Aboveground Biomass Accumulation Research Articles

The Synergetic Effect of Light Spectra and Selenium Supplementation on Eruca sativa Mill. Growth and Physiological and Metabolic Responses

Eco-friendly lighting systems, like LED lights, can reduce energy consumption in greenhouse operations, have a long lifespan, and enable precise control over plant growth through spectrum selection. On the other hand, Selenium (Se) is a micronutrient with a beneficial role in plant metabolism and an essential element for human health. In this study, we aim to unravel the effects of LED lighting combined with Se supplementation on the physiological behavior, yield, and quality of arugula (Eruca sativa). Arugula plants were cultivated under controlled conditions using two distinct LED lights: full white spectrum (W) and a mix of 80%/20% of red/blue light (R:B). These plants were then supplemented with three levels of Se: 0 mg Se kg−1 soil [0], 0.3 mg Se kg−1 soil [0.3], and 0.6 mg Se kg−1 soil [0.6]. The results showed that stomatal conductance remained unaffected by the light script. However, the plants exposed to R:B displayed more pronounced signs of photodamage and reduced net photosynthetic rate. Supplementation with Se plays a significant role in mitigating light-induced stress and in improving the antioxidant defense system; this was especially notable in R:B plants. Finally, R:B light decreased the accumulation of aboveground biomass, while no significant impact of Se was noticed on this outcome. Se accumulation exhibited a direct and proportional relationship with the concentration of Se applied. The integration of LED technology and Se supplementation not only enhances crop nutritional value but also aligns with the adoption of more sustainable agricultural practices.

Aboveground biomass stocks of species-rich natural forests in southern China are influenced by stand structural attributes, species richness and precipitation

Forests, the largest terrestrial carbon sinks, play an important role in carbon sequestration and climate change mitigation. Although forest attributes and environmental factors have been shown to impact aboveground biomass, their influence on biomass stocks in species-rich forests in southern China, a biodiversity hotspot, has rarely been investigated. In this study, we characterized the effects of environmental factors, forest structure, and species diversity on aboveground biomass stocks of 30 plots (1 ha each) in natural forests located within seven nature reserves distributed across subtropical and marginal tropical zones in Guangxi, China. Our results indicate that forest aboveground biomass stocks in this region are lower than those in mature tropical and subtropical forests in other regions. Furthermore, we found that aboveground biomass was positively correlated with stand age, mean annual precipitation, elevation, structural attributes and species richness, although not with species evenness. When we compared stands with the same basal area, we found that aboveground biomass stock was higher in communities with a higher coefficient of variation of diameter at breast height. These findings highlight the importance of maintaining forest structural diversity and species richness to promote aboveground biomass accumulation and reveal the potential impacts of precipitation changes resulting from climate warming on the ecosystem services of subtropical and northern tropical forests in China. Notably, many natural forests in southern China are not fully stocked. Therefore, their continued growth will increase their carbon storage over time.

Contrasting roles of plant, bacterial, and fungal diversity in soil organic carbon accrual during ecosystem restoration: A meta-analysis

Plant and microbial diversity plays vital roles in soil organic carbon (SOC) accumulation during ecosystem restoration. However, how soil microbial diversity mediates the positive effects of plant diversity on carbon accumulation during vegetation restoration remains unclear. We conducted a large-scale meta-analysis with 353 paired observations from 65 studies to examine how plant and microbial diversity changed over 0–160 years of natural restoration and its connection to SOC accrual in the topsoil (0–10 cm). Results showed that natural restoration significantly increased plant aboveground biomass (122.09 %), belowground biomass (153.05 %), and richness (21.99 %) and SOC accumulation (32.34 %) but had no significant impact on microbial diversity. Over time, bacterial and fungal richness increased and then decreased. The responses of major microbial phyla, in terms of relative abundance, varied across restoration and ecosystem types. Specifically, Ascomycota and Zygomycota decreased more under farmland abandonment than under grazing exclusion. In forest, Bacteroidetes, Ascomycota, and Zygomycota significantly decreased after natural restoration. The increase in SOC and Basidiomycota was higher in forest than in grassland. Based on standardized estimates, structural equation modeling showed that plant diversity had the highest positive effect (0.55) on SOC accrual, and while fungal diversity (0.15) also had a positive effective, bacterial diversity (−0.20) had a negative effect. Plant diversity promoted SOC accumulation by directly impacting biomass and soil moisture and total nitrogen and indirectly influencing soil microbial richness. This meta-analysis highlights the significant roles of plant diversity and microbial diversity in carbon accumulation during natural restoration and elucidates their relative contributions to carbon accumulation, thereby aiding in more precise predictions of soil carbon sequestration.

