60 research outputs found
Agro-Ecological Class Stability Decreases in Response to Climate Change Projections for the Pacific Northwest, USA
Climate change will impact bioclimatic drivers that regulate the geospatial distribution of dryland agro-ecological classes (AECs). Characterizing the geospatial relationship between present AECs and their bioclimatic controls will provide insights into potential future shifts in AECs as climate changes. The major objectives of this study are to quantify empirical relationships between bioclimatic variables and the current geospatial distribution of six dryland AECs of the inland Pacific Northwest (iPNW) of the United States; and apply bioclimatic projections from downscaled climate models to assess geospatial shifts of AECs under current production practices. Two Random Forest variable selection algorithms, VarSelRF and Boruta, were used to identify relevant bioclimatic variables. Three bioclimatic variables were identified by VarSelRF as useful for predictive Random Forest modeling of six AECs: (1) Holdridge evapotranspiration index; (2) spring precipitation (March, April, and May); and (3) precipitation of the warmest 4-month season (June, July, August, and September). Super-imposing future climate scenarios onto current agricultural production systems resulted in significant geospatial shifts in AECs. The Random Forest model projected a 58 and 63% increase in area under dynamic annual crop-fallow-transition (AC-T) and dynamic grain-fallow (GF) AECs, respectively. By contrast, a 46% decrease in area was projected for stable AC-T and dynamic annual crop (AC) AECs across all future time periods for Representative Concentration Pathway (RCP) 8.5. For the same scenarios, the stable AC and GF AECs showed the least declines in area (8 and 13%, respectively), compared to other AECs. Future spatial shifts from stable to dynamic AECs, particularly to dynamic AC-T and dynamic GF AECs would result in more use of fallow, a greater hazard for soil erosion, greater cropping system uncertainty, and potentially less cropping system flexibility. These projections are counter to cropping system goals of increasing intensification, diversification, and productivity
Global wheat production with 1.5 and 2.0°C above preâindustrial warming
Efforts to limit global warming to below 2°C in relation to the preâindustrial level are under way, in accordance with the 2015 Paris Agreement. However, most impact research on agriculture to date has focused on impacts of warming >2°C on mean crop yields, and many previous studies did not focus sufficiently on extreme events and yield interannual variability. Here, with the latest climate scenarios from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project, we evaluated the impacts of the 2015 Paris Agreement range of global warming (1.5 and 2.0°C warming above the preâindustrial period) on global wheat production and local yield variability. A multiâcrop and multiâclimate model ensemble over a global network of sites developed by the Agricultural Model Intercomparison and Improvement Project (AgMIP) for Wheat was used to represent major rainfed and irrigated wheat cropping systems. Results show that projected global wheat production will change by â2.3% to 7.0% under the 1.5°C scenario and â2.4% to 10.5% under the 2.0°C scenario, compared to a baseline of 1980â2010, when considering changes in local temperature, rainfall, and global atmospheric CO2 concentration, but no changes in management or wheat cultivars. The projected impact on wheat production varies spatially; a larger increase is projected for temperate high rainfall regions than for moderate hot low rainfall and irrigated regions. Grain yields in warmer regions are more likely to be reduced than in cooler regions. Despite mostly positive impacts on global average grain yields, the frequency of extremely low yields (bottom 5 percentile of baseline distribution) and yield interâannual variability will increase under both warming scenarios for some of the hot growing locations, including locations from the second largest global wheat producerâIndia, which supplies more than 14% of global wheat. The projected global impact of warming <2°C on wheat production is therefore not evenly distributed and will affect regional food security across the globe as well as food prices and trade
Sustainable and Equitable Increases in Fruit and Vegetable Productivity and Consumption are Needed to Achieve Global Nutrition Security
Increased intake of fruits and vegetables (F&V) is recommended for most populations across the globe. However, the current state of global and regional food systems is such that F&V availability, the production required to sustain them, and consumer food choices are all severely deficient to meet this need. Given the critical state of public health and nutrition worldwide, as well as the fragility of the ecological systems and resources on which they rely, there is a great need for research, investment, and innovation in F&V systems to nourish our global population. Here, we review the challenges that must be addressed in order to expand production and consumption of F&V sustainably and on a global scale. At the conclusion of the workshop, the gathered participants drafted the âAspen/Keystone Declarationâ (see below), which announces the formation of a new âCommunity of Practice,â whose area of work is described in this position paper. The need for this work is based on a series of premises discussed in detail at the workshop and summarized herein. To surmount these challenges, opportunities are presented for growth and innovation in F&V food systems. The paper is organized into five sections based on primary points of intervention in global F&V systems: (1) research and development, (2) information needs to better inform policy & investment, (3) production (farmers, farming practices, and supply), (4) consumption (availability, access, and demand), and (5) sustainable & equitable F&V food systems and supply chains
