Unraveling the genetic diversity of Ceiba pubiflora (Malvaceae) in isolated limestone outcrops: Conservation strategies.

Seasonally Dry Tropical Forests (SDTFs) located on limestone outcrops are vulnerable to degradation caused by timber logging and limestone extraction for cement production. Some of these forests represent the last remnants of native vegetation cover, functioning as isolated islands. Ceiba pubiflora (Malvaceae) is a tree frequently found on limestone outcrops in the central region of Brazil. This study aimed to evaluate the genetic diversity and identify suitable populations for the establishment of Management Units (MUs) for conservation. Inter-simple sequence repeat markers were employed to assess the genetic diversity in ten populations sampled from the Caatinga, Cerrado, and Atlantic Forest biomes. The species exhibited substantial genetic diversity (HT = 0.345; PLP = 97.89%). Populations SAH, JAN, and MON demonstrated elevated rates of polymorphic loci (> 84.2%) along with notable genetic diversity (He > 0.325). Additionally, these populations were the primary contributors to gene flow. The analysis of molecular variance (AMOVA) indicated that most genetic variation occurs within populations (91.5%) than between them. In the Bayesian analysis, the ten populations were clustered into five groups, revealing the presence of at least three barriers to gene flow in the landscape: 1) the Central Plateau or Paranã River valley; 2) near the Espinhaço mountains or the São Francisco River valley; and 3) around the Mantiqueira mountain range, Chapada dos Veadeiros plateau, and disturbed areas. A positive and statistically significant correlation was observed between genetic (θB) and geographic distances (r = 0.425, p = 0.008). Based on these findings, we propose the establishment of Management Units in Minas Gerais state, encompassing the (1) southern region (MIN population), (2) central region (SAH population), and (3) north region (MON population), as well as in Goiás state, covering the (4) Central Plateau region. These units can significantly contribute to preserving the genetic diversity of these trees and protecting their habitat against ongoing threats.

Dissimilar forests along the Rio Doce watershed call for multiple restoration references to avoid biotic homogenization.

An environmental disaster caused by the rupture of a mining tailings dam has impacted a large area of the Rio Doce watershed in the Brazilian Atlantic Forest, resulting in unprecedented damage at spatial and temporal scales. The Atlantic Forest is one of the world's most important biodiversity hotspots. A long history of land use conversion has resulted in a highly fragmented landscape. Despite numerous restoration initiatives, these efforts have often biased criteria and use limited species assemblages. We conducted a comprehensive synthesis of the plant community in riparian forests along the Rio Doce watershed. Our work detailed vegetation composition (tree and sapling strata) and examined its relationship with edaphic and landscape factors, aiming to inform restoration projects with scientifically robust knowledge. A total of 4906 individuals from the tree strata and 4565 individuals from the sapling strata were recorded, representing a total of 1192 species from 75 families. Only 0.8% of the tree species and 0.5% of the sapling species occurred in all sampled sectors, with over 84% of the species occurring in a single watershed sector for both strata. We observed a high species heterogeneity modulated by turnover (92.3% in the tree, and 92.7% in the sapling strata) among sites. Overall, our research revealed a gradient of soil fertility influencing species composition across different strata. Additionally, we discovered that preserved landscapes had a positive impact on species diversity within both strata. The species exclusivity in the sampled sites and the high turnover rate imply the need to consider multiple reference ecosystems when restoring the watershed to reduce the risk of biotic homogenization. Finally, the reference ecosystems defined here serve as a basis for the selection of locally particular species in the implementation of restoration projects that aim to improve biodiversity, ecosystem services, and water security.

Carbon stock and uptake in the high-elevation tropical montane forests of the threatened Atlantic Forest hotspot: Ecosystem function and effects of elevation variation.

