Dorman, M., Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Perevolotsky, A., Department of Agronomy and Natural Resources, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
Sarris, D., Open University of Cyprus, Latsia, Nicosia, Cyprus, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus, Division of Plant Biology, Department of Biology, University of Patras, Patras, Greece
Svoray, T., Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer-Sheva, Israel

We investigated forest responses to global warming by observing: (1) planted Pinus halepensis forests, (2) an aridity gradient—with annual precipitation (P) ranging from ~300 to ~700 mm, and (3) periods of wet and dry climate that included the driest period during at least the last 110 years. We examined: (1) how the length of climatic integration periods to which trees are most responsive varies in space and time, (2) the extent to which competition modulates growth decline during drought (2011) and subsequent recovery (2012) years. The temporal scale of rainfall that was most influential on growth shortened in progressing southward, and in the drier than in the wetter period. Long-term underground water storage, as reflected in the relationship of growth to multiple-year rainfall, remained significant up to the point where P ≈ 500 mm. Under drier conditions (P < 500 mm) in both space and time, influential rainfall scales shortened, probably reflecting a diminishing role of water storage. These drier locations are the first from which the species would be likely to retreat if global warming intensified. Competition appeared to set an upper limit to growth, while growth variation among individual trees increased as competition-intensity decreased. That upper limit increased in 2012 compared with 2011. The observed insensitivity of slow-growing trees to competition implies that mortality risk may be density independent, when even any potential for higher soil moisture availability in open stands is lost to evapotranspiration before it can benefit tree growth. © 2015, Springer-Verlag Berlin Heidelberg.