Quantificação de biomassa e carbono da parte aérea em uma área de Mata Atlântica, na Serra da Cantareira, São Paulo

A atividade humana tem contribuído com as emissões de gases de efeito estufa (GEE) associadas, principalmente, com queima de combustíveis fósseis e mudanças no uso da terra. Assim, se faz necessário que sejam adotadas medidas visando o retardamento dos efeitos das mudanças climáticas. As florestas exercem papel essencial no balanço de carbono principalmente por funcionarem como sumidouros de CO2. Por outro lado, se desmatadas, promovem emissões e liberam parte do carbono estocado. A quantidade de biomassa florestal e o teor de carbono podem variar em função do tipo florestal, bem como de sua localização. Entretanto, fator importante diz respeito à confiabilidade dos dados mensurados neste tipo de pesquisa. A biomassa e o carbono da parte aérea podem ser determinados via método destrutivo, ou estimados via método não destrutivo. A construção do Rodoanel Mário Covas trecho norte e a supressão de uma área de Mata Atlântica possibilitou a realização de estudo de biomassa da parte aérea via método destrutivo. O objetivo deste trabalho foi estudar o tamanho e forma de parcelas, a intensidade amostral, quantificar a biomassa e o carbono na parte aérea, comparar métodos destrutivos e não destrutivos para a quantificação de biomassa e carbono na parte aérea, estudar a variação da densidade básica da madeira das espécies nas diferentes classes de DAP e grupos sucessionais e comparar as medidas de altura total e DAP obtidas a campo no inventário com as medidas coletadas após o corte. O tamanho mais conveniente de parcela foi 400 m 2, com forma retangular e dimensão de 10 x 40 m. A intensidade amostral variou entre 39 e 75 unidades amostrais. A biomassa da parte aérea obtida, via método destrutivo, foi de 188,3 Mg ha-1 e o carbono, 85,1 Mg ha-1. A biomassa estimada por equações alométricas da literatura foi subestimada, quando comparada ao valor real, obtido via método destrutivo. As menores classes de DAP apresentaram as maiores densidades básicas da madeira. A densidade básica foi 0,488 g cm-3 na média das espécies. A porcentagem de carbono contida nos troncos e galhos não diferiu entre as classes de DAP. O teor de carbono foi 45,41%, na média dos troncos e galhos. Espécies pioneiras acumularam maior quantidade de biomassa e carbono nos galhos e apresentaram maior densidade básica que as não pioneiras. A utilização dos dados coletados na fase de inventário e após o corte não afetaram os valores de biomassa estimados.

Genetically Engineered Crops: A Study of Major Environmental Implications and U.S. Policy

The adoption of genetically modified crops is becoming evermore common in United States agriculture. However, this relatively new technology carries a negative stigma and perceived risks that have resulted commonly in public disapproval. In the United States, bioengineered crops are highly regulated. The significance of environmental benefits such as decreased chemical impact, increased soil conservation, heightened carbon sequestration, decreased energy demands, and reduced air emissions, are important enough to warrant a revision to U.S. policy. The U.S. policy structure needs to be simplified and made more efficient to better facilitate the speed with which new GE products can, and should, be developed while still providing adequate mitigation of potential environmental risks such as species invasiveness and impacts on non-target species.

Biogeochemistry of the Eastern Weddell Gyre

The Southern Ocean (SO) plays a key role in modulating atmospheric CO2 via physical and biological processes. However, over much of the SO, biological activity is iron-limited. New in situ data from the Antarctic zone south of Africa in a region centered at -20°E - 25°E reveal a previously overlooked region of high primary production, comparable in size to the northwest African upwelling region. Here, sea ice together with enclosed icebergs is channeled by prevailing winds to the eastern boundary of the Weddell Gyre, where a sharp transition to warmer waters causes melting. This cumulative melting provides a steady source of iron, fuelling an intense phytoplankton bloom that is not fully captured by monthly satellite production estimates. These findings imply that future changes in sea-ice cover and dynamics could have a significant effect on carbon sequestration in the SO.

