Adaptation of land management in the Mediterranean under scenarios of irrigation water use and availability

Integrating IPAT and CLUMondo Models to Assess the Impact of Carbon Peak on Land Use

China’s growth plans include a carbon emission peak policy, which is a restriction that indirectly impacts land use structure. In this study, we simulate different paths for achieving policy objectives, and explore the linkages between those paths and land use change. The IPAT model was used to simulate the carbon emissions generated from a natural development scenario, an ideal policy scenario, and a retributive carbon emission scenario in China from 2020 to 2030. The simulation results were incorporated into the CLUMondo model as a demand driver to simulate the land use change in 2030. The results show that carbon emission peak policy can somewhat reduce carbon emissions and increase building land in a regulated way. However, the policy may also lead to a short-term surge in carbon emissions, a reactive expansion of arable land and building land. This may reduce losses in economic development when carbon emissions are limited, but does not achieve the integration of social, economic, and ecological goals. This study links the carbon emission peak policy with land use change and provides a fresh perspective on the Chinese government’s carbon reduction policy.

Representing responses to climate change in spatial land system models

Modelling future change to land use and land cover is done as part of many local and global scenario environmental assessments. Nevertheless, there are still considerable challenges related to simulating land-use responses to climate change. Mostly, climate change is considered by changing the temperature and precipitation, affecting the spatial distribution and productivity of future land use and land cover as result of differential changes in growing conditions. Other climate change effects, such as changes in the water resources needed to support future cropland expansion and intensification, are often neglected. In this study, we demonstrate how including different types of responses to climate change influences the simulation of future changes to land use and land cover, and land management. We study the influence of including different climate change effects in land system modeling step by step. The results show that land system models need to include numerous simultaneous climate change effects, particularly when looking at adaptation options such as implementing irrigation. Otherwise, there is a risk of biased impact estimates leading either to under- or overestimation of the consequences of land use change, including land degradation. Spatial land system models therefore need to be developed accounting for a multitude of climate change impacts, uncertainties related to climate data, and an assessment of the sensitivity of the outcomes toward the decisions of modellers on representing climate change impacts.

Development of a groundwater contamination index based on the agricultural hazard and aquifer vulnerability: Application to Portugal

Reducing nitrate leaching may not result in a significant improvement of groundwater quality. The amount of nitrate reaching groundwater depends not only on the hazard related to agricultural activities but also on-site specific groundwater vulnerability. Using national databases and other compiled datasets, the agricultural hazard was calculated as the ratio of (i) the nitrate leached estimated from the N surplus, and (ii) the water surplus, a proxy of the percolating water below the root zone. By combining the hazard with a multi-parameter groundwater vulnerability, a spatially explicit groundwater contamination risk, developed for mainland Portugal, was computed for 1999 and 2009. Results show an increase from 8,800 to 82,679 ha of the territory rated with a very high contamination risk. The priority areas were successfully screened by the Index, coinciding with the current Vulnerable Zones, although additional hotspots were detected in southern Portugal. Percolation, including both irrigation activity and precipitation, was found to be a key driver for the groundwater contamination risk due to its opposite effects in the hazard and in the vulnerability. Reducing nitrogen leaching may be insufficient to reduce the risk of nitrate contamination if there is a relatively larger reduction in precipitation. This index is particularly useful when applied to contrasting situations of vulnerability and hazard, which require distinct mitigation measures to mitigate groundwater contamination.

Bacteria could help ectomycorrhizae establishment under climate variations

Rhizosphere microbiome is one of the main sources of plant protection against drought. Beneficial symbiotic microorganisms, such as ectomycorrhizal fungi (ECMF) and mycorrhiza helper bacteria (MHB), interact with each other for increasing or maintaining host plant fitness. This mutual support benefits all three partners and comprises a natural system for drought acclimation in plants. Cork oak (Quercus suber L.) tolerance to drought scenarios is widely known, but adaptation to climate changes has been a challenge for forest sustainability protection. In this work, ECMF and MHB communities from cork oak forests were cross-linked and correlated with climates. Cenococcum, Russula and Tuber were the most abundant ECMF capable of interacting with MHB (ECMF~MHB) genera in cork oak stands, while Bacillus, Burkholderia and Streptomyces were the most conspicuous MHB. Integrating all microbial data, two consortia Lactarius/Bacillaceae and Russula/Burkholderaceae have singled out but revealed a negative interaction with each other. Russula/Burkholderaceae might have an important role for cork oak forest sustainability in arid environments, which will be complemented by the lower drought adaptation of competitive Lactarius/Bacillaceae. These microbial consortia could play an essential role on cork oak forest resilience to upcoming climatic changes.

