Are treelines advancing? A global meta-analysis of treeline response to climate warming

• Published in: Ecology letters Vol. 12; no. 10; pp. 1040 - 1049
• Main Authors: Harsch, Melanie A, Hulme, Philip E, McGlone, Matt S, Duncan, Richard P
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.10.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Abrupt; advance; altitude; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Climate; Climate change; Climatology. Bioclimatology. Climate change; data collection; Databases, Factual; diffuse; Earth, ocean, space; Ecosystems; Exact sciences and technology; External geophysics; forest dynamics; Fundamental and applied biological sciences. Psychology; General aspects; Geography; global meta-analysis; Global warming; Greenhouse Effect; growth & development; krummholz; Latitude; Meta-analysis; Meteorology; physiology; Plant growth; Plant populations; Population Density; Population Dynamics; Temperature; Transition zone; Treeline; Trees; Trees - growth & development; Trees - physiology; Warming; Temperature; global meta-analysis; krummholz; forest dynamics; Vegetation dynamics; diffuse; Abrupt; Metaanalysis; advance; Dynamical climatology; Climate change; Treeline
• ISSN: 1461-023X; 1461-0248; 1461-0248
• DOI: 10.1111/j.1461-0248.2009.01355.x

Treelines are temperature sensitive transition zones that are expected to respond to climate warming by advancing beyond their current position. Response to climate warming over the last century, however, has been mixed, with some treelines showing evidence of recruitment at higher altitudes and/or latitudes (advance) whereas others reveal no marked change in the upper limit of tree establishment. To explore this variation, we analysed a global dataset of 166 sites for which treeline dynamics had been recorded since 1900 AD. Advance was recorded at 52% of sites with only 1% reporting treeline recession. Treelines that experienced strong winter warming were more likely to have advanced, and treelines with a diffuse form were more likely to have advanced than those with an abrupt or krummholz form. Diffuse treelines may be more responsive to warming because they are more strongly growth limited, whereas other treeline forms may be subject to additional constraints.