Ecosystem Carbon Sequestration Research Articles

Structural diversity as a reliable and novel predictor for ecosystem productivity

The physical structure of vegetation is thought to be closely related to ecosystem function, but little is known of its pertinence across geographic regions. Here, we used data from over three million trees in continental North America to evaluate structural diversity – the volumetric capacity and physical arrangement of biotic components in ecosystems – as a predictor of productivity. We show that structural diversity is a robust predictor of forest productivity and consistently outperforms the traditional measure – species diversity – across climate conditions in North America. Moreover, structural diversity appears to be a better surrogate of niche occupancy because it captures variation in size that can be used to measure realized niche space. Structural diversity offers an easily measured metric to direct restoration and management decision making to maximize ecosystem productivity and carbon sequestration.

Korelasi indeks keanekaragaman dan kerapatan tegakan dengan simpanan karbon mangrove Estuari Perancak

Land use change is a huge threat for mangrove ecosystems,which are known for their high carbon sequestration and storage capacity.Vegetation restoration efforts are often undertaken, but fail to restore optimal ecosystem carbon sequestration. The mangrove forest of Perancak Estuary with a history of restoration project was made the subject of this research. The objectives include: (i) estimation of mangrove biomass and sediment carbon stock; (ii) comparison of restored, mixed and natural mangroves’ total carbon stock; (iii) correlational analysis between stand density and diversity indices with ecosystem carbon stock. Nine sampling points were determined within three mangrove categories (mixed, natural, restored). Stand characteristics and diameter at breast height (DBH) were measured to allometrically estimate biomass carbon. Sediment carbon was analyzed with Loss on Ignition (LOI) method. Correlational analysis was done with Pearson’s correlation coefficient. Total ecosystem carbon stock is 4472,93 tonnes ha-1 (biomass C: 4046,31 tonnes ha-1; sediment C: 426,62 tonnes ha-1). Highest carbon stock value was found on restored mangroves due to high contribution of sediment C offsetting its low biomass C. Lowest carbon stock value was found on natural mangroves due to decreased root biomass production and increased decomposition due to change in tidal regimes. There is a strong positive correlation between stand density and biomass carbon. Simpson index of diversity has a stronger (though non significant) correlation with biomass carbon than Shannon-Wiener index.

Ecosystem carbon sequestration service supports the Sustainable Development Goals progress

Ecosystem carbon sequestration service (ECSS) is the benefits humans derive from the ecosystem carbon sequestration process, which is key to regulating climate, stabilising the natural foundation for development, and supporting the Sustainable Development Goals (SDGs) achievement. However, how ECSS contributes to the SDGs still needs to be discovered. Here, based on downscaling localisation SDG indicators, regression methods, and mechanism analysis, we identified the contribution of ECSS to the SDGs, taking China's Loess Plateau (LP) region as an example. The results showed that the LP made higher progress on resource and environmental SDGs, such as SDGs 13, 12, 6, and 7 (climate, consumption and production, water, and energy) in the last two decades. As for the relationships between ECSS and SDGs, the progress of SDGs 6, 7, 13 and 15 (water, energy, climate, and ecosystems) showed positive linear responses to ECSS. The response of SDGs 1, 4, 8, and 12 (poverty reduction, education, economic growth, and consumption and production) to ECSS showed a threshold when the standardised ECSS value was 0.11. To improve ECSS for a more sustainable ecological foundation underpinning the SDGs, ECSS management should be improved to protect the ecosystem carbon pool and improve carbon sequestration function, as well as to promote the social-ecological co-benefits. This work links carbon sequestration service to sustainable development and can help in leveraging nature's contributions towards carbon neutrality and the 2030 Agenda.

