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Padrões de crescimento em floresta tropical sazonalmente seca em relação à variabilidade ambiental no semiárido pernambucano

Thu, 30 Sep 2021 00:00:00 GMT

Título: Padrões de crescimento em floresta tropical sazonalmente seca em relação à variabilidade ambiental no semiárido pernambucano Autor: COSTA JÚNIOR, Djailson Silva da Primeiro orientador: FERREIRA, Rinaldo Luiz Caraciolo Abstract: This study aims to evaluate the relation of the vegetation to its environmental conditions, in order to understand its behavior, in the seasonally dry tropical forest of Caatinga, in northeastern Brazil. Initially, the annual and monthly variability of rainfall and average air temperature were evaluated and the water deficit was quantified through Climatological Water Balance (CWB). It identified high water deficit, high rainfall variability, an average rainfall of 520.70 mm, and an average annual air temperature of 30.66 ºC. Because of the cyclical drought, there was no soil water surplus in all years studied. The values of potential evapotranspiration of 1563.44 mm.year-1 were higher than the values of precipitation, characteristics of a climate of the type (DdA'a'). Then, the structure, dynamics and growth in basal area of two distinct zones in a Caatinga environment located in Floresta – PE, Brazil were evaluated. They were: A1 (the least preserved), that suffered loss of vegetation in 1986, and A2 (the most preserved), with no substantial history of disturbance. Forty plots (20 m x 20 m) were implanted for the continuous forest inventory – CFI, measuring individual plants with a circumference at 1.30 m from the ground ≥ 6 cm. There was a decrease in the number of families, gender, and species, with mortality rates higher than those of entrances. However, an increase was noticed in the basal area for (A1), initially (2008) with 3.1 m2.ha-1 and in 2019 with a value of 4.6 m2.ha-1. While (A2) came from 8.3 m2.ha-1 to 7.0 m2.ha-1. Thus, a greater influence of drought can be seen on A2, because of a period of low rainfall from 2012 to 2015. Finally, the influence of environmental variables on the periodic annual increment - PAI of the basal area was analyzed using a mixed linear model. Spearman's correlation was used to verify the existence of correlation with environmental variables. The analysis of variance with mixed effects was performed considering period (time) and species as a random effect, while the fixed effects variables were considered as dendrometric: number of shafts, inlets, mortality, equivalent diameter and environmental variables, then the following mixed linear model was created. The mixed ANOVA assumptions were performed based on the analysis of residues. It was noticed that there is a correlation between precipitation and seasonal factor, associated with temperature and drought indices. However, the accumulated annual and semiannual rainfall do not show a strong relationship with the PAI. There was an influence for (A1) in relation to environmental variables in fixed effects parameters, whereas in (A2), only significant influences were noted in the fixed effects for dendrometric variables. In general, the mixed linear model showed good performance for both areas, presenting good residual distributions, without the presence of outliers. It is concluded that vegetation growth is influenced by environmental variables, although this fact was perceived only for A1 (less preserved), for A2 (preserved) such influences were not noted, possibly because of intrinsic individual traits. However, in the long term it is necessary to continue monitoring the vegetation through the studied variables. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese

Padrões e processos ecológicos relacionados à montagem de comunidades no semiárido tropical brasileiro

