分布。(2)油松、锐齿栎天然林中相同混交程度或优劣程度的林木大多处于随机分布,相同混交程度或分布格局的林木处于不同优劣程度的林木大致相等。区别在于油松天然林中同一优劣程度或分布格局的林木大多与同种相邻,而锐齿栎天然林中同一优劣程度或分布格局林木大多处于强度和极强度混交。(3)油松、锐齿栎天然林林分空间结构指数(FSSI)分别为0.526、0.739,林分空间结构距离(FSSD)分别为0.788、0.576,锐齿栎林空间结构明显优于油松林。FSSI和FSSD具有极显著的线性关系,FSSD=-1.481 5×FSSI+1.625 7,R²=0.990 6(P < 0.01),二者在表述林分空间结构方面具有较强的一致性。研究表明:二元分布、林分空间结构指数和距离分别是从林木水平和样地水平研究林分空间结构较为有效的方法,可为小陇山林区林分微观结构分析和精细的结构调整提供新途径。     

Variation among poplar clones for growth and crown traits under field conditions at two sites of North-western India

We evaluated the growth and crown traits of 36 poplar clones at two distinct agro-climatic regions of Punjab (Ludhiana and Bathinda) in northwestern India, following randomized block design with three replications and plot size of four trees. Significant differences among clones (p<0.001) were observed for diameter at breast height (DBH), tree height, volume, crown width and number of branches under both the site conditions. Clones ’G-3’, ’25-N’ and ’41-N’ at Ludhiana and ’G-3’, ’RD-01’ and ’S 7 C 8 ’ at Bathinda were found to be superior for volume production. All growth and crown traits registered significantly higher values at Ludhiana in comparison to those at Bathinda. Clone × site interaction was also significant (p<0.001). For volume, clones ’L-62/84’, ’113520’, ’25-N’ and ’S 4 C 2 ’ witnessed huge fluctuations in ranking between sites. The correlations between growth traits were positive and highly significant (p<0.001) at both sites. The clonal mean heritability was moderate for DBH and volume both at Ludhiana (0.61 0.66) and Bathinda (0.61 0.62). Across sites, the genetic advance was the highest for volume (49.76%) and the lowest (6.50%) in case of height.     

Comparison of beta,Johnson’s SB,Weibull and truncated Weibull functions for modeling the diameter distribution of forest stands in Catalonia (north-east of Spain)

The purpose of this study was to compare the beta, Johnson SB, Weibull and truncated Weibull functions in describing the diameter distributions of forest stands in Catalonia. The data consisted of permanent sample plots from the Spanish National Forest Inventory in Catalonia. The empirical data represent left-truncated distributions, as the smallest diameter measured in the field was 7.5 cm. A total of 1,242 plots were used to fit the functions and analyze their performance. The distribution functions were fitted to the diameter distributions of the number of stems (DD_N) and stand basal area (DD_G). The performance of the candidate functions was compared by means of their bias and RMSE for different diameter sums measuring the difference between the empirical and fitted distributions. The leftmost part (from 0 to 7.5 cm) of the non-truncated functions was ignored in this analysis. Sensitivity analyses were conducted to check whether the results depended on the number of trees measured in the stand, or the main species of the stand. The truncated Weibull function for the diameter distribution of stand basal area appeared to be in all cases the most accurate and consistent function. Generally, functions describing the distribution of stand basal area performed better than functions that described the distribution of the number of trees. Of the basal area distributions, beta and Johnson’s SB were the second best and nearly equally good with each other. The order of precision of the tested functions was: truncated Weibull for DD_G, truncated Weibull for DD_N, Johnson’s SB for DD_G, beta for DD_G, beta for DD_N and Weibull for DD_G, Weibull for DD_N, and Johnson’s SB for DD_N.     

HPLC-based activity profiling of Angelica pubescens roots for new positive GABAA receptor modulators in Xenopus oocytes

A petroleum ether extract of the traditional Chinese herbal drug Duhuo (roots of Angelica pubescens Maxim. f. biserrata Shan et Yuan), showed significant activity in a functional two-microelectrode voltage clamp assay with Xenopus oocytes which expressed recombinant γ-aminobutyric acid type A (GABA_A) receptors of the subtype α₁β₂γ_2S. HPLC-based activity profiling of the active extract revealed six compounds responsible for the GABA_A receptor modulating activity. They were identified by microprobe NMR and high resolution mass spectrometry as columbianetin acetate (1), imperatorin (3), cnidilin (4), osthol (5), and columbianedin (6). In concentration-dependent experiments, osthol and cnidilin showed the highest potentiation of the GABA induced chloride current (273.6% ± 39.4% and 204.5% ± 33.2%, respectively at 300 μM). Bisabolangelone (2) only showed minor activity at the GABA_A receptor. The example demonstrates that HPLC-based activity profiling is a simple and efficient method to rapidly identify GABA_A receptor modulators in a bioactive plant extract.     

Allomorphs of native crystalline cellulose I evaluated by two equatoriald-spacings

The aim of this study was to develop a facile method for categorizing native celluloses as the algal-bacterial type or the cotton-ramie type and for estimating the I_α/I_β (triclinic/monoclinic) ratio of the cellulose samples. We investigated various native celluloses by X-ray diffractometry; and discriminant analysis was carried out using two equatoriald-spacings: 0.59–0.62 nm (d ₁) and 0.52–0.55 nm (d ₂). All of the samples were classified into the two groups without error. The function used to discriminate between the two groups is represented as:Z=1693d₁ — 902d ₂ — 549, whereZ>0 indicates the algal-bacterial (I_α-rich) type andZ<0 indicates the cotton-ramie (I_β-dominant) type. Another X-ray diffraction study of hydrothermally treatedCladophora cellulose revealed the relation between thed-spacings (d ₁,d ₂) and the I_α/I_β ratio. A calibrating equation by which the I_α/I_β ratio was estimated from the two parameters,d ₁ andd ₂, was then prepared. In the case of relatively highly crystalline native celluloses, it was found that the I_α/I_β ratio is easily determined by applying the two parameters in the equation.     

The diffusion, size and location of added silver grains in the cell walls of Swedish pine, Pinus sylvestris

The size and location of silver particles in K-glycerate/AgNO₃ impregnated Swedish pine, green wood as well as high temperature dried, have been studied using TEM micrographs. The diameter of the silver particles was found to be 2–20 nm in the impregnated green wood and as large as 1000 nm (major axis) for the ellipsoid-shaped silver clusters in the impregnated dried wood. Studying the projected area of the silver particles in impregnated green wood indicated that there are a lot of particles (40%) in the compound middle lamella with fewer particles in the S₂ (6–8%), S₁ (4%) and S₃ (2%) layers. The average distance between the silver particles, 50 nm (S₂-layer), in impregnated green wood shows that the impregnant is distributed in the cell wall at the microfibrilar level. Experimental results show that the fastest diffusion path into the cell wall is from the lumen over the pit membrane through the compound middle lamella and not from the lumen through the secondary wall layer S₃. Received 11 January 1998