Composition and aerial biomass dynamics after burning of a grassy-woody savanna in the Pantanal wetlands

O objetivo deste estudo foi avaliar a composição e dinâmica da biomassa aérea após a queima de uma savana gramíneo-lenhosa no Pantanal. Foram coletados dados mensais de freqüência de espécies, biomassa aérea e cobertura do solo durante 11 meses em uma área com queima (CQ) e outra sem queima (SQ), ambas sem pastejo. A queima reduziu a freqüência das gramíneas predominantes e condicionou aumento no número de espécies dicotiledôneas e ciperáceas. A produção de biomassa aérea total foi inferior na área com queima, embora a tendência de incremento tenha sido semelhante nas duas áreas. A produção de biomassa morta foi muito afetada pela queima, cuja produção, 11 meses após, representou aproximadamente 25% da obtida na área sem queima. A cobertura do solo foi inferior na área com queima e somente no quarto mês assemelhou-se à área sem queima.The purpose of this work was to evaluate composition and aerial biomass dynamics after burning of a grassy-woody savanna in the Pantanal wetlands, Brazil. During 11 months, data on species frequency, aerial biomass and soil cover were collected in an area with burning (WB) and another free of burning (FB), both not grazed. Burning reduced the frequency of the most predominant grasses and increased the number of dicotyledons and cyperaceae species. The production of total aerial biomass was lower in the WB area, despite an increase tendency that was similar in both areas. Litter production was strongly affected by burnings. After 11 months its production was approximately 25% of the production exhibited by the FB area. Soil cover was also lower in the WB and only after four months it was similar to the FB area

When enough should be enough: Improving the use of current agricultural lands could meet production demands and spare natural habitats in Brazil

Providing food and other products to a growing human population while safeguarding natural ecosystems and the provision of their services is a significant scientific, social and political challenge. With food demand likely to double over the next four decades, anthropization is already driving climate change and is the principal force behind species extinction, among other environmental impacts. The sustainable intensification of production on current agricultural lands has been suggested as a key solution to the competition for land between agriculture and natural ecosystems. However, few investigations have shown the extent to which these lands can meet projected demands while considering biophysical constraints. Here we investigate the improved use of existing agricultural lands and present insights into avoiding future competition for land. We focus on Brazil, a country projected to experience the largest increase in agricultural production over the next four decades and the richest nation in terrestrial carbon and biodiversity. Using various models and climatic datasets, we produced the first estimate of the carrying capacity of Brazil's 115 million hectares of cultivated pasturelands. We then investigated if the improved use of cultivated pasturelands would free enough land for the expansion of meat, crops, wood and biofuel, respecting biophysical constraints (i.e., terrain, climate) and including climate change impacts. We found that the current productivity of Brazilian cultivated pasturelands is 32–34% of its potential and that increasing productivity to 49–52% of the potential would suffice to meet demands for meat, crops, wood products and biofuels until at least 2040, without further conversion of natural ecosystems. As a result up to 14.3 Gt CO2 Eq could be mitigated. The fact that the country poised to undergo the largest expansion of agricultural production over the coming decades can do so without further conversion of natural habitats provokes the question whether the same can be true in other regional contexts and, ultimately, at the global scale

Chapter 5: Food Security

The current food system (production, transport, processing, packaging, storage, retail, consumption, loss and waste) feeds the great majority of world population and supports the livelihoods of over 1 billion people. Since 1961, food supply per capita has increased more than 30%, accompanied by greater use of nitrogen fertilisers (increase of about 800%) and water resources for irrigation (increase of more than 100%). However, an estimated 821 million people are currently undernourished, 151 million children under five are stunted, 613 million women and girls aged 15 to 49 suffer from iron deficiency, and 2 billion adults are overweight or obese. The food system is under pressure from non-climate stressors (e.g., population and income growth, demand for animal-sourced products), and from climate change. These climate and non-climate stresses are impacting the four pillars of food security (availability, access, utilisation, and stability)

