Tannase is a biotechnologically important enzyme that can be produced during fungal fermentation of organic matter. The Caatinga is an exclusive Brazilian ecosystem that has been largely unexplored by science, particu...Tannase is a biotechnologically important enzyme that can be produced during fungal fermentation of organic matter. The Caatinga is an exclusive Brazilian ecosystem that has been largely unexplored by science, particularly its filamentous fungal diversity. This study evaluated the diversity of filamentous fungi in the Caatinga soils of Pernambuco, Brazil, and their potential for tannase production by solid-state fermentation (SSF) of mango (Mangifera indica L.) and Surinam cherry (Eugenia uniflora L.) leaves. A total of 4711 isolates were obtained, 2090 during the rainy seasonand 2621 during the dry season. The isolates belonged to 18 genera and 66 species, with Aspergillus and Penicillium having the highest species richness. The dry season had a higher diversity index. Aspergillus was the dominant genus, and A. flavus, A. sclerotiorum, and A. ochraceus the most abundant species. A representative of each species was tested for tannase production using dried mango and Surinam cherry leaves as substrates;the leaves contained 14.28 and 7.0 g/L tannin, respectively. Most fungal species produced tannase, but the highest yields were obtained when mango leaves were used as substrate for Penicillium restrictum (accession URM 6044), Aspergillus flavofurcatus (URM 6142), and A. stromatoides (URM 6609), which produced 104.16, 87.51, and 81.83 U/mL tannase, respectively. These yields exceeded previously published reports. Filamentous fungi from Caatinga soils have great potential for producing tannase by SSF, and low-cost mango leaves make excellent substrate.展开更多
The use of medicinal plants as therapeutic and economic resources has been on the rise in recent years. In Brazil, however, increasing doubt is being cast on the quality of these products, owing to the prevalence of a...The use of medicinal plants as therapeutic and economic resources has been on the rise in recent years. In Brazil, however, increasing doubt is being cast on the quality of these products, owing to the prevalence of adulteration and fraud. Solar radiation can cause serious damage to human skin, as a result, mostly, of ultraviolet light, which is a cause of skin cancer. Photoprotective substances are capable of absorbing, reflecting, or refracting ultraviolet radiation and thus protecting skin from exposure to sunlight. The present study aimed to characterize samples and examine the phytochemical profile and photoprotective potential of bark and leaves of Erythrina velutina Willd. The samples underwent five extraction methods using 80% ethanol. The phenolic content was measured using spectrophotometry. Antioxidant activity was examined using the DPPH and the photoprotective properties of the plant extracts were assessed using the method developed by Mansur. There was a quantitative difference in some groups of metabolites, with higher levels of tannin in the bark and of flavonoids in the leaves. The latter showed greater DPPH free radical scavenging capacity than the bark, although higher levels of SPF were obtained from the bark, with no statistically significant differences between methods. The results indicate that Erythrina velutina Willd. has potential as a photoprotector.展开更多
Rocky outcrops function as island-like environmental filters and pivotal ecological refuges for local and regional biodiversity,with their inherent topographic and microclimatic dynamics directly shaping vegetation co...Rocky outcrops function as island-like environmental filters and pivotal ecological refuges for local and regional biodiversity,with their inherent topographic and microclimatic dynamics directly shaping vegetation composition and distribution across slopes.This study inventoried the flora of a rocky outcrop slope within Brazil's Caatinga biome,a seasonally dry tropical forest,to analyze species distribution patterns and their relationship with microtopographic conditions.The slope was stratified into base,middle and top segments according to slope gradient,with specimens collected over seven months of field expeditions,followed by taxonomic processing to compile a floristic inventory.The survey documented 60 species,53 genera,and 28 families,with Fabaceae,Euphorbiaceae,and Malvaceae emerging as the most representative families;herbaceous species dominated,followed by trees and shrubs.Species richness declined along the topographic gradient as altitude increased,with 43%of flora comprising species widespread across Brazilian biomes and 20%endemic to the Caatinga.Variations in species distribution across slope positions suggest that topographic heterogeneity may drive distinct pedological and microclimatic conditions,directly influencing vegetation dynamics in rock outcrops.These findings underscore the role of microtopography in structuring plant communities in harsh environments.展开更多
Our work aimed to test the hypothesis that soil microscale heterogeneity act as a community ecological driver,increasing diversity and promoting structural shifts on the Seasonally Dry Tropical Forest(SDTF)tree commun...Our work aimed to test the hypothesis that soil microscale heterogeneity act as a community ecological driver,increasing diversity and promoting structural shifts on the Seasonally Dry Tropical Forest(SDTF)tree community.We evaluated the relationship between microscale edaphic variations and floristic–structural patterns of tree communities in a SDTF fragment located in the southern end of the Brazilian Caatinga domain.Vegetation and soil data were obtained through 27 sample units of 400 m2(20 m 920 m),within each one we measured and identified at species level all arboreal individuals with Circumference at the Breast Height greater or equal to 10 cm,and also collected the soil samples.Through the data we evaluated soil variation influence on the tree community structural and floristic patterns trough generalized linear models.Soil explained the small-scale structural and floristic variations,contributing significantly to biomass,sprouting and to floristic relationships between sample units.It was also observed a possible relation of the result with the Caatinga domain biogeographic history,due the presence of Sedimentary Caatinga species,which are not expected for the study region.Soil plays an important role in driving small-scale complexity and diversity of SDTF,but we also suggest that Caatinga biogeographic events have influence on the high heterogeneity patterns.展开更多
