Forest understory vegetation in lowland woodlands is coming through systematical changes, which are documented from many regions. Abandonment of traditional coppicing management, nitrogen deposition and effect of high game densities in some regions are considered to be the main key drivers. Changes of seminatural woodland in protected area of Bohemian Karst were studied in this research. The abandonment of traditional management is probably the biggest environmental change in this area. Original data, semi-permanent plots with phytosociological relevés, were surveyed shortly after the last coppicing in the half of twentieth century. These plots were now re-visited. Partial task was to evaluate how important relocation accuracy is. Discovered changes have similar trends as in other lowland woodlands. After abandonment of coppicing, site conditions changed towards more shade and nutrient rich sites. Vegetation shifted to species assemblages of late succession dominated by shade-adapted and nutrient-demanding species. Slight decrease in gama-diversity, increase in alpha-diversity and decrease of beta-diversity indicated taxonomic homogenization was recorded. Re-visiting of semi-permanent plots was evaluated as appropriate tool for this type of research. Spatial heterogenity is partly affecting temporal change,...

<p>  </p> <p>Alterations to the historic fire regime have contributed to widespread regeneration failure in <em>Quercus</em> L. (oak) forests of the eastern United States. Composition has shifted from <em>Quercus</em> and other fire-adapted species to dominance by mesophytic species. While land managers often focus efforts on restoring <em>Quercus</em> regeneration, the herbaceous layer experiences reduced cover and diversity of herb and graminoid species resulting from the increased woody stem density in fire-suppressed forests. Declining abundance of <em>Quercus</em> species and diversity in the herbaceous layer reduce the overall habitat quality and ecosystem functions provided by the forest. A combination of overstory harvests and prescribed burning are often conducted to restore the plant community in <em>Quercus</em> forests affected by mesophication. Initiated in 2010, our study on the Hoosier National Forest in Indiana conducted shelterwood and midstory (mechanical, chemical, or none) harvests followed by prescribed burning on a less productive site, while leaving a more productive site unburned. Our objective was to evaluate the survival and competitive response of <em>Quercus</em> spp. within the regeneration layer and whether diversity and cover increased in the herbaceous layer following treatments. Using nested circular plots, we measured seedling survival and resprout response, in addition to regeneration density before and after treatments. We measured the percent cover of herbaceous-layer species within quadrats and calculated species richness, evenness, and diversity. Using multiple mixed-effects models, ANOVA, and NMDS ordination, we evaluated woody species regeneration and herbaceous-layer composition before and after treatments. Post-treatment, monitored <em>Quercus</em> spp. seedlings at the burned site displayed greater survival (> 94%) and resprouting (> 92% of monitored stems), which exceeded most competing species, including<em> Acer</em> spp. (~ 59% survival and resprouting) and <em>Fraxinus americana </em>(72% survival and resprouting). <em>Q. alba</em> seedling (< 3.8 cm DBH) densities doubled after burning; it was one of the most abundant species (9,864 stems ha-1) at the burned site. NMDS ordination indicated a clear shift in regeneration species composition with the burn driving a shift away from mesophytic species towards greater importance of <em>Quercus</em> species. Additionally, our burned site had significantly increased herbaceous-layer richness, Shannon diversity index, and total cover compared to pre-treatment. Percent cover increased across all plant functional groups within the herbaceous layer, with trees/shrubs exhibiting the greatest increase. Herbaceous-layer composition at the burned site significantly shifted toward greater importance of graminoids and