Savanna

Este artigo avalia a eiciência dos métodos de parcelas de área ixa (PA) e pontos quadrantes (QD) na descrição de uma comunidade lenhosa de Cerrado Típico. Utilizamos 10 PA e 140 QD, distribuídos em cinco transeções. Comparamos a densidade de indivíduos, a composição lorística, a riqueza de famílias, gêneros e espécies e a estrutura vertical e horizontal da vegetação. O método de PA foi mais eiciente para amostrar densidade de indivíduos. O método de QD foi mais eiciente na caracterização da riqueza de espécies, da estrutura vertical da vegetação e do registro de espécies com baixa abundância. A composição de famílias, gêneros e espécies, bem como as espécies com maior índice de valor de importância na comunidade foram determinadas de maneira semelhante pelos dois métodos. Os métodos comparados são complementares. Sugerimos que o uso de PA, de QD ou de ambos os métodos pode ser direcionado ao parâmetro vegetacional investigado.

RESUMO: O trabalho consistiu na identificação de relictos da vegetação de Savana e Savanaestépica nas mesorregiões geográficas do Norte Central Paranaense e Norte Pioneiro Paranaense, nas bacias dos rios Tibagi, Laranjinhas e das Cinzas. O objetivo foi verificar se havia a presença de Savana e Savana-estépica e se estas encontradas nas áreas apresentavam-se fragmentadas, ou se formavam uma mancha contínua. Em algumas localidades, subsistem de forma esparsa, representadas por pequenos agrupamentos ou por plantas isoladas de espécies e gêneros próprios do Cerrado (Savana) brasileiro e da Savana-estépica, e sempre associados a afloramentos rochosos. Os pontos de coleta derivaram de um trabalho de esquadrinhamento, através de reconhecimentos de áreas no contexto da paisagem nas mesorregiões citadas, anotandose os pontos nos quais ocorriam espécies ou gêneros típicos das formações de Savana e Savana-estépica. Foram coletadas 34 espécies e/ou gêneros de Savana e Savana-estépica e destas, 11 foram encontradas no morro Três Irmãos em Terra Rica/PR, (mesorregião Noroeste); 9 puderam ser identificadas tanto em Campo Mourão (porção Centro Ocidental) como no Interflúvio Pirapó/Bandeirantes, 4 delas constam no levantamento realizado por Maack (1959/1968) e 16 não têm relação com nenhuma das áreas comparadas, porém todas elas estão relacionadas à vegetação de Savana e Savanaestépica do Brasil Central e Chaco. A altitude não foi um fator determinante na manutenção da Savana-estépica, pois estas foram localizadas desde a altitude de 246 até 724 metros. Já em relação às espécies de Savana, estas foram encontradas em altitudes que iam de 500 a 993 metros. As coletas foram feitas em 27 municípios, com a distribuição de 254 pontos onde se encontrou famílias, gêneros e/ou espécies de Savana e Savana-estépica. 244 destes, ou seja, 96,06% estão sobre o Grupo São Bento –Formação Serra Geral (basalto), os demais pontos, ou 3,94%, estão distribuídos sobre as Formações Santo Anastácio - Grupo Bauru (arenito) e Formação Palermo, nas quais a vegetação de Savana e Savana-estépica subsiste. O tipo de solo predominante nestas formações são principalmente os LVdf4 (Latossolo Vermelho Distroférrico), LVd9 (Latossolo Vermelho Distrófico), RLe5 (Neossolos Litólicos Eutróficos), RLe10 (Neossolos Litólicos Eutróficos) e, secundariamente, outros. O clima semiárido, em detrimento do atual semiúmido, que recobria grande parte do Brasil fez com que as espécies de Savana e Savana-estépica se fragmentassem através do processo de vicariância, já que estas ficaram restritas a inúmeras manchas com presença de Savana estépica persistindo sobre os afloramentos rochosos, e de Savana em solos extremamente ácidos do segundo Planalto, o que não impede que estas formações se estendam por corredores de aridez que seguiam pelos planaltos e topos durante as glaciações do Quaternário, na América do Sul, associados aos climas semiáridos e semiúmidos. Pode se considerar então que a expansão dessas espécies ou mesmo a retração ocorreram por influências climáticas, porém a sua persistência e distribuição se dá por influências pedológicas, que neste caso são os solos (Distróficos, Distroférricos) e os afloramentos rochosos.

