Aleppo pine at risk: Climate impacts arrive decades earlier than projected

This photo shows Aleppo pine trees in Tzora, Israel, that died during a severe drought in May 2026. The trees with green tops are a different species, Mediterranean cypress, which survived the dry conditions. Credit: Prof. Tamir Klein

In 2020, our research published in New Phytologist showed how the height growth of Aleppo pine populations responded to climate gradients across the Mediterranean, and how these populations were expected to respond under future climate change based on decades of common-garden experiments. Since then, multiple studies on Pinus halepensis have documented diverse and often rapid growth and survival responses to recent climatic extremes.

Instead of conducting a traditional systematic review, we evaluated these new findings against our original projections developed six years earlier, testing explicit hypotheses in a new review published in Forest Ecology and Management. Our review reveals that several climate impacts originally predicted for midcentury are already occurring, highlighting an accelerated vulnerability of Mediterranean Aleppo pine forests.

The tested hypotheses were that climate change would reshape the growth of Pinus halepensis in predictable ways. Coastal forests would be more vulnerable than inland ones, dry sites more sensitive than wet sites, and range-edge populations more exposed than core regions. The result is a clear and consistent pattern: Across the Mediterranean, Aleppo pine forests are already experiencing the climate-driven growth declines that were originally forecast for midcentury.

Coastal forests show earlier and stronger declines

Several recent tree-ring studies confirm that coastal Aleppo pine populations are losing growth faster than inland ones. In Algeria, growth declines between 2013 and 2023 were significantly stronger in coastal forests than in continental montane sites. Similar patterns were observed in Italy, where coastal forests showed steeper reductions in earlywood growth and greater sensitivity to drought.

These findings match the 2020 projections, which predicted mild to moderate declines in coastal regions and relative stability inland. What is striking is not the direction of change, but its timing—declines expected decades from now are already visible.

Range-edge forests are under severe pressure

The study also highlights rapid changes at the edges of the species' distribution. In southern Spain, new species-distribution models show that range-edge populations are losing suitable habitat far earlier than expected. In Israel, natural regeneration at the hyperarid Yatir Forest has nearly collapsed, with almost no seedlings surviving beyond their first year. This mirrors earlier observations from provenance trials, where survival at Yatir was already low, but the new field evidence suggests that regeneration failure is accelerating.

Dry sites are reaching physiological limits

Across Greece, Spain and Israel, dry sites show the strongest declines. Tree-ring studies from Zakynthos and Samos reveal that mountain populations lose growth rapidly under drought, while valley populations, though initially more productive, also show sharp declines when rainfall drops. In eastern Spain, mortality reached up to 99% at the driest sites following an extreme drought year.

These observations align with the 2020 projections, which identified drying as the most critical risk factor for Aleppo pine. But again, the pace of change is faster than expected.

Even core regions are no longer buffered

Perhaps the most concerning finding is that core Mediterranean forests, previously thought to be relatively resilient, are also showing declines. In northeastern Spain, mortality reached 26%–44% in two core-range forests, despite projections of moderate growth increases. This mismatch suggests that extreme events, such as multiyear droughts, may be overwhelming the buffering capacity of these regions.

Ecotypes offer a path forward

Despite the worrying trends, the authors emphasize that forest-management options remain far from exhausted. One promising approach is the use of climate-adapted ecotypes that differ in growth, phenology and drought tolerance.

The 2020 study identified several ecotypes with strong growth performance under specific climatic conditions. For example, the DST ecotype, originating from Greece, shows high resilience under dry, semiarid conditions. The DSC ecotype performs well in cooler inland regions. Recent field trials in Spain confirm that selecting seed sources adapted to future climate conditions can significantly improve growth and survival.

Assisted migration and adaptive management

Assisted migration, namely, planting trees from regions that already experience the climate expected at the target site, is gaining traction. A recent study in eastern Spain found that climate-adapted seed sources increased height growth by up to 16% and diameter by up to 21%. Survival gains were modest, but still positive compared to local seed sources, which suffered substantial losses.

Other management strategies include thinning to reduce competition, improving soil moisture retention and diversifying forest structure to buffer against extreme events.

A faster-than-expected transition

Overall, the new review paints a clear picture: Climate change impacts on Mediterranean pine forests that were expected to unfold gradually are not a distant future scenario. They are unfolding now, and in many cases, faster than predicted. Yet the study also highlights a hopeful message. Informed, ecotype-based management and adaptive forestry practices can still help Mediterranean forests navigate the challenges ahead.

This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.

Publication details

Tamir Klein et al., Climate change effects on Mediterranean pine forests are faster than previously predicted, Forest Ecology and Management (2026). DOI: 10.1016/j.foreco.2026.124233

Who's behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

Theofania-Sotiria Patsiou is a researcher in plant ecology, evolution, and biogeography at the University of Bern. Her work examines climate–distribution interactions, ecological traits and ecotypic variation in Alpine and Mediterranean ecosystems. She has contributed key insights into Aleppo pine climate responses through common garden experiments, spatial growth projections, and synthesis studies. Her research aims to support evidence based management of climate vulnerable forests and species in general.

Tamir Klein is a research Professor at the Weizmann Institute of Science, Israel, studying forest ecology and tree physiology under climate change. His research focuses on carbon and water transport in and around trees in forests and plantations.

Jordi Voltas is Professor at the University of Lleida, Spain working on the ecophysiological and adaptive characterization of forest trees under Mediterranean conditions in the face of global change.

Citation: Aleppo pine at risk: Climate impacts arrive decades earlier than projected (2026, October 26) retrieved 26 October 2026 from https://phys.org/news/2026-10-aleppo-climate-impacts-decades-earlier.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.