Grain yield, water-land productivity and economic profit responses to row configuration in maize-soybean strip intercropping systems under drip fertigation in arid northwest China

Intercropping has great potential for alleviating arable land competition, improving land output and promoting sustainable agricultural development. However, the applicability of maize-soybean strip intercropping under drip fertigation in arid northwest China remains unclear, especially under various row configurations. A two-season (2022 and 2023) field experiment was performed in the Hexi Region of northwest China to investigate the responses of plant growth, yield performance, water-land productivity and economic profit of drip-fertigated maize-soybean strip intercropping systems to eight row configurations. The results showed that intercropping significantly reduced aboveground biomass accumulation of maize and soybean by 18.77% and 47.81% on average compared to monocropping, respectively. Intercropping significantly decreased the 100-grain weight, ear length and ear width of maize, and reduced the 100-grain weight and pod number of soybean, resulting in reduced grain yields of intercropped maize and soybean (by 13.08% and 48.73%, respectively), but two rows of maize alternating with four rows of soybean (M2S4), three rows of maize alternating with four rows of soybean (M3S4), four rows of maize in wide and narrow rows alternating with four rows of soybean (M4S4-MN), and four rows of maize in wide and narrow rows alternating with six rows of soybean (M4S6-MN) produced greater population grain yield compared to monocropping. Among all intercropping systems, the largest water-land productivity and economic profit occurred in M2S4 (1.61 in 2022 and 1.42 in 2023 for land equivalent ratio; 29.23 kg ha−1 mm−1 in 2022 and 28.22 kg ha−1 mm−1 in 2023 for water productivity; 23,965 CNY ha−1 in 2022 and 23,059 CNY ha−1 in 2023 for economic profit), followed by M4S4-MN (1.53 in 2022 and 1.36 in 2023 for land equivalent ratio; 27.11 kg ha−1 mm−1 in 2022 and 26.58 kg ha−1 mm−1 in 2023 for water productivity; 22,327 CNY ha−1 in 2022 and 22,224 CNY ha−1 in 2023 for economic profit). The M2S4 is thus the optimal row configuration for drip-fertigated maize-soybean strip intercropping systems in terms of grain yield, economic profit and land productivity, while the M4S4-MN is recommended by further considering the efficiency of mechanized sowing and harvesting.

Effect of fertilization and microbial preparations on productivity of chickpea (<i>Cicer arietinum</i> L.)

The aim of the study was to optimize the nutritional status and increase the productivity of chickpeas through the application of mineral and organic-mineral fertilizers as well as microbial preparations based on nitrogen–fixing, phosphorus–mobilizing, and potassium-mobilizing microorganisms. The research was conducted in 2019-2021 in the Poltava Research Agricultural Station (Ukraine). NPK fertilizers were applied at a dose, of 20, 80, and 80 kg ha<sup>-1</sup>, respectively. Before sowing, the seeds were inoculated with the microbial preparation BiNitro Chickpea (BN) and Biofosforyn (BF). Foliar feeding was carried out with the microfertilizer Freya–Aqua™ C(12) Legumes (F). The development of chickpea leaf area and the intensity of organic matter production were largely determined by the supply of the main macronutrients to the plants. The introduction of NPK significantly increased leaf area and net photosynthetic productivity, while the effect of BN, BF, and F on the values of these indices was not significant. Their effect was manifested during the accumulation of aboveground biomass and the formation of yield structure elements. An increase in the seed yield was shown in relation to the application of NPK, microbial preparations, and micronutrient fertilizers. Regardless of the NPK, the highest yield was shown in the variant of the combination of BN+BF+F.

Giant sequoia (Sequoiadendron giganteum) in the UK: carbon storage potential and growth rates.