Plant macronutrient distribution in podzolized sands of the Amazon caatinga has received attention in several studies;however, the distribution of micronutrients has not been assessed. Soil micronutrient availability ...Plant macronutrient distribution in podzolized sands of the Amazon caatinga has received attention in several studies;however, the distribution of micronutrients has not been assessed. Soil micronutrient availability has been hypothesized to reflect contrasting habitat characteristics as well as fundamental differences in substrate, and leaf micronutrient composition may reflect the macronutrient content needed to maintain balance for leaf cell functions. In this study, soil and leaf samples were obtained in a toposequence (valley, slope, and mound). Available soil micro- and macronutrients as well as total leaf content were measured by inductively coupled plasma-atomic emission spectrometer and mass spectroscopy. Soil Zn (-1) and B (-1) as well as Cu (-1) levels were very low. Soil Mn was low in the valleys and slopes (0.62-0.87 mg·kg-1), but higher in the mound (6.59 mg·kg-1). Soil Fe (11.48-21.13 mg·kg-1) was well above the critical level in all of the habitats. Leaf micronutrients Cu, B, Zn, and Fe were below the critical levels for tropical crops of 3-7, 20-70, 15-20, and 72 mg·kg-1, respectively. Leaf Mn (88 mg·kg-1) and Al (<50 mg·kg-1) were below the accumulators level. A strong relationship between leaf micro- and macronutrients suggests the maintenance of a homeostatic elemental composition, which may favour photosynthetic function. Therefore, the local distribution of species may be shaped by their abilities to maintain a balance of micronutrient collected through roots under critically low levels of available Zn, B, and Cu whilst excluding potentially deleterious ions of Mn, Fe, and Al.展开更多
Soils(Leptosols or Epileptic Regosols)with lithic contact at a depth of 50 cm occupy almost 20%of the Brazilian semi-arid region.These lithic soils are susceptible to erosion due to faster saturation of water-holding ...Soils(Leptosols or Epileptic Regosols)with lithic contact at a depth of 50 cm occupy almost 20%of the Brazilian semi-arid region.These lithic soils are susceptible to erosion due to faster saturation of water-holding capacity during rainfall,which accelerates the beginning of runoff.However,erosion traits of lithic soils in the semi-arid region of Brazil are less studied.The aim of this study was to characterize the soil and landscape attributes in areas with Neossolos Litólicos(Entisols)in the Caatinga biome to identify region of high susceptibility to erosion.Results showed that the soils were characterized by a sandy texture,soil structure with poor development and low content of organic carbon.These attributes increase susceptibility to erosion and reduce water storage capacity,especially in the states of Cearáand Sergipe.In these states,the content of rock fragments in the soil reaches 790 g/kg.High contents of silt and fine sand,high silt/clay ratio,predominance of Leptosols and strong rainfall erosivity were observed in Piauíand northwestern Ceará.A very high degree of water erosion was observed in the states of Pernambuco and Paraíba.Despite the low degree of erosion observed in the state of Bahia,it is highly susceptible to erosion due to the predominance of very shallow soils,rugged relief and high values of rainfall erosivity.Lower vulnerability was observed in the state of Alagoas because of its more smoothed relief,greater effective soil depth,thicker A horizon of soil and lower rainfall erosivity.In general,the characteristics that intensify the susceptibility to erosion in the Caatinga biome are those soil structures with poor development or without aggregation,low contents of organic carbon,high contents of silt and fine sand,high values of silt/clay ratio and rugged relief in some regions.This study collected information contributing to a better characterization of soils with lithic contact in the semi-arid region of Brazil.In addition,regions with a higher susceptibility to erosion were identified,revealing insights that could help develop strategies for environmental risk mitigation.展开更多
The volumetric variability of dry tropical forests in Brazil and the scarcity of studies on the subject show the need for the development of techniques that make it possible to obtain adequate and accurate wood volume...The volumetric variability of dry tropical forests in Brazil and the scarcity of studies on the subject show the need for the development of techniques that make it possible to obtain adequate and accurate wood volume estimates.In this study,we analyzed a database of thinning trees from a forest management plan in the Contendas de SincoráNational Forest,southwestern Bahia State,Brazil.The data set included a total of 300 trees with a trunk diameter ranging from 5 to 52 cm.Adjustments,validation and statistical selection of four volumetric models were performed.Due to the difference in height values for the same diameter and the low correlation between both variables,we do not suggest models which only use the diameter at breast height(DBH)variable as a predictor because they accommodate the largest estimation errors.In comparing the best single entry model(Hohenald-Krenn)with the Spurr model(best fit model),it is noted that the exclusion of height as a predictor causes the values of 136.44 and 0.93 for Akaike information criterion(AIC)and adjusted determination coefficient(R2 adj),which are poorer than the second best model(Schumacher-Hall).Regarding the minimum sample size,errors in estimation(root mean square error(RMSE)and bias)of the best model decrease as the sample size increases,especially when a larger number of trees with DBH≥15.0 cm are randomly sampled.Stratified sampling by diameter class produces smaller volume prediction errors than random sampling,especially when considering all trees.In summary,the Spurr and Schumacher-Hall models perform better.These models suggest that the total variance explained in the estimates is not less than 95%,producing reliable forecasts of the total volume with shell.Our estimates indicate that the bias around the average is not greater than 7%.Our results support the decision to use regression methods to build models and estimate their parameters,seeking stratification strategies in diameter classes for the sample trees.Volume estimates with valid confidence intervals can be obtained using the Spurr model for the studied dry forest.Stratified sampling of the data set for model adjustment and selection is necessary,since we find significant results with mean error square root values and bias of up to 70%of the total database.展开更多
