Impact of residential settlements on the life supporting capacity of Har HaNegev arid environment
Lead Author: Prof. Moshe Shachak (Ben Gurion University of the Negev)
Contributors: Arnon Karnieli (BGU), Daniel Orenstein (Technion - Israel Institute of Technology), Ehud Meron (BGU), Yehoshua Shkedy (Israel Nature and Parks Authority), Asaf Tsoar (INPA), Shayli Dor-Haim (BGU), Noa Ohana-Levi (BGU), Miri Tsalyuk (INPA).
Dryland ecosystems worldwide are facing challenges of adaptation and reorganization in response to anthropogenic climate and land use changes [1-3]. While the consequences of human residential development as a major land use change on ecological systems have been studied [4-6], the effect of settlements on the fragile arid environment on the various levels of ecological organization and landscape scales is not well understood.
Israel is one of the densest countries in the world, with the largest birth rate among the developed countries . The fast population growth rate in the country drives an increasing pressure for rapid residential development. The Negev, the southern arid part of Israel, is the largest land resource of the country, and government policy encourages redirecting growth to this region. Therefore, residential development is predicted to expand to this area; it is crucial to understand the effect of such settlement on the ecological integrity of the system.
The Negev Highland (Har HaNegev, HN) is an arid environment limited by water and nutrient availability. It has a mean annual rainfall of 80-100 mm and a mean annual temperature of 18°C (-4°C - 40°C) . Patterns of precipitation and redistribution of rainfall by runoff water drives ecosystem structure and functions such as primary and secondary productivity, decomposition and biodiversity. The system is characterized by high topographic, geologic, geomorphic, and pedologic diversity (geodiversity). The geodiversity further interacts with the biodiversity to create unique Hydro-Geo-Eco-Systems. HN has impressive biodiversity with many unique and endemic species. The high abiotic (geologic) and biotic diversity of the system provide diverse ecosystem services that have attracted human settlement in HN since early times. In the HN Protected Area (HNPA), the priority ecosystem services are habitat services for unique dryland species and the existence value of biodiversity, which also supports a broad array of cultural services, including educational activities, research, recreation, and tourism.
HNPA covers an area of about 1107 km2. Within the HNPA are three small towns, 13 rural communities, and about 30 homesteads. The homesteads make a living from small scale farming, wineries, grazing, and tourism . The Negev is also home for semi-pastoral Bedouins. In HNPA, the Bedouin live in small family communities, and their economic activities include sheep, goat and camel herding, manual jobs and tourism. While all these types of settlements have considerable effect on the biodiversity and the ecological integrity of the HNPA, these effects and ways to mitigate them are not well understood [9-13].
HNPA experiences multiple competing land uses including residence, mining, agriculture, grazing, tourism, and recreation. Army training, which is also a prominent activity in and around the PA, has a considerable ecological impact. The multitude of competing land uses, particularly residential development, are the most pressing driver of change to the ecological integrity of HN. Urban and rural development imposes pulse and press changes on HN, depending on their intensity and temporal characteristics . The pulse event is the establishment of a new residential community, while the press is the continuous interactions between the settlement and the biophysical environment. Disturbances resulting from residential development radiates beyond the actual site of activity, and includes additional land cover change, pollution, noise, and artificial lighting. Infrastructures and roads connecting the settlements, and their waste output, e.g. sewage, solid waste, and animal manure, increase their potential impact. Economic activities further drive land use change around settlement.
Earth observation (EO) systems are especially useful for understanding the effect of land use pressure on the ecological integrity of HN. A major goal of HNPA project is to develop tools for using EO in arid environment in order to track changes in biodiversity, ecosystem dynamics, and ecosystem services provisioning, driven by land use changes.
The goal of the HNPA team within the ECOPOTENTIAL project was to understand the effects of residential development on the life supporting capability of HNPA. The team aimed to produce research that could provide evidence to guide future development, and guide local regional planning of settlements in the area. In addition, better understanding of settlement-landscape relationship was through to contribute to improving the management of protected areas and biodiversity.
In the spirit of ECOPOTENTIAL, three research projects were initiated following collaborative work with one of the region's primary land-use management stakeholders - The Israel Nature and Parks Authority, who is responsible for managing those parts of the HNPA that are designated nature reserves or national parks, and for protecting Israel's biodiversity. Two of the projects [15-16] focused on applying EO tools for assessing the impact of residential development on ecosystem service provision in the HNPA. The third project surveyed the landscape aesthetic preferences of residents and visitors to the HNPA with regard to various forms of preservation and development.