Tropical montane forests (TMF) of the threatened Atlantic Forest hotspot play an important role in providing essential ecosystem services associated with hydrological regime and biodiversity conservation. However, important ecological patterns such as those related to the woody carbon biogeochemical cycle are not yet known for these forests, especially those located at high elevations (> 1500 m. a.s.l.). Herein, we used a dataset of 60 plots (2.4 ha) of old-growth TMF sampled along a high-elevation gradient (1500-2100 m a.s.l.) and monitored in two inventories (2011 and 2016) to better understand the patterns of carbon stock and uptake of these high-elevation forests and the related environmental (soil) and elevation controls. We found differences in the carbon stock along different elevation levels (120.36-170.4C.ton.ha-1) and a carbon accumulation trend over the period along the entire gradient. Thus, forest carbon gain (3.82-5.14 ton.ha.year-1) was greater than the carbon loss (2.1-3.4 ton.ha.year-1) and resulted in a positive productivity net. In other words, the TMF acted as a carbon sink, removing carbon from the atmosphere and storing it in woody tissues. Soil variables also exert significant influences on carbon stock and uptake (significative effects of phosphorus on carbon stock and of cation exchange capacity on carbon loss), driving such patterns in isolation or in interaction with elevation. Considering the high conservation degree of the TMF monitored, our results may be indicative of a similar trend in other similar forests, but which have gone through disturbances in the more recent past. These TMF fragments have a wide occurrence in the Atlantic Forest hotspot and may also be acting or will soon act as carbon sinks in improved conservation scenarios. Thus, these forests can play an essential role in conserving ecosystem services in the region and in mitigating climate changes.

Human impacts as the main driver of tropical forest carbon.

Understanding the mechanisms controlling forest carbon storage is crucial to support "nature-based" solutions for climate change mitigation. We used a dataset of 892 Atlantic Forest inventories to assess the direct and indirect effects of environmental conditions, human impacts, tree community proprieties, and sampling methods on tree above-ground carbon stocks. We showed that the widely accepted drivers of carbon stocks, such as climate, soil, topography, and forest fragmentation, have a much smaller role than the forest disturbance history and functional proprieties of the Atlantic Forest. Specifically, within-forest disturbance level was the most important driver, with effect at least 30% higher than any of the environmental conditions individually. Thus, our findings suggest that the conservation of tropical carbon stocks may be dependable on, principally, avoiding forest degradation and that conservation policies focusing only on carbon may fail to protect tropical biodiversity.

Development of microsatellite markers for Calyptranthes clusiifolia (Myrtaceae).

The endemic tree species Calyptranthes clusiifolia (Myrtaceae) plays a relevant ecological role in the forest fragments where it has a common occurrence. In this study, we reported the development of microsatellite markers for C. clusiifolia what will allow a better understanding of the relationship between the forest fragmentation process and the genetic structure and diversity of tree populations. Seven microsatellite markers were developed using an enriched genomic library and characterized in 30 individuals (from three populations). These seven loci were polymorphic and resulted in a total of 23 alleles. The expected heterozygosity (HE) varied from 0.14 (Caly 06) to 0.73 (Caly 22). Linkage disequilibrium between the loci (p > 0.0007) pairs was not detected. The parentage exclusion power of the first (Pe-1) and the second (Pe-2) parents were 0.6099 and 0.8548, respectively. The microsatellite markers developed are indicated for future studies of the genetic diversity in natural populations of C. clusiifolia.

The carbon sink of tropical seasonal forests in southeastern Brazil can be under threat.

Tropical forests have played an important role as a carbon sink over time. However, the carbon dynamics of Brazilian non-Amazon tropical forests are still not well understood. Here, we used data from 32 tropical seasonal forest sites, monitored from 1987 to 2020 (mean site monitoring length, ~15 years) to investigate their long-term trends in carbon stocks and sinks. Our results highlight a long-term decline in the net carbon sink (0.13 Mg C ha-1 year-1) caused by decreasing carbon gains (2.6% by year) and increasing carbon losses (3.4% by year). The driest and warmest sites are experiencing the most severe carbon sink decline and have already moved from carbon sinks to carbon sources. Because of the importance of the terrestrial carbon sink for the global climate, policies are needed to mitigate the emission of greenhouse gases and to restore and protect tropical seasonal forests.

