Stand Biomass Research Articles

Allometry and biomass dynamics in temperate mixed and monospecific stands: Contrasting response of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.)

Mixed forests generally outperform monospecific forests in terms of productivity, stability, and resilience and are becoming increasingly important for sustainable forest management. However, accurate estimates of tree biomass allocation, as well as aboveground and component biomass in mixed forests, remain scarce. Our study addressed three different objectives to identify differences in biomass between mixed and monocultures and develop biomass models: (1) identification of biomass growth patterns in mixed and monoculture stands using analysis of covariance (ANCOVA), (2) investigation of the best fitting approach to modeling aboveground biomass using logarithmic regression and nonlinear mixed-effects models, and (3) fitting compartment biomass proportion models by Dirichlet regression, considering the additivity property. We analyzed 52 harvested trees from six plots within an experimental triplet in northern Spain, consisting of mixed and single-species stands of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.). Moreover, diameter at breast height and tree height were used as covariate variables to determine the most accurate and unbiased models. The research findings showed that (i) allometric patterns of individual-tree biomass in mixed stands significantly differed from those in monospecific stands for sessile oak, while those in Scots pine did not change; (ii) nonlinear mixed-effect models demonstrated a better fit – indicated by lower Furnival index values – than logarithmic regression models in predicting aboveground biomass; and (iii) the fitted biomass equations provided good performance and accurate estimates of biomass component proportions compared to those of existing models. Consequently, our results offer a better understanding of biomass and carbon storage within mixed and monoculture forests in the context of climate change.

Aboveground biomass estimation models for Tectona grandis Linn f. plantation in Nnamdi Azikiwe University, Awka, Nigeria

Tree biomass is considered a useful indicator of structural and functional attributes of forest ecosystems across a wide range of environmental conditions. The aboveground biomass refers to the living vegetation above the soil, including stem, stump, branches, bark, seeds, and foliage. Teak (Tectona grandis Linn f.) is a popular exotic tree species in Nigeria; it is widely grown in both large scale and small community woodlots. The objective of this study was to develop models for estimation of biomass content of Teak plantation in Nnamdi Azikiwe University, Awka, Nigeria for sustainable management. Data on the diameter at breast height (D) and total height (H) of all teak stands in the plantation were recorded. Non-destructive method using an existing equation was used to estimate the aboveground biomass (AGB) of the individual stands from stump diameter. The Data was subjected to descriptive statistics, bivariate correlation analysis and fitted to six (6) linear regression functions. A total of 295 trees were measured with mean AGB of 18.61 kg. Out of the AGB prediction models developed for the study area, the Semi Log 3 (B5) model had the best predictive ability; with the highest adjusted coefficient of determination (0.984) and the lowest standard error of estimate (0.308), and Akaike information criterion (-690.974). Model B5 (B=0.764+0.764D-0.105lnH) is therefore recommended for future inventory and management of the plantation.

Temporal Variations in Aboveground Biomass, Nutrient Content, and Ecological Stoichiometry in Young and Middle-Aged Stands of Chinese Fir Forests.

Understanding the ecological dynamics of forest ecosystems, particularly the influence of forest age structure on soil carbon (C), nitrogen (N), and phosphorus (P) content, is crucial for effective forest management and conservation. This study aimed to investigate the nutrient storage and ecological stoichiometry across different-aged stands of Chinese fir forests. Soil samples were collected from various depths (0-15 cm, 15-30 cm, and 30-45 cm) across four age groups of Chinese fir forests (8-year-old, 12-year-old, 20-year-old, and 25-year-old) in the Forest Farm, Pingjiang County, China. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) were measured, and their stoichiometries were calculated. The results showed that both individual tree biomass and stand biomass, along with SOC, TN, and TP content, increased with stand age, highlighting the significant importance of stand age on biomass production and nutrient accumulation in forests. Specifically, soil C and P contents significantly increased as the forest aged, while variation in N content was relatively minor. Soil C/N and C/P ratios exhibited variation corresponding to forest age, suggesting alterations in the ecological stoichiometry characteristics of the forests over time. These findings are crucial for understanding the dynamics of ecosystem functioning and nutrient cycling within Chinese fir forests and provide a solid scientific basis for the effective management and conservation of these vital forest ecosystems.