ABSTRACT: This article consists on the identification of relicts of the savanna and the steppesavanna in the geographic mesoregions of Central North of Paraná and Pioneer North of Paraná, bowls in rivers the Tibagi, Laranjinhas and Cinzas. The aim was to verify the presence of savanna and the steppe-savanna and found in these areas presented fragmented or formed a continuous spot. In some places, it manages to survive in a sparse way, represented by small groupings or by isolated plants typical from the species and genera of the Brazilian cerrado (savanna) and steppe savanna, and always associated with outcrops. The selection of places for collecting the data were based on a scanning process of recognizing areas in the context of the landscape in the mentioned mesoregion, taking notes on the places where there were typical species or genera from the savanna and the steppe-savanna. 34 species or genera from the savanna or the steppe-savanna were collected and, among these, 11 can be found in the Três Irmãos (mesoregion in Northwest) hill in Terra Rica-PR; 9 can be identified both in Campo Mourão (Western portion Center) and in the inter-river region of Pirapó/Bandeirantes; 4 of them are present in the research from Maack (1959/1968); and 16 of them have no relation to any of the compared areas, although they are all related to the savanna and the steppe-savanna vegetation in Central Brazil and in the Chaco. The height was not a determinant factor in the maintenance of the steppe-savanna, as they were located in heights varying from 246 to 724 meters and the savana species were found in places where the height went from 500 to 993 meters. There were collecting places in 254 points distributed among 27 cities where there were savanna and/or steppe-savanna families, genera and/or species. Among these points, 244, or 96.6%, were on the São Bento Group – Serra Geral Formation (basalt), and the others, or 3.94% were distributed on the Santo Anastácio Formation – Bauru Group (sandstone) and on the Palermo Formation, where the savanna and the steppe-savanna vegetation subsists. The predominant kind of soil in these formations are mainly LVdf4(Dystroferric Red Latosol), LVd9 (Dystrophic Red Latosol), RLe5 (Eutrophic Litolic Neosol), RLe10 (Eutrophic Litolic Neosol) and others secundarily. The semi-arid climate, in place of the recent semi-umid one, that covered a great part of Brazil, caused the species of the savanna and the steppe-savanna to desintegrate through the vicariance process, as they were restricted to uncountable areas where there was the steppe-savanna persisting on the outcrops and the savanna on the extremely accid soil on the Second Plateau, which didn’t stop these formations to continue through corridors of drought that went over the plateaus and hills during the glacial times of the Quaternary in South America, associated to the semi-arid and semi-umid climates. Can then consider that the expansion of these species or even retraction occurred by climatic influences, but their persistence and distribution occurs by soil influences, which in this case are the soils (Dystrophic, dystroferric) and rocky outcrops

Aim: Parapatric distributional patterns can arise from abiotic or biotic factors, or from dispersal barriers. Climate change can potentially affect parapatry by changing species' potential geographic distribution, and thereby widening or shrinking contact zones. Here, we study the effects of climate change on all six species in the genus Callithrix, a group of small-sized Neotropical primates that is distributed parapatri-cally in eastern Brazil, allegedly due to biotic interactions. Location: Atlantic Forest, savanna and xeric shrublands from Brazil. Methods: We explore a method to investigate potential effects of climate change on the distribution of parapatric species by (a) determining whether the parapatric pattern is explained by abiotic (climate) or biotic (species' interactions) factors using niche equivalency and niche similarity tests; (b) estimating each species' potential distribution under current and future climatic conditions, using ecological niche models ; and (c) performing a pixel-by-pixel analysis in order to constrain distribution overlap between species pairs in which parapatry is maintained by biotic factors. Results: We found that parapatry in Callithrix is maintained mostly by abiotic factors, except for two species pairs (Callithrix aurita vs. C. flaviceps and C. geoffroyi vs. C. pen-icillata) in which biotic factors are more likely to be acting. Our proposed method is able to produce better models than conventional ecological niche modelling, predicting net reductions in distribution area for some species and increases for others; however, reductions generally exceeded expansions. The reduction in potential distribution areas would maintain Callithrix flaviceps as Endangered under IUCN criteria. Main conclusions: Despite range contractions and the loss of area of sympatry, climate change is unlikely to affect the parapatric distribution patterns in Callithrix, nor intensify interspecific interactions. K E Y W O R D S Atlantic forest, biotic interaction, contact zone, interspecific competition, niche overlap, primates

The vegetation and climate of the Pampa grassland, Argentina, during the late Quaternary are reconstructed from pollen recovered from dated stratigraphic sections from arroyo walls and from archaelogical excavations. Prior to 10,500 yr B.P., herbaceous psammophytic steppe existed in the central part of the Pampa grassland while xerophytic woodland associated with psammophytic and halophytic steppe occurred in the southwestern part of the Pampa. These types of vegetation and the continental conditions that prevailed in the area of the present-day coast (38°S), indicate subhumid-dry climate and annual precipitation 100 mm lower than present. A subsequent change toward a vegetation characteristic of ponds, swamps, and foodplains, or toward environments with locally more effective moisture, occurred ca. 10,500 yr B.P. suggesting annual precipitation close to modern levels or a higher availability of water in the central part of the Pampa grassland, this type of vegetation existed until 8000 yr B.P., when it was replaced by grassland communities that lasted until 7000 yr B.P. In the southwestern part of the Pampa grassland, this vegetation developed before 7000 yr B.P. and persisted until ca. 5000 yr B.P. Sea level higher than the present ca. 6200 yr B.P. is consistent with sharp modification of the vegetation and development of local halophytic communities dominant at 38°S. A return to subhumid-dry conditions occurred after 5000 yr B.P. The late Holocene vegetation is characterized by pollen assemblages similar to the psammophytic and halophytic communities of the Southern pampa grassland, associated with communities with more edaphic conditions. At the same time, at 38°S a sea level regression is suggested by the dominance of fresh-water pollen assemblages and micropaleontological remains. The trend toward humid, temperate conditions ca. 1000 yr B.P. suggested by vertebrate remains characteristic of temperate and humid conditions, as well as a very short but dry episode during the 18th century suggested by the geology, are not clearly evidenced in the pollen sequences. Vegetational and climatic changes are explained by the latitudinal shifts and changes in intensity of the southern atmospheric circulation and changes in sea level.

