Metal nanoparticles and pesticides under global climate change: Assessing the combined effects of multiple abiotic stressors on soil microbial ecosystems.

The soil is a vital resource that hosts many microorganisms crucial in biogeochemical cycles and ecosystem health. However, human activities such as the use of metal nanoparticles (MNPs), pesticides and the impacts of global climate change (GCCh) can significantly affect soil microbial communities (SMC). For many years, pesticides and, more recently, nanoparticles have contributed to sustainable agriculture to ensure continuous food production to sustain the significant growth of the world population and, therefore, the demand for food. Pesticides have a recognized pest control capacity. On the other hand, nanoparticles have demonstrated a high ability to improve water and nutrient retention, promote plant growth, and control pests. However, it has been reported that their accumulation in agricultural soils can also adversely affect the environment and soil microbial health. In addition, climate change, with its variations in temperature and extreme water conditions, can lead to drought and increased soil salinity, modifying both soil conditions and the composition and function of microbial communities. Abiotic stressors can interact and synergistically or additively affect soil microorganisms, significantly impacting soil functioning and the capacity to provide ecosystem services. Therefore, this work reviewed the current scientific literature to understand how multiple stressors interact and affect the SMC. In addition, the importance of molecular tools such as metagenomics, metatranscriptomics, proteomics, or metabolomics in the study of the responses of SMC to exposure to multiple abiotic stressors was examined. Future research directions were also proposed, focusing on exploring the complex interactions between stressors and their long-term effects and developing strategies for sustainable soil management. These efforts will contribute to the preservation of soil health and the promotion of sustainable agricultural practices.

Marine Heatwave Caused Differentiated Dysbiosis in Photosymbiont Assemblages of Corals and Hydrocorals During El Niño 2015/2016.

Reef corals have been threatened by climate change, with more frequent and intense bleaching events leading to extensive coral mortality and loss of coral cover worldwide. In the face of this, the corals' photosymbiont assemblages have received special attention as a key to better understand the bleaching process and its recovery. To assess the effects of thermal anomalies, the coral Mussismilia harttii and the hydrocoral Millepora alcicornis were monitored through the El Niño 2015/2016 at a Southwestern Atlantic (SWA) coral reef. A severe bleaching event (57% of colonies bleached) was documented, triggered by a < 3 °C-week heatwave, but no mortality was detected. The hydrocoral was more susceptible than the scleractinian, displaying bleaching symptoms earlier and experiencing a longer and more intense bleaching event. The composition of photosymbionts in the M. alcicornis population was affected only at the rare biosphere level (< 5% relative abundance), with the emergence of new symbionts after bleaching. Conversely, a temporary dysbiosis was observed in the M. harttii population, with one of the dominant symbiodiniaceans decreasing in relative abundance at the peak of the bleaching, which negatively affected the total ß-diversity. After colonies' complete recovery, symbiodiniaceans' dominances returned to normal levels in both hosts. These results highlight critical differences in how the two coral species cope with bleaching and contribute to the understanding of the role of photosymbionts throughout the bleaching-recovery process.

Management of Rhizosphere Microbiota and Plant Production under Drought Stress: A Comprehensive Review.

Drought generates a complex scenario worldwide in which agriculture should urgently be reframed from an integrative point of view. It includes the search for new water resources and the use of tolerant crops and genotypes, improved irrigation systems, and other less explored alternatives that are very important, such as biotechnological tools that may increase the water use efficiency. Currently, a large body of evidence highlights the role of specific strains in the main microbial rhizosphere groups (arbuscular mycorrhizal fungi, yeasts, and bacteria) on increasing the drought tolerance of their host plants through diverse plant growth-promoting (PGP) characteristics. With this background, it is possible to suggest that the joint use of distinct PGP microbes could produce positive interactions or additive beneficial effects on their host plants if their co-inoculation does not generate antagonistic responses. To date, such effects have only been partially analyzed by using single omics tools, such as genomics, metabolomics, or proteomics. However, there is a gap of information in the use of multi-omics approaches to detect interactions between PGP and host plants. This approach must be the next scale-jump in the study of the interaction of soil-plant-microorganism. In this review, we analyzed the constraints posed by drought in the framework of an increasing global demand for plant production, integrating the important role played by the rhizosphere biota as a PGP agent. Using multi-omics approaches to understand in depth the processes that occur in plants in the presence of microorganisms can allow us to modulate their combined use and drive it to increase crop yields, improving production processes to attend the growing global demand for food.

