Aboveground Biomass Allocation Research Articles

G × E × M analysis to define allometric rules between leaves and stems in wheat.

Allometric rules provide insights into the structure-function relationships across species and scales and are commonly used in ecology. The fields of agronomy, plant phenotyping and modeling also need simplifications such as allometric rules to reconcile data at different temporal and spatial levels (organs/canopy). This paper explores the variations in relationships for wheat regarding (i) the distribution of crop green area between leaves and stems, and (ii) the allocation of above-ground biomass between leaves and stems during the vegetative period, using a large dataset covering different years, countries, genotypes and management practices. Our results show that the relationship between leaf and stem area was linear, genotype-specific, and sensitive to radiation. The relationship between leaf and stem biomass depended on genotype and nitrogen fertilization. The mass per area, associating area and biomass for both leaf and stem, varied strongly by developmental stage and was significantly affected by environment and genotype. These allometric rules were evaluated with satisfactory performance, and their potential use is discussed with regard to current phenotyping techniques and plant/crop models. Our results enable the definition of models and minimum datasets required for characterizing diversity panels and making predictions in various G × E × M contexts.

Interspecies diversity in morphological responses to water stress: Study on a panel of weed and crop species

Climate change modifies the dynamics and the quantity of plant water supply, and plant morphological response to environmental factors plays a key role in crop-weed interactions. This study investigated the interspecies diversity related to the morphological responses of annual herbaceous species to water stress. Key morphological traits were measured at two growth stages on five weed and two crop (soft wheat, rapeseed) species grown on a gradient of water availability in a greenhouse experiment. For each trait, response curves to water stress were defined, and their parameters were used to quantify interspecies diversity. Generic morphological response patterns were identified across all species and plant stages. Water stress reduced leaf area per unit leaf biomass (SLA, lowering water demand) and increased the ratio of plant height to aboveground biomass for all species (HBR, keeping access to light). In most situations, the ratio of root biomass over total biomass (RBR) increased (improving water uptake). Variability in parameter values of morphological traits was primarily explained by the species, followed by growth stage. Geranium dissectum L. and Abutilon theophrasti Medik. were the most responsive species to water stress, especially at the flowering stage, with strong RBR and HBR increase and slight SLA decrease. Species differences were not related to clade (monocotyledonous/dicotyledonous) nor status (weed/crop), despite a near-significant clade effect on allocation of aboveground biomass, with grass species allocating more biomass to stems (vs leaves), while no general tendency was observed in broadleaved species. These findings provide new insights on comparative ecology of weed and crop species response to water limitation, and more research is expected to cover a wider range of weed and crop species.

Species-specific responses of C and N allocation to N addition: evidence from dual 13C and 15N labeling in three tree species

Soil nitrogen (N) availability affects plant carbon (C) utilization. However, it is unclear how various tree functional types respond to N addition in terms of C assimilation, allocation, and storage. Here, a microcosm experiment with dual 13C and 15N labeling was conducted to study the effects of N addition (i.e., control, 0 g N kg−1; moderate N addition, 1.68 g N kg−1; and high N addition, 3.36 g N kg−1 soil) on morphological traits, on changes in nonstructural carbohydrates (NSC) in different organs, as well as on C and N uptake and allocation in three European temperate forest tree species (i.e., Acer pseudoplatanus, Picea abies and Abies alba). Our results demonstrated that root N uptake rates of the three tree species increased by N addition. In A. pseudoplatanus, N uptake by roots, N allocation to aboveground organs, and aboveground biomass allocation significantly improved by moderate and high N addition. In A. alba, only the high N addition treatment considerably raised aboveground N and C allocation. In contrast, biomass as well as C and N allocation between above and belowground tissues were not altered by N addition in P. abies. Meanwhile, NSC content as well as C and N coupling (represented by the ratio of relative 13C and 15N allocation rates in organs) were affected by N addition in A. pseudoplantanus and P. abies but not in A. alba. Overall, A. pseudoplatanus displayed the highest sensitivity to N addition and the highest N requirement among the three species, while P. abies had a lower N demand than A. alba. Our findings highlight that the responses of C and N allocation to soil N availability are species-specific and vary with the amount of N addition.

