Impact of climatic seasons on the dynamics of carbon, nitrogen and mercury in soils of Brazilian biomes affected by gold mining.

Land use change, especially mining activities, contributes to anthropic CO2 emissions, leading to decreased carbon (C) storage and loss of biodiversity. Artisanal gold mining associated with the use of mercury (Hg) for amalgamation may change soil organic matter (SOM) contents, and the release of Hg into the environment generates serious environmental problems. Changes in soil biogeochemistry due to C loss and seasonal climate fluctuations affect Hg dynamics and can either increase or decrease its availability. Therefore, our objective was to evaluate the impact of mining on SOM and Hg geochemistry in four Brazilian biomes. We evaluated the dynamics of C and Hg in the dry and rainy seasons of mining and pasture areas by combining spectroscopic, thermogravimetric, and chemical extraction. The critical role of SOM in Hg retention and the influence of climatic seasons on C and nitrogen (N) stocks were highlighted, along with the availability of Hg in solution. Key findings indicated a 50 % reduction in soil C stocks in mined areas, exacerbated during dry seasons, which also saw up to a 70 % increase in bioavailable Hg. SOM played a critical role in Hg retention, with Hg availability closely linked to soil C stability. These results highlight the environmental degradation linked to mining and suggest strategies to mitigate these impacts by increasing SOM and immobilizing Hg. Amalgamation of gold directly into ore, as in the Amazon, has generated great soil Hg stocks, while Hg availability appeared to be governed by soil C stability. This information can serve as a basis for choosing strategies to mitigate environmental degradation caused by changes in land use in mining activities to promote increase in SOM and to immobilize Hg contents.

A deep-sea isopod that consumes Sargassum sinking from the ocean's surface.

Most deep-ocean life relies on organic carbon from the surface ocean. While settling primary production rapidly attenuates in the water column, pulses of organic material can be quickly transported to depth in the form of food falls. One example of fresh material that can reach great depths across the tropical Atlantic Ocean and Caribbean Sea is the pelagic macroalgae Sargassum. However, little is known about the deep-ocean organisms able to use this food source. Here, we encountered the isopod Bathyopsurus nybelini at depths 5002-6288 m in the Puerto Rico Trench and Mid-Cayman Spreading Center using the Deep Submergence Vehicle Alvin. In most of the 32 observations, the isopods carried fronds of Sargassum. Through an integrative suite of morphological, DNA sequencing, and microbiological approaches, we show that this species is adapted to feed on Sargassum by using a specialized swimming stroke, having serrated and grinding mouthparts, and containing a gut microbiome that provides a dietary contribution through the degradation of macroalgal polysaccharides and fixing nitrogen. The isopod's physiological, morphological, and ecological adaptations demonstrate that vertical deposition of Sargassum is a direct trophic link between the surface and deep ocean and that some deep-sea organisms are poised to use this material.

How do soil processes control the provision of ecosystem services in coastal wetlands?

Coastal wetlands are known for their diverse ecosystems, yet their soil characteristics are often misunderstood and thought to be monotonous. These soils are frequently subjected to saline water saturation, leading to unique soil processes. However, the combination and intensity of these processes can vary considerably across different ecosystems. In this study, we hypothesize that these diverse soil processes not only govern the geochemical conditions in coastal ecosystems but also influence their ability to deliver ecosystem services. To test this hypothesis, we conducted soil analyses in mangroves, seagrass meadows, and hypersaline tidal flats along the Brazilian coast. We used key soil properties as indicators of soil processes and developed a conceptual model linking soil processes and soil-related ecosystem services in these environments. Under more anoxic conditions, the intense soil organic matter accumulation and sulfidization processes in mangroves evidence their significance in terms of climate regulation through organic carbon sequestration and contaminants immobilization. Similarly, pronounced sulfidization in seagrasses underscores their ability to immobilize contaminants. In contrast, hypersaline tidal flats soils exhibit increased intensities of salinization and calcification processes, leading to a high capacity for accumulating inorganic carbon as secondary carbonates (CaCO3), underscoring their role in climate regulation through inorganic carbon sequestration. Our findings show that contrary to previously thought coastal wetlands are far from monotonous, exhibiting significant variations in the types and intensities of soil processes, which in turn influence their capacity to deliver ecosystem services. This understanding is pivotal for guiding effective management strategies to enhance ecosystem services in coastal wetlands.