“双碳”目标下山水林田湖草沙一体化保护和修复工程优先区与技术策略研究

PDF HTML阅读 XML下载 导出引用 引用提醒 “双碳”目标下山水林田湖草沙一体化保护和修复工程优先区与技术策略研究 DOI: 10.5846/stxb202201280266 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划(2019YFC0507804);2019年度自然资源部科技创新人才培养工程青年人才资助项目(12110600000018003931) Research of priority areas and technical strategies of the integrated protection and restoration projects for full-array ecosystems with carbon peak and carbon neutrality goals in China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:巩固与提升生态系统碳汇能力是实现碳达峰、碳中和目标的重要途径之一。生态保护修复对生态系统固碳增汇有着重要影响。2016-2021年,财政部、自然资源部、生态环境部在我国27个省(自治区、直辖市)共支持了三批山水林田湖草生态保护修复工程试点和第一批山水林田湖草沙一体化保护和修复工程,共35个山水工程。通过分析已部署的35个山水工程布局的空间特征和碳汇效益,结合国家重点关注的生态保护修复区域、全国重要生态系统保护和修复重大工程分布、生态系统碳汇重要区域和敏感区域,探索"双碳"目标下山水工程布局优先区及生态保护修复技术策略。研究发现山水工程的碳汇效益具有空间差异性,且山水工程优先区主要依次分布在青藏高原生态屏障区、东北森林带、长江重点生态区(含川滇生态屏障)、南方丘陵山地带、黄河重点生态区(含黄土高原生态屏障)、北方防沙带等的森林、高原草地、荒漠、岩溶地区等区域。基于此,提出未来山水工程在不同区域的技术策略。在森林生态系统为主地区,不仅要提高森林覆盖度、森林质量,还应当加强生物多样性的保护和土壤碳汇能力的提升;在高原草原及冻土地区应加强草地退化和冻土监测,提高草地质量;在西北荒漠化地区加强碳汇理论技术研究;另外还需加强喀斯特地区双重碳汇效应。因地制宜、取长补短,有针对性地对不同生态系统改善碳汇能力,不仅有助于实现双碳目标,也有利于提升生态保护修复工程的效益。 Abstract:The promotion of ecosystem carbon storage and sequestration play an important role in achieving carbon peak and carbon neutrality goals. Ecological protection and restoration have profound effects on carbon sequestration in ecosystems. During 2016 to 2019, the related ministries have arranged a total of 35 projects, including three batches of ecological protection and restoration pilot projects and the first batch of integrated protection and restoration projects, across 27 provinces. We analyzed the spatial pattern of ecological protection and restoration projects and its effects on the ecosystem carbon sequestration capacity, and identified the important and sensitive areas of ecosystem carbon sequestration. Considering ecological protection and restoration areas that were highly concerned by the nation, and distribution of major projects for the protection and restoration of important national ecosystems, we explored the priority area and technical strategies of integrated protection and restoration projects of full-array ecosystems under carbon peak and carbon neutrality goals. We found that the changes of ecosystem carbon sequestration in the zone of 25 pilot projects varied with regions. The priority areas were mainly distributed on the Qinghai-Tibet Plateau ecological barrier area, the northern sand prevention belt, the key ecological areas along the Yangtze River, and hilly area in South China where mostly covered by forest, plateau grasslands, deserts, karst areas etc. Accordingly, we proposed technical strategies for the restoration projects in different regions. In forest ecosystem areas, we should not only improve coverage and quality of forest, but also strengthen biodiversity protection and soil carbon sink capacity. In plateau grassland and frozen soil areas, the monitoring of grassland degradation and frozen soil are essential to improve the land quality. In the desertification area of Northwest China, we should focus more on the research of carbon sink theory and technology. In karst areas, the dual carbon sink effect is the key factor which should be taken seriously. The incremental improvement of carbon sinks for different ecosystems according to local conditions will not only help achieve the dual-carbon goal, but also help improve the benefits of ecological protection and restoration projects. 参考文献 相似文献 引证文献

Multi-year throughfall reduction enhanced the growth and non-structural carbohydrate storage of roots at the expenses of above-ground growth in a warm-temperate natural oak forest

