17 research outputs found
Legume Shrubs Are More Nitrogen-Homeostatic than Non-legume Shrubs
Legumes are characterized as keeping stable nutrient supply under nutrient-limited conditions. However, few studies examined the legumes' stoichiometric advantages over other plants across various taxa in natural ecosystems. We explored differences in nitrogen (N) and phosphorus (P) stoichiometry of different tissue types (leaf, stem, and root) between N2-fixing legume shrubs and non-N2-fixing shrubs from 299 broadleaved deciduous shrubland sites in northern China. After excluding effects of taxonomy and environmental variables, these two functional groups differed considerably in nutrient regulation. N concentrations and N:P ratios were higher in legume shrubs than in non-N2-fixing shrubs. N concentrations were positively correlated between the plants and soil for non-N2-fixing shrubs, but not for legume shrubs, indicating a stronger stoichiometric homeostasis in legume shrubs than in non-N2-fixing shrubs. N concentrations were positively correlated among three tissue types for non-N2-fixing shrubs, but not between leaves and non-leaf tissues for legume shrubs, demonstrating that N concentrations were more dependent among tissues for non-N2-fixing shrubs than for legume shrubs. N and P concentrations were correlated within all tissues for both functional groups, but the regression slopes were flatter for legume shrubs than non-N2-fixing shrubs, implying that legume shrubs were more P limited than non-N2-fixing shrubs. These results address significant differences in stoichiometry between legume shrubs and non-N2-fixing shrubs, and indicate the influence of symbiotic nitrogen fixation (SNF) on plant stoichiometry. Overall, N2-fixing legume shrubs are higher and more stoichiometrically homeostatic in N concentrations. However, due to excess uptake of N, legumes may suffer from potential P limitation. With their N advantage, legume shrubs could be good nurse plants in restoration sites with degraded soil, but their P supply should be taken care of during management according to our results
The links between ecosystem multifunctionality and above- and belowground biodiversity are mediated by climate
Plant biodiversity is often correlated with ecosystem functioning in terrestrial ecosystems. However, we know little about the relative and combined effects of above-and belowground biodiversity on multiple ecosystem functions (for example, ecosystem multifunctionality, EMF) or how climate might mediate those relationships. Here we tease apart the effects of biotic and abiotic factors, both above- and belowground, on EMF on the Tibetan Plateau, China. We found that a suite of biotic and abiotic variables account for up to 86% of the variation in EMF, with the combined effects of above-and belowground biodiversity accounting for 45% of the variation in EMF. Our results have two important implications: first, including belowground biodiversity in models can improve the ability to explain and predict EMF. Second, regional-scale variation in climate, and perhaps climate change, can determine, or at least modify, the effects of biodiversity on EMF in natural ecosystems.National Basic Research Program of China [2014CB954004, 2014CB954002]; Strategic Priority Research Program of the Chinese Academy of Sciences [XDA05050404, XDB03030403]; National Natural Science Foundation of China [31025005, 31321061, 41071167]; National Science Foundation Dimensions of Biodiversity grant [NSF-1136703]; Danish National Research Foundation; US Department of Energy, Office of Science, Office of Biological and Environmental Research, Terrestrial Ecosystem Sciences Program Award [DE-SC0010562]SCI(E)[email protected]
Increasing water availability and facilitation weaken biodiversity-biomass relationships in shrublands
Positive biodiversityâecosystemâfunctioning (BEF) relationships are commonly found in experimental and observational studies, but how they vary in different environmental contexts and under the influence of coexisting life forms is still controversial. Investigating these variations is important for making predictions regarding the dynamics of plant communities and carbon pools under global change. We conducted this study across 433 shrubland sites in northern China. We fitted structural equation models (SEMs) to analyze the variation in the speciesârichnessâbiomass relationships of shrubs and herbs along a wetness gradient and general liner models (GLMs) to analyze how shrub or herb biomass affected the speciesârichnessâbiomass relationship of the other life form. We found that the positive speciesârichnessâbiomass relationships for both shrubs and herbs became weaker or even negative with higher water availability, likely indicating stronger interspecific competition within life forms under