Pulses of seed release in riparian Salicaceae coincide with high atmospheric temperature

Abstract

Riparian shrubs and trees in the Salicaceae family release their seeds when floods that create nursery sites for germination are more frequent, but little is known about the factors controlling temporal variations in seed release within the seed release period.The seed release of three riparian tree species dominating European floodplain forests (Populus alba L., Populus nigra L., and Salix alba L.) was monitored in spring 2007 and 2008 using seed traps placed along the Middle Ebro River, NE Spain. Correlations relating biweekly seed rain intensity (seeds trapped per square meter) to meteorological (atmospheric temperature, cumulative precipitation, relative humidity, solar radiation, mean wind speed) and hydrological (river discharge) variables were investigated. The best combination of environmental variables explaining seed rain intensity was identified using an Akaike information selection criterion-based backward selection, after accounting for temporal autocorrelation both in seed rain intensity and environmental variables. Seed rain correlated positively with temperature for P. alba, P. nigra, and S. alba, though its effect decreased with relative humidity for P. nigra. Our results can help fine-tune the design of environmental flows to promote sexual recruitment of Salicaceae trees: Planning water releases during the hottest days of the seed dispersal period, when seed rain peaks, should maximize seed germination density and thus increase the potential for successful seedling establishment.

Growth Response of Cuttings to Drought and Intermittent Flooding for Three Salix Species and Implications for Riverbank Soil Bioengineering

“…discolor cuttings could also be an interesting alternative strategy to provide higher resilience to changing environmental conditions (such as climate-induced increases in summer drought; Garssen et al 2014;Bourgeois and González 2019) or optimized ecosystem functions (such as biodiversity support; Fang et al, 2015), and hence promote the success of bioengineering projects. While S. interior might appear less suitable for soil bioengineering given its lower relative investment in belowground biomass, it may be of interest for vegetating the lower parts of the banks.…”

“…These pioneer plants are characterized by morphological and dispersal strategies adapted to fluvial environments (Naiman et al 2005). One female willow can produce thousands to millions of seeds annually to be dispersed by wind and water, which confers these species a high colonization ability in the open, bare and moist riverbank surfaces that flooding disturbance leaves behind (Karrenberg et al 2002;González et al 2016;Bourgeois and González 2019). Once established, their dense and relatively deep root system further reduces uprooting risk during flooding and fosters soil stabilization (Karrenberg et al 2002;Catford and Jansson 2014).…”

Effects of ants on riparian poplars: an ex situ experiment of biotic interaction

“…Poplars have been widely studied to understand their responses to mechanical and physiological stress (González et al 2012;Singer et al 2013;Viger et al 2016;Ludovisi et al 2017), their biophysical effects on the environment (Gurnell et al 2012;Corenblit et al 2014;Gurnell 2014;Wintenberger et al 2015;Corenblit et al 2016a;Diehl et al 2017), as well as their population genetics and reproductive ecology (Chenault et al 2011;González et al 2016;Bourgeois and González 2019;Mazal et al 2021). Several studies also focussed on the positive (e.g.…”