Stand Age and Climate Change Effects on Carbon Increments and Stock Dynamics

Carbon assimilation and wood production are influenced by environmental conditions and endogenous factors, such as species auto-ecology, age, and hierarchical position within the forest structure. Disentangling the intricate relationships between those factors is more pressing than ever due to climate change’s pressure. We employed the 3D-CMCC-FEM model to simulate undisturbed forests of different ages under four climate change (plus one no climate change) Representative Concentration Pathways (RCP) scenarios from five Earth system models. In this context, carbon stocks and increment were simulated via total carbon woody stocks and mean annual increment, which depends mainly on climate trends. We find greater differences among different age cohorts under the same scenario than among different climate scenarios under the same age class. Increasing temperature and changes in precipitation patterns led to a decline in above-ground biomass in spruce stands, especially in the older age classes. On the contrary, the results show that beech forests will maintain and even increase C-storage rates under most RCP scenarios. Scots pine forests show an intermediate behavior with a stable stock capacity over time and in different scenarios but with decreasing mean volume annual increment. These results confirm current observations worldwide that indicate a stronger climate-related decline in conifers forests than in broadleaves.

Assessment of the Biomass of Coniferous–Deciduous Forest by the Example of the Chashnikovo Training and Experimental Soil Ecological Center of Moscow State University

Abstract The aim of this work is to assess the contribution of the components of plant community—biomass and mortmass of tree stands, undergrowth, living ground cover, and forest litter—to its total organic matter pool. The study object is represented by a coniferous-deciduous forest located in the Solnechnogorsk city district of Moscow oblast and characterized by five permanent 50 × 50-m test plots laid in it. The greatest contribution to the total organic matter mass of the studied plant communities is made by perennial parts and mortmass of the forest stand (to 87% and 14%, respectively). The proportion of phytomass of deciduous trees in stand comprises from 32 to 98%, which is connected with the incomplete forest restoration succession. The contribution of forest litter does not exceed 3%. Low litter reserves (0.18–1.21 kg m–2) and the destructive type of all litters are not typical for spruce forests. The floristic composition and the ecological–coenotic structure of the living ground cover are typical for the subzone of coniferous-deciduous forests; and its contribution to the total productivity of forest biogeocenosis is insignificant. The spatial pattern of litter reserves and of the biomass of the living ground cover within the biogeocenoses is disturbed in comparison with typical spruce forests due to the high proportion of deciduous species in the forest stand. Their participation in the tree layer is typical for the final stage of formation of a secondary coniferous forest during succession and causes a slight increase in the intensity of the biological cycle, which is indicated in our case by a decrease in the reserves and a simpler structure of litters. Since the biomass and mortmass of tree stand contribute most to carbon sequestration by forest biogeocenoses, these components require a detailed assessment during monitoring surveys, the purpose of which is to evaluate carbon reserves of land ecosystems.

A New Formulation For Vegetation Induced Damping Under Waves And Currents Based On Their Standing Biomass

Estimation of the flow energy dissipation induced by an ecosystem that accounts for its characteristics (i.e. biomechanical properties, morphology, density) and the incident hydrodynamic conditions is crucial if ecosystem-based coastal protection measurements want to be implemented. Characterization of a vegetated ecosystem by measuring leaf traits, biomechanical properties of plants and the number of individuals per unit area involves a lot of effort and is case-specific. Previous studies have shown that wave height attenuation positively correlates with standing biomass (Maza et al., 2022) highlighting the crucial role played by this variable that can be used to estimate the ecosystem wave damping capacity without using calibration coefficients. In addition, this variable has been already characterized for many ecosystems and it can be estimated by aerial images (Doughty and Cavanaugh, 2019) and remote sensing techniques. However, this new approach has not been extended to conditions where waves and currents are simultaneously present. These conditions are very relevant to habitats like saltmarshes that are commonly affected by tidal currents or wave-induced currents flowing simultaneously with wind or swell waves. Then, to further explore this new approach based on the ecosystem standing biomass, a new set of experiments using real vegetation with contrasting morphology and biomechanical properties, and subjected to different combinations of waves and currents, is proposed. The obtained standing biomass-attenuation relationships will help to quantify the expected coastal protection provided by different vegetated ecosystems based on their standing biomass under the combined effect of waves and currents.