more benign conditions. After accounting for variation in environmental contexts using residual regression, we found that the benign effect of greater facilitation by a larger shrub biomass reduced the positive speciesârichnessâbiomass relationships of herbs, causing them to become nonsignificant. Different levels of herb biomass, however, did not change the speciesârichnessâbiomass relationship of shrubs, possibly because greater herb biomass did not alter the stress level for shrubs. We conclude that biodiversity in the studied plant communities is particularly important for plant biomass production under arid conditions and that it might be possible to use shrubs as nurse plants to facilitate understory herb establishment in ecological restoration
Legume Shrubs Are More Nitrogen-Homeostatic than Non-legume Shrubs
Legumes are characterized as keeping stable nutrient supply under nutrient-limited conditions. However, few studies examined the legumes' stoichiometric advantages over other plants across various taxa in natural ecosystems. We explored differences in nitrogen (N) and phosphorus (P) stoichiometry of different tissue types (leaf, stern, and root) between N-2-fixing legume shrubs and non-N-2-fixing shrubs from 299 broadleaved deciduous shrubland sites in northern China. After excluding effects of taxonomy and environmental variables, these two functional groups differed considerably in nutrient regulation. N concentrations and N:P ratios were higher in legume shrubs than in non N-2-fixing shrubs. N concentrations were positively correlated between the plants and soil for non-N-2-fixing shrubs, but not for legume shrubs, indicating a stronger stoichiometric homeostasis in legume shrubs than in non-N-2-fixing shrubs. N concentrations were positively correlated among three tissue types for non-N-2-fixing shrubs, but not between leaves and non-leaf tissues for legume shrubs, demonstrating that N concentrations were more dependent among tissues for non-N-2-fixing shrubs than for legume shrubs. N and P concentrations were correlated within all tissues for both functional groups, but the regression slopes were flatter for legume shrubs than non-N-2-fixing shrubs, implying that legume shrubs were more P limited than non-N-2-fixing shrubs. These results address significant differences in stoichiometry between legume shrubs and non N-fixing shrubs, and indicate the influence of symbiotic nitrogen fixation (SNP) on plant stoichiometry. Overall,N-2-fixing legume shrubs are higher and more stoichiometrically homeostatic in N concentrations. However, due to excess uptake of N, legumes may suffer from potential P limitation. With their N advantage, legume shrubs could be good nurse plants in restoration sites with degraded soil, but their P supply should be taken care of during management according to our results.Ministry of Science and Technology of China [2014CB954001]; National Natural Science Foundation of China [31170486, 31621091]; Chinese Academy of Sciences [XDA05050301]SCI(E)ARTICLE
Investigation and Improvement of Stall Characteristic of High-Lift Configuration without Slats
Generation of a DMD loss-of-function mutant human embryonic stem cell lines by CRISPR base editing
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disorder, which is caused mostly by frame-disrupting, out-of-frame variation in the dystrophin (DMD) gene. Loss-of- function mutations are the most common type of mutation in DMD, accounting for approximately 60â90% of all DMD variations. In this study, we used adenine base editing to generate a human embryonic stem cell line with splice-site mutations to mimic exon deletion variants in clinical Duchenne muscular dystrophy patients. This cell line has differentiation potential and a normal karyotypic
Determinants of postâfire regeneration demography in a subtropical monsoonâclimate forest in Southwest China
Understanding the determinants of postâfire regeneration is critical for determining an appropriate restoration program following fire disturbances. However, studies addressing the drivers of postâfire regeneration of forests in monsoon climate are rare. This study explored the temporal and spatial variations of postâfire forest regeneration in the Central Yunnan Plateau of Southwest China, and disentangled the direct and indirect effects of the environmental factors via structural equation models (SEMs). We found that the overall postâfire regeneration density was generally greater for the habitat with higher values of elevation, preâfire abundance, and soil pH. Postâfire regeneration was mainly composed of resprouts; seedlings were less relevant and appeared later. The SEM approach showed more variation of recruitment in resprouting (R = 0.66) than seeding (R = 0.33), and revealed different direct and indirect pathways. Resprouts