Management evaluation of Panicum maximum cv. massai (Massai guineagrass) under deferment contributes as a strategic reserve of forage in the Brazilian semi-arid region. The objective of this study was to evaluate biom...Management evaluation of Panicum maximum cv. massai (Massai guineagrass) under deferment contributes as a strategic reserve of forage in the Brazilian semi-arid region. The objective of this study was to evaluate biomass production and nutritive value of massai guineagrass in an area of thinned caatinga vegetation in two deferment periods (60 and 90 days after plot-leveling cut) and four use periods (30, 60, 90 and 120 days after the end of the rain season), in a random blocks design arranged in a split-plot (2 × 4), with three replications. Extending the deferment period of massai guineagrass promoted elevation of the biomass components, but compromised the pasture quality due to increasing stem biomass. The massai guineagrass deferred 30 days after raining season started and should use 90 days after raining season ended to ensure a forage supply of appropriate nutritional value. The increase in relative air humidity and the occurrence of rainfall after water restriction stimulate regrowth, resulting in improved nutritional value of the grass.展开更多
The Caatinga biome is an important ecosystem in the semi-arid region of Brazil.It has significantly degraded due to human activities and is currently a region undergoing desertification.Thus,monitoring the variation i...The Caatinga biome is an important ecosystem in the semi-arid region of Brazil.It has significantly degraded due to human activities and is currently a region undergoing desertification.Thus,monitoring the variation in the Caatinga biome has become essential for its sustainable development.However,traditional methods for estimating aboveground biomass(AGB)are time-consuming and destructive.Remote sensing,such as optical and radar imaging,can estimate and correlate with vegetation.Nevertheless,radar imaging is still a novelty to be applied in estimating the AGB of this biome,which is an area with little research.Therefore,this study aimed to use Sentinel-1 images to estimate the AGB of the Caatinga biome in Sergipe State(northeastern Brazil)and to verify its influencing factors.Nineteen sample plots(30 m×30 m)were selected,and the stems of individuals with a circumference at breast height(1.3 m above the ground)equal to or greater than 6.0 cm were measured,and the AGB through an allometric equation was estimated.The Sentinel-1 images from 3 different periods(green,intermediate,and dry periods)were used to consider the phenological conditions of the Caatinga biome.All the pre-processing and extraction of attributes(co-polarized VV(vertical transmit and vertical receive),cross-polarized VH(vertical transmit and horizontal receive),and band ratio VH/VV backscatter,radar vegetation index,dual polarization synthetic aperture radar(SAR)vegetation index(DPSVI),entropy(H),and alpha angle(α))were performed with Sentinel’s Application Platform.These attributes were used to estimate the AGB through simple and multiple linear regressions and evaluated by the coefficients of determination(R2),correlation(r),and root mean squared error(RMSE).The results showed that the attributes individually had little ability to estimate the AGB of the Caatinga biome in the three periods.Combined with multiple regression,we found that the intermediate period presented the equation with the best results among the observed and estimated variables(R^(2)=0.73;r=0.85;RMSE=8.33 Mg/hm^(2)),followed by the greenness period(R2=0.72;r=0.85;RMSE=8.40 Mg/hm^(2)).The attributes contributing to these equations were VH/VV,DPSVI,H,α,and co-polarized VV for the green period and cross-polarized VH for the intermediate period.The study showed that the Sentinel-1 images could be used to estimate the AGB of the Caatinga biome in the green and intermediate phenological periods since the SAR attributes highly correlated with the estimated variable(i.e.,AGB)through multiple linear equations.展开更多
The mixed forests of the upper Rio Negro at the northern of the Amazon basin grow in oxisol soils that are extremely infertile. These areas exhibit deficiencies in several macro-nutrients, and may also be characterize...The mixed forests of the upper Rio Negro at the northern of the Amazon basin grow in oxisol soils that are extremely infertile. These areas exhibit deficiencies in several macro-nutrients, and may also be characterized by the shortage or toxic excess of some micronutrients. The overall goal of this research is to collect more comprehensive information regarding the micronutrient composition of the upper Rio Negro forests as well as discern the relationship between leaf micro- and macro-nutrients that may contribute to the homeostasis and balance of the ionome. Firstly, the nutrient composition within the oxisol soil and leaf tissues of two top canopy tree species from the mixed forests was determined. We then analyzed the relationship between leaf micronutrient composition with N and P levels of the two species and that of species inhabiting the Amazon caatinga. Extractable soil Zn, B, Mn and Cu were very low in the mixed forest. In contrast, Fe and Al levels were potentially toxic. The analysis of leaf N/P ratios revealed for the first time the co-limitation of N and P in the mixed forest. This contrasts with species from the adjacent Amazon caatinga toposequence that are characterized by strong N limitation. All micronutrients within leaves of species inhabiting the mixed forest were also found to have low concentrations. Moreover, Fe and Al were detected at concentrations well below those reported for accumulator species. This suggested that leaf ion homeostasis was maintained under potentially toxic soil Fe and Al conditions. Leaf micronutrient (Fe, Zn and B) contents mirrored that of leaf N and P contents, and comparable Fe/N, Fe/P, Zn/N, Zn/P, B/N as well as B/P ratios were found across species and forest types. Therefore, forest species exhibited the capability to maintain leaf nutrient balances under soil conditions with deficient or toxic levels of micronutrients.展开更多