Возрастная динамика биомассы ольхи серой в древостоях Архангельской области

The assessment of forest productivity in forestry and forest ecology has a long tradition, but in recent decades there has been a paradigm shift: the target function of forestry, consisting in wood cultivation, has shifted towards the biosphere-stabilizing function and the assessment of biomass and carbon sequestration capacity of forests. Equations and tables for assessing biomass at the stand level have an advantage as they can be used to characterize both the biomass of individual stands and their totality, as well as (when combined with the state forest inventory data) the situations in the forests throughout the country. The complexity of the work on assessing biomass of trees and stands has prompted researchers to use the existing tables of growth progress when compiling the tables of biological productivity of the stands using the recursive method. For the conditions of the northern and middle taiga of the Arkhangelsk Region, there are no tables of growth progress for gray alder biomass. The aim of this research is to study the growth progress of gray alder biomass in the stands of the Arkhangelsk Region. A series of sample plots has been laid to assess the above-ground biomass of the trees of this species. Based on the actual data from 50 model trees from 30 sample plots, the allometric models of the dependence of biomass fractions on the stem volume have been developed. The obtained models have been combined with the tables of growth progress for gray alder by quality class and the table of biological productivity of the species for the conditions of the Arkhangelsk Region has been drawn up. The results have been compared with the data on the biological productivity of gray alder in Belarus, Lithuania and Latvia. It has been shown that the biomass of the mature stands of gray alder of the 1st and 2nd quality classes in the Arkhangelsk Region is 3–9 % less than in Belarus and Lithuania. For the stands of the third and fourth classes, this difference increases to 29–48 %. Such differences in the biomasses of the compared regions can be explained by different zonal site conditions.

Estimation and economic valuation of stands carbon in Tubokarto Community Forest, Pracimantoro District, Wonogiri Regency

Climate change mitigation efforts can be carried out by reducing CO2 gas emissions through the use of the forestry sector, which is expected to increase carbon sequestration. Community forests are composed of stands that have the potential to store carbon stocks so that they can play a role in achieving FOLU (Forest and Other Land Use) Net Sink 2030. This study aims to estimate biomass, carbon storage, and carbon economic value in Tubokarto community forest stands, Pracimantoro, Wonogiri. The method in this study used systematic sampling with random start to measure the DBH and tree height with a sampling intensity of 2% and made 50 sample plots measuring 0.04 ha. The carbon storage value is calculated based on the conversion of 47% of biomass estimated by allometric equations. The results showed that the community forest area of Tubokarto has a total biomass potential of 79.69 tons/ha, total carbon storage of 37.45 tons/ha, and a carbon economic value of Rp 14,605,787.19/ha or if multiplied by the total area of the community forest is Rp 1,329,126,634. The potential and economic valuation of carbon storage in community forests provides an opportunity to achieve sustainable development goals and reduction in carbon emissions.

Effect of Fertilization on Soil Fertility and Individual Stand Biomass in Strip Cut Moso Bamboo (Phyllostachys edulis) Forests

Strip cutting has emerged as a new, efficient, and mechanized bamboo forest management model. To shorten the recovery period in strip cutting management, improve bamboo resource quality, prevent soil degradation, and achieve sustainable management, we selected on-year pure Moso bamboo (Phyllostachys edulis) forests for an 8-meter-wide strip cut. Three fertilization methods were applied in a complete two-factor experiment, including spreading, cave, and bamboo stump fertilization, at three fertilization dosages of 600, 900, and 1200 kg/ha (N:P:K = 3.5:1:2). We investigated the effects of different fertilization treatments on the biomass of new bamboo shoots and soil fertility to provide a reference for identifying the optimal fertilization scheme. The results showed that fertilization treatment increased the individual stand biomass of new Moso bamboo shoots, with a decreasing trend in the proportion of branches and leaves and an increasing proportion of culms in biomass allocation. Fertilization treatment significantly increased the total nitrogen, phosphorus, and potassium and available phosphorus contents in the soil. Overall, fertilization at 900 kg/ha using the spreading method showed the best results in promoting individual plant biomass recovery (5% increase in culm proportion and 4.12 kg increase in biomass per plant) and restoring soil fertility (increase the contents of TN, TP, TK, and AP in the entire soil layer) after strip cutting Moso bamboo forests, which addresses these pertinent issues in the strip cut management model.