Bird rookery nutrient over-enrichment as a potential accelerant of mangrove cay decline in Belize.

Coastal eutrophication is an issue of serious global concern and although nutrient subsidies can enhance primary productivity of coastal wetlands, they can be detrimental to their long-term maintenance. By supplying nutrients to coastal ecosystems at levels comparable to intensive agriculture practices, roosting colonial waterbirds provide a natural experimental design to examine the impacts of anthropogenic nutrient enrichment in these systems. We tested the hypothesis that long-term nutrient enrichment from bird guano deposition is linked to declines in island size, which may subsequently decrease the stability and resilience of mangrove cays in Belize. We combined remote sensing analysis with field- and lab-based measurements of forest structure, sediment nutrients, and porewater nutrients on three pairs of rookery and control cays in northern, central, and southern Belize. Our results indicate that rookery cays are disappearing approximately 13 times faster than cays without seasonal or resident seabird populations. Rookery cays were associated with a significantly higher concentration of nitrogen (N) in mangrove leaves and greater aboveground biomass, suggesting that eutrophication from bird guano contributes to increased aboveground productivity. Sediments of rookery cays also had lower percentages of soil organic matter and total N and carbon (C) than control islands, which suggests that eutrophication accelerates organic matter decomposition resulting in lower total C stocks on rookery cays. Our results indicate that coastal eutrophication can reduce ecosystem stability by contributing to accelerated cay loss, with potential consequences for mangrove resilience to environmental variability under contemporary and future climatic scenarios.

Disentangling the trend in the warming of urban areas into global and local factors.

Large cities account for a significant share of national population and wealth, and exert high pressure on local and regional resources, exacerbating socioenvironmental risks. The replacement of natural landscapes with higher heat capacity materials because of urbanization and anthropogenic waste heat are some of the factors contributing to local climate change caused by the urban heat island (UHI) effect. Because of synergistic effects, local climate change can exacerbate the impacts of global warming in cities. Disentangling the contributions to warming in cities from global and local drivers can help to understand their relative importance and guide local adaptation policies. The canopy UHI intensity is commonly approximated by the difference between temperatures within cities and the surrounding areas. We present a complementary approach that applies the concept of common trends to extract the global contributions to observed warming in cities and to obtain a residual warming trend caused by local and regional factors. Once the effects of global drivers are removed, common features appear in cities' temperatures in the eastern part of the United States. Most cities experienced higher warming than that attributable to global climate change, and some shared a period of rapid warming during urban sprawl in the mid-20th century in the United States.

Effect of ultraviolet radiation on the metabolomic profiles of potentially toxic cyanobacteria.

Interactions between climate change and ultraviolet radiation (UVR) have a substantial impact on aquatic ecosystems, especially on photosynthetic organisms. To counteract the damaging effects of UVR, cyanobacteria developed adaptive strategies such as the biosynthesis of secondary metabolites. This study aimed to evaluate the effects of UVR on the metabolomic profiles of potentially toxic cyanobacteria. Twelve strains were irradiated with ultraviolet A and ultraviolet B radiation and parabolic aluminized reflector lamps for 3 days, followed by liquid chromatography-tandem mass spectometry (LC-MS/MS) analysis to assess changes in metabolomic profiles. Matrices were used to generate principal component analysis biplots, and molecular networks were obtained using the Global Natural Products platform. Most strains showed significant changes in their metabolomic profiles after UVR exposure. On average, 7% of MS features were shown to be exclusive to metabolomic profiles before UVR exposure, while 9% were unique to metabolomic profiles after UVR exposure. The identified compounds included aeruginosins, spumigins, cyanopeptolins, microginins, namalides, pseudospumigins, anabaenopeptins, mycosporine-like amino acids, nodularins and microcystins. Data showed that cyanobacteria display broad metabolic plasticity upon UVR exposure, including the synthesis and differential expression of a variety of secondary metabolites. This could result in a competitive advantage, supporting cyanobacterial blooms under various UVR light exposures.

Temperature and altitude modulate feeding attributes of Mexican beetle, Zygogramma bicolorata Pallister on Parthenium hysterophorus.

Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) is an effective biocontrol agent of Parthenium hysterophorus L. which is an alien invasive herbaceous weed with a pan-tropical distribution. The present study aimed to assess the effects of temperature and altitude on feeding attributes (consumption rate, conversion efficiency and growth rate) of adults from the wild populations of Z. bicolorata inhabiting India and Nepal. Results revealed that adults inhabiting areas of low temperature (24°C ‒ 25°C) and high altitude (415 m ‒1400 m) were large and had higher food consumption rates. In contrast, those inhabiting areas of high temperature (34°C ‒ 36°C) and low altitude (81 m ‒ 229 m) were smaller and had higher food utilization efficiencies. In all the eco-climatic regions, females were larger than males and had higher feeding attributes than their counterparts. Temperature between 27°C and 30°C was found optimal for Z. bicolorata adults to convert and utilize the food biomass to body mass. Above the optimal temperature the feeding attributes decreased. Present results suggest that there exists a possibility for decrease in body size, and thereby weed biocontrol efficiency of Z. bicolorata adults with an increase in temperature due to global climate change.

Combined effect of pCO2 and temperature levels on the thermal niche in the early benthic ontogeny of a keystone species.

We evaluated the effects of projected, near future ocean acidification (OA) and extreme events of temperature (warming or cooling) on the thermal tolerance of Concholepas concholepas, a coastal benthic keystone species. Three separate trials of an experiment were conducted by exposing juvenile C. concholepas for 1 month to one of two contrasting pCO2 levels (~500 and ~1200 µatm). In addition, each pCO2 level was combined with one of four temperature treatments. The control was 15 °C, whilst the other temperatures were 10 °C (Trial 1), 20 °C (Trial 2) and 25 °C (Trial 3). At the end of each trial, we assessed Critical Thermal maximum (CTmax) and minimum (CTmin) via self-righting success, calculated partial thermal tolerance polygons, measured somatic growth, determined transcription of Heat Shock Proteins 70 (HSP70) and measured oxygen consumption rates. Regardless of pCO2 level, HSP70 transcript levels were significantly higher in juveniles after exposure to extreme temperatures (10 °C and 25 °C) indicating physiological stress. Oxygen consumption rates increased with increasing temperature from 10 °C to 20 °C though showed a decrease at 25 °C. This rate was not affected by pCO2 or the interaction between temperature and pCO2. Juveniles exposed to present-day and near future pCO2 levels at 20 °C showed similar thermal tolerance polygonal areas; whilst changes in both CTmin and CTmax at 25 °C and 10 °C caused narrower and broader areas, respectively. Temperature affected growth, oxygen consumption and HSP70 transcription in small juvenile C. concholepas. Exposure to elevated pCO2 did not affect thermal tolerance, growth or oxygen consumption at temperatures within the thermal range normally experienced by this species in northern Chile (15-20 °C). At elevated pCO2 conditions, however, exposure to warmer (25 °C) or colder (10 °C) temperatures reduced or increased the thermal area, respectively. This study demonstrates the importance of examining the thermal-tolerance edges to better understand how OA and temperature will combine to physiologically challenge inter-tidal organisms.

Molecular bases of responses to abiotic stress in trees.

Trees are constantly exposed to climate fluctuations, which vary with both time and geographic location. Environmental changes that are outside of the physiological favorable range usually negatively affect plant performance and trigger responses to abiotic stress. Long-living trees in particular have evolved a wide spectrum of molecular mechanisms to coordinate growth and development under stressful conditions, thus minimizing fitness costs. The ongoing development of techniques directed at quantifying abiotic stress has significantly increased our knowledge of physiological responses in woody plants. However, it is only within recent years that advances in next-generation sequencing and biochemical approaches have enabled us to begin to understand the complexity of the molecular systems that underlie these responses. Here, we review recent progress in our understanding of the molecular bases of drought and temperature stresses in trees, with a focus on functional, transcriptomic, epigenetic, and population genomic studies. In addition, we highlight topics that will contribute to progress in our understanding of the plastic and adaptive responses of woody plants to drought and temperature in a context of global climate change.

Stomatal Development and Conductance of a Tropical Forage Legume Are Regulated by Elevated [CO2] Under Moderate Warming.

The opening and closing of stomata are controlled by the integration of environmental and endogenous signals. Here, we show the effects of combining elevated atmospheric carbon dioxide concentration (eCO 2; 600 µmol mol-1) and warming (+2°C) on stomatal properties and their consequence to plant function in a Stylosanthes capitata Vogel (C3) tropical pasture. The eCO 2 treatment alone reduced stomatal density, stomatal index, and stomatal conductance (gs ), resulting in reduced transpiration, increased leaf temperature, and leading to maintenance of soil moisture during the growing season. Increased CO2 concentration inside leaves stimulated photosynthesis, starch content levels, water use efficiency, and PSII photochemistry. Under warming, plants developed leaves with smaller stomata on both leaf surfaces; however, we did not see effects of warming on stomatal conductance, transpiration, or leaf water status. Warming alone enhanced PSII photochemistry and photosynthesis, and likely starch exports from chloroplasts. Under the combination of warming and eCO 2, leaf temperature was higher than that of leaves from the warming or eCO 2 treatments. Thus, warming counterbalanced the effects of CO2 on transpiration and soil water content but not on stomatal functioning, which was independent of temperature treatment. Under warming, and in combination with eCO 2, leaves also produced more carotenoids and a more efficient heat and fluorescence dissipation. Our combined results suggest that control on stomatal opening under eCO 2 was not changed by a warmer environment; however, their combination significantly improved whole-plant functioning.

Vineyards in transition: A global assessment of the adaptation needs of grape producing regions under climate change.

This paper suggests how climate change may transform vineyards. We consider changes in agro-climatic indicators derived from climatic variables as drivers for adaptation needs. We use two climate scenarios, GCM GFL-ESM2M and HadGEM2-ES, with 0.5° spatial resolution and daily time step forced by two emission scenarios, RCP2.6 and 6.0, to estimate the transition of potential vineyards in the major grape production world areas by the late 21st century. We present and discuss changes in three impact indicators - one drought indicator and two temperature ones - aimed at exploring the benefits of transition-based policies. The drought indicator provides insights to prepare adaptation for extreme events in probabilistic terms. The temperature indicators offer information on the transition towards suitable zones of production. Future projections suggest a lack of water to maintain current levels of production in all regions of the world. Furthermore, thermal suitability of grapevine may be greatly affected in China and the Mediterranean region. Nevertheless, the possibility of quality wines is not altered within the regions with adequate suitability. Lastly, a portfolio of strategies to adapt to the future climate is presented.

Elevated CO2 concentration improves functional traits and early growth of the widespread species Enterolobium contortisiliquum (Vell. ) Morong / Elevada concentração de CO2 melhora as características funcionais e o crescimento inicial da espécie generalista Enterolobium contortisiliquum (Vell. ) Morong

Enterolobium contortisiliquum is a neotropical widespread species that occurs in native AtlanticForest, Cerrado and Caatinga vegetation in Brazil. Outside Brazil, it occurs in Argentina, Bolivia, Paraguay, and Uruguay. The objective of this study was to investigate the influence of high carbon dioxide concentration [CO2] on leaf gas exchange, chlorophyll content, chlorophyll a fluorescence, growth, and biomass allocation among roots, stems, and leaves in young plants of E. contortisiliquum. After germination, twenty days old individuals of E. contortisiliquum were grown in open-top chambers (OTC) at two different [CO2] (400 ppm and 700 ppm). Physiological measurements were made when the plants had been grown in OTC for 170, 200, 230, and 260 days. The higher [CO2] favored the early growth of E. contortisiliquum by increasing maximum net photosynthesis (PN) and water use efficiency. Under high [CO2], root dry mass increased in E. contortisiliquum, which might be a trait that will benefit this species by enhancing water uptake, particularly in seasonally dry environments.(AU)

Enterolobium contortisiliquum é uma espécie neotropical generalista, encontrada na vegetação nativa da Mata Atlântica do Brasil, no Cerrado e na Caatinga. Fora do país, também pode ser encontrada empaíses como Argentina, Bolívia, Paraguai e Uruguai. O objetivo deste estudo foi investigar a influência da alta concentração de dióxido de carbono [CO2] nas trocas gasosas foliares, no teor de clorofila, na fluorescência da clorofila a, no crescimento e alocação de biomassa entre raízes, caules e folhas em plantas jovens de E. contortisiliquum. Após a germinação, indivíduos de E. contortisiliquum de 20 dias de idade foram cultivados em câmaras de topo aberto (CTA), em duas diferentes [CO2] (400 ppm e 700 ppm). Asmedições fisiológicas foram realizadas no momento do cultivo das plantas em CTA por 170, 200, 230 e 260 dias. A alta [CO2] favoreceu o crescimento inicial de E. contortisiliquum aumentando a fotossíntese líquida máxima (PN) e a eficiência do uso da água. Sob alta [CO2], a massa seca da raiz aumentou em E. contortisiliquum, o que pode ser uma característica que beneficiará esta espécie, aumentando a absorção de água, particularmente em ambientes sazonalmente secos.(AU)

Fish thermal habitat current use and simulation of thermal habitat availability in lakes of the Argentine Patagonian Andes under climate change scenarios RCP 4.5 and RCP 8.5.

Habitat use in relation to the thermal habitat availability and food source as a forcing factor on habitat selection and use of Percichthys trucha (Creole perch), Oncorhynchus mykiss (rainbow trout), Salmo trutta (brown trout) and Salvelinus fontinalis (brook trout) were determined as well as future potential thermal habitat availability for these species under climate change scenarios Representative Concentration Pathways 4.5 and 8.5. This study was conducted in three interconnected lakes of Northern Patagonia (Moreno Lake system). Data on fish abundance was obtained through gill netting and hydroacoustics, and thermal profiles and fish thermal habitat suitability index curves were used to identify current species-specific thermal habitat use. Surface air temperatures from the (NEX GDDP) database for RCP scenarios 4.5 and 8.5 were used to model monthly average temperatures of the water column up to the year 2099 for all three lakes, and to determine potential future habitat availability. In addition, data on fish diet were used to determine whether food could act as a forcing factor in current habitat selection. The four species examined do not use all the thermally suitable habitats currently available to them in the three lakes, and higher fish densities are not necessarily constrained to their "fundamental thermal niches" sensu Magnuson et al. (1979), as extensive use is made of less suitable habitats. This is apparently brought about by food availability acting as a major forcing factor in habitat selection and use. Uncertainties related to the multidimensionality inherent to habitat selection and climate change imply that fish resource management in Patagonia will not be feasible through traditional incremental policies and strategic adjustments based on short-term predictions, but will have to become highly opportunistic and adaptive.

Elevated CO2 concentration improves functional traits and early growth of the widespread species Enterolobium contortisiliquum (Vell. ) Morong / Elevada concentração de CO2 melhora as características funcionais e o crescimento inicial da espécie generalista Enterolobium contortisiliquum (Vell. ) Morong

Enterolobium contortisiliquum is a neotropical widespread species that occurs in native AtlanticForest, Cerrado and Caatinga vegetation in Brazil. Outside Brazil, it occurs in Argentina, Bolivia, Paraguay, and Uruguay. The objective of this study was to investigate the influence of high carbon dioxide concentration [CO2] on leaf gas exchange, chlorophyll content, chlorophyll a fluorescence, growth, and biomass allocation among roots, stems, and leaves in young plants of E. contortisiliquum. After germination, twenty days old individuals of E. contortisiliquum were grown in open-top chambers (OTC) at two different [CO2] (400 ppm and 700 ppm). Physiological measurements were made when the plants had been grown in OTC for 170, 200, 230, and 260 days. The higher [CO2] favored the early growth of E. contortisiliquum by increasing maximum net photosynthesis (PN) and water use efficiency. Under high [CO2], root dry mass increased in E. contortisiliquum, which might be a trait that will benefit this species by enhancing water uptake, particularly in seasonally dry environments.

Enterolobium contortisiliquum é uma espécie neotropical generalista, encontrada na vegetação nativa da Mata Atlântica do Brasil, no Cerrado e na Caatinga. Fora do país, também pode ser encontrada empaíses como Argentina, Bolívia, Paraguai e Uruguai. O objetivo deste estudo foi investigar a influência da alta concentração de dióxido de carbono [CO2] nas trocas gasosas foliares, no teor de clorofila, na fluorescência da clorofila a, no crescimento e alocação de biomassa entre raízes, caules e folhas em plantas jovens de E. contortisiliquum. Após a germinação, indivíduos de E. contortisiliquum de 20 dias de idade foram cultivados em câmaras de topo aberto (CTA), em duas diferentes [CO2] (400 ppm e 700 ppm). Asmedições fisiológicas foram realizadas no momento do cultivo das plantas em CTA por 170, 200, 230 e 260 dias. A alta [CO2] favoreceu o crescimento inicial de E. contortisiliquum aumentando a fotossíntese líquida máxima (PN) e a eficiência do uso da água. Sob alta [CO2], a massa seca da raiz aumentou em E. contortisiliquum, o que pode ser uma característica que beneficiará esta espécie, aumentando a absorção de água, particularmente em ambientes sazonalmente secos.

Mudanças climáticas globais: viés de percepção, tempo e espaço / Global climate changes: Perception bias, time and space / Cambio climático global: Sesgo de percepción, tiempo y espacio

Investigamos a percepção das mudanças climáticas globais e de sua gravidade em relação às escalas espacial e temporal. Colaboraram 52 estudantes, de ensino médio e superior, sendo 17 do sexo feminino e 35 do masculino. Utilizamos um questionário com perguntas tanto abertas como de múltipla escolha. Detectamos paralelos com o viés de otimismo espacial reportado na literatura, ou seja, uma visão mais positiva da situação quando se trata de ambientes geograficamente mais próximos do respondente. Esse otimismo também foi claramente identificado na escala temporal do momento presente. Para temporalidades maiores (10, 25, ou mais anos no futuro), as tendências observadas não foram tão claras, mas sugerem um otimismo temporal, e não o pessimismo temporal ("as coisas vão piorar") encontrado em estudos anteriores. Esses achados podem nortear projetos de educação ambiental que enfoquem o âmbito local e condições de existência no mesmo, indo além da avaliação positiva costumeiramente identificada na literatura (AU).

Global climate changes: Perception bias, time and space. We investigated the perception of global climate changes (GCCs) and their severity in relation to spatial and temporal scales. Participants were 52 students of secondary and higher education, being 17 females and 35 males. We employed a questionnaire containing open- ended and multiple-choice issues. We detected parallels with the bias of spatial optimism reported in the literature, that is, a more positive assessment of the situation for environments geographically closer to the respondent. This optimism was also clearly identified in the time scale of the present moment. For major temporalities (10, 25, or more years in the future), the trends observed were not so clear, but suggest a temporal optimism, not the temporal pessimism ("things will get worse") found in previous studies. These findings can guide environmental education projects that focus on the local scope and conditions of existence in the same, going beyond the positive evaluation customarily identified in the literature (AU).

Cambio climático global: Sesgo de percepción, tiempo y espacio. Investigamos la percepción de los cambios climáticos globales (CCGs) y de su gravedad con relación a las escalas espacial y temporal. Colaboraran 52 estudiantes, de enseñanza media y superior, siendo 17 del sexo femenino e 35 del masculino. Utilizamos un cuestionario con preguntas abiertas y de elección múltiple. Detectamos paralelos con el sesgo de optimismo espacial mencionado en la literatura, o sea, una visión más positiva de la situación cuando se trata de ambientes geográficamente más cercanos del respondiente. Ese optimismo también fue claramente identificado en la escala temporal del momento presente. Para temporalidades mayores (10, 25, o más años en el futuro), las tendencias observadas no fueran tan claras, pero sugieren un optimismo temporal, y no el pesimismo temporal ("las cosas van a empeorar") encontrado en estudios anteriores. Estos hallazgos pueden orientar proyectos de educación ambiental que enfoquen el ámbito local y condiciones de existencia en el mismo, yendo más allá de la evaluación positiva habitualmente identificada en la literatura (AU).

First Assessment of Carbon Stock in the Belowground Biomass of Brazilian Mangroves

ABSTRACT Studies on belowground roots biomass have increasingly reported the importance of the contribution of this compartment in carbon stock maintenance in mangrove forests. To date, there are no estimates of this contribution in Brazilian mangrove forests, although the country has the second largest area of mangroves worldwide. For this study, trenches dug in fringing forests in Guaratiba State Biological Reserve (Rio de Janeiro, Brazil) were used to evaluate the contribution of the different classes of roots and the vertical stratification of carbon stock. The total carbon stock average in belowground roots biomass in these forests was 104.41 ± 20.73 tC.ha−1. From that, an average of 84.13 ± 21.34 tC.ha−1 corresponded to the carbon stock only in fine roots, which have diameters smaller than 5 mm and are responsible for over 80% of the total belowground biomass. Most of the belowground carbon stock is concentrated in the first 40 cm below the surface (about 70%). The root:shoot ratio in this study is 1.14. These estimates demonstrate that the belowground roots biomass significantly contributes, more than 50%, to the carbon stock in mangrove forests. And the mangrove root biomass can be greater than that of other Brazilian ecosystems.

Comment (2) on "Formation of the Isthmus of Panama" by O'Dea et al.

O'Dea et al. challenged the inference that the Isthmus of Panama has been in place for the last 10 million years or more and from "an exhaustive review and reanalysis of geological, paleontological, and molecular records," they argued for a "formation of the Isthmus of Panama sensu stricto around 2.8 Ma." I review environmental changes since ~5 Ma throughout Earth, and I argue that environmental changes in the Central American-Caribbean region have been part of a concurrent, worldwide phenomenon that requires a global, not local, explanation. Accordingly, evidence of environmental change from the Central American-Caribbean region does not implicate the emergence of the Isthmus of Panama.

Response of the endangered tropical dry forests to climate change and the role of Mexican Protected Areas for their conservation.

Assuming that co-distributed species are exposed to similar environmental conditions, ecological niche models (ENMs) of bird and plant species inhabiting tropical dry forests (TDFs) in Mexico were developed to evaluate future projections of their distribution for the years 2050 and 2070. We used ENM-based predictions and climatic data for two Global Climate Models, considering two Representative Concentration Pathway scenarios (RCP4.5/RCP8.5). We also evaluated the effects of habitat loss and the importance of the Mexican system of protected areas (PAs) on the projected models for a more detailed prediction of TDFs and to identify hot spots that require conservation actions. We identified four major distributional areas: the main one located along the Pacific Coast (from Sonora to Chiapas, including the Cape and Bajío regions, and the Balsas river basin), and three isolated areas: the Yucatán peninsula, central Veracruz, and southern Tamaulipas. When considering the effect of habitat loss, a significant reduction (~61%) of the TDFs predicted area occurred, whereas climate-change models suggested (in comparison with the present distribution model) an increase in area of 3.0-10.0% and 3.0-9.0% for 2050 and 2070, respectively. In future scenarios, TDFs will occupy areas above its current average elevational distribution that are outside of its present geographical range. Our findings show that TDFs may persist in Mexican territory until the middle of the XXI century; however, the challenges about long-term conservation are partially addressed (only 7% unaffected within the Mexican network of PAs) with the current Mexican PAs network. Based on our ENM approach, we suggest that a combination of models of species inhabiting present TDFs and taking into account change scenarios represent an invaluable tool to create new PAs and ecological corridors, as a response to the increasing levels of habitat destruction and the effects of climate change on this ecosystem.

Impacto por huracanes en las praderas de Thalassia testudinum (Hydrocharitaceae) en el Caribe Mexicano