Giant sequoias (Sequoiadendron giganteum) are some of the UK's largest trees, despite only being introduced in the mid-nineteenth century. There are an estimated half a million giant sequoias and closely related coastal redwoods (Sequoia sempervirens) in the UK. Given the recent interest in planting more trees, partly due to their carbon sequestration potential and also their undoubted public appeal, an understanding of their growth capability is important. However, little is known about their growth and carbon uptake under UK conditions. Here, we focus on S. giganteum and use three-dimensional terrestrial laser scanning to perform detailed structural measurements of 97 individuals at three sites covering a range of different conditions, to estimate aboveground biomass (AGB) and annual biomass accumulation rates. We show that UK-grown S. giganteum can sequester carbon at a rate of 85 kg yr-1, varying with climate, management and age. We develop new UK-specific allometric models for S. giganteum that fit the observed AGB with r 2 > 0.93 and bias < 2% and can be used to estimate S. giganteum biomass more generally. This study provides the first estimate of the growth and carbon sequestration of UK open-grown S. giganteum and provides a baseline for estimating their longer-term carbon sequestration capacity.

Soil water movement may regulate soil water consumption and improve cotton yields under different cotton cropping systems

By quantifying the soil water movement (SWM) in crop planting systems, we can better understand the soil water consumption (SWC) and crop yield relationship; this finding is significant for determining the field water cycle and reducing agricultural water waste. In this paper, a case study was conducted on cotton production. Soil moisture sensors were set at depths of 10–110 cm under three cotton cropping systems (monoculture cotton (MC), wheat/delayed intercropped cotton (WIC), and wheat/direct-seeded cotton (WDC)) based on spatial grid methods; a geostatistical grid calculus was used to calculate SWM; and the crop and meteorological influence mechanisms on cotton lint yield were comprehensively analyzed. At the squaring stage, SWC and vertical SWM were significantly correlated with light, temperature and water conditions. At the flowering and boll development stage, SWC and vertical SWM were collectively affected by meteorological conditions and crops, and they were positively correlated with lint yield. The aboveground and belowground biomass accumulation at the flowering and boll development stage positively affected vertical SWM in and between cotton rows. Vertical SWM in cotton rows increased SWC in cotton rows. SWC in cotton rows and aboveground biomass positively impacted lint yield formation; SWC between rows negatively impacted lint yield. The SWC and vertical SWM between rows in the MC seedling stage exceeded those in cotton rows, and more precise irrigation at the seedling stage reduced water waste. The WIC horizontal SWC at the squaring and flowering and boll opening stages was relatively high, moving from the row midline to cotton row. A better SWC distribution in and between cotton rows promoted water utilization in the cotton rows; this method was feasible for improving cotton yield in diverse planting systems. The results could optimize precision irrigation management at different cotton growth stages and provide a theoretical reference for promoting sustainable agricultural production and climate adaptation.

The metropolitan parks of Quito as important carbon sinks

Abstract Despite the importance of urban forests as important carbon sinks, studies in Ecuador have yet to assess their potential to store carbon. We assessed the carbon stored in the aboveground biomass (AGB) and annual rates of AGB accumulation in the Guangüiltagua Metropolitan Park (GMP) and the Southern Metropolitan Park (SMP). We installed 11 plots per park of 0.063 ha, where we surveyed all stems with a diameter at breast height (DBH) ≥2.5 cm. To estimate annual increments in AGB, we installed dendrometer bands on 10% of the total stems recorded in each plot (only in stems with ≥10 cm DBH). We measured the dendrometer band segment increase every 4 months from September 2019 to October 2020. Our results show that the GMP stores 171 ± 96 Mg C ha−1, significantly higher than the amount of carbon storage recorded in the SMP (100 ± 41 Mg C ha−1). In contrast, the GMP sequestered 3.30 ± 1.71 Mg C ha year−1, while the SMP sequestered an average of 4.45 ± 2.63 Mg C ha year−1. At the landscape scale, the SMP contains 0.072 Tg C (0.058–0.091, 95% CI), while the GMP contains a reservoir of 0.096 Tg C (0.067–0.13, 95% CI). Likewise, the AGB in the SMP 3,165 Mg C year−1 (2209–4297, 95% CI), while that in the GMP sequestered 1859 Mg year−1 (1361–2430, 95% CI). Our results show that the metropolitan parks of Quito are important carbon sinks and constitute essential elements in mitigating climate change in urban spaces.