AimTo analyse spatial trade-offs in conservation of mammals, considering benefits of biodiversity conservation and socioeconomic costs.To analyse spatial trade-offs in conservation of mammals, considering benefits of biodiversity conservation and socioeconomic costs.LocationCerrado Biodiversity Hotspot, Brazil.Cerrado Biodiversity Hotspot, Brazil.MethodsWe built ecological niche models (ENMs) for 154 mammals inhabiting the cerrado. We combined model projections to produce consensus maps of species' distributions for three types of models (envelope, statistical and machine-learning models). We used these range summaries as input data in spatial prioritization analyses. We compared six conservation scenarios, considering human population density, land cost, anthropogenic land use, political willingness to act and the distribution of species using trade-off analyses. We complemented the current network of protected areas, aiming to achieve a target of 17% of land protection in the cerrado.We built ecological niche models (ENMs) for 154 mammals inhabiting the cerrado. We combined model projections to produce consensus maps of species' distributions for three types of models (envelope, statistical and machine-learning models). We used these range summaries as input data in spatial prioritization analyses. We compared six conservation scenarios, considering human population density, land cost, anthropogenic land use, political willingness to act and the distribution of species using trade-off analyses. We complemented the current network of protected areas, aiming to achieve a target of 17% of land protection in the cerrado.ResultsSpecies-rich sites coincide with regions with high human population, high land cost, high anthropogenic land use and diverse levels of political willingness to act. We found a significant change in spatial priorities when we included socioeconomic and political dimensions in analyses: top-priority sites moved north, reduced by 68% potential conservation conflicts with human population, reduced by 72% the total monetary cost of actions and reduced by 68% conflict with other anthropogenic land uses. It also increased by 80% the beneficial effect of political willingness to act.Species-rich sites coincide with regions with high human population, high land cost, high anthropogenic land use and diverse levels of political willingness to act. We found a significant change in spatial priorities when we included socioeconomic and political dimensions in analyses: top-priority sites moved north, reduced by 68% potential conservation conflicts with human population, reduced by 72% the total monetary cost of actions and reduced by 68% conflict with other anthropogenic land uses. It also increased by 80% the beneficial effect of political willingness to act.Main conclusionsOur results reinforce the idea that using only biological criteria for proposing spatial conservation priorities can undermine conservation plans given increases in socioeconomic and political conflicts.Our results reinforce the idea that using only biological criteria for proposing spatial conservation priorities can undermine conservation plans given increases in socioeconomic and political conflicts.

The mechanisms permitting the co-existence of tree and grass in savannas have been a source of contention for many years. The two main classes of explanations involve either competition for resources, or differential sensitivity to disturbances. Published models focus principally on one or the other of these mechanisms. Here we introduce a simple ecohydrologic model of savanna vegetation involving both competition for water, and differential sensitivity of trees and grasses to fire disturbances. We show how the co-existence of trees and grasses in savannas can be simultaneously controlled by rainfall and fire, and how the relative importance of the two factors distinguishes between dry and moist savannas. The stability map allows to predict the changes in vegetation structure along gradients of rainfall and fire disturbances realistically, and to clarify the distinction between climate- and disturbance-dependent ecosystems.

African Savannahs have substantial land resources that could be used for the production of food and fiber and a major source for the prosperity for the countries where they are located.  This document studied the case of Angola’s Savannahs and proposes a framework to promote the sustainable development of the country so as to take full advantage of its Savannahs’ potential.

Geochemical and palynological analyses of core CR1 from Crominia, Goi~is, provided information on the paleoenvironmental history of central Brazil. The records show that prior to 32,400 yr B.P. the vegetation of the Crominia region was similar to the present one characterized locally by a complex of cerrado, gallery forest and palm swamp, indicating a semi-humid tropical climate. A palm swamp occupied the coring site. From 32,400 to about 20,000 yr B.P. a treeless grassland replaced the arboreal cerrado and the gallery forest suggesting that humidity increased but temperature probably decreased. The site was a shallow lake between ca. 27,000 and 20,000 yr B.P. Humidity started to decrease at ca. 18,500 yr B.P. and the period from ca. 18,500 to ca. 11,500 yr B.P. was very dry. A sparse vegetation was growing in the region during that time. The dry climate continued until 6500 yr B.P. and the core site probably dried out several times. At ca. 5000 yr B.P. humidity increased again, the palm swamp vegetation returned to the site and cerrado vegetation and gallery forest started to grow in the region. The abundant charcoal particles prior to 20,000 yr B.P. and from 10,500 to ca. 3500 yr B.P. document a long history of fires in the region. Results are compared with those from other sites in Central Brazil and with the climate sequence of the last glacial maximum and postglacial time in the tropical Andes.