The potential for carbon dioxide removal by enhanced rock weathering in the tropics: An evaluation of Costa Rica.

Tropical environments show great potential to sequester CO2 by enhanced rock weathering (ERW) of powdered mafic rocks applied to agricultural fields. This study seeks to assess carbon dioxide reduction (CDR) potential in the humid tropics (1) by experimental weathering of mafic rock powders in conditions simulating humid tropical soils, and (2) from weathering rates determined from a Holocene tropical soil chronosequence where parent material is andesitic sediments. Experimentally determined weathering rates by leaching of basaltic andesites from Costa Rica (Arenal and Barva) for 50 t ha-1 applications indicate potential sequestration of 2.4 to 4.5 t CO2 ha-1 yr-1, whereas the USGS basalt standard BHVO-1 yields a rate of 11.9 t ha-1 yr-1 (influenced by more mafic composition and finer particle size). The chronosequence indicates a rate of 1.7 t CO2 ha-1 yr-1. The weathering experiment consisted of 0.6 mm of powdered rock applied atop 12 mm of Ultisol at 35 °C. To simulate a tropical soil solution, 100-mL aliquots of a dilute solution of oxalic acid in carbonated DI water were rained onto soils over a 14-day period to simulate soil moisture in the humid tropics. Solutions were collected and analyzed by ICPMS for concentrations of leached cations. A potential ERW scenario for Costa Rica was assessed assuming that one-half of lowland agricultural kaolinitic soils (mainly Ultisols, common crop and pasture soils, excluding protected areas) were to receive 50 t ha-1 of annual or biennial applications of powdered mafic rock. With an experimentally determined humid tropical CDR rate for basaltic andesite (3.5 t ha-1 yr-1) and allowances for carbon costs (e.g. emissions from processing and delivery) that reduce CDR to a net 3.2 t ha-1 yr-1, potential annual CDR of this tropical nation is ∼2-4 million tons, amounting to ∼25-50 % of annual CO2 emissions (mainly from transportation in Costa Rica).

Assessment of land use cover changes, carbon sequestration and carbon stock in dry temperate forests of Chilas watershed, Gilgit-Baltistan

Abstract Land use and land cover change are affecting the global environment and ecosystems of the different biospheres. Monitoring, reporting and verification (MRV) of these changes is of utmost importance as they often results in several global environmental consequences such as land degradation, mass erosion, habitat deterioration as well as micro and macro climate of the regions. The advance technologies like remote sensing (RS) and geographical information system (GIS) are helpful in determining/ identifying these changes. In the current study area, changes in carbon stocks, notably in forest areas, are resulting in considerable dynamics of carbon stocks as a result of climate change and carbon sequestration. This study was carried out in the Diamer district of the Gilgit Baltistan (GB) Pakistan to investigate the change in cover change/land use change (particularly Forest Land use) as well as carbon sequestration potential of the forests in the district during almost last 25years. The land cover, temporal Landsat data (level 1, LIT) were downloaded from the USGS EROS (2016), for 1979-1989, 1990-2000 and 2001-2012. Change in land uses, particularly forest cover was investigated using GIS techniques. Forest inventory was carried out using random sampling techniques. A standard plot of size 0.1 ha (n=80) was laid out to determine the tree density, volume, biomass and C stocks. Simulation of C stocks was accomplished by application of the CO2FIX model with the data input from inventory. Results showed a decrease in both forest and snow cover in the region from 1979-2012. Similarly decrease was seen in tree volume, tree Biomass, dynamics of C Stocks and decrease was in occur tree density respectively. It is recommended we need further more like project such as BTAP (Billion Tree Afforestation Project) and green Pakistan project to increase the forest cover, to control on land use change, protect forest ecosystem and to protect snow cover.