herbs post-treatment. Post-treatment, the unburned site contained fewer, and less competitive, <em>Quercus</em> seedlings compared to non-<em>Quercus</em> competitors and displayed no significant compositional shifts in seedling species composition post-harvest. Our unburned site exhibited significant, but minor, increases in herbaceous-layer richness, evenness, diversity, and total cover. Herbaceous-layer composition at the unburned site was significantly different post-treatment, shifting towards greater importance of vines, trees/shrubs, and herbs. The more-productive unburned site would likely require multiple burns to produce adequate competitive <em>Quercus</em> seedlings to perpetuate dominance in the developing stand. Burning would also likely result in greater increases in herbaceous-layer diversity compared to harvesting alone. Conversely, the shelterwood, followed by a single burn, on the less productive site had a more substantial effect on the herbaceous layer, and likely produced an adequate density of <em>Quercus</em> reproduction to ensure future dominance by the genus.</p>

Life on Earth is currently experiencing a sixth species extinction, where urbanization, as one of the main driving forces, fragments and causes losses of near-urban habitats. At the same time, a rich variety of habitats can be found in urban landscapes that may harbour biodiversity. Knowledge of how urban ecosystems develops over time is fundamental for application of relevant nature conservation measures that promote species richness. This study aims to shed light on the importance of age in urban residential yards for the species richness of native herbaceous plants and of birds. The study was carried out in Linköping during the summer of 2023, and it included surveys of native herbaceous plants and birds in three area types (natural area, old and young residential yards). In total, 114 species of native herbs and 34 species of birds were found. Sites in the natural area had (mean ± SE) 25,8 (± 1,8) and 6,6 (± 0,7) species of plants and birds respectively, whereas the corresponding values for old residential yards were 23,2 (± 1,2) and 5,7 (± 0,5) and for young residential yards 19,9 (± 1,3) and 3,3 (± 0,7). Jaccard's coefficient showed that the largest proportion of shared species occurred between ‘old’ and 'young' residential yards. Overall, the results of my study showed some support for my prediction that age of residential yards is important for species richness of native herbaceous plants and birds. The results indicate that urban environments (old and young residential yards) harbour a selection of species that can withstand anthropogenic disturbance. / Livet på jorden upplever ett sjätte artutdöende där urbaniseringen, som en av de främsta drivkrafterna, fragmenterar och orsakar förluster av stadsnära habitat. Samtidigt finns en rik variation av livsmiljöer i stadslandskap som hyser en biologisk mångfald. Kunskap om hur urbana ekosystem utvecklas över tid är grundläggande för tillämpning av relevanta naturvårdsåtgärder i staden som främjar artrikedom. Denna studie syftar till att belysa betydelsen av urbana bostadsgårdars ålder för artrikedomen hos inhemska örtartade växter och fåglar. Studien genomfördes i Linköping under sommaren 2023 och omfattade inventeringar av inhemska örtartade växter och fåglar i tre områdestyper (naturområde, äldre och unga bostadsgårdar). Totalt hittades 114 arter av inhemska örter och 34 arter av fåglar. Naturområdet hade (medelvärde ± SE) 25,8 (± 1,8) respektive 6,6 (± 0,7) arter av växter och fåglar, medan motsvarande värden för äldre bostadsgårdar var 23,2 (± 1,2) och 5,7 (± 0,5) och för unga bostadsgårdar 19,9 (± 1,3) och 3,3 (± 0,7). Jaccards koefficient visade att den största andelen överlappande arter förekom mellan ’äldre’ och ’unga’ bostadsgårdar. Sammantaget visade resultaten av min studie ett visst stöd för min förutsägelse att bostadsgårdarnas ålder är av betydelse för artrikedomen hos inhemska örtartade växter och fåglar. Resultaten tyder på att stadsmiljöer (äldre och unga bostadsgårdar) hyser ett urval av arter som tål antropogena, av människan orsakade, störningar.

Over the last 20 years, Lyme disease has grown to become the most common vector-borne disease affecting Americans. Spread in the eastern U.S. primarily by the bite of Ixodes scapularis, the black-legged tick, the disease affects an estimated 329,000 Americans per year. Originally confined to New England, it has since spread across much of the east coast and has become endemic in Virginia. Since 2010 the state has averaged 1200 cases per year, with 200 annually in the New River Health District (NRHD), the location of our study. Efforts to geographically model Lyme disease primarily focus on landscape and climatic variables. The disease depends highly on the survival of the tick vector, and white-footed mouse, the primary reservoir. Both depend on the existence of forest-herbaceous edge-habitats, as well as warm summer temperatures, mild winter lows, and summer wetness. While many studies have investigated the effect of forest fragmentation on Lyme, none have made use of high-resolution land cover data to do so at the peridomestic level. To fill this knowledge gap, we made use of the Virginia Geographic Information Network’s 1-meter land cover dataset and identified forest-herbaceous edge-habitats for the NRHD. We then calculated the density of these edge-habitats at 100, 200 and 300-meter radii, representing the peridomestic environment. We also calculated the density of <2-hectare forest patches at the same distance thresholds. To avoid confounding from climatic variation, we also calculated mean summer temperatures, total summer rainfall, and number of consecutive days below freezing of the prior winters. Adding to these data, elevation, terrain shape index, slope, and aspect, and including lags on each of our climatic variables, we created environmental niche models of Lyme in the NRHD. We did so using both Boosted Regression Trees (BRT) and Maximum Entropy (MaxEnt) modeling, the two most common niche modeling algorithms in the field today. We found that Lyme is strongly associated with higher density of developed-herbaceous edges within 100-meters from the home. Forest patch density was also significant at both 100-meter and 300-meter levels. This supports the notion that the fine scale peridomestic environment is significant to Lyme outcomes, and must be considered even if one were to account for fragmentation at a wider scale, as well as variations in climate and terrain. / M.S. / Lyme disease is the most common vector-borne disease in the United States today. Infecting about 330,000 Americans per year, the disease continues to spread geographically. Originally found only in New England, the disease is now common in Virginia. The New River Health District, where we did our study, sees over 200 cases per year. Lyme disease is mostly spread by the bite of the black-legged tick. As such we can predict where Lyme cases might be found if we understand the environmental needs of these ticks. The ticks themselves depend on warm summer temperatures, mild winter lows, and summer wetness. But they are also affected by forest fragmentation which drives up the population of white-footed mice, the tick’s primary host. The mice are particularly fond of the interface between forests and open fields. These edge habitats provide food and cover for the mice, and in turn support a large population of ticks. Many existing studies have demonstrated this link, but all have done so across broad scales such as counties or census tracts. To our knowledge, no such studies have investigated forest fragmentation near the home of known Lyme cases. To fill this gap in our knowledge, we made use of high-resolution forest cover data to identify forest-field edge habitats and small isolated forest patches. We then calculated the total density of both within 100, 200 and 300 meters of the homes of known Lyme cases, and compared these to values from non-cases using statistical modeling. We also included winter and summer temperatures, rainfall, elevation, slope, aspect, and terrain shape. We found that a large amount of forest-field edges within 100 meters of a home increases the risk of Lyme disease to residents of that home. The same can be said for isolated forest patches. Even after accounting for all other variables, this effect was still significant. This information can be used by health departments to predict which neighborhoods may be most at risk for Lyme. They can then increase surveillance in those areas, warn local doctors, or send out educational materials.

Herbivores have a significant influence on their environment. Factors that influence herbivore distribution in a landscape are important for conservation. Artificial water provision is one such factor, with water sources being focal points of herbivore activity. Variation between herbivore utilisation of different waterhole types and habitat integrity surrounding the different waterholes is assessed in this study. Correlations are drawn between herbivore utilisation and habitat integrity to quantify the impact that artificial waterholes have on the landscape. A scoring system is devised to investigate the various factors affecting vegetation around artificial waterholes. Results show that there are significant variations between herbivore utilisation for different artificial waterhole types, as well as significant variation in habitat integrity surrounding the different waterhole types. Distance between waterholes and drainage lines, and utilisation by specific herbivore species have a significant impact on habitat integrity - specifically affecting veld condition and disturbance observed on woody plant species. A habitat score that was created by combining data from both the herbaceous and woody layers is not affected by waterhole type, distance from waterholes, or the different herbivore species utilising the different waterhole types. Earth dams have the greatest impact on surrounding vegetation and are the most utilised waterhole type. Closures of earth dams are not recommended due to their importance to herbivores. Less utilised waterhole types are also important, mitigating the impact of herbivore damage to vegetation at earth dams. / Environmental Sciences / M. Sc. (Nature Conservation)

The work drala with the theoretical design bio-centers, the composition of vegetation in it and machanization means with which it could be bulit bio-center. The theoretical part contains the characteristics of concepts, the characteristics for which the proposed bio-center and track stands. The practical part contains procedures for setting up bio-centers, design of machinery and design of care of forests based on bio-centers.

Made available in DSpace on 2016-06-02T19:29:23Z (GMT). No. of bitstreams: 1 3063.pdf: 3377110 bytes, checksum: fda162bf60bb5679d2f8f4cfb07989b1 (MD5) Previous issue date: 2010-05-06 / Considered as alternative management more appropriate for tropical conditions, the no-tillage system can follow the principles of organic agriculture and contribute to the evolution and sustainability of organic cotton production systems. In order to generate usage information about soil covering plants for white and colored cotton fibers production in the organic system with no-tillage, an experiment was conducted in the farming years 2006/07 and 2007/08 in Cáceres-MT, with randomized block design, treatments disposed in scheme of split plots and four replicates. In the plots, were evaluated soil coverage consisting of crop residues of Estilozobium aterrimum, Cajanus cajan, Canavalia ensiformes, Crotalaria juncea, Pennisetum glaucum cv ADR 300, Sorghum bicolor cv BRS 307, mixture of species used, spontaneous vegetation and exposed soil. In the sub plots were evaluated upland cotton cultivars BRS ITAUBA (white) and CNPA AMT 19 (brown) in no-tillage on the crop residues of the soil covering plants cultivated in pre-planting. The plant coverage produces phytomass in sufficient quantities for adequate soil coverage. The Estilozobium aterrimum, in a general manner, shows greater extraction capacity and accumulation of nutrients, high lighting the potential cycling of nitrogen and phosphorus, while Pennisetum glaucum and Crotalaria show, respectively, greater potential cycling of potassium and magnesium. The crop residues of Canavalia ensiformes, spontaneous vegetation and Crotalaria provide low persistence coverage, while Pennisetum glaucum residues and Cajanus cajan provide more persistent coverage. During the process of residues decomposition, the nutrients following this descending order of release: K > P > N = S > Mg > Ca, being the potassium the nutrient with faster release and subject to losses. The Estilozobium aterrimum shows greater weed suppression capacity, showing potential for use in production system without application of herbicides, in contrast with the low suppression capacity of Pennisetum glaucum plants and spontaneous vegetation. The contribution of plant coverage residues promote on the surface layer of soil increases in values of attributes pH, MOS, P, K, Ca, Mg, V e CTC. The coverage does not influence the characteristics of fibers, but exerts significant effects on agronomic characteristics and productivity of cotton. The highest yield occurs in straws of Crotalaria juncea, Canavalia ensiformes, Estilozobium aterrimum and mixture of species. The cotton cultivars of brown fiber (CNPA AMT 19) shows productivity and quality of fiber lower than the cultivars of white fiber (BRS ITAÚBA), however has fibers with characteristics that meet the standards required by the textile industry. / Considerado como alternativa de manejo mais adequada para as condições tropicais, o sistema plantio direto pode seguir os princípios da agricultura orgânica e contribuir para a evolução e sustentabilidade dos sistemas de produção orgânica de algodão. Com o objetivo de gerar informações sobre o uso de plantas de cobertura de solo para a produção de algodão de fibras brancas e coloridas no sistema orgânico com plantio direto, foi conduzido um experimento nos anos agrícolas 2006/07 e 2007/08 em Cáceres-MT, com delineamento de blocos casualizados, tratamentos dispostos em esquema de parcelas subdivididas e quatro repetições. Nas parcelas avaliaram-se coberturas de solo constituídas por resíduos culturais de mucuna preta (Estilozobium aterrimum), feijão guandu anão (Cajanus cajan), feijão de porco (Canavalia ensiformes), crotalária juncea (Crotalaria juncea), milheto (Pennisetum glaucum cv ADR 300), sorgo granífero (Sorghum bicolor cv BRS 307), coquetel das espécies utilizadas, vegetação espontânea e solo exposto. Nas subparcelas avaliaram-se as cultivares de algodoeiro herbáceo BRS ITAÚBA (branco) e CNPA AMT 19 (marrom) em plantio direto sobre os resíduos culturais das plantas de cobertura de solo cultivadas em pré-plantio. As plantas de cobertura produzem fitomassa em quantidades suficientes para uma adequada cobertura de solo. A mucuna preta, de modo geral, apresenta maior capacidade de extração e acúmulo de nutrientes, destacando-se quanto ao potencial de ciclagem de nitrogênio e fósforo, enquanto o milheto e a crotalária apresentam, respectivamente, maior