Relationships between tree parameters above ground and the biomass of the coarse root system were examined in six mixed spruce-beech stands in the Soiling Mountain region in northwest Germany. The ...selected stands were located on comparable sites and covered an age range of 44 to 114 years. Coarse roots (d ≥ 2 mm) of 42 spruce and 27 beech trees were sampled by excavating the entire root system. A linear model with logarithmic transformation of the variables was developed to describe the relationship between the coarse root biomass (CRB, dry weight) and the corresponding tree diameter at breast height (DBH). The coefficients of determination (R²) attained values between 0.92 for spruce and 0.94 for beech; the logarithmic standard deviation values were between 0.29 and 0.43. A significantly different effect of tree species on the model estimates could not be detected by an analysis of covariance (ANCOVA). For spruce, the derived relationships were similar to those reported in previous studies, but not for beech. Biomass partitioning in the tree compartments above and below ground differs significantly between spruce (coarse root/shoot ratio 0.16 ± 0.06) and beech (coarse root/shoot ratio 0.10 ± 0.03) in the mixed stands. These results are similar to those given in other studies involving pure spruce and beech stands on comparable sites in the region, although the ratios of pure stands in other regions growing under different site conditions are somewhat higher. Comparing trees of the same DBH classes, root/shoot ratios of spruce are 1.2 to 3 times higher than those of beech. Dominant spruce trees (DBH > 60 cm) attained the highest ratios, suppressed beech trees (DBH < 10 cm) the lowest. Site conditions of varying climate and soils and interspecific tree competition are likely to affect root/shoot ratio and DBH-cozrse root biomass relationships. The greater variability in beech compared with spruce indicates a high 'plasticity' and adaptability of beech carbon allocation. Thus, the derived equations are useful for biomass estimates of coarse roots involving trees of different ages in mixed stands of spruce and beech in the Soiling Mountains. However, application of these relationships to stands in other regions would need further testing.
•In India, some LTRS are in good condition while some degraded; maintenance is poor.•Traditional sampling design must be improved as TCP contain limited information.•The long-term FOS Data ...effectively complement forest inventory and monitoring.•FOS provides empirical basis for understanding ecosystem structure and dynamics.•FOS network provide coverage of extreme sites and densities essential for modelling.
Long term forest research sites in India, going by different names including Linear Tree Increment Plots, Linear Increment Plots, Linear Sample Plots and Permanent Preservation Plots, cover diverse plant communities and environmental conditions. Presently, some of these long-term observational studies are functional, some are disturbed and others have almost been lost. The accumulated data will become increasingly important in the context of environmental modelling and climate change, especially if the plots and data can be maintained and/or revived. This contribution presents the history and current state of forest research plots in India, including details of locations and re-measurements. We provide a brief introduction of the National Forest Inventory (NFI), Preservation Plots in natural forests, the 50-ha Mudumalai Forest Dynamics Plot as part of the Centre for Tropical Forest Science and Smithsonian Institution Global Earth Observatories network (CTFS–SIGEO), and research plots established in plantations for tree growth studies and modelling. We also present some methodological details including assessment and analysis for two types of observational studies, the Tree Count Plots (TCP) and Tree Re-measurement Plots (TRP). Arguments are presented in favour of enumeration and analysis methods which are consistent with current approaches in forest ecological research.
The study presents an analysis of the diameter distributions of nine virgin beech forests (
Fagus sylvatica) in south-eastern Europe. Data were collected from published and unpublished sources. We ...included predominantly full calliperings of coherent areas between 3.6 and 13.0
ha of size. The objective of the study was to compare and characterize the curve forms and to test systematically which mathematical function provides a better fit: the negative exponential function, third or seventh degree Weibull functions. The parameters were estimated applying the maximum likelihood method. To evaluate the goodness of fit, the absolute discrepancy was used. The residuals were examined with respect to systematic deviation.
