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1.
Braz. j. biol ; 83: e243245, 2023. tab, graf
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-1278547

RESUMO

Abstract Although richness and distribution of woody species in the Cerrado physiognomies have been extensively studied, the shifts of woody species from savanna physiognomies to dry forests have not yet been addressed. Here, we investigate the effect of soil physical-chemical traits on the woody species turnover between adjacent cerrado stricto sensu and dry forest physiognomies. Woody species were surveyed, and soil and topographic variables measured, in 30 10×40 m plots systematically distributed, with 15 plots in each physiognomy. We found a spatially structured distribution of woody species, and differences of soil traits between cerrado stricto sensu and dry forest areas, mainly related to the aluminum saturation, base saturation, and available phosphorus. Aluminum saturation increased toward the savanna area, while base saturation increased toward the dry forest. Most woody species predominated in one physiognomy, such as Callisthene major in the cerrado stricto sensu and Anadenanthera colubrina in the dry forest. Only 20% of the species were widely distributed across both physiognomies or, not often, restricted to the intermediary values of the soil gradient. General results indicate that contrasting soil traits between cerrado stricto sensu and dry forest produce a strongly spatially organized and sharp transition in terms of species distribution between these physiognomies.


Resumo Embora a distribuição e a riqueza em espécies arbóreas nas fitofisionomias do Cerrado venham sendo bastante estudadas, a transição entre savanas e florestas deciduais ainda não foi abordada. Investigamos o efeito de características físico-químicas do solo sobre a distribuição de espécies arbóreas em região de contato entre cerrado sentido restrito e floresta estacional decidual (FED). As espécies arbóreas foram amostradas sistematicamente, e variáveis de topografia e características do solo foram medidas em 30 parcelas de 10×40 m, sendo 15 parcelas em cada fisionomia. A distribuição das espécies arbóreas foi espacialmente estruturada, e as características do solo diferiram entre as áreas de cerrado sentido restrito e FED, principalmente relacionadas à saturação de alumínio, saturação de bases e teores de fósforo. A saturação de alumínio aumentou em direção ao cerrado sentido restrito, enquanto a saturação de bases aumentou em direção à FED. A maioria das espécies arbóreas predominou em uma das fisionomias, como Callisthene major em cerrado sentido restrito e Anadenanthera colubrina em FED. Apenas 20% das espécies foram amplamente distribuídas em ambas as fisionomias ou, em poucos casos, restritas aos valores intermediários do gradiente de solo. Os resultados indicam um forte contraste de características do solo entre o cerrado sentido restrito e a FED, assim como uma transição acentuada e espacialmente organizada quanto à distribuição de espécies arbóreas.


Assuntos
Solo , Pradaria , Árvores , Brasil , Florestas
2.
An Acad Bras Cienc ; 94(3): e20201773, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36074403

RESUMO

Climate change (CC) and human footprint (HF) shape species spatial patterns and may affect the effectiveness of Protected Areas (PAs) network. Spatial patterns of threatened bird species of Subtropical-temperate hotspots in Southeastern South American grasslands are relevant biodiversity features to guide conservation policies. However, the PAs network covers less than 1% of grassland areas and does not overlap areas with the most suitable environmental conditions for threatened birds. Our aim was to find the most environmentally suitable areas for both current and future threatened birds (2050 and 2070) in Entre Ríos. We applied Systematic Conservation Planning protocols with Ecological Niche Models (ENMs) and ZONATION using distribution interaction function and HF as a cost. Then we overlapped binary maps to find priority areas among time periods. HF showed a more fragmented spatial configuration. The PAs network may include environmentally suitable conditions for threatened birds in CC scenarios and HF. We found areas that showed more connectivity in landscape prioritization over time and ensure high-quality environmental conditions for birds. We concluded that the effectiveness of the PAs network could be improved by overlapping priority areas. Our approach provides a knowledge base as a contribution to conservation-related decisions by considering HF and CC.