The more frequent occurrence and severer drought events resulting from climate change are increasingly affecting the physiological performance of trees and ecosystem carbon sequestration in many regions of the world. However, our understanding of the mechanisms underlying the responses and adaption of forest trees to prolonged and multi-year drought is still limited. To address this problem, we conducted a long-term manipulative throughfall reduction (TFR, reduction of natural throughfall by 50%–70% during growing seasons) experiment in a natural oriental white oak (Quercus aliena var. acuteserrata Maxim.) forest under warm-temperate climate. After seven years of continuous TFR treatment, the aboveground growth in Q. aliena var. acuteserrata started to decline. Compared with the control plots, trees in the TFR treatment significantly reduced growth increments of stems (−14.2%) and leaf area index (−6.8%). The rate of net photosynthesis appeared to be more susceptible to changes in soil water in trees subjected to the TFR than in the control. The TFR-treated trees allocated significantly more photosynthates to belowground, leading to enhanced growth and nonstructural carbohydrates (NSC) storage in roots. The 7-year continuous TFR treatment increased the biomass, the production and the NSC concentration in the fine roots by 53.6%, 153.6% and 9.6%, respectively. There were clear trade-offs between the aboveground growth and the fine root biomass and NSC storage in Q. aliena var. acuteserrata trees in response to the multi-year TFR treatment. A negative correlation between the fine root NSC concentration and soil water suggested a strategy of preferential C storage over growth when soil water became deficient; the stored NSC during water limitation would then help promote root growth when drought stress is released. Our findings demonstrate the warm-temperate oak forest adopted a more conservative NSC use strategy in response to long-term drought stress, with enhanced root growth and NSC storage at the expenses of above-ground growth to mitigate climate change-induced drought.

Soil moisture shapes the environmental control mechanism on canopy conductance in a natural oak forest.

Canopy conductance (gc) is an important biophysical parameter closely related to ecosystem energy partitioning and carbon sequestration, which can be used to judge drought effect on forest ecosystems. It is very important to explore how soil moisture change affects the environmental control mechanism of gc, especially in natural oak forests in Central China where frequent extreme precipitation (P) and drought will occur in a context of climate change. In this study, variations of gc and its environmental control mechanisms in a warm-temperate forest over three consecutive years under different hydroclimatic conditions were examined by using eddy-covariance technique. Results showed that the averaged gc in the three growing seasons were 11.2, 11.3 and 7.8 mms-1, respectively, with a CV of 19.7 %. The lowest gc occurred in the year with the lowest P. Using three years of data, we found that vapor pressure deficit (VPD) exhibited the dominate effect on gc, both diffuse photosynthetically active radiation (PARdif) and air temperature (Ta) were positively correlated with gc. When relative extractable water content (REW) was larger than 0.4, however, inhibiting effect of high VPD on gc disappeared and the effect of direct photosynthetically active radiation (PARdir) on gc was larger compared to PARdif. When REW was <0.1, the positive relationship between Ta and gc became negative. Our results indicated that soil moisture ultimately shapes the environmental control mechanism of gc in a natural oak forest.

Evaluation of Biogeochemical Changes in Channelized and Restored Portions of a Subtropical Floodplain

Floodplains are critically important ecosystems that provide a whole suite of ecosystem services, including nutrient and carbon sequestration, flood mitigation, water storage, and critical wildlife habitat. However, human modification of rivers and floodplains through channelization, artificial levee construction, reductions in the active floodplain area, and water management can significantly reduce the ecosystem function of river–floodplain systems. In this study, we evaluated the changes in the nutrient loading of the Kissimmee River floodplain during the restoration of the river–floodplain system. In addition to time-series loading analysis, we also evaluated soil nutrient concentrations across the lower portion of the Kissimmee River floodplain. During the 44-year nutrient loading time-series, the floodplain remained a nutrient exporter with changes in nutrient loading generally corresponding to both water quality (i.e., point source reductions) and hydrologic restoration activities in the watershed and Kissimmee River floodplain. During the study period, inputs of total phosphorus and total nitrogen loads from upstream either significantly increased or remained the same. In addition to external sources of nutrients, internal sources of nutrients from floodplain soils can also contribute to the total nutrient export from the system. These internal sources could be organic via the decomposition of organic matter or geologic from the original excavation of the canal and/or restoration backfilling. Soil nutrient concentrations vary between vegetative communities and landscape position and could be a significant source of phosphorus to the downstream system, which is plagued by eutrophic conditions. Therefore, as floodplain function in the Kissimmee River continues to be restored and managed, additional effort may be needed to address nutrient inputs and internal legacy nutrients.