The nine virgin forests displayed a great variety of structures, only four out of 36 possible pairs of diameter distributions were found to be from the same population. The negative exponential model produced a good fit for four of the nine empirical distributions. However, the analysis of the residuals produced by the models exhibited systematic errors. Both the negative exponential and the third degree Weibull function underpredict to some extent the number of stems in the midsize diameter range in all nine stands. The higher number of trees frequently found in the midsize range of the empirical distributions as compared to the models indicates a common trend towards a rotated sigmoid diameter distribution. For some stands even a tendency towards two peaks in the distribution can be found. These results reveal that the reverse J-shaped curve form is not the only applicable model for describing diameter distributions in virgin beech forests. The systematic nature of the deviations from the negative exponential curve leads us to conclude that we might have found a general trend typical for virgin beech forests in south-eastern Europe.
This article sets out to investigate alcohol and substance use (ASU) among adolescents living with HIV (ALWH) in the sub-Saharan African setting of Uganda. A cross-sectional analysis of the records ...of 479 adolescents (aged between 12and 17 years) attending the study, "Mental health among HIV infected CHildren and Adolescents in KAmpala and Masaka, Uganda (the CHAKA study)" was undertaken. ASU was assessed through both youth self-report and caregiver report using the Diagnostic and Statistical Manual of Mental Disorders-5 referenced instruments, the Youth Inventory-4R and the Child and Adolescent Symptom Inventory-5 (CASI-5). Rates and association with potential risk and outcome factors were investigated using logistic regression models. The rate of ASU was 29/484 (5.9%) with the most frequently reported ASU being alcohol 22/484 (4.3%) and marijuana 10/484 (2.1%). Functional impairment secondary to ASU was reported by 10/484 (2.1%) of the youth. ASU was significantly associated with urban residence, caregiver psychological distress and the psychiatric diagnosis of post-traumatic stress disorder. On associations with negative outcomes, ASU was significantly associated with only "ever had sex". Health care for ALWH in sub-Saharan Africa should include ASU prevention and management strategies.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Understanding how and why species abundance distributions (SADs) vary with sampling scale has been a long-standing issue in ecology. By fitting various SAD models with observations collected in three ...large forest field plots, the objective of this study is to explore how the shape of SADs and the predictive ability of SAD models vary with sampling scales. Based on a large dataset collected in the Changbaishan, Jiaohe and Liangshui forests in northeastern China, observed SADs were compared with SADs estimated using five different models (log-normal, broken stick, Zipf, niche preemption and neutral model) at four sampling scales (10 × 10 m, 30 × 30 m, 60 × 60 m and 90 × 90 m). The results show that the studied SADs are scale dependent. Niche-based models provided a better fit at small sample sizes, the predictive ability decreasing with increasing sampling scale. The neutral model performed better at large sample sizes, the predictive ability increasing with increasing sampling scale. We identify the models that provided the best fit to observed species abundance distributions across spatial scales, and conclude that there is not one best SAD model for all spatial scales. Future studies should consider the scale effects on the species abundance distribution.