Incorporating small‐scale disturbances in models of forest structure and aboveground biomass of tropical mountains

AbstractSeveral efforts have been made to model forest structure and estimate global aboveground biomass (AGB) magnitude and distribution. However, AGB models still show large uncertainties, especially over tropical mountains that are difficult to survey and understudied. Although forest disturbance and land use greatly influence forest structure and AGB accumulation, they are rarely considered in forest structure and AGB models. Including the effect of forest disturbance and land use could improve model performance. In this study, we used Landsat time series analysis and forest inventory data to assess and model the effect of small‐scale disturbance and land use on tropical montane forest structure and AGB. We explored two approaches: abrupt forest change detection, using the algorithm Breaks For Additive Seasonal Trend (BFAST), and gradual vegetation change by calculating the variation of remote sensing vegetation indices over time. We found that tropical montane landscapes are very dynamic and heterogenous. Out of the 284 forest plots analyzed, 27% had abrupt disturbances at least once between 1993 and 2014, and some of them showed abrupt disturbances several times. Forest plots with abrupt disturbances exhibit statistically significant lower basal area, tree height, and AGB than plots without abrupt disturbances. Using linear mixed‐effects models, we found that the number of breakpoints, annual Normalized Difference Vegetation Index SD, and Normalized Difference Water Index minimum values over time were the most informative variables for predicting forest structure, particularly basal area (adjusted R2 = 0.61). These variables are easy to calculate and could add significant power to forest structure and AGB models. In conclusion, incorporating small‐scale disturbance to model forest structure and AGB at regional scales is feasible through the identification of recent abrupt and gradual forest change using remote sensing time series. Including recent forest disturbance variables as predictors in forest structure models can greatly improve biomass predictability and mapping in dynamic landscapes.

Tropical dry forest response to nutrient fertilization: a model validation and sensitivity analysis

Abstract. Soil nutrients, especially nitrogen (N) and phosphorus (P), regulate plant growth and hence influence carbon fluxes between the land surface and atmosphere. However, how forests adjust biomass partitioning to leaves, wood, and fine roots in response to N and/or P fertilization remains puzzling. Recent work in tropical forests suggests that trees increase fine root production under P fertilization, but it is unclear whether mechanistic models can reproduce this dynamic. In order to better understand mechanisms governing nutrient effects on plant allocation and improve models, we used the nutrient-enabled ED2 model to simulate a fertilization experiment being conducted in a secondary tropical dry forest in Costa Rica. We evaluated how different allocation parameterizations affected model performance. These parameterizations prescribed a linear relationship between relative allocation to fine roots and soil P concentrations. The slope of the linear relationship was allowed to be positive, negative, or zero. Some parameterizations realistically simulated leaf, wood, and fine root production, and these parameterizations all assumed a positive relationship between relative allocation to fine roots and soil P concentration. Model simulations of a 30-year timeframe indicated strong sensitivity to parameterization and fertilization treatment. Without P fertilization, the simulated aboveground biomass (AGB) accumulation was insensitive to the parameterization. With P fertilization, the model was highly sensitive to the parameterization and the greatest AGB accumulation occurred when relative allocation to fine roots was independent of soil P. Our study demonstrates the need for simultaneous measurements of leaf, wood, and fine root production in nutrient fertilization experiments and for longer-term experiments. Models that do not accurately represent allocation to fine roots may be highly biased in their simulations of AGB, especially on multi-decadal timescales.

Does human intervention modulate the above-ground carbon biomass of agroforestry systems? A study of homegardens in Jaffna peninsula, Sri Lanka

CONTEXTAccumulating above-ground biomass (AGB) and conservation of biodiversity are two major services provided by any ecosystem and homegardens are no exceptions. The permanent structure of a homegarden is owing to its perennial tree-community which steadily builds up and maintains the tree diversity and AGB accumulation. Being a manmade agroforestry system, humans play a vital role in mediating each component of homegarden ecosystem including its carbon stock and biodiversity through management of the tree community. OBJECTIVEThe objectives of this study were to compute the tree diversity and AGB and human interventions in homegarden ecosystem in Jaffna peninsula and to identify the most prominent factors affecting the AGB. METHODSA primary survey was conducted capturing 135 homegardens from two agro-ecological regions (DL3 and DL4) in Jaffna peninsula (Northern province, Sri Lanka), where homegardens are observed as the primary tree-based vegetation. Data on floral composition, livestock and, household-interventions in homegardens were gathered through a structured questionnaire. Tree diversity and AGB were computed using Shannon-Wiener index (SWI) and carbon stock respectively. A multiple linear regression model was estimated to determine the effects of pre-defined interventions on AGB of homegardens. RESULTS AND CONCLUSIONSThe study sample consisted of 122 small-scale (<0.2 ha), 11 medium-scale (0.2–0.8 ha) and 02 large-scale (>0.8 ha) homegardens. The mean tree diversity as estimated by SWI was 1.1 ± 0.6 with 38 perennial species and 1286 trees; 32 genera and 17 families. An average homegarden is estimated to store 23.8 ± 20.9 Mg C/ha as AGB. Homegardens which reared livestock animals, had a significantly lower SWI value, yet, a higher AGB stock, compared to the opposed group (p < 0.05). The SWI, time allocation (hours) for homegarden/week/ha, technical knowledge on farming and non-timber usage within homegarden have significantly (p < 0.05) contributed to the AGB of homegardens, with regression-coefficients of 6.12, 0.02, 1.38 and 7.91, respectively. The results indicate that up-keeping the commitment of households in managing their homegardens contribute to environmental sustainability. SIGNIFICANCEThe results revealed a significant contribution of human interactions on the size of the AGB of homegardens in Jaffna peninsula. This contribution was not adequately discussed in previously literature and the findings suggest the need to manage human interactions in homegarden agroforestry systems to optimize carbon stock in traditional homegardens.

The effects of geomorphology, soil and climate on the trajectory of aboveground biomass accumulation of beech (Fagus sylvatica L.) at the southern range margin

Forest ecosystems are among the most important carbon sinks in the terrestrial biomes. Therefore, the estimation of aboveground biomass accumulation is of fundamental importance for understanding the contribution of forest stands to the global carbon budget. In this study, we proposed a modelling approach to estimate aboveground biomass of beech forests in the Central Apennine based on stand age, climatic variables, topographic features and soil parameters. Using forest inventory data from the local forest management plans, international databases, and mixed-effect linear model, we identified stand age as a major driver of beech forests aboveground biomass. Climatic variables had generally higher influence than soil and topographic features, probably as a consequence of the homogeneous calcareous substrate which favoured the development of soils which are highly suitable for the growth of beech. Temperature range and seasonality were the most important climatic variables. Interestingly, we found that the aboveground biomass in Apennine beech forests is strongly site-specific. Different management approaches during the past centuries, i.e. presence or absence of conversion interventions of the analysed stands, are probably responsible for the growing site's significant influence. By highlighting the ideal locations for allocating the functions of forest production or evaluating the value of ecosystem services that regulate the climate, this study will help to improve both the precision of carbon budget modelling and decision-making in nature conservation and forest management.

Влияние питательного субстрата на рост и распределение биомассы сеянцев Picea obovata Ledeb. в Северной Монголии

The development of seedling production technology and methods of establishing highyielding plantations of Picea obovata Ledeb. on a scientific basis is one of the urgent problems of forestry in Mongolia. In this study, we aimed to solve the following problems: to conduct a comparative analysis of the seedling growth parameters and biomass accumulation grown on different nutrient substrates; to assess the relationship between seedling growth, biomass accumulation and soil properties; to determine the most optimal nutrient substrates for seedling production of Siberian spruce in greenhouse conditions in Northern Mongolia. Six formulations of nutrient substrates (T1, Т2, Т3, Т4, Т5, Т6) were used for the seedling production of Picea obovata Ledeb. in greenhouses equipped with a sprinkler system. Nutrient substrates were prepared using black soil, manure, compost, peat, sawdust, sand in different composition ratios. During the 4-year-observation period height, root collar diameter, root length and aboveground and belowground biomass of seedlings were measured at the end of each growing season. We divided the biomass of seedlings into several structural elements. We found that all tested nutrient substrates, except the control substrate, had a positive effect on seedling growth in height and diameter. Comparative analyses showed that different ratio and composition of black soil, compost, manure, sawdust, and sand in the nutrient substrate had different effects on seedling growth (p &gt; 0.001) and biomass accumulation (p &gt; 0.001). Among the proposed nutrient substrates, the treatments T2 (50 % black soil + 20 % sand + 20 % peat + 10 % compost) and T6 (60 % black soil + 20 % sand + 10 % peat + 10 % compost) were selected as the most effective soil substrate that are suitable for further seedling production of Siberian spruce under greenhouse conditions in Mongolia. There fore, it was observed that good root system development was a determinant of seedling growth in height, diameter, and aboveground biomass accumulation especially from 3–4 years of age. Spruce seedling growth was positively correlated not only with humus content (r = 0.46), but also with soil acidity (r = 0.43) and available phosphorus (r = 0.48). The results of this investigation made an important contribution to the development of production technology for growing standard and large-sized seedlings of Picea obovata in greenhouse complexes in Northern Mongolia. For citation: Jagdag D., Batsaikhan G., Baatarbileg N., Lobanov A.I., Gerelbaatar S. Effect of Nutrient Substrate on Seedling Growth and Biomass Allocation of Picea obovata Ledeb. in Northern Mongolia. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 57–69. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-57-69

Increasing diversity gradient in lentil mixtures for intercropping with wheat reveals an increase in lentil biomass with minimal impact on mycorrhizal activity

The management of arbuscular mycorrhizal fungi (AMF) is crucial for sustainable agricultural systems, given its beneficial impacts on soil health and crop productivity. This study aimed to assess the effect of lentil (Lens culinaris Medik.) mixtures for intercropping with durum wheat (Triticum durum Desf.) on mycorrhiza and investigate the role of legume intraspecific diversity in mycorrhizal development and crop biomass production. Since both intraspecific and interspecific diversity (i.e., cultivar mixtures and intercropping) have an effect in shaping soil microbiota in the rhizosphere, we hypothesised that increasing the level of diversification in the system enhances the provision of services (e.g., aboveground biomass accumulation), due to enhanced microbial activity and diversity. Specifically, increasing diversity within lentil cultivar mixtures strengthens the affinity of wheat for mycorrhiza, thereby influencing wheat mycorrhization in wheat-lentil intercrops. To test our hypothesis, we designed three lentil cultivar mixtures with increasing diversity levels using a trait-based approach, drawing from a pool of Italian lentil landraces characterised in a previous study. As an additional factor, we intercropped lentil mixtures with wheat and compared it with sole wheat and sole lentil commercial cultivar. In both experimental years, intercropping lentil mixtures with wheat consistently yielded higher soil mycorrhization levels (46% in 2021 and 52% in 2022) compared to sole wheat cultivation (23% in 2021 and 34 % in 2022). Nevertheless, AMF colonisation in lentil roots was significantly higher in sole crops (55% in 2021 and 70% in 2022, except for the commercial cultivar) compared to intercrops (35% in 2021 and 60% in 2022). This difference could be attributed to the presence of wheat, which might have suppressed the capacity of lentils to establish successful symbiosis with mycorrhiza. On the other hand, AMF colonisation of wheat roots in 2022 was significantly higher (52%) when intercropped with lentils than when cultivated as sole wheat (40%). Concerning biomass production in lentil mixtures in 2022, we observed a positive correlation between lentil biomass and the number of functional groups in the mixtures, both as pure stands (R2 = 0.19, p = 0.06) and intercrops (R2 = 0.29, p = 0.01). Additionally, in 2022, the total biomass of the intercropped system increased with the increase in diversity. Further experiments, incorporating microbial genetic analysis, are necessary to uncover potential associations between functional mixtures and AMF composition.

Plant biotype interacting grazing activity shapes grassland ecosystem functions

AbstractGrasslands play an essential role in maintaining the health of planet Earth, but many grasslands have lost their ecosystem services due to unsustainable management practices, such as overgrazing. Little is known about how grazing activity interacts with plant biotypes, impacting grassland ecosystem services. Here, we (1) assessed the relative performance of five plant biotypes in response to grazing activities and (2) determined the effectiveness of grazing exclusion in enhancing soil physiochemical properties in grasslands. The synthesis of 39,214 observations on plant‐, soil‐, and anthropogeny‐related factors from 88 published studies revealed that grazing exclusion increased aboveground plant biomass accumulation by 100.4% (±4.2 SE), belowground biomass by 70.2% (±25.7), total soil C content by 21.4% (±1.7), and soil organic carbon (SOC) concentration by 14.3% (±0.8), on average, as compared to moderate‐to‐heavy (MtH) grazing. Plant biotypes responded to grazing activities differently; alpine meadows increased total soil C content by 107.2%, alpine steppes increased SOC by 52.2%, but desert steppes decreased total C content by 21.8% under the grazing exclusion. All plant biotypes reduced soil bulk density by 6.4%–19.4% under grazing exclusion. Soil microbial community diversity responded to grazing activities inconsistently, ranging from an 18% decrease to a 26% increase in soil microbial diversity compared to MtH grazing. We conclude that selecting appropriate plant biotypes alongside improved grazing management will enhance grassland ecosystem functions and services as plant biotypes affect aboveground and belowground biomass and interface with soil physiochemical properties.

Recovery of aboveground biomass, soil carbon stocks and species diversity in tropical montane secondary forests of East Africa

Tropical montane forests are fragile ecosystems that provide a wide range of ecosystem services including hydrological services, biodiversity protection and storing carbon in the above and belowground and soils contributing to climate change mitigation. The world’s tropical montane forests are increasingly exposed to degradation and their recovery after disturbance has not been adequately quantified. Here, using information from 47 plots in three blocks of the Mau Forest Complex of Kenya, we assessed the changes in aboveground biomass (AGB), tree species diversity, soil carbon and nitrogen stocks following forest clearance. AGB recovered at an annual rate of 6.42 Mg ha−1 yr−1 in the first 20 years, the rate then slowed down to 4.46–4.67 Mg ha−1 yr−1 at around 25–30 years. Around 25 years after disturbance, AGB in recovering forests was 70 % (198.32 ± 78.11 Mg ha−1) of the AGB in the old secondary forest (OSF) (282.86 ± 71.64 Mg ha−1) and was statistically indistinguishable. Stem density, species diversity and richness indices did not show significant differences across recovery classes. There was no significant difference in soil carbon and nitrogen stocks across classes with the soil carbon (184.1 ± 41 Mg ha−1) of the young secondary forest (<10 years) being 84.5 % of that of the OSF (217.9 ± 51.8 Mg ha−1). This study reports a rapid rate of AGB and carbon accumulation within 20 years of disturbance, and high levels of species richness in these previously disturbed fragments of tropical montane forests of East Africa.

Impacts of climate change on semi-natural alpine pastures productivity and floristic composition

Climate change impact on pasture floristic composition needs to be carefully assessed, given its key role for the resilience of pastoral systems and related ecosystem services. Nevertheless, variations in floristic composition are rarely taken into account in climate change impact studies. Here, we used the plant community model CoSMo to simulate future dynamics of biomass accumulation and floristic composition for high-altitude semi-natural alpine pastures. Dedicated multi-site field activities were conducted to collect data for model calibration. Simulations were run for four 20-year climate scenarios centered on 2040, resulting from the combination of two general circulation models (GISS-ES and HadGEM2) and two representative concentration pathways (RCP4.5 and RCP8.5). Results highlighted the capability of CoSMo to successfully reproduce the productivity and floristic composition of semi-natural pastures, modeling efficiency and R2 being higher than 0.90 for aboveground biomass accumulation and relative abundance of species. CoSMo simulated an overall positive effect of increasing temperatures on pasture productivity (+ 10.7% on average), due to higher biomass accumulation rates and longer growing seasons. However, these benefits were highly heterogeneous among the monitored pastures (ranging from − 2.5 to + 16.2%), because of differences in floristic composition and in species-specific thermal requirements that led to complex, non-linear reactions to climate variations. A negative impact of climate change was simulated for grazing value (− 11.1% on average), due to the higher suitability to future conditions of Nardus stricta, which has low grazing value compared to other species. Our results highlight that floristic composition should be explicitly considered while assessing climate change impacts on semi-natural pasture productivity and connected ecosystem services.

Sexual competition and light regimes interactively affect dimorphism and competitiveness of opposite sexes in Populus yunnanensis

Light, as the most important energy and environmental signal, exerts crucial impacts on plant-plant interactions and the composition of plant communities. However, little attention has been paid to understanding how females and males respond to sexual competition under different light conditions. In this study, we investigated morphological and physiological parameters between two sexes of Populus yunnanensis under intra- and intersexual competition in two light regimes, i.e., full light and shading conditions (equal to 55% full light). Under full-light conditions, males grown under intersexual competition exhibited greater above-ground biomass accumulation, specific leaf area (SLA), root-to-shoot ratio (R/S), non-structural carbohydrate (NSC) utilization efficiency, and a higher ability to maintain the balance of nitrogen (N) and phosphorus (P) content compared to females. These eco-physiological responses confer males with a competitive advantage over females under sufficient light conditions. In contrast, there were no significant sex-specific differences in biomass accumulation and relative competitive intensity (RCI) values under shade treatment. Under shading, the opposite sexes of P. yunnanensis exhibited mutual suppression of each other to varying degrees, showing similar competitive potential. These results demonstrate that the performance of plants in terms of morphology and physiology is strongly affected by patterns of sexual competition and light regimes. The asymmetry in sexual competition might be a crucial factor influencing the biased sex ratio of P. yunnanensis in natural habitats.

Estimating biomass of woody plants that grow in the different As-contaminated techno-soils in the ore-bearing provinces of Eastern Germany

Establishing the role of woody species as an instrument for heavy metal bioaccumulation is a relevant issue today in the context of the development of the phytoremediation system. The article presents the results of studies on the influence of different Arsenic (As) concentrations in soil on the development of aboveground biomass in Betula pendula Roth. and Populus tremula L. stands under conditions of reclamation plantings. The studies were conducted in 30 locations of birch and poplar tree plantations within the ore-producing regions of Saxony (Eastern Germany) in soil with different levels of As contamination. The highest As content was noted in the technosoil of the Davidschacht site, where the metalloid content was 229.3 times greater compared with a value in a conditionally uncontaminated area (Großschirma). The values of leaf area index and aboveground biomass obtained in field measurements were presented. The aboveground biomass values in the investigated plantations ranged from 189.9 ±10.16 to 201.8 ± 19.09 t/ha, and leaf area index values ranged from 1.74 ± 0.29 to 2.05 ± 0.16 m2/m2. Sentinel-2A multispectral images were processed for the construction of a map of the aboveground biomass distribution within the region under study. The values of the spectral indices for leaf area index were obtained with subsequent construction of the regression dependence of the aboveground biomass in the plantings on this indicator. The RMSE value for the developed model of the dependence of aboveground biomass on the leaf area index was 17.84 t/ha, which could be considered as satisfactory and can serve as a basis for practical application of the model developed. The inverse trend in relation to locations with different levels of soil contamination with As was determined for the aboveground biomass indicator. Within the region under study, the highest value of aboveground biomass in the stands was found for the area with the lowest As level. The results showed that the correlation coefficient between the highest of the optimal spectral indices, the leaf area index, and the aboveground biomass in B. pendula and P. tremula plantings was statistically significant and approached the value of 0.7. The results presented can become a theoretical basis for monitoring the accumulation of aboveground biomass of tree stands in areas with different levels of soil contamination with As. In perspective, the presented model of biomass estimation based on spectral technologies can serve as an application basis for rapid assessment of the growth and development parameters of forest stands in As-contaminated areas.

Low predictability in aboveground biomass accumulation in Brazilian semi‐deciduous seasonal Atlantic Forest restoration sites

There are high expectations about the role of active reforestation in mitigating climate change, by means of carbon sequestration and storage, fueling the carbon credit market. Carbon credits are calculated in advance based on the number of planted trees or, at best, the expected size and wood density of planted trees. However, the contribution of tropical reforestations with native species for carbon sequestration in the long term is still unclear, since most sites being monitored are less than 20 years old, thus limiting the ability to make forecasts of what is a dynamic, multifactor restoration outcome. We used a chronosequence to analyze aboveground biomass (AGB) accumulation in 30 Brazilian semi‐deciduous seasonal Atlantic Forest restoration sites sharing the same climate, soil type, and restoration technique. We evaluated the entire age range of 1–19 years, and three age intervals, 1–3 years, 4–8 years, and over 9 years. AGB, basal area, and tree density increased considering all ages (1–19 years). Our results showed, however, that the AGB, tree density, and basal area can increase linearly from 1 to 3 years but present no significant trend after 4 years. Adjusted model r2 values decreased with time, suggesting that the controlled effects of active restoration are quickly replaced by other natural, uncontrolled, and, to some extent, unknown factors. Although continued efforts are needed to make more realistic predictions of long‐term carbon stocks based on tree planting, high levels of biomass estimates for time intervals as short as 20 years may never be achieved.