Tue, 30 Jun 2020 00:00:00 GMT

Título: Padrões e processos ecológicos relacionados à montagem de comunidades no semiárido tropical brasileiro Autor: SILVA, Valdemir Fernando da Primeiro orientador: RODAL, Maria Jesus Nogueira Abstract: Community ecology studies patterns of diversity and processes underlying those patterns. Many studies only consider taxonomic diversity (TD), but the evolutionary history (phylogenetic diversity, PD) and functional traits (functional diversity, FD) of species can also be used to understand the processes that structure diversity patterns, especially taking into account the alpha and beta components of diversity. The use of these approaches allows a better understanding of the relationships between species and the environment since the functional traits of the species can be the result of both the relationship and the species' responses to the environment. Thus, this thesis had the following objectives: (i) test if the variations of the functional traits in the tropical semiarid are responses of the abiotic variables, evolutionary history or by stochastic events and (ii) analyze the congruence between TD, PD and FD different conditions of water and soil availability. In order to answer these objectives, the climatic variables were estimated, the chemical and physical variables of the soil were determined and eight functional traits were measured in 20 areas distributed in a precipitation gradient (502 to 1,423 mmyear-¹) in the semiarid region of northeastern Brazil. Considering aim (i) it was found that there is no influence of the evolutionary history on the variation of the functional traits and that the climatic and soil factors influenced a combination of functional traits that allowed to identify two trade-offs one between leaf area and basic density of branch wood and other leaf area and height. Considering the objective (ii) the three facets of diversity showed different patterns of change in the tropical semiarid. In the alpha component, there was congruence between the different facets of diversity. However, in the beta component in the drier areas, they showed a decrease in taxonomic and functional diversity and an increase in phylogenetic diversity, indicating a pattern of mismatch between these facets of diversity. Different ecological processes drove the communities’ assembly of in the northeastern semiarid, since there were contributions from processes related to the niche and stochastic events. Thus, it is concluded that the variations of the functional traits were responses to the variations of the environment and not to the evolutionary history and that the patterns of assembly of communities in the semiarid differ in the aspects of diversity. The study pointed out that the processes that act to promote the assembly of communities in the tropical semiarid vary with water availability. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese

Variação do gradiente topográfico na diversidade de espécies arbórea-arbustivas em floresta tropical sazonalmente seca

Thu, 27 Feb 2020 00:00:00 GMT

Título: Variação do gradiente topográfico na diversidade de espécies arbórea-arbustivas em floresta tropical sazonalmente seca Autor: SANTOS, José Nailson Barros Primeiro orientador: FELICIANO, Ana Lícia Patriota Abstract: The great edaphic and climatic variability associated with the geomorphological variations of the relief are important factors to promote the floristic and phytophysiognomic variability of the vegetation in the Caatinga. These characteristics are complex, because the levels of aridity depend not only on rainfall patterns, but also on the geological type of the soil, which can guarantee higher levels of nutrients and water storage capacity. Starting from the premise that heterogeneous environments have different resources and abiotic conditions, the present work was developed with the objective of expanding the knowledge of biodiversity and functional strategies displayed by communities of tree-shrub species, associated with a context of topographic gradient in the seasonally dry rainforest. Different biotic properties were sampled, such as vegetation structure, taxonomic diversity (TD), functional diversity (FD) and 10 plant characteristics in three communities in each position of the topographic gradient: depression, slope and plateau, in Chapada do Araripe (state of Pernambuco). Different sets of environmental factors were also determined, which included topographic and edaphoclimatic aspects, and studied their relationship with the characteristics of the vegetation. Different sets of environmental factors were also determined, which included topographic and edaphoclimatic aspects, and studied their relationship with the characteristics of the vegetation. The heterogeneity of edaphoclimatic conditions was essentially predicted by the change in elevation in the Araripe region. The species richness in the Araripe region varied according to the topographic gradient in order of elevation: plateau, slope and depression. The main sets of environmental factors that explained the species richness were attributed to the results of the effects of two sets of variables 'climate-edaphic' (44% of the explication). The diversity of species in the region also coincided with peaks of tree biomass, heterogeneity in the height of the trees, and sometimes with the density of vegetation (NDVI). The elevation alone was able to predict changes in the FD and TD of dominant species, with a positive effect on both. However, the change in TD did not follow the variation in FD, differing in the way they were structured along the topographic gradient. The FD was greater, above all, on the slope, and on the sedimentary plateau than in the depression; while TD was higher in the sedimentary plateau, but did not differ between the slope and depression. The dominance of species characteristics was focused on resource acquisition strategies in depression (> leaves; leaf contente; and > wood density). The effects based on edaphoclimatic factors were tested in isolation, and part of the variation described here suggests that TD was more associated with 'soil-climate' relationships in the topographic gradient, while differences on FD were better related with the variation of the chemical attributes of the soil in the region. Programs to establish new areas of environmental protection must take into account the need to protect a proportion of each of these three levels of the topographic environmental gradient, in order to guarantee greater variability in plant communities, species survival and ecosystem functions. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese

Modelagem de variáveis biofísicas em floresta tropical seca por meio de geotecnologias

Thu, 25 Feb 2021 00:00:00 GMT

Título: Modelagem de variáveis biofísicas em floresta tropical seca por meio de geotecnologias Autor: MOREIRA, Giselle Lemos Primeiro orientador: SILVA, José Antônio Aleixo da Abstract: The forest inventory is an important instrument used to estimate the productive potential of a forest area, however its conventional techniques require time and, in some cases, present difficulties related to access or the size of the area. Thus, the objective of this study was to evaluate the capacity of LiDAR (Light Detection and Ranging) technology and of different orbital sensors in the prediction of biophysical variables volume and dry aboveground biomass (dry AGB) in areas of shrub-tree vegetation in dry tropical forest. To this end, the present work was divided into two chapters with specific objectives. In the first chapter assessed the potential of the metrics derived from the LiDAR ALS (Airborne Laser Scanner) system in predicting volume and dry AGB in dry tropical forest areas. The study was conducted in two areas of Caatinga at Fazenda Itapemirim, located between the municipalities of Floresta and Betânia, in Pernambuco. To assess the potential of LiDAR technology, the multiple linear regression model was adjusted using the ordinary least squares method, where volume and dry AGB stocks, per sample unit, from the forest inventory data carried out in the study areas were used as response variable and as predictive variables used were height LiDAR metrics (position, dispersion and proportion), extracted, per sample unit, from the normalized LiDAR point cloud. From the results found, it was observed that the best equations for the prediction of biophysical variables reached an adjusted coefficient of determination (Adjusted R-squared) of 0.67, with a percentage standard error (SE%) of 20.22% for volume and an Adjusted R-squared of 0.75, with SE% of 14.71% for dry AGB, in addition, it was observed that the equations generated, both in volume and dry AGB, showed tendencies to overestimate lower values and underestimate higher values. Thus, it is concluded that the predictive equations of volume and dry AGB generated through LiDAR technology generated biased values compared to those obtained through the conventional forest inventory. In the second chapter, the potential of the association between metrics derived from LiDAR ALS technology and spectral data from different orbital sensors in the prediction of volume and dry AGB in areas of dry tropical forest was evaluated. To this end, the study was carried out in two fragments of Caatinga at Fazenda Itapemirim, located between the municipalities of Floresta and Betânia, in Pernambuco and data from LiDAR technology and orbital data from the Landsat 8, ResourceSat-2 and RapidEye satellites were used. For the adjustment of the multiple linear regression model, the response variables were the stocks of volume and dry AGB, per sampling unit, derived from the forest inventory data carried out in the study areas and as predictive variables, the LiDAR metrics of height and average values of spectral bands and vegetation indices. It was observed, from the results, that the best equation for volume prediction reached an Adjusted R-squared of 0.80, with SE% of 16.64% and the best equation for dry AGB obtained an Adjusted R-squared of 0.82, with SE% of 10.84%. It was also possible to observe that the generated equations showed tendencies to overestimate lower values and underestimate higher values. In this way, it is concluded that the predictive equations of volume and dry AGB adjusted from the integration between LiDAR ALS data and orbital data were not able to generate results with accuracy compatible with that obtained through the conventional forest inventory, however they presented good precision. In general, it is concluded that the integration of LiDAR ALS metrics and orbital data enabled the generation of more accurate volume and dry AGB estimates when compared to the use of LiDAR ALS data in isolation. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese