Belowground Biomass Research Articles

Isolation and evaluation of Qatari soil rhizobacteria for antagonistic potential against phytopathogens and growth promotion in tomato plants

Plant growth promoting rhizobacteria are a diverse group of microorganisms that enhance the growth of plants under various conditions. In this study, 55 isolates of endogenous rhizobacteria were collected from the rhizosphere of Avicennia marina, Suaeda vermiculata, Salsola soda, Anabasis setifera, Salicornia europaea, Arthrocnemum macrostachyum, Limonium axillare, Tetraena qatarensis, Aeluropus lagopoides, and Prosopis juliflora. The isolates were evaluated in-vitro for their antagonist potential against Fusarium oxysporum and Botrytis cinerea using the dual culture technique, where the maximum growth inhibition reached 49% and 57%, respectively. In-vivo evaluation was accomplished to determine the growth-promoting potential of the rhizobacteria under greenhouse conditions where the strain ANABR3 (Bacillus subtilis) showed the strongest growth-promoting effects. Further in-vivo testing regarding the effectiveness of rhizobacteria in the presence of the phytopathogen was also completed using the Hoagland medium. LEMR3 and SALIR5 (both identified as two strains of B. subtilis) supported the tomato seedlings to overcome the disease and significantly (p ≤ 0.05) increased above and belowground biomass compared to the control. Additionally, several characterizing tests were carried out on the selected strains, these strains were found to possess numerous features that promote plant growth directly and indirectly such as the production of IAA, HCN, hydrolytic enzymes, ACC deaminase, NH3, and some rhizobacteria were capable of phosphate solubilization. In conclusion, this study showed that local rhizobacterial isolates collected from arid lands possess valuable traits, making them promising bio-control agents and bio-fertilizers for agricultural purposes.

Belowground Biomass Changed the Regulatory Factors of Soil N2O Funder N and Water Additions in a Temperate Steppe of Inner Mongolia

Belowground Biomass Changed the Regulatory Factors of Soil N2O Funder N and Water Additions in a Temperate Steppe of Inner Mongolia

Modeling the variability in phenology-based growth dynamics of Spartina alterniflora with latitude

The variation in dynamics of translocation between above- and below-ground biomass of Spartina alterniflora, the dominant blue carbon source in North American saltmarshes, was studied across latitude using Phenology-based Growth dynamic model (PG model). The study shows that the main sources of the carbon translocation to the below-ground tissues varies with latitude. The model analysis suggests both photosynthates and the remobilization of assimilates during growing and senescing periods serve as the main sources of the carbon translocation from above-to below-ground tissues in a higher latitude. However, in the lower latitude regions with a warmer environment, the main source to build up the below-ground biomass was the immediate photosynthesis that occurred during growing seasons. The total photosynthates translocation from above-to below-ground tissues during growing seasons increase as the latitude decreases, whereas the assimilates translocation from the senescing shoots to below-ground during fall seasons increases as latitude increases. Assimilates are allocated from below-to above-ground tissues during the dormancy period in higher latitude. The model enables us to predict both above- and below-ground biomass and quantify the carbon translocation, which helps us understand the main sources of allocation to the below-ground tissues, a critical component of potential blue carbon sequestration, at different phenological events.

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 > 0.001) and biomass accumulation (p > 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

Investigating the impacts of agricultural land use on soil earthworm communities: A case study of northern Zagros Mountains of Iran

Earthworms play a crucial role in the invertebrate community of soil by contributing to the belowground biomass and biogeochemical cycle. Environmental stresses, such as human activities and land use changes, have been found to negatively affect their abundance and diversity. To investigate the impact of agricultural land use and pastures on earthworms' genetic diversity in the Northern Zagros Mountains, we used COI molecular marker and DNA barcoding approaches. We collected earthworm specimens from four farmland sites and six pastures and assessed the abundance and species composition of earthworm communities across the two land uses using quadrat sampling. Using the barcoding method, we identified 13 molecular operational taxonomic units (MOTUs) among the captured earthworms. Our results showed that the number of total MOTUs, density, and earthworm communities differed significantly between the two land uses. We also found that pastures had more abundant earthworms, while farmlands had greater diversity. The diversity of OTUs in the Lumbricidae family was dominant in the agricultural system. Overall, the population of invasive earthworm species in cultivation systems is influenced by chemical inputs and organic materials from plant residues, cover crops, manure, or organic fertilizers. Given the rapid rate of land use change worldwide, especially in Iran, it is crucial to understand the impact of disturbances on earthworms.

Positive effects of leguminous shrub encroachment on multiple ecosystem functions of alpine meadows and steppes greatly depended on increasing soil nutrient

Shrub encroachment in grassland ecosystems is projected to intensify worldwide because of rapid climate change and anthropogenic activity, amplifying the encroachment of woody shrubs and strongly altering the ecosystem function. The effects of leguminous shrub encroachment on multiple dimensions of ecosystem functioning, however, remains poorly understood. This study experimentally quantified the effects of leguminous shrub encroachment (primarily Caragana spinifera Kom.) on various ecosystem functionality relevant to plant diversity, productivity, and storage of soil carbon (C) and nitrogen (N) in alpine meadows and steppes. Further, the study assessed the potential influences of shrub encroachment on ecosystem multifunctionality (EMF, EMF-diversity, EMF-productivity, EMF-C, and EMF-N). Our findings suggest that leguminous shrub encroachment enhanced ecosystem multifunctionality in alpine meadows and steppes. Plant diversity and aboveground biomass of herbaceous species increased after leguminous shrub encroachment. Additionally, the impacts of leguminous shrub encroachment on belowground biomass differed with grassland types, increasing in alpine steppes but decreasing in alpine meadows. The shrub encroachment resulted in significant increases in soil nitrogen and overall nutrient contents in both forms of alpine grasslands. Our findings highlight that shrub encroachment’s increasing of ecosystem multifunctionality was closely related to the promotion of plant diversity, biomass of herbaceous plants, and soil nutrients. Overall, our study demonstrates that the encroachment of leguminous shrubs can promote ecosystem multifunctionality in both alpine meadows and alpine steppes. These findings expand our understanding of the ecosystem functioning in leguminous shrub‐encroached alpine meadows and steppes.

Nitrogen addition alters aboveground C:N:P stoichiometry of plants but not for belowground in an Inner Mongolia grassland

Abstract Nitrogen (N) deposition exhibits significant impacts on ecosystem functions and processes. Previous studies have indicated that N addition has an impact on the stoichiometry of plant leaf C:N:P ratios. However, few studies have focused on effects of N addition on belowground systems. This study aims to examine the impact of 7 years of N addition on above- and belowground C:N:P stoichiometry at plant community level in a temperate grassland located in Inner Mongolia. A 7-year field N addition experiment was conducted, which included six treatments: Cont: control; N1: 0.4 mol·m−2 N; N2: 0.8 mol·m−2 N; N3: 1.6 mol·m−2 N; N4: 2.8 mol·m−2 N; N5: 4 mol·m−2 N with six replicates. Above- and belowground plant biomass and C:N:P stoichiometry were measured and analyzed. Our results showed that N addition resulted in a reduction of aboveground C concentration, but an increase in aboveground N and P concentrations, with a decrease in C:N and C:P ratios and an increase in N:P ratio. Furthermore, the aboveground C, N, and P pools all exhibited an increase as a result of N addition. However, N addition did not have any significant effect on belowground C, N, P concentrations, ratios, pools, or stoichiometric characteristics in the soil layers of 0–10, 10–30, 30–50, and 50–100 cm. These results suggest that increasing levels of N deposition significantly alter the aboveground C:N:P stoichiometry at the plant community level, which may affect functions and processes in the grassland ecosystem, but have little effect on belowground C:N:P stoichiometry.

Assessment of Carbon Sequestration in Private Forests across Two Different Physiographic Regions of Nepal: Implications for Conservation and Climate Change Mitigation

Private forests offer diverse ecosystem services, including carbon sequestration and biodiversity conservation, which are crucial for Nepal. However, there is a notable absence of comprehensive research on these services. Assessing carbon sequestration in private forests can have economic advantages for forest owners by promoting resource conservation and contributing to greenhouse gas reduction. This study aims to estimate and compare carbon stocks in private forests located in two distinct physiographic regions of Nepal while also identifying the factors influencing these carbon stocks. The analysis focuses on 16 private forests (with 0.1 to 0.5 hectares) each from Chitwan district (Terai region) and Kavrepalanchok district (Hilly region). Field data collection involved direct measurements of tree and sapling diameter at breast height (DBH), as well as height and class of trees and poles, utilizing a total enumeration method. These collected values were utilized to calculate aboveground biomass (AGTB), aboveground sapling biomass (AGSB), belowground biomass, and carbon stock. Private forests of Terai region were dominated by Shorea borneensis, Tectona grandis, and Dalbergia sissoo, whereas the Hilly region was dominated by Pinus patula, Alnus nepalensis, Schima wallichii, and Quercus leucotrichophora. The aboveground biomass carbon in the Terai region’s private forests was estimated to be 83.53 t·ha−1, while in the Hilly region, it was 37.32 t·ha−1. The belowground biomass carbon in the Terai region’s private forests was found to be 21.72 t·ha−1, compared to 9.70 t·ha−1 in the Hilly region. Consequently, the estimated total carbon stock in the Terai and Hilly regions’ private forests was 105.25 t·ha−1 (386.26 t·ha−1 CO2-eq) and 47.02 t·ha−1 (172.57 t·ha−1 CO2-eq), respectively. Carbon sequestration in the Terai region’s private forests was discovered to be 2.24 times higher than that in the Hilly region. These findings underscore the significant potential of private forests, which can generate economic benefits through carbon trading and leverage mechanisms such as REDD+/CDM to promote sustainable conservation practices.

Organic carbon stocks of Great British saltmarshes

Coastal wetlands, such as saltmarshes, are globally widespread and highly effective at capturing and storing ‘blue carbon’ and have the potential to regulate climate over varying timescales. Yet only Australia and the United States of America have national inventories of organic carbon held within saltmarsh habitats, hindering the development of policies and management strategies to protect and preserve these organic carbon stores. Here we couple a new observational dataset with 4,797 samples from 26 saltmarshes across Great Britain to spatially model organic carbon stored in the soil and the above and belowground biomass of Great British saltmarshes. Using average values derived from the 26 marshes, we deliver first-order estimates of organic carbon stocks across Great Britain’s 448 saltmarshes (451.66 km2). The saltmarshes of Great Britain contain 5.20 ± 0.65 Mt of organic carbon, 93% of which is in the soil. On average, the saltmarshes store 11.55 ± 1.56 kg C m-2 with values ranging between 2.24 kg C m-2 and 40.51 kg C m-2 depending on interlinked factors such as geomorphology, organic carbon source, sediment type (mud vs sand), sediment supply, and relative sea level history. These findings affirm that saltmarshes represent the largest intertidal blue carbon store in Great Britain, yet remain an unaccounted for component of the United Kingdom’s natural carbon stores.