Stand biomass of Pinus sylvestris var. mongolica plantations benefits from high density monocultures in the boreal zone

Pinus sylvestris var. mongolica (P. sylvestris) plantations are extensively established in the boreal zone. Increasing stand biomass of these plantations can effectively enhance carbon stock, which is crucial for mitigating climate change. However, the current understanding of optimizing plantation strategies to maximize stand biomass is primarily derived from experiments in tropical and subtropical zones, which is difficult to extend to the boreal due to substantial climatic differences. Based on a comprehensive dataset from 1,076 sample plots of P. sylvestris plantations in the boreal zone of China, we evaluated the effects of tree species richness and stand density on tree height, diameter at breast height (DBH), and stand biomass to investigate the optimal plantation strategy. Furthermore, we examined how these effects changed with stand age and investigated their relative importance. We found that monocultures at a high stand density of 2,000–2,500 ​ha−1 were the optimal plantation strategy to maximize stand biomass (107.5 ​Mg·ha−1), and this held true at almost all stand ages. Unfortunately, this strategy resulted in low species richness and small individual trees (10.6 ​m height and 9.8 ​cm DBH), thus presenting a trade-off. In addition, as stand age increased, the effect of tree species richness on stand biomass shifted from positive to negative, but the effect of stand density was always positive. Overall, stand age had the greatest effect on stand biomass, followed by stand density and then tree species richness. Our findings reveal a distinct plantation strategy for optimizing stand biomass of P. sylvestris plantations in the boreal zone. More importantly, this study highlights that (1) maximizing stand biomass in the boreal zone may compromise tree species richness; (2) net effects of tree species richness on stand biomass are not always positive, as negative selection effects offset positive complementary effects.

РАСЧЕТ ЗАПАСА УГЛЕРОДА В БИОМАССЕ ДРЕВОСТОЕВ ЗАЩИТНЫХ ЛЕСНЫХ НАСАЖДЕНИЙ ПО ГРУППАМ ВОЗРАСТА ПРЕОБЛАДАЮЩИХ ПОРОД

Increasing the productivity and efficiency of protective forest plantations, taking into account their impact on solving the carbon neutrality of regions, is an urgent problem of modern agroforestry science. Based on the importance of solving the problem of reducing the volume of carbon dioxide, the purpose of the research is to assess the net ecosystem exchange of carbon dioxide in protective forest plantations (HLN) in the forest-steppe zone of the Volga upland. The paper uses methods for calculating the regional estimate of the carbon budget. The formation of a functionally targeted "carbon fiber" system of WLD facilities is carried out using a systematic priority-target method based on the basic forestry classification of protective forest plantations by age groups and breed composition. The distribution of protective forest stands by age group and breed composition made it possible to calculate the carbon reserve in the biomass of stands of protective forest stands. The calculation of the biomass of stands of coniferous and hardwoods made it possible to identify and establish for each age group the potential ability to effectively deposit carbon in the soil. Based on the carbon reserves established for each age structure and rock composition in the biomass pool of coniferous and hard-leaved stands by soil and climatic subdistricts, it becomes possible to regulate the carbon balance at the level of a separate region, a separate forestry enterprise. Taking into account the agroecological conditions of the sites – objects of protective afforestation, their main purpose, it is possible to use ZLN to include them in the long-term target "carbon" system of the region, with the development of measures for the regime of their use and increase their protective functions.. The accumulation of biomass of stands of different age groups depends on the soil and climatic disparity of slopes of different exposures and different agro-climatic subdistricts. Losses of carbon reserves in pools of protective forest plantations due to external influences as a result of economic activity or lack of care for these plantations reduce their protective effectiveness and productivity. Carbon reserves in the biomass of a stand of coniferous and hardwoods depend on their age structure.

