Milder winters would alter patterns of freezing damage for epiphytic lichens from the trans-Himalayas

Description

This is the supporting dataset to the paper Worthy et al. 2024 published in Scientific Reports. All methods used to produce the data are described in the methods section of the associated manuscript. A key is provided within each dataset to explain the headings and nature of each column of the data. ABSTRACT Trans-Himalayan winters are projected to become milder, with shifting precipitation patterns and freeze-thaw cycles; changing stressors for their lichen communities. Lichens from Antarctica and high latitudes are cryoresistant when dry, but susceptible to cell damage if frozen when wet, or subjected to repeated freeze-thaw events. Little is known regarding cryoresistance in high-elevation, mid-latitude lichens. We collected thalli of nine species of epiphytic lichenized fungi, from three regions of the trans-Himalayas; at ≈ 4000 m, 3400 m and 2400 m elevation. We subjected thalli to differing freezing (continuous -18°C and -36°C or freeze-thaw cycles in natural daylight) and moisture conditions. Even dry thalli suffered some damage. Frozen wet thalli had greater chlorophyll degradation and reduced chlorophyll content. There were no clear elevational trends in freeze-thaw susceptibility: it caused more damage than continuous freezing. The most freeze-thaw resilient lichens were Dolichousnea longissima (from 4000 m) and Usnea florida (from 2400 m). However, species from coldest sites were most resilient to extreme freezing. Under predicted climate change conditions these sites would experience fewer annual freeze-thaw cycles, annual sub-zero days and frost days. Reduced freezing constraints might allow range expansion of mid-elevation lichens, but increase competitive pressures and temperature stressors impacting high-elevation lichens. HYPOTHESES We aimed to test the following series of non-mutually exclusive hypotheses: 1. Dry thalli are less susceptible to freezing damage than are wet thalli. 2. Freeze-thaw cycles cause greater damage than continuous freezing. 3. Freeze-thaw cycles cause most damage to lichen from higher elevations. 4. Severe freezing temperatures have least impact on lichen from higher elevations. 5. Lichen from sites which rarely have sub-zero temperatures will be least able to recover after freezing damage.

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This is the supporting dataset to the paper Worthy et al. 2024 published in Scientific Reports. All methods used to produce the data are described in the methods section of the associated manuscript. A key is provided within each dataset to explain the headings and nature of each column of the data.

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