The importance of landscape diversity for carbon fluxes at the landscape level: small‐scale heterogeneity matters

Abstract

Landscapes can be viewed as spatially heterogeneous areas encompassing terrestrial and aquatic domains. To date, most landscape carbon (C) fluxes have been estimated by accounting for terrestrial ecosystems, while aquatic ecosystems have been largely neglected. However, a robust assessment of C fluxes on the landscape scale requires the estimation of fluxes within and between both landscape components. Here, we compiled data from the literature on C fluxes across the air-water interface from various landscape components. We simulated C emissions and uptake for five different scenarios which represent a gradient of increasing spatial heterogeneity within a temperate young moraine landscape: (I) a homogeneous landscape with only cropland and large lakes; (II) separation of the terrestrial domain into cropland and forest; (III) further separation into cropland, forest, and grassland; (IV) additional division of the aquatic area into large lakes and peatlands; and (V) further separation of the aquatic area into large lakes, peatlands, running waters, and small water bodies These simulations suggest that C fluxes at the landscape scale might depend on spatial heterogeneity and landscape diversity, among other factors. When we consider spatial heterogeneity and diversity alone, small inland waters appear to play a pivotal and previously underestimated role in landscape greenhouse gas emissions that may be regarded as C hot spots. Approaches focusing on the landscape scale will also enable improved projections of ecosystems' responses to perturbations, e.g., due to global change and anthropogenic activities, and

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte‐dominated systems with zero net effect on carbon burial

“…Highly productive macrophyte-dominated freshwater systems (Kazanjian et al, 2018) play an important role in long-term carbon storage at the landscape (Premke et al, 2016) and even at the global scale (Mulholland & Elwood, 1982). Our experimental results suggest that 1 year of 4°C warming will increase production and sedimentation of organic carbon in these systems.…”

Integrating Aquatic and Terrestrial Perspectives to Improve Insights Into Organic Matter Cycling at the Landscape Scale

“…Landscapes are spatially heterogeneous entities encompassing terrestrial and aquatic domains tightly connected by flows of OM, energy, and organisms across ecosystem boundaries (Loreau et al, 2003;Premke et al, 2016). Analogous to the meta-population concept, this complex array of ecosystems has been expressed as a "meta-ecosystem" (Loreau et al, 2003), in which both biotic and abiotic factors vary among entities including OM transformation processes acting at a wide range of temporal and spatial scales, e.g., from rapid OM mineralization to long-term C stabilization at micro-to landscape scales.…”

“…Bidirectional processes can greatly alter