1 Embrapa Rondônia, c. postal 406 -Porto Velho/RO, 78900-970 [email protected]; 2 Embrapa Hortaliças, c. postal 218, Brasília/DF, 70359-970 [email protected]; 3 Faculdade São Lucas -Porto Velho/RO [email protected] RESUMO O objetivo deste ensaio foi avaliar a incidência de queima-das-folhas e a qualidade das raízes de genótipos de cenoura em cultivo na região de cerrado pré-Amazônico, durante o período do ano com as maiores precipitações pluviométricas. O ensaio foi conduzido no Campo Experimental da Embrapa Rondônia no município de Vilhena/RO. O delineamento experimental utilizado foi o de blocos ao acaso, com 11 tratamentos (genótipos: Brazlândia, Alvorada, Carandaí, Brasília Bionatur, Brasília Hortec, Brasília selecionada Agroflora,

In this study, we describe and illustrate Piriqueta crenata, a new species from the Chapada Diamantina region, Bahia, Brazil. It is similar to and was initially identified as P. flammea from which it can be distinguished by the cuneate leaf blade bases (vs. rounded), slightly discoloured leaves (vs. strongly discoloured), inflorescences of fewer flowers (1-3 vs. 3-6), olive-green calyx when dry (vs. blackened), and yellow corolla (vs. orange red). Piriqueta crenata is only known from a single small savanna nested in the semiarid Chapada Diamantina region, close to areas under anthropogenic influence. Therefore, we evaluate the species as Critically Endangered.

Distribution and abundance of tree species of savanna woodland in Pantanal wetlands, Mato Grosso do Sul State, Brazil). The woodland savannas occupy non-flooding areas in the Pantanal wetlands and are an important resource for regional economy. Even though, wood from woodland savannas are cut and used for fences, pens, and sheds in the farm, there are not much information from woodland savannas regarding sustainable uses and conservation. This study investigated the abundance, the distribution of species and correlations with soil fertility in six areas of woodland savanna ("cerradão") in Southern Pantanal wetlands. The survey was accomplished by means of 30 point-centred quarters in each area, totalling 120 trees sampled with the circumference at breast height (CBH) ≥ 15 cm. The association between floristic composition, abundance of species and soil fertility were determined by the principal components analysis (PCA). Savanna forests are very heterogeneous, presenting different levels of soil fertility as well as vegetation structure and composition. Two of them were clustered according to soil fertility and vegetation structure, they both presented large stands of the tree Qualea grandiflora Mart., species that seems to prefer soil with larger phosphorous quantity. Two other areas of savanna forests showed similar floristic composition, despite being in areas where the soil presented different levels of fertility, pointing out the human disturbance.

As a fundamental element of human lives, ecosystems and the services they provide across all socioecological regions are now under threat from human and natural activities. An assessment of the different categories of ecosystem services at various levels has become necessary for sustainable use and conservation. This study seeks to identify and characterize provisioning ecosystem services affecting rural households in the Tolon and Wa West Districts of northern Ghana. It examines the key dynamics of these services and discusses the major factors influencing their supply and utilization. The study employs rapid rural appraisal methods, including key informant interviews, household questionnaires surveys, focus group discussions, and participatory observations for collecting primary data. Findings indicate an extensive use of all provisioning services examined: bushmeat, crop and animal production, fish catches, fodder and forage, fuelwood, building materials, fresh water, and wild pl...

As a fundamental element of human lives, ecosystems and the services they provide across all socioecological regions are now under threat from human and natural activities. An assessment of the different categories of ecosystem services at various levels has become necessary for sustainable use and conservation. This study seeks to identify and characterize provisioning ecosystem services affecting rural households in the Tolon and Wa West Districts of northern Ghana. It examines the key dynamics of these services and discusses the major factors influencing their supply and utilization. The study employs rapid rural appraisal methods, including key informant interviews, household questionnaires surveys, focus group discussions, and participatory observations for collecting primary data. Findings indicate an extensive use of all provisioning services examined: bushmeat, crop and animal production, fish catches, fodder and forage, fuelwood, building materials, fresh water, and wild plants by households at all study sites. Averagely, 80% of households across the study sites collect and utilize these variety of services to support livelihood strategies. Our study also identified major challenges for sustainable supply and use of these ecosystem services, including the growing scarcity and decline in these services attributed to closely connected drivers such as cyclical drought, climate variation, land conversion, overharvesting, and a decline in traditional ecological knowledge. This study thus demonstrates the need for an integrated assessment that examines, at the local level, the interactions of various ecosystem services and human well-being to provide a scientific basis for formulation of effective coping and adaptation strategies in the midst of these challenges