Climate Factors Influence Above- and Belowground Biomass Allocations in Alpine Meadows and Desert Steppes through Alterations in Soil Nutrient Availability.

Biomass is a direct reflection of community productivity, and the allocation of aboveground and belowground biomass is a survival strategy formed by the long-term adaptation of plants to environmental changes. However, under global changes, the patterns of aboveground-belowground biomass allocations and their controlling factors in different types of grasslands are still unclear. Based on the biomass data of 182 grasslands, including 17 alpine meadows (AMs) and 21 desert steppes (DSs), this study investigates the spatial distribution of the belowground biomass allocation proportion (BGBP) in different types of grasslands and their main controlling factors. The research results show that the BGBP of AMs is significantly higher than that of DSs (p < 0.05). The BGBP of AMs significantly decreases with increasing mean annual temperature (MAT) and mean annual precipitation (MAP) (p < 0.05), while it significantly increases with increasing soil nitrogen content (N), soil phosphorus content (P), and soil pH (p < 0.05). The BGBP of DSs significantly decreases with increasing MAP (p < 0.05), while it significantly increases with increasing soil phosphorus content (P) and soil pH (p < 0.05). The random forest model indicates that soil pH is the most important factor affecting the BGBP of both AMs and DSs. Climate-related factors were identified as key drivers shaping the spatial distribution patterns of BGBP by exerting an influence on soil nutrient availability. Climate and soil factors exert influences not only on grassland biomass allocation directly, but also indirectly by impacting the availability of soil nutrients.

Link between the aboveground and belowground biomass allocation with growing of Tamarix sp. seedlings in the hinterland of Taklimakan Desert, China.

The morphological characteristics and biomass allocation can reflect plant adaptive strategies to the environment. Tamarix sp. is an excellent shrub species used for windbreaks and fixing sand in the desert of northwest China. The successful establishment of Tamarix sp. seedlings and their growth into mature individuals require their adaptation to various environmental conditions, which is the key to naturally regenerating the Tamarix population. To clarify the root morphological characteristics, leaf structural characters, and biomass allocation of Tamarix sp. seedlings in response to drought conditions, we took the Tamarix sp. seedlings at the Daryaboyi oasis in the hinterland of Taklimakan Desert as the object of study, analyzed rooting depth, root dry weight (RDW), specific root length (SRL), root surface area (RA), specific root area (SRA), leaf area (LA), specific leaf area (SLA) and root: shoot ratio (R:S ratio). The gravimetric soil water content varied from 5.80% to 25.84% in this study area. The taproots of Tamarix sp seedlings with small basal stem diameters were shallower and had few lateral root branches and Tamarix sp. seedlings with large basal stem diameters had more obvious taproots and lateral roots. With the growth of Tamarix sp. seedlings, the taproot deepened, and the values ranged from 4.5 cm to 108.0 cm; the SRL, SRA, and SLA decreased, and the ranges of the values were 28.92-478.79 cm·g-1, 1.07-458.50 cm2·g-1, and 24.48-50.7 cm2·g-1; the RDW, RA, and LA increased, the ranges of the values were 0.16-21.34 g, 3.42-328.04 cm2, and 2.41-694.45 cm2; the more biomass was allocated to the aboveground parts, and the mean R: S ratio was 0.76. In better soil water conditions, the root growth rate decreased as Tamarix sp. seedlings grew, and more biomass was allocated to the aboveground. This further showed that stable surface water is highly significant to the biomass allocation strategy of Tamarix sp. seedlings.

