Root traits explain different foraging strategies between resprouting life histories

Abstract

Drought and fire are prevalent disturbances in Mediterranean ecosystems. Plant species able to regrow after severe disturbances (i.e. resprouter life history) have higher allocation to roots and higher water potential during the dry season than coexisting non-resprouting species. However, seedlings of non-resprouters have higher survival rate after summer drought. We predict that, to counteract their shallow-rooting systems and to maximize seedling survival, non-resprouters have root traits that confer higher efficiency in soil resource acquisition than resprouters. We tested this prediction in seedlings of less than 1.5 months old. We select 13 coexisting woody species (including both resprouters and non-resprouters), grew them in common garden and measured the following root traits: length, surface, average diameter, root tissue density (RTD), specific root length (SRL), surface:volume ratio (SVR), specific tip density (STD), tip distribution in depth, internal links ratio (ILR) and degree of branching. These root traits were compared between the two resprouting life histories using both standard cross-species and phylogenetic-informed analysis. Non-resprouters showed higher SRL and longer, thinner and more branched laterals, especially in the upper soil layers. The abundance, total length, diameter and SVR of external links (i.e. the most absorptive root region) were also higher for non-resprouters. The results were supported by the phylogenetic-informed analysis for the root traits most strongly related to soil resource acquisition (SRL, SVR and branching pattern). The seedling root structure of non-resprouters species allows them to explore more efficiently the upper soil layer, whereas seedling roots of resprouters will permit both carbon storage and deep soil penetration.

Trade-Offs between Drought Survival and Rooting Strategy of Two South American Mediterranean Tree Species: Implications for Dryland Forests Restoration

“…Clear differences in shoot and root growth confirm the different ecological requirements of each species (Q. saponaria and C. alba), and therefore their distinct capacities to resist drought conditions according to their rooting habits [18,20]. Recent studies suggest that there are major differences in the size and structure of the xylem networks and in physiological behavior among species with distinct root depths, resulting in different capacities to resist embolism and cavitation [14,33].…”

“…The success of deep-rooted Mediterranean forest species to survive dry conditions is in part due to their ability to develop a greater volume of thick roots responsible for colonizing moister soil strata [18,20]. Padilla et al [24] also suggests that a key role is higher specific root length to resist water stress.…”

Fine root biomass and dynamics in beech forests across a precipitation gradient – is optimal resource partitioning theory applicable to water‐limited mature trees?

“…Hence, changes in fine root morphological properties (such as specific fine root area or length) may also play an important role in the response of the trees' fine root system to differences in soil water availability. Producing fine roots of higher surface area and length and a larger number of root tips per unit carbon invested may therefore help to optimize the cost-benefit ratio of fine roots of a tree (Eissenstat & Yanai 1997;Eissenstat et al 2000;Ostonen et al 2007) and may increase the root water uptake capacity (Fitter 1986;Eissenstat 1991;Paula & Pausas 2011). Unfortunately, quantitative information on trends of root morphology along gradients of soil moisture has been rarely gathered so far.…”

Interactions between ecosystem properties and land use clarify spatial strategies to optimize trade-offs between agriculture and species conservation

“…SOC should increase with nutrient availability and ANPP (Bateman et al 2013;Conti & Díaz 2013;Doblas Miranda et al 2013). Increasing biomass removal should decrease ANPP (Lienin & Kleyer 2012), but may increase or conserve SOC due to compensatory growth of roots and rhizomes (Yu & Chmura 2009;Piñeiro et al 2010;Paula & Pausas 2011). Conversely, we expect a reduction in SOC where land-use intensification is accompanied by high levels of fertilization (Van Wesemael et al 2010).…”