Drought can affect forest structure and function at various spatial and temporal scales. Forest response and recovery from drought may be a result of position within landscape. Longleaf pine forests in the United States have been observed to reduce their carbon sequestration capacity during drought. We collected eddy covariance data at the ends of an edaphic longleaf pine gradient (xeric and mesic sites) over seven years; two years of normal rainfall were followed by 2.5 years of drought, then 2.5 years of normal or slightly above-average rainfall. Drought played a significant role in reducing the physiological capacity of the sites and was compounded when prescribed fire occurred during the same periods. The mesic site has a 40% greater basal area then the xeric site, which accounts for its larger sequestration capacity; however, both sites show the same range of variance in fluxes over the course of the study. Following drought, both sites became carbon sinks. However, the xeric s...

Aim This study aims to improve the formulation and results of the Brazilian Center for Weather Forecasting and Climate Studies Potential Vegetation Model (CPTEC-PVM) by developing a new parameterization for the long-term occurrence of fire in regions of potential savannas in the tropics. Compared with the relatively slow processes of carbon uptake and growth in vegetation, fast mortality and biomass consumption by fires may favour grasses and reduce tree coverage. Location The tropics. Methods For finding large-scale relationships between fires and other environmental factors, we made two main simplifying assumptions. First, lightning is the most important source of ignition for natural fires. Second, over continental areas in the tropics, lightning is mainly related to the zonal flux of moisture transport. Results The parameterization of fire occurrence was built based on a simple empirical relationship, combining information on mean and intra-annual variance of the zonal wind. Main conclusions The implementation of this new relationship improved the formulation and the results of the CPTEC-PVM. As a result of this new parameter, the accuracy of the model in allocating the correct vegetation (seasonal forests) instead of savannas for large regions in India and Southeast Asia is now substantially higher than in previous studies.

Neste estudo objetivou-se avaliar o manejo para a espécie Stryphondendron adstringens a partir
de diferentes intensidades de cortes seletivos com controle por classe de diâmetro no norte de
Minas Gerais. A produção estimada para elaboração dos planos foi obtida a partir de equações
para peso seco de casca e volume de madeira para uma área de 31,28 ha e considerando uma
demanda comercial de 7.000 kg. ano–1 de cascas. De posse da produção foram simulados dez planos
de manejo pelo método GDq. Os planos foram compostos pela remoção de percentuais de área
basal (G), em múltiplos de dez a partir de 10% de remoção de G, até o corte raso, totalizando dez
planos. Os resultados obtidos mostraram que a colheita sustentável deve ser realizada dentro do
intervalo de 40 a 70% de remoção de G, que apresentaram respectivamente as seguintes produções
de cascas e volume: 224,00 kg-ha–1 e 367,16 kg-ha–1; 0,63 m3-ha–1 e 1,06 m3-ha–1. Conclui-se que
o manejo sustentável do barbatimão no norte de Minas Gerais é viável dentro dos intervalos de
remoção de 40 a 70% de área basal a partir do controle da colheita pelo método GDq.

The study examines the extent of poverty and its determinants among farming households in Borno State of Nigeria. Primary data were obtained from 1,998 farming households using well-structured questionnaires in 2004. Mean monthly per adult equivalent household expenditure poverty line was used to characterize the households into poor and non-poor, while Tobit regression model was used to determine the factors associated with poverty experienced by the farming households in the study area. About 67% of the households were categorized as poor. The Tobit regression analysis reveals that 15 out of the 23 household livelihood-related variables included in the model had their coefficients significant at between (P<0.01) and (P<0.10), representing about 63 percent of the variables. The Tobit result reveals that increases in farm size, amount of credit, agricultural production diversification and extent of agricultural output commercialization contributed to reduce the poverty level a...

Contrary to floral nectaries that attract and reward vertebrate and invertebrate pollinators, EFNs are especially attractive to ants and a variety of other nectar-foraging insects such as wasps, bees, flies and beetles, and more rarely spiders and mites (e.g.

The paper analyzes farmers' perceptions, profitability, and factors influencing the adoption of improved maize varieties (IMV) in the Guinea savannas of Borno State, Nigeria. A multistage sampling design was used to select 232 households. Respondents were interviewed using a structured questionnaire. Descriptive statistics, budgetary techniques, and Tobit Model were used as analytical tools. Results show that early maturity and high grain yields of IMV positively increased adoption by 66.4% among farmers. The gross margin results indicated that IMV was highly profitable with a mean gross margin of N65,289 (Є384)/ha as against local varieties with a mean gross margin of 34,691 (Є204)/ ha. The Tobit result shows that statistically (ρ = 0.05) factors that influenced the adoption of IMV (with expected signs) included farm size, extension contact, access to credit, fertilizer, farming experience, and household size. Policies that enhanced farmers' access to credit facilitated a...