The first study assessed the local and watershed-scale impact of water harvesting systems (e.g. terraces, small earthen dams) on soil quality (tested in-situ) and vegetative productive (measured using remotely sensed data). Such water harvesting systems were a central component of ancient agricultural communities in the Negev Highland, and are today proposed as tools to provide ecosystem services (e.g. fodder, fuel wood, shade) for local residents and visitors. Results from field studies and modelling [18-19] suggest that the addition of water harvesting systems, in the form of small water catchments within the wadis of the HNPA, raises soil fertility, moisture and primary productivity at the local scale, without negatively impacting these variables at the watershed scale. While their impact on biodiversity remains to be studied, the researchers recommend considering such water catchments as tools to raise overall primary productivity in these water-limited systems.
In the second study, the direct and indirect impacts of residential development in the HNPA were assessed with regard to vegetative cover as measure with EO data. This study provided empirical evidence that proximity to populated areas is a major driver of vegetative cover, which was the third most important determinant of vegetation productivity patterns after the environmental characteristics of elevation and slope. Vegetative cover generally increased in close proximity to human communities (partly due to farming near these communities) and then declined rapidly after a threshold difference. This decline was most extreme for pastoral communities with their grazing activities. The study further showed that establishment and management of protected areas contributes to a rise in vegetative productivity, primarily by limiting domestic grazing within its boundaries.
In the final landscape aesthetics research, 200+ residents and visitors to the HNPA were surveyed regarding which of 16 typical Negev Highland landscapes they found most visually appealing. As a general trend, respondents preferred all landscapes that featured a significant amount of vegetation within, whether they were agricultural fields or small groves of planted trees. Infrastructures, including roads, homes, and electrical wires, as well as more barren (yet arguably more natural) landscapes, were less preferred. The study also tested responses against various demographic variables and environmental values indices.
Overall, the ECOPOTENTIAL project in the Negev Highland demonstrated the utility of EO data for conducting policy-relevant research on ecosystems a large spatial scales. Residential and associated development in the Negev Highland has had diverse impacts on a variety of ecosystem functions - some of these can be detrimental to the provision of ecosystem services and some beneficial. But most development, as shown in this research, will often be ambiguous, affecting some ecosystem services positively and others negatively. As such, land use managers must balance the tradeoffs inherent in residential development, working to assure long-term ecosystem integrity under increasing pressure of a growing population.
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Related ECOPOTENTIAL publications
15. Paz-Kagan, T., Ohana-Levi, N., Shachak, M., Zaady, E. & Karnieli, A. (2017) Ecosystem effects of integrating human-made runoff-harvesting systems into natural dryland watersheds, Journal of Arid Environments, Volume 147, 2017, Pages 133-143, ISSN 0140-1963, https://doi.org/10.1016/j.jaridenv.2017.07.015.
16. Qi H., Paz-Kagan T., Karnieli A. and Li S., 2017, Linear Multi-Task Learning for Predicting Soil Properties Using Field Spectroscopy., Remote Sensing, doi:10.3390/rs9111099.
17. Orenstein, D.E., Porat, I., & Tsalyuk, M. (2018) Green or Brown, Built or Open? Correlations between landscape preferences in an arid ecosystem, underlying environmental values and demographic characteristics. June, 2018. 5th European Congress of Conservation Biology. Jyvskyl, Finland. DOI: 10.17011/conference/eccb2018/107291
18. Ohana-Levi, N., Paz-Kagan, T., Panov, N., Peeters, A., Tsoar, A. & Karnieli, A. (2019) Time series analysis of vegetation-cover response to environmental factors and residential development in a dryland region, GIScience & Remote Sensing, 56:3, 362-387, DOI: 10.1080/15481603.2018.1519093
19. Dor-Haim, S. et al. 2019. Studies of ecosystem structure and function of ancient terraces in the Negev Highlands as a tool for rehabilitation program to increase ecosystem service. Final report. Israel Ministry of Science and Technology;
20. M. Silver, A. Tiwari & A. Karnieli, 2019, Identifying vegetation in arid regions using object-based image analysis with RGB-only aerial imagery, Remote Sensing, https://doi.org/10.3390/rs11192308
21. T. Paz-Kagan, N. DeMalach, E. Zaady, M. Shachak, 2019, Resource redistribution effects on annual plant communities in a runoff harvesting system in dryland, Journal of Arid Environments, https://doi.org/10.1016/j.jaridenv.2019.05.012
22. Hezi Yizhaq, Moshe Shachak, Ehud Meron, 2020. A model study of terraced riverbeds as novel ecosystems, Scientific Reports, 10.1038/s41598-020-60706-y.
This short description of the EcoPotential work conducted in the Har HaNegev Protected Area is featured in an interactive on-line story map which can be found at the following link
Click here to download the storyline presentation.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 641762.
Last update: March 2020