Climate-driven changes of riparian plant functional types in permanent headwater streams. Implications for stream food webs

Abstract

Little is known regarding consequences of climate change on riparian plant functional types (PFTs) related to leaf traits, with putative domino effects on stream food webs, plausible even if the tipping point of stream-desiccation is not reached. We hypothesized that, as stream food-webs are highly dependent on riparian subsidies, climate change might alter PFTs to the point of weakening terrestrial-aquatic linkages. We conducted a gradient analysis to assess the relative effects of climate, soil and riparian physical characteristics on PFTs. If PFTs differ significantly in leaf traits and climate had major influences on them, we could assume space-for-time interchangeability forward in time to predict leaf traits changes, and consequences for stream food webs under future climate change scenarios. Results indicated a clear distinction in leaf traits among PFTs: woody deciduous plants showed leaf traits associated to high decomposability and nutritional value for invertebrate shredders compared to evergreen woody and giant graminoid groups. We found a prime role of climate predicting changes in abundance and diversity of PFTs: 1) a warming and precipitation-decline scenario, coupled with soil characteristics related to aridification, would have detrimental effects on deciduous plants, while fostering giant graminoids; 2) in a scenario of no precipitation-reduction in wetter areas, warming might promote the expansion of evergreen to the detriment of deciduous plants. In both scenarios the net outcome implies increasing recalcitrance of leaf litter inputs, potentially weakening terrestrial-aquatic linkages in headwater streams.

Strategies of shredders when feeding on low‐quality leaf‐litter: Local population adaptations or fixed species traits?

“…Our data revealed lower average nutritive value of the riparian foliage in warmer or in warm/semiarid zones. These results, together with other recent observations (e.g., Salinas et al 2018), support the notion that climate change can likely exacerbate the large dietary imbalance of stream detritivores (Cross et al 2005), either due to plant species turnover (interspecific variability) or phenotypic plasticity of species (intraspecific variability). However, results from our experiments did not support our hypothesis: the responses of feeding and growth rates, and assimilation, to changes in litter quality did not differ between populations of the three shredder species, and when exceptions did occur, these were most likely not due to local adaptations to use low-quality litter (discussed below).…”

Warming and nutrient-depleted food: Two difficult challenges faced simultaneously by an aquatic shredder

“…Experimental studies have found that elevated [CO 2 ] increases the C ∶ N ratio of tree leaves and causes greater accumulation of secondary chemicals (Stiling and Cornelissen 2007), which might adversely influence riverine shredders (Tuchman et al 2002). Further, gradient studies at regional (Chen et al 2013, Salinas et al 2018 and global (Yuan andChen 2009, Boyero et al 2017) scales predict that warming could significantly reduce leaf N and P (or just P). Some of these studies also point to warming-derived changes in other leaf traits of riparian vegetation, such as increasing silicon content and toughness (Boyero et al 2017, Salinas et al 2018, which can interfere with the feeding and digestive E-mail addresses: 3 encarnafenoy@ual.es; 4 fjmoyano@ual.es; 5 jjcasas@ual.es DOI: 10.1086/709023.…”

“…Further, gradient studies at regional (Chen et al 2013, Salinas et al 2018 and global (Yuan andChen 2009, Boyero et al 2017) scales predict that warming could significantly reduce leaf N and P (or just P). Some of these studies also point to warming-derived changes in other leaf traits of riparian vegetation, such as increasing silicon content and toughness (Boyero et al 2017, Salinas et al 2018, which can interfere with the feeding and digestive E-mail addresses: 3 encarnafenoy@ual.es; 4 fjmoyano@ual.es; 5 jjcasas@ual.es DOI: 10.1086/709023. Received 15 June 2019; Accepted 26 November 2019; Published online 22 June 2020.…”

Impactos del cambio climático sobre la flora acuática de las Lagunas Verdes, volcán Chiles, Ecuador

“…Las fluctuaciones del nivel de agua de las lagunas, han dejado al descubierto, por tiempos prolongados, las zonas litorales de estos cuerpos de agua, afectando las condiciones naturales de los ciclos de vida de las plantas acuáticas (Villaroel et al, 2014). Esta transformación es aprovechada por las especies helófitas, las cuales toleran zonas de anegación, pero que en determinadas épocas del año pueden llegar a secarse por completo, ganando cada vez más el espacio de los litorales lacustres (Salinas et al, 2018).…”