weather, soils and vegetation coverage. Throughout the length of the country there are portions with similar characteristics and continuous biodiversity, which defines the so-called “biomes”. A biome is understood as a set of all living beings in a region that presents uniformity and a common history in its formation. There are six well- defined biomes in Brazil (% in area): Amazon (49,29%), Cerrado (23,92%), Atlantic Forest (13,04%), Caatinga (9,92%), Pampa (2,07%) and Pantanal (1,76%) (IBGE, 2016). The Caatinga is an exclusively Brazilian biome. Etymologically, the term Caatinga (Tupi-Guarani) means white forest. This name stems from the whitened landscape, characterized by the appearance of the tree trunks in the dry season due to the almost total loss of foliage. Nearly 10% of the national territory, occupied by the Caatinga, encompasses part of the states of Alagoas, Bahia, Ceará, Maranhão, Minas Gerais, Paraíba, Pernambuco, Piauí, Rio Grande do Norte and Sergipe.
The vegetation structure can be used as an indicator of an ecosystem’s conservation state. Thus, a forest inventory with multiple measurements of floristic and structural parameters is often the only way of predicting the components of vegetation changes over time (Batista et al., 2015; Rodrigues et al., 2016). The type of vegetation in ecosystems influences the redistribution of local water resources. Therefore, interception loss is an important hydrological agent (Zhang et al., 2015). The factors controlling the distribution of rain water upon interaction with plant canopies are numerous and complex, and they vary across species, land use, meteorological conditions, precipitation characteristics (Ávila et al., 2014; Siegert et al., 2016). Moreover, physiological and morphological characteristics related to forest composition and leaf canopy seasonality control rainfall partitioning (Siegert et al., 2016). The aim was to investigate the floristic composition and phytosociological structure in an anthropized Caatinga area in the State of Pernambuco, Brazil, and to identify which structural variables affect the rainfall partitioning. This information expands the database on anthropized Caatinga fragments.
A basic implication of our results regards setting prioritie areas for conservation of caatinga biodiversity. The caatinga’s system of protected natural areas covers 0.87% of the caatinga region (Tabarelli et al., 2000). In addition, current economic activities are projected to eliminate or seriously degrade large portions of this ecosystem (Coimbra-Filho & Câmara, 1997). Large efforts by the national government and research institutions have thus been conducted to identify priority areas for conserving caatinga biodiversity (Silva & Tabarelli, 2000). This is a difficult task since caatinga is poorly known scientifically (see Heyer, 1988; Brasil, 1998). The best approaches for setting priority areas still remain dependent on species distribution databases (Margules & Pressey, 2000), which are incomplete or absent for caatingaspecies. A logical prediction from our results is that the large between-roads patches contain the last low- altered portions of this ecosystem, once roads and cities are related to habitat loss and fragmentation. A regional plan for setting priority areas for conservation of caatinga should thus consider road and city density as a predictor of previously disturbed areas and as potential sources of habitat degradation regarding future protected areas.
The global impact of deforestation driven largely by agricultural expansion is a major component of ongoing global environmental change that contributes significantly to atmospheric greenhouse gas accumulation and climate change (ZOMER et al., 2008), which, in turn, will contribute for the decrease of fresh water available and thus an aridization of the environment (MARENGO, 2014; SALAZAR; NOBRE; OYAMA, 2007). Unfortunately, the amount of land affected by salinity alone or combined with other stresses and the amount of brackish groundwater in semiarid areas is expected to increase in the near future according to the estimations for the global climate change (IPCC, 2013). At the same time, almost 500.000 ha of Caatingavegetation are deforested per year and are predicted to decrease by aridization (SALAZAR; NOBRE; OYAMA, 2007). The scarcity of rainfall and the lack of a development policy that takes into account regional specificities compromises the quality of life in the Caatinga domain. In this context, it is necessary to preserve the best quality freshwater for human supply, as well as to seek the use of marginal waters, such as brackish waters or domestic sewage treated for irrigation. Since fresh drinking water demands are intensifying due to world population growth, wastewater and brackish water are being considered a valuable resource in agriculture. Thus, problems related to water shortages have increased interest in research related to safe and controlled wastewater application techniques (HAMILTON et al., 2007).