Assuntos
Mudança Climática , Pradaria , Animais , Biodiversidade , Aves , Conservação dos Recursos Naturais/métodos , Ecossistema , Espécies em Perigo de Extinção , Humanos
3.
Zootaxa ; 5125(3): 344-350, 2022 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-36101210

RESUMO

A new leafhopper species Stirellus pakistanicus Shah Duan sp. n. is described from Attock region of the Punjab province of Pakistan. Habitus photos and illustrations of male genitalia of the new species are provided. An updated checklist and a distribution map of the known species of Stirellus from Pakistan are also given.


Assuntos
Hemípteros , Animais , Genitália Masculina , Pradaria , Masculino , Paquistão
4.
Ying Yong Sheng Tai Xue Bao ; 33(7): 1871-1877, 2022 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-36052790

RESUMO

Biological soil crusts (biocrusts) are the common cover in arid and semiarid areas. Together with plants, biocrusts affect runoff and flow velocity. However, few studies have focused on the effects of the co-covering of plant and biocrust (plant+biocrust) on the flow velocity, with a knowledge gap in the study of driving factors for slope erosion in arid and semiarid areas. In this study, simulated rainfall experiments were used to investigate the effects of biocrust and three types of biocrusts (more cyanobacteria less moss, more moss less cyanobacteria, and moss) on the flow velocity of revegetated grassland in the hilly Loess Plateau. The results showed that plant and plant+biocrust significantly reduced flow velocity, with that of plants and plant+biocrust being 70.7% and 83.1% lower than bare soil. The reduction benefits of plant and biocrust on flow velocity were 70.7% and 12.4%, respectively, when they were co-covered. Biocrust composition under plant cover affected flow velocity. The reduction benefits of more cyanobacteria less moss, more moss less cyanobacteria, and moss crust on flow velocity were 11.5%, 12.4%, and 19.4%, respectively. There was a significant negative correlation between flow velocity and moss coverage and a significant positive correlation between flow velocity and cyanobacteria coverage. The relationship between moss cove-rage (x) and flow velocity (y) was y=-2.081x+0.03 (R2=0.469). The moss coverage was a key factor affecting the flow velocity of co-covering of plant and biocrust slope with similar plant coverage (40%±10%). In conclusion, biocrusts under plant cover significantly slowed flow velocity, and the effect magnitude was related to its composition, implying that the role of biocrusts should be considered in understanding the mechanism underlying slope erosion in revegetated grassland.


Assuntos
Briófitas , Cianobactérias , China , Ecossistema , Pradaria , Solo , Microbiologia do Solo
5.
Huan Jing Ke Xue ; 43(9): 4662-4673, 2022 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-36096607

RESUMO

MiSeq sequencing technology was used to investigate the bacterial compositions and diversities of active patch, non-active patch, recovered patch, and healthy alpine meadows so as to understand the changes in soil bacterial community diversity during altitude change and alpine meadow degradation. The relationship between bacterial diversity and environmental factors was analyzed using redundancy analysis (RDA). The results showed that the dominant bacterial phyla in the soil included Proteobacteria, Actinobacteriota, and Acidobacteriota in the study areas. The dominant bacterial genera that were identified via the MiSeq were RB41, Sphingomonas, and Bradyrhizobium. The relative abundance of these genera decreased with altitude increase and increased with the restoration progress of degraded patches but was significantly lower than that in the alpine meadow (P<0.05). The abundance of functional bacteria related to carbon fixation in degraded patches was higher than that in the healthy alpine meadow. The bacterial Chao1 index and species number in different types of degraded patches were significantly higher than those in the alpine meadow (P<0.05). The results of the RDA suggest that biological soil crust coverage and total nitrogen were the main influencing factors on dominant bacterial phyla at the altitude of 4013 m. Biomass, total nitrogen, and pH had a great influence on the dominant bacterial phyla at the altitude of 4224 m. Biomass and total potassium significantly affected the distribution of bacterial genera at the altitude of 4013 m. Sedge coverage and available nitrogen were the main influencing factors on bacterial dominant genera at the altitude of 4224 m. Biological soil crusts and pH had a great influence on bacterial diversities. The bacterial influence factors varied greatly at different altitude areas. Therefore, we should not only pay attention to the effect of alpine meadow degradation but also consider the effect of altitude in the study of bacterial diversity changes.


