Pantanal é considerado uma das maiores áreas úmidas no interior do continente Sul-Americano e, ao passar por ciclos anuais de inundação, sua extensa área é colonizada por espécies adaptadas aos diversos ambientes, que variam desde terrestres, sazonalmente alagados e aquáticos. Considerando que as variáveis pedológicas, geomorfológicas e o regime hídrico influenciam diretamente no desenvolvimento da comunidade vegetal, este estudo investigou os primeiros 20 cm do solo como fator de diferenciação de fitofisionomias nas unidades da paisagem do Pantanal do Abobral, estado do Mato Grosso do Sul, Brasil. Foram coletadas amostras simples (0-20 cm) de solo, com cinco repetições, em cada unidade de paisagem (Geoambientes), realizando-se análises físicas e químicas. Na Cordilheira, ambiente levemente elevado e livre de inundação, há presença de solo naturalmente fértil e básico, que suporta o estabelecimento de floresta semidecídua com sub-bosque. Na planície de inundação, no Corixo, há presença de mata ciliar sobre solo com características redutoras; na Lagoa Intermitente a constante saturação hídrica favorece vegetação tolerante à inundação e macrófitas aquáticas; enquanto o Campo com Cambará, porção sazonalmente alagada, apresentou a menor fertilidade natural, sendo recoberto por gramíneas e processo inicial de colonização por Vochysia divergens (Myrtales, Vochysiaceae). O estudo demonstrou que as descontinuidades da paisagem e nas formações vegetais são correlacionadas às características físicas e químicas dos solos, provando serem um dos principais estratificadores do ambiente, ao lado do nível do lençol freático, sempre próximo à superfície, característica marcante do Pantanal. Palavras-chave: áreas úmidas; estratificação de ambientes; relação solo-vegetação; variáveis pedológicas. EDAPHIC GRADIENT AND PHYTOPHYSIOGNOMIES OF PANTANAL DO ABOBRAL, BRAZIL. Pantanal is considered one of the largest wetlands inside South America continent. Through the seasonally flood cycles, Pantanal landscape changes in terrestrial, seasonally flooded and aquatic environments, and is colonized by aquatic and terrestrial species. Pedological and geomorphological factors, as well as the water table fluctuation, directly determine plants communities. Thus, this paper investigated the upper soil layer (depth 0-20 cm) as a phytophysiognomies differentiation factor inside Pantanal do Abobral, state of Mato Grosso do Sul, Brazil. Soil samples were collected (0-20 cm), in replicates of five, in each of four different landscape Queiroz et al. | 731
The use of photogrammetry technology for aboveground biomass (AGB) stock estimation in tropical savannas is a challenging task and is still at a preliminary stage. This work aimed to use metrics derived from point clouds, constructed using photogrammetric imaging obtained by an RGB camera on board a remotely piloted aircraft (RPA), to generate a model for estimating AGB stock for the shrubby-woody stratum in savanna areas of Central Brazil (Cerrado). AGB stock was estimated using forest inventory data and an allometric equation. The photogrammetric digital terrain model (DTM) was validated with altimetric field data, demonstrating that the passive sensor can identify topographic variations in sites with discontinuous canopies. The inventory estimated an average AGB of 18.3 (±13.3) Mg ha−1 at the three sampled sites. The AGB model selected was composed of metrics used for height at the 10th and 95th percentile, with an adjusted R2 of 93% and a relative root mean squared error (RMSE) of 16%. AGB distribution maps were generated from the spatialization of the metrics selected for the model, optimizing the visualization and our understanding of the spatial distribution of forest AGB. The study represents a step forward in mapping biomass and carbon stocks in tropical savannas using low-cost remote sensing platforms.
The Pantanal basin is seasonally flooded in different degrees in space and time, overflowing most part of the lowland and forming distinct landscape units or geo-environments. The Abobral Pantanal is one of the Pantanal sub-regions. This study aimed to classify and report soil physic-chemical characteristics and evaluate the soil-plant relations. We subdivided the landscape using hydromorphism, phytophysiognomies, relief, and soil conditions. The Abobral Pantanal was stratified in four geo-environments: Cordilheiras with semi deciduous forest over Chernozems with petrocalcic horizon; Corixo with flooded forest over Planosols with vertic character; Campo com Cambará over Planosols with gley character; and Lagoa Intermitente over eutrophic Planosols. At Cordilheira geo-environment, a non-flooded area, occurred snail shells buried in the soil at mean depth 55-80 cm, inducing occurrence of base rich Chernozems. At Cordilheiras there is occurrance of calcite, mica, smectites and albite. The high pH, the drain obstruction, and abundant occurrance of Ca and Mg in soluble forms in the soil allows high stability to the snail shells. At the seasonally flooded geoenvironments the planic B horizon supports the maintenance of a higher water table. At these seasonally flooded geo-environments occurs micas, smectites, calcite, microcline, caulinite and quartz. At Cordilheiras, the snail shells dissolution above petrocalcic horizons are not the main ion source for petrocalcic horizon formation. The Mg soil richness indicates other non-biogenic carbonate source. The calcareous higher lands around Pantanal are likely responsibles for enrich the water flood at Abobral Pantanal. Sediments dating above and below the petrocalcic horizon points to 2500 BP the most likely time of the petrocalcic formation. At that time, the Pantanal basin were probably drier with a lower drainage, which would favor a cemented strata formation. Snail shells dating indicates mean age of 1700 BP, its deposition it is not considered anthropic. Petrocalcic horizon and Chernozems formations were not simultaneously. After the petrocalcic resposible event there was younger materials deposition, about 600 BP. Petrocalcic horizon partial degradation, allied to soil bioturbation originated Chernozems.
A depressão do Pantanal está sujeita à inundação anual, alagando a maior parte da planície e criando enorme heterogeneidade de unidades da paisagem ou de geoambientes. O Pantanal do Abobral é uma sub-região que compõe o Pantanal. O estudo teve como objetivo caracterizar as unidades ambientais do Pantanal do Abobral, utilizando-se de atributos físico-químicos dos solos. A paisagem foi estratificada pelas condições de hidromorfismo, fitofisionomia, relevo e solos. No Geoambiente Cordilheira, área não alagável, verificou-se ocorrência de conchas de caramujos enterradas no solo, o que influenciou na presença de Chernossolos. Esse Geoambiente apresentou os maiores estoques de C-org e de teores de fósforo disponíveis. A ocorrência de horizontes petrocálcicos nas Cordilheiras contribui para a deciduidade da vegetação e para a estabilidade daquelas frente aos processos erosivos. Nos ambientes sazonalmente alagados, Lagoa Intermitente, Campo com Cambará e Corixo, ocorrem Planossolos de maneira generalizada, o que contribui para a manutenção de níveis temporários mais elevados do lençol freático, devido ao horizonte B plânico com caráter vértico.
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