Ecosystem multifunctionality of coastal marshes is determined by key plant traits

Abstract

Questions As biodiversity losses increase due to global change and human‐induced habitat destruction, the relationships between plant traits and ecosystem properties can provide a new level of understanding ecosystem complexity. Using a functional response–effect approach, we show that multiple components of the carbon cycle are determined by a few plant traits, which in turn are strongly affected by environmental conditions. Location Salt marshes, northwest Germany. Methods We explored responses of morphological, chemical and biomass‐related plant traits to environmental drivers and examined their effects on carbon cycle properties, i.e. above‐ground biomass, above‐ground net primary productivity and decomposition. The combined analysis between environmental parameters, functional traits and ecosystem properties used structural equation modelling (SEM). Results Important response and effect traits were leaf dry matter content (LDMC) and below‐ground dry mass (BDM, responding to groundwater level and salinity) and leaf C:N ratio (responding to inundation frequency). Inundation and salinity led to increased allocation to below‐ground biomass and salt stress adaptation in leaves, which translated into increased decomposition rates. Release from these abiotic controls resulted in standing biomass accumulation, which was controlled by LDMC and canopy height as key traits. Conclusions These findings demonstrate the interacting effects of non‐consumable environmental factors and soil resources on morphological, chemical and biomass traits, which affected carbon cycle properties. Loss of species from the community has the potential to change the relationships between environment and vegetation‐based ecosystem properties and therefore elicit effects on the multifunctionality of the entire and adjacent ecosystems.

The influence of balanced and imbalanced resource supply on biodiversity–functioning relationship across ecosystems

“…The only field study showing a negative response of biomass production to increasing species richness was a study on plants in salt marshes (TREIBSEL, electronic supplementary material), where salinity and water regime, rather than nutrients, were the main drivers of diversity and biomass [36][37][38][39]. The limited ability of our model to explain variation in richness and realized productivity in salt marshes (only 8% for richness and 4% for realized productivity) seems to confirm that we did not quantify the key factors influencing this system.…”

Consistent drivers of plant biodiversity across managed ecosystems

“…Species composition and abundance were assessed by frequency analysis using a 1Â 1 m frame subdivided into 100 grids of 0.1Â 0.1 m. Nomenclature followed [34][35][36][37]. Further details of the study design for each project (except Comtess) can be found in [38] (Sequester), [22] (Treibsel) and [35,39] (Vista).…”

Sediment and carbon deposition vary among vegetation assemblages in a coastal salt marsh

“…Such a mechanism was supported by the constancy of molecular C composition between Juncus biomass and litter ( Table 2). The selective resorption of N by a plant has important implications for the fate and processing of the resulting litter and residue, as tissue C : N is considered a primary determinant on salt marsh OM decomposition (Minden and Kleyer, 2015). By retaining nutrients within the living tissues, the plant effectively decreases the lability of resulting litter and residual soils and makes them less attractive to the microbial decomposer community (Hessen et al, 2013;Sterner and Hessen, 1994).…”

“…Together, these data from SE Australia contribute to a broader pattern of plant assemblage differences in salt marsh surface dynamics and C sequestration potential (Minden and Kleyer, 2015;Saintilan et al, 2013;Wang et al, 2003). They also highlight short-term processes that may contribute to the high capacity of Juncus salt marshes to accumulate significant C stocks globally (0.034 g C cm −2 yr −1 or 0.093 mg C cm −2 d −1 ), relative to most other salt marsh genera (mean C accumulation rate = 0.024 g C cm −2 yr −1 or 0.066 mg C cm −2 d −1 ; Ouyang and Lee, 2014).…”