Coleções do Repositório
Submissões Recentes
Item type:Publicação, Avaliação da inluência antrópica na diversidade de fungos basidiomycota (agaricomycotina) da reserva florestal Adolfo Ducke(2025-03-03) Ennes, João Fernando Vieira; Souza, João Vicente Braga deMacrofungi diversity is crucial in forest ecosystems, supporting carbon cycling and plant community structure. However, anthropogenic influences threaten this diversity, particularly near urban areas. In Manaus, irregular settlements impact forest fragments, such as the Adolpho Ducke Forest Reserve. This study evaluated the impact of anthropogenic disturbance on Agaricomycotina diversity in preserved and anthropized areas of an Amazonian forest. The study was conducted in two areas: a preserved and an anthropized area both characterized by Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) values. Each area was surveyed over 600 m², divided into six 100 m² plots. Fungal diversity was analyzed using an accumulation curve, morphological and molecular identification (including phylogenetic tree construction and quantification of individuals per taxon), and ecological indices (Shannon-Weaver, Sørensen, and evenness). Twenty-five taxa were recorded in the preserved area, with Marasmius spp., Mycena spp., Amauroderma spp., Auricularia spp., and Schizophyllum spp. being the most frequent genera. In the anthropized area, six taxa were recorded, with Trametes spp., Schizophyllum sp., Marasmius spp., Pycnoporus sp., and Auricularia sp. being the most frequent. Statistical analysis revealed higher diversity in the preserved region (H’ = 3.17 ± 0.09) and lower evenness (E = 0.76 ± 0.12), while the anthropized area showed lower diversity (H’ = 2.01 ± 0.12) and higher evenness (E = 0.79 ± 0.18). Results show a significant reduction in fungal diversity in anthropized areas, highlighting the negative impact of human intervention on biodiversity.Item type:Publicação, Respostas ecofisiológicas de plantas de sub-bosque ao aumento de CO₂ atmosférico e à seca intensificada pelo El Niño em uma floresta de terra firme na Amazônia Central(2025) Soares, José Carlos Rodrigues; Aleixo, Izabela Fonseca; Garcia, Sabrina; Quesada, Carlos Alberto NobrePhysiological and ecological processes, as well as the resilience and productivity of the Amazon Rainforest, can be profoundly affected by global environmental and climate changes. Among these factors, the increase in atmospheric carbon dioxide (CO₂) concentration and alterations in hydrological regimes stand out, especially the reduction in precipitation associated with the intensification of droughts caused by extreme events such as the El Niño–Southern Oscillation (ENSO), which are becoming increasingly frequent and severe in the Amazon basin. However, the responses of tropical forests to the combination of these factors are still not fully understood. In order to contribute to filling these gaps and improving the understanding of in situ plant responses to elevated CO₂ (eCO₂) and drought, this thesis aimed to investigate the effects of eCO₂ and drought intensified by El Niño on understory plants in a terra firme forest in Central Amazonia. To achieve this objective, we conducted a pioneering experiment using Open-Top Chambers (OTCs) to simulate future scenarios of elevated CO₂ concentration, with four chambers maintained under ambient conditions (control) and another four exposed to elevated CO₂ (treatment), with an increase of 250 ppmv relative to ambient levels. Measurements took place during the 2023 dry season, intensified by El Niño, and in the subsequent 2024 wet season. This climatic context provided a unique opportunity to investigate, under in situ conditions, the combined effects of eCO₂ and drought on the ecophysiological performance of understory plants. During the drought, there was a reduction in the photosynthetic efficiency of the plants, and traits related to growth appear to modulate the response to water stress (Chapter 1). Plants activate protective mechanisms to mitigate the effects of drought on photosystem II, promoting the reallocation of energy among utilization and dissipation pathways (Chapter 2). Additionally, eCO₂ may attenuate the negative effects of drought on understory plants. These results are relevant because they demonstrate how tropical species adjust physiological traits when faced with the combination of complex factors. Understanding these mechanisms provides support for predicting ecosystem responses and functionality in the Amazon as extreme drought events intensify and atmospheric eCO₂ levels continue to increase.Item type:Publicação, O papel da fenologia foliar sobre a dinâmica da estrutura populacional e etária de folhas no dossel superior de uma floresta de terra firme na Amazônia Central(2022-11-30) Assis, Pedro Ivo Lembo Silveira de; Manzi, Antonio Ocimar; Martins, Giordane AugustoLeaf phenology impacts carbon, water, and nutrient cycles from local to global scales. In the Amazon forest, massive events of leaf flushing and abscission promote a seasonal shift in the age composition of upper-canopy leaves. A demographic and ontogenetic model suggests that this shift is the main trigger of the seasonality of photosynthetic capacity (PC) in Terra Firme forests in central Amazonia. However, the method (phenocams) from which data are collected and used to feed the model present limitations that enable to realize percentage of leaf turnover in evergreen tree crowns and the mean age of leaves discarded annually, thus generating uncertainties regarding the proportion of new, mature, and old leaves in the upper canopy. Leaf age dynamics emerge from trees with different habits and leaf phenological strategies. Therefore, investigating the temporal behavior of leaf dynamics in the upper-canopy tree community is necessary to understand age dynamics at the ecosystem scale. Monthly assessment (November/2015 to November/2019) of the components of leaf dynamics (leaf storage, leaf flush, and leaf fall) was conducted on branches, totaling 330, equally distributed among 33 trees at upper canopy Terra Firme forest on a plateau in central Amazonia (ATTO site). Information regarding leaf age was obtained only for those leaves for which the flushing event was observed. Similarly, leaf longevity data were extracted only for leaves for which both flushing and death events were necessarily observed throughout the study. Three phenological behaviors were identified: evergreen (29), annually brevi-deciduous (1), and biennially brevi-deciduous (3), which appear to be associated with distinct strategy of resource use and management, such as water and carbon. Evergreen canopies exhibit a complex age structure, with high variability in leaf longevity (1 to 43 months), revealing information that is hidden from phenological cameras. In contrast, leaf longevity close to and concentrated around 12 and 24 months was reported for annually and biennially brevi-deciduous trees, respectively. Leaf dynamics sampled on branches proved to be representative of the ecosystem. The number of leaves in the upper canopy does not appear to be seasonal, although annual events of massive leaf exchange by the tree community during dry months significantly alter the age composition of upper-canopy leaves. This composition is diverse and complex, shaped by individual trees with distinct leaf habits and phenological strategies. Annual canopy turnover appears to occur partially (50%), as a result of a mean leaf longevity longer than one year (≈ 20.1 months), and therefore half of the canopy population is composed of leaves that survive beyond an annual leaf phenology cycle. The empirical evidence presented here sheds new light on the understanding of leaf longevity in the upper canopy and the pattern of seasonal canopy turnover, aspects that remain poorly represented or absent in current models.Item type:Pessoa, Item type:Pessoa,