Assuntos
Pradaria , Solo , Bactérias/genética , Nitrogênio/análise , Rios , Solo/química , Microbiologia do Solo
6.
Artigo em Inglês | MEDLINE | ID: mdl-36018778

RESUMO

The order Solirubrobacterales is a deep-branching lineage within the phylum Actinomycetota. Most representatives have been isolated from terrestrial environments. A strain isolated from a grassland soil was found to be affiliated with this order and therefore characterized by a polyphasic approach. Cells of strain 0166_1T are Gram-positive, short rods, non-motile, non-spore-forming and divide by binary fission. A surface layer with protrusions covers the majority of the cells. Strain 0166_1T grows optimally around neutral to slightly alkaline pH (pH 7.1-7.9) and at temperatures between 24-36 °C in SSE/HD 1 : 10 medium. It grows optimally with 0-0.5% NaCl (w/v) but can withstand concentrations up to 5 %. The major fatty acids are C18 : 1 ω9c, C16 : 1 ω7c, C17 : 0 cyclo ω7c, C18 : 1 ω7c methyl and C19 : 0 cyclo ω9c. The major polar lipids are diphosphatidylglycerol, two unidentified phospholipids and one unidentified glycolipid. MK-7(H4) and MK-7(H2) are the predominant respiratory quinones. meso-2,6-Diaminopimelic acid is the diagnostic diamino acid in the cell-wall peptidoglycan. The G+C content for strain 0166_1T is 72.8 mol%. 16S rRNA gene sequence analysis indicated that this bacterium was related to Conexibacter arvalis KV-962T and Conexibacter stalactiti YC2-25T with 95.5 and 95.2 % sequence similarity, respectively. Based on the phenotypic, genomic and phylogenetic data, we propose the novel species Capillimicrobium parvum sp. nov. (type strain 0166_1T=DSM 104329T=LMG 29999T=CECT 9240T) of the novel genus Capillimicrobium gen. nov. within the novel family Capillimicrobiaceae fam. nov.


Assuntos
Pradaria , Solo , Bactérias , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Fosfolipídeos , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
7.
Annu Rev Phytopathol ; 60: 283-305, 2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36027939

RESUMO

Our understanding of the ecological interactions between plant viruses, their insect vectors, and their host plants has increased rapidly over the past decade. The suite of viruses known collectively as the yellow dwarf viruses infect an extensive range of cultivated and noncultivated grasses worldwide and is one of the best-studied plant virus systems. The yellow dwarf viruses are ubiquitous in cereal crops, where they can significantly limit yields, and there is growing recognition that they are also ubiquitous in grassland ecosystems, where they can influence community dynamics. Here, we discuss recent research that has explored (a) the extent and impact of yellow dwarf viruses in a diversity of plant communities, (b) the role of vector behavior in virus transmission, and (c) the prospects for impacts of climate change-including rising temperatures, drought, and elevated CO2-on the epidemiology of yellow dwarf viruses.


Assuntos
Afídeos , Luteovirus , Vírus de Plantas , Animais , Mudança Climática , Produtos Agrícolas , Ecossistema , Pradaria , Insetos Vetores , Doenças das Plantas
8.
PLoS One ; 17(8): e0272143, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35917373

RESUMO

Alpine meadows are strongly affected by climate change. Increasing air temperature prolongs the growing season and together with changing precipitation patterns alters soil temperature during winter. To estimate the effect of climate change on soil nutrient cycling, we conducted a field experiment. We transferred undisturbed plant-soil mesocosms from two wind-exposed alpine meadows at ~2100 m a.s.l. to more sheltered plots, situated ~300-400 m lower in the same valleys. The annual mean air temperature was 2°C higher at the lower plots and soils that were normally frozen at the original plots throughout winters were warmed to ~0°C due to the insulation provided by continuous snow cover. After two years of exposure, we analyzed the nutrient content in plants, and changes in soil bacterial community, decomposition, mineralization, and nutrient availability. Leaching of N and P from the soils was continuously measured using ion-exchange resin traps. Warming of soils to ~0°C during the winter allowed the microorganisms to remain active, their metabolic processes were not restricted by soil freezing. This change accelerated nutrient cycling, as evidenced by increased soil N and P availability, their higher levels in plants, and elevated leaching. In addition, root exudation and preferential enzymatic mining of P over C increased. However, any significant changes in microbial biomass, bacterial community composition, decomposition rates, and mineralization during the growing season were not observed, suggesting considerable structural and functional resilience of the microbial community. In summary, our data suggest that changes in soil temperature and snow cover duration during winter periods are critical for altering microbially-mediated processes (even at unchanged soil microbial community and biomass) and may enhance nutrient availability in alpine meadows. Consequently, ongoing climate change, which leads to soil warming and decreasing snow insulation, has a potential to significantly alter nutrient cycling in alpine and subalpine meadows compared to the current situation and increase the year-on-year variability in nutrient availability and leaching.


Assuntos
Pradaria , Solo , Mudança Climática , Ecossistema , Plantas , Estações do Ano , Neve , Solo/química , Microbiologia do Solo
9.
Science ; 377(6606): 603-608, 2022 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-35926033

RESUMO

Grasslands store approximately one third of the global terrestrial carbon stocks and can act as an important soil carbon sink. Recent studies show that plant diversity increases soil organic carbon (SOC) storage by elevating carbon inputs to belowground biomass and promoting microbial necromass contribution to SOC storage. Climate change affects grassland SOC storage by modifying the processes of plant carbon inputs and microbial catabolism and anabolism. Improved grazing management and biodiversity restoration can provide low-cost and/or high-carbon-gain options for natural climate solutions in global grasslands. The achievable SOC sequestration potential in global grasslands is 2.3 to 7.3 billion tons of carbon dioxide equivalents per year (CO2e year-1) for biodiversity restoration, 148 to 699 megatons of CO2e year-1 for improved grazing management, and 147 megatons of CO2e year-1 for sown legumes in pasturelands.


Assuntos
Sequestro de Carbono , Pradaria , Solo , Biomassa , Carbono/metabolismo , Plantas/metabolismo
10.
Science ; 377(6606): 594-598, 2022 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-35926035

RESUMO

Grasslands, which constitute almost 40% of the terrestrial biosphere, provide habitat for a great diversity of animals and plants and contribute to the livelihoods of more than 1 billion people worldwide. Whereas the destruction and degradation of grasslands can occur rapidly, recent work indicates that complete recovery of biodiversity and essential functions occurs slowly or not at all. Grassland restoration-interventions to speed or guide this recovery-has received less attention than restoration of forested ecosystems, often due to the prevailing assumption that grasslands are recently formed habitats that can reassemble quickly. Viewing grassland restoration as long-term assembly toward old-growth endpoints, with appreciation of feedbacks and threshold shifts, will be crucial for recognizing when and how restoration can guide recovery of this globally important ecosystem.


