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1.
Artigo em Inglês | MEDLINE | ID: mdl-32393624

RESUMO

Late-spring frosts (LSFs) affect the performance of plants and animals across the world's temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resistance strategies of Northern Hemisphere woody species to infer trees' adaptations for minimizing frost damage to their leaves and to forecast forest vulnerability under the ongoing changes in frost frequencies. Trait values on leaf-out and leaf-freezing resistance come from up to 1,500 temperate and boreal woody species cultivated in common gardens. We find that areas in which LSFs are common, such as eastern North America, harbor tree species with cautious (late-leafing) leaf-out strategies. Areas in which LSFs used to be unlikely, such as broad-leaved forests and shrublands in Europe and Asia, instead harbor opportunistic tree species (quickly reacting to warming air temperatures). LSFs in the latter regions are currently increasing, and given species' innate resistance strategies, we estimate that ∼35% of the European and ∼26% of the Asian temperate forest area, but only ∼10% of the North American, will experience increasing late-frost damage in the future. Our findings reveal region-specific changes in the spring-frost risk that can inform decision-making in land management, forestry, agriculture, and insurance policy.

2.
Glob Chang Biol ; 26(6): 3429-3442, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32215999

RESUMO

CO2 fluxes from wood decomposition represent an important source of carbon from forest ecosystems to the atmosphere, which are determined by both wood traits and climate influencing the metabolic rates of decomposers. Previous studies have quantified the effects of moisture and temperature on wood decomposition, but these effects were not separated from the potential influence of wood traits. Indeed, it is not well understood how traits and climate interact to influence wood CO2 fluxes. Here, we examined the responses of CO2 fluxes from dead wood with different traits (angiosperm and gymnosperm) to 0%, 35%, and 70% rainfall reduction across seasonal temperature gradients. Our results showed that drought significantly decreased wood CO2 fluxes, but its effects varied with both taxonomical group and drought intensity. Drought-induced reduction in wood CO2 fluxes was larger in angiosperms than gymnosperms for the 35% rainfall reduction treatment, but there was no significant difference between these groups for the 70% reduction treatment. This is because wood nitrogen density and carbon quality were significantly higher in angiosperms than gymnosperms, yielding a higher moisture sensitivity of wood decomposition. These findings were demonstrated by a significant positive interaction effect between wood nitrogen and moisture on CO2 fluxes in a structural equation model. Additionally, we ascertained that a constant temperature sensitivity of CO2 fluxes was independent of wood traits and consistent with previous estimates for extracellular enzyme kinetics. Our results highlight the key role of wood traits in regulating drought responses of wood carbon fluxes. Given that both climate and forest management might extensively modify taxonomic compositions in the future, it is critical for carbon cycle models to account for such interactions between wood traits and climate in driving dynamics of wood decomposition.

3.
Sci Total Environ ; 701: 135044, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726403

RESUMO

Insects play an important role in the spread of viruses from infected plants to healthy hosts through a variety of transmission strategies. Environmental factors continuously influence virus transmission and result in the establishment of infection or disease. Plant virus diseases become epidemic when viruses successfully dominate the surrounding ecosystem. Plant-insect vector-virus interactions influence each other; pushing each other for their benefit and survival. These interactions are modulated through environmental factors, though environmental influences are not readily predictable. This review focuses on exploiting the diverse relationships, embedded in the plant-insect vector-virus triangle by highlighting recent research findings. We examined the interactions between viruses, insect vectors, and host plants, and explored how these interactions affect their behavior.


Assuntos
Mudança Climática , Insetos Vetores , Vírus de Insetos , Vírus de Plantas , Animais , Ecossistema , Interações Hospedeiro-Patógeno , Insetos , Doenças das Plantas , Plantas
4.
Ecol Lett ; 23(1): 79-87, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31631491

RESUMO

Increases in niche complementarity have been hypothesised to reduce the intensity of interspecific competition within natural forests. In regions currently experiencing potentially enhanced growth under global environmental change, niche complementarity may become even more beneficial. However, few studies have provided direct evidence of this mechanism. Here, we use data from 180 permanent sample plots in Manitoba, Canada, with a full spatial mapping of all stems, to show that complementarity effects on average increased with neighbourhood competition intensity and temporally rising CO2 , warming and water availability. Importantly, complementarity effects increased with both shade tolerance and phylogenetic dissimilarity between the focal tree and its neighbours. Our results provide further evidence that increasing stand functional and phylogenetic diversity can improve individual tree productivity, especially for individuals experiencing intense competition and may offer an avenue to maintain productivity under global environmental change.


