The past, present and future of vegetation in the Central Atlantic Forest Corridor, Brazil

Future spatial modeling of vegetation in the Central Atlantic Forest Corridor, Brazil

Tropical forests stand out among forest domains, due to their wide diversity of flora and fauna. However, these areas concentrate a large number of the forest fires that occur annually on the planet. In this context, the present study performs spatial modeling of the normalized multi-band drought index (NMDI) in the Central Atlantic Forest Corridor during past (2001-2020) and future (2021-2040) periods to identify the relationship between drought and forest fires. Fire foci data, soil moisture, and data from the MOD09A1 product were used to obtain the NMDI. Rainfall and mean air temperature data from the past and for different future scenarios (SSP126 and SSP585) were also used. The autoregressive integrated moving average model (ARIMA) was used for modeling the NMDI. The results found indicate a recurrence of fire in the CAFC during the period of 2001–2020. Future data indicate reductions in rainfall and an increase in temperature in the CAFC area. The NMDI data indicate that the central region of the corridor is the driest and, among the priority areas for conservation, the Ilha do Lameirão Municipal ecological station has the lowest index values. Future modeling indicates the drought intensifying in the coming years in the corridor area. The CAFC is an extremely important area for the maintenance of Atlantic Forest remnants; however, this area continues to suffer disturbances and without the adoption of public policies, these disturbances could compromise the conservation of natural resources.

Loss of endangered frugivores from seed dispersal networks generates severe mutualism disruption

Many tropical seed-dispersing frugivores are facing extinction, but the consequences of the loss of endangered frugivores for seed dispersal is not well understood. We investigated the role of frugivore endangerment status via robustness-to-coextinction simulations (in this context, more accurately described as robustness-to-partner-loss simulations) using data from the Brazilian Atlantic Forest biodiversity hotspot. By simulating the extinction of endangered frugivores, we found a rapid and disproportionate loss of tree species with dispersal partners in the network, and this surprisingly surpassed any other frugivore extinction scenario, including the loss of the most generalist frugivores first. A key driver of this pattern is that many specialist plants rely on at-risk frugivores as seed-dispersal partners. Moreover, interaction compensation in the absence of endangered frugivores may be unlikely because frugivores with growing populations forage on fewer plant species than frugivores with declining populations. Therefore, protecting endangered frugivores could be critical for maintaining tropical forest seed dispersal, and their loss may have higher-than-expected functional consequences for tropical forests, their regeneration processes, and the maintenance of tropical plant diversity.

Modeling susceptibility to forest fires in the Central Corridor of the Atlantic Forest using the frequency ratio method

Fire is one of the main disturbances of tropical forests. Understanding the spatial and temporal dynamics of forest fires is of fundamental importance for the conservation of tropical forests. We used a frequency ratio model to identify those areas most susceptible to forest fires in the Central Corridor of the Atlantic Forest, from 2001 to 2019. We used data from the burned area of MODIS MCD64A1 to create the dependent variable grouped as climatic, topographic and human and landscape variables. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to assess the model's performance. Land use and relief orientation were the most and least important variables in the model, respectively. The model showed good AUC values, ranging from 0.72 to 0.96, with an average of 0.81 for the study period. The average distribution of susceptibility classes was low (19.62 %), medium (24.45 %) and high (20.55 %). The northwestern region of the CAFC was the one that presented the greatest susceptibility to the occurrence of forest fires. The frequency ratio proved to be a good model for mapping areas susceptible to forest fires in an area of the Atlantic Forest.

Water requirement and growth indicators of forest tree species seedlings produced with automated irrigation management

The lack of information regarding the water requirement of tree species results in water waste in the seedlings production in nurseries. Water requirement, the growth plant factors and water efficiencies for height and diameter were determined for Schizolobium parahyba (Vell.) Blake, Cytharexylum myrianthum Cham. and Ceiba speciosa Ravenna seedlings, under automated irrigation management and greenhouse conditions, located at 22o45'53" S and 43o41'50" W. We used sewage sludge biosolids as substrate in the seedling phase (280 cm-3 tube), and sandy soil material in the initial pot growth phase (18 dm-3 pot). In the seedlings phase, four water replacement levels were applied to the substrate, by drip irrigation, corresponding to average replacement ranging from 40 (V1) to 100% (V4) of the species water requirement. Seedlings developed properly and 80 days after emergence, S. parahyba, C. myrianthum and C. speciosa seedlings received, respectively, 2.40, 1.08 and 0.85 L per plant, for V4. After growth phase (230 DAE), the total water volumes were, respectively, 70.0, 50.3 and 52.7 L per plant. Under adequate water supply, there were rapid recovery and growth of the species, even for the seedlings which showed different height and diameter in the tube phase. The growth plant factors values found were below 0.5 for all species indicating low sensitivity to growth, both in height and in diameter, in response to water deficit. Water efficiency indicators point to distinct trends between the two phases, and C. speciosa has higher values of water efficiencies for height (80.7 and 17.0 cm L-1) and diameter (2.1 and 0.5 mm L-1) in both phases.