Latitude dictates plant diversity effects on instream decomposition

Abstract

Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113° of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes.

Litter Quality Is a Stronger Driver than Temperature of Early Microbial Decomposition in Oligotrophic Streams: a Microcosm Study

“…As previously stated, forest changes can affect litter composition and decomposition rates, altering C flows [19], and this is not only a projection of climate change effects [13][14][15], but also natural forests suffering different sources of alternation [16][17][18]. Furthermore, these changes tend to reduce litter diversity, with repercussions for instream litter decomposition at the global scale [51]. The present study suggests that such replacements will have stronger effects for stream ecosystem functioning than temperature changes, in oligotrophic conditions.…”

Glacier shrinkage will accelerate downstream decomposition of organic matter and alters microbiome structure and function

“…Therefore, assessing controls on OM decomposition is critical to understand carbon fluxes through ecosystems and climate‐change impacts on this ecosystem process. Current understanding of OM decomposition in streams (Boyero et al, 2021; Rosemond et al, 2015; Tiegs et al, 2019) is rooted in early stream ecosystem science and biased toward the decomposition of terrestrial OM subsidies and its relevance for the “brown food web” (Webster & Benfield, 1986; Webster & Meyer, 1997). In this context, leaf litter bags and cotton strips that have been widely used as model substrates for OM degradation in running waters revealed latitudinal and altitudinal controls on OM decomposition rates (Boyero et al, 2021; Follstad Shah et al, 2017; Tiegs et al, 2019).…”

Pathways for cross-boundary effects of biodiversity on ecosystem functioning

“…Therefore, an increase in the richness of aquatic insect species with distinct life histories leads to variation in emergence periods, which implies enhanced prey supply to terrestrial predators that promotes productivity of the terrestrial consumer community. Moreover, given stoichiometric differences among species, in terms of C:N:P ratios or contents of vitamins or fatty acids, prey diversity would support greater biomass production of terrestrial consumers even when the total prey biomass is unchanged ('balanced diet hypothesis') [30]. Spawning salmon are a well…”