A research agenda for nonvascular photoautotrophs under climate change.

Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2 , (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.

Quantifying the benefits of reducing synthetic nitrogen application policy on ecosystem carbon sequestration and biodiversity

Synthetic Nitrogen (N) usage in agriculture has greatly increased food supply over the past century. However, the intensive use of N fertilizer is nevertheless the source of numerous environmental issues and remains a major challenge for policymakers to understand, measure, and quantify the interactions and trade-offs between ecosystem carbon and terrestrial biodiversity loss. In this study, we investigate the impacts of a public policy scenario that aims to halve N fertilizer application across European Union (EU) agriculture on both carbon (C) sequestration and biodiversity changes. We quantify the impacts by integrating two economic models with an agricultural land surface model and a terrestrial biodiversity model (that uses data from a range of taxonomic groups, including plants, fungi, vertebrates and invertebrates). Here, we show that the two economic scenarios lead to different outcomes in terms of C sequestration potential and biodiversity. Land abandonment associated with increased fertilizer price scenario facilitates higher C sequestration in soils (+ 1014 MtC) and similar species richness levels (+ 1.9%) at the EU scale. On the other hand, the more extensive crop production scenario is associated with lower C sequestration potential in soils (− 97 MtC) and similar species richness levels (− 0.4%) because of a lower area of grazing land. Our results therefore highlight the complexity of the environmental consequences of a nitrogen reduction policy, which will depend fundamentally on how the economic models used to project consequences.

Carbon sequestration characteristics of two plantation forest ecosystems with different lithologies of karst.

In karst regions, the majority of studies have focused on ecosystem carbon sequestration in the same lithology, but no studies in different lithologies. In this study, actual measurements were used to reveal carbon sequestration characteristics of two plantation forest ecosystems (Bodinieri cinnamon and Cupressus funebris) with different lithologies of karst. The results showed that the tree layer showed the highest vegetation biomass, carbon content, carbon density, and ratio of aboveground biomass to belowground biomass. The carbon density of B. cinnamon plantation and C. funebris plantation was high in dolomite and in limestone respectively. The soil quality and carbon density of bare ground and plantation varied across different lithologies. The carbon density of various ecosystem components was in the order of vegetation>soil>litterfall. The carbon density and net carbon density of plantation varied across different lithologies. In B. cinnamon plantation, the carbon sequestration rate of vegetation and ecosystem was high in dolomite, moderate in limestone, and low in dolomitic sandstone. In Cupressus funebris plantation, the carbon sequestration rate was in the order of limestone>dolomite>dolomitic sandstone. These findings revealed that lithology is an important factor affecting ecosystem carbon pools, and plantation ecosystems have low biomass and low carbon density in karst areas.

Ecosystems in a State of Flux: Evidence from A Kenyan Coastal Riparian Ecosystem

Riparian ecosystems are considered hotspots of carbon and nitrogen transformations. These biochemical transformations are driven by anthropogenic activities in the immediate riverine water catchments. The anthropogenic activities may include and not limited to extraction of goods such as agricultural products, wood products, honey, plant based pharmaceutical products, livestock products, firewood, water and grass for thatching homesteads. Riparian ecosystems also provide important tangible and intangible ecosystem services comprising spiritual and aesthetic functions, pollination, ecosystem detoxification functions, carbon and nitrogen sequestration and CO2 sinks for amelioration of climate change impacts among others. These ecosystems are increasingly threatened by degradation attributed to land use changes. Human perturbations such as crop farming on riparian land, overgrazing and population pressure on land resources influence degradation of riparian ecosystems, with profound effects on biodiversity conservation and local livelihoods. Evidence from the literature indicates that although there is a general understanding regarding the response of terrestrial and wetland ecosystems to human perturbations, there is a dearth of information on the response of African riparian ecosystems to ecologic and socio-economic impacts.