In 1954 was established National Park Niokolo-Koba. After gaining independence and emerging from the state of Senegal the National Park was extended due to the biodiversity and wildlife protection. From this reason, in 1969 local villages had been relocated beyond area of the extended park. Villages have been linked to ecosystem of the tree savanna for centuries and they have been constituted as living functional unit. Trees in villages are not only the source of the necessary raw materials for local residents. They provide important role for their livelihoods and appropriate shelter from the sun. But their importance is also deeply connected with the healing and animistic tradition. In this beginning project, we study the relations between trees and villages with long-term continuity of settlement, but also with the newly relocated villages after constitution of the park. We identify which tree species are most common in abandoned villages and which can be an identifier of an aband...

RESUMO Neste estudo objetivou-se avaliar o manejo para a espécie Stryphondendron adstringens a partir de diferentes intensidades de cortes seletivos com controle por classe de diâmetro no norte de Minas Gerais. A produção estimada para elaboração dos planos foi obtida a partir de equações para peso seco de casca e volume de madeira para uma área de 31,28 ha e considerando uma demanda comercial de 7.000 kg. ano–1 de cascas. De posse da produção foram simulados dez planos de manejo pelo método GDq. Os planos foram compostos pela remoção de percentuais de área basal (G), em múltiplos de dez a partir de 10% de remoção de G, até o corte raso, totalizando dez planos. Os resultados obtidos mostraram que a colheita sustentável deve ser realizada dentro do intervalo de 40 a 70% de remoção de G, que apresentaram respectivamente as seguintes produções de cascas e volume: 224,00 kg-ha–1 e 367,16 kg-ha–1; 0,63 m3-ha–1 e 1,06 m3-ha–1. Conclui-se que o manejo sustentável do barbatimão no norte de ...

Whereas leaf gas exchange properties are important to assess carbon and water fluxes in ecosystems worldwide, information of this type is scarce for savanna species. In this study, gas exchange characteristics of 2 C4 grass species Andropogon canaliculatus and Hyparrhenia diplandra and 2 C3 tree species Crossopteryx febrifuga and Cussonia arborea from the West-African savanna of Lamto Ivory Coast were investigated in the field. Measurements were done in order to provide data to allow the parameterization of biochemically-based models of photosynthesis for C4 and C3 plant metabolic types and stomatal conductance ; and to compare gas exchange characteristics of coexisting species. No systematic difference was found between grass and tree species for reference stomatal conductance, under standard environmental conditions, or stomatal response to incident light or vapour pressure deficit at leaf surface. Conversely, grass species displayed higher water 1.5-2 fold and nitrogen 2-5 fold photosynthetic use efficiencies WUE and NUE, ratio of net photosynthesis to transpiration and leaf nitrogen, respectively. These contrasts were attributed to the CO2 concentrating mechanism of C4 plants. When looking within plant life forms, no important difference was found between grass species. However, significant contrasts were found between tree species, Cussonia showing higher NUE and reference stomatal conductance than Crossopteryx. These results stress the need to account for functional diversity when estimating ecosystem carbon and water fluxes. In particular, our results suggest that the tree/grass ratio, and also the composition of the tree layer, could strongly affect WUE and NUE at the ecosystem scale in West African savannas.

Accurate differentiation between tropical forest and savannah ecosystems in the fossil pollen record is hampered by the combination of: i) poor taxonomic resolution in pollen identification, and ii) the high species diversity of many lowland tropical families, i.e. with many different growth forms living in numerous environmental settings. These barriers to interpreting the fossil record hinder our understanding of the past distributions of different Neotropical ecosystems and consequently cloud our knowledge of past climatic, biodiversity and carbon storage patterns. Modern pollen studies facilitate an improved understanding of how ecosystems are represented by the pollen their plants produce and therefore aid interpretation of fossil pollen records. To understand how to differentiate ecosystems palynologically, it is essential that a consistent sampling method is used across ecosystems. However, to date, modern pollen studies from tropical South America have employed a variety of methodologies (e.g. pollen traps, moss polsters, soil samples). In this paper, we present the first modern pollen study from the Neotropics to examine the modern pollen rain from moist evergreen tropical forest (METF), semi-deciduous dry tropical forest (SDTF) and wooded savannah (cerradão) using a consistent sampling methodology (pollen traps). Pollen rain was sampled annually in September for the years 1999-2001 from within permanent vegetation study plots in, or near, the Noel Kempff Mercado National Park (NKMNP), Bolivia. Comparison of the modern pollen rain within these plots with detailed floristic inventories allowed estimates of the relative pollen productivity and dispersal for individual taxa to be made (% pollen / % vegetation or ‘p/v’). The applicability of these data to interpreting fossil records from lake sediments was then explored by comparison with pollen assemblages obtained from five lake surface samples.
Pollen productivity is demonstrated to vary inter-annually and conforms to a consistent hierarchy for any given year: METF > SDTF > cerradão. This suggests an association between pollen productivity and basic structural characteristics of the ecosystem, i.e. closed canopy vs. open canopy vs. savannah. Comparison of modern pollen and vegetation revealed that some important floristic elements were completely absent from the pollen: Qualea and Erisma (METF), Bauhinia, Simira and Guazuma (SDTF), and Pouteria and Caryocar (cerradão). Anadenanthera was found to be abundant in both the pollen and flora of SDTF (p/v = 3.6), while Poaceae was relatively poorly represented in cerradão (0.2). Moraceae, Cecropia and Schefflera were found to be over-represented palynologically in all ecosystems. Overall, the data demonstrated that no one taxon could be used as a definitive indicator of any of the ecosystems. Instead, associations of taxa were found to be important: METF = Moraceae (>40%), Cecropia, Hyeronima, Celtis; SDTF = Anadenanthera, Apuleia, Ferdinandusa and non-arboreal Asteraceae, Bromeliaceae, Piper and fern spores; cerradão = Poaceae, Myrtaceae, Borreria, Solanum plus Asteraceae and fern spores. Interpretation of Poaceae pollen was highlighted as problematic, with relatively low abundance in the cerradão (<20%) in comparison to high abundance in lake environments (c. 30-50%). Re-examination of fossil pollen records from NKMNP revealed that modern vegetation associations were only established in the last few thousand years.

