Flavio Lupia1, Luca Fraschetti1, Daniela Storti1 e Angelo Libertà2
1 CREA – Research Centre for Policies and Bioeconomy, Roma, Italy. 2 AlmavivA S.p.A. – Agriculture and Environment Practice, Roma, Italy. * flavio.lupia@crea.gov.it
Abstract
The Rural Development Framework is supporting farmers in areas affected by natural constraints (i.e. climate, morphology and soil) to counterbalance negative phenomena such as land abandonment, desertification, etc..
The designation of the new Areas with Natural Constraints (ANCs) is being carried out by EU Member States (Reg. (EU) No. 1305/2013). Three biophysical criteria (Climate, Soil and Terrain) are used followed by a fine-tuning process with indicators to assess whether constraints in a given area influence or not agricultural production. Indications on the procedures are given through guidelines prepared by European Commission’s Joint Research Centre.
We report on the Italian approach to delineate ANCs with the sole climatic constraint expressed by the three criteria: Dryness, Length of growing period and Thermal-time sum. Climatic criteria are calculated on a 10 km grid by spatializing daily meteorological time series from 1981 to 2010 stored in the National Agricultural Information System (SIAN). Then, criteria are downscaled to a finer grid (500 m) to be reported over agricultural areas located within municipalities.
Keywords
Areas with natural constraints, ANCs, agriculture, biophysical criteria, agro-meteorological data Parole chiave
Aree con vincoli naturali, ANC, agricoltura, criteri biofisici, dati agrometeorologici Introduction
The regime of the less-favoured areas is an important component of the Common Agricultural Policy, which aims to compensate the natural disparities among the different agricultural regions of the European Union. It is a useful support tool that provides a compensatory allowance to incentivize agricultural activities in mountainous and/or less developed areas subject to depopulation.
In the previous programming period (2007-2013), the resources provided for this purpose, at community level, amount to 15.2 billion euro, about 16% of the total expenditure disbursed by the European Agricultural Fund for Rural Development.
The rural development regulation in force in the current programming phase (2014-2020), without prejudice to the definition of the other categories of disadvantaged areas, has put on the agenda the revision process of the intermediate areas, perfecting the model to be followed for the delimitation of the areas called "Areas with Natural Constraints" (ANCs).
The reform is based on objective and homogeneous parameters of a biophysical nature, referring to climate, soil and morphology, and are defined in the context of Annex III of the EU regulation n. 1305/2013 with the scientific support of the European Commission’s Joint Research Centre (JRC) and experts from each Member State.
In the following sections we report the Italian approach for the computation of one of the biophysical criteria, climate, by using the available national datasets and following the guidelines prepared by JRC.
Materials and Methods Definition of climatic criteria
Area with Natural Constraints (ANCs) due to climatic conditions were defined by computing three distinct criteria: Dryness (DRY), Length of growing period (LGP) and Thermal-time sum (THS), according to the specific definitions reported in the JRC guidelines (Terres et al., 2016). Criteria are related to basic climatic characteristics deemed relevant to identify agricultural suitable lands for the European territory. Scientific grounds are related to the “problem-land approach” (FAO, 1990) where thresholds for each criterion are defined by literature and expert’s judgement. Climatic criteria are considered in terms of probability of exceedance by 20% of the established thresholds to overcome any issue related to inter-annual variation of the length of the growing season.
DRY is a limiting factor for crops when water availability is reduced by low precipitation and high evaporation. The ratio between the annual precipitation (P) and the potential evapotranspiration (PET) is computed to set a threshold for the severely limiting dryness condition: P/PET <= 0.5.
LGP and THS are the criteria to assess the low temperature limitation for European agriculture due to the expected impacts on the normal crop development.
LGP is defined by the number of days having daily average temperature greater than 5°C.
THS, in degree-days (°Cd), is computed for the growing period and defined by accumulated daily average temperature greater than 5°C.
Low temperature is a strong constraint to crop development when one of the above criteria exceed the established thresholds: LGP<=180 days; THS<= 1500°Cd.
Constrained areas are identified by computing each criterion for every year in the time series and by verifying whether the number of years exceed the 20% of the time series.
Dataset of meteorological variables
The meteorological variables required to compute climatic criteria were extracted from the National Agricultural Information System (SIAN). Temperature and precipitations were available as gridded daily time series for the period 1981-2010 for 3193 regular cells of 10 km covering the Italian territory (Rete Rurale Nazionale, 2018). Daily values of PET were computed for each cell with the Penman-Monteith equation.
The length of the time series follows the World Meteorological Organisation recommendations to minimise inter-annual variations and anomalies.
Gridded data result from the processing of measured daily meteorological variables belonging to different meteorological networks (nationals and regionals) with an average of 107 active stations between 1981 and 2010. Data validation was performed by SIAN through statistical algorithms (i.e. values checking against the climatic mean of the station, the time period and measures from nearby stations).