This paper outlines procedures to analyze the desertification processes in the semi-arid Seridó Region (NE Brazil). Using the Geosystem theory, the detection of desertification areas was based on environmental in...This paper outlines procedures to analyze the desertification processes in the semi-arid Seridó Region (NE Brazil). Using the Geosystem theory, the detection of desertification areas was based on environmental indices, digital image processing in multispectral analysis and Geographic Information System (GIS).The first step was to treat the rainfall data and NDVI satellite Modis, aiming at identifying areas which do not present vegetation cover, even during the rainy seasons.The second step was to work on a regional scale using Landsat ETM + images (2000-2005) and data collected in the field, as the evaluations of exposed surfaces, that together with MDT/SRTM-NASA and thematic maps, allowed to classify the altitude and slope of the relief, soils type, different morphologies and geology, and correlate them with the areas susceptible to desertification process. The integration of the georeferenced data, related to these indicators, allowed the identification of five different levels of susceptibility to desertification (very high, high, moderate, low and very low), and the geographic domain of each class. Based on the analysis of the dynamics of the vegetation cover, we can establish that the main results refer that there is a decrease of the biomass at the region, associated with the dense caatinga vegetation areas, but more important, with the scrub and degraded areas.展开更多
Species of the genus Erythrina are frequently used as ornamental plants and in projects to restore degraded areas. Also, extracts from its shoots and stems are popularly used as a herbal medicine with validated activi...Species of the genus Erythrina are frequently used as ornamental plants and in projects to restore degraded areas. Also, extracts from its shoots and stems are popularly used as a herbal medicine with validated activity on the central nervous system. The objective of this study was to evaluate E. mulungu and E. velutina seed germination and seedling development potential aiming commercial scale production of those species. Seeds stored for one or twelve months at 10°C ± 2°C were sown in sand, soil or Plantmax? substrates and evaluated for germination and seedling development. Subsequently, seedlings sprouted in Plantmax? were transferred to polyethylene bags and kept in greenhouse, under direct sunlight for plant development (plant height, stem diameter and root length pivoting) evaluations. Four-month-old plantlets were transplanted to the field and after a period of one year the collar diameter and shoot height (of each plant were measured. Seed germination rates of both species grown in soil and in Plantmax? were significantly high (over 80%). Storing seeds for 1 month did not inhibit germination. However, seeds stored for twelve months had germination reduced by more than a quarter. The development of plants in greenhouse and in the field was satisfactory, indicating the viability of producing E. mulungu and E. velutina on a commercial scale, in order to meet the expanding market demand for herbal medicines.展开更多
Introduction:Here,we compare the arbuscular mycorrhizal fungal(AMF)community composition in soils from the root zone of the exotic invasive species Prosopis juliflora(EXO soils)and soils from the root zone of the nati...Introduction:Here,we compare the arbuscular mycorrhizal fungal(AMF)community composition in soils from the root zone of the exotic invasive species Prosopis juliflora(EXO soils)and soils from the root zone of the native species Mimosa tenuiflora(NAT soils)from five locations in the Brazilian tropical seasonal dry forest,Paraíba,Brazil,using morphological analyses.Results:AMF community composition in EXO and NAT soils were dissimilar.Available phosphorus,diversity index,spore abundance,and species richness were the main factors differing between the EXO and NAT soils.In general,the most dominant order present in the soils were Glomerales(44.8%)and Gigasporales(41.4%).The most abundant AMF genus in all studied soils was Funneliformis.Conclusions:Differences in AMF community composition were associated with(1)differences in the dominant plant species(P.juliflora vs.M.tenuiflora)and(2)changes in soil chemical factors(soil,pH,total organic carbon,total nitrogen,and available P)in EXO soils.These results contribute to a deeper view of the AMF communities in exotic soils and open new perspectives for ecological processes involving AMF species and exotic plant species in the Brazilian tropical seasonal dry forest.展开更多
