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Little is known about sustainable forest management and tree growth in the Amazon forest. Reliable growth data from trees are very important in the context of forest management. Tree-characteristics such as architecture and competition are associated with diameter growth. Previous studies analyzing tree growth have indicated that these variables can describe these effects for temperate and boreal forests. However, the role of these effects for the growth of tropical trees needs to be enhanced for forest management practices. Here, we reconstructed the periodic annual basal area increment ( BAI i cm 2 yr −1 ) of four long-lived timber species from the Amazon forest of Brazil: (i) Cedrela odorata, (ii) Amburana cearensis, (iii) Copaifera pauper and (iv) Swietenia macrophylla to investigate the growth development. The study focuses on (i) drivers important for individual tree growth, (ii) calibration of an individual tree basal area increment model for each of the four species, and (iii) assessing the practical implementation of our findings for enhancing sustainable forest management of these four tree species in the Amazon rainforest. The results exhibit a significant relationship between increasing basal area increment versus increasing crown length and decreasing competition expressed by Hegyi’s index. Trees sampled in densities greater than 25 m 2 ha −1 had their BAI % significantly reduced. For Cedrela an additional negative impact on basal area increment from liana load is evident. Our findings reinforce the importance of release trees to obtain better crown exposure.

Intensive forest management is known to influence soil structure and composition. Homogenous age class forests managed in a clear cut system reduce soil carbon and nutrients. Continuous cover forests (including plenter/single tree selection forests) on the other hand are considered to be a sustainable alternative, but little is known about their influence on soil carbon and soil nitrogen stocks. In this study, we investigated the recovery of soil carbon and nitrogen stocks after converting Norway spruce dominated age class forests (AC) into single tree selection/plenter forests (PL) at the Koralpe in the Austrian province of Styria. These forests originated from previous age class forests and the PL evolved after a decision from the early 1960s to change management from an age class system to a plenter system. Ten pairs of each a typical age class Norway spruce forest and a plenter forest adjacent to one another were obtained. The two stands of a pair are characterised by the same site conditions, and had the same stand history prior to the transition of one of the two stands. Differences in the stand and soil parameters by management regime are apparent. On the PL sites mineral soil in 0–20 cm depth contains 9 Mg C ha −1 or 11% more carbon and 0.4 Mg N ha −1 or 11% more nitrogen compared to the AC sites. Differences in total soil carbon (litter plus mineral soil) are not significant, whereas higher total soil nitrogen at PL are evident. These results suggest that soil conditions responded to changes in forest management practices.

Biogeochemical mechanistic models (BGC models) are used to model the carbon balance of forest ecosystems. Since European forests are managed intensively, a crucial part of carbon modelling is integrating management and thinning routines in the modelling process. In this study, forest inventory data are used to derive information concerning forest management practice. Based on this, a harvesting model is calibrated for simulating the ‘business as usual’ management that can be used in large-scale BGC models. Our approach is based on data from the Austrian National Forest Inventory. The model comprises two sub-models: (1) a logistic model to assess the probability of an inventory point to be thinned and (2) a non-parametric model based on empirical probability density maps to assess the thinning intensity. Since BGC models operate on the stand level, only stand level parameters are integrated in the model such as standing timber carbon, site quality, cover type, elevation and age. A comparison of the predicted and observed proportion of thinned points and the thinning intensity suggests that the model is able to correctly mimic the management regime derived from the inventory data. No systematic trends in the results are evident. Using this thinning model in combination with a mechanistic model will enable assessment of the overall carbon stored in managed forest ecosystems, especially in large-scale modelling applications.

Large scale forest productivity estimates are of increasing interest as more demands are made on forest resources. In principle three different methods are currently available: (i) forest growth data from forest research plots and/or forest inventory sampling points based on repeated tree observations, (ii) flux tower observations which record the gas exchange of the plant atmosphere interactions for a given vegetation type, and (iii) remotely sensed data for a continuous cover of net primary productivity estimates. In this paper we focus on the conceptual challenge in comparing “space based” moderate resolution imaging spectroradiometer (MODIS) satellite driven net primary production (NPP) vs. terrestrial “ground based” productivity estimates using forest increment data from 151 long term research plots with a well documented management history. The Austrian biomass functions are applied to derive ground based NPP estimates based on repeated tree observations from the plots. In addition we use BIOME-BGC as a diagnostic tool for exploring conceptual constraints among the two methods. The results of the study can be summarized as follows: (i) MODIS satellite driven annual NPP estimates provide a continuous productivity estimate across Austria and no significant differences between different daily climate input data sets were evident. (ii) MODIS NPP predictions provide forest productivity estimates of fully stocked forests with a complete crown cover. This is confirmed by the results of spin-up runs of the BIOME-BGC model. (iii) Terrestrial driven NPP predictions using the Austrian biomass functions compared well with MODIS driven estimates after addressing stand density effects of the forest plot data. The influence of stand density were known to be an integral component in reconciling “space based” satellite vs. “ground based” derived forest productivity estimates. After addressing stand density, computed forest productivity estimates compared well with MODIS-based estimates. This suggests that combining both methods will enhance our ability to generate forest productivity assessments across large forest areas.