Responses of carbon dynamics to grazing exclusion in natural alpine grassland ecosystems on the QingZang Plateau.

In the context of "Carbon Emissions Peak" and "Carbon Neutrality", grazing exclusion (GE) has been applied widely to rehabilitate degraded grasslands and increase carbon sequestration. However, on the QingZang Plateau (QZP), the impacts of GE on the carbon dynamics of alpine grasslands are poorly understood, particularly at a regional scale. To fill this knowledge gap, we evaluated the responses of carbon sequestration to GE in different alpine grasslands across QZP by using meta-analysis. The effects of GE on ecosystem carbon fractions were dependent on GE duration, grassland types and climate factors. Specifically, our results indicated that GE had more obviously positive effects on carbon stock across the alpine meadow than the alpine steppe. However, when considering different GE duration, the longer duration of GE was more effective for increasing ecosystem carbon sequestration (R 2 = 0.52, P<0.0001) in the alpine steppe. Our results further demonstrated that annual mean precipitation (AMP) and temperature (AMT) began to dominate ecosystem carbon sequestration after three years of GE duration across the alpine meadow; and AMP was an important climate factor limiting ecosystem carbon sequestration (R 2 = 0.34, P<0.01) in the alpine steppe. In terms of plant carbon fraction, GE generated continuous positive effect (P<0.05) on aboveground biomass with the increased GE duration in the alpine meadow, while this positive effect disappeared after the 8th year of GE duration. And no positive effects were found on belowground biomass in the 11th year in alpine steppe. For soil organic carbon (SOC), there existed periodic fluctuations (increased and then decreased) on SOC in response to GE. For microbial biomass carbon, there were no obvious trends in response to GE duration. In general, we highlighted that the responses of different carbon fractions (plant-soil-microbe) to GE were non-uniform at spatial and temporal scales, thereby we should adopt different carbon management practices for sustainable development of different grasslands.

Soil organic carbon sourcing variance in the rhizosphere vs. non-rhizosphere of two mycorrhizal tree species

Soil organic carbon (SOC) plays a central role in ecosystem carbon sequestration and climate change mitigation, and its stability and dynamics are related to sourcing from microbial vs. plant residues. However, SOC sourcing and its regulating mechanisms remain poorly understood in soil's most bioactive compartment, the rhizosphere, which may differ from non-rhizosphere and under different mycorrhizal tree species. To fill the knowledge gap, here we collect the rhizosphere and non-rhizosphere soils under an arbuscular mycorrhizal (AM; Castanopsis eyrie) vs. an ectomycorrhizal (ECM) tree species (Pinus massoniana) of varied tree diameters (i.e., ages) in the Gutianshan subtropical forest of China. Plant and microbial residual components are quantified by lignin phenols and amino sugars, respectively. Coupled with the measurements of soil, microbial community and plant litter properties, we assess potential mechanisms (i.e., saprotrophic bacteria competition, microbial necromass recycling/reuse, and substrate quality control) influencing the distribution of plant and microbial residues in the rhizosphere vs. non-rhizosphere. We show that lignin phenols are more concentrated in rhizosphere than non-rhizosphere SOC, especially under the ECM trees showing inhibited saprotrophic decomposition induced by competition between ECM fungi and (saprophytic) bacteria. Amino sugars are also more concentrated in the rhizosphere of ECM trees due to ECM fungal contribution, but not under AM trees exhibiting reduced fungal necromass stability partially reflected by low biomass-normalized necromass accumulation coefficients in the rhizosphere. As a result, ratios of amino sugars to lignin phenols are relatively lower in the rhizosphere than non-rhizosphere under AM tree, challenging the presumed microbial dominance in rhizosphere carbon accumulation. These results highlight differences in and controls on rhizosphere SOC sourcing related to different mycorrhizal tree species, providing new information on the mechanisms regulating soil carbon dynamics in root-soil systems.

Total ecosystem blue carbon stocks and sequestration potential along a naturally regenerated mangrove forest chronosequence

Naturally regenerated (NR) mangroves offer an excellent passive approach for climate change mitigation and adaptation under UN decade of restoration program. However, the support of NR mangroves on total ecosystem carbon (TEC) stocks and sequestration potential remained unclear across forest stand development process that can significantly vary spatially and temporally due to regeneration age. Using the ‘space for time’ approach, this study quantified the TEC stocks along the Merlimau - Kuala Sebatu fringing mangrove habitat expansion chrono-sequence that comprised of 3, 6, 12, 18, 25 years age and intact stands. We also estimated the carbon (C) sequestration potential of each stand-age by comparing with un-vegetated mudflats as control. We collected aboveground tree, belowground root, downed woody debris, litterfall and soil core up to 2 m for TEC quantification and C sequestration. Mean TEC stocks ranged from 232 ± 69 to 296 ± 49 Mg C/ha for NR3 and NR25 respectively at the study area. TEC stocks from different aged NR and intact mangroves were not significantly different from each other and therefore did not affect by age. Aboveground trees C and downed wood C pools were significantly affected by stand-age. In contrast, sediment C stocks (representing up to 80 %) remained generic over many years, driving the constant of TEC stocks in this study. Equally affected by age, the NR mangroves sequestered total C of 2.28 to 17.38 (mean ± SE: 7.36 ± 1.88 Mg C/ha yr−1), with younger stands (NR3) holding almost six times higher total C sequestration rates than older mangroves (NR25). Our study suggests that highly suspended sediments driving from upstream, especially in the younger mangrove stands at a lower elevation, supports higher bulk density and C accumulation rate in the sediment as they expand seaward. This study proves that NR mangroves comprised primarily of younger mangrove stands can be a C sequestrator powerhouse that promises nature-based climate solutions through avoidance and management. Though, future research is needed to understand how better management and conservation practices can affect or towards increasing trend of TEC especially sediment carbon stock that holds almost 80 % of total TEC.

Dynamic traceability effects of soil moisture on the precipitation–vegetation association in drylands

Vegetation growth is critical in characterizing ecosystem carbon sequestration. Water availability profoundly affects the interaction between climate change and vegetation dynamics in drylands. However, the associations of the precipitation–vegetation index (PRE-VI) and temperature–vegetation index (TEM-VI) as well as whether and how the soil moisture modulates PRE-VI and TEM-VI are still unclear. Precipitation contributed substantially much more to vegetation dynamics than temperature, and PRE-VI associations were greater in the Southern Hemisphere than those in the Northern Hemisphere in global drylands. The traceability effects of soil moisture on PRE-VI and TEM-VI were investigated, and a convex shape was observed for PRE-VI as soil moisture increased, but not significant trend for TEM-VI. It showed that moderate soil moisture enhanced PRE-VI associations through the maintenance of reasonable surface–atmosphere feedback to counteract the balance of plant growth and energy collocation. In the past three decades, PRE-VI associations decreased with the increase in soil moisture, suggesting the consistency of the spatial and temporal pattern of the effect of soil moisture on PRE-VI associations in water-limited ecosystems. Our results implied that changes in soil moisture reflect changes in climate–vegetation associations and can guide nature-based solutions to improve ecosystem carbon sink.

