Resource economics and coordination among above- and below-ground functional traits of three dominant shrubs from the Chilean coastal desert

Aims Plant functional traits determine how plants respond to environmen-tal factors and influence ecosystem processes.Among them,root traits and analyses of relations between above and below-ground traits in natural communities are scarce.Methods we characterized a set of above-and below-ground traits of three dominant shrub species in a semiarid shrub-steppe that had contrasting leaf pheno-logical habits(deciduous,semideciduous and evergreen).We ana-lysed if there was coordination among above-and below-ground resource economics patterns:i.e.patterns of biomass allocation,construction costs and lifespan.Important Findings Above-and below-ground traits and their resource economics relations pointed to species-specific functional strategies to cope with drought and poor soils and to a species ranking of fast to slow whole-plant strategies in terms of resource uptake,biomass con-struction costs and turnover.The deciduous shrub,Proustia cunei-folia,had relatively deep and even distribution of roots,and high proportion of short-lived tissues of low C construction costs:it had high fine to coarse root and high leaf-to-stem biomass ratios,high specific leaf area(SLA),and stems of low wood density.This strat-egy allows Proustia to maximize and coordinate above-and below-ground resources uptake as long as the most limiting factor(water)is available,but at the cost of having relative high plant biomass turnover.The evergreen Porlieria chilensis,instead,displayed a more conservative and slow strategy in terms of resource econom-ics.It had~80%of the roots in the 40 cm topsoil profile,low pro-portion of fine compared with coarse roots and low leaf-to-stem ratios,low SLA and stems of high wood density,i.e.it invested in C costly tissues that,overall,persist longer but probably at the cost of having lower plant resource uptake rates.Traits in the semide-ciduous Adesmia bedwellii were in between these two functional extremes.Our results revealed high functional diversity and above-and below-ground complementarity in resource economics among these three codominant species in the Chilean coastal desert.

Functional groups of Sahelian trees in a semiarid agroforestry system of Senegal

Aims Addressing plant responses to water stress is critical to understand the structure of plant communities in water-limited environments and to forecast their resilience to future changes in climate.In a semiarid agroforestry system in the Sahelian savannah of Leona(Senegal),we selected nine common tree species and explored their stress-resistance mechanisms.These species represent a variety of life forms and are of high regional socio-economic importance.We hypothesized that different species would show different suites of traits to cope with water stress and expected to identify functional groups differing in strategies to withstand water shortage.Methods Along a dry and a wet season,we monitored four traits reflecting above-and below-ground strategies of resource acquisition such as predawn leaf water potential(ψpd),specific leaf area(SLA),leaf thickness and leaf area index(LAI).We also measured two mor-phological traits:trunk diameter and tree height.LAI andψpd were measured six times during the dry and rainy seasons,and the other traits were measured once.Important Findings We identified two functional classes subdivided into two func-tional groups of each class.The first class included deciduous and semi-deciduous species that generally had large SLA,low leaf thickness and small-to-intermediate inter-seasonal varia-tions inψpd.The second class included evergreen species of two functional groups that differ in SLA,leaf thickness and the mag-nitude of inter-seasonal variations ofψpd throughout the year.The four functional groups identified in this study represent plant strategies differing in their response to changing environmental conditions.