Height estimation of pine (Pinus eldarica) single trees using slope corrected shadow length on unmanned aerial vehicle (UAV) imagery in a plantation forest

Tree height is one of the key parameters in forest plantations that plays a crucial role in estimation of above-ground biomass (AGB) of trees and stands. The parameter may be obtained by different methods from airborne remotely sensed datasets such shadow length of each tree individual or crown height models (CHMs). However, tree height estimation based on shadow length might be biased considering diverse topography of forest sites. Therefore, this study aims to develop a reliable method to estimate tree height in a plantation forest using shadow length on UAV imagery. First, heights of 151 pine (Pinus eldarica) trees were precisely measured in Pardisan Park, North Khorasan province, Iran. Additionally, a collection of images was captured by a Phantom 4Pro UAV in order to illustrate the study area. Then, two different approaches were considered to estimate the height of trees. In the first approach, tree heights were estimated based on shadow length on the UAV orthomosaic and correcting the effect of slope. The second approach considered the UAV-based CHM and height estimation using CHM segmentation and local maximum filtering. The results showed that tree heights estimated by the first approach were not significantly different from the insitu data (p=0.298). Furthermore, the heights estimated by the slope corrected shadow length showed higher precision compared to the heights estimated by the shadow length without slope correction (Relative root mean squared error, RRMSE 5.6% and 8.2% respectively). However, the heights obtained from the first approach were less precise than the second approach (RRMSE 5.6% and 4.2% respectively). In general, it was concluded that height estimation of pine trees based on shadow length after correction of slope effects can be considered as a reliable approach, although CHM is more efficient in estimating the tree heights. The findings of this study are applicable for height estimation of pine trees within plantation forests on UAV imagery.

Carrying capacity for tree biomass of a subtropical mangrove along a river in Japan inferred from forest structural features

AbstractA subtropical mangrove along the Miyara River in Ishigaki Island, Japan was studied for evaluating the carrying capacity for biomass of the mangrove stands. The stem diameters D, tree height H, and fine roots mass were measured, while aboveground biomass (AGB) and belowground coarse root biomass (BGBcoarse) were estimated. The AGB, BGBcoarse, and fine root mass were estimated as 130, 31, and 13 Mg ha−1 in the Rhizophora stylosa; 271, 94, and 11 Mg ha−1 in the downstream Bruguiera gymnorrhiza; and, 228, 81, and 6.4 Mg ha−1 in the upstream B. gymnorrhiza stand, respectively. The AGB and BGBcoarse in the R. stylosa stand were significantly lower than B. gymnorrhiza stands, and fine root mass was significantly higher than upstream B. gymnorrhiza stand. Significantly lower mean individual phytomass wt specific to tree density ρ of R. stylosa stand than B. gymnorrhiza stand in the ρ − wt relationship denoted the lower carrying capacity for AGB of R. stylosa than that of B. gymnorrhiza. The results showed that high soil pore water salinity and low pH at the downstream did not limit biomass and potential canopy height Hmax of mangrove along a river gradient but AGB and BGBcoarse differed between different species at the same edaphic environment. Analysis of aboveground and belowground biomass variations between stands of two mangrove species along environmental gradients from upstream to downstream could be useful in assessing the consequences of sea level rise in relation to climate change on the evolution of blue carbon dynamics.

Evaluation of multifrequency SAR data for estimating tropical above-ground biomass by employing radiative transfer modeling.

The retrieval of the biophysical parameters and subsequent estimation of the above-ground biomass (AGB) of vegetation stands are made possible by the simulation of the extinction and scattering components from the canopy layer using vector radiative transfer (VRT) theory-based scattering models. With the use of such a model, this study aims to evaluate and compare the potential of dual-pol, multi-frequency SAR data for estimating above-ground biomass. The data selected for this work are L-band dual polarized (HH/HV) ALOS-2 data, S-band dual polarized (HH/HV) NovaSAR data, and C-band dual polarized (VV/VH) Sentinel-1 data. The two key biophysical parameters, tree height, and trunk radius are retrieved using the proposed methodology, applying the frequencies independently. A general allometric equation with vegetation-specific coefficients is used to estimate the AGB from the retrieved biophysical parameters. The retrieval results are validated using ground truth measurements collected from the study area. The L-band, with the coefficient of determination ([Formula: see text]) of 0.73 and the root mean square error (RMSE) of 35.90 t/ha, has the best correlation between the modeled and field AGBs, followed by the S-band with an [Formula: see text] of 0.37 and an RMSE of 63.37 t/ha, and the C-band with an [Formula: see text] of 0.25 and an RMSE of 72.32 t/ha. The L-band has yielded improved estimates of AGB in regression analysis as well, with an [Formula: see text] of 0.48 and an RMSE of 50.02 t/ha, compared to the S- and C-bands, which have the [Formula: see text] of 0.12 and 0.03 and the RMSE of 70.98 t/ha and 80.84 t/ha, respectively.