Effects of grazing on grassland biomass and biodiversity: A global synthesis

ContextLivestock grazing, a common method of grassland utilization, has profound effects on the plant biomass and biodiversity of grassland ecosystems. However, the overall directions and magnitudes of such effects, especially involving multiple livestock types and grazing seasons, remain poorly understood on a global scale. ObjectivesWe conducted a meta-analysis to evaluate the size and direction of the overall effects of grazing on grassland plant biomass and plant diversity; and to estimate the variation of these responses with area types, livestock types, grazing seasons, and grazing intensities. MethodsWe performed a comprehensive search of the Web of Science® and the China National Knowledge Infrastructure (CNKI) (1950–2019) using certain search terms, and considered the studies cited by several recent related syntheses. We compiled data from 175 field manipulative studies at 200 sites by selecting studies that satisfied five criteria. ResultsGrazing significantly decreased aboveground (−38.5%), belowground (−14.7%), and total biomass (−20.6%), but did not significantly change root–shoot ratio, species richness, or evenness. The effects of grazing on plant biomass and diversity depended on climate types and grazing patterns. Specifically, grazing significantly decreased plant total biomass and belowground biomass in dry areas only, but increased rootshoot ratio in wet areas only. Growing season and year-long grazing decreased total biomass, whereas non-growing season grazing had not changed total biomass. Among livestock types (bulk feeder, concentrate selectors, intermediate feeder or mixed), only intermediate feeder grazing significantly decreased belowground biomass (−16.5%) and total biomass (−25.3%). Heavy grazing significantly decreased belowground biomass (−19.2%), total biomass (−24.3%) and plant evenness (−21.2%), but not light and moderate grazing. ConclusionsAboveground biomass was more sensitive to grazing than belowground biomass, and only over grazing decreased grassland biodiversity. Under the same grazing intensities, mixed livestock or bulk feeder grazing in the non-growing season probably is one of the ways to maintain plant diversity and sustainable development of grassland agriculture. ImplicationsOur results highlight the key role of grazing patterns and climate types in mediating plant biomass and biodiversity in response to grazing disturbance, and should be considered in devising the sustainable grazing management of grasslands.

The vitality of native grassland plants in current urban climatic conditions in Gauteng, South Africa

Plants are essential components of urban microclimates, as they can help mitigate some of the adverse effects of urbanisation, enhance environmental quality, and thus contribute to overall species well-being and the sustainability of cities. Urban planners and policymakers often incorporate green infrastructure and urban greening into their strategies to create healthier and more livable urban environments. Plants are primary producers, serving as a baseline for the attraction and habitat of other species; they also provide vital ecosystem services, such as climate amelioration. Landscape designers and horticulturalists can influence plant selection through built environment interventions, increasing urban ecosystem services and benefits. Based on the evidence of native plant preferences by insects and people and their natural adaptation to regional climatic extremes, we tested, through an experimental study, the potential of native grassland plants to survive in assemblages in current urban environments. The study specifically monitored the tolerance of nine native grassland plant species to urban environments over six months in Gauteng, South Africa. A stratified random sampling was done by monitoring permanent quadrats in two purposefully engineered urban native gardens. Plant vitality was evaluated using chlorophyll a fluorescence. General climate data were obtained from a local weather station. Microclimatic temperature and humidity data were collected at each site and quadrat using Hygrochron High-Resolution Temperature and Humidity data loggers. The results indicated that all nine native plant species functioned with good photosynthetic health and can be recommended as resilient species that tolerate current urban conditions. Correlation studies indicated that two forb species, Haplocarpha lyrata and Scabiosa columbaria, showed great tolerance to current urban conditions. This vitality is likely contributed to their winter dormancy morphologically based on below-ground biomass, and their physiological adaptation to tolerate both wet and dry habitat conditions. This points to the potential of grassland forb species for urban use and the potential for climate adaptation in grassland areas.

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.

Allometric determinations in the early development of Schoenoplectus californicus to monitor nutrient uptake in constructed wetlands

Studies of Schoenoplectus californicus focus on the development of aboveground biomass estimations. However, below-ground assessments are important for net primary productivity monitoring in wetlands. This study aims to monitor nutrient assimilation by developing allometric models for above and below-ground biomass estimation of S. californicus in constructed wetlands. The plants we evaluated were grown in vitro, allowing us to control the experimental conditions. The results show that shoot length and apex diameter are significant parameters for building our models. Two non-destructive allometric equations were established to predict above and below-ground biomass and the models were highly significant (R2 = 0.79 and 0.49, p < 0.001). During active growth, both the aboveground and below-ground components showed to be essential for removing nutrients from the water. Both non-destructive equations allowed the monitoring of biomass accumulation in constructed wetlands for seven months, demonstrating that this low-cost method can be used to evaluate the performance of wetlands for wastewater.