potencial de ciclagem de potássio e magnésio. Os resíduos culturais do feijão de porco, vegetação espontânea e crotalária proporcionam coberturas de baixa persistência, enquanto os resíduos de milheto e guandu anão proporcionam coberturas mais persistentes. Durante o processo de decomposição dos resíduos, os nutrientes seguem a seguinte ordem decrescente de liberação: K > P > N = S > Mg > Ca, sendo o potássio o nutriente de liberação mais rápida e sujeito a perdas. A mucuna preta apresenta maior capacidade de supressão de plantas invasoras, evidenciando potencial para uso em sistemas de produção sem aplicação de herbicidas, contrastando com a baixa capacidade de supressão do milheto e da vegetação espontânea. O aporte de resíduos de plantas de cobertura promove na camada superficial do solo aumento nos valores dos atributos pH, MOS, P, K, Ca, Mg, V e CTC. As coberturas não influenciam nas características de fibras, mas exercem efeitos significativos nas características agronômicas e na produtividade de algodão. As maiores produtividades ocorrem nas palhadas da crotalária juncea, feijão de porco, mucuna preta e coquetel de espécies. A cultivar de algodão de fibras marrom (CNPA AMT 19) apresenta produtividade e qualidade de fibra inferior à da cultivar de fibra branca (BRS ITAÚBA), porém suas fibras possuem características que atendem os padrões requeridos pela indústria têxtil.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research was conducted in a fragment of Caatinga with around 50 ha in São Pedro farm, located at Porto da Folha City, Sergipe, order to know the floristic composition and phytossociological structure of herbaceous and shrub-tree components, verify the relationships physiognomic of the shrub-tree with other Caatinga areas, as well as the existence of edge effect in the fragment studied, with the intention of generate subsidies to studies of ecology, conservation and recovery of degraded areas in the region. Thus, it was tested the following null hypotheses: 1st - there is no difference in the structure and richness of shrub-tree of fragment studied in comparison with other areas of Caatinga analyzed in Sergipe and in the Northeast; 2nd - there is no difference in the floristic composition and phytossociological structure of herbaceous vegetation between two seasons (dry and wet); 3rd - there is no difference in the floristic composition and structure of the shrub-tree between edge and interior of the fragment Caatinga studied. For testing the first hypothesis, it was conducted sampling of shrub- tree through of 25 plots, with 20x20m (400m²), distributed systematically at intervals of 141 m in two directions perpendicular to each plot. All individuals of shrubs-trees were identified and recorded with at breast height circumference (BHC at 1.30 m from ground level) ≥ 6.0 cm and analyzed the floristic composition, the phytossociological structure (density, frequency, dominance and importance value), diversity in addition to spatial distribution and floristic similarity. Species richness and structural parameters of the component of shrubs-trees found in the fragment studied was higher than in most surveys in other areas of Caatinga dominium, considering the different types analyzed ( Caatinga Caducifólia Espinhosa , Caatinga Caducifólia Não Espinhosa and Vegetação Estacional Decidual ). The vegetation that was in the fragment studied can be classified as Caatinga Caducifólia Espinhosa (Caatinga sensu stricto) showed the highest similarity to other semiarid areas that have this same type of plant formation. For testing the second hypothesis, two samples were realized of the herbaceous component for comparison, in the rainy season and one during the dry season on 25 smaller plots with 1x1 m (1m ²) distributed systematically within plots of 20x20m, a distance of 10 meters, following is the angle of 45° from the first vertex of each plot. All living plants were measured and identified with stem/pseudo-stem chlorophyll with absence or low level of lignifications that were not seedlings of woody species and analyzed the floristic composition, the phytossociological structure (density, frequency, dominance and importance value), diversity in addition to life forms of Raunkiaer. The density, frequency, dominance and importance value of herbaceous populations, as well as height and diameter of plants were low in the dry season. The diversity of herbaceous species recorded for the fragment was more than most of the studies that was done in other areas of Caatinga of Northeast Brazil, which can be associated to good state of conservation of the studied fragment. The life-form predominant of vegetation was the therophytes, followed by phanerophytes, featuring a therophytic phytoclimate to the region of the study area. The analysis of structural patterns and diversity conducted only in two distinct seasons are not enough to know, in detail, the ecological dynamics of the herbaceous component of caatinga in the fragment studied. For test the third hypothesis were selected 24 permanent plots with 20x20 m, being 12 marked in the edge and 12 inside the fragment, in a systematic manner, at intervals of 141 m. In each plot were identified and recorded all individuals of shrubs and trees with at breast height circumference (BHC at 1.30 m from xii ground level) ≥ 6.0 cm and measured variables dendrometric for the calculations of diversity and structure, addition to these variables was calculated leaf area index using hemispherical photos with the lens "fisheye" 180 ° in the center of each plot. We used non-metric multidimensional scaling (NMDS) to check whether there are differences in species composition between plots of the edge and interior. To determine the floristic similarity between plots evaluated in different environments, we used the similarity analysis (ANOSIM). Differences between the sampled environmental variables (dependent variables) in relation to the location of the edge and interior plots (independent variable) were tested using generalized linear models (GLM's). The plots of edge presented 43 species and 1157 individuals, while the interior of the 1377 individuals and 42 species. The NMDS ordination showed that there are not clear differences in species composition between the two environments analyzed (edge and interior). The five structural parameters vegetation analyzed between plots located the edges and interior the fragment (tree height, stem diameter, basal area, number of individuals and leaf area index) did not result in statistically significant differences. In relation to the richness, diversity species and evenness indexes was verified also that there is no statistically significant difference between the environment the edge and interior. The physiognomic and structural similarities of vegetation in the study area, evidenced by the richness, abundance and distribution of species in different locations (edge and interior), suggest the existence of a common pattern, possibly related to the availability of resources in an equitable manner (as light, water and nutrients), history of conservation of the vegetation of the fragment, as well as the heterogeneity and complexity of the environmental area. Indicating that the community arbustivo-arboreal of the fragment of Caatinga studied is not ecologically affected by the presence of the edges. / O presente trabalho foi realizado em um fragmento de Caatinga com aproximadamente 50 ha, pertencente à fazenda São Pedro, localizada no município de Porto da Folha, Sergipe, objetivando conhecer a composição florística e a estrutura fitossociológica do componente herbáceo e arbustivo-arbóreo, verificar as relações fitofisionômicas do estrato arbustivo-arbóreo com outras áreas de Caatinga, bem como a existência de efeito de borda no fragmento estudado, com o intuito de gerar subsídios aos estudos de ecologia, conservação e recuperação de áreas degradadas na região. Deste modo foram testadas as seguintes hipóteses nulas: 1ª - não existe diferença na riqueza e estrutura da vegetação arbustivo-arbóreo do fragmento estudado em relação a outras áreas de Caatinga analisadas em Sergipe e no Nordeste; 2ª - não existe diferença na composição florística e estrutura fitossociológica do estrato herbáceo entre duas estações do ano (seca e chuvosa); 3ª - não existe diferença na composição florística e estrutura do estrato arbustivo-arbóreo entre borda e interior do fragmento de Caatinga estudado. Para testar a primeira hipótese foi realizada a amostragem da vegetação arbustivo-arbórea por meio de 25 parcelas, com 20x20m (400m²), distribuídas sistematicamente a intervalos de 141 m em duas direções perpendiculares entre cada parcela. Foram identificados e registrados todos os indivíduos arbustivo-arbóreos com circunferência à altura do peito (CAP a 1,30m do nível do solo) ≥ 6,0 cm e analisadas a composição florística, a estrutura fitossociológica (densidade, frequência, dominância