The Effects of Thinning on Tree Growth and Stand Biomass in a Chronosequence of Pinus tabulaeformis Plantations in the Loess Plateau of China

Thinning plays a vital role in controlling stand density of plantation forests to get quality wood and more ecological function. However, the specific effects of thinning on forest biomass connected with forest age are usually overlooked especially in semi-arid regions. Here, we examined the effects of thinning on individual tree growth and stand biomass in a chronosequence of 20-, 30-, 40-, and 50-year-old Chinese pine (Pinus tabulaeformis) plantations on the Loess Plateau, China. We found that under different thinning managements, both mean diameter at breast height (DBH) and tree height followed the logistic growth pattern, and thinning promoted tree radial growth more than height. The effects of thinning on tree biomass differed between the individual tree and stand level. Thinning could promote individual tree biomass irrespective of stand ages, while stand biomass did not differ between the thinned and unthinned stands at different stand ages. Furthermore, the multiple linear regression analysis and structure equation model showed that individual tree growth was the primary contributor of stand biomass. Thus, we infer that the stand biomass loss after thinning could be mainly compensated by enhanced tree growth, especially radial growth, after a period of recovery (no more than 20 years). The results could provide helpful guidance for forest management and highlighted that reasonable thinning treatment could result in both high individual tree product and stand level harvests in the long term.

Modeling stand biomass for Moso bamboo forests in Eastern China.

Stand biomass models can be used as basic decision-making tools in forest management planning. The Moso bamboo (Phyllostachys pubescens) forest, a major forest system in tropical and subtropical regions, represents a substantial carbon sink, slowing down the rise of greenhouse gas concentrations in the earth's atmosphere. Bamboo stand biomass models are important for the assessment of the contribution of carbon to the terrestrial ecosystem. We constructed a stand biomass model for Moso bamboo using destructively sampled data from 45 sample plots that were located across the Yixing state-owned farm in Jiangsu Province, China. Among several bamboo stand variables used as predictors in the stand biomass models, mean diameter at breast height (MDBH), mean height (MH), and canopy density (CD) of bamboo contributed significantly to the model. To increase the model's accuracy, we introduced the effects of bamboo forest block as a random effect into the model through mixed-effects modeling. The mixed-effects model described a large part of stand biomass variation (R2=0.6987), significantly higher than that of the ordinary least squares regression model (R2=0.5748). Our results show an increased bamboo stand biomass with increasing MH and CD, confirming our model's biological logic. The proposed stand biomass model may have important management implications; for example, it can be combined with other bamboo models to estimate bamboo canopy biomass, carbon sequestration, and bamboo biomass at different growth stages.

Using LiDAR Data to Estimate Biomass in Afforested Bottomland Oak Sites in the Southern United States

Abstract The extent of bottomland hardwood forests in the Lower Mississippi Alluvial Valley (LMAV) has diminished, and federal programs like the Conservation Reserve Program provide incentives to afforest marginal agricultural areas with oaks to provide ecosystem services. Remote sensing technologies, like light detection and ranging (LiDAR), can be used to estimate biomass of these stands to potentially allow landowners to take advantage of carbon markets, but data are expensive to collect. Therefore, we determined whether freely available low-density LiDAR data could capture variability in tree- and stand-level characteristics in the LMAV, including aboveground biomass. We found that multiple regression LiDAR models captured more variability in tree-level than stand-level parameters and including soil type generally improved models. Model r2 values predicting tree and stand parameters including tree height, height to the live crown, quadratic mean diameter, crown area, trees per hectare, stand basal area, and stand biomass ranged from 0.34 to 0.82 and root mean square percent error (RMSPE) ranged from 7% to 36%. Specifically, models for stand biomass had an RMSE of about 19 Mg/ha or about 19% of mean values across sites. Therefore, freely available LiDAR data was useful in evaluating afforested bottomland oak sites for tree- and stand-level structural components in the LMAV.