In this opinion paper we investigate the effects of forest management on animal and plant biodiversity by comparing protected areas with intensively and extensively managed forests in Germany and in ...Romania. We want to know the extent to which differences in diversity of Romanian compared to German forests are based on management. The number of tree species was not different in protected and managed forests ranging between 1.8 and 2.6 species per plot in Germany and 1.3 and 4.0 in Romania. Also herbaceous species were independent of management, ranging between 13 species per plot in protected forests of Romania and 38 species per plot in German coniferous forest. Coarse woody debris was generally low, also in protected forests (14 to 39 m3 ha−1). The main difference between Romania and Germany was the volume of standing dead trees (9 to 28 m3 ha−1 for Romania), which resulted in larger numbers of forest relict saproxylic beetles independent of management. Large predators (wolves, bears and lynxes) are only found in regions with low human intervention. Thus, we identified a "cut and leave" type of management in Romania, in which clear-felling of forest are followed by long periods of no human intervention. Forests managed in the "cut and leave" mode contained the highest diversity, due to a natural succession of plant species and due to habitat continuity for animals. In Germany intensive management eliminates poorly formed tree individual and species of low market value during stand development. Forest protection does not ensure the maintenance of more light demanding key species of earlier stages of succession unless competition by shade-tolerant competitors is reduced through disturbances. We compare the economics of intensive and extensive management. The "cut and leave" mode delivers less wood to the wood market, but saves expenses of tending, thinning and administration. Thus the net income could be quite similar to intensive management at a higher level of biodiversity. Our analysis suggests that forest protection per se does not yet ensure the maintenance of species. Clear-felling followed by natural succession may even be superior to the protection of old growth forests, regarding biodiversity. Further research is needed to substantiate this hypothesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Ernst Assmann belonged to the most influential German forest scientists in the twentieth century. His systemic and scale-overarching scientific approach toward forest dynamics triggered a wealth of ...research lines that continue up to the present day. In this article, we recall his scientific vita, his most important discoveries and his scientific legacy. In honor of this outstanding researcher, the European Journal of Forest Research initiates the series of
Ernst Assmann Reviews on Production Ecology and Quantitative Silviculture
.
A generalized height–diameter (
h–
d) model based on Schnute's function was developed for radiata pine (
Pinus radiata D. Don) plantations in Galicia (northwestern Spain). The study involved the ...estimation of fixed and random parameters by mixed-model techniques. The hierarchical structure of the data set, trees within plots, justifies the application of mixed-effects modelling. Techniques for calibrating the generalized height–diameter model for a particular plot of interest were also applied. For the experimental data analyzed, calibration can be used to obtain
h–
d relationships tailored to individual plots after measuring the height of only the three smallest trees in a plot. The main reason for the high predictive ability using this subsample of trees is that the dominant height of each plot was already considered as a fixed-effect in the height–diameter model formulation; therefore, heights corresponding to the largest trees did not provide much more additional information for calibrations. The model also included an unstructured random component to mimic the observed natural variability in heights within diameter classes for the same plot. This is an important aspect because the model will be applied to fill in the missing height measurements, subsequently used for assessing variables (e.g., volume, biomass, etc.) that depend on the estimated heights.
Using permanent sample-plot data, selected tree height and diameter functions were evaluated for their predictive abilities for major tree species in complex (multiple age, size and species cohort) ...stands of interior British Columbia (BC), Canada. Two sets of models were evaluated. The first set included five models for estimating height as a function of individual tree diameter, the second set also included five models for estimating height as a function of individual tree diameter and other stand-level attributes. The inclusion of the BAL index (which simultaneously indicates the relative position of a tree and stand density) into the base height-diameter models increased the accuracy of prediction for all species. On average, by including stand level attributes, root mean square values were reduced by 30.0 cm. Based on the residual plots and fit statistics, these models can be recommended for estimating tree heights for major tree species in complex stands of interior BC. The model coefficients are documented for future use.PUBLICATION ABSTRACT
The geographical patterns of tree species richness in forest communities have been studied widely, but little is known about the geographical variation of the estimated species richness and minimum ...areas using species-area curves. A differential technique based on the species-area relationships (SAR) was developed for estimating the minimum area (Amin) capturing 60-80% of the species in each plot, which is an important characteristic of a forest community. The relationship between estimated species richness (ESR) from the SAR and the corresponding minimum area is described by the linear model ESR = 0.0051×Amin (R2 = 0.98, p < 0.0001). Both the ESR and the minimum area exhibit similar geographical variations with a significant increase along altitudinal and a decrease along latitudinal gradients. The spatial variations of the ESR were partitioned into three geographical components and their combined effects. Altitude accounted for 40% and 45% of the total variation in the ESR and the minimum area, respectively. While latitude accounted for 69% and 61% of the total variation in the ESR and the minimum area, respectively. Thus, latitude is the main determinant which influences the geographical variation of the ESR. As far as we know, this study presents the first report of the geographical patterns of the minimum area in temperate forests.
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