The most obvious role of epicuticular waxes is the restriction of water loss by transpiration. In caatinga habitats, apparently epicuticular waxes alone do not suffice to warrant survival along the most severe pe- riods of drought. Leaf shading is almost always the rule among caatinga plants, the leaves thus escaping the harshest pressures of hydric shortage. Z. joazeiro is an exception, being a woody species that only rarely loses its leaves. Survival of Z. joazeiro is guar- anteed by an efficient stomatal mechanism, com- bined with extensive root systems capable of taking up moisture from deep layers under the soil surface (Ferri 1955, Andrade-Lima 1981, Sampaio 1995). Results of the present work suggest that an addi- tional factor of drought resistance of Z. joazeiro is the composition of its foliar epicuticular wax, char- acterized by a high proportion of n-alkanes (78.6%), the most efficient wax constituents against water per- meability. High proportions of n-alkanes (76.5%) also characterize the composition of the foliar epi- cuticular wax of C. yco, although in this species leaf persistence is not observed as Z. joazeiro. Ac- cording to Ferri (1955), specimens of C. yco grow in the shade of other species (Bumelia sartorum Mart. Sapotaceae, Caesalpinia pyramidalis Tul. Leguminosae and Spondias tuberosa Mart, Anacar- diaceae) as a means of adaptation to drought condi- tions. However, after the leaves of these species have been shed, those of C. yco still persist for some time, but not as long as the leaves of Z. joazeiro (Andrade- Lima 1981, Sampaio 1995, Machado 1997). A hy- pothesis that could be speculated at this point is the possibility that the prevalence of n-alkanes in the foliar waxes could be a factor contributing to en- able a lengthier rate of leaf-shade by C. yco. Higher rates of cuticular transpiration by A. pyrifolium than M. rigida have been observed (Ferri 1955). In the
Caatinga is a very important and neglected dry tropical forest biome of Brazil. Recent evidence indicates that anthropogenic threats to Caatinga have grown in recent years, and there are still gaps in the knowledge of how these effects alter biodiversity. In the present study, we evaluated the effects of vegetation structure and edge proximity on the distribution of bioindicator insects (galling insects and ants) in an arboreal Caatinga area under the influence of a monoculture in Brazil. We recorded a total of 10 species and 2,131 specimens of ants and 11 species and 29 individuals of galling insects. Species richness, abundance, and composition of galling insects and ants did not differ between edge and interior plots of the forest. Ant diversity was also not affected by the structural parameters of vegetation (plant abundance, vegetation cover, and vegetation height). On the other hand, the plant abundance positively influenced the richness and the abundance of galling insects in the plots. Our findings suggest that the distribution of ants and galling insects in Caatinga forest edge and interior environments did not differs likely due the opening of the canopy gives the arboreal Caatinga relatively homogeneous climatic characteristics throughout the forest. Already the structure of vegetation positively influences galling insects due to the high degree of dependence that endophagous life-form generates on these insects. Our results show that despite similar responses to the edge effect, ants and galling insects respond differently to vegetation structure, indicating that the structuring of these insect communities is guild-dependent.
Na presente pesquisa pode-se presumir que as espécies D. cearensis e V. farnesiana são mais tolerantes a solos salinos, pelo menos na fase de germinação, e que podem colonizar com sucesso os diferentes ambientes de Caatinga onde ocorrem os solos testados, podendo sua utilização na recuperação com semeadura direta ser viável. Porém, outros estudos avaliando o desenvolvimento dessas espécies nas próximas fases, devem ser realizados para constatações mais assertivas.
The highly seasonal nature of the caatinga is almost cer- tainly a determining factor for above-ground scorpion activity (foraging and/or reproduction) due to the marked influence rainfall and temperature patterns exert on that ecosystem. This contrasts with the situation found for the bothriurid Thestylus aurantiurus Yamaguti & Pinto-da-Rocha, 2003 in the Atlantic Forest. Even though the reproductive period of the species oc- curs during the warm and rainy season, individual abundance is not significantly correlated with temperature or precipita- tion (Y AMAGUTI & P INTO - DA -R OCHA 2006). One explanation for
Phytosociological studies usually survey horizontal and vertical structures, but only the horizontal structure was used in the present work, defining the ten species of greatest importance value (IV). A systematic sampling was made using the fixed plot method, where plots were placed in parallel transects; the transects were10 m apart from each other, and the sample units in the same transect were 25 m apart from each other. The phytosociological study was conducted in an area of 1.0 ha distributed in 40 plots of 10 x 25 m (Barbosa et al., 2012), considering an edge effect of 20 m.