Plants alter their aboveground and belowground biomass allocation and affect community-level resistance in response to snow cover change in Central Asia, Northwest China

It is important to elucidate the changing distribution pattern of net primary productivity (NPP) to mechanistically understand the changes in aboveground and belowground ecosystem functions. In water-scarce desert environments, snow provides a crucial supply of water for plant development and the spread of herbaceous species. Yet uncertainty persists regarding how herbaceous plants' NPP allocation responds to variation in snow cover. The goal of this study was to investigate how variation in snow cover in a temperate desert influenced the NPP allocation dynamics of herbaceous species and their resistance to environmental change in terms aboveground and belowground productivity. In the Gurbantunggut Desert, wintertime snow cover depth was adjusted in plots by applying four treatments: snow removal (−S), ambient snow, double snow (+S), and triple snow (+2S). We examined their species richness, aboveground NPP (ANPP), belowground NPP (BNPP), and the resistance of ANPP and BNPP. We found that species diversity of the aboveground community increased significantly with increasing snow cover and decreased significantly Pielou evenness in plots. This resulted in greater ANPP with increasing snow cover; meanwhile, BNPP first increased and then decreased with increasing snow cover. However, this productivity in different soil layers responded differently to changed snow cover. In the 0–10 cm soil layer, productivity first rose and then declined, while it declined linearly in both the 10–20 cm and 20–30 cm soil layers, whereas in the 30–40 cm soil layer it showed an increasing trend. Belowground resistance would increase given that greater snow cover improved the BNPP in deeper soil and maintained the resource provisioning for plant growth, thus improving overall belowground stability. These results can serve as a promising research foundation for future work on how the functioning of desert ecosystems becomes altered due to changes in plant community expansion and, in particular, changes in snow cover driven by global climate change.

Vertical distribution patterns of community biomass, carbon and nitrogen content in grasslands on the eastern Qinghai–Tibet Plateau

The accumulation, transport and distribution of photosynthates within plants not only affect the ratio of shoot-to-root biomass, but also change the distribution pattern of nutrient elements in different organs and tissues. A full understanding of the allocation patterns of biomass and nutrient elements within plants, is helpful to strengthen our understanding of the above- and belowground ecosystem functions. However, at present, we do not know enough about the aboveground–belowground allocation of biomass, carbon (C) and nitrogen (N) contents, and, in particular, the corresponding vertical distribution pattern belowground and its environmental impact. At the community scale, the changes in vegetation community attributes measured in the field can reflect the long-term adaptation and subsequent adaptation strategies of vegetation to the regional environment and environmental changes. In this study, the vertical distribution patterns of community biomass and the carbon and nitrogen contents with soil depth in an alpine grassland on the eastern Qinghai–Tibet Plateau were investigated based on the transect method. Our results show the following: (1) Alpine grasslands can respond to differences in hydrothermal resource availability by changing biomass allocation patterns. In low-temperature and high-humidity environments, aboveground and belowground biomass allocation supports the isometric growth hypothesis. However, in environments with less soil moisture or high temperature and humidity, the aboveground and belowground biomass distributions support the allometric allocation hypothesis. (2) The vertical distribution patterns of the C content, N content and carbon: nitrogen ratio (C:N) within plants are different. From the leaves to the root system, with the increase in root depth, the C content demonstrated a vertical distribution pattern of first decreasing and then increasing, and the N% demonstrated a gradual decreasing distribution pattern, while the C:N ratio demonstrated an exponential increasing distribution pattern. (3) The change rate in C%, N% and C:N related to the soil depth was affected by environmental hydrothermal conditions. C% and C:N ratio changed more rapidly with root depth under low temperature and high humidity. The change rate of N% was mainly affected by temperature and changed more rapidly with root depth at low temperatures. (4) When exploring the relationship between the content of elements within plants, it is necessary to combine both the above- and belowground compartments. There was a nonlinear quadratic relationship between the carbon and nitrogen contents within plants.

Precipitation Dominates the Allocation Strategy of Above- and Belowground Biomass in Plants on Macro Scales.