Biomass estimation models for Acacia saligna trees in restored landscapes

Acacia saligna, originating from Australia, is a naturalized multipurpose tree species widely grown to restore degraded lands of Africa. The contribution of A. saligna in biomass restoration can be quantified using a precise estimation of tree biomass carbon. This study developed species-specific allometric models and evaluated the spatial variation of tree biomass across restored areas in exclosures and open grazing landscapes. These models could play a considerable role in the monitoring of carbon dynamics across A. saligna planation dominated areas. We harvested, excavated, and weighed twenty-one sample trees representing different size classes to develop allometric models for the estimation of aboveground (AGB), belowground (BGB) and total tree (TB) biomass. The average dry-to-fresh mass ratio and the root-to-shoot ratio was 0.47 (±0.13) and 0.28 (±0.14), respectively. Tree biomass significantly correlated with diameter at breast height (r = 0.93; P < 0.001), diameter at stump height (r = 0.88, P < 0.001) and tree height (r = 0.56, P < 0.05). Our best biomass estimation models explained 86%, 82% and 87% of variations in AGB, BGB, and TB, respectively. Models using DSH and DSH & H explained 70%–78% of the variation in AGB, BGB, and TB. Estimated C-stock showed a significant relationship with stem density (R 2 = 0.91, P < 0.01). Estimated TB varied between 1.5–18 Mg ha−1 on grazed land and exclosures. Estimated C-stocks in the exclosure exceeded the estimated C-stock in the open grazing land by ∼60%. This implies that with proper management practices and enrichment planting A. saligna significantly contributes to increasing carbon accumulation on degraded landscapes, playing a key role in climate change mitigation efforts while improving land productivity.

Geographic variability in headward erosion of marsh tidal creeks: Ecological and physical causes

AbstractExpansion of drainage networks through the headward erosion of tidal creeks is an eco‐geomorphologic response of salt marshes to accelerated sea‐level rise (SLR). This response can counter the negative impacts of an elevation deficit by increasing drainage and encouraging plant health, thereby reducing potential for submergence and marsh platform loss. In the wetlands of Cape Romain, SC, intense bioturbation near creek heads by the common marsh crab Sesarma reticulatum has been found to facilitate sediment erosion and rapid creek growth. This keystone grazer has been recently observed to have increasing influence on landscape evolution throughout the southeast US coast. Here, we compare measurements taken at Sapelo Island, GA, with those previously collected at Cape Romain, to confirm that eco‐geomorphic feedbacks facilitating creek growth at each location are similar, and to compare these processes under differing background conditions. We use sediment cores, precise elevation measurements and historical imagery to compare substrate properties, elevation within the tidal frame, creek growth rates and drainage morphology at both sites. Our results show identical processes; however, the higher elevation of the marsh at Sapelo Island leads to shallower and shorter periods of tidal inundation, explaining the greater soil strength and lower belowground biomass compared with the marsh at Cape Romain. The smaller tidal range at the site in Cape Romain compared with Sapelo Island translates to a proportionally shallower depth of tidal creeks, which therefore requires less erosion to produce headward creek extension. These effects are likely to have contributed to slower growth rates of tidal creeks at Sapelo Island during the past several decades of SLR. Our findings highlight the similarities in process but differences in rates in how marshes are responding to climate‐related stress.

Tree-based carbon sequestration and storage abilities vary in natural and plantation forest ecosystems

Little is known about the relevance of natural forests and plantations in the wake of global warming and climate change. Understanding the impacts of land use conversion from natural forests to plantations on carbon sequestration and storage is critical for sustainable land and forest management. In this study, tree-based carbon sequestration and storage abilities were assessed in natural and plantation forest ecosystems. Four plots within a natural forest and cashew orchard were randomly chosen and four belt transects were established. In each plot, tree species were identified and their density, height, Diameter at Breast Height (DBH) enumerated and measured, respectively. In each plot, litter boxes were placed to collect litter weekly. Soils (at 0 -15 cm and 15 – 30 cm) within each plot were obtained with soil auger. AGB (aboveground biomass), BGB (belowground biomass), AGC (aboveground carbon) and BGC (belowground carbon) were calculated using allometric equations for pan moist and dry tropical forest. Twenty-three and eleven tree species were found in the forest and orchard, respectively. The forest had the largest total biomass allocation (188.61 Mg ha-1) and carbon stock (146.89 Mg C.ha-1) while the orchard had the least total biomass apportionment (37.20 Mg ha-1) and carbon stock (45.60 Mg ha-1). The forest ecosystem had the largest sequestration ability (593.04 Mg CO2ha-1) which followed this trend: aboveground (295.18 Mg CO2ha-1) &gt; belowground (60.51 Mg CO2ha-1) &gt; soils (133.73 Mg CO2ha-1) &gt; litter (49.62 Mg CO2ha-1) while cashew orchard had the least sequestration ability (167.37 Mg CO2ha-1) which followed this order: soil (99.09 Mg CO2ha-1) &gt; litter (35.75 Mg CO2ha-1) &gt; aboveground (27.00 Mg CO2ha-1) &gt; belowground (5.53 Mg CO2ha-1). From these results, land use change affects carbon budgets of ecosystems, hence, this study argues for protection of natural forest while practicing afforestation towards global warming mitigation.

Plant diversity and grasses increase root biomass in a rainfall and grassland diversity manipulation

The loss of plant productivity with declining diversity is well established, exceeding other global change drivers including drought. These patterns are most clearly established for aboveground productivity, it remains poorly understood whether productivity increases associated with diversity are replicated belowground. To address this gap, we established a plant diversity-manipulation experiment in 2018. It is a full factorial manipulation of plant species richness and community composition, and precipitation. Three and five years post-establishment, two bulk soil cores (20cm depth) were collected and composited from each plot and were processed for roots to determine belowground biomass as root standing crop. We observed a strong positive relationship between richness and aboveground production and belowground biomass, generating positive combined above and belowground with diversity. Root standing crop increased 1.4-fold from years three to five. Grass communities produced more root biomass (monoculture mean 463.9 ± 410.3g m−2), and the magnitude of the relationship between richness and root standing crop was greatest within those communities. Legume communities produced the fewest roots (monoculture mean 212.2 ± 155.1g m−2), and belowground standing crop was not affected by diversity. Root standing crops in year three were 1.8 times higher under low precipitation conditions, while in year five we observed comparable root standing crops between precipitation treatments. Plant family was a strong mediator of increased belowground biomass observed with diversity, with single family grass and aster families generating 1.7 times greater root standing crops in six compared to single species communities, relationships between diversity and aboveground production were consistently observed in both single-family and multiple family communities. Diverse communities with species from multiple families generated only 1.3 times the root standing crop compared to monoculture average root biomass. We surprisingly observe diverse single family communities can generate increases in root standing crops that exceed those generated by diverse multiple family communities, highlighting the importance of plant richness within plant family for a given community. These patterns have potential implications for understanding the interactions of multiple global change drivers as changes in both precipitation and plant community composition do alter whether plant production aboveground is translated belowground biomass.

Effects of elevated carbon dioxide on plant growth and leaf photosynthesis of annual ryegrass along a phosphorus deficiency gradient

IntroductionSoil phosphorus (P) deficiency limits plant growth and productivity in grassland ecosystems and may moderate the growth-promoting effects of “carbon dioxide (CO2) fertilization effect”.MethodsTo evaluate the interactive effects of these two factors on the growth and physiology for annual ryegrass (Lolium multiflorum Lam.), plants were grown in controlled growth chambers with a range of P supply (0.004, 0.012, 0.02, 0.06, 0.1 and 0.5 mM) under two levels of CO2 (400 and 800 μmol mol-1, respectively).ResultsElevated [CO2] dramatically increased the aboveground biomass and net photosynthetic rates of annual ryegrass by 14.5% and 25.3% under sufficient P supply (0.5 mM), respectively, whereas decreased the belowground biomass and net photosynthetic rates under lower P supply of P0.004, P0.02, and P0.06. Two-way ANOVA results showed that CO2 × P (p &amp;lt; 0.001) significantly affected stomatal traits, leaf photosynthesis and biomass. The stimulation of growth and photosynthesis by elevated CO2 concentration (e[CO2]) was reduced or highly suppressed, indicating that the sensitivity of annual ryegrass to P deficiency was enhanced under e[CO2].DiscussionThese results indicated that P limitation may offset the positive effects of e[CO2] on plant growth by altering stomatal traits, leaf photochemical processes and biochemical composition in annual ryegrass.

An inferior competitor is a successful invader due to its stress tolerance and productivity

The invasion of ecosystems by non-native species is recognized as one of the most significant global challenges, particularly in semiarid regions where native biodiversity is already under stress from drought and land degradation. The implicit assumption is that invaders are strong competitors, but a greenhouse pairwise experiment conducted to examine intraspecific and interspecific competition effects of Opuntia ficus-indica, a widespread invader in semiarid ecosystems, with two species native to the highlands of Eritrea, Ricinus communis and Solanum marginatum, revealed that O. ficus-indica is a weak competitor. The unique ability of O. ficus-indica’s fallen cladodes to undergo vegetative growth becomes a fundamental trait contributing to its spread. This growth strategy allows O. ficus-indica to outgrow native species and establish a significant presence. In direct interaction, the competition in aboveground productivity measured by the logarithmic response ratio for O. ficus-indica was 3.4-fold and 5.9-fold higher than for R. communis and S. marginatum, respectively. Belowground, the native R. communis was facilitated (− 1.00 ± 0.69) by O. ficus-indica which itself suffered from high competition. This pattern became even more evident under water shortage, where aboveground competition for S. marginatum decreased 5.7-fold, and for O. ficus-indica, it increased 1.4-fold. Despite being a poor competitor, O. ficus-indica outperformed R. communis and S. marginatum in both aboveground (4.3 and 3.8 times more) and belowground (27 and 2.8 times more) biomass production, respectively. The findings of this study challenge the common interpretation that invasive species are strong competitors and highlight the importance of considering other factors, such as productivity and tolerance limits when assessing the potential impacts of invasive species on semiarid ecosystems.

Climate Factors Affect Above–Belowground Biomass Allocation in Broad-Leaved and Coniferous Forests by Regulating Soil Nutrients

The allocation of plant biomass above and below ground reflects their strategic resource utilization, crucial for understanding terrestrial carbon flux dynamics. In our comprehensive study, we analyzed biomass distribution patterns in 580 broadleaved and 345 coniferous forests across China from 2005 to 2020, aiming to discern spatial patterns and key drivers of belowground biomass proportion (BGBP) in these ecosystems. Our research revealed a consistent trend: BGBP decreases from northwest to southeast in both forest types. Importantly, coniferous forests exhibited significantly higher BGBP compared to broadleaved forests (p &lt; 0.001). While precipitation and soil nutrients primarily influenced biomass allocation in broadleaved forests, temperature and soil composition played a pivotal role in coniferous forests. Surprisingly, leaf traits had a negligible impact on BGBP (p &gt; 0.05). Climatic factors, such as temperature and rainfall, influenced biomass partitioning in both strata by altering soil nutrients, particularly soil pH. These findings provide valuable insights into understanding carbon sequestration dynamics in forest ecosystems and improving predictions of the future trajectory of this critical carbon cycle component.