Food security

Peer reviewe

A dynamic simulation model for planning and controlling grazing systems : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Agricultural Systems and Management at Massey University

This study reports on the development of a stochastic dynamic model to simulate a pastoral sheep enterprise. The event driven model was constructed using the iconic simulation package, ExtendTM. Events corresponded to the shifting of animals from one paddock to another. Each paddock was represented as a single entity with inherent attributes such as grazing area, sward characteristics and pasture production potential. The rotation sequence for grazing was determined by always allocating the flock of ewes, flock replacements or lambs to the paddock with the greatest pasture mass. Herbage mass was divided into three fractions: leaf, stem and dead. Pasture growth and senescence rates for individual paddocks were calculated from pasture leaf mass. A Micherlich-type function was used to relate leaf mass to total pasture growth. Senescence was assumed to increase linearly with herbage mass. Deterministic or stochastic pasture growth rate data can be generated by the model. Pasture responses to nitrogen were estimated dynamically and moderated for the farm by entering a user-defined response for a standard 50 kg/ha nitrogen application. Animal performance was calculated using average attributes for ewes, ewe hoggets and rams, but lambs were simulated individually. Lamb performance is affected by its date of birth and sex, and this information was generated by a sub-model for mixed-age ewe and ewe hogget reproduction. The potential herbage intake of the sheep was defined by their rumen fill and physiological energy demand, and herbage availability which was defined by pre-grazing green herbage mass and green herbage allowance for rotational grazing and leaf mass for continuous grazing. The grazing time spent in each paddock was derived from a linear interpolation of user-defined herbage allowances for each month of the year. The proportion of leaf, stem and dead material in the diet was calculated according to the proportion of these fractions in the sward and herbage availability. If animals were supplemented they consumed all of the material offered. This caused pasture substitution by decreasing the physiological energy demand and utilising rumen space otherwise taken up by grazed pasture. The partitioning of nutrients by animals was estimated from the ratio between energy intake and energy demand in an animal growth sub-model. This was driven by the DNA, protein and fat content of individual lambs and the average for animals in other sheep classes. Lambs were drafted for sale and graded according to user-defined threshold drafting weights. Carcass weight and fatness (GR) were generated from the live weight and sex of individuals lambs. A genetic optimisation algorithm was developed to optimise the systems control variables incorporated in the model. These were pasture allowance, supplement fed, nitrogen applied and lamb drafting weight. The model was evaluated against three New Zealand "farmlet" grazing experiments. This validation suggested re-parameterisation of the physiological intake limit is needed and that the British equation used to relate intake to leaf mass availability is overly sensible to the pasture conditions found in New Zealand. The model was also used to test the effects of pasture measurement errors on the profitability of a grazing system. Significant differences in profitability occurred when a CV of 40% in measurement of pasture mass was assumed (Gross margin = $NZ 495 /ha vs.$NZ 542 /ha and $NZ 570 /ha for 20 and 0$NZ 587 /ha, $NZ 576/ha and$NZ 519/ha, respectively for 40,20 and 0% CV in measurement estimates and no pasture accumulation rate variability). It was concluded that low gains in system performance can be expected by improving the accuracy of measuring pre-grazing herbage mass beyond the level (13-16% CV) provided by the correct use of current measurement techniques

Biomassa aérea e produção primária do estrato herbáceo em campo de Elyonurus muticus submetido à queima anual, no Pantanal