The allocation of biomass reflects a plant's resource utilization strategy and is significantly influenced by climatic factors. However, it remains unclear how climate factors affect the aboveground and belowground biomass allocation patterns on macro scales. To address this, a study was conducted using aboveground and belowground biomass data for 486 species across 294 sites in China, investigating the effects of climate change on biomass allocation patterns. The results show that the proportion of belowground biomass in the total biomass (BGBP) or root-to-shoot ratio (R/S) in the northwest region of China is significantly higher than that in the southeast region. Significant differences (p < 0.05) were found in BGBP or R/S among different types of plants (trees, shrubs, and herbs plants), with values for herb plants being significantly higher than shrubs and tree species. On macro scales, precipitation and soil nutrient factors (i.e., soil nitrogen and phosphorus content) are positively correlated with BGBP or R/S, while temperature and functional traits are negatively correlated. Climate factors contribute more to driving plant biomass allocation strategies than soil and functional trait factors. Climate factors determine BGBP by changing other functional traits of plants. However, climate factors influence R/S mainly by affecting the availability of soil nutrients. The results quantify the productivity and carbon sequestration capacity of terrestrial ecosystems and provide important theoretical guidance for the management of forests, shrubs, and herbaceous plants.

A response of biomass and nutrient allocation to the combined effects of soil nutrient, arbuscular mycorrhizal, and root-knot nematode in cherry tomato

IntroductionThe biomass and nutrient allocation strategies in plants are fundamental for predicting carbon storage and mineral and nutrient cycles in terrestrial ecosystems. However, our knowledge regarding the effects of multiple environmental factors on biomass and nutrient allocation remains limited.MethodsHere we manipulated soil composition (three levels), arbuscular mycorrhizal fungi inoculation (AMF, five levels), and root-knot nematode inoculation (RKN, two levels) using random block design to reveal the effects of these factors on biomass and nutrient allocation strategies of cherry tomato.Results and DiscussionOur results showed that biomass and nutrient allocation were affected by soil composition, AMF and RKN individually or interactively. The biomass and nutrient allocation in cherry tomato shows different adaptation strategies responded to the joint action of three factors. The reduction of soil nutrients increased belowground biomass allocation, and aboveground nitrogen and phosphorus concentration. AMF colonization increased aboveground biomass allocation and reproductive investment and promoted aboveground nitrogen and phosphorus inputs. Cherry tomato can mitigate the stress of RKN infection by investing more biomass and nutrients into belowground organs. Our study showed that plants can adjust their survival strategies by changing biomass and nutrient allocation to adapt to variation in soil abiotic and biotic factors. These findings contribute to our understanding of the adaptive processes of plant biomass and nutrient allocation strategies under multiple environmental factors.

Above-ground biomass allocation and potential carbon sink of black pine – a case study from southern Poland

Biomass allocation is a key factor for understanding the forest carbon balance and reflects plants’ ecological strategies in different environmental conditions. Allocation patterns and biomass models outside of the native range of black pine have not been analyzed in the context of the observed climate changes. The study's goals were to develop biomass equations for mature black pine from southern Poland and assess biomass and carbon allocation patterns and the potential of trees of different social statuses for carbon sequestration. A total of 129 felled black pine trees were measured, among which 14 were destructively sampled to determine biomass and carbon content in tree components. The developed set of biomass equations provided allocation patterns and accumulation of trees of different social statuses. Biomass and carbon allocation patterns were different but related to tree social status. The introduction of diameter at crown base significantly improved the accuracy of the developed models. The analyzed trees allocated relatively more in stem than in crown in comparison with that observed in other studies. Biomass and carbon allocation patterns of the analyzed black pines differ from those of the native range. They should be considered in biomass modeling with factors influencing social status structure.