Projected increases in Africa's human population over the next 40 years point to further, large-scale conversion of natural habitats into farmland, with far-reaching consequences for raptor species, some of which are now largely restricted to protected areas (PAs). To assess the importance of PAs for raptors in Uganda, we conducted an annual road survey through savanna, pastoral and agricultural land during 2008-2015. Here, we present density estimates for 34 diurnal raptor species, 17 of which were encountered largely or entirely within PAs. These included seven out of eight globally threatened or near-threatened species surveyed. Based mainly on published demographic values, we converted density estimates (birds 100 km-2) to numbers of adult pairs, for 10 resident, savanna-dependent species. We then estimated adult population sizes within conservation areas (individual PAs and clusters of contiguous PAs), based on the area of savanna in each site. This suggested that two threatened residents, Martial Eagle Polemaetus bellicosus and Lappet-faced Vulture Torgos tracheliotos, have national breeding populations of just 53-75 and 74-105 pairs, respectively. A third species, Whiteheaded Vulture Trigonoceps occipitalis, may have a breeding population of just 22-32 pairs. In each case, at least 90% of pairs are thought to reside within Uganda's five largest conservation areas. In three cases our estimates of pair density were markedly lower than in other studies, while in six cases they were broadly consistent with published findings, often derived using more intensive survey methods. Further work is required to determine the accuracy of our estimates for individual conservation areas, and to assess the long-term viability of Uganda's threatened raptor populations.

Introduction: Recent studies at sites in northern Australia have reported severe and rapid decline of several native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security. All of the more speciose taxonomic groups of mammals in northern Australia have some species for which their conservation status has been assessed as threatened, with 53 % of dasyurid, 47 % of macropod and potoroid, 33 % of bandicoot and bilby, 33 % of possum, 30 % of rodent, and 24 % of bat species being assessed as extinct, threatened or near threatened. However, the geographical extent and timing of declines, and their causes, remain poorly resolved, limiting the application of remedial management actions. Material and methods: Focusing on the tropical savannas of northern Australia, this paper reviews disparate recent and ongoing studies that provide information on population trends across a broader geographic scope than the previously reported sites, and examines the conservation status and trends for mammal groups (bats, macropods) not well sampled in previous monitoring studies. It describes some diverse approaches of studies seeking to document conservation status and trends, and of the factors that may be contributing to observed patterns of decline.

The hypothesis that application of starter nitrogen (N) fertilizer to cowpea may increase grain and fodder yields and profitability was tested in the Guinea and Sudan savanna zones of northern Ghana. Two cowpea varieties (Apagbaala: grain-type and Padi-Tuya: dual purpose) and three N fertilizer rates (0-30-30, 15-30-30 and 30-30-30 N-P2O5-K2O kg/ha) were evaluated using a 2 × 3 factorial treatments arrangement in a randomized complete block design with three replicates. Grain and fodder yields, 100 seed weight (SW) and net return of Padi-Tuya increased significantly compared with Apagbaala in both zones. Application of starter N fertilizer increased grain yield, fodder yield, N use efficiency (NUE) and net return by more than 30% compared with the control in both zones. Padi-Tuya cowpea with 15 kg/ha N fertilizer was risk efficient at all risk aversion levels when only grain was considered, but Padi-Tuya with 30 kg/ha N fertilizer becomes the most risk efficient option when the valu...