Assuntos
Biodiversidade , Taiga , Canadá , Florestas , Filogenia
5.
Sci Total Environ ; 705: 135992, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31841928

RESUMO

Soil enzymes play critical roles in the decomposition of organic matter and determine the availability of soil nutrients, however, there are significant uncertainties in regard to how enzymatic responses to global warming. To reveal the general response patterns and controlling factors of various extracellular enzyme activities (EEA), we collected data from 78 peer-reviewed papers to investigate the responses of extracellular enzyme activities (EEA), including ß-1,4-glucosidase (BG), ß-d-cellobiosidase (CBH), ß-1,4-xylosidase (XYL), leucine amino peptidase (LAP), N-acetyl-glucosaminidase (NAG), urease (URE), phosphatase (PHO), peroxidase (PER), phenol oxidase (POX), and polyphenol oxidase (PPO), to experimental warming. Our results showed that warming treatments increased soil temperature by 1.9 °C on average. The oxidative EEA, calculated as the sum of PER, POX and PPO, was on average stimulated by 9.4% under warming. However, the responses of C acquisition EEA (the sum of BG, CBH and XYL), N acquisition EEA (the sum of LAP, NAG and URE), and P acquisition EEA to warming had large variations across studies. The warming effects on C, N, P acquisition EEA and oxidative EEA tended to increase with soil warming magnitude and duration as well as the mean annual temperature. The response of C acquisition EEA to warming was positively correlated with fungal biomass, while that of P acquisition EEA had positive relationships with fungi: bacteria ratios. The response of oxidative EEA was negatively correlated with the abundance of gram-positive bacterial biomass. Our results suggested that warming consistently stimulated oxidative EEA, but had diverse effects on hydrolytic EEA, which were dependent on the warming magnitude or duration, or environmental factors. The observed relationships between changes in microbial traits and extracellular enzymes suggested that microbial compositions drive changes in enzyme decomposition under warming. Thus, incorporation of microbial modification in biogeochemistry models is essential to better predict ecosystem carbon and nutrient dynamics.


Assuntos
Ecossistema , Solo , Biomassa , Carbono , Aquecimento Global , Microbiologia do Solo
6.
Glob Chang Biol ; 2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31873968

RESUMO

Carbon (C) and nitrogen (N) are the primary elements involved in the growth and development of plants. The C:N ratio is an indicator of nitrogen use efficiency (NUE) and an input parameter for some ecological and ecosystem models. However, knowledge remains limited about the convergent or divergent variation in the C:N ratios among different plant organs (e.g., leaf, branch, trunk, and root) and how evolution and environment affect the coefficient shifts. Using systematic measurements of the leaf-branch-trunk-root of 2,139 species from tropical to cold-temperate forests, we comprehensively evaluated variation in C:N ratio in different organs in different taxa and forest types. The ratios showed convergence in the direction of change but divergence in the rate of change. Plants evolved toward lower C:N ratios in the leaf and branch, with N playing a more important role than C. The C:N ratio of plant organs (except for the leaf) was constrained by phylogeny, but not strongly. Both the change of C:N during evolution and its spatial variation (lower C:N ratio at midlatitudes) help develop the adaptive growth hypothesis. That is, plants with a higher C:N ratio promote NUE under strong N-limited conditions to ensure survival priority, whereas plants with a lower C:N ratio under less N-limited environments benefit growth priority. In nature, larger proportion of species with a high C:N ratio enabled communities to inhabit more N-limited conditions. Our results provide new insights on the evolution and drivers of C:N ratio among different plant organs, as well as provide a quantitative basis to optimize land surface process models.

7.
Artigo em Inglês | MEDLINE | ID: mdl-31625247

RESUMO

Soil organic carbon (SOC) is a valuable resource for mediating global climate change and securing food production. Despite an alarming rate of global plant diversity loss, uncertainties concerning the effects of plant diversity on SOC remain, because plant diversity not only stimulates litter inputs via increased productivity, thus enhancing SOC, but also stimulates microbial respiration, thus reducing SOC. By analysing 1001 paired observations of plant mixtures and corresponding monocultures from 121 publications, we show that both SOC content and stock are on average 5 and 8% higher in species mixtures than in monocultures. These positive mixture effects increase over time and are more pronounced in deeper soils. Microbial biomass carbon, an indicator of SOC release and formation, also increases, but the proportion of microbial biomass carbon in SOC is lower in mixtures. Moreover, these species-mixture effects are consistent across forest, grassland, and cropland systems and are independent of background climates. Our results indicate that converting 50% of global forests from mixtures to monocultures would release an average of 2.70 Pg C from soil annually over a period of 20 years: about 30% of global annual fossil-fuel emissions. Our study highlights the importance of plant diversity preservation for the maintenance of soil carbon sequestration in discussions of global climate change policy.

