Data from five studies on the relationships between dendrometric measurements and leaf area of Eucalyptus
globulus Labill. plantations were pooled and analyzed to develop regression models for the estimation of leaf area of
individual trees. The data, collected at two sites in west-central and southwestern Portugal, varied in age from 2 to 19 years
and in plant density from 481 to 1560 trees/ha and included both first and second rotation coppice stands. A total of
29 nonlinear regression models were tested and ranked with a multicriteria evaluation (MCE) procedure, based on
goodness-of-fit statistics, predictive ability statistics, and collinearity diagnostics. The best models were validated using an
independent data set. The final model selection was based on comparisons of prediction residuals data, statistical tests, and
silvicultural and physiological considerations. One model is proposed as adequate for leaf area estimation of E. globulus
plantation trees. This model contains four parameters and independent variables that quantify stem diameter, crown size, and
The life-cycle of Callibia diana Stål is described and linear and geometric morphometrics are used for studying allometrics and shape changes throughout this neotropical mantid species' life-cycle. Significant changes were expected in the allometry and shape of the raptorial leg and abdomen, given the importance of hunting and reproduction. The allometric slopes were obtained by using total length as the independent variable. Geometric morphometrics of landmarks were used for frontal femur and tibia. Hunting and reproduction-related structures had the steepest slopes and positive allometries. Negative growth of both disc width and head width found in the last moulting event may be a consequence of prothoracic muscle growth which is responsible for predatory strike strength. The tibial claw and femur of the raptorial leg become larger, while their spines become more orthogonal to the longitudinal axes which may facilitate prey retention. These changes in mantid shape throughout ontogeny were consistent and suggested the resource allocation and development programming of the body that improved reaching distance and prey retention.
Barnes and Roderick [Barnes, B., Roderick, M.L., 2004. An ecological framework linking scales across space and time based on self-thinning. Theoret. Popul. Biol. 66, 113-128] developed a generic ecological framework for scaling from individuals to ecosyst
A method of estimating trunk and branch volumes of single trees is presented that uses a combination of elementary field measurements, terrestrial photography, image rectification and on-screen digitising using commercial software packages and automated volume calculation. The method is applicable to a variety of different sized trees in situations where the trunks are clearly visible. Results for taper measurement and wood volume calculation are presented for Eucalyptus regnans F. von Muell., Sequoiadendron giganteum (Lindley) Buchholz and Quercus robur L. Branch allometrics are provided for E. regnans. The largest errors arose from field observations. If the trees are asymmetrical in cross-section (e.g. due to irregular buttressing or forked stems), or if there is no vantage point perpendicular to the direction of lean, then photographs from more than one side are recommended. Accuracy and precision of geometric reproduction by the image rectification process, and the volume calculation, were tested using mathematically generated tree components. The errors in the branch volumes of the virtual tree showed complex trends due to interacting factors. Volumes were underestimated by an average 0.5% for stems and 4% for branches. Due to the area deficit resulting from non-circular cross-sections of the buttress...
Scaling up from measurements made at small spatial and short temporal scales is a central challenge in the ecological and related sciences, where predictions at larger scales and over long time periods are required. It involves two quite distinct aspects: a formulation of a theoretical framework for calculating space-time averages, and an acquisition of data to support that framework. In this paper, we address the theoretical part of the question, and although our primary motivation was an understanding of carbon accounting our formulation is more general. To that end, we adopt a dynamical systems approach, and incorporate a new dynamical formulation of self-thinning. We show how to calculate rates of change for total (and average) plant dry mass, volume, and carbon, in terms of the properties of the individual plants. The results emphasize how local scale statistics (such as, variation in the size of individuals) lead to nonlinear variation at larger scales. Further, we describe how regular and stochastic disturbance can be readily incorporated into this framework. It is shown that stochastic disturbance at patch-scales, results in (to first approximation) regular disturbance at ecosystem scales, and hence can be formulated as such. We conclude that a dynamical formulation of self-thinning can be used as a generic framework for scaling ecological processes in space and time.
Barnes and Roderick developed a generic, theoretical framework for vegetation modeling across scales. Inclusion of a self-thinning mechanism connects the individual to the larger-scale population and, being based on the conservation of mass, all mass flux processes are integral to the formulation. Significantly, disturbance (both regular and stochastic) and its impact at larger scales are included in the formulation. The purpose of this paper is to illustrate how this model can be used to predict patch and ecosystem dry mass, and consequently system carbon. Examples from pine plantations and mixed forests are considered, with these applications requiring estimates of system carrying capacity and the growth rates of individual plants. The results indicate that the model is relatively simple and straightforward to apply, and its predictions compare well with the data. A significant feature of this approach is that the impact of local scale data on the dynamics of larger patch and ecosystem scales can be determined explicitly, as we show by example. Further, the general formulation has an analytic solution based on characteristics of the individual, facilitating practical and predictive application.
Sex and age differential allometrics and growth in Sphaeroma serratum (Crustacea, Isopoda) from Guanabara Bay (Brazil); Alometria e crescimento sexual e etàriamente diferenciados em Sphaeroma serratum (Crustaceae, Isopoda) da baía da Guanabara (Brasil) JARBAS DE MESQUITA NETO