Assuntos
Recuperação e Remediação Ambiental , Pradaria , Animais , Biodiversidade , Florestas , Objetivos , Humanos
11.
Proc Natl Acad Sci U S A ; 119(35): e2204400119, 2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-35994662

RESUMO

Ecological niche differences are necessary for stable species coexistence but are often difficult to discern. Models of dietary niche differentiation in large mammalian herbivores invoke the quality, quantity, and spatiotemporal distribution of plant tissues and growth forms but are agnostic toward food plant species identity. Empirical support for these models is variable, suggesting that additional mechanisms of resource partitioning may be important in sustaining large-herbivore diversity in African savannas. We used DNA metabarcoding to conduct a taxonomically explicit analysis of large-herbivore diets across southeastern Africa, analyzing ∼4,000 fecal samples of 30 species from 10 sites in seven countries over 6 y. We detected 893 food plant taxa from 124 families, but just two families-grasses and legumes-accounted for the majority of herbivore diets. Nonetheless, herbivore species almost invariably partitioned food plant taxa; diet composition differed significantly in 97% of pairwise comparisons between sympatric species, and dissimilarity was pronounced even between the strictest grazers (grass eaters), strictest browsers (nongrass eaters), and closest relatives at each site. Niche differentiation was weakest in an ecosystem recovering from catastrophic defaunation, indicating that food plant partitioning is driven by species interactions, and was stronger at low rainfall, as expected if interspecific competition is a predominant driver. Diets differed more between browsers than grazers, which predictably shaped community organization: Grazer-dominated trophic networks had higher nestedness and lower modularity. That dietary differentiation is structured along taxonomic lines complements prior work on how herbivores partition plant parts and patches and suggests that common mechanisms govern herbivore coexistence and community assembly in savannas.


Assuntos
Dieta , Pradaria , Herbivoria , Mamíferos , Plantas , África , Animais , Comportamento Competitivo , Código de Barras de DNA Taxonômico , Dieta/estatística & dados numéricos , Dieta/veterinária , Fabaceae/classificação , Fabaceae/genética , Fezes , Mamíferos/classificação , Mamíferos/fisiologia , Plantas/classificação , Plantas/genética , Poaceae/classificação , Poaceae/genética , Chuva
12.
Sci Rep ; 12(1): 14672, 2022 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-36038609

RESUMO

The research was carried out on the territory of the Russian Federation in the forest-steppe region of the south Western Siberia (Omsk state), in the long-term (43 years) stationary experiment. Sprinkling was used for irrigation in the experiment. The number of different physiological groups of microorganisms, the cellulolytic activity of the soil, and nitrification capacity were determined under the sowing of an eight-field grain-grass crop rotation (perennial grasses (Bunias orientalis L. + Bromopsis inermis L. + Galega orientalis Lam. 6-8 years old), spring barley Hordeum vulgare Leyss.-variety Sasha). Immobilization processes predominated in the soil under the sowed crops, it contributes to the preservation of soil organic matter (mineralization coefficient SAA/MPA < 1). The highest transformation ratio of soil organic matter, i.e. increased conversion of plant residues into organic matter, was noted with applying nitrogen-phosphorus fertilizers (N60P60) under the barley. The combination of irrigation factors and the use of mineral fertilizers (N30-60P60) were contributed to the growth of the microorganisms' population, the amplification of decomposition of cellulose, and improvement of nitrification capacity in the soil. The perennial irrigation of the meadow-chernozem soil and the application of intensive technology of cultivation of crops in crop rotation stimulated the growth of the microorganisms' population and didn't detriment the ecological state of the soil.


Assuntos
Hordeum , Solo , Agricultura , Produtos Agrícolas , Fertilizantes , Pradaria , Nitrogênio/química , Solo/química
13.
Ying Yong Sheng Tai Xue Bao ; 33(8): 2153-2160, 2022 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-36043822

RESUMO

Based on community investigation data from grasslands on two different soil parent material types (loess and sand parent materials) and under three human utilization modes in the Saihan Ullah Reserve, we calculated human disturbance index (HDI) and biodiversity indices and analyzed the interactions between species diversity and degradation levels. The results showed that degradation status varied across different soil parent material types and human utilization modes, and that degradation levels of loess and sand parent materials both increased with the enhancement of human utilization intensification. HDI of loess parent material grasslands (mean value of 1.21) was lower than sand parent material grasslands (mean value of 1.48) in the same human utilization. Biodiversity indices declined with soil sandy degree and the utilization intensification. The mean values of Margarlef richness index, Shannon diversity index, Simpson dominance index and Pielou evenness index were between 1.57-4.27, 1.16-2.39, 0.76-0.87, and 0.71-0.80, respectively. The Margalef richness index, Shannon diversity index and Simpson dominance index decreased with increasing HDI, while Pielou evenness index increased. Overgrazing could lead to serious threat on both grasslands with soil parent material types, and the optimum utilization mode of loess and sand parent material grasslands were enclosure with mowing and seasonal grazing. In the future works of biodiversity conservation, it is important to consider the influence of both different soil patent material and human utilization modes of grassland. It is urgent to develop different utilization modes for grassland under different soil parent material types, which would enhance the matchness of grassland restoration and management with local conditions.


Assuntos
Pradaria , Solo , Biodiversidade , Humanos , Plantas/metabolismo , Areia
14.
Ying Yong Sheng Tai Xue Bao ; 33(8): 2161-2170, 2022 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-36043823

RESUMO

Nitrogen is the most limiting nutrient for ecosystems. The natural abundance of δ15N (15N/14N) can efficiently indicate ecosystem nitrogen cycling processes. We investigated the interannual variations in natural abundance of δ15N in soil-plant system and soil net nitrogen mineralization in a meadow steppe of Inner Mongolia. Results across the four sampling years (2017-2020) showed that the content of soil NO3--N (9.83-14.79 mg·kg-1) was significantly higher than that of NH4+-N (3.92-5.00 mg·kg-1) and that δ15N value of soil NH4+ (13.3‰-18.3‰) was significantly higher than that of NO3-(3.76‰-6.14‰). The δ15N value of soil NO3- was negatively correlated with soil NO3- content. The δ15N value of soil NH4+ was relatively higher in the dry years, while the δ15N value of soil NO3- significantly decreased in the wetter and drier years. Soil net mineralization and ammonification rates were significantly higher in the dry years than that of the wet years, while soil nitrification rates showed no correlation with annual precipitation. The δ15N values of plants were not related to that of soils, but nega-tively correlated with plant nitrogen content. Both δ15N values and nitrogen contents were significantly and positively correlated between the leguminous and non-leguminous plants, suggesting that legume could facilitate nitrogen uptake of non-leguminous plants. These results could provide supporting data for nitrogen cycling and their responses to changes in precipitation in grassland soil-plant systems.


Assuntos
Ecossistema , Solo , China , Pradaria , Nitrogênio/análise , Isótopos de Nitrogênio/análise , Plantas
15.
Molecules ; 27(15)2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35956824