8.
Sci Adv ; 5(8): eaav1131, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31457076

RESUMO

It has been well established by field experiments that warming stimulates either net ecosystem carbon uptake or release, leading to negative or positive carbon cycle-climate change feedback, respectively. This variation in carbon-climate feedback has been partially attributed to water availability. However, it remains unclear under what conditions water availability enhances or weakens carbon-climate feedback or even changes its direction. Combining a field experiment with a global synthesis, we show that warming stimulates net carbon uptake (negative feedback) under wet conditions, but depresses it (positive feedback) under very dry conditions. This switch in carbon-climate feedback direction arises mainly from scaling effects of warming-induced decreases in soil water content on net ecosystem productivity. This water scaling of warming effects offers generalizable mechanisms not only to help explain varying magnitudes and directions of observed carbon-climate feedback but also to improve model prediction of ecosystem carbon dynamics in response to climate change.

9.
Sci Rep ; 9(1): 8372, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31182823

RESUMO

Saturated hydraulic conductivity (Ks) is one of the most important soil properties that determines water flow behavior in terrestrial ecosystems. However, the Ks of forest soils is difficult to predict due to multiple interactions, such as anthropological and geomorphic processes. In this study, we examined the impacts of vegetation type on Ks and associated mechanisms. We found that Ks differed with vegetation type and soil depth, and the impact of vegetation type on Ks was dependent on soil depth. Ks did not differ among vegetation types at soil depths of 0-10 and 20-30 cm, but was significantly lower in managed forest types (mixed evergreen broad-leaved and coniferous forests, bamboo forests, and tea gardens) than native evergreen broadleaf forests at a depth of 10-20 cm. Boosted regression tree analysis indicated that total porosity, non-capillary porosity, and macro water-stable aggregates were the primary factors that influenced Ks. Our results suggested that vegetation type was a key factor that influences hydraulic properties in subtropical forest soils through the alteration of soil properties, such as porosity and macro water-stable aggregates.

10.
Plant Signal Behav ; 14(6): 1596719, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30957658

RESUMO

Phytohormones are critical in various aspects of plant biology such as growth regulations and defense strategies against pathogens. Plant-virus interactions retard plant growth through rapid alterations in phytohormones and their signaling pathways. Recent research findings show evidence of how viruses impact upon modulation of various phytohormones affecting plant growth regulations. The opinion is getting stronger that virus-mediated phytohormone disruption and alteration weaken plant defense strategies through enhanced replication and systemic spread of viral particles. These hormones regulate plant-virus interactions in various ways that may involve antagonism and cross talk to modulate small RNA (sRNA) systems. The article aims to highlight the recent research findings elaborating the impact of viruses upon manipulation of phytohormones and virus biology.

11.
Ecol Lett ; 22(6): 999-1008, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30920143

RESUMO

Climate and other global environmental changes are major threats to ecosystem functioning and biodiversity. However, the importance of plant diversity in mitigating the responses of functioning of natural ecosystems to long-term environmental change remains unclear. Using inventory data of boreal forests of western Canada from 1958 to 2011, we found that aboveground biomass growth increased over time in species-rich forests but decreased in species-poor forests, and importantly, aboveground biomass loss from tree mortality was smaller in species-rich than species-poor forests. A further analysis indicated that growth of species-rich (but not species-poor) forests was statistically positively associated with rising CO2 , and that mortality in species-poor forests increased more as climate moisture availability decreased than it did in species-rich forests. In contrast, growth decreased and mortality increased as the climate warmed regardless of species diversity. Our results suggest that promoting high tree diversity may help reduce the climate and environmental change vulnerability of boreal forests.