Plant biomass allocation is mediated by precipitation use efficiency in arid and semiarid ecosystems

AbstractThe arid and semiarid grassland ecosystems are characterized by limited water resources and are generally vulnerable to climate change. Understanding how plants in arid and semiarid ecosystems respond to global climatic variation is crucial for ecological restoration under a changing climate. Although the effects of climate on aboveground biomass (AGB) and belowground biomass (BGB) have been widely explored, how AGB and BGB respond to climatic variation is seldom disentangled. There is still a need to understand how plant communities respond to global climate change. In this study, we conducted a transect survey across grasslands in Inner Mongolia to capture changes in AGB and BGB in plant communities. Then, we used structural equation modelling (SEM) to explore the relationship between environmental factors and the root:shoot ratio to understand how plant communities respond to ecological drought under global climate change. Our results showed that low precipitation use efficiency (LPUE) results in a high root:shoot (HRS) ratio, and BGB was more sensitive to environmental changes. By contrast, high precipitation use efficiency (HPUE) led to a low root:shoot (LRS) ratio, and environmental factors had a greater impact on AGB. For the LPUE pattern, soil water content (SWC), pH, and soil total nitrogen (STN) mainly affected the HRS ratio. Soil water content and STN influenced the HRS ratio through a positive effect on BGB . For the HPUE pattern, SWC, STN, and plant abundance (PA) predominantly regulate the LRS ratio, while biodiversity (plant abundance) affects the LRS ratio by positively affecting AGB. Our results highlight the differential impact of precipitation use efficiency on aboveground and belowground biomass allocation. This is important for monitoring the impact of drought events on plant biomass, improving productivity assessment models in arid and semi‐arid regions, and assessing local carbon storage accurately.

Biomass allocation and carbon stock in Douglas fir and Norway spruce at the tree and stand level

Abstract The effect of changing tree species composition in favor of a greater representation of Douglas fir at the expense of Norway spruce on the carbon pool of Central European forests has not yet been investigated. Here, we compare the allocation of aboveground biomass and carbon stock in Douglas fir and spruce at the tree and stand level. At the tree level, Douglas fir accumulated, on average, 16.9% more aboveground biomass than Norway spruce. A greater amount of biomass was allocated mainly in the wood and bark of Douglas fir stem. For these biomass compartments, the difference between Douglas fir and Norway spruce was 21.1% and 60.3%, respectively. Spruce allocated more biomass in the crown, where the difference was 25.6% compared to Douglas fir. In needle biomass, Norway spruce exceeded Douglas fir by 84%. At the stand level, the analysis of model stands revealed that pure Norway spruce stands accumulated more carbon in the high and medium quality sites. As the site quality decreased, so did the differences in the amount of stored carbon. The higher carbon sink in Norway spruce stands was also confirmed in the analysis of real Norway spruce and Douglas fir stands. The difference in the carbon stock of young, medium-aged, and mature stands was 11.5%, 14.8%, and 1%, respectively. The positive balance in favor of spruce is mainly due to significantly higher numbers of trees per ha in Norway spruce stands. A positive effect of a greater representation of Douglas fir on the carbon budget of forest stands was not confirmed.

Effects of light intensity and nitrogen deposition on ecophysiological characteristics of Coreopsis grandiflora1

Light heterogeneity commonly occurs in natural environments, and N deposition has increased sharply in recent decades, affecting both the growth and invasion of exotic plants. We used an exotic species, Coreopsis grandiflora, distributed in natural and urban areas throughout China, to study the combined effects of light exposure and N addition on leaf physiology, height, crown area, total biomass (TB), and phenotypic plasticity. We exposed C. grandiflora seedlings to one of three light (15, 65, and 100% of full irradiation) and one of three nitrogen treatments (0, 8, and 20 g N m–2 yr–1). The shade significantly increased leaf chlorophyll, N, and P concentrations, aboveground biomass allocation, and specific leaf area, allowing plants to capture more light, which did not result in a change in TB, indicating that C. grandiflora seedlings have shade tolerance. Nitrogen addition generally increased the TB, leaf biomass, crown area and leaf N concentration. In addition, N supply did not increase TB of C. grandiflora in the shade. For approximately half of the traits measured, the phenotypic plasticities of C. grandiflora responding to light differ greatly from those responding to N addition. Under light and N deposition treatments, photosynthetic N use efficiency had higher phenotypic plasticity than other leaf physiological traits, whereas the maximum quantum yield of photosystem II, leaf N, and P concentrations had lower phenotypic plasticity, suggesting that hierarchical plasticity occurs among the various leaf physiological traits. Light intensity increased the plasticity of C. grandiflora in response to N deposition. Thus, with high plasticity, invasiveness of C. grandiflora may increase under high N deposition and illumination conditions.