Historically, pine savannas characterized landscapes across the Gulf Coastal Region, including most of Florida. Treeless habitats (historically called "prairies") also occurred as lowland inclusions in savanna landscapes. What restricted trees from prairies? We develop a conceptual model that is based on prior models of prairie-forest landscapes. We use predicted relationships between trees and graminoids to explore how fire and seasonal flooding might influence the continuum from closed-canopy forests to open-canopied savannas to treeless prairies. The starting model predicts community position along this continuum as a function of fire frequency. We then modify this conceptual model to include evolutionary adaptations of trees that result in survival of frequent, low-intensity fires. Finally, we modify it to incorporate postulated interactive effects of fire and seasonal flooding on trees and graminoids. This model may be useful in predicting characteristics of savanna-prairie mosaics in the southeastern United States. We apply this model to the dry prairie landscape of central Florida. We examine two regions with pine flatwoods and dry prairies: Myakka River State Park (Sarasota and Manatee Counties) close to the Gulf coast and Avon Park Air Force Range (Polk and Highlands Counties) in the interior of the peninsula. For these two regions we compare local climatic conditions predicted to facilitate the occurrence of pine flatwoods and dry prairie. Specifically, we compare the conditions likely to result in lightning fires in the two regions and compare those with the likelihood of post-fire flooding in pine flatwoods and dry prairies in each of the two regions. These climatic patterns indicate a close temporal association of fires and flooding during the summer growing season at both sites. The increase in frequency of lightning strikes in April-June occurs at the same time that the mean rain-free interval reaches a maximum and the mean ground water levels reach a minimum. Thus, large fires in the landscape are expected at this time. Within a few weeks the frequency of thunderstorms increases, resulting in frequent rains. Rapid increases in mean water levels saturate the soil. Consequently, early lightning season fires are followed soon by flooding. Thus, environmental conditions predicted not to favor trees occur seasonally in dry prairie landscapes. We anticipate that subtle differences in the likelihood of surface soil saturation will influence survival of trees, resulting in prairie inclusions in the pine flatwoods landscapes of central Florida.

Background: No studies have examined the invasion of exotic species used for forestry purposes in the savannas of the Brazilian Amazonia. Aims: We investigated the invasion process of Acacia mangium in savanna areas adjacent to large-scale forestry plantations in northeastern Roraima State, Brazilian Amazonia. Methods: A tree inventory to record the presence of all A. mangium and native tree individuals was carried out in of 14 plots (each 50 m in width and 1500 m in length) established at five plantation sites. Biometric measurements were taken for all individuals to identify their structure and maturity. Distance categories were created for determining frequency of occurrence in 100 m sections along the plots for all individuals. Correlations and goodness-of-fit tests for discrete data ordered in categories were applied to verify the occurrence of A. mangium plants in relation to distance from the plantation. Results: Individuals of A. mangium were dispersed up to 900 m from the plantation edge 8-9 years after the plantation was established. Although most recorded individuals were in the juvenile stage, reproductive adults were found in two establishment patterns: non-nucleated and nucleated under native tree species. Crown cover of the savanna's most abundant native tree species facilitated the regeneration of A. mangium. Conclusions: Planting of A. mangium in Amazonian savannas provides a source of continuous dispersal, and invasion by the species is facilitated by environmental conditions.

Historically, pine savannas characterized landscapes across the Gulf Coastal Region, including most of Florida. Treeless habitats (historically called "prairies") also occurred as lowland inclusions in savanna landscapes. What restricted trees from prairies? We develop a conceptual model that is based on prior models of prairie-forest landscapes. We use predicted relationships between trees and graminoids to explore how fire and seasonal flooding might influence the continuum from closed-canopy forests to open-canopied savannas to treeless prairies. The starting model predicts community position along this continuum as a function of fire frequency. We then modify this conceptual model to include evolutionary adaptations of trees that result in survival of frequent, low-intensity fires. Finally, we modify it to incorporate postulated interactive effects of fire and seasonal flooding on trees and graminoids. This model may be useful in predicting characteristics of savanna-prairie mosaics in the southeastern United States. We apply this model to the dry prairie landscape of central Florida. We examine two regions with pine flatwoods and dry prairies: Myakka River State Park (Sarasota and Manatee Counties) close to the Gulf coast and Avon Park Air Force Range (Polk and Highlands Counties) in the interior of the peninsula. For these two regions we compare local climatic conditions predicted to facilitate the occurrence of pine flatwoods and dry prairie. Specifically, we compare the conditions likely to result in lightning fires in the two regions and compare those with the likelihood of post-fire flooding in pine flatwoods and dry prairies in each of the two regions. These climatic patterns indicate a close temporal association of fires and flooding during the summer growing season at both sites. The increase in frequency of lightning strikes in April-June occurs at the same time that the mean rain-free interval reaches a maximum and the mean ground water levels reach a minimum. Thus, large fires in the landscape are expected at this time. Within a few weeks the frequency of thunderstorms increases, resulting in frequent rains. Rapid increases in mean water levels saturate the soil. Consequently, early lightning season fires are followed soon by flooding. Thus, environmental conditions predicted not to favor trees occur seasonally in dry prairie landscapes. We anticipate that subtle differences in the likelihood of surface soil saturation will influence survival of trees, resulting in prairie inclusions in the pine flatwoods landscapes of central Florida.