Yatir (YTR), LTSER Northern Negev - Israel

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Yatir (YTR), LTSER Northern Negev

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General Site Description: 

The Yatir Research site was set up in 2000 at the center of the Yatir Forest, a 2'800 ha afforestation system of mainly P. halepensis trees, and is located on the southern end of the Hebron mountain range and at the northern edge of the Negev desert (31° 20’ N; 35° 3’ E; elevation 600 to 850 meters above sea level). Most of the area was planted during the 1960s-1970s. The site is located in the transition zone between the semi-arid and arid Mediterranean climates. Average air temperature for January and July is 10 and 25°C, respectively. Mean annual potential ET is 1600 mm, and mean annual precipitation is 285 mm. Only winter precipitation occurs in this region, creating a distinctive wet season (winter, December to March) and an extended dry season (summer, June to October), with short transition periods between them: a wetting season (autumn) and a drying season (spring). Research in the site mainly focuses on ecophysiology and ecohydrology, energy, carbon and water budgets, influence of stand density (through manipulation experiments), boundary layer dynamics and ecosystem interactions with the climate.

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General Characteristics, Purpose, History

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Purpose of Site : 

The Yatir Project, initiated in 2000, aims to focus on the complex impact of land use changes, such as afforestation, on carbon sequestration potential, surface temperature (energy budget), and water yield (the difference between precipitation and loss by evapotranspiration). Understanding these aspects and the unavoidable tradeoffs among them are often neglected, especially in the semi-arid region. But their knowledge should be used as a critical tool in formulating national and regional water and carbon management policies. Quantitative knowledge of these tradeoffs should also help in better understanding biosphere-atmosphere interactions on the global scale. Land use changes in Israel (from extensive tree cover ~10,000 years ago to today's intensive agriculture) significantly altered water yield. The main consequences are increases in runoff, contributing to floods, erosion and loss of fertile soils. Evapotranspiration provides the driving force for forest growth and carbon sequestration (coupled with other factors). Using the Yatir forest as a case study, we have demonstrated that the semi-arid zone has, in fact, greater potential than initially expected for carbon sequestration. In addition to the obvious tradeoffs between water yield and carbon sequestration, afforestation in the semi-arid region also has significant effects on surface temperatures. On sufficiently large scales, such changes in surface energy budget can influence local climate. Changes in forest cover due to climate change or human activities, have therefore complex but important consequences for water, carbon and the local environment that are poorly understood at present. Such changes could feed-back on the atmosphere and climate system. The aim of the Yatir site is to significantly advance our knowledge on this front in a typical semi-arid environment.

History of Site: 

The first trees were planted in 1960s-1970s by the Jewish National Fund (JNF/קק"ל). It is named after an ancient Levite city within its territory, Yatir (Book of Joshua 21:13-14). Millions of trees have been planted, mostly coniferous trees - Aleppo Pine and Cypress, but also some broad-leafed trees, e.g. Eucalyptus and Acacia, as well as vineyards and various shrubs, and the forest is still being extended through JNF plantations as of 2016. Yatir Forest has changed the arid landscape of the northern Negev, halting the desertification on the heights northeast of Beersheba.

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Latitude: 31.344860000000
Longitude: 35.052000000000