were widely distributed, and significantly influenced by preâfire abundance, elevation, soil pH, and years since the last fire. In contrast, seedlings preferentially occurred in infertile habitats, and were mainly influenced by topographic position and soil nutrients, showing distinct distribution from that of resprouts. Overall, forests under the subtropical monsoon climate in the Central Yunnan Plateau were resilient to fire mainly due to rapid postâfire resprouting. These findings indicate the complementary roles of resprouting and seeding in post- fire regeneration, and help to understand the mechanisms that regulate post-fire plant regeneration in a spatially heterogeneous landscape. Our results should contribute to improving the postâfire management of forest ecosystems under the influence of a semiâhumid monsoon climate.This study was supported by the Projects of the National Natural Science Foundation of China (No. 41971228), and the Key Research Development Plan of the Ministry of Science and Technology of China (2017YFC0505200
Increasing water availability and facilitation weaken biodiversityâbiomass relationships in shrublands
Positive biodiversityâecosystemâfunctioning (BEF) relationships are commonly found in experimental and observational studies, but how they vary in different environmental contexts and under the influence of coexisting life forms is still controversial. Investigating these variations is important for making predictions regarding the dynamics of plant communities and carbon pools under global change. We conducted this study across 433 shrubland sites in northern China. We fitted structural equation models (SEMs) to analyze the variation in the speciesârichnessâbiomass relationships of shrubs and herbs along a wetness gradient and general liner models (GLMs) to analyze how shrub or herb biomass affected the speciesârichnessâbiomass relationship of the other life form. We found that the positive speciesârichnessâbiomass relationships for both shrubs and herbs became weaker or even negative with higher water availability, likely indicating stronger interspecific competition within life forms under more benign conditions. After accounting for variation in environmental contexts using residual regression, we found that the benign effect of greater facilitation by a larger shrub biomass reduced the positive speciesârichnessâbiomass relationships of herbs, causing them to become nonsignificant. Different levels of herb biomass, however, did not change the speciesârichnessâbiomass relationship of shrubs, possibly because greater herb biomass did not alter the stress level for shrubs. We conclude that biodiversity in the studied plant communities is particularly important for plant biomass production under arid conditions and that it might be possible to use shrubs as nurse plants to facilitate understory herb establishment in ecological restoration.ISSN:0012-9658ISSN:1939-917
Increasing water availability and facilitation weaken biodiversityâbiomass relationships in shrublands
Positive biodiversityâecosystemâfunctioning (BEF) relationships are commonly found in experimental and observational studies, but how they vary in different environmental contexts and under the influence of coexisting life forms is still controversial. Investigating these variations is important for making predictions regarding the dynamics of plant communities and carbon pools under global change. We conducted this study across 433 shrubland sites in northern China. We fitted structural equation models (SEMs) to analyze the variation in the speciesârichnessâbiomass relationships of shrubs and herbs along a wetness gradient and general liner models (GLMs) to analyze how shrub or herb biomass affected the speciesârichnessâbiomass relationship of the other life form. We found that the positive speciesârichnessâbiomass relationships for both shrubs and herbs became weaker or even negative with higher water availability, likely indicating stronger interspecific competition within life forms under more benign conditions. After accounting for variation in environmental contexts using residual regression, we found that the benign effect of greater facilitation by a larger shrub biomass reduced the positive speciesârichnessâbiomass relationships of herbs, causing them to become nonsignificant. Different levels of herb biomass, however, did not change the speciesârichnessâbiomass relationship of shrubs, possibly because greater herb biomass did not alter the stress level for shrubs. We conclude that biodiversity in the studied plant communities is particularly important for plant biomass production under arid conditions and that it might be possible to use shrubs as nurse plants to facilitate understory herb establishment in ecological restoration.ISSN:0012-9658ISSN:1939-917