Assuntos
Mudança Climática , Florestas , Taiga , Canadá , Árvores
12.
Sci Total Environ ; 654: 1023-1032, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30841376

RESUMO

Revealing the dynamics of soil aggregate-associated microbial (particularly bacterial) metabolic activity and community structure is of great importance to maintain the soil health and microbial community stability in tea plantation ecosystems. In this study, the bacterial metabolic activity (as measured by Biolog Eco MicroPlates) and community structure (as measured by high-throughput sequencing) were analyzed in soil aggregates, which were collected at the 0-20 cm depth in four tea plantations with different ages (16, 23, 31, and 53 yrs.) in the areas of Western Sichuan, China. A dry-sieving procedure was adopted to separate soil aggregates into four fractions, including >2, 2-1, 1-0.25, and <0.25 mm. In all the tea plantations, the highest levels of soil bacterial metabolic activity (as indicated by average well color development, AWCD) and community diversity (as indicated by Chao 1 and Shannon indices) appeared in the >2 mm fractions, which indicated that these aggregate fractions with complex bacterial communities not only provided biological buffering, but also prevented the dominance of individual microorganisms through predation or competition. Soil aggregates with >2 mm were concentrated in the 23 yrs. tea plantation, implying that this tea plantation possessed the relatively suitable soil environments to the growth and proliferation of soil bacteria, thus increasing their metabolic activity and community diversity. After 23 yrs. of tea planting, the reduction of the >2 mm fractions in the whole-soil accounted for the degradation of soil bacterial communities to some extent. In the meanwhile, soil microbial quotient (the ratio of soil microbial biomass C to organic C) and pH were also important drivers of the variations in soil bacterial communities during tea planting. This study underscored the requirement for sustainable soil managements which could maintain the soil health and bacterial community stability after 23 yrs. of tea planting in the areas of Western Sichuan, China.


Assuntos
Camellia sinensis/crescimento & desenvolvimento , Microbiologia do Solo , Bactérias , Biomassa , Camellia sinensis/microbiologia , Monitoramento Ambiental , Microbiota , Solo/química , Chá
13.
Nat Commun ; 10(1): 1332, 2019 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-30902971

RESUMO

Soil microorganisms are key to biological diversity and many ecosystem processes in terrestrial ecosystems. Despite the current alarming loss of plant diversity, it is unclear how plant species diversity affects soil microorganisms. By conducting a global meta-analysis with paired observations of plant mixtures and monocultures from 106 studies, we show that microbial biomass, bacterial biomass, fungal biomass, fungi:bacteria ratio, and microbial respiration increase, while Gram-positive to Gram-negative bacteria ratio decrease in response to plant mixtures. The increases in microbial biomass and respiration are more pronounced in older and more diverse mixtures. The effects of plant mixtures on all microbial attributes are consistent across ecosystem types including natural forests, planted forests, planted grasslands, croplands, and planted containers. Our study underlines strong relationships between plant diversity and soil microorganisms across global terrestrial ecosystems and suggests the importance of plant diversity in maintaining belowground ecosystem functioning.


Assuntos
Bactérias/metabolismo , Biodiversidade , Biomassa , Aerobiose , Geografia , Solo , Microbiologia do Solo , Especificidade da Espécie
14.
Microb Pathog ; 129: 7-18, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30710672

RESUMO

Fungal diseases cause considerable damage to the economically important crops worldwide thus posing continuous threat to global food security. Management of these diseases is normally done via utilization of chemicals that have severe negative impact upon human health and surrounding ecosystems. Finding eco-friendly alternatives has led the researchers to focus towards biological control of fungal diseases through biocontrol agents such as antagonistic fungi (AF) and other microorganisms. AF include various genera of fungi that cure the fungal diseases on plants effectively. Furthermore, they play a regulatory role in various plant physiological pathways and interactions. AF are highly host specific having negligible effects on non-target organisms and have fast mass production capability. However, understanding the mechanisms of the effects of AF on plant diseases is a prerequisite for their effective utilization as biocontrol agent. Trichoderma is one of the most important fungal genera known for its antagonistic activity against disease causing fungal pathogens. Therefore, in this review, we have focused upon Trichoderma-mediated fungal diseases management via illustrating its taxonomy, important strains, biodiversity and mode of action. Furthermore, we have assessed the criteria to be followed for selection of AF and the factors influencing their efficiency. Finally, we evaluated the advantages and limitations of Trichoderma as AF. We conclude that effective AF utilization against fungal pathogens can serve as a safe strategy for our Planet.