RESUMO

Propolis is very popular for its beneficial health properties, such as antimicrobial activity and antioxidant effects. It is one of the most long-serving traditional medicines to mankind due to its interesting chemical diversity and therapeutic properties. The detailed chemical information of propolis samples is very necessary to guarantee its safety and for it to be accepted into health care systems. The phenolic profile of the hydroethanolic extract was determined using HPLC-DAD, and the antioxidant was evaluated using five complementary methods. Triterpenoids were isolated using column chromatography and characterized using 1H NMR and 13C NMR. The effects of the extract and the isolated compounds on quorum sensing mediated processes and biofilm formation in bacteria were evaluated. Protocatechic acid (40.76 ± 0.82 µg/g), 4-hydroxybenzoic acid (24.04 ± 0.21 µg/g), vanillic acid (29.90 ± 1.05 µg/g), quercetin (43.53 ± 1.10 µg/g), and luteolin (4.44 ± 0.48 µg/g) were identified and quantified. The extract showed good antioxidant activity in the DPPH•, ABTS•+, CUPRAC, and metal chelating assays, and this antioxidant effect was confirmed by cyclic voltammetry. 27-Hydroxymangiferonic acid (1), Ambolic acid (2), and Mangiferonic acid (3) were isolated from anti-quorum sensing activity at MIC, and it was indicated that the most active sample was the extract with inhibition diameter zone of 18.0 ± 1.0 mm, while compounds 1, 2, and 3 had inhibition zones of 12.0 ± 0.5 mm, 9.0 ± 1.0 mm, and 12.3 ± 1.0 mm, respectively. The samples inhibited the P. aeruginosa PA01 swarming motility at the three tested concentrations (50, 75, and 100 µg/mL) in a dose-dependent manner. The propolis extract was able to inhibit biofilm formation by S. aureus, E. coli, P. aeruginosa, C. albicans, and C. tropicalis at MIC concentration. Compound 1 proved biofilm inhibition on S. aureus, L. monocytogenes, E. faecalis, E. coli, and C. tropicalis at MIC and MIC/2; compound 2 inhibited the formation of biofilm at MIC on S. aureus, E. faecalis, E. coli, S. typhi, C. albicans, and C. tropicalis; and compound 3 inhibited biofilm formation on E. faecalis, E. coli, C. albicans, and C. tropicalis and further biofilm inhibition on E. coli at MIC/4 and MIC/8. The studied propolis sample showed important amounts of cycloartane-type triterpene acids, and this indicates that there can be significant intra-regional variation probably due to specific flora within the vicinity. The results indicate that propolis and its compounds can reduce virulence factors of pathogenic bacteria.


Assuntos
Própole , Triterpenos , Antibacterianos/farmacologia , Antioxidantes/farmacologia , Bactérias , Biofilmes , Camarões , Candida albicans , Misturas Complexas/farmacologia , Escherichia coli , Pradaria , Testes de Sensibilidade Microbiana , Fenóis/farmacologia , Própole/química , Própole/farmacologia , Pseudomonas aeruginosa , Staphylococcus aureus , Triterpenos/farmacologia
17.
BMC Plant Biol ; 22(1): 396, 2022 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-35964004

RESUMO

BACKGROUND: N (nitrogen) and P (phosphorus) play important roles in plant growth and fitness, and both are the most important limiting factors that affect grassland structure and function. However, we still know little about plant physiological responses to N and P enrichment in alpine grassland of the Qinghai-Tibetan Plateau. In our experiment, five dominant common herbaceous species were selected and their photosynthetic parameters, leaf N content, and aboveground biomass were measured. RESULTS: We found that species-specific responses to N and P enrichment were obvious at individual level. N addition (72 kg Nha-1 yr-1), P addition (36 kg Pha-1 yr-1) and NP addition (72 kg Nha-1 yr-1and 36 kg P ha-1 yr-1, simultaneously) significantly promoted net photosynthetic rate of Leymus secalinus. Differential responses also existed in the same functional groups. Responses of forb species to the nutrients addition varied, Aconitum carmichaeli was more sensitive to nutrients addition including N addition (72 kg Nha-1 yr-1), P addition (36 kg Pha-1 yr-1) and NP addition (72 kg Nha-1 yr-1and 36 kg P ha-1 yr-1). Responses of plant community photosynthetic traits were not so sensitive as those of plant individuals under N and P enrichment. CONCLUSIONS: Our findings highlighted that photosynthetic responses of alpine plants to N and P enrichment were species-specific. Grass species Leymus secalinus had a higher competitive advantage compared with other species under nutrient enrichment. Additionally, soil pH variation and nutrients imbalance induced by N and P enrichment is the main cause that affect photosynthetic traits of plant in alpine steppe of the Qinghai-Tibetan Plateau.