Hurricane impact on Thalassia testudinum (Hydrocharitaceae) beds in the Mexican Caribbean. Hurricanes have increased in strength and frequency as a result of global climate change. This research was conducted to study the spatio-temporal distribution and changes of Thalassia testudinum, the dominant species in Bahia de la Ascension (Quintana Roo, Mexico), when affected by heavy weather conditions. To complete this objective, a 2001 Landsat ETM+ image and the information from 525 sampling stations on morpho-functional and coverage of T. testudinum were used, and the seeds generated for the classification of eight benthic habitats. To quantify the changes caused by two hurricanes, we used two images, one of 1988 (Gilberto) and another of 1995 (Roxanne); other three data sets (2003, 2005 and 2007) were also used to describe the study area without major weather effects. Six categorial maps were obtained and subjected to analysis by 8 Landscape Ecology indexes, that describe the spatial characteristics, structure, function, change of the elements (matrix-patch-corridor), effects on ecosystems, connectivity, edges, shape and patch habitat fragmentation. Models indicate that T. testudinum may be classified as a continuum (matrix), since the fragments were not observed intermittently, but as a progression from minimum to maximum areas in reference to their coverage (ecological corridors). The fragments do not have a regular shape, indicating that the impacts are recent and may be due to direct effects (high-intensity hurricanes) or indirect (sediment). Fragments of type "bare soils" have a discontinuous distribution, and are considered to be the sites that have remained stable over a long timescale. While more dense coverage areas ("beds", "medium prairie" and "prairie") have low fragmentation and high connection of fragments. Features have an irregular perimeter and radial growth of formal; suggesting that the impact of meteors has no effect on the resilience of T. testudinum in this ecosystem, indicating good environmental quality to grow in this bay. Rev. Biol. Trop. 59 (1): 385-401. Epub 2011 March 01.

Thalassia testudinum es la macrófita dominante en Bahía de la Ascensión (Quintana Roo, México), se estudió para conocer su distribución espacio- temporal y determinar si fue afectada por el paso de huracanes que se han visto incrementados en fuerza y frecuencia por el cambio climático. Partiendo de una imagen Landsat ETM+de 2001 y usando información de grandes grupos morfofuncionales y de cobertura de T. testudinum adquiridas en 525 estaciones de muestreo, se obtienen las semillas para la clasificación supervisada de los hábitats bénticos (8 clases). Con el fin de cuantificar los cambios ocasionados por dos huracanes, se usaron dos imágenes, una de 1988 (Gilberto) y 1995 (Roxanne) y tres más (2003, 2005 y 2007) para monitoreo sin efectos meteorológicos mayores; a estos 6 mapas categóricos se les aplicó un análisis de Ecología del Paisaje usando 8 índices que describen las características espaciales, de estructura, función, cambio de los elementos (matriz-mancha-corredor), efectos sobre el ecosistema, conectividad, bordes, forma del parche y fragmentación del hábitat. Los modelos indican que T. testudinum puede clasificarse como un continuo (matriz), pues los fragmentos no se observan de forma intermitente, sino como una progresión de zonas mínimas a máximas en referencia a su cobertura (corredores ecológicos). No poseen una forma regular, indicando que los impactos son recientes y pueden ser debidos a efectos directos (huracanes de alta intensidad) e indirectos (aporte de sedimentos). Los fragmentos de tipo "suelos desnudos" presentan una distribución discontinua, considerándose sitios que han permanecido estables en una larga escala de tiempo; las zonas con coberturas más densas ("camas", "praderas medias" y "praderas") presentan baja fragmentación y alta conexión de sus fragmentos. Las características de poseer un perímetro irregular y crecimiento de formal radial, sugieren que el impacto de los meteoros no tiene efecto en la capacidad de resiliencia de T. testudinum en este ecosistema, indicando el buen estado de la calidad ambiental de la bahía para su crecimiento.

Bolsa floresta: um instrumento inovador para a promoção da saúde em comunidades tradicionais na Amazônia / Bolsa floresta: an innovative tool for health promotion in traditional communities in the Amazon

O Programa Bolsa Floresta implementa uma série de atividades prioneiras no campo da conservação ambiental e desenvolvimento sustentável na Amazônia. Sua concepção se insere no contexto das mudanças climáticas globais e de redução do desmatamento, com especial ênfase para as comunidades tradicionais da "Amazônia profunda". Este artigo descreve o conceito e a estratégia de implementação do Programa, com uma ênfase especial para as ações de saúde. Primeiro, é apresentado o contexto no qual foi concebido. Depois, apresentam-se o conceito, a estrutura e os resultados obtidos até setembro de 2008. Na seqüência, indicam-se o diagnóstico e as ações relacionadas com saúde pública. Finalmente, abordam-se o significado histórico e as perspectivas desse Programa.