Aboveground biomass allocation and additive allometric models of fifteen tree species in northeast China based on improved investigation methods

Tree allometric models are crucial to accurate forest biomass assessment, but the acquisition of biomass data is one of the most important limitations in establishing biomass models. This study aims to propose an improved investigation method to quickly and practically obtain biomass data, establish species-specific allometric equations and evaluate the biomass allocation pattern for various tree species in a broad-leaved Korean pine forest in northeast China. Based on the non-destructive measurement and sampling of 390 trees from 15 tree species, partial and aggregate biomass models with DBH and DBH2 × H as predictors were established. Results indicated that all allometric models could effectively estimate the dependent variables, and almost no antilog correction was required. Specifically, for the stem and bark components of most tree species, using the DBH2 × H predictor improved the prediction performance of the model. However, DBH was the best predictor for branch and leaf biomass models. The biomass allocation of trees was affected by tree diameter. Small-diameter trees (DBH < 8) had more leaf investment than other size trees, medium-diameter trees (8 < DBH < 20) increased the allocation of resources to stems, and large-diameter trees (DBH > 20) paid more attention to the growth and accumulation of branches. Our allometric model and biomass allocation research based on the non-destructive measurement and sampling will help improve the accuracy of biomass assessment in broad-leaved Korean pine forests and advance our understanding of woody plant development and survival strategies.

Effect of rainfall on Artemisia ordosica Krasch anual net primary production and allocation in sandy land in China

The adjustment of aboveground biomass allocation is an important part of plant growth adaptation strategies. Due to global climate change, rising temperatures are causing changes in global air circulation patterns. Therefore, more extreme drought and flood events will happen in the future. Xerophytic shrubs are the main vegetation types of dryland ecosystems and are expected to be sensitive to changes in rainfall, which would inevitably affect the stability of the ecosystem. We conducted field experiments to simulate the effects of rainfall on Artemisia ordosica Krasch annual net primary productivity (ANPP) and allocation in the Mu Us Desert in northern China. This study examined six different rainfall levels: natural rainfall level (control); natural rainfall level reduced by 30%, 50%, and 70% (−30%, −50%, −70% treatment); and natural rainfall level increased by 30% and 50% (+30%, +50% treatment). The plant height, cover/volume, size/number of vegetative and reproductive twigs, and dry weight of vegetative and reproductive twigs were measured. The results showed the following: (1) Twig size and number are more sensitive to rainfall changes than the cover/volume of this species. (2) Rainfall has a significant influence on shrub ANPP (maximum ANPP was reached at + 30% treatment, and the minimum value was reached at −70% treatment). (3) With the increase or decrease of rainfall, A. ordosica number of twigs increased, and the length became shorter. (4) Rainfall had a significant effect on ANPP allocation (vegetative growth and reproductive growth). With the increase or decrease of rainfall, vegetative growth and reproductive growth of A. ordosica showed a trade-off strategy. Under the condition of adding rainfall, vegetative twig ANPP increased significantly. Under severe drought stress (-70% treatment), ANPP decreased significantly. Adding or subtracting rainfall caused a significant decrease in the vegetative twig ANPP ratio and a significant increase in the reproduction twig ANPP ratio. Our results highlight the sensitivity of twig size and number as indicators of shrub production estimation and the mechanism underpinning desert shrub ANPP response to global environmental changes.