Aims Understanding succession in tropical forest is an important aspect of vegetation science,but to date,successional processes in sea-sonally dry tropical forests(SDtFs)have received much less atten-tion than evergr...Aims Understanding succession in tropical forest is an important aspect of vegetation science,but to date,successional processes in sea-sonally dry tropical forests(SDtFs)have received much less atten-tion than evergreen humid tropical forests.We aim to fill this knowledge gap.Methods We investigated vegetation succession in SDtF areas consisting of three different successional stages(early,intermediate,late),and a SDtF-savanna ecotone in the municipal district of Juramento,north of Minas Gerais State,Brazil.Using twelve 400 m2 plots in each area,we compared vegetation parameters and structural variables(absolute density and basal area)and examined the floristic composition of the tree component to find gradients of change.Important Findings We found evidence of species turnover along a successional gradi-ent,with the intermediate stage showing the highest species rich-ness and diversity.this was accompanied with a significant increase in the number of tree individuals and basal area from the early to intermediate successional stage.However,the intermediate and late SDtF successional stages were more similar in structure and floristics.the ecotone was the most species rich and was similar to the intermediate SDtF and early successional stage in species richness and floristic composition respectively.these results will have implications for guiding SDtF management and recovery programs.展开更多
文摘Tannase is a biotechnologically important enzyme that can be produced during fungal fermentation of organic matter. The Caatinga is an exclusive Brazilian ecosystem that has been largely unexplored by science, particularly its filamentous fungal diversity. This study evaluated the diversity of filamentous fungi in the Caatinga soils of Pernambuco, Brazil, and their potential for tannase production by solid-state fermentation (SSF) of mango (Mangifera indica L.) and Surinam cherry (Eugenia uniflora L.) leaves. A total of 4711 isolates were obtained, 2090 during the rainy seasonand 2621 during the dry season. The isolates belonged to 18 genera and 66 species, with Aspergillus and Penicillium having the highest species richness. The dry season had a higher diversity index. Aspergillus was the dominant genus, and A. flavus, A. sclerotiorum, and A. ochraceus the most abundant species. A representative of each species was tested for tannase production using dried mango and Surinam cherry leaves as substrates;the leaves contained 14.28 and 7.0 g/L tannin, respectively. Most fungal species produced tannase, but the highest yields were obtained when mango leaves were used as substrate for Penicillium restrictum (accession URM 6044), Aspergillus flavofurcatus (URM 6142), and A. stromatoides (URM 6609), which produced 104.16, 87.51, and 81.83 U/mL tannase, respectively. These yields exceeded previously published reports. Filamentous fungi from Caatinga soils have great potential for producing tannase by SSF, and low-cost mango leaves make excellent substrate.
文摘The use of medicinal plants as therapeutic and economic resources has been on the rise in recent years. In Brazil, however, increasing doubt is being cast on the quality of these products, owing to the prevalence of adulteration and fraud. Solar radiation can cause serious damage to human skin, as a result, mostly, of ultraviolet light, which is a cause of skin cancer. Photoprotective substances are capable of absorbing, reflecting, or refracting ultraviolet radiation and thus protecting skin from exposure to sunlight. The present study aimed to characterize samples and examine the phytochemical profile and photoprotective potential of bark and leaves of Erythrina velutina Willd. The samples underwent five extraction methods using 80% ethanol. The phenolic content was measured using spectrophotometry. Antioxidant activity was examined using the DPPH and the photoprotective properties of the plant extracts were assessed using the method developed by Mansur. There was a quantitative difference in some groups of metabolites, with higher levels of tannin in the bark and of flavonoids in the leaves. The latter showed greater DPPH free radical scavenging capacity than the bark, although higher levels of SPF were obtained from the bark, with no statistically significant differences between methods. The results indicate that Erythrina velutina Willd. has potential as a photoprotector.
基金CAPES(Coordenacao de Aperfeicoamento de Pessoal de Nível Superior)for the master's scholarship(Proc.n.88887.822653/202300)CNPq(Conselho Nacional de Desenvolvimento Científico e Tecnológico-Brazil)for the PIBIC scholarship(Call 03/2023-UEPB/CNPq)+3 种基金CAPES(Coordenacco de Aperfeicoamento de Pessoal de Nível Superior)for the doctoral scholarship(Proc.n.88887.948069/202400)CAPES(Coordenacco de Aperfeicoamento de Pessoal de Nível Superior)for the doctoral scholarship(Proc.n.88887.995048/2024-00)CAPES(Coordenacco de Aperfeicoamento de Pessoal de Nível Superior)for the doctoral scholarship(Proc.n.88887.497186/202000)CNPq for the Research Productivity fellowship。
文摘Rocky outcrops function as island-like environmental filters and pivotal ecological refuges for local and regional biodiversity,with their inherent topographic and microclimatic dynamics directly shaping vegetation composition and distribution across slopes.This study inventoried the flora of a rocky outcrop slope within Brazil's Caatinga biome,a seasonally dry tropical forest,to analyze species distribution patterns and their relationship with microtopographic conditions.The slope was stratified into base,middle and top segments according to slope gradient,with specimens collected over seven months of field expeditions,followed by taxonomic processing to compile a floristic inventory.The survey documented 60 species,53 genera,and 28 families,with Fabaceae,Euphorbiaceae,and Malvaceae emerging as the most representative families;herbaceous species dominated,followed by trees and shrubs.Species richness declined along the topographic gradient as altitude increased,with 43%of flora comprising species widespread across Brazilian biomes and 20%endemic to the Caatinga.Variations in species distribution across slope positions suggest that topographic heterogeneity may drive distinct pedological and microclimatic conditions,directly influencing vegetation dynamics in rock outcrops.These findings underscore the role of microtopography in structuring plant communities in harsh environments.
基金To Federal University of Lavras,Foundation for the Support to the Researches in Minas Gerais(FAPEMIG),Brazilian National Council for Scientific and Technological Development(CNPq)and to Coordination for the Improvement of Higher Education Personnel(CAPES)for all the support.
文摘Our work aimed to test the hypothesis that soil microscale heterogeneity act as a community ecological driver,increasing diversity and promoting structural shifts on the Seasonally Dry Tropical Forest(SDTF)tree community.We evaluated the relationship between microscale edaphic variations and floristic–structural patterns of tree communities in a SDTF fragment located in the southern end of the Brazilian Caatinga domain.Vegetation and soil data were obtained through 27 sample units of 400 m2(20 m 920 m),within each one we measured and identified at species level all arboreal individuals with Circumference at the Breast Height greater or equal to 10 cm,and also collected the soil samples.Through the data we evaluated soil variation influence on the tree community structural and floristic patterns trough generalized linear models.Soil explained the small-scale structural and floristic variations,contributing significantly to biomass,sprouting and to floristic relationships between sample units.It was also observed a possible relation of the result with the Caatinga domain biogeographic history,due the presence of Sedimentary Caatinga species,which are not expected for the study region.Soil plays an important role in driving small-scale complexity and diversity of SDTF,but we also suggest that Caatinga biogeographic events have influence on the high heterogeneity patterns.
文摘Plant macronutrient distribution in podzolized sands of the Amazon caatinga has received attention in several studies;however, the distribution of micronutrients has not been assessed. Soil micronutrient availability has been hypothesized to reflect contrasting habitat characteristics as well as fundamental differences in substrate, and leaf micronutrient composition may reflect the macronutrient content needed to maintain balance for leaf cell functions. In this study, soil and leaf samples were obtained in a toposequence (valley, slope, and mound). Available soil micro- and macronutrients as well as total leaf content were measured by inductively coupled plasma-atomic emission spectrometer and mass spectroscopy. Soil Zn (-1) and B (-1) as well as Cu (-1) levels were very low. Soil Mn was low in the valleys and slopes (0.62-0.87 mg·kg-1), but higher in the mound (6.59 mg·kg-1). Soil Fe (11.48-21.13 mg·kg-1) was well above the critical level in all of the habitats. Leaf micronutrients Cu, B, Zn, and Fe were below the critical levels for tropical crops of 3-7, 20-70, 15-20, and 72 mg·kg-1, respectively. Leaf Mn (88 mg·kg-1) and Al (<50 mg·kg-1) were below the accumulators level. A strong relationship between leaf micro- and macronutrients suggests the maintenance of a homeostatic elemental composition, which may favour photosynthetic function. Therefore, the local distribution of species may be shaped by their abilities to maintain a balance of micronutrient collected through roots under critically low levels of available Zn, B, and Cu whilst excluding potentially deleterious ions of Mn, Fe, and Al.
基金funded in part by the Coordination for the Improvement of Higher Education Personnel,Brazil(CAPESFinance code 001)+1 种基金the Carlos Chagas Filho Foundation for Supporting Research in the State of Rio de Janeiro,FAPERJ.Tiago R TAVARES was funded by the São Paulo Research Foundation(FAPESP2020/16670-9).
文摘Soils(Leptosols or Epileptic Regosols)with lithic contact at a depth of 50 cm occupy almost 20%of the Brazilian semi-arid region.These lithic soils are susceptible to erosion due to faster saturation of water-holding capacity during rainfall,which accelerates the beginning of runoff.However,erosion traits of lithic soils in the semi-arid region of Brazil are less studied.The aim of this study was to characterize the soil and landscape attributes in areas with Neossolos Litólicos(Entisols)in the Caatinga biome to identify region of high susceptibility to erosion.Results showed that the soils were characterized by a sandy texture,soil structure with poor development and low content of organic carbon.These attributes increase susceptibility to erosion and reduce water storage capacity,especially in the states of Cearáand Sergipe.In these states,the content of rock fragments in the soil reaches 790 g/kg.High contents of silt and fine sand,high silt/clay ratio,predominance of Leptosols and strong rainfall erosivity were observed in Piauíand northwestern Ceará.A very high degree of water erosion was observed in the states of Pernambuco and Paraíba.Despite the low degree of erosion observed in the state of Bahia,it is highly susceptible to erosion due to the predominance of very shallow soils,rugged relief and high values of rainfall erosivity.Lower vulnerability was observed in the state of Alagoas because of its more smoothed relief,greater effective soil depth,thicker A horizon of soil and lower rainfall erosivity.In general,the characteristics that intensify the susceptibility to erosion in the Caatinga biome are those soil structures with poor development or without aggregation,low contents of organic carbon,high contents of silt and fine sand,high values of silt/clay ratio and rugged relief in some regions.This study collected information contributing to a better characterization of soils with lithic contact in the semi-arid region of Brazil.In addition,regions with a higher susceptibility to erosion were identified,revealing insights that could help develop strategies for environmental risk mitigation.
基金the National Council for Scientific and Technological Development-CNPq for granting financial support to the project(484260/2013-8).
文摘The volumetric variability of dry tropical forests in Brazil and the scarcity of studies on the subject show the need for the development of techniques that make it possible to obtain adequate and accurate wood volume estimates.In this study,we analyzed a database of thinning trees from a forest management plan in the Contendas de SincoráNational Forest,southwestern Bahia State,Brazil.The data set included a total of 300 trees with a trunk diameter ranging from 5 to 52 cm.Adjustments,validation and statistical selection of four volumetric models were performed.Due to the difference in height values for the same diameter and the low correlation between both variables,we do not suggest models which only use the diameter at breast height(DBH)variable as a predictor because they accommodate the largest estimation errors.In comparing the best single entry model(Hohenald-Krenn)with the Spurr model(best fit model),it is noted that the exclusion of height as a predictor causes the values of 136.44 and 0.93 for Akaike information criterion(AIC)and adjusted determination coefficient(R2 adj),which are poorer than the second best model(Schumacher-Hall).Regarding the minimum sample size,errors in estimation(root mean square error(RMSE)and bias)of the best model decrease as the sample size increases,especially when a larger number of trees with DBH≥15.0 cm are randomly sampled.Stratified sampling by diameter class produces smaller volume prediction errors than random sampling,especially when considering all trees.In summary,the Spurr and Schumacher-Hall models perform better.These models suggest that the total variance explained in the estimates is not less than 95%,producing reliable forecasts of the total volume with shell.Our estimates indicate that the bias around the average is not greater than 7%.Our results support the decision to use regression methods to build models and estimate their parameters,seeking stratification strategies in diameter classes for the sample trees.Volume estimates with valid confidence intervals can be obtained using the Spurr model for the studied dry forest.Stratified sampling of the data set for model adjustment and selection is necessary,since we find significant results with mean error square root values and bias of up to 70%of the total database.
文摘Management evaluation of Panicum maximum cv. massai (Massai guineagrass) under deferment contributes as a strategic reserve of forage in the Brazilian semi-arid region. The objective of this study was to evaluate biomass production and nutritive value of massai guineagrass in an area of thinned caatinga vegetation in two deferment periods (60 and 90 days after plot-leveling cut) and four use periods (30, 60, 90 and 120 days after the end of the rain season), in a random blocks design arranged in a split-plot (2 × 4), with three replications. Extending the deferment period of massai guineagrass promoted elevation of the biomass components, but compromised the pasture quality due to increasing stem biomass. The massai guineagrass deferred 30 days after raining season started and should use 90 days after raining season ended to ensure a forage supply of appropriate nutritional value. The increase in relative air humidity and the occurrence of rainfall after water restriction stimulate regrowth, resulting in improved nutritional value of the grass.
文摘The Caatinga biome is an important ecosystem in the semi-arid region of Brazil.It has significantly degraded due to human activities and is currently a region undergoing desertification.Thus,monitoring the variation in the Caatinga biome has become essential for its sustainable development.However,traditional methods for estimating aboveground biomass(AGB)are time-consuming and destructive.Remote sensing,such as optical and radar imaging,can estimate and correlate with vegetation.Nevertheless,radar imaging is still a novelty to be applied in estimating the AGB of this biome,which is an area with little research.Therefore,this study aimed to use Sentinel-1 images to estimate the AGB of the Caatinga biome in Sergipe State(northeastern Brazil)and to verify its influencing factors.Nineteen sample plots(30 m×30 m)were selected,and the stems of individuals with a circumference at breast height(1.3 m above the ground)equal to or greater than 6.0 cm were measured,and the AGB through an allometric equation was estimated.The Sentinel-1 images from 3 different periods(green,intermediate,and dry periods)were used to consider the phenological conditions of the Caatinga biome.All the pre-processing and extraction of attributes(co-polarized VV(vertical transmit and vertical receive),cross-polarized VH(vertical transmit and horizontal receive),and band ratio VH/VV backscatter,radar vegetation index,dual polarization synthetic aperture radar(SAR)vegetation index(DPSVI),entropy(H),and alpha angle(α))were performed with Sentinel’s Application Platform.These attributes were used to estimate the AGB through simple and multiple linear regressions and evaluated by the coefficients of determination(R2),correlation(r),and root mean squared error(RMSE).The results showed that the attributes individually had little ability to estimate the AGB of the Caatinga biome in the three periods.Combined with multiple regression,we found that the intermediate period presented the equation with the best results among the observed and estimated variables(R^(2)=0.73;r=0.85;RMSE=8.33 Mg/hm^(2)),followed by the greenness period(R2=0.72;r=0.85;RMSE=8.40 Mg/hm^(2)).The attributes contributing to these equations were VH/VV,DPSVI,H,α,and co-polarized VV for the green period and cross-polarized VH for the intermediate period.The study showed that the Sentinel-1 images could be used to estimate the AGB of the Caatinga biome in the green and intermediate phenological periods since the SAR attributes highly correlated with the estimated variable(i.e.,AGB)through multiple linear equations.
文摘The mixed forests of the upper Rio Negro at the northern of the Amazon basin grow in oxisol soils that are extremely infertile. These areas exhibit deficiencies in several macro-nutrients, and may also be characterized by the shortage or toxic excess of some micronutrients. The overall goal of this research is to collect more comprehensive information regarding the micronutrient composition of the upper Rio Negro forests as well as discern the relationship between leaf micro- and macro-nutrients that may contribute to the homeostasis and balance of the ionome. Firstly, the nutrient composition within the oxisol soil and leaf tissues of two top canopy tree species from the mixed forests was determined. We then analyzed the relationship between leaf micronutrient composition with N and P levels of the two species and that of species inhabiting the Amazon caatinga. Extractable soil Zn, B, Mn and Cu were very low in the mixed forest. In contrast, Fe and Al levels were potentially toxic. The analysis of leaf N/P ratios revealed for the first time the co-limitation of N and P in the mixed forest. This contrasts with species from the adjacent Amazon caatinga toposequence that are characterized by strong N limitation. All micronutrients within leaves of species inhabiting the mixed forest were also found to have low concentrations. Moreover, Fe and Al were detected at concentrations well below those reported for accumulator species. This suggested that leaf ion homeostasis was maintained under potentially toxic soil Fe and Al conditions. Leaf micronutrient (Fe, Zn and B) contents mirrored that of leaf N and P contents, and comparable Fe/N, Fe/P, Zn/N, Zn/P, B/N as well as B/P ratios were found across species and forest types. Therefore, forest species exhibited the capability to maintain leaf nutrient balances under soil conditions with deficient or toxic levels of micronutrients.
