ABSTRACT
Abstract A transect was used to examine the environmental and biological descriptors of a compact vegetation mosaic in the Chapada Diamantina in northeastern Brazil, including the floristic composition, spectrum of plant life forms, rainfall, and soil properties that defined areas of cerrado (Brazilian savanna), caatinga (seasonally dry tropical forest thorny, deciduous shrub/arboreal vegetation) and cerrado-caatinga transition vegetation. The floristic survey was made monthly from April/2009 to March/2012. A dendrogram of similarity was generated using the Jaccard Index based on a matrix of the species that occurred in at least two of the vegetation types examined. The proportions of life forms in each vegetation type were compared using the chi-square test. Composite soil samples were analyzed by simple variance (ANOVA) to examine relationships between soil parameters of each vegetation type and the transition area. The monthly precipitation levels in each vegetation type were measured and compared using the chi-square test. A total of 323 species of angiosperms were collected distributed in 193 genera and 54 families. The dendrogram demonstrated strong difference between the floristic compositions of the cerrado and caatinga, sharing 2% similarity. The chi-square test did not demonstrate any significant statistical differences between the monthly values of recorded rainfall. The organic matter and clay contents of the soilsin the caatinga increased while sand decreased, and the proportions of therophyte, hemicryptophyte, and chamaephyte life forms decreased and phanerophytes increased. We can therefore conclude that the floristic composition and the spectrum of life forms combined to define the cerrado and caatinga vegetation along the transect examined, with soil being the principal conditioning factor determining the different vegetation types, independent of precipitation levels.
Resumo Foi estabelecida uma transecção para examinar descritores ambientais e biológicos em uma área compacta de vegetação em mosaico na Chapada Diamantina, Nordeste do Brasil. A composição florística, espectro de formas de vida, precipitação e propriedades do solo foram avaliadas na transecção entre cerrado (savana brasileira) e caatinga (floresta tropical sazonalmente seca espinhosa, vegetação arbustivo-arbórea decídua), separados por vegetação de transição cerrado-caatinga. O levantamento florístico foi realizado mensalmente de abril de 2009 a março de 2012. Foi feita análise de agrupamento a fim de determinar a similaridade entre as fisionomias de cerrado, a caatinga e a transição cerrado-caatinga. As proporções de formas de vida foram comparadas utilizando o teste qui-quadrado. Amostras compostas de solo foram analisadas por variância simples (ANOVA) testando a existência de diferenças entre os solos de cada tipo de vegetação. A precipitação mensal em cada tipo de vegetação foi mensurada e os resultados comparados com o teste qui-quadrado. Coletamos 323 espécies de angiospermas pertencentes a 193 gêneros e 54 famílias. A análise de agrupamento demostrou diferença entre a composição florística do cerrado e da caatinga, com apenas 2% de similaridade. O teste qui-quadrado não demonstrou diferença estatística entre os valores registrados para cada mês. À medida que os conteúdos de matéria orgânica e argila aumentaram e o de areia diminuiu na caatinga, a proporção das formas de vida terófito, hemicriptófito e caméfito diminuiu e a de fanerófitos aumentou. Podemos considerar que a composição florística e o espectro de formas de vida delimitaram o cerrado e a caatinga na transecção estudada e que o solo foi o principal fator condicionante para determinação dos diferentes tipos de vegetação, independentemente da precipitação.