Impact of agriculture intensification on forest degradation and tree carbon stock; promoting multi‐criteria optimization for restoration in Central India

AbstractForest conservation entails both halting destruction and protecting the state of the forest's vegetation. Monitoring forest cover and restoring degraded forests are critical ecological aspects for India's forestry sector's long‐term growth. Cropland expansion and intensification are the primary approaches for increasing agricultural productivity in response to increased biomass demand, but they are also major drivers of biodiversity loss. We evaluated the ecosystem carbon (C) stock and sequestration potential for dry deciduous forests while assessing the drivers of forest degradation in Central India to advance scientific knowledge and minimize the anthropogenic C emissions from prevalent agriculture intensification in the region. A multi‐criteria optimization approach was used to identify the priority areas forrestoration and quantify the magnitude of drivers of biodiversity loss in the region by investigating the links between forest carbon stock, agriculture intensification, and altering forest structure at various degrees of forest disturbance. The total existing carbon stock of trees in study area during March 2020, was 199.12 Mg C ha−1. Overall carbon stock of these forests showed a significant correlation with disturbance levels (r = 0.50). Changes in vegetation especially to intensive agriculture practices have resulted in loss of carbon stocks and will cause large‐scale forest decline if not addressed immediately. Considering the rapid loss of forests in situation where India has to fulfill Nationally Determined Contributions to UNFCCC, Forest Landscape Restoration becomes priority and needs specialized efforts with enhanced funding to reduce and halt loss of forests.

Stomatal Limitation Is Able to Modulate Leaf Coloration Onset of Temperate Deciduous Tree

Autumn phenology, determined mainly by temperature and photoperiod, is essential for ecosystem carbon sequestration. Usually, the variations in the maximum rate of Rubisco (Vcmax) and the maximum rate of ribulose-bisphosphate regeneration (Jmax) are taken as the mechanism regulating the seasonal pattern of photosynthetic rates and autumn phenology. In this study, we used Quercus mongolicus seedlings as an example to examine the photosynthetically physiological mechanism of leaf coloration onset (LCO) responding to different warming and photoperiod treatments based on experimental data acquired from large artificial climate simulation chambers. The results indicated that: (1) LCO and the net CO2 assimilation rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), Vcmax, and Jmax of Quercus mongolicus seedlings were significantly affected by the changes of photoperiod. (2) LCO was significantly correlated only with the Pn approach, supporting the view that leaf senescence is the result of a trade-off between nutrient resorption and reserves. (3) The major variation in stomatal conductance (Gs) is the mechanism by which photoperiod regulates the seasonal pattern of photosynthetic rates, implying that both limitations of stomatal and photosynthetical capacity (Vcmax and Jmax, non-stomatal limitation) are able to modulate LCO. Our study riches the knowledge of phenology and provides a reference for phenological modelling and ecosystem carbon estimation.

On the link between tree size and ecosystem carbon sequestration capacity across continental forests

AbstractThe asymptotic height (Hmax) and the size‐scaling exponent (β), proxies of tree size and important forest architectural parameters of the relationships between height and tree diameter of forests, play important roles in the carbon (C) stocks and fluxes of forest ecosystems. However, the patterns and drivers of these values in continental China are not well known. Based on a national forest database of China, we explored the geographic patterns and ecological drivers of Hmax and β and their dynamic relationships with the C sequestration capabilities of the studied ecosystems, including the C stock and allocation, net ecosystem productivity (NEP), and mean ecosystem C turnover time. At the ecosystem scale, the Hmax values ranged from 10.37 to 37.07 m, with a mean value of 25.41 m, showing a decreasing trend with increasing latitude. However, β ranged from 0.598 to 0.73, with a mean value of 0.66, showing an increasing trend with latitude. The spatial patterns of the forest Hmax and β at the national scale were largely controlled by the mean annual temperature, mean annual precipitation, and forest age. These patterns were verified using biomass and forest C sequestration data, showing that the total vegetation C stock as a whole, in aboveground or belowground components, was significantly and positively correlated with Hmax (p &lt; 0.05), revealing apparent “faster first, slower later” increasing trends with Hmax (R2 = 0.759, 0.821, and 0.527, respectively). In addition, for forest &gt;20 m, NEP showed a significant strong negative correlation with Hmax (by −0.967% per 1 m of Hmax, R2 = 0.504, p &lt; 0.05), and a 10‐m increase in Hmax resulted in a decrease in mean ecosystem C turnover time by 16.9% (7.43 years). Taller forests might indeed be expected to have higher autotrophic respiration consumption rates but lower mean ecosystem C turnover time and NEP values than shorter forests. The discovery that community‐level asymptotic height could be used as a comparative predictor of ecosystem C sequestration capacity and its difference among forest biomes underpins the fundamentals of ecological theories and modeling, which has important implications for forest restoration, policy, and management.

Projected global warming-induced terrestrial ecosystem carbon across China under SSP scenarios

Terrestrial ecosystem carbon sequestration is one of the most economically feasible and important ways to mitigate the increase of atmospheric CO2 concentration. China's terrestrial ecosystems have a huge carbon sequestration potential. Therefore, the study on the carbon sequestration potential of vegetation ecosystems is related to the smooth implementation of China's carbon neutrality strategy in 2060. Based on the CMIP6 shared socioeconomic pathways (SSPs) scenarios, changes in the vegetation aboveground biomass carbon (ABC) were estimated using the Lund–Potsdam–Jena Dynamic Global Vegetation Model (LPJ) model (1981–2060) for China. Subsequently, the vegetation ABC dynamics were analyzed under three future scenarios based on the traditional Multi-Model Ensemble Mean (MME) method for different eco-regions in China. We found that the vegetation ABC density was 32.38 Mg/ha in China with an increasing trend of 53.99% from 1981 to 2014. The vegetation ABC density was higher in sub-regions I, II, V, and VI. Due to the main forest carbon sinks was appeared in Southwest, Northeast and Southeast of China. However, the water conditions are poor in sub-regions III, VII, and VIII, and mostly covered by desert and steppe vegetation where the productivity level is low. Under SSP1-2.6 and SSP2-4.5 scenarios, the vegetation ABC would show a decreasing trend from 2015 to 2040 with a reduction rate of 4.34% and 4.60%, but exhibit an increasing trend from 2041 to 2060 with a growth rate of 1.46% and 0.97%. While the vegetation ABC would show a decreasing trend during 2015 to 2060 with a reduction rate of 14.78% under SSP5-8.5 scenarios. Additionally, temperature and precipitation are main factors influencing the vegetation ABC. In the future scenario, due to higher temperatures resulted in the decrease of vegetation ABC in the cold temperate humid and temperate humid/sub-humid regions. However, in the northwestern arid region and Qinghai-Tibet Plateau region may have been due to relatively low temperatures in the region, warming may address this limitation and lead to a general increase in ABC.

Contributions of competition on Larix kaempferi tree-ring growth were higher than long-term climate in China

Forest tree growth plays an important role in forest ecosystem carbon cycle and carbon sequestration, and tree growth is affected by many factors. However, information on the contribution rate of different factors to tree growth is still limited. Thus, we hypothesized that increased regional competition has a significant negative impact on tree growth in plantations. In order to ascertain this hypothesis, tree-rings width for developing chronologies and competition data of the Larix kaempferi in Chinese plantations were sampled. Using tree-ring climatology method and non-linear models based on maximum likelihood analysis etc., the relationship between the tree-ring growth and competition index and climatic factors and their relative importance were evaluated in different years-interval and climate-zone. The results showed that the competitive effect for trees growth was always much stronger than the climatic or size effect. Competitive effects change over time, with drought effects (vapor pressure deficit (VPD) and standardized precipitation-evapotranspiration index (SPEI)) on tree growth exacerbated. The significant negative effects of neighborhood competition gradually increased over time. Climate moderates competitive effects during stand development, especially the negative effects of drought index on trees. Trees decline in growth due to climate warming with temperature and precipitation changes, and mainly, increased competition. Overall, these results constitute important new information, which not only further deepens our understanding of important theoretical issues related to plantation tree growth, but also helps to formulate new guidelines to make larch plantations adapt to global changes. Therefore, thinning measures are valuable suggestions to change forest density can promote trees growth, it provides highly valuable information for estimating future forest dynamics and changes in carbon storage and carbon neutrality under climate change.