Differences in the environmental control of leaf senescence of four Quercus species coexisting in a Mediterranean environment

Abstract

Aims of study: Our aim is to check the effect of different environmental factors on the leaf senescence of four Quercus species with different leaf longevities, to help us better understand the implications of climate change on leaf demography.Area of study: The study was carried out in two sites of the province of Salamanca (central-western Spain), both sites showing differences in their temperatures and soil water availability.Material and Methods: Over four years (2007)(2008)(2009)(2010) we monitored the number of leaves of the different cohorts labelled on five specimens of each species at both sites to elaborate life-tables and calculate mortality rates. Mortality rates were then related to several other variables measured during the same period: air temperature, soil water availability, precipitation, predawn water potentials (Ψ pd ) and leaf N resorption.Main results: In the two deciduous species maximum daily temperatures and the time during which their values remain above a certain threshold (between 11 and 12ºC of maximum daily temperature) are the main factors controlling the timing of leaf abscission. In the evergreen species abscission of old leaves showed no relationship with the environmental factors analyzed. By contrast, mortality rates of old leaves were related to seasonal N resorption values, with the maximum mortality of old leaves coinciding in time with the maximum withdrawal of N from shed leaves and also with the emergence of the new leaf cohort.Research highlights: The increase in the duration of the leaves of the two deciduous species, as a result of the delayed senescence by warmer autumnal temperatures, could contribute to reducing the differences in the length of the productive leaf life with respect to the evergreen species. This could improve the competitive capacity of deciduous species as opposed to that of evergreen species, and thus alter their respective distribution patterns.

Regeneration dynamics in fragmented landscapes at the leading edge of distribution: Quercus suber woodlands as a study case

“…As shown in these studies, winter and spring precipitation exerted a large positive effect on treering growth due to the replenishment of soil water reserves before the onset of the favorable growing season (Costa et al 2001;Jovellar et al 2010;Costa et al 2016;Zribi et al 2016;Leite et al 2019). In our study site, Q. suber showed the latest leaf emergence of all coexisting Quercus species, with budbreak and emergence of the new leaf cohort occurring between the end of May and the beginning of June (del Río et al 2015). However, in relation to other studies where temperature has been found to have an insignificant or negative effect over cork or ring growth (Caritat et al 1996;Costa et al 2001;Zribi et al 2016), in our study site, the mean and minimum temperatures during winter and/or spring and the mean and maximum temperatures during September exerted a positive influence on tree growth.…”

Regeneration Dynamics in Fragmented Landscapes at the Leading Edge of Distribution: Quercus Suber L. as A Study Case

“…S1), but it is also directly involved in improving soil water retention in abandoned cultivars, especially in soils with high sand content (Rawls ). In our study site, Q. suber showed the latest leaf emergence of all coexisting Quercus species, with budbreak and emergence of the new leaf cohort occurring between the end of May and the beginning of June (del Río et al 2015). However, in relation to other studies where temperature has been found to have an insigni cant or negative effect over cork or ring growth (Caritat et al 1996, Costa et al 2001, Zribi et al 2016, in our study site, the mean and minimum temperatures during winter and/or spring and the mean and maximum temperatures during September exerted a positive in uence on tree growth.…”

Climatic regulation of leaf and cambial phenology in Quercus pubescens: Their interlinkage and impact on xylem and phloem conduits

“…The positive effect of autumn temperature on leaf senescence was also confirmed in Mediterranean tree species. Del Río García et al (2015) reported delayed leaf senescence due to warmer autumn conditions in four coexisting Mediterranean Quercus species. This may lead to smaller differences in the length of productive leaf life of deciduous species compared to evergreen species, thereby improving the competitive ability of the former (del Río García et al, 2015).…”