Daily measurements from the active stations were used for the geostatistical estimate of the values for each one of the 3193 cells. Ordinary Kriging (Cressie, 1989) was applied to estimate the total daily precipitation while non-stationary Cokriging with external drift (Chilés e Delfiner 1999) was used to compute variables showing geographical trends (i.e. maximum and minimum temperature, humidity, and wind speed). Cokriging allowed to estimate meteorological variables coherently with daily extreme values (e.g. minimum temperature must be less than maximum temperature) and to improve the estimation (i.e. when one of the two temperature values was missing). The use of Cokriging enabled the integration of the daily measured data observed with another dataset reproducing the main physical laws, which explain the spatio-temporal dynamics of atmosphere, physiography and morphology. This dataset is known with good precision overall Italian territory. It represents the deterministic component of the meteorological field from which the spatial gradients of the meteorological variables are derived. The external drift defined on the 3193 grid cells is elaborated by the DALAM
hydrostatic meteorological model (Data Assimilation Limited Area Model).
The spatial structure of the meteorological variables (variograms) was detected using the daily data observed from 1981 to 2010. Variograms modelling was performed at monthly level for two geographical areas:
• Northern Italy – variograms were computed for the geographical directions E-W, NE-SW, N-S and SE-NW, with the EW coincident with the orientation of Padana Plain and Alps);
• Central-Southern Italy – variograms were calculated for the geographical directions EW 40°, EW 85°, EW 130° and EW 175°, where EW 130° coincide with the Apennines orientation.
Assessment of the accuracy of the geostatistical estimators was carried out by using an independent dataset of 83 meteorological station having a uniform distribution across Italy (Esposito et al., 2015). Daily meteorological values from the independent stations were compared with the estimated values of the grid cells containing the corresponding stations (external validation). Statistical indicators were used to assess the accuracy: MAE (mean absolute error) and CRM (coefficient of residual mass). MAE resulted in a mean error of ±2°C for the estimated maximum and minimum daily temperature and ±2.4 mm for the total daily precipitation. CRM indicated a slight underestimation of the maximum daily temperatures and an overestimation of daily minimum temperatures. These errors tend to be compensated when the mean daily temperature is computed.
Computation of climatic criteria
The estimated meteorological time series were used to calculate the gridded climatic criteria. For each cell, the frequency of occurrence of the three criteria was calculated as percentage of unfavourable years over the total number of years. Cells resulting with a percentage greater than 20% were classified constrained by the corresponding criterion with a binary system (1: constrained; 0: not constrained). Agricultural areas were localized on a 500 m (25 ha) grid with the AGRIT program dataset, the point spatial sampling survey used to estimate Italian agricultural land use statistics. Land use data were sampled on orthophotos at 1:10,000 scale (AGEA Refresh project). Grid cells are compatible with the size of agricultural areas and the spatial extent of administrative units (municipalities). In fact, the grid has 1,206,000 cells covering the 8,046 Italian municipalities.
Climatic criteria were finally reported on the agricultural areas by downscaling data from the 10 km to the 500 m grid. The finer grid allows to report, on average, climatic criteria with 150 cells per municipality. Differences in temperature and precipitation over distances less than 500 m are generally negligible in Italian agricultural areas since their modelling is not possible by a meteorological network whose average distance between stations is greater than 10 km.
Results and Discussion
Figure 1 depicts the distribution of 500 m grid cells with agricultural areas constrained by the three climatic criteria. Cells are overlaid over the administrative boundaries of the municipalities. Constrained areas by climatic criteria are clearly concentrated within the two latitudinal extremes.
Fig.1 – Grid cells (500 m) affected by the three climatic constraints superimposed over municipalities boundaries. From top to bottom: Thermal-time sum (THS), Length of growing period (LGP) and Dryness (DRY).
Fig. 1: Rappresentazione dei tre vincoli climatici con la griglia a 500 m sovrapposta sui confini comunali. Dall'alto in basso: Tempo termico totale (THS); Durata del periodo vegetativo (LGP) e Siccità (DRY)
Northern mountainous areas are affected by the low temperature criteria (LGP and THS). On the other hand, as expected, Southern regions undergo limitations for agriculture mainly determined by dryness conditions (DRY).
Conclusions
The recent European regulation has laid down that areas affected by natural constraints for agriculture (ANCs) need to be delimited by Member States with biophysical criteria. Our paper describe the Italian approach followed for the computation of one of the criteria: climate. Results of the effect of the climatic constraints for agriculture are reported at grid level and mapped.
Next steps are in progress and will provide the delimitation of ANCs based on the remaining criteria: soil and terrain slope.
Final classification will integrate the tree criteria and will classify municipalities as ANC if the relative agricultural area is affected at least by a single criterion for a share greater or equal to 60%. Later on ANCs determined by biophysical criteria will be revised by a further process named “fine-tuning” where additional criteria are considered. With this final step, it will be assessed, at municipality level, whether natural constraints, which ANCs support aims to compensate, have been offset by human intervention and/or technical progress.
References
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Acknowledgements
This study was supported by the Programma Rete Rurale Nazionale 2014-2020 – Piano Biennale 2017/2018 – Scheda progetto 18.1.