This work was conducted in a native grassland of the Pantanal, locally called "caronal" due to the dominance of Elyonurus muticus. The objectives were to evaluate the effect of annual burnings of "caronal" on the cumulative aerial biomass, aboveground net primary production (ANPP) of herbaceous communities and soil cover. Monthly data of cumulative aerial biomass were collected during two years in an area which was burned in September/95 and in August/96, and in another area which was free of burning. ANPP was estimated through differences between aerial live biomass gathered monthly. Annual burnings reduced cumulative aerial biomass about 36% in the first year and 50% in the second year. There was a tendency of reduction of cumulative aerial biomass with repetition of the burnings. The ANPP herbaceous communities in the areas free of burning and with burnings were 3,850 kg/ha and 4,980 kg/ha, in the first year, and 5,090 kg/ha and 2,880 kg/ha in the second, respectively. Thirty days after burning, the soil cover was about 30% and only four to six months after burning it was re-established as the area free of burning.O trabalho foi conduzido no Pantanal, em fitofisionomia de campo a savana, regionalmente denominada de caronal, pela dominância de Elyonurus muticus. Os objetivos foram avaliar o efeito da queima anual de caronal sobre a biomassa aérea acumulada, produção primária líquida da parte aérea (PPLA) do estrato herbáceo e cobertura do solo. Foram coletados dados mensais de biomassa aérea acumulada durante dois anos, em uma área com queima em set./95 e ago./96, e outra sem queima. A PPLA foi estimada através das diferenças de biomassa aérea viva coletada mensalmente. A queima reduziu a biomassa aérea acumulada em aproximadamente 36% no primeiro ano e 50% no segundo. Houve uma tendência de redução de biomassa acumulada com a repetição da queima. A PPLA do estrato herbáceo nas áreas sem queima e com queima foi 3.850 kg/ha e 4.980 kg/ha no primeiro ano, e 5.090 kg/ha e 2.880 kg/ha no segundo, respectivamente. A cobertura do solo 30 dias após a queima foi de aproximadamente 30%, e somente quatro a seis meses depois foi restabelecido o porcentual da área sem queima

Biomassa aérea e produção primária do estrato herbáceo em campo de Elyonurus muticus submetido à queima anual, no Pantanal

O trabalho foi conduzido no Pantanal, em fitofisionomia de campo a savana, regionalmente denominada de caronal, pela dominância de Elyonurus muticus. Os objetivos foram avaliar o efeito da queima anual de caronal sobre a biomassa aérea acumulada, produção primária líquida da parte aérea (PPLA) do estrato herbáceo e cobertura do solo. Foram coletados dados mensais de biomassa aérea acumulada durante dois anos, em uma área com queima em set./95 e ago./96, e outra sem queima. A PPLA foi estimada através das diferenças de biomassa aérea viva coletada mensalmente. A queima reduziu a biomassa aérea acumulada em aproximadamente 36% no primeiro ano e 50% no segundo. Houve uma tendência de redução de biomassa acumulada com a repetição da queima. A PPLA do estrato herbáceo nas áreas sem queima e com queima foi 3.850 kg/ha e 4.980 kg/ha no primeiro ano, e 5.090 kg/ha e 2.880 kg/ha no segundo, respectivamente. A cobertura do solo 30 dias após a queima foi de aproximadamente 30%, e somente quatro a seis meses depois foi restabelecido o porcentual da área sem queim

Agricultural R&D investments in Brazil: global responses and local spillovers

Brazil has made significant investments in public agricultural research and development (R&D) over the past 50 years. This policy priority has allowed the country to achieve high levels of total factor productivity (TFP) growth, especially in the past two decades1,2. These investments have benefitted consumers, both in Brazil and worldwide. Brazil had not fully recovered from a recent economic recession (mid-2014 to 2016) when the COVID-19 pandemic hit the global economy. Before COVID-19 public agricultural R&D expenditures in Brazil had already declined compared to its 2000-2017 levels2. The fiscal deterioration in the wake of this pandemic could further jeopardize Brazil’s capacity to invest in agricultural R&D. This paper explores the potential consequences of such a slowdown in public agricultural R&D expenditures in Brazil, and hence on productivity growth rates, land use, agricultural output, yields, and food prices at both the national and global levels over the 2017–2050 horizon