Assessing groundwater irrigation sustainability in the Euro-Mediterranean region with an integrated agro-hydrologic model

Abstract. We assess the sustainability of groundwater irrigation in the Euro-Mediterranean region. After analysing the available data on groundwater irrigation, we identify areas where irrigation causes groundwater depletion. To prevent the latter, we experiment with guidelines to restrict groundwater irrigation to sustainable levels, simulating beneficial and detrimental impacts in terms of improved environmental flow conditions and crop yield losses. To carry out these analyses, we apply the integrated model of water resources, irrigation and crop production LISFLOOD-EPIC. Crop growth is simulated accounting for atmospheric conditions and abiotic stress factors, including transpiration deficit. Four irrigation methods are modelled: drip, sprinkler, and intermittent and permanent flooding. Hydrologic and agricultural modules are dynamically coupled at the daily time scale through soil moisture, plant water uptake, and irrigation water abstraction and application. Water abstractions of other sectors are simulated based on requirement data. Water may be withdrawn from groundwater, rivers, lakes and reservoirs. As groundwater is abstracted to buffer the effects of drought, we use groundwater depletion to detect unsustainable water exploitation. We characterise reported data of annual groundwater abstractions for irrigation available at country and sub-national levels. Country data are the most complete, but their spatial resolution is often coarse. While the resolution of sub-national data is finer, their coverage is heterogeneous. Simulated and reported irrigation groundwater abstractions compare well in several areas, particularly in France, while some structural discrepancies emerge: simulated values tend to be larger than those reported, especially in southern Spain; and simulated inter-annual variability is significantly smaller than reported in some areas, most remarkably in Turkey. Potential causes of these discrepancies are simplified model assumptions influencing irrigation frequency and amounts; lack of high temporal and spatial resolution data on irrigated areas, and irrigation technologies and distribution; and possible unreported abstractions in areas where groundwater irrigation is significant. We identify areas undergoing groundwater depletion from model simulations. In the southern Iberian Peninsula, Greece, Middle East and northern Africa, most simulated depletion is caused by irrigation. In other Mediterranean areas, depletion is caused by all sectors combined. From well measurements of groundwater table depth in Spain, we find statistically significant decline rates affecting large areas of the south, thus in agreement with the model, but also areas in the north-eastern and central parts where model estimates detect no depletion. The comparison of model- and well-based depletion rates is limited by spatial scale differences and groundwater model assumptions, for which we suggest potential research directions. We design rules restricting irrigation groundwater abstraction to prevent groundwater depletion and minimise severe irrigation shortages. We optimise them and simulate their effects in the southern Iberian Peninsula. Irrigation restrictions cause crop yield reductions in groundwater-dependent irrigated areas, particularly in the Algarve and Segura river basin districts. At the same time, they positively impact environmental flows. This study shows the potential of integrated agro-hydrologic modelling for detecting water resources over-exploitation and exploring trade-offs between crop production, sustainable irrigation and ecosystem support.

Assessing Ecosystem Services Supplied by Agroecosystems in Mediterranean Europe: A Literature Review

Agricultural landscapes in the Mediterranean region may be considered as social-ecological systems that are important for biodiversity conservation whilst contributing to a wide range of ecosystem services. This literature review aims to identify the current state and biases of ecosystem service assessment in agroecosystems within the Mediterranean region, evaluate pressures impacting on agroecosystems and their services, and practices that promote ecosystem service synergies in Mediterranean agroecosystems. A total of 41 papers were selected for analysis from a set of 573 potentially relevant papers. Most of the selected papers focused on supporting, regulating and provisioning services, and mostly assessed ecosystem structure or services in the European Mediterranean context. Literature about benefits and values ascribed to by communities and stakeholders remain limited. Results presented here support the notion of multifunctional Mediterranean agroecosystems and multiple synergies were recorded in this review. Publications dealing with pressures that related to agricultural practices and demographic changes were in the majority and impact on different cropping systems. This review highlights the need to carry out integrated ecosystem service assessments that consider the multiple benefits derived from agroecosystems and which may be used to identify management practices that lead to the improvement of ecosystem services capacities and flows.