Unveiling neotropical serpentine flora: a list of Brazilian tree species in an iron saturated environment in Bom Sucesso, Minas Gerais

Serpentine soils are those holding at least of 70% iron-magnesium compounds, which make life intolerable for many species. Although plant's adaptation to environmental toughness is widely studied in tropics, virtually nothing is known about Brazilian serpentine flora. Our aim was to bring up and characterize the serpentine flora in Bom Sucesso, Minas Gerais state, Brazil. We performed expeditions utilizing rapid survey sampling method to identify the arboreal compound in the area. Plants within circumference at breast high (CBH) up to 15,7 cm were included in our study. A specialist identified all the individuals to species level. We found 246 species located in 59 botanical families. Fabaceae, Myrtaceae and Melastomataceae were the most representative families in the area. Serpentine areas usually present a few species capable to survive to adverse conditions, contrasting the high number found in our study. To our knowledge, this is the first floristic survey in serpentine areas in the neotropics, reinforcing the need for more studies about plant diversity in those areas. It seems that serpentinites is not the key factor influencing plant diversity in the neotropics. The high diversity found in our study strengthens serpentine areas as a place for conservation concern.

Floristic-structural relationships between Canga ferruginous tree communities and adjacent vegetation types / Relações florístico-estruturais entre comunidades arbóreas de canga ferruginosa e tipos vegetacionais adjacentes

Our objective was to evaluate the floristic and structural relationships between Canga tree communities and other vegetation types inserted in the physiognomic units set, in order to test the hypothesis that these communities have unique characteristics due to their specific environmental conditions. For this, we compared the structural and floristic attributes of Canga vegetation with adjacent semideciduous seasonal forest, Savanna and ecotone areas, evaluating the similarity in its behavior. Our results demonstrate the existence of distinct relationships among vegetation types in relation to different perspectives, related to macro-scale environmental attributes and to the phytogeographic context. In general, Canga tree vegetation has its structure associated with open vegetation types, such as the Cerrado (Savanna) and its composition associated with forest vegetation types, constituted by a community with specific ecological characteristics. Our results suggest the presence of ferruginous soils as a factor that contributes to environmental and ecological heterogeneity in vegetation matrices.

Nosso objetivo foi avaliar as relações florísticas e estruturais entre comunidades arbóreas de Canga e outros tipos vegetacionais inseridos no conjunto de unidades fisionômicas para testar a hipótese de que estas comunidades apresentam características singulares devido às suas condições ambientais especificas. Para isso, comparamos atributos estruturais e florísticos deste tipo vegetacional com outras adjacentes tais como floresta estacional semidecídua, Cerrado e áreas ecotonais, avaliando a similaridade em seu comportamento. Nossos resultados demonstram a existência de relações distintas entres os tipos vegetacionais com relação às diferentes perspectivas, relacionadas à atributos ambientais de macro escala e ao contexto fitogeográfico. No geral, vegetação de canga tem sua estrutura associada a tipos vegetacionais de menor porte como Cerrado e sua composição associada a tipos vegetacionais florestais, consistindo em uma comunidade com características ecológicas específicas. Nossos resultados sugerem a presença de solos ferruginosos como um fator que contribui para a heterogeneidade ambiental e ecológica em matrizes vegetacionais.

Amazon plant diversity revealed by a taxonomically verified species list.

Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests.

Long-term monitoring of diversity and structure of two stands of an Atlantic Tropical Forest.

BACKGROUND: This study aimed to report the long-term monitoring of diversity and structure of the tree community in a protected semideciduous Atlantic Forest in the South of Minas Gerais State, Southeast Brazil. The study was conducted in two stands (B and C), each with 26 and 38 10 m x 30 m plots. Censuses of stand B were conducted in 2000, 2005 and 2011, and stand C in 2001, 2006 and 2011. In both stands, the most abundant and important species for biomass accumulation over the inventories were trees larger than 20 cm of diameter, which characterize advanced successional stage within the forest. NEW INFORMATION: The two surveyed stands within the studied forest presented differences in structure, diversity and species richness over the time.