Eddy covariance and environmental data of boreal bogs plant species

In boreal bogs plant species are low in number, but they differ greatly in their growth forms and photosynthetic properties. We assessed how ecosystem carbon (C) sink dynamics were affected by seasonal variations in photosynthetic rate and leaf area of different species. Photosynthetic properties (light-response parameters), leaf area development and areal cover (abundance) of the species were used to quantify species-specific net and gross photosynthesis rates (PN and PG, respectively), which were summed to express ecosystem-level PN and PG. The ecosystem-level PG was compared with a gross primary production (GPP) estimate derived from eddy covariance measurements (EC). Species areal cover rather than differences in photosynthetic properties determined the species with the highest PG of both vascular plants and Sphagna. Species-specific contributions to the ecosystem PG varied over the growing season, which in turn determined the seasonal variation in ecosystem PG. The upscaled growing-season PG estimate, 230 g C/m**2, agreed well with the GPP estimated by the EC, 243 g C/m**2. Sphagna were superior to vascular plants in ecosystem-level PG throughout the growing season but had a lower PN. PN results indicated that areal cover of the species together with their differences in photosynthetic parameters shape the ecosystem-level C balance. Species with low areal cover but high photosynthetic efficiency appear to be potentially important for the ecosystem C sink. Results imply that functional diversity may increase the stability of C sink of boreal bogs.

Surface Elevation Change Processes in the Snohomish River Estuary, Washington

Estuaries provide crucial ecosystem functions and contain significant socio-economic value. Within Washington State, estuaries supply rearing habitat for juvenile salmon during their transition period from freshwater to open sea. In order to properly manage wetland resources and restore salmon habitat, the mechanisms through which estuaries evolve and adapt to pressures from climate change, most notably eustatic sea level rise, must be understood. Estuaries maintain elevation relative to sea level rise through vertical accretion of sediment. This report investigates the processes that contribute to local surface elevation change in the Snohomish Estuary, conveys preliminary surface elevation change results from RTK GPS monitoring, and describes how surface elevation change will be monitored with a network of RSET-MH’s. Part of the tidal wetlands within the Snohomish River Estuary were converted for agricultural and industrial purposes in the 1800’s, which resulted in subsidence of organic soils and loss of habitat. The Tulalip Tribes, the National Oceanic and Atmospheric Administration (NOAA), Northwest Indian Fisheries Commission (NWIFC), and the Environmental Protection Agency (EPA) are conducting a large-scale restoration project to improve ecosystem health and restore juvenile salmon habitat. A study by Crooks et al. (2014) used 210Pb and carbon densities within sediment cores to estimate wetland re-building capacities, sediment accretion rates, and carbon sequestration potential within the Snohomish Estuary. This report uses the aforementioned study in combination with research on crustal movement, tidal patterns, sediment supply, and sea level rise predictions in the Puget Sound to project how surface elevation will change in the Snohomish Estuary with respect to sea level rise. Anthropogenic modification of the floodplain has reduced the quantity of vegetation and functional connectivity within the Snohomish Estuary. There have been losses up to 99% in vegetation coverage from historic extents within the estuary in both freshwater and mesohaline environments. Hydrographic monitoring conducted by NOAA and the Tulalip Tribe shows that 85% of the historic wetland area is not connected to the main stem of the Snohomish (Jason Hall 2014, unpublished data, NOAA). As vegetation colonization and functional connectivity of the floodplains of the Snohomish estuary is re-established through passive and active restoration, sediment transport and accretion is expected to increase. Under the Intergovernmental Panel on Climate Change (IPCC) “medium- probability” scenario sea level is projected to rise at a rate of 4.28 mm/year in the Puget Sound. Sea level rise in the Snohomish Estuary will be exacerbated from crustal deformation from subsidence and post-glacial rebound, which are measured to be -1.4 mm/year and -0.02 mm/year, respectively. Sediment accretion rates calculated by Crooks et al. (2014) and RTK GPS monitoring of surface elevation change of the Marysville Mitigation site from 2011-2014 measured vertical accretion rates that range from -48-19 mm/year and have high spatial variability. Sediment supply is estimated at 490 thousand tons/year, which may be an under-estimate because of the exclusion of tidal transport in this value. The higher rates of sediment accretion measured in the Snohomish Estuary suggest that the Snohomish will likely match or exceed the pace of sea level rise under “medium-probability” projections. The network of RSET-MH instruments will track surface elevation change within the estuary, and provide a more robust dataset on rates of surface elevation change to quantify how vertical accretion and subsidence are contributing to surface elevation change on a landscape scale.

