Agriculture currently contributes significantly to the increase of CO2 in the atmosphere, primarily through the conversion of native ecosystems to agricultural uses in the tropics. Yet there are major opportunities for mitigation of CO2 and other greenhouse gas emissions through changes in the use and management of agricultural lands. Agricultural mitigation options can be broadly divided into two categories: (I) strategies to maintain and increase stocks of organic C in soils (and biomass), and (ii) reductions in fossil C consumption, including reduced emissions by the agricultural sector itself and through agricultural production of biofuels to substitute for fossil fuels. Reducing the conversion of new land to agriculture in the tropics could substantially reduce CO2 emissions, but this option faces several difficult issues including population increase, land tenure and other socio-political factors in developing countries. The most significant opportunities for reducing tropical land conversions are in the humid tropics and in tropical wetlands. An important linkage is to improve the productivity and sustainability of existing agricultural lands in these regions. Globally, we estimate potential agricultural CO2 mitigation through soil C sequestration to be 0.4-0.9 Pg C y-1, through better management of existing agricultural soils, restoration of degraded lands, permanent "set-asides" of surplus agricultural lands in temperate developed countries and restoration of 10-20% of former wetlands now being used for agriculture. However, soils have a finite capacity to store additional C and therefore any increases in C stocks following changes in management would be largely realized within 50-100 years. Mitigation potential through reducing direct agricultural emissions is modest, 0.01-0.05 Pg C y-1. However, the potential to offset fossil C consumption through the use of biofuels produced by agriculture is substantial, 0.5-1.6 Pg C y-1, mainly through the production of dedicated biofuel crops with a smaller contribution (0.2-0.3 Pg C y-1) from crop residues. Many agricultural mitigation options represent "win-win" situations, in that there are important side benefits, in addition to CO2 mitigation, that could be achieved, e.g. improved soil fertility with higher soil organic matter, protection of lands poorly suited for permanent agriculture, cost saving for fossil fuel inputs and diversification of agricultural production (e.g. biofuels). However, the needs for global food production and farmer/societal acceptability suggest that mitigation technologies should conform to: (I) the enhancement of agricultural production levels in parts of the world where food production and population demand are in delicate balance and (ii) the accrual of additional benefits to the farmer (e.g., reduced labor, reduced or more efficient use of inputs) and society at large.

CO2 Mitigation by Agriculture: An Overview

Sustained productivity in intensively managed forest plantations

iofuels are widely seen as a feasible alternative to oil. Indeed, in 1995 the Clinton Administration proposed amendments to the Clean Air Act that would require gasoline sold in the nine most polluted US cities to contain additives from renewable sources, such as grain alcohol. This move, even if blocked by a three-judge panel of the US Court of Appeals in Washington, DC (Southerland 1995), has helped to focus attention on the question of whether research and development in biofuel production from agricultural crops should be increased (e.g., Abelson 1995). In Europe, similar fiscal and regulatory provisions have already been introduced (Chartier and Savanne 1992, Sourie et al. 1992). These policies assume that biofuels have the potential to reduce current dependence of industrialized societies on rapidly disappearing fossil energy stocks and that biofuels are desirable from an ecological point of view. But are these assumptions correct?

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Feasibility of Large-Scale Biofuel Production

The Neotropical Atlantic Forest is one of the world’s top biodiversity hotspot. Originally, the forest extended over 1.5 million km2 along the South American Atlantic coast, covering tropical and subtropical climates across highly heterogeneous relief conditions, which led to outstanding levels of endemism and species richness. Unfortunately, the Atlantic Forest has been historically altered by humans, which has resulted in severe habitat loss and fragmentation. The forest cover is now reduced to around 12% of its original extent, including regenerating areas and degraded forests, which are mostly spread in small fragments. As a result, many species are currently threatened to global extinction, with populations collapsing on local and regional scales. In this chapter, we reviewed the state of the art of Atlantic Forest biodiversity knowledge, pointing out the main achievements obtained by several research groups during the last decades. Additionally, we (1) propose a new sub-division of biogeographical sub-regions into 55 sectors considering 2,650 sub-watersheds, using niche theory and bioclimatic data; (2) describe the original and present distribution of the Atlantic Forest; and (3) relate the forest distribution to elevation and geomorphometric information (aspect and terrain orientation). Forest protection and restoration efforts, and potential ecosystem services are also examined as key topics driving the future of the Atlantic Forest biodiversity.

The Brazilian Atlantic Forest: A Shrinking Biodiversity Hotspot

Biomass energy in industrialised countries—a view of the future

This work aimed to verify the influence of the under shading period in the parameters employed to evaluate Trema micrantha (crindiuva) seedling quality pattern. The research was carried out using a randomized design, with four replications per treatment and 88 plants per replication. Three evaluations were performed at 90, 120 and 150 days after emergence. The following treatments were used in the evaluation: Evaluation I, 45, 60, 75 and 90; Evaluation II, 45, 60, 75, 90, 105 and 120 and Evaluation III, 45, 60, 75, 90, 105, 120, 135 and 150 days under shading with 48% of solar radiation retention, respectively. The morphological parameters of the seedlings, their relationships, and the Dickson quality index were evaluated. Seedlings developed under the longer shading periods presented higher shoot heights and leaf area but the lowest values for seedling quality, such as smaller stem diameter, root dry mass and the Dickson quality index. They also presented an increase in shoot height/stem diameter and shoot/root ratios. Period under shading did not affect significantly the parameters for leaf area, leaf dry mass, shoot and total. Seedlings showed better quality patterns at 120 days, when grown under 45 and 60 days under shading. The Dickson's quality index was the best and the most suitable parameter to evaluate the target seedling grown in a suspended nursery.

https://www.scielo.br/pdf/rarv/v26n4/a15v26n4.pdf

Padrão de qualidade de mudas de Trema micrantha (L.) Blume, produzidas sob diferentes períodos de sombreamento

An experiment was carried out to study the morphological parameters used to evaluate the quality of Eucalyptus grandis seedlings produced in different tube sizes. A mixture of 80% organic compound (CO) and 20% charcoal powder fertilized with and without N, P and K was used as substrate. Four sizes of hard plastic tubes at the volumes of 50, 110, 200 and 280 cm 3 were used as packaging. Height and height/weight relationship of the aerial part dry matter should be considered, since although providing a satisfactory contribution to seedling quality pattern, the parameters did not present a destructive process. The use of height only to estimate the quality of Eucalyptus grandis seedlings in the 110 cm 3 volume tube when they were 90-day old should be used, since it presents a satisfactory relative contribution, besides being a nondestructive, easily determined and measured parameter.

/pdf/parametros-morfologicos-na-avaliacao-da-qualidade-de-mudas-3kfqir0hpg.pdf

Parâmetros morfológicos na avaliação da qualidade de mudas de eucalyptus grandis

An experiment was carried out to study the growth of Eucalyptus grandis seedlings produced in different sized tubes and N-P-K fertilization. A mixture of 80% organic compound (CO) and 20% charcoal powder fertilized with and without N, P and K was used as substrate. Four sizes of hard plastic tubes at the volumes of 50, 110, 200 and 280 cm3 were used as containers. The tube volumes must be considered for producing Eucalyptus grandis seedlings. Although the highest growths occurred in the larger tubes, these tubes should not be used because the seedling heights far surpass the ones considered as technically optimum for planting, and have a higher production cost. At 60 days of age, the seedlings are still small and quite tender, and do not present the hardness appropriate to field planting. At 120 days after sowing, the restriction to root growth and seedling height is affected even in the larger tubes, thus this is not the indicated age. The 110 cm3 volume tube must be considered for 90-day old seedlings.

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Crescimento de mudas de Eucalyptus grandis em diferentes tamanhos de tubetes e fertilização N-P-K

O objetivo deste trabalho foi avaliar a influencia de tres niveis de sombreamento artificial (0,30 e 60%) sobre a producao de materia seca, a concentracao de nitrogenio e as caracteristicas morfologicas de seis especies de gramineas forrageiras tropicais (Andropogon gayanus, cv. Planaltina, Brachiaria brizantha, cv. Marandu, B. decumbens, Melinis minutiflora, Panicum maximum, cv. Vencedor, e Setaria anceps, cv. Kazungula). Foi usado delineamento em blocos ao acaso, com parcelas subdivididas e quatro repeticoes; nas parcelas foram distribuidos os niveis de sombreamento e nas subparcelas, as especies forrageiras. Os resultados demonstram que o sombreamento influenciou a producao de materia seca, a concentracao de N e as caracteristicas morfologicas das especies avaliadas. A producao forrageira foi influenciada diferencialmente pelo sombreamento. A producao de materia seca do P. maximum, cv. Vencedor foi 19,72% maior a sombra moderada que a pleno sol. A producao de S. anceps, cv. Kazungula, entretanto, nao foi influenciada pelo sombreamento. As demais especies tiveram decrescimo da producao de materia seca com a reducao da luminosidade. Em todas as especies, houve aumento da concentracao de N e reducao do teor de materia seca da forragem, que se tornou mais suculenta a sombra. As caracteristicas morfologicas nao apresentaram comportamento padrao, variando conforme a especie avaliada.

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Produção forrageira de gramíneas cultivadas sob luminosidade reduzida

/pdf/morphological-parameters-quality-for-the-evalution-of-1yqu0uaf5r.pdf

Laércio Couto

Papers

Padrão de qualidade de mudas de Trema micrantha (L.) Blume, produzidas sob diferentes períodos de sombreamento

Parâmetros morfológicos na avaliação da qualidade de mudas de eucalyptus grandis

Crescimento de mudas de Eucalyptus grandis em diferentes tamanhos de tubetes e fertilização N-P-K

Produção forrageira de gramíneas cultivadas sob luminosidade reduzida

Morphological parameters quality for the evalution of Eucalyptus grandis seedling