Alleviation of Summer Drought Boosts Establishment Success of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> in a Mediterranean Mountain: An Experimental Approach |
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Authors: | Email author" target="_blank">Jorge?CastroEmail author Regino?Zamora José A?Hódar José M?Gómez |
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Institution: | (1) Grupo de Ecología Terrestre. Departamento de Biología Animal y Ecología, Facultad de Ciencias, Universidad de Granada, Granada, E-18071, Spain |
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Abstract: | We performed an irrigation experiment to study the impact of summer drought on Pinus sylvestris establishment at its southernmost distribution limit. Watering was done during the first growing season simulating mesic
summer conditions, and we monitored the consequences for survival and growth during the first growing season and the delayed
consequences on the second growing season. In addition, we considered the heterogeneity created by the microhabitats, where
seeds are found after dispersal (bare soil, under shrubs, and under adult pines). Summer drought was the main mortality factor
in all the microhabitats. Watering increased emergence and doubled seedling survival compared to non-watered control sites.
Differences were even higher when the cumulative effect on emergence and survival was considered, with an overall recruitment
of 22.4% in watered plots vs. 7.9% in control. Irrigation increased growth in bare soil and under shrubs, but had scant effect
on growth under pines, suggesting that radiation was the limiting factor in this microhabitat. The positive effect of irrigation
on growth parameters persisted during the second growing season despite water was not added the second year, showing delayed
consequences of drought on seedling performance. Summer drought thus limits Pinus sylvestris establishment in these southernmost
forests by reducing both recruitment and growth. This might lead to the development of a remnant dynamic in these relict populations
under the current regional increase in dryness and rainfall variability associated with global warming. |
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Keywords: | Growth-survival conflicts Irrigation experiments Mediterranean ecosystems Pinus sylvestris |
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