Financial and economic performance of long-rotation hardwood plantation investments in Queensland, Australia

In Queensland, Australia, there is presently a high level of interest in long-rotation hardwood plantation investments for sawlog production, despite the consensus in Australian literature that such investments are not financially viable. Continuing genetics, silviculture and processing research, and increasing awareness about the ecosystem services generated by plantations, are anticipated to make future plantings profitable and socio-economically desirable in many parts of Queensland. Financial and economic models of hardwood plantations in Queensland are developed to test this hypothesis. The economic model accounts for carbon sequestration, salinity amelioration and other ecosystem service values of hardwood plantations. A carbon model estimates the value of carbon sequestered, while salinity and other ecosystem service values are estimated by the benefit transfer method. Where high growth rates (20-25 m(3) ha(-1) year(-1)) are achievable, long-rotation hardwood plantations are profitable in Queensland Hardwood Regions 1, 3 and 7 when rural land values are less than $2300/ha. Under optimistic assumptions, hardwood plantations growing at a rate of 15 in 3 ha-1 year 1 are financially viable in Hardwood Regions 2, 4 and 8, provided land values are less than $1600/ha. The major implication of the economic analysis is that long-rotation hardwood plantation forestry is socio-economically justified in most Hardwood Regions, even though financial returns from timber production may be negative. (c) 2003 Elsevier B.V. All rights reserved.

Trade-offs between timber production and biodiversity in rainforest plantations: Emerging issues and an ecological perspective

During the past two centuries there have been three major paradigm shifts in the management of Australian rainforests and the use of their timbers: from felling native forests towards growing plantations; from viewing forests and plantations as mainly providers of timber to viewing them as sources of multiple benefits (e.g. timber, biodiversity, carbon sequestration, catchment protection, recreation, regional economic development); and from timber plantations being developed mainly by government on public land towards those established by private citizens, companies, or joint venture arrangements, on previously-cleared freehold land. Rainforest timber plantations are increasingly established for varied reasons, and with multiple objectives. Landholders are increasingly interested in the biodiversity values of their plantations. However, there are few guidelines on the changes to plantation design and management that would augment biodiversity outcomes, or on the extent to which this might require a sacrifice of production. [Abstract extract]

Developing a forest data portal to support multi-scale decision making

Forests play a pivotal role in timber production, maintenance and development of biodiversity and in carbon sequestration and storage in the context of the Kyoto Protocol. Policy makers and forest experts therefore require reliable information on forest extent, type and change for management, planning and modeling purposes. It is becoming increasingly clear that such forest information is frequently inconsistent and unharmonised between countries and continents. This research paper presents a forest information portal that has been developed in line with the GEOSS and INSPIRE frameworks. The web portal provides access to forest resources data at a variety of spatial scales, from global through to regional and local, as well as providing analytical capabilities for monitoring and validating forest change. The system also allows for the utilisation of forest data and processing services within other thematic areas. The web portal has been developed using open standards to facilitate accessibility, interoperability and data transfer.

Radiative forcing of natural forest disturbances

Forest disturbances are major sources of carbon dioxide to the atmosphere, and therefore impact global climate. Biogeophysical attributes, such as surface albedo (reflectivity), further control the climate-regulating properties of forests. Using both tower-based and remotely sensed data sets, we show that natural disturbances from wildfire, beetle outbreaks, and hurricane wind throw can significantly alter surface albedo, and the associated radiative forcing either offsets or enhances the CO2 forcing caused by reducing ecosystem carbon sequestration over multiple years. In the examined cases, the radiative forcing from albedo change is on the same order of magnitude as the CO2 forcing. The net radiative forcing resulting from these two factors leads to a local heating effect in a hurricane-damaged mangrove forest in the subtropics, and a cooling effect following wildfire and mountain pine beetle attack in boreal forests with winter snow. Although natural forest disturbances currently represent less than half of gross forest cover loss, that area will probably increase in the future under climate change, making it imperative to represent these processes accurately in global climate models.

Seawater carbonate chemistry and particulate organic particles during a semicontinuous batch culture experiment with Trichodesmium IMS101, 2007

Diazotrophic (N2-fixing) cyanobacteria provide the biological source of new nitrogen for large parts of the ocean. However, little is known about their sensitivity to global change. Here we show that the single most important nitrogen fixer in today's ocean, Trichodesmium, is strongly affected by changes in CO2 concentrations. Cell division rate doubled with rising CO2 (glacial to projected year 2100 levels) prompting lower carbon, nitrogen and phosphorus cellular contents, and reduced cell dimensions. N2 fixation rates per unit of phosphorus utilization as well as C:P and N:P ratios more than doubled at high CO2, with no change in C:N ratios. This could enhance the productivity of N-limited oligotrophic oceans, drive some of these areas into P limitation, and increase biological carbon sequestration in the ocean. The observed CO2 sensitivity of Trichodesmium could thereby provide a strong negative feedback to atmospheric CO2 increase.

Peatland depths and radiocarbon dates, recent decades, North America

Peatland ecosystems store about 500-600 Pg of organic carbon, largely accumulated since the last glaciation. Whether they continue to sequester carbon or release it as greenhouse gases, perhaps in large amounts, is important in Earth's temperature dynamics. Given both ages and depths of numerous dated sample peatlands, their rate of carbon sequestration can be estimated throughout the Holocene. Here we use average values for carbon content per unit volume, the geographical extent of peatlands, and ecological models of peatland establishment and growth, to reconstruct the time-trajectory of peatland carbon sequestration in North America and project it into the future. Peatlands there contain ~163 Pg of carbon. Ignoring effects of climate change and other major anthropogenic disturbances, the rate of carbon accumulation is projected to decline slowly over millennia as reduced net carbon accumulation in existing peatlands is largely balanced by new peatland establishment. Peatlands are one of few long-term terrestrial carbon sinks, probably important for global carbon regulation in future generations. This study contributes to a better understanding of these ecosystems that will assist their inclusion in earth-system models, and therefore their management to maintain carbon storage during climate change.

Barite Accumulation rates across Paleocene-Eocene Thermal Maximum (PETM)

Barite accumulation rates (BAR) have been measured from 12 DSDP/ODP site globally (DSDP site 525, 549 and ODP site 690, 738, 1051, 1209, 1215, 1220, 1221, 1263,1265 and 1266A) to reconstruct the export production across Paleocene Eocene Thermal Maximum (PETM) around 55.9 million year ago. Our results suggesting a general increase in export productivity. We propose that changes in marine ecosystems, resulting from high atmospheric partial pressure of CO2 and ocean acidification, led to enhanced carbon export from the photic zone to depth, thereby increasing the efficiency of the biological pump. We estimate that an annual carbon export flux out of the euphotic zone and into the deep ocean waters could have amounted to about 15 Gt during the PETM. About 0.4% of this carbon is expected to have entered the refractory dissolved organic pool, where it could be sequestered from the atmosphere for tens of thousands of years. Our estimates are consistent with the amount of carbon redistribution expected for the recovery from the PETM.

Mass accumulation rates of IODP Hole 320-U1333C

Understanding changes in export production through time provides insight into the response of the biological pump to global climate change, particularly during periods of rapid climate change. In this study we consider what role changes in export production may have had on carbon sequestration and how this may have contributed to the onset of the Eocene-Oligocene transition (EOT). In addition, we consider if these export production variations are dominantly controlled by orbitally driven climate variability. To accomplish these objectives, we report changes in export production in the Eastern Equatorial Pacific (EEP) from Site U1333 across the EOT reconstructed from a high-resolution record of marine barite accumulation rates (BAR). BAR fluctuations suggest synchronous declines in export production associated with the two-step increases in oxygen isotopes that define the transition. The reduction in productivity across the EOT suggests that the biological pump did not contribute to carbon sequestration and the cooling over this transition. We also report a previously undocumented peak in EEP export productivity before the EOT onset. This peak is consistent with export production proxies from the Southern Ocean, potentially implying a global driver for this precursor event. We propose that this enhanced export production and the associated carbon sequestration in the late Eocene may have contributed to the pCO2 drawdown at the onset of Antarctic glaciation.