The relationship of the main root-shoot morphological characteristics and biomass allocation of Saussurea salsa under different habitat conditions in Sugan lake wetland on the northern margin of the Qinghai-Tibet Plateau

The response analysis of plant morphological characteristics and biomass allocation in salt marsh wetland to heterogeneous habitats is helpful to explore the internal correlation between plant morphological plasticity mechanism and biomass allocation, which is of great significance for the in-depth understanding of habitat stress tolerance strategies of salt marsh plants. However, the relationship between the main root-shoot morphological indexes and biomass allocation of inland alpine arid area salt marsh plant is still unclear. According to the difference of the habitat conditions of Saussurea salsa, 3 test sample were set up, plot I (the Inland salt marsh area, 200–500 m from the lakeshore), plot II (the Oasis Wetland area, 500–1000 m from the lakeshore), plot III (the Seasonal river wetland area, 1000–1500 m from the lakeshore). The relationship between the main root-shoot morphological characteristics and biomass allocation of Saussurea salsa in the Sugan Lake salt marsh was studied in response to heterogeneous habitats. The results showed that Saussurea salsa tended to form the large and thick leaf pattern, the root morphological construction pattern with moderate root diameter (RD) and specific root length (SRL), and the root-shoot ratio (RSR) with minimum biomass allocation strategy in plot I. In plot II, the thin-leaf pattern with the largest specific leaf area (SLA) and the smallest thickness (LT) was formed. Meanwhile, the slender root morphology pattern with the smallest RD, the largest SRL and the moderate RSR was preferred. In plot III, a lobular pattern with minimum leaf area (LA) and SLA, and moderate thickness was formed. At the same time, a thick root pattern with maximum RD and minimum root length, and a maximum RSR were formed. Moreover, there was a highly significant negative correlation (p < 0.01) between SLA and RD at three plots. Besides, there appeared a less significant positive correlation (p < 0.05) between LA and LT, shoot biomass at three plots. Through the synergistic changes of morphological characteristics of aboveground and underground organs and biomass allocation strategies, the inland salt marsh plant population can maintain normal survival, growth and reproduction under harsh environment, which reflects its morphological plasticity and stress resistance mechanism under heterogeneous environment.

Tropical tree allometry and crown allocation, and their relationship with species traits in central Africa

Common allometric patterns have been reported across the tropics and good performance on independent data was retrieved for the most recent pantropical model predicting tree aboveground biomass (AGB) from stem diameter, wood density and total height. General models are undoubtedly useful for the estimation and monitoring of biomass and carbon stocks in tropical forests, however specific allometry, allocation, and traits, are at the core of many models of vegetation dynamics, and there is lack of such information for some regions and species. In this study, we specifically evaluated how size-dependent changes in above-ground biomass and biomass allocation to crown relate to other allometric and life-history traits for tropical tree species. We gathered destructive data available in eight terra firme forest sites across central Africa and the combined dataset consisted of 1,023 trees belonging to 54 tropical tree species phylogenetically dispersed, with only two congeneric species. A huge body of field and laboratory measurements was used for computing AGB and crown mass ratio (CMR) at the tree level, and to derive key allometric traits at the species level. For the latter, species-specific relationships between tree diameter and total height, crown exposure to light, wood density, and bark thickness were fitted for 50 species. Our results show interspecific variation in the relationships relating tree diameter to both AGB and CMR, and including species traits in a multi-specific AGB model confirmed that interspecific variation in biomass allometry is primarily determined by species wood density. We also showed that the allocation of biomass to crown increases linearly with tree diameter for most species, and that interspecific variation in the CMR model is associated with the species dispersal mode and maximum height. Trait covariations among our set of tropical tree species widespread and/or locally abundant in central Africa, revealed a continuum between large-statured species, which tended to be light-demanding, deciduous and wind-dispersed, and species with opposite attributes. Information on allometry, allocation, and traits provided here could further be used in comparative ecology and for parameterizing dynamic and succession models. Also importantly, the species-specific AGB models fitted for major tree species, including most timber species of central Africa, will help improve biomass estimates.

Changes of Aboveground and Belowground Biomass Allocation in Four Dominant Grassland Species Across a Precipitation Gradient.