It is assumed that morphological traits of seedlings refl ect diff erent strategies in response to environmental conditions. Th e ecological signifi cance of this has been widely documented in rainforests, where habitat structure and species interactions play an important role in community assembly. However, in seasonally dry ecosystems, where environmental fi ltering is expected to strongly infl uence community structure, this relationship is poorly understood. We investigated this relationship between functional groups of seedlings and life history traits and tested whether functional group predicts the ecological strategies employed by woody species to deal with the stressful conditions in seasonally dry ecosystems. Seedling functional groups, life history traits and traits that refl ect ecological strategies for occupying seasonally dry environments were described for twenty-six plant species. Seedlings of species from the Caatingavegetation exhibited a functional profi le diff erent from that observed in rainforests ecosystems. Phanerocotylar-epigeal seedlings were the most frequently observed groups, and had the largest range of ecological strategies related to dealing with seasonally dry environments, while phanerocotylar-hypogeal-reserve seedlings exhibited an increase in frequency with seasonality. We discuss these results in relation to those observed in other tropical forests and their ecological signifi cance in seasonally dry environments.
Symptoms of decline, dieback and mortality of plant species typical of the Mediterranean maquis were common along slopes downhill of roads and trekking paths in all the three inves- tigated sites within the National Park of La Maddalena archipelago (Fig 1). Juniperus phoenicea was severely affected exhibiting a range of symptoms including partial or complete dieback of the crown and abnormal production of epicormic shoots (Fig 1A), dieback, and reddening or browning of drying foliage on dying and recently dead trees (Fig 1B and 1C). Crown symptoms were often associated with extensive losses of both lateral small woody roots and fine roots and the presence of basal phloem lesions extending up from below ground level (Fig 1D). In low- laying areas with seasonal waterlogging collar and root rot were observed on some juniper trees (Fig 1E). In wetlands, also P. lentiscus showed severe crown thinning and dieback of single branches (Fig 1F), which were associated to root and collar rot. Ground layer species such as A. albus (Fig 1G) and Cistus spp. were also severely affected. Overall, these symptoms were not associated to infections on the upper parts of the plants suggesting that the plants were dying due to a dysfunction and/or destruction of the root system.
Towards a better understanding on how diversity may affect ecosystem properties researchers are increasingly adopting a trait-based approach to analyse the results from BEF studies (Schumacher & Roscher, 2009). This approach assumes that functional traits of constituent species determine the way they explore available resources and respond to the environment, thus are correlated with different and complementary aspects of species niches (McGill, Enquist, Weiher et al., 2006). For example, species that occur in fertile conditions generally produce leaves with high specific leaf area (SLA, leaf area divided by leaf dry mass) and low root-shoot ratio, a strategy related to maximize light exploitation (Wright, Reich, Westoby et al., 2004). On the other hand, those that occur on unproductive soils generally produce leaves with low SLA to prioritize resource conservation (Wright et al., 2004) and forage for resources deep into the soil, increasing root-shoot ratio. With this rationale, communities with high range of trait values (e.g. a variety of SLA values and rooting depths) are considered to possess a wider community niche breadth because resources are being more fully exploited. The full exploitation of resources, for example, by species that growth in different light regimes and/or species that grow roots at several soil depths might lead to increased plant community productivity. Based on this assumption, a trait-based approach can help to unveil which mechanisms are responsible for the positive diversity-productivity relationship.
A região Nordeste do Brasil possui 1.548.672 km 2 de área e cerca de 48,85 milhões de habitantes (IBGE, 2004) e é extremamente heterogênea nos aspectos climáticos e edáficos, apresentando como resultado, ampla variedade de biomas, sendo a Caatinga o mais extenso deles, ocupando uma área de aproximadamente 826.411,23 km 2 , dos quais 81.141 km 2 situam-se em Pernambuco (IBAMA, 2010). A Caatinga, segundo Ab’Saber (1999) e Queiroz (2009), é constituída por espécies vegetais dotadas de longa história de adaptação ao calor e à irregularidade do regime de chuvas, normalmente possuem porte baixo, dossel descontínuo, folhas miúdas e indivíduos com muitas ramificações, geralmente com presença de espinhos ou acúleos para conter os efeitos de uma evapotranspiração muito intensa.
O desmatamento elevado no Bioma Caatinga vem gerando processos de desertificação em diversas áreas, alterando diretamente a biota, o microclima e os solos, sendo fundamental o desenvolvimento de técnicas de pesquisa capazes de incorporar informações que identifiquem o estado dos recursos naturais, apontando os seus relacionamentos e alguns caminhos a serem tomados para uma intervenção eficiente que gere a recupe- ração e o aproveitamento sustentável das terras nesse ambiente. O MTLFC constitui-se em um conjunto de técnicas utilizado pela primeira vez no Brasil para analisar áreas submetidas à desertificação, apresentando indicadores biogeográficos, climatológicos, geomorfológicos e hidrológicos. Através da aplicação do mé- todo em uma área do município de São Domingos do Cariri (PB), foi identificada uma diversidade vegetal muito baixa (13 espécies e 489 indivíduos), dominância de poucas espécies (5) e baixa abundância, com maior número de indivíduos nos estratos arbustivo alto e arbustivo, tendo como causa a retirada excessiva de vegetação, as queimadas e o uso contínuo pelo gado caprino. O Balanço Hídrico apresentou-se negativo, havendo indicação de que a atividade vegetativa depende da precipitação oculta. Os solos apresentaram crosta superficial de origem antrópica, tornando a aridez edáfica ainda mais acentuada, associada aos baixos níveis de fertilidade, particularmente o potássio e a matéria orgânica.
