the GlobalChangeBiology blog

We quantified the photosynthetically active radiation (PAR) interception in a high-density (HD) and a super high-density (SHD) or hedgerow olive system, by measuring the PAR transmitted under the canopy along transects at increasing distance from the tree rows. Transmitted PAR was measured every minute, then cumulated over the day and the season. The frequencies of the different PAR levels occurring during the day were calculated. SHD intercepted significantly but slightly less overall PAR than HD (0.57 ± 0.002 vs. 0.62 ± 0.03 of the PAR incident above the canopy) but had a much greater spatial variability of transmitted PAR (0.21 under the tree row, up to 0.59 in the alley center), compared to HD (range: 0.34–0.43). This corresponded to greater variability in the frequencies of daily PAR values, with the more shaded positions receiving greater frequencies of low PAR values. The much lower PAR level under the tree row in SHD, compared to any position in HD, implies greater self-shading...

Outbreaks of a plant disease in a landscape can be meaningfully modelled using networks with nodes representing individual crop-fields, and edges representing potential infection pathways between them. Their spatial structure, which resembles that of a regular lattice, makes such networks fairly robust against epidemics. Yet, it is well-known how the addition of a few shortcuts can turn robust regular lattices into vulnerable ‘small world’ networks. Although the relevance of this phenomenon has been shown theoretically for networks with nodes corresponding to individual host plants, its real-world implications at a larger scale (i.e. in networks with nodes representing crop fields or other plantations) remain elusive. Focusing on realistic spatial networks connecting olive orchards in Andalusia (Southern Spain), the world’s leading olive producer, we show how even very small probabilities of long distance dispersal of infectious vectors result in a small-world effect that dramatically ...

MED-GOLD ( Turning climate-related information into added value for traditional MEDiterranean Grape, OLive, and Durum wheat food systems ) will demonstrate the proof-of-concept for climate services in the agriculture sector by developing case studies for three hallmarks of the Mediterranean food system: grapes, olives, and durum wheat.  Agriculture is primarily climate-driven and hence highly vulnerable to climate variability and change. Evidence suggests that the Mediterranean region is under immediate threat of shifting climate patterns and the associated ecological, economic and social effects. Developing a capacity to turn the increasingly big climate-related data into tailored climate services that can inform decision-making in agriculture is, therefore, a priority both in Europe and worldwide. The long-term goal of this project is to make European agriculture and food systems more competitive, resilient, and efficient in the face of climate change, by using climate serv...

Exotic species that invade new areas cause economic loss annually nearly tenfold that of natural disasters. The economic impact of such biological invasions has been considerable also in agriculture, with many major agricultural pests being invasive species, which number is expected to increase given the combined action of climate warming and globalization, particularly in the Mediterranean Basin. This region is rich in natural and agricultural biodiversity but also considerably vulnerable to biological invasions that threaten key elements of Mediterranean agro-biodiversity such as the traditional perennial crops grape and olive. Currently, most major threats to grape and olive culture are invasive species - often vector borne diseases so serious that the only control method is removal and destruction of infected crop plants. However, how to assess the potential impact of such invasive threats, and hence how to manage them, remains an unresolved and largely unexplored problem. Gaps exi...

Inability to determine reliably the direction and magnitude of change in natural and agro-ecosystems due to climate change poses considerable challenge to their management. Olive is an ancient ubiquitous crop having considerable ecological and socioeconomic importance in the Mediterranean Basin. We assess the ecological and economic impact of projected 1.8 °C climate warming on olive and its obligate pest, the olive fly. This level of climate warming will have varying impact on olive yield and fly infestation levels across the Mediterranean Basin, and result in economic winners and losers. The analysis predicts areas of decreased profitability that will increase the risk of abandonment of small farms in marginal areas critical to soil and biodiversity conservation and to fire risk reduction. Ponti L., Gutierrez A.P., Ruti P.M., Dell’Aquila A., 2014. Fine scale ecological and economic assessment of climate change on olive in the Mediterranean Basin reveals winners and losers. Procee...