文摘This paper outlines procedures to analyze the desertification processes in the semi-arid Seridó Region (NE Brazil). Using the Geosystem theory, the detection of desertification areas was based on environmental indices, digital image processing in multispectral analysis and Geographic Information System (GIS).The first step was to treat the rainfall data and NDVI satellite Modis, aiming at identifying areas which do not present vegetation cover, even during the rainy seasons.The second step was to work on a regional scale using Landsat ETM + images (2000-2005) and data collected in the field, as the evaluations of exposed surfaces, that together with MDT/SRTM-NASA and thematic maps, allowed to classify the altitude and slope of the relief, soils type, different morphologies and geology, and correlate them with the areas susceptible to desertification process. The integration of the georeferenced data, related to these indicators, allowed the identification of five different levels of susceptibility to desertification (very high, high, moderate, low and very low), and the geographic domain of each class. Based on the analysis of the dynamics of the vegetation cover, we can establish that the main results refer that there is a decrease of the biomass at the region, associated with the dense caatinga vegetation areas, but more important, with the scrub and degraded areas.
基金This research was supported by the State of São Paulo Foundation(FAPESP)under project number 2012/12762-0.
文摘Species of the genus Erythrina are frequently used as ornamental plants and in projects to restore degraded areas. Also, extracts from its shoots and stems are popularly used as a herbal medicine with validated activity on the central nervous system. The objective of this study was to evaluate E. mulungu and E. velutina seed germination and seedling development potential aiming commercial scale production of those species. Seeds stored for one or twelve months at 10°C ± 2°C were sown in sand, soil or Plantmax? substrates and evaluated for germination and seedling development. Subsequently, seedlings sprouted in Plantmax? were transferred to polyethylene bags and kept in greenhouse, under direct sunlight for plant development (plant height, stem diameter and root length pivoting) evaluations. Four-month-old plantlets were transplanted to the field and after a period of one year the collar diameter and shoot height (of each plant were measured. Seed germination rates of both species grown in soil and in Plantmax? were significantly high (over 80%). Storing seeds for 1 month did not inhibit germination. However, seeds stored for twelve months had germination reduced by more than a quarter. The development of plants in greenhouse and in the field was satisfactory, indicating the viability of producing E. mulungu and E. velutina on a commercial scale, in order to meet the expanding market demand for herbal medicines.
文摘Introduction:Here,we compare the arbuscular mycorrhizal fungal(AMF)community composition in soils from the root zone of the exotic invasive species Prosopis juliflora(EXO soils)and soils from the root zone of the native species Mimosa tenuiflora(NAT soils)from five locations in the Brazilian tropical seasonal dry forest,Paraíba,Brazil,using morphological analyses.Results:AMF community composition in EXO and NAT soils were dissimilar.Available phosphorus,diversity index,spore abundance,and species richness were the main factors differing between the EXO and NAT soils.In general,the most dominant order present in the soils were Glomerales(44.8%)and Gigasporales(41.4%).The most abundant AMF genus in all studied soils was Funneliformis.Conclusions:Differences in AMF community composition were associated with(1)differences in the dominant plant species(P.juliflora vs.M.tenuiflora)and(2)changes in soil chemical factors(soil,pH,total organic carbon,total nitrogen,and available P)in EXO soils.These results contribute to a deeper view of the AMF communities in exotic soils and open new perspectives for ecological processes involving AMF species and exotic plant species in the Brazilian tropical seasonal dry forest.
文摘Aims Understanding succession in tropical forest is an important aspect of vegetation science,but to date,successional processes in sea-sonally dry tropical forests(SDtFs)have received much less atten-tion than evergreen humid tropical forests.We aim to fill this knowledge gap.Methods We investigated vegetation succession in SDtF areas consisting of three different successional stages(early,intermediate,late),and a SDtF-savanna ecotone in the municipal district of Juramento,north of Minas Gerais State,Brazil.Using twelve 400 m2 plots in each area,we compared vegetation parameters and structural variables(absolute density and basal area)and examined the floristic composition of the tree component to find gradients of change.Important Findings We found evidence of species turnover along a successional gradi-ent,with the intermediate stage showing the highest species rich-ness and diversity.this was accompanied with a significant increase in the number of tree individuals and basal area from the early to intermediate successional stage.However,the intermediate and late SDtF successional stages were more similar in structure and floristics.the ecotone was the most species rich and was similar to the intermediate SDtF and early successional stage in species richness and floristic composition respectively.these results will have implications for guiding SDtF management and recovery programs.