Resumo O uso e as mudanças na cobertura da terra estão afetando o meio ambiente global e os ecossistemas das diferentes biosferas. O monitoramento, relatório e verificação (MRV) dessas mudanças são de extrema importância, pois muitas vezes resultam em várias consequências ambientais globais, como degradação da terra, erosão em massa, deterioração do hábitat, bem como micro e macroclima das regiões. As tecnologias avançadas, como sensoriamento remoto (RS) e sistema de informações geográficas (SIG), são úteis para determinar / identificar essas mudanças. Na área de estudo atual, as mudanças nos estoques de carbono, principalmente em áreas florestais, estão resultando em uma dinâmica considerável dos estoques de carbono como resultado das mudanças climáticas e do sequestro de carbono. Este estudo foi realizado no distrito de Diamer de Gilgit Baltistan (GB), Paquistão, para investigar a mudança na mudança de cobertura / mudança de uso da terra (particularmente uso de terras florestais), bem como o potencial de sequestro de carbono das florestas no distrito durante quase os últimos 25 anos. A cobertura da terra, os dados temporais do Landsat (nível 1, LIT), foram baixados do USGS EROS (2016), para 1979-1989, 1990-2000 e 2001-2012. Mudanças nos usos da terra, particularmente na cobertura florestal, foram investigadas usando técnicas de SIG. O inventário florestal foi realizado por meio de técnicas de amostragem aleatória. Um lote padrão de 0,1 ha (n = 80) foi estabelecido para determinar a densidade das árvores, volume, biomassa e estoques de C. A simulação dos estoques de C foi realizada pela aplicação do modelo CO2FIX com a entrada de dados do inventário. Os resultados mostraram uma diminuição na cobertura florestal e de neve na região de 1979 a 2012. Da mesma forma, diminuição foi observada no volume da árvore, biomassa das árvores, dinâmica dos estoques de C e diminuição na densidade das árvores, respectivamente. É recomendado que precisemos de mais projetos como o BTAP (Billion Tree Afforestation Project) e o projeto Green Pakistan para aumentar a cobertura florestal, controlar as mudanças no uso da terra, proteger o ecossistema florestal e proteger a cobertura de neve.

Divergence in functional traits in seven species of neotropical palms of different forest strata.

Functional traits are morphological and physiological characteristics that determine growth, reproduction, and survival strategies. The leaf economics spectrum proposes two opposing life history strategies: species with an "acquisitive" strategy grow fast and exploit high-resource environments, while species with a "conservative" strategy emphasize survival and slow growth under low resource conditions. We analyzed intra and interspecific variation in nine functional traits related to biomass allocation and tissue quality in seven Neotropical palm species from understory and canopy strata. We expected that the level of resources of a stratum that a species typically exploits would determine the dominance of either the exploitative or conservative strategy, as well as degree of divergence in functional traits between species. If this is correct, then canopy species will show an acquisitive strategy emphasizing traits targeting a larger size, whereas understory species will show a conservative strategy with traits promoting efficient biomass allocation and survival in the shade. Two principal components (57.22% of the variation) separated palm species into: (a) canopy species whose traits were congruent with the acquisitive strategy and emphasized large size (i.e., diameter, height, carbon content, and leaf area), and (b) understory species whose traits were associated with efficient biomass allocation (i.e., dry mass fraction -DMF- and tissue density). As we unravel the variation in functional traits in palms, which make up a substantial proportion of the tropical flora, we gain a deeper understanding of how plants adapt to environmental gradients.

Nitrous oxide and methane emissions from a Ferralsol as affected by loblolly pine cultivation time in subtropical Brazil.

We hypothesized that the age of loblolly pine stands influences soil methane (CH4) and nitrous oxide (N2O) emissions. This is a relevant topic to be studied in subtropical Brazil, where the pine plantation area is increasing considerably. We evaluated N2O and CH4 emissions for two years in a Ferralsol under loblolly pine (Pinus taeda L.) stands of 1, 9 and 18 year-olds and a native forest (NF). We calculated the net CO2eq emission by considering the N2O and CH4 emissions from soil and the carbon (C) accumulation as litter in the forest floor. The soil N2O emission reduced gradually over the loblolly pine cultivation years, whereas CH4 uptake rates showed no clear pattern. Soil N2O emission showed a positive relationship with soil temperature in NF, and with soil ammonium and nitrate intensities in the pine stands. Soil CH4 uptake was inversely related to water-filled pore space in the pine stands, but this relationship was not observed in NF. The soil CH4 uptake rate was 4.6 times higher (p < 0.10) in NF than the average uptake in loblolly pine stands. On the other hand, soil N2O emissions in 9 and 18-year-old stands were similar (p > 0.10) to those in NF (1.3 kg N ha-1 yr-1). Our results suggest that cultivation with loblolly pine for 18 years can reduce soil N2O emission, and the uptake of CH4 in this system offsets 17 % of N2O emissions. Furthermore, the C accumulation as litter in the forest floor of the mature pine stands (9- and 18-year-old) generated a net emission of -1.6 Mg CO2eq ha-1 yr-1, showing to be an expressive offsetting mechanism. Therefore, we conclude that aged loblolly forests can reach N2O emissions levels comparable to those of NF, and the C sequestration in these forests floor can significantly contribute to offset N2O emissions and act as sink for net atmospheric CO2eq.