The Irrigation Cooling Effect as a Climate Regulation Service of Agroecosystems

Agroecosystems provide a range of benefits to society and the economy, which we call ecosystem services (ES). These services can be evaluated on the basis of environmental and socioeconomic indicators. The irrigation cooling effect (ICE), given its influence on the land surface temperature (LST), is an indicator of climate regulation services from agroecosystems. In this context, the objective of this study is to quantify the ICE in agroecosystems at the local scale. The agroecosystem of citrus cultivation in Campo de Cartagena (Murcia, Spain) is used as a case study. Once the LST was retrieved by remote sensing images for 216 plots, multivariate regression methods were used to identify the factors that explain ICE. The use of a geographically weighted regression (GWR) model is proposed, instead of ordinary least squares, as it offsets the spatial dependence and gives a better fit. The GWR explains 78% of the variability in the LST, by means of three variables: the vegetation index, the water index of the crop, and the altitude. Thus, the effects of the change in land use on the LST due to restrictions on the availability of water (up to 1.22 °C higher for rain-fed crops) are estimated. The trade-offs between ICE and the other ES are investigated by using the irrigation water required to reduce the temperature. This work shows the magnitude of the climate regulation service generated by irrigated citrus and enables its quantification in agroecosystems with similar characteristics.

Optimal water and land resource allocation in pastoral areas based on a water-land forage-livestock balance: a case study of Otog Front Banner, Inner Mongolia, China

Natural grasslands provide important land resources in pastoral areas, and greatly contribute to ecological functioning. Overgrazing and other unreasonable exploitations have led to the degradation and desertification of natural grasslands, exacerbating the forage-livestock imbalance. In areas suffering from water shortage, this imbalance gradually evolves into a water-land forage-livestock imbalance. In this study, a water-land forage-livestock balance-based model was developed to optimise the allocation of water, land, and forage resources in pastoral areas, while addressing economic and ecological benefits in a coupled manner. The model was applied in a case study of Otog Front Banner to simulate the comprehensive economic and ecological benefits to the development of water, land, and forage resources in different coupled allocations of artificial and natural grasslands. The results showed that as the duration of supplementary and barn feeding increased, local development was first constrained by the availability of natural grasslands and then by the availability of water resources. The optimal resource allocation in Otog Front Banner predicted for 2030 included a water consumption of 266,000,000 m³, an irrigation area of 43,000 ha, a natural grassland utilisation area of 684,700 ha, and a livestock farming scale of 1,188,500 sheep units.

New tools and approaches to promote soil and water bioengineering in the Mediterranean

Soil loss and erosion is a major environmental problem in the Mediterranean. Soil and water bioengineering uses plants and/or parts of plants along with inert material to create solutions to fulfill soil conservation objectives combined with an ecological rehabilitation approach. The ECOMED project developed novel approaches and tools to specialize the soil and water bioengineering sector within the Mediterranean. The first activity was the Sector Needs Analysis were the responses to an online questionnaire of 110 stakeholders from the region were analyzed. The main conclusion was the need to specialize the soil and water bioengineering sector in the Mediterranean. In addition, 21 soil and water bioengineering case studies in the Mediterranean were reviewed. Many works of this type are implemented in the region, but have flaws because of the lack of training material, design routines, protocols, specific to the region. The second activity developed New Design Routines and Protocols. Specifically, three protocols, one template and one plant database were developed for the region. Finally, in the Training Material activity, six educational modules along with a handbook (that contained modules, protocols, template and case studies) were developed. Overall the ECOMED project generated new and novel material and tools that were lacking in the region to enhance the specialization process of the soil and water bioengineering sector. These should increase the adoption of soil and water bioengineering techniques with better trained and new professionals as well as improve the work performance of these interventions.

Adaptations in irrigated agriculture in the Mediterranean region: an overview and spatial analysis of implemented strategies

In order to meet future food demand while sustainably managing available land and water resources, irrigated agriculture in semi-arid regions needs to adapt as a response to climate and socio-economic change. In this study, we focus on the Mediterranean region, a dynamic region, which is highly dependent on irrigated agriculture. We provide insight on adaptation strategies implemented on farm level, by doing a systematic review of studies in the region. Our analysis reports 286 implemented adaptations, on 124 different locations throughout the Mediterranean. Additionally, 142 drivers and 324 effects of adaptations were noted. We identified 31 adaptation strategies in 5 main categories: (1) water management, (2) sustainable resource management, (3) technological developments, (4) farm production practices, and (5) farm management. Strategies in the categories water management and farm production practices are most often implemented by farmers in the region. The main driver in the area is water scarcity and adaptations often affected water use and resources in addition to farm practices. Subsequently, we studied the spatial context of adaptations by analyzing the location factors of the five main strategies, using Geographic Information Systems and maximum entropy modeling. Our results show that farmers are more likely to adapt in less rural areas with lower poverty values and better market access, and in areas with higher temperatures and less rainfall. This demonstrates that both biophysical and socio-economic factors determine the context in which adaptations are implemented and that considerable spatial variability in the area exists.