e valor de importância), a diversidade, além da distribuição espacial e similaridade florística. A riqueza de espécies e os parâmetros estruturais do componente arbustivo-arbóreo encontrados no fragmento estudado foram superiores à maioria dos levantamentos em outras áreas do domínio Caatinga, considerando-se as diferentes tipologias analisadas (Caatinga Caducifólia Espinhosa, Caatinga Caducifólia Não Espinhosa e Vegetação Estacional Decidual). Para testar a segunda hipótese foram realizadas duas amostragens do componente herbáceo para comparação, uma na estação chuvosa e outra na seca, em 25 subparcelas, com 1x1m (1m²), distribuídas sistematicamente dentro de parcelas de 20x20m, a uma distância de 10 metros, seguindo-se a angulação de 45º a partir do primeiro vértice de cada parcela. Foram mensuradas e identificadas todas as plantas vivas com caule/pseudocaule clorofilado, com ausência ou baixo nível de lignificação que não fossem plântulas de espécies lenhosas e analisadas a composição florística, a estrutura fitossociológica (densidade, frequência, dominância e valor de importância), a diversidade, além das formas de vida de Raunkiaer. A densidade, freqüência, dominância e valor de importância das populações herbáceas, bem como, a altura e o diâmetro das plantas foram menores na estação seca. A diversidade de espécies herbáceas registrada para o fragmento foi superior a maioria dos trabalhos realizados em outras áreas de Caatinga do Nordeste brasileiro, fato que possivelmente pode estar associado ao bom estado de conservação do fragmento estudado. A forma de vida predominante da vegetação foi o terófito, seguido do fanerófito, caracterizando um fitoclima terofítico-fanerofítico para a região da área de estudo. A análise dos padrões estruturais e de diversidade realizados apenas em duas estações distintas não são suficientes para conhecer, de forma aprofundada, a dinâmica ecológica do componente herbáceo da caatinga no fragmento estudado. Para testar a terceira hipótese foram selecionadas 24 parcelas de área fixa com 20x20 metros, sendo 12 demarcadas na borda e 12 no interior do fragmento, de modo sistemático, a intervalos de 141 m. Em cada parcela foram identificados e registrados todos os indivíduos arbustivo-arbóreos com circunferência à altura do peito (CAP a 1,30m do nível do solo) ≥ 6,0 cm e mensuradas as variáveis dendrométricas para a realização dos cálculos de diversidade e estrutura, além x dessas variáveis foi calculado o índice de área foliar por meio de fotos hemisféricas com a lente olho de peixe de 180º no centro de cada parcela. Foi utilizado o escalonamento multidimensional não métrico (NMDS) para verificar a existência ou não de diferença na composição de espécies entre as parcelas da borda e do interior. Para a determinação da similaridade florística entre as parcelas avaliadas nos diferentes ambientes, foi utilizada a análise de similaridade. Diferenças entre as variáveis ambientais amostradas (variáveis dependentes) em relação à localização das parcelas de borda e interior, (variável independente) foram testadas usando modelos lineares generalizados (GLM´s). As parcelas de borda apresentaram 1157 indivíduos e 43 espécies, enquanto as do interior, 1377 indivíduos e 42 espécies. A ordenação NMDS mostrou que não existem diferenças claras na composição de espécies entre os dois ambientes analisados (borda e interior). Os cinco parâmetros estruturais da vegetação analisados entre as parcelas localizadas na borda e no interior do fragmento (altura das árvores, diâmetro do fuste, área basal, número de indivíduos e índice de área foliar) não resultaram em diferenças estatísticas significativas. Em relação aos índices referentes à riqueza, diversidade de espécies e equabilidade verificou-se, também, que não existe diferença estatística significativa entre o ambiente da borda e do interior. As semelhanças fisionômicas e estruturais da vegetação na área de estudo, evidenciadas pela riqueza, abundância e distribuição das espécies nos diferentes locais (borda e interior), sugerem a existência de um padrão comum, relacionado possivelmente com a disponibilidade de recursos de forma igualitária (como luz, água e nutrientes), histórico de conservação da vegetação do fragmento, bem como pela heterogeneidade e complexidade ambiental da área, indicando que a comunidade arbustivo-arbórea do fragmento de Caatinga não é ecologicamente afetada pela presença das bordas.

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