Linking above and belowground carbon sequestration, soil organic matter properties, and soil health in Brazilian Atlantic Forest restoration.

Forest restoration mitigates climate change by removing CO2 and storing C in terrestrial ecosystems. However, incomplete information on C storage in restored tropical forests often fails to capture the ecosystem's holistic C dynamics. This study provides an integrated assessment of C storage in above to belowground subsystems, its consequences for greenhouse gas (GHG) fluxes, and the quantity, quality, and origin of soil organic matter (SOM) in restored Atlantic forests in Brazil. Relations between SOM properties and soil health indicators were also explored. We examined two restorations using tree planting ('active restoration'): an 8-year-old forest with green manure and native trees planted in two rounds, and a 15-year-old forest with native-planted trees in one round without green manure. Restorations were compared to reformed pasture and primary forest sites. We measured C storage in soil layers (0-10, 10-20, and 20-30 cm), litter, and plants. GHG emissions were assessed using CH4 and CO2 fluxes. SOM quantity was evaluated using C and N, quality using humification index (HLIFS), and origin using δ13C and δ15N. Nine soil health indicators were interrelated with SOM attributes. The primary forest presented the highest C stocks (107.7 Mg C ha-1), followed by 15- and 8-year-old restorations and pasture with 69.8, 55.5, and 41.8 Mg C ha-1, respectively. Soil C stocks from restorations and pasture were 20% lower than primary forest. However, 8- and 15-year-old restorations stored 12.3 and 28.3 Mg ha-1 more aboveground C than pasture. The younger forest had δ13C and δ15N values of 2.1 and 1.7‰, respectively, lower than the 15-year-old forest, indicating more C derived from C3 plants and biological N fixation. Both restorations and pasture had at least 34% higher HLIFS in deeper soil layers (10-30 cm) than primary forest, indicating a lack of labile SOM. Native and 15-year-old forests exhibited higher soil methane influx (141.1 and 61.9 µg m-2 h-1). Forests outperformed pasture in most soil health indicators, with 69% of their variance explained by SOM properties. However, SOM quantity and quality regeneration in both restorations approached the pristine forest state only in the top 10 cm layer, while deeper soil retained agricultural degradation legacies. In conclusion, active restoration of the Atlantic Forest is a superior approach compared to pasture reform for GHG mitigation. Nonetheless, the development of restoration techniques to facilitate labile C input into deeper soil layers (>10 cm) is needed to further improve soil multifunctionality and long-term C storage.

Comparison of carbon content between plantation and natural regeneration seedlings in Durango, Mexico.

Forest plantations and natural forests perform a relevant role in capturing CO2 and reducing greenhouse gas concentrations. The objective of this study was to compare the diameter increment, biomass and carbon accumulation in a plantation of Pinus durangensis and a naturally regenerated stand. The data were collected from 32 circular plots of 100 m2 (16 plots in the planted site and 16 in naturally regenerated area). At each plot, the diameter at the base (cm) and height (m) of all seedlings were measured using a Vernier and tape measure, and a seedling was destructively sampled collecting one cross-section at the base of the stump. The annual ring-width increment of each sampled seedling was recorded to obtain its diameter at the base and estimate annual aboveground biomass and carbon accumulation through allometric equations. The response variables were evaluated using mixed-effects ANOVA models. Results indicated that there were significant differences (P ≤ 0.05) on annual tree-ring width growth, biomass and carbon accumulation. The plantation seedlings showed significantly higher growth rates, biomass and carbon accumulation at most evaluated years. After 7 years of growth the lines of current annual increment (CAI) and mean annual increment (MAI) in basal diameter for both the plantation and the natural regeneration have not yet intersected. Both forest plantations and naturally regenerated stands of the studied tree species may be suitable alternatives to promote CO2 capture and increase timber production.