Assuntos
Antibiose , Controle Biológico de Vetores/métodos , Doenças das Plantas/prevenção & controle , Plantas/microbiologia , Trichoderma/crescimento & desenvolvimento
15.
Sci Rep ; 9(1): 1049, 2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30705298

RESUMO

The contamination of soil and plants with heavy metals, which has detrimental influences on plant growth, water purification, and food safety, has emerged as a serious global issue. To better understand the spatial variations of contamination of heavy metals associated city development and land use types, we collected soil samples and Magnolia grandiflora branches to quantify lead (Pb) and cadmium (Cd) contents of the roadside, industrial, residential, and park greenbelts in Hefei City, China. We found that Pb content in soil was the highest in roadside greenbelts and the lowest in parks with industrial and residential greenbelts being intermediate, while Cd in soil was the highest in greenbelts close to city center and decreased with the distance to city center. Pb in M. grandiflora, however, did not differ among greenbelt types but decreased with distance to the city center. Cd in M. grandiflora was the highest in roadside and lowest in parks and also decreased with the distance to the city center. Across all greenbelt types and the distances to the city center, Pb and Cd contents were positively correlated in soil and plants. Our findings suggest that vehicle traffic, population density, and age of urbanization collectively contribute to soil and plant contamination of Pb and Cd.

16.
Glob Chang Biol ; 2019 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-30614140

RESUMO

The rapid global biodiversity loss has led to the decline in ecosystem function. Despite the critical importance of soil respiration (Rs) in the global carbon and nutrient cycles, how plant diversity loss affects Rs remains uncertain. Here we present a meta-analysis using 446 paired observations from 95 published studies to evaluate the effects of plant and litter mixtures on Rs and its components. We found that total Rs and heterotrophic respiration (Rh) were, on average, greater in plant mixtures than expected from those of monocultures. These mixture effects increased with increasing species richness (SR) in both plant and litter mixtures. While the positive effects of species mixtures remained similar over time for total Rs, they increased over time for Rh in plant mixtures but decreased in litter mixtures. Despite the wide range of variations in mean annual temperature, annual aridity index, and ecosystem types, the plant mixture effects on total Rs and Rh did not change geographically, except for a more pronounced increase of total Rs in species mixtures with reduced water availability. Our structural equation models suggested that the positive effects of SR and stand age on total and Rh were driven by increased plant inputs and soil microbial biomass. Our results suggest that plant diversity loss has ubiquitous negative impacts on Rs, one of the fundamental carbon-cycle processes sustaining terrestrial element cycling and ecosystem function.

17.
New Phytol ; 221(2): 807-817, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30256426

RESUMO

Plant stoichiometric coupling among all elements is fundamental to maintaining growth-related ecosystem functions. However, our understanding of nutrient balance in response to global changes remains greatly limited to plant carbon : nitrogen : phosphorus (C : N : P) coupling. Here we evaluated nine element stoichiometric variations with one meta-analysis of 112 global change experiments conducted across global terrestrial ecosystems and one synthesis over 1900 species observations along natural environment gradients across China. We found that experimentally increased soil N and P respectively enhanced plant N : potassium (K), N : calcium (Ca) and N : magnesium (Mg), and P : K, P : Ca and P : Mg, and natural increases in soil N and P resulted in qualitatively similar responses. The ratios of N and P to base cations decreased both under experimental warming and with naturally increasing temperature. With decreasing precipitation, these ratios increased in experiments but decreased under natural environments. Based on these results, we propose a new stoichiometric framework in which all plant element contents and their coupling are not only affected by soil nutrient availability, but also by plant nutrient demand to maintain diverse functions under climate change. This study offers new insights into understanding plant stoichiometric variations across a full set of mineral elements under global changes.


Assuntos
Elementos , Plantas/metabolismo , Dióxido de Carbono/metabolismo , Clima , Nitrogênio/análise , Fósforo/análise , Solo
18.
Tree Physiol ; 39(3): 417-426, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30239951