Olive is of major eco-social importance for the desertification-prone Mediterranean Basin, a climate change and biodiversity hotspot of global relevance where remarkable climate change is expected over the next few decades with unknown ecosystem impacts. However, climate impact assessments have long been constrained by a narrow methodological basis (ecological niche models, ENMs) that is correlative and hence largely omits key impact drivers such as trophic interactions and the effect of water availability. To bridge this gap, mechanistic approaches such as physiologically-based weather-driven demographic models (PBDMs) may be used as they embed by design both the biology of trophic interactions and a mechanistic representation of soil water balance. Here we report progress towards assessing climate effects on olive culture across the Mediterranean region using mechanistic PBDMs that project regionally the multitrophic population dynamics of olive and olive fly as affected by daily wea...

The GlobalChangeBiology project is part of the Joint Programming Initiative on Agriculture, Food Security and Climate Change ( FACCE – JPI ) funded by the European Union under the 7th Framework Program. The goal of FACCE – JPI is to achieve, support and promote integration, alignment and joint implementation of national resources under a common research and innovation strategy to address the diverse challenges in agriculture, food security and climate change. Partnering MACSUR , the first pilot action of FACCE – JPI that will start officially in June 2012 (see first newsletter ), the GlobalChangeBiology project will provide case studies on grape and olive systems in the Mediterranean Basin. The MACSUR project is a knowledge hub that brings together 73 research groups from across Europe and will provide a detailed climate change risk assessment for European agriculture and food security, in collaboration with international projects including the GlobalChangeBiology project . As...

In the Mediterranean Basin, major islands including Sardinia are considered particularly vulnerable to global warming and desertification. We used a physiologically based demographic model (PBDM) of olive and olive fly to analyze in detail this plant-pest system in Sardinia under observed weather (ten years of daily data from 48 locations), three climate warming scenarios (increases of 1, 2 and 3 °C in average daily temperature), and a 105-year climate model scenario for the Alghero (e.g. 1951-2055). GRASS GIS was used to map model predictions, and model calibration with field bloom date data was performed to increase simulation accuracy of olive flowering predictions under climate change. As climate warms, the range of olive is predicted to expand to higher altitudes and consolidate elsewhere, especially in coastal areas. The range of olive fly will extend into previously unfavorable cold areas, but will contract in warm inland lowlands where temperatures approach its upper thermal li...

Climate change will make the Mediterranean Basin vulnerable to desertification, and this will affect many species such as olive in largely unknown ways. Olive is the base of a tri-trophic food web that includes pest, disease and their natural enemy species, each of which will be affected differently by climate change. The effects of extant weather and climate change scenarios on the tri-trophic interactions can be examined using biologically-rich physiologically-based demographic models developed from field and laboratory data. Studies from Sardinia, Italy and California show how the same model can be applied to these areas, and by inference, to other areas of the Mediterranean basin and elsewhere globally. Specifically, the model enables the examination of climate change on the range of olive and olive fly. The effect of climate change on natural enemies are illustrated using the olive scale/parasitoid interactions. The same system can also be used to examine the distribution and abu...

The Mediterranean Basin is expected to be particularly vulnerable to climate change including pronounced climate warming and desertification. Olive ( Olea europaea ) is of eco-social importance in the Mediterranean where it was domesticated, and it is also considered a sensitive climate indicator. This crop and its major pest, the olive fly Bactrocera oleae are a suitable model system to study Mediterranean climate. A weather-driven physiologically-based demographic model (PBDM) of olive and olive fly ( http://cnr.berkeley.edu/casas/ ) is being used to analyze this plant-pest system in the Mediterranean region based on ERA-40 weather data ( http://www.ecmwf.int/ ) downscaled via the regional climate model RegCM3 coupled to the MIT ocean model. PBDM predictions are mapped with the open source GIS GRASS ( http://grass.osgeo.org/ ). Ponti L., Gutierrez A.P., Ruti P.M., 2009. The olive– Bactrocera oleae system in the Mediterranean Basin: a physiologically based analysis driven by the...

Analytical tools that provide a synthesis of ecological data are increasingly needed to design and maintain sustainable agroecosystems increasingly disrupted by global change in the form of agro-technical inputs, invasive species, and climate change. This is particularly relevant to the Mediterranean Basin, a climate change hot-spot already threatened by local environmental changes including desertification. The project will provide important tools for summarizing, managing, and analyzing ecological data in agricultural systems to address global change effects using grape and olive as model systems. The project will integrate weather driven physiologically based Ecosystem Modelling (EM) and Geographic Information Systems (GIS) to derive a dynamic understanding of complex agricultural systems in the face of global change including climate warming. Multivariate analyses will be used to summarize the main effect of model predictions in a space and time independent way to provide a solid b...