Climate change is predicted to affect plant growth, but also the allocation of biomass to aboveground and belowground plant parts. To date, studies have mostly focused on aboveground biomass, while belowground biomass and allocation patterns have received less attention. We investigated changes in biomass allocation along a controlled gradient of precipitation in an experiment with four plant species (Leymus chinensis, Stipa grandis, Artemisia frigida, and Potentilla acaulis) dominant in Inner Mongolia steppe. Results showed that aboveground biomass, belowground biomass and total biomass all increased with increasing growing season precipitation, as expected in this water-limited ecosystem. Biomass allocation patterns also changed along the precipitation gradient, but significant variation between species was apparent. Specifically, the belowground biomass: aboveground biomass ratio (i.e., B:A ratio) of S. grandis was not impacted by precipitation amount, while B:A ratios of the other three species changed in different ways along the gradient. Some of these differences in allocation strategies may be related to morphological differences, specifically, the presence of rhizomes or stolons, though no consistent patterns emerged. Isometric partitioning, i.e., constant allocation of biomass aboveground and belowground, seemed to occur for one species (S. grandis), but not for the three rhizome or stolon-forming ones. Indeed, for these species, the slope of the allometric regression between log-transformed belowground biomass and log-transformed aboveground biomass significantly differed from 1.0 and B:A ratios changed along the precipitation gradient. As changes in biomass allocation can affect ecosystem functioning and services, our results can be used as a basis for further studies into allocation patterns, especially in a context of environmental change.

Aboveground Biomass Allocation of Boreal Shrubs and Short-Stature Trees in Northwestern Canada

In this follow-on study on aboveground biomass of shrubs and short-stature trees, we provide plant component aboveground biomass (herein ‘AGB’) as well as plant component AGB allometric models for five common boreal shrub and four common boreal short-stature tree genera/species. The analyzed plant components consist of stem, branch, and leaf organs. We found similar ratios of component biomass to total AGB for stems, branches, and leaves amongst shrubs and deciduous tree genera/species across the southern Northwest Territories, while the evergreen Picea genus differed in the biomass allocation to aboveground plant organs compared to the deciduous genera/species. Shrub component AGB allometric models were derived using the three-dimensional variable volume as predictor, determined as the sum of line-intercept cover, upper foliage width, and maximum height above ground. Tree component AGB was modeled using the cross-sectional area of the stem diameter as predictor variable, measured at 0.30 m along the stem length. For shrub component AGB, we achieved better model fits for stem biomass (60.33 g ≤ RMSE ≤ 163.59 g; 0.651 ≤ R2 ≤ 0.885) compared to leaf biomass (12.62 g ≤ RMSE ≤ 35.04 g; 0.380 ≤ R2 ≤ 0.735), as has been reported by others. For short-stature trees, leaf biomass predictions resulted in similar model fits (18.21 g ≤ RMSE ≤ 70.0 g; 0.702 ≤ R2 ≤ 0.882) compared to branch biomass (6.88 g ≤ RMSE ≤ 45.08 g; 0.736 ≤ R2 ≤ 0.923) and only slightly better model fits for stem biomass (30.87 g ≤ RMSE ≤ 11.72 g; 0.887 ≤ R2 ≤ 0.960), which suggests that leaf AGB of short-stature trees (&lt;4.5 m) can be more accurately predicted using cross-sectional area as opposed to diameter at breast height for tall-stature trees. Our multi-species shrub and short-stature tree allometric models showed promising results for predicting plant component AGB, which can be utilized for remote sensing applications where plant functional types cannot always be distinguished. This study provides critical information on plant AGB allocation as well as component AGB modeling, required for understanding boreal AGB and aboveground carbon pools within the dynamic and rapidly changing Taiga Plains and Taiga Shield ecozones. In addition, the structural information and component AGB equations are important for integrating shrubs and short-stature tree AGB into carbon accounting strategies in order to improve our understanding of the rapidly changing boreal ecosystem function.

Aboveground biomass allocation patterns and model construction of Bambusa rigida

Aboveground biomass allocation patterns and model construction of Bambusa rigida