Shifting leaf fall phenology disrupts ecosystem function

Abstract

Leaf litter fall and processing in temperate streams is one of the most pervasive resource subsidies and ecosystem functions globally. 1 1. Tiegs, S.D. ∙ Costello, D.M. ∙ Isken, M.W. ... Global patterns and drivers of ecosystem functioning in rivers and riparian zones Sci. Adv. 2019; 5 , eaav0486 Crossref Scopus (187) PubMed Google Scholar , 2 2. Wallace, J.B. ∙ Eggert, S.L. ∙ Meyer, J.L. ... Stream invertebrate productivity linked to forest subsidies: 37 stream-years of reference and experimental data Ecology. 2015; 96 :1213-1228 Crossref Scopus (123) PubMed Google Scholar , 3 3. Wallace, J.B. ∙ Eggert, S.L. ∙ Meyer, J.L. ... Multiple trophic levels of a forest stream linked to terrestrial litter inputs Science. 1997; 277 :102-104 Crossref Scopus (1191) Google Scholar These subsidies are highly seasonally structured, yet their phenologies are shifting with climate change due to alterations of leaf senescence with global warming. 4 4. Delpierre, N. ∙ Dufrêne, E. ∙ Soudani, K. ... Modelling interannual and spatial variability of leaf senescence for three deciduous tree species in France Agric. Forest Meteorol. 2009; 149 :938-948 Crossref Scopus (276) Google Scholar , 5 5. Walther, G.-R. ∙ Post, E. ∙ Convey, P. ... Ecological responses to recent climate change Nature. 2002; 416 :389-395 Crossref Scopus (8303) PubMed Google Scholar , 6 6. Zhang, Y. ∙ Hong, S. ∙ Liu, Q. ... Autumn canopy senescence has slowed down with global warming since the 1980s in the Northern Hemisphere Commun. Earth Environ. 2023; 4 , 173 Crossref Scopus (22) Google Scholar As phenology and phenological changes are species specific, 7 7. Vitasse, Y. ∙ Porté, A.J. ∙ Kremer, A. ... Responses of canopy duration to temperature changes in four temperate tree species: Relative contributions of spring and autumn leaf phenology Oecologia. 2009; 161 :187-198 Crossref Scopus (277) PubMed Google Scholar the order of senescence of different leaf species is shifting. 8 8. Panchen, Z.A. ∙ Primack, R.B. ∙ Gallinat, A.S. ... Substantial variation in leaf senescence times among 1360 temperate woody plant species: implications for phenology and ecosystem processes Ann. Bot. 2015; 116 :865-873 Crossref Scopus (89) PubMed Google Scholar While the effect of phenology on community assembly and species interactions is well known, its influence on ecosystem function (particularly through the resource subsidy order of arrival and the duration between arrivals of different subsidies) remains underexplored. 9 9. Gallinat, A.S. ∙ Primack, R.B. ∙ Wagner, D.L. Autumn, the neglected season in climate change research Trends Ecol. Evol. 2015; 30 :169-176 Full Text Full Text (PDF) Scopus (461) PubMed Google Scholar Here, we tested how the order of arrival and exposition duration of resource subsidies affect ecosystem function. We conducted a mesocosm experiment manipulating the order of arrival of two contrasting leaf species (high- and low-nutrient content), testing the effects of subsidy order and duration on decomposition rates by an abundant aquatic shredder. Exposure duration and arrival order of leaf species strongly influenced combined leaf litter consumption. Earlier arrival of high-quality leaves enhanced feeding on low-quality leaves. Shifting leaf fall duration and order of arrival thus has the potential to impact carbon cycling, even when the combined resource quantity remains constant. Our study demonstrates that these changes can have direct consequences on ecosystem processes in the context of the globally important function of leaf litter processing, emphasizing the need for incorporating temporal ecological aspects to understand the climate change impacts on the functioning of ecosystems. 10 10. Hernández-Carrasco, D. ∙ Tylianakis, J.M. ∙ Lytle, D.A. ... Ecological and evolutionary consequences of changing seasonality Science. 2025; 388 , eads4880 Crossref Scopus (13) PubMed Google Scholar