Large-scale ecosystem models are designed to reproduce and quantify ecosystem processes. Based on plant functions or species-specific parameter sets, the energy, carbon, nitrogen and water cycles of different ecosystems are assessed. These models have been proven to be important tools to investigate ecosystem fluxes as they are derived by plant, site and environmental factors. The general model approach assumes uniform and fully stocked forests but since most European forests are managed (e.g., thinned) it is essential to understand the limits and precision of such models when applied to managed forest ecosystems. The purpose of this study is to investigate and incorporate common forest management practices within the large-scale ecosystem model Biome-BGC. Using “Monte-Carlo” simulations we analyze the theoretical response to current model settings assuming steadily decreasing changes in stand density. Results of the MC simulations as well as the comparison with measured data suggest that the resulting predictions will be biased. Using long-term experimental plots of Norway spruce ( Picea abies L. Karst.) and common beech ( Fagus sylvatica L.) forests with a well-documented thinning history, we propose a thinning subroutine, which addresses the changes in allocation patterns after stand density changes. Validation tests of improved model structure across different long-term experimental sites in Central Europe revealed unbiased and consistent simulation results.

During the last centuries forest management has changed the structure and species composition of central European forests. One option to assess forest management and how management impacts may affect forest development over time is the use of biogeochemical ecosystem simulation models. They integrate key ecosystem processes and have proven to be an appropriate diagnostic tool. If we consider that in the past, forest management has strongly affected the species distribution and the structure of central European forests, existing biogeochemical models need to integrate species-specific parameters so that they can adequately address forest management practices such as species changes, stand density etc. The purpose of this paper is to introduce species-specific parameters for one such model, Biome-BGC, for the following tree species as observed in central European forests: Fagus sylvatica, Quercus robur/petraea, Larix decidua, Pinus sylvestris, Pinus cembra as well as two sets of parameters for Picea abies growing at low and high elevations. We first evaluate and test model results obtained with parameters from the literature and single research plots. This evaluation procedure gives our final species-specific parameters that are then used in the model. Next we validate the quality of the model predictions using these parameters versus field observations covering the growing range of a given species by comparing standing tree volume, volume increment, soil carbon and soil nitrogen on 145 independent plots. Our results demonstrate that the species-specific parameters yielded consistent and unbiased predictions.

In Europe, fast growing tree species such as Norway spruce and Scots pine were promoted in large areas typically covered with broadleaf or mixed species stands to increase commercial timber growth. Recent research suggests that such secondary coniferous stands may have an increased susceptibility to environmental stress factors because of soil nutrient depletion as well as retarded litter decomposition. One option to increase the resilience of such stands is to reintroduce broadleaf trees because one species may directly benefit from the presence of another. A method to assess such effects and how their impact may change over time is the adaptation of mechanistic models. Such models integrate the main biogeochemical and physiological processes and are specifically designed to describe the interaction between plants and the environment. The purpose of this study is to enhance the ecophysiological representation of single tree species within an existing mechanistic model, a pre-condition for assessing forest ecosystem restoration scenarios. We changed ecophysiological constants using published literature related to Norway spruce and common beech for a wide range of central European forests and evaluated model predictions using observations on stand transpiration, seasonal water balance, leaf area index, photoassimilation, tree volume, tree ring size, and soil and litter carbon and nitrogen content. A model validation, using an independent data set on tree volume, soil carbon and nitrogen content from a total 44 spruce and beech stands across the northern part of the Austrian Alps, exhibited no bias between model predictions and field observations.