Abstract The aim of this study was to assess the eﬀect of diﬀerent slash management practices on understory biodiversity and biomass in Eucalyptus globulus coppices in Central Portugal. The experiment consisted of four treatments: (a) removal of slash (R), (b) broadcast over the soil (S), (c) as in S but concentrating woody residues between tree rows (W) and (d) incorporation of slash into soil by harrowing (I). Understory vegetation was surveyed during 1–6, 9, and 10 years, the proportion of soil cover by plant species estimated, and diversity and equitability indexes determined. Above ground under- story biomass was sampled in years 2–6, 9, and 10. The highest number of species in most years occurred in plots where slash was removed. Diﬀerences between treat- ments in the proportion of plant soil cover were never signiﬁcant, whereas diﬀerences in diversity index were only occasionally signiﬁcant and apparently related to the number of species. Thus, diﬀerences in the equita- bility index were not signiﬁcant. Understory biomass did not decrease during the rotation period, and was usually highest in R and I, and lowest in S, but not signiﬁcantly diﬀerent. At the end of the rotation period, understory biodiversity indices and biomass were apparently inde- pendent of slash treatment.
For each stand of the chosen agroecosystems, three types of land covers were selected according to the age of the stands. Each agroforest stand was 0-10 years old; 10-20 years and over 20 years. Community sampling units were established to enumerate and identify floristic composition. For each agroforestry system areas, three sites were selected (three times replicated for each site) to establish four 100 × 50 m sampling plots of three stages (0-10, 10-20 and 20+ year old) respectively (Fig. 2). This methodology was similar to that of Du et al. (2015) even though they established nine 20 x 50 m sampling plots of five stages. The survey area was 2 ha per site. Several blocks or squares (quadrates) with definite size (5 x 5 m²) were established in the stands and savannah to identify total number of timbers (Some trees were identified directly in the field using monograph; for other trees, specimens were collected and compared to those available in the National herbarium of Cameroon). The Spatial data layers contours (altitude, slope and aspect) and vegetation types were extracted from topo sheet. Suunto Hypsometer was used for measuring the height of the trees. Likewise, for measuring diameter and circumferences, instruments like Caliper, Finnish Caliper and measuring tape were employed for all woody species (dbh≥2 cm). GPS and compass were used to install and locate stands. The diameter was measured at 1.30 m aboveground for trees and at 0.30 m and 0.50 m for shrublets and shrubs respectively.
All vegetation sites as objects of burning are structural complexes of various fuels. Es- pecially complex are forest biogeoceonoses. For practical use, pyrological characteris- tics of vegetation are reflected on plans and maps showing both general one-sided esti- mations with site descriptions (for example, their fire hazard) and detailed multi-sided characteristics of all compounds in the vegetation fuel complexes. The latter become basic maps for obtaining various pyrological estimations and are called vegetation fuel maps. Vegetation fuel (VF) mapping can be made using two methodological ap- proaches: first, by distinguishing pyrological vegetation categories as standard com- plexes; second, by individually characterizing each vegetation site in terms of VF. Ob- viously, the standard VF characteristic of sites can be only approximate and rough, since the possible number of studied site categories is limited. For large-scale mapping, the detailed individual characteristic of vegetation sites in terms of VF is more prefer- able and precise but more expensive. Therefore, historically, the first approach to VF mapping got its development, i. e. distinguishing and mapping of certain vegetation categories with standard characteristics. Foreign and Russian methodical approaches to vegetation fuel (VF) classification and mapping are considered. Examples of VF map- ping at different scales and guidelines for their use are given.
A possible way to circumvent these difficulties and to conserve Caatinga plant resources is through the use of sym- biotic microorganisms, such as arbuscular mycorrhizal fungi (AMF), which plays a key role in ecosystem maintenance (Heijden et al. 1998). Mycorrhization increases the absorp- tion area around the root by increasing the area of the surface in contact with the soil, increasing the absorption of mineral nutrients, such as phosphorus, zinc, copper, nitrogen, and po- tassium. This higher nutrient acquisition directly influences plant growth and tolerance to environmental stresses (Smith & Read 2008), such as drought stress (Zhu et al. 2012), typical of the semiarid environment of Caatinga biome.