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BioEarth: Envisioning and developing a new regional earth system model to inform natural and agricultural resource management
As managers of agricultural and natural resources are confronted with uncertainties in global change impacts, the complexities associated with the interconnected cycling of nitrogen, carbon, and water present daunting management challenges. Existing models provide detailed information on specific sub-systems (e.g., land, air, water, and economics). An increasing awareness of the unintended consequences of management decisions resulting from interconnectedness of these sub-systems, however, necessitates coupled regional earth system models (EaSMs). Decision makersâ needs and priorities can be integrated into the model design and development processes to enhance decision-making relevance and âusabilityâ of EaSMs. BioEarth is a research initiative currently under development with a focus on the U.S. Pacific Northwest region that explores the coupling of multiple stand-alone EaSMs to generate usable information for resource decision-making. Direct engagement between model developers and non-academic stakeholders involved in resource and environmental management decisions throughout the model development process is a critical component of this effort. BioEarth utilizes a bottom-up approach for its land surface model that preserves fine spatial-scale sensitivities and lateral hydrologic connectivity, which makes it unique among many regional EaSMs. This paper describes the BioEarth initiative and highlights opportunities and challenges associated with coupling multiple stand-alone models to generate usable information for agricultural and natural resource decision-making
Similar estimates of temperature impacts on global wheat yield by three independent methods
The potential impact of global temperature change on global crop yield has recently been assessed with different methods. Here we show that grid-based and point-based simulations and statistical regressions (from historic records), without deliberate adaptation or CO2 fertilization effects, produce similar estimates of temperature impact on wheat yields at global and national scales. With a 1â°C global temperature increase, global wheat yield is projected to decline between 4.1% and 6.4%. Projected relative temperature impacts from different methods were similar for major wheat-producing countries China, India, USA and France, but less so for Russia. Point-based and grid-based simulations, and to some extent the statistical regressions, were consistent in projecting that warmer regions are likely to suffer more yield loss with increasing temperature than cooler regions. By forming a multi-method ensemble, it was possible to quantify âmethod uncertaintyâ in addition to model uncertainty. This significantly improves confidence in estimates of climate impacts on global food security.<br/
AnĂĄlisis de los componentes de conductancia hidrĂĄulica en ĂĄrboles maduros de cerezo dulce en condiciones de campo
As a necessary step towards understanding soil water extraction and
plant water relationships, the components of hydraulic conductance (K)
of mature sweet cherry ( Prunus avium L.) trees were evaluated in
situ based on a OhmÂŽs law analog method. In June 2004, K was
determined for 10-yr-old âBingâ/âGiselaÂź
5â trees, from simultaneous measurements of whole canopy gas
exchange and leaf (sunlit and shaded) and stem water potentials (y).
Leaf water potential of sunlit leaves was lower than shaded leaves,
reaching minimum values of ca. -2.3 MPa around 14:00 h (solar time).
Average total hydraulic conductance was 60 ± 6 mmol s-1 MPa-1,
presenting a slight decreasing trend as the season progressed. The
analysis of tree K components showed that it was higher on the
stem-leaf pathway (150 ± 50 mmol s-1 MPa-1), compared to the
root-stem component (100 ± 20 mmol s-1 MPa-1), which is in
agreement with literature reports for other fruit trees. A weak
hysteresis pattern in the daily relationship between whole-canopy
transpiration (weighted sunlit and shaded leaves) vs. y was observed,
suggesting that water storage within the tree is not a significant
component of sweet cherry water balance.Como un paso necesario para la comprensiĂłn de la extracciĂłn
de agua desde el suelo y las relaciones suelo-agua-planta, los
componentes de la conductancia hidrĂĄulica (K) en ĂĄrboles
adultos de cerezo ( Prunus avium L.) fue evaluada in situ con un
mĂ©todo basado en una analogĂa de la Ley de Ohm. En Junio de
2004, K fue determinada para ĂĄrboles
âBingâ/âGiselaÂź 5â de 10 años de
edad, a partir de mediciones simultĂĄneas de intercambio gaseoso
del follaje en forma integrada y potenciales hĂdricos (y) de hojas
individuales (soleadas y sombreadas) y del xilema. Los potenciales
hĂdricos de las hojas soleadas fueron menores que los de las hojas
sombreadas, alcanzando valores mĂnimos de ca.-2.3 MPa alrededor de
14:00 h (hora solar). La conductancia hidrĂĄulica promedio total
fue de 60 ± 6 mmol s-1 MPa-1, presentando una leve
disminuciĂłn en la medida que la temporada avanzĂł. El
anĂĄlisis de los componentes de la conductancia hidrĂĄulica
mostrĂł que Ă©sta fue mayor en la secciĂłn xilema-hoja (150
± 50 mmol s-1 MPa-1) y menor en el tramo raĂz-xilema (100
± 20 mmol s-1 MPa-1), lo que es concordante con estudios previos
en otros årboles frutales. Se observó un débil
patrón de histéresis en la relación diaria entre la
transpiraciĂłn total del ĂĄrbol (ponderando las hojas soleadas
y sombreadas) vs. y, lo que sugiere que el almacenamiento al interior
de los ĂĄrboles de cerezo no es un componente importante en su
balance hĂdrico
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