Using 30 years of climate records from 20 weather stations, we investigate the magnitude of temperature and precipitation change, and change in the length of the growing season between 1961 and 1990. Special attention is paid to the period between 1981 and 1990, because recent research suggests that, during this time span, forest productivity may have increased in the northern latitudes. In order to understand the importance of changes in climate on forest growth, we use the ecosystem model FOREST-BGC as a diagnostic tool to predict the annual net primary production (NPP). The results of our study indicate: no change in precipitation between 1961 and 1990; a significant (α = 0.05) increase in mean annual temperature of 0.72°C, mean annual minimum temperature (0.80°C), winter temperature (2.36°C) as well as an increase in the length of the temperature-controlled growing season by 11 days, resulting in a significant increase in diameter increment obtained from 1179 cores of Norway spruce across Austria. The trends in NPP are consistent with observed increment rates validating the use of biogeochemical modeling as a diagnostic tool to search for possible causes on changing environmental conditions.

The recruitment of trees following the death or cutting of an overstory tree is crucial for simulation models to achieve a consistent simulation output. To enhance the prediction of ingrowth uneven-aged mixed species stands, we developed a height-growth model for juvenile trees (≤ 1.3 m). The model predicts the actual periodical 5-year height increment by adjusting the corresponding potential height increment using: (1) the competition of the remaining overstory, (2) the intra-and interspecies competition among the regeneration itself, and (3) a modifier for the edge effected incidence of light. Data for this study came from 240 sample plots located in uneven-aged mixed species stands consisting of Norway spruce ( Picea abies L. Karst), fir ( Abies alba Mill.), and common beech ( Fagus silvatica L.). The number of trees on each plot was recorded by species and height class. One typical tree was selected to determine the tree height and the height increment of the past five years of growth for each species and height class. The sample consists of 265 spruce, 139 fir, and 286 beech trees. Additionally, we measured the distance to the stand edge along with the maximum possible angle of incidence for sunlight. For all trees in the overstory (height > 1.3 m), we recorded the diameter at breast height, the tree height, and the height to the crown base. The results demonstrate two things: first, the two competition measures and the modifier for the edge effected incidence of light were important for spruce and beech regeneration, while the competition among the regeneration for fir had no significant impact. Second, except for the smallest height class of fir and beech (≤ 20 cm), which showed a slight tendency to overestimate 5-year height increment rates, the resulting models produce unbiased predictions.

The purpose of the study is to investigate crown width, breast height diameter, height to live crown base, and taper rates of trees which were unaffected by inter tree competition throughout their life. Such open-grown trees represent the empirical maximum tree dimensions which have been used for developing management guidelines, modelling competition and crown closure. Using 435 open-grown trees including 11 different tree species from an Austria-wide open-grown tree study, equations were developed for predicting: (1) the crown width, (2) the breast height diameter, (3) the height to live crown base, and (4) the taper rates of such open-grown trees. All developed relationships were tested for possible site variations. The results indicate that except for the breast height diameter-height relationship of stone pine and the taper rates of Norway spruce and larch, site influences can be neglected because they unduly complicate empirical assumptions for a small gain in predictability. Finally, the results of this study make it possible to determine maximum tree dimensions for all tree species in Austria.

A crown ratio model for individual trees is developed for all major tree species in Austria. The study is part of a comprehensive project developing a distance-independent single tree growth simulator for the full range of stand conditions in Austria. Data were obtained from the Austrian National Forest Inventory and consist of more than 42 000 trees growing on over 5000 permanent plots measured during 1981 and 1985. Crown ratio was predicted using nonlinear regression with a logistic function. The argument of the logistic was a linear combination of tree size characteristics, stand density measures, and topographic site factors. The total variation explained by the model varied from 49% for larch to 17% for the ‘other broadleaf species’. The model explained 41% of the variation in crown ratio for the principal species, Norway spruce. The model explained less than a quarter of the variation for all the broadleaf species and for stone pine. The effect of the size variables is approximately equal in importance to the variables representing competition for the major species. The set of topographic site factors explained the least amount of variation, less than 10% in all cases. Because the height/diameter ratio, the most important size variable, can also be considered to be an integrator of past competition, the crown ratio model is dominated by competition measures. A validation test using independent data from permanent research plots for the main species (Norway spruce, white fir, Scots pine, and beech) demonstrated that the models appear to be well behaved and robust for both pure even-aged and mixed uneven-aged stand types in Austria. Analyses of the residuals from permanent research plots representing a wide variety of thinning treatments indicate that the effect of management seems to be adequately represented by the model.