Carbon Sequestration in Resin-Tapped Slash Pine (Pinus elliottii Engelm.) Subtropical Plantations.

Every year more than 150,000 tons of resin used in a myriad of industrial applications are produced by Brazilian plantations of Pinus elliottii Engelm. (slash pine), which are also used for timber. A pine tree can be tapped for resin over a period of several years. Resin is a complex mixture of terpenes, which are carbon-rich molecules, presumably influencing pine plantation carbon budgets. A total of 270 trees (overall mean DBH of 22.93 ± 0.11 cm) of 14-, 24-, and 26-year-old stands had their C content measured. Three different treatments (intact, wounded panels, and wounded + chemically stimulated panels, 30 trees each) were applied per site. Above- and belowground biomass, as well as resin yield, were quantified for two consecutive years. Data were statistically evaluated using normality distribution tests, analyses of variance, and mean comparison tests (p ≤ 0.05). The highest resin production per tree was recorded in the chemically stimulated 14-year-old stand. Tree dry wood biomass, a major stock of carbon retained in cell wall polysaccharides, ranged from 245.69 ± 11.73 to 349.99 ± 16.73 kg among the plantations. Variations in carbon concentration ranged from 43% to 50% with the lowest percentages in underground biomass. There was no significant difference in lignin concentrations. Soils were acidic (pH 4.3 ± 0.10-5.83 ± 0.06) with low C (from 0.05% to 1.4%). Significantly higher C stock values were recorded in pine biomass compared to those reported for temperate zones. Resin-tapping biomass yielded considerable annual increments in C stocks and should be included as a relevant component in C sequestration assessments of planted pine forests.

An estimation of ecosystem services provided by urban and peri-urban forests: a case study in Juiz de Fora, Brazil / Uma estimativa dos serviços ecossistêmicos fornecidos pelas florestas urbanas e peri-urbanas: um estudo de caso em Juiz de Fora, Brasil

Urban expansion has led to the replacement of natural landscapes and environmental degradation, making cities and their urban and peri-urban forests (UPFs) vulnerable to climate change, especially on the formation of heat islands. Using i-Tree Canopy program (v. 7.0), we estimate the ecosystem services provided by UPFs in Juiz de Fora (Minas Gerais State, Southeastern Brazil), through the analysis of the (1) annual removal of atmospheric pollutants, (2) annual removal of atmospheric carbon, (3) total carbon stock in vegetation, and (4) the monetary benefits of sequestered and stocked carbon, based on Future Carbon Credit (CFI2Z1) as a monetary proxy. The results showed an average total amount of removal of 4.45 thousand tons of air pollution annually. The average annual total carbon storage was 158 thousand tons and the equivalent CO2 was 580 thousand tons, with an estimated total value of R$ 173 million per year. Significant values of the gross carbon stock (3.98 million tons) and equivalent CO2 (14.59 million tons) were found, being valued at R$ 4.35 billion. We concluded that the Juiz de Fora UPFs have a great potential for socio-environmental and economic benefits.

A expansão urbana levou à substituição de paisagens naturais por paisagens urbanas e à degradação ambiental, tornando cidades e suas florestas urbanas e peri-urbanas (FUPs) vulneráveis às mudanças climáticas, especialmente à formação de ilhas de calor. Utilizando o software i-Tree Canopy (v.7.0), estimamos os serviços ecossistêmicos promovidos pelas UPFs em Juiz de Fora (Minas Gerais, Sudeste do Brasil), por meio da análise de (1) remoção anual de poluentes atmosféricos, (2) remoção anual de carbono atmosférico, (3) estoque de carbono na vegetação e (4) os benefícios monetários do carbono sequestrado anualmente e estocado, utilizando o Mercado de Crédito de Carbono Futuro (CFI2Z1) como um proxy monetário. Os resultados apresentam uma quantidade total média de remoção de 4,45 mil toneladas de poluentes do ar, anualmente. O armazenamento médio anual de carbono total foi de 158 mil toneladas e o de CO2 equivalente foi de 580 mil toneladas, com um valor total estimado anual de R$ 173 milhões. Foram encontrados expressivos valores do estoque bruto de carbono (3,98 milhões de toneladas) e CO2 equivalente (14,59 milhões de toneladas), sendo avaliado em R$ 4,35 bilhões. Concluímos que as FUPs de Juiz de Fora possuem um grande potencial para benefícios socioambientais e econômicos.

An estimation of ecosystem services provided by urban and peri-urban forests: a case study in Juiz de Fora, Brazil / Uma estimativa dos serviços ecossistêmicos fornecidos pelas florestas urbanas e peri-urbanas: um estudo de caso em Juiz de Fora, Brasil

ABSTRACT: Urban expansion has led to the replacement of natural landscapes and environmental degradation, making cities and their urban and peri-urban forests (UPFs) vulnerable to climate change, especially on the formation of heat islands. Using i-Tree Canopy program (v. 7.0), we estimate the ecosystem services provided by UPFs in Juiz de Fora (Minas Gerais State, Southeastern Brazil), through the analysis of the (1) annual removal of atmospheric pollutants, (2) annual removal of atmospheric carbon, (3) total carbon stock in vegetation, and (4) the monetary benefits of sequestered and stocked carbon, based on Future Carbon Credit (CFI2Z1) as a monetary proxy. The results showed an average total amount of removal of 4.45 thousand tons of air pollution annually. The average annual total carbon storage was 158 thousand tons and the equivalent CO2 was 580 thousand tons, with an estimated total value of R$ 173 million per year. Significant values of the gross carbon stock (3.98 million tons) and equivalent CO2 (14.59 million tons) were found, being valued at R$ 4.35 billion. We concluded that the Juiz de Fora UPFs have a great potential for socio-environmental and economic benefits.

RESUMO: A expansão urbana levou à substituição de paisagens naturais por paisagens urbanas e à degradação ambiental, tornando cidades e suas florestas urbanas e peri-urbanas (FUPs) vulneráveis às mudanças climáticas, especialmente à formação de ilhas de calor. Utilizando o software i-Tree Canopy (v.7.0), estimamos os serviços ecossistêmicos promovidos pelas UPFs em Juiz de Fora (Minas Gerais, Sudeste do Brasil), por meio da análise de (1) remoção anual de poluentes atmosféricos, (2) remoção anual de carbono atmosférico, (3) estoque de carbono na vegetação e (4) os benefícios monetários do carbono sequestrado anualmente e estocado, utilizando o Mercado de Crédito de Carbono Futuro (CFI2Z1) como um proxy monetário. Os resultados apresentam uma quantidade total média de remoção de 4,45 mil toneladas de poluentes do ar, anualmente. O armazenamento médio anual de carbono total foi de 158 mil toneladas e o de CO2 equivalente foi de 580 mil toneladas, com um valor total estimado anual de R$ 173 milhões. Foram encontrados expressivos valores do estoque bruto de carbono (3,98 milhões de toneladas) e CO2 equivalente (14,59 milhões de toneladas), sendo avaliado em R$ 4,35 bilhões. Concluímos que as FUPs de Juiz de Fora possuem um grande potencial para benefícios socioambientais e econômicos.

Greenhouse gas balance and mitigation of pasture-based dairy production systems in the Brazilian Atlantic Forest Biome.

Brazilian cattle production is mostly carried out in pastures, and the need to mitigate the livestock's greenhouse gas (GHG) emissions and its environmental footprint has become an important requirement. The adoption of well-suited breeds and the intensification of pasture-based livestock production systems are alternatives to optimize the sector's land use. However, further research on tropical systems is necessary. The objective of this research was to evaluate the effect of Holstein (HO) and Jersey-Holstein (JE x HO) crossbred cows in different levels of pasture intensification (continuous grazing system with low stocking rate-CLS; irrigated rotational grazing system with high stocking rate-RHS), and the interaction between these two factors on GHG mitigation. Twenty-four HO and 24 JE x HO crossbred dairy cows were used to evaluate the effect of two grazing systems on milk production and composition, soil GHG emissions, methane (CH4) emission, and soil carbon accumulation (0-100 cm). These variables were used to calculate carbon balance (CB), GHG emission intensity, the number of trees required to mitigate GHG emission, and the land-saving effect. The number of trees necessary to mitigate GHG emission was calculated, considering the C balance within the farm gate. The mitigation of GHG emissions comes from the annual growth rate and accumulation of C in eucalyptus trees' trunks. The CB of all systems and genotypes presented a deficit in carbon (C); there was no difference for genotypes, but RHS was more deficient than CLS (-4.99 to CLS and -28.72 to RHS ton CO2e..ha-1.year-1). The deficit of C on GHG emission intensity was similar between genotypes and higher for RHS (-0.480 to RHS and -0.299 to CLS kg CO2e..kg FCPCmilk-1). Lower GHG removals (0.14 to CLS higher than 0.02 to RHS kg CO2e..kg FCPCmilk-1) had the greatest influence on the GHG emission intensity of milk production. The deficit number of trees to abatement emissions was higher to HO (-46.06 to HO and -38.37 trees/cow to JE x HO) and to RHS (-51.9 to RHS and -33.05 trees/cow to CLS). However, when the results are expressed per ton of FCPCmilk, there was a difference only between pasture management, requiring -6.34 tree. ton FCPCmilk-1 for the RHS and -3.99 tree. ton FCPCmilk-1 for the CLS system. The intensification of pastures resulted in higher milk production and land-saving effect of 2.7 ha. Due to the reservation of the pasture-based dairy systems in increasing soil C sequestration to offset the GHG emissions, especially enteric CH4, planting trees can be used as a mitigation strategy. Also, the land-save effect of intensification can contribute to the issue, since the area spared through the intensification in pasture management becomes available for reforestation with commercial trees.

Silvopastoral systems for offsetting livestock emissions in the tropics: a case study of a dairy farm in Costa Rica.

Ways are being sought to reduce the environmental impact of ruminant livestock farming. Integration of trees into farming systems has been advocated as a measure to deliver ecosystem services, inter alia climate regulation and adaptation, water quality regulation, provisioning of fibre, fuel and habitats to support biodiversity. Despite the rapid expansion of cattle farming in the tropics, notably in Latin America, there is little robust evidence on the extent to which trees are able to mitigate the effects of cattle farming in this ecological zone. This article describes a case study conducted on a large, specialised dairy farm in Costa Rica, where two-thirds of the field boundaries are live tree fences. For the first time, this study quantifies the offset potential of trees by estimating rate of carbon sequestration in a silvopastoral system (SPS) in the tropics. It was found that over a 30-month interval, trees sequestered 1.43 Mg C ha-1 year-1 above and below ground. Attributional life cycle assessment (LCA) (cradle to farm gate) was applied to calculate the carbon footprint of milk produced on the farm for the years 2016 to 2018. Trees in live fences offset 21-37% of milk footprints, resulting in residual net footprints of 0.75±0.25 to 0.84±0.26 kg CO2 eq. kg-1 milk. Exclusion of life cycle emissions that may not fall within national emission inventory accounting (e.g. fertiliser manufacture and feed production) increased the mean offset from 27 to 34% of gross milk footprint. Although based on temporally limited data (30 months), our findings indicate that a live fence SPS could play an important role in short- to medium-term climate mitigation from livestock production, buying time for deployment of long-term mitigation and adaptation planning. Supplementary Information: The online version contains supplementary material available at 10.1007/s13593-022-00834-z.

The environmental cost of broiler production and carbon sequestration potential of eucalyptus plantations around farms in Mato Grosso do Sul, Brazil.

The present study aimed to evaluate the environmental cost of the production process of broilers from the approach of emergy accounting and carbon sequestration potential for broiler farms. The study assessed a standard farm of the conventional system containing ten houses in 19 ha. We evaluated the following indices solar transformity (Tr), renewability (%R), emergy yield ratio (EYR), emergy investment ratio (EIR), environmental loading ratio (ELR), emergy sustainability index (ESI), and emergy exchange ratio (EER) and carbon sequestration potential of eucalyptus plantation. The total emergy input was 2.79E-06 seJ ha-1 y-1 for the broiler growth process. The highest investment in the production process was related to materials, which came from feeding and electricity. The renewability index indicated the low sustainability of the system with increased consumption of economical materials and equipment, with a low proportion of the emergy use of renewable resources. High investment in broilers production in the conventional system generates an environmental loading ratio that indicates high environmental degradation. Planting trees in the surrounding areas of the farm facilities can minimize the externalities of the production system with the plantation carbon sequestration potential.

Biochar increases soil carbon pools: Evidence from a global meta-analysis.

Biochar is a carbon-rich material that increases soil C sequestration and mitigates climate change. However, due to the variability of experimental conditions, types of biochar and soil, the influence of biochar on the accumulation of different soil carbon fractions remains unclear. Therefore, a meta-analysis was performed that included 586 paired comparisons obtained from 169 studies conducted in various countries around the globe. The data set average showed significant relative increases of 64.3, 84.3, 20.1, 22.9 and 42.1% for total C, organic C, microbial biomass C, labile C and fulvic acid, respectively. The dissolved organic C, humic acid and humin fractions showed no significant variations. The relative increase in TC was favored by increasing biochar rates applied to fine-textured soils with low C content in temperate climate regions seen through short-term experiments conducted under controlled conditions. This behavior was different for each soil C fraction. Therefore, variations between experimental conditions, types of biochar and soil show that it is necessary to consider multiple factors when choosing the conditions of biochar use to maximize C sequestration in the soil and/or the increase of labile C fractions in the soil.

Fast recovery of soil macrofauna in regenerating forests of the Amazon.

The emergence of secondary forests in deforested tropical regions represents an opportunity to mitigate biodiversity loss and climate change, but there is still debate on how fast and to which level these forests can recover biodiversity. Recent studies have shown that the recovery of plant and vertebrate species richness is relatively fast, but the pace of recovery for other groups remains unclear. Soil macroinvertebrates play critical roles on litter decomposition and seed dispersal, therefore the pace of their recovery has consequences for the entire forest ecosystem. We investigated how fast broad taxonomic groups of soil macrofauna recover in the first 30 years of forest regeneration using forests older than 50 years as reference. We surveyed the number, diversity and abundance of 19 broad taxonomic groups of soil macrofauna in 85 sites located in Brazilian Amazon, covering forests of different ages and clearing frequencies. Forest age and clearing frequency were obtained accurately from Landsat images in forests up to 30 years old. We used regression analysis to determine (a) the effects forest age and clearing frequency on macrofauna groups in secondary forests up to 30 years old; and (b) the changes in macrofauna groups between young forests (up to 10 years old), median age forests (between 10 and 30 years old) and forests older than 50 years. We found that the number and diversity of macrofauna groups recover rapidly in the first 10 years of forest regrowth, but show slower change among older forests. This rapid recovery was also observed in the abundance of several taxonomic groups and for predators and detritivores as functional groups. Forest clearing frequency had no effect on the number or the diversity of macrofauna groups, but the abundance of ants increased as forest was cleared more often. Our results for soil macrofauna align with those in plant and vertebrate studies showing that secondary forests quickly recover a large part of their biodiversity and ecological functions. Therefore, global-scale conservation strategies are needed to ensure the opportunity for secondary forests to grow. ​.

Habitat Quality Differentiation and Consequences for Ecosystem Service Provision of an Amazonian Hyperdominant Tree Species.

Ecosystem services of Amazonian forests are disproportionally produced by a limited set of hyperdominant tree species. Yet the spatial variation in the delivery of ecosystem services by individual hyperdominant species across their distribution ranges and corresponding environmental gradients is poorly understood. Here, we use the concept of habitat quality to unravel the effect of environmental gradients on seed production and aboveground biomass (AGB) of the Brazil nut, one of Amazonia's largest and most long-lived hyperdominants. We find that a range of climate and soil gradients create trade-offs between density and fitness of Brazil nut trees. Density responses to environmental gradients were in line with predictions under the Janzen-Connell and Herms-Mattson hypotheses, whereas tree fitness responses were in line with resource requirements of trees over their life cycle. These trade-offs resulted in divergent responses in area-based seed production and AGB. While seed production and AGB of individual trees (i.e., fitness) responded similarly to most environmental gradients, they showed opposite tendencies to tree density for almost half of the gradients. However, for gradients creating opposite fitness-density responses, area-based seed production was invariable, while trends in area-based AGB tended to mirror the response of tree density. We conclude that while the relation between environmental gradients and tree density is generally indicative of the response of AGB accumulation in a given area of forest, this is not necessarily the case for fruit production.