Subject(s)
Soil/classification , Forests , Embryophyta/classification , Rain , Brazil , Statistics as Topic , Ecosystem , Parks, Recreational/statistics & numerical dataABSTRACT
Vascular species and their respective life-forms and coverage were recorded in a Brazilian quartzite and itabirite rocky outcrop site at Serra de Ouro Preto, producing the floristic, frequency and vegetational spectra. Three habitats in both lithologies were defined by geomorphology as: 1) Sloped areas near the mountain summit, with grasslands; 2) Plateaus in the middle of the slope, with grasslands; and 3) Lower and/or concave parts of the slopes, with woody savannas. The life-forms followed Raunkiaer's System. We aimed to answer the following questions: Do quartzite and itabirite rocky outcrops have different biological spectra? Are the biological spectra different in the geomorphologic habitats? Do the floristic, vegetational and frequency spectra differ from one another? What spectrum stacks up to a rocky outcrop physiognomy description? The results portrayed that: a) the most represented life-forms were the phanerophytes and hemicryptophytes; b) the floristic and frequency spectra did not differ from each other, but both differed from the vegetational one; c) all the floristic spectra were similar, but there were significant differences in the frequency and vegetational spectra among the lithology and geomorphology habitats; d) higher phanerophyte and lesser hemicryptophyte coverages were found in the itabirite areas and also in the lower or concave parts of the slopes of both lithologies; and e) the vegetational spectrum was more efficient for the studied rocky outcrop comparison. Relationships between the environmental aspects and life-form spectra are discussed. This study will help advance the development of restoration projects for these areas by adding knowledge of their flora composition, structure and function.
Realizou-se um levantamento das espécies vasculares e suas respectivas formas de vida e coberturas, em campos rupestres na Serra de Ouro Preto, sobre quartzito e itabirito, para construção dos espectros florísticos, de freqüência e vegetacional. Em cada litologia foram delimitados, pela geomofologia, três tipos de habitats: 1) Áreas inclinadas, nos topos das montanhas, com campos limpos; 2) Platôs, na parte mediana das encostas, com campos limpos e 3) Partes mais baixas ou côncavas das encostas, com campos sujos. As formas de vida seguiram o sistema de Raunkiaer. Averiguaram-se as seguintes questões: Campos rupestres sobre itabirito e quartzito possuem diferentes espectros biológicos? Os habitats estratificados pela geomorfologia diferem quanto aos espectros biológicos? Os espectros florísticos, de frequência e vegetacional diferem entre si? Qual espectro se destaca como descritor da fisionomia de campos rupestres? Os resultados evidenciaram que: a) fanerófitas e hemicriptófitas são as formas de vida predominantes; b) os espectros florísticos e de frequência não diferiram entre si e ambos foram estatisticamente diferentes do espectro vegetacional; c) os habitats estratificados pela litologia e geomorfologia apresentaram espectros florísticos similares, mas os espectros de frequência e vegetação mostraram diferenças significativas; d) maior cobertura de fanerófitas e menor cobertura de hemicriptófitas foram encontradas nas áreas sobre itabirito, assim como nas partes mais baixas ou côncavas das encostas, em ambas litologias; e e) o espectro vegetacional mostrou-se mais eficiente para comparação dos habitats. Aspectos do ambiente relacionados com a distribuição de formas de vida são discutidos. Este estudo subsidia programas de restauração ambiental, ampliando o conhecimento da vegetação de campos rupestres.
ABSTRACT
<p><b>OBJECTIVE</b>To determine the present status of plant communities and their possible association with the habitat in Malam Jabba, Swat, Pakistan.</p><p><b>METHODS</b>A study on the phytoecology was conducted in various ecologically important sites of Malam Jabba, Swat, Pakistan from 2002 to 2004. The altitude of these sites ranged from 1 200 m to 3 200 m. Quadrat method was used for evaluation of plants communities and the data on these attributes was converted to relative values. The plant communities were named after 3 leading species with highest importance values. Biological spectrum of the flora based on the life form was prepared by following Raunkiar's life form classes.</p><p><b>RESULTS</b>The floristic composition and structure of the study area were found to be 200 species belonging to 75 families. Asteraceae, Lamiaceae and Poaceae were important families in the study area. The biological spectrum showed that therophytic and hemicrytophytic life form and micro-nonophyllous leaf sizes were dominant in the area. The air and soil temperatures were decreasing with increasing elevation. Both the air and soil temperatures were relatively higher in south slopes than on the northeast slopes. The vegetation analysis of the area indicated eleven plant communities around the area. The present vegetation is the relics of moist temperate coniferous forest in the area. The communities reflect highly deteriorated conditions. Both the structure and composition of the surrounding vegetation were associated with the types of habitats.</p><p><b>CONCLUSIONS</b>The conservation of the remaining populations of the reported communities will be best achieved by proper time of sustainable harvesting. It is only possible with the participation of local communities.</p>