RESUMO

The introduction of species contributes to both ecological restoration and regional economics, while serving as a potential strategy to conserve species under rapid climate change. Despite an anticipated significant increase in temperature at high latitudes by the end of the 21st century, very few experimental migration trials have been conducted regarding large climate range changes. We employed a provenance trial by introducing a temperate sugar maple (Acer saccharum Marsh) of three provenances with a mean annual temperature of 3.0 °C in Manitoba, 4.2 °C in Quebec and 9.4 °C in Ontario, Canada, to 15.8 °C at an introduced site in subtropical China. We measured survival, growth, summer photosynthesis in the field and stress-resistance responses under a temperature gradient in growth chambers with first-year seedlings. We found that the Ontario provenance had the highest propensity for survival and growth, followed by the Quebec provenance, while the Manitoba provenance had the lowest. The photosynthetic parameters of the seedlings changed over time of the day, with the Ontario provenance having a higher photosynthesis rate and stomatal conductance than the Quebec and Manitoba provenances. Furthermore, the growth chamber results revealed that the Ontario provenance had the best physiological adjustment for self-protection from heat stress, followed by the Quebec and Manitoba provenances. Our results suggested that the change in climate range drove the survival and growth of introduced seedlings and that the tolerance to summer heat stress through physiological mechanisms was responsible for the success of species introduction, from a cold to a warm climate.


Assuntos
Acer/fisiologia , Temperatura Alta/efeitos adversos , Fotossíntese , Termotolerância , Acer/crescimento & desenvolvimento , Canadá , China , Mudança Climática , Espécies Introduzidas , Longevidade , Estações do Ano , Estresse Fisiológico
19.
Sci Total Environ ; 651(Pt 2): 1830-1838, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30317171

RESUMO

Transgenic Bacillus thuringiensis (Bt) crops have been widely planted, and the resulting environmental risks have attracted extensive attention. To foresee the impacts of Bt crops on soil quality, it is essential to understand how Bt crops alter the soil enzymatic activities and what the important influencing factors are. We compiled data from 41 published papers that studied soil enzymatic activities with Bt crops and their non-Bt counterparts. The results showed that dehydrogenase and urease significantly increased, but neutral phosphatase significantly decreased under Bt crop cultivations without Bt residues incorporation. The activities of dehydrogenase, ß-glucosidase, urease, nitrate reductase, alkaline phosphatase, and aryl sulfatase significantly increased under Bt crop cultivation with Bt residues incorporation. The response ratios of other enzymes were not significantly changed. Generally, the response ratios of soil enzymes were greater with Bt residues incorporation than those of Bt crop cultivations without Bt residues incorporation. Further, the response ratios of soil enzymes varied with Bt crop types and growth periods. It was the strongest under Bt cotton among Bt crops, and the significant responses usually appeared in the middle growth stages. The responses of soil enzymes ascribed more to the properties of Bt crops than to soil properties across sites. Given - significant responses of some soil enzymes to Bt crops, we recommended that soil environmental risks should be carefully evaluated over the transgenic crops.


Assuntos
Bactérias/enzimologia , Produtos Agrícolas/genética , Plantas Geneticamente Modificadas/genética , Microbiologia do Solo , Bacillus thuringiensis/genética , Produtos Agrícolas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/crescimento & desenvolvimento
20.
Glob Chang Biol ; 25(3): 1078-1088, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30589163

RESUMO

Soil net nitrogen mineralization rate (Nmin ), which is critical for soil nitrogen availability and plant growth, is thought to be primarily controlled by climate and soil physical and/or chemical properties. However, the role of microbes on regulating soil Nmin has not been evaluated on the global scale. By compiling 1565 observational data points of potential net Nmin from 198 published studies across terrestrial ecosystems, we found that Nmin significantly increased with soil microbial biomass, total nitrogen, and mean annual precipitation, but decreased with soil pH. The variation of Nmin was ascribed predominantly to soil microbial biomass on global and biome scales. Mean annual precipitation, soil pH, and total soil nitrogen significantly influenced Nmin through soil microbes. The structural equation models (SEM) showed that soil substrates were the main factors controlling Nmin when microbial biomass was excluded. Microbe became the primary driver when it was included in SEM analysis. SEM with soil microbial biomass improved the Nmin prediction by 19% in comparison with that devoid of soil microbial biomass. The changes in Nmin contributed the most to global soil NH4 + -N variations in contrast to climate and soil properties. This study reveals the complex interactions of climate, soil properties, and microbes on Nmin and highlights the importance of soil microbial biomass in determining Nmin and nitrogen availability across the globe. The findings necessitate accurate representation of microbes in Earth system models to better predict nitrogen cycle under global change.


Assuntos
Ciclo do Nitrogênio , Nitrogênio/química , Nitrogênio/metabolismo , Microbiologia do Solo , Solo/química , Biomassa , Clima , Ecossistema , Concentração de Íons de Hidrogênio , Modelos Teóricos , Plantas/metabolismo
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