Ludmila Rattis

Land-use changes have threatened pollinators in tropical forests. Increasing anthropogenic pressures in the Amazon have intensified edge effects and fire frequency, altering environmental filters for forest-adapted groups. Therefore, given their sensitivity to environmental conditions, bee communities may be severely impacted. We assessed how the structure of understory bee community was affected in southeastern Amazon forests under experimental burning 12 years earlier and continuous edge effects, as well as subsequent droughts and blowdowns. Given the bee relationship with habitat quality, we hypothesized that: (i) bee diversity assemblages are smaller in burned forests and edges, (ii) bee species composition would be altered in disturbed forests, and (iii) bee community changes are primarily driven by species loss. We sampled understory bee assemblages using visual and scent traps in an Amazon forest affected by fire and edge effects. Bee diversity was greater in disturbed areas than in undisturbed areas, particularly along burned edges. The bee abundance was not affected by disturbances. Species composition differed among disturbances, with unique species and habitat indicators in each forest area. The changes were driven by species turnover. Implications for insect conservation: After 12 years of regeneration following forest modification by recurrent fires or edge effects, bee assemblages were more diverse. Thus, Amazonian forests, even under multiple disturbances such as repeated fires, severe droughts and blowdown, may still support the persistence or reassembly of different understory bee assemblages. However, changes in bee species composition may indicate potential shifts in the bee community as the forest itself.

Recurrent fires, combined with other disturbances, can severely degrade tropical rainforests. These disturbances alter abiotic conditions such as temperature, moisture and soil organic matter, which may affect termite communities and ecosystem processes. We investigated whether the indirect effects of fire in forests influence termite communities and organic matter decomposition and explored the mechanisms involved. We quantified ecological processes across undisturbed and degraded forests: (1) the relative contributions of invertebrates—particularly termites—and microorganisms to litter decomposition; (2) the relationship between termite abundance and litter decomposition; and (3) the top‐down regulatory effects of ants on termite communities. We took advantage of a long‐term fire experiment in southeastern Amazonia, comprising annually burned, triennially burned and an unburned forest recovering over a decade. Litter decomposition in burned forests was approximately 1.7 times higher than in unburned forest. In burned forests, decomposition was twice as high under invertebrate‐access treatments compared to microbes‐only treatments. In contrast, no difference was observed between invertebrate‐ and microbe‐driven decomposition in unburned forests. These results suggest a more significant role of invertebrates—especially termites—in litter decomposition in degraded forests than in undisturbed ones, while microbial decomposers appear able to compensate for the absence of termites only under undisturbed conditions. Higher litter decomposition was associated with increased termite abundance and reduced ant predation in annually burned plots. These findings suggest that forest degradation is associated with increased termite abundance and activity, potentially accelerating organic matter decomposition and improving soil conditions. Such changes may facilitate forest recovery through cascading effects on nutrient cycling and seedling establishment.

The future of tropical forests depends on their ability to resist and recover from multiple disturbances. Here, we evaluated how edge effects, experimental fires, extreme droughts, and blowdowns reshaped forest structure, composition, and functional traits over two decades in the Amazon–Cerrado transition. Initially, forests resisted low-intensity fires, but subsequent high-intensity fires during severe droughts sharply increased susceptibility to further disturbances. Along forest edges bordering agriculture, these compound disturbances drove losses of tree species richness, declines in Amazonian forest-specialist species, and shifts toward generalists with broad distributions, indicating increased compositional homogenization (i.e., reduced taxonomic diversity and dominance of generalist species). Once fires ceased, recovery trajectories diverged: Interior forests rapidly regained woody species richness and composition, whereas edge forests recovered more slowly. During postfire recovery, embolism-resistant species (lower P50 values) became more common, yet communities exhibited lower hydraulic safety margins (increased vulnerability to drought). At the same time, generalist species remained abundant, forest-specialist declined, and only a single woody species typical of savanna was established. Although grasses initially colonized fire-altered edges—especially light-demanding exotic Andropogon gayanus —they declined once fires stopped, leaving only small patches of shade-tolerant C3 species. Consequently, we find little evidence that fire-degraded forests transition toward persistent savanna, although recurrent fires or future climatic changes could drive long-lasting degradation or human-derived savannas. Together, these results show that even highly degraded, grass-invaded forests can recover in the absence of new disturbances, but the communities that reassemble remain vulnerable to renewed fire, drought, or windthrow.