Assuntos
Pradaria , Plantas , Fotossíntese , Poaceae/fisiologia , Solo/química , Tibet
18.
Proc Natl Acad Sci U S A ; 119(36): e2210433119, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36037376

RESUMO

The widespread extirpation of megafauna may have destabilized ecosystems and altered biodiversity globally. Most megafauna extinctions occurred before the modern record, leaving it unclear how their loss impacts current biodiversity. We report the long-term effects of reintroducing plains bison (Bison bison) in a tallgrass prairie versus two land uses that commonly occur in many North American grasslands: 1) no grazing and 2) intensive growing-season grazing by domesticated cattle (Bos taurus). Compared to ungrazed areas, reintroducing bison increased native plant species richness by 103% at local scales (10 m2) and 86% at the catchment scale. Gains in richness continued for 29 y and were resilient to the most extreme drought in four decades. These gains are now among the largest recorded increases in species richness due to grazing in grasslands globally. Grazing by domestic cattle also increased native plant species richness, but by less than half as much as bison. This study indicates that some ecosystems maintain a latent potential for increased native plant species richness following the reintroduction of native herbivores, which was unmatched by domesticated grazers. Native-grazer gains in richness were resilient to an extreme drought, a pressure likely to become more common under future global environmental change.


Assuntos
Biodiversidade , Bison , Pradaria , Animais , Bovinos , Plantas
19.
J Environ Manage ; 320: 115889, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35932732

RESUMO

Grasslands are now facing a continuously increasing supply of nitrogen (N) fertilizers, resulting in alterations in ecosystem functioning, including changes in carbon (C) and water cycling. Mowing, one of the most widely used grassland management techniques, has been shown to mitigate the negative impacts of increased N availability on species richness. However, knowledge of how N addition and mowing, alone and/or in combination, affect ecosystem-level C fluxes and water use efficiency (WN) is still limited. We experimentally manipulated N fertilization (0 and 10 g N m-2 yr-1) and mowing (once per year at the end of the growing season) following a randomized block design in a meadow steppe characterized by salinization and alkalinization in northeastern China. We found that, compared to the control plots, N addition, mowing, and their interaction increased net ecosystem CO2 exchange by 65.1%, 14.7%, and 133%, and WN by 40.7%, 18.5%, and 96.1%, respectively. Nitrogen enrichment also decreased soil pH, which resulted in greater aboveground biomass (AGB). Moreover, N addition indirectly increased AGB by inducing changes in species richness. Our results indicate that mowing enhances the positive effects of N addition on ecosystem C fluxes and WN. Therefore, appropriate grassland management practices are essential to improve ecosystem C sequestration, WN, and mitigate future species diversity declines due to ecosystem eutrophication.


Assuntos
Ecossistema , Nitrogênio , Carbono/análise , China , Pradaria , Nitrogênio/análise , Solo/química , Água/análise
20.
J Environ Manage ; 320: 115791, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35932742

RESUMO

Grazing may represent a major threat to biodiversity in arid grasslands. The increasing use of grasslands for solar parks may represent a new important threat. No study has investigated the effects of solar parks on soil insects. Tenebrionids are a major component of the arthropod fauna of grasslands of central Asia. These ecosystems are threatened by grazing and increasing land use for solar parks. Aim of this work was to investigate the effects of grazing and solar panels on tenebrionids in arid grasslands (desert steppe) in China by comparing their community structure in ungrazed, heavily grazed, and solar park sites. Beetles were sampled by pitfall traps, and sites were compared for abundance and diversity (Hill numbers). All sites were characterized by simple, strongly dominated tenebrionid communities. Species proportions varied among sites. Grazing negatively influenced overall abundance, but did not alter species proportions; by contrast, solar panels had no effect on the average abundance, but reduced the proportion of the most abundant species. Compared with the other two sites, the solar park was characterized by a higher plant biomass and lower temperatures. A major availability of resources and less harsh conditions in the solar park might have a role in reducing the dominance of the most abundant species, allowing other species to attain higher abundances. This led to a more balanced community structure, with higher values of diversity. Although neither grazing nor solar panel installation modified radically tenebrionid species-abundance distribution or diversity, grazing and solar panel installation had different effects in species abundances and their impact might amplify the effect of other disturbance factors such as the ongoing climate change.


Assuntos
Besouros , Ecossistema , Animais , Biodiversidade , Biomassa , Pradaria , Solo/química
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