Stand biomass decreases towards the edge of a range expanding invasive plant, Mikania micrantha, but only on thick soil layers

During spread in the new range, invasive plants may evolve distinctive traits that make them rapidly occupy the suitable and empty sites at the invasion front, such as rapid growth rate and high seed dispersal ability. However, less is known about how competitive ability evolves during range expansion, and no study has examined whether stand biomass (i.e. biomass production of dense monocultural stands, which may indicate the invasion speed and impacts of invasive plants) changes during range expansion. In this study, using 27 populations of an invasive plant, Mikania micrantha, which is expanding its range on Hainan island of China, we examined how competitive ability and stand biomass change along the invasion route. We grew plants of M. micrantha either singly or with common intraspecific competitors originating from different populations in 3 liter pots to evaluate competitive ability, and grew six plants from the same population together in 3 or 11 liter pots to evaluate stand biomass. When grown alone or with competitors, plant biomass and competitive ability did not correlate with distance from invasion center. Stand biomass was negatively correlated with distance from invasion center in 11 liter pots with a thick soil layer, but not in 3 liter pots with a thin soil layer. Stand biomass was negatively correlated with root to shoot ratio (RSR) in 3 liter pots but not in 11 liter pots, possibly because excessive allocation to roots for belowground competition reduced the overall performance at the stand level when soil space was highly limited. Stand biomass was unrelated to competitive ability. Our results indicate that edge populations of invasive plants may have reduced stand level performance in habitats with thick soil layers. In habitats with shallow soil layers, populations of invasive plants may evolve greater allocation to roots and reduced stand level performance.

Stand-Level Biomass and Leaf Trait Models for Young Naturally Regenerated Forests of European Hornbeam

European hornbeam (Carpinus betulus L.) is a tree species widely distributed in Europe and the Asian part of the Near East. However, since European hornbeam is not very attractive for commercial purposes, scientific interest in this species has been rather sparse. Our study focused on dense young (up to 10 years old) European hornbeam stands originating from natural regeneration from seeds in Slovakia because in future the importance of this species may increase due to the climate change. We combined previously constructed tree-level biomass models, data on basic leaf traits, i.e., weight and area, and measurements from thirty plots located at ten different sites across Slovakia to construct stand-level allometric relations of the biomass stock in tree components, i.e., leaves, branches, bark, stem under bark and roots, to mean stand diameter at stem base, i.e., at the ground level. Moreover, we calculated and modelled leaf characteristics, namely the specific leaf area (SLA), leaf area ratio (LAR) and leaf area index (LAI), at a stand level. The total tree biomass stock including all tree components ranged between 0.75 and 13.63 kg per m2, out of which the biomass of stem with bark was from 0.31 to 8.46 kg per m2. The biomass models showed that the contribution of roots (omitting those with a diameter under 2 mm) decreased with the increasing mean stand diameter at stem base, whereas the opposite pattern was observed for branches and stem biomass. Further, we found that the mean stand diameter at stem base was a good predictor of both LAR and LAI. The results indicated the high photosynthetic efficiency of European hornbeam leaves per one-sided surface leaf area. Moreover, the growth efficiency (GE), expressed as the biomass increment of woody parts per leaf area unit, of young European hornbeam trees was high. The models proved a close positive linear correlation between LAI and stand biomass stock that may be used for estimating the biomass in young stands from LAI that can be measured using non-destructive terrestrial or aerial methods. The results further indicated that young stands may sequester a non-negligible quantity of carbon; therefore, they should not be omitted from local or country-wide estimates of carbon stocks in forest vegetation.

Specific Patterns of Tree Stand Biomass Formation Under Different Edaphic and Climatic Conditions

Specific Patterns of Tree Stand Biomass Formation Under Different Edaphic and Climatic Conditions