Brazil emerged as an agricultural powerhouse in the last four decades, producing 33% of the world’s soybeans and 14% of its beef. Historically, much of that growth has come at the expense of its native ecosystems. A growing body of work suggests this paradigm is outdated and brings negative social and environmental outcomes. Here, we provide an integrated analysis of an alternate pathway to solve this puzzle based on a scenario of land-use allocation governance. We compare it with a business-as-usual scenario through the lens of cost, revenues, and impact. The path forward is based on four fronts that can reduce deforestation while increasing production and social well-being. First, allocate undesignated public forests as protected areas and improve the management of new and existing ones. This first strategy would generate a positive return, and foster recognition of human rights, cultural preservation, and improved livelihoods. Second, prevent legal deforestation on private lands and promote compliance with Brazil's Native Vegetation Protection Law (Brasil, 2012) through restoration, also generating positive returns and directing the region towards a zero-deforestation future. Third, promote sustainable intensification of medium and large farms. It would allow Brazil to achieve its agricultural production targets while freeing land up for soy expansion and restoration. Fourth, improve technical assistance and increase market access and income of smallholders while reducing deforestation pressure on family farms. Implementing these fronts requires a coordinated effort between public and private institutions. Still, it would reestablish Brazil`s global leadership in managing natural resources and mitigating climate change.

Forest disturbances associated with edge effects, wildfires, and windthrow events have impacted large swaths of the tropics. Defining the levels of forest disturbance that cause ecologically relevant reductions in fruit and seed (FS) production is key to understanding forest resilience to current and future global changes. Here, we tested the hypotheses that: (1) low‐intensity experimental fires alone would cause minor changes in FS production and diversity in a tropical forest, whereas synergistic disturbance effects resulting from edge effects, wildfires, droughts, and blowdowns would drive long‐term reductions in FS diversity and production; and (2) the functional composition of FS in disturbed forests would shift toward tree species with acquisitive strategies. To test these hypotheses, we quantified FS production between 2005 and 2018 in a large‐scale fire experiment in southeast Amazonia. The experimental treatments consisted of three 50‐ha plots: a Control plot, a plot burned annually (B1yr) and a plot burned every three years (B3yr) between 2004 and 2010. These plots were impacted by edge effects, two droughts (2007 and 2010), and a blowdown event in 2012. Our results show that FS production remained relatively high following low‐intensity fires, but declined where fires were most severe (i.e., forest edge of B3yr). The number of species‐producing FS declined sharply when fires co‐occurred with droughts and a windthrow event, and species composition shifted throughout the experiment. Along the edge of both burned plots, the forest community became dominated by species with faster relative growth, thinner leaves, thinner bark, and lower height. We conclude that compounding disturbances changed FS patterns, with a strong effect on species composition and potentially large effects on the next generation of trees. This is largely due to reductions in the diversity of species‐producing FS where fires are severe, causing a shift toward functional traits typically associated with pioneer and generalist species.

Deforestation and climate change are expected to alter fire regimes along the Cerrado-Amazon transition, one of the world’s most active agricultural frontiers. Here we tested the hypothesis that the time since land-use transition (age of frontier) and agricultural intensification also drive changes in the region’s fire regimes by reducing fire probability in both drought and non-drought years. We modeled fire probability as a function of the time since land-use transitions based on MapBiomas Project datasets from 1986 to 2020. We find that, while burned area declined as pasturelands aged and croplands advanced, deforestation abruptly increased fire activity before (Amazon: 4 years; Cerrado: 3 years) and after (Amazon: 8 years; Cerrado: 7 years) land clearing for pasture, especially in the Amazon. Additionally, the combination of ignition risk, drought, and air-dryness increased the likelihood of large extents of burned areas associated with deforestation. Incorporating frontier age as a proxy for governance in fire modeling is crucial, given the ecological implications of changing fire regimes despite declining rates of fire probability. Most importantly, protecting against deforestation and preserving native vegetation are vital.

Encounters between flowers and invertebrates are key events for the functioning of tropical forests. Assessing the structure of networks composed of the interactions between those partners leads to a better understanding of ecosystem functioning and the effects of environmental factors on ecological processes. Gathering such data is, however, costly and time‐consuming, especially in the highly diverse tropics. We aimed to provide a comprehensive repository of available flower–invertebrate interaction information for the Atlantic Forest, a South American tropical forest domain. Data were obtained from published works and “gray literature,” such as theses and dissertations, as well as self‐reports by co‐authors. The data set has ~18,000 interaction records forming 482 networks, each containing between one and 1061 interaction links. Each network was sampled for about 200 h or less, with few exceptions. A total of 641 plant genera within 136 different families and 39 orders were reported, with the most abundant and rich families being Asteraceae, Fabaceae, and Rubiaceae. Invertebrates interacting with these plants were all arthropods from 10 orders, 129 families, and 581 genera, comprising 2419 morphotypes (including 988 named species). Hymenoptera was the most abundant and diverse order, with at least six times more records than the second‐ranked order (Lepidoptera). The complete data set shows Hymenoptera interacting with all plant orders and also shows Diptera, Lepidoptera, Coleoptera, and Hemiptera to be important nodes. Among plants, Asterales and Fabales had the highest number of interactions. The best sampled environment was forest (~8000 records), followed by pastures and crops. Savanna, grasslands, and urban environments (among others) were also reported, indicating a wide range of approaches dedicated to collecting flower–invertebrate interaction data in the Atlantic Forest domain. Nevertheless, most reported data were from forest understory or lower strata, indicating a knowledge gap about flower–invertebrate interactions at the canopy. Also, access to remote regions remains a limitation, generating sampling bias across the geographical range of the Atlantic Forest. Future studies in these continuous and hard‐to‐access forested areas will yield important new information regarding the interactions between flowers and invertebrates in the Atlantic Forest. There are no copyright restrictions on the data set. Please cite this data paper if the data are used in publications and teaching events.

Tropical fire activity closely follows the co-occurrence of multiple climate stressors. Yet, it remains challenging to quantify how changes in climate alter the likelihood of fire risks associated with compound events. Recent abrupt changes in fire regimes in iconic landscapes in Brazil (namely the Pantanal and Xingu) provide a key opportunity to evaluate how extremely dry and hot conditions, both together and individually, have influenced the probability of large fires. Here we quantify the relationships between climate and fire across these regions and provide evidence on the extent to which fire risk and the associated impacts could be constrained if anthropogenic global warming is limited. We investigate the burned area, differentiating between fire types according to land use (forest fires, savanna fires, farming fires and grassland and wetland fires), and derive present and future fire risks linked to multiple climate variables. We show that concurrent air dryness (high vapour-pressure deficit (VPD)) and low precipitation have driven fire occurrence in both Xingu and the Pantanal, with VPD playing a dominant role. Historical climatic change has already increased compound event-related (CE-related) fire risks of all fire types (5%–10%), and these risks are likely to increase in the future due to global warming. The likelihood of CE-related increase in fire risk may be reduced by up to 14.4% if global warming is constrained to +1.5 °C instead of +3 °C. Nevertheless, substantially increased CE-related fire risks are still expected even if restricting global mean warming to 1.5 °C, particularly in the Pantanal. We thus conclude that climate action should be coordinated with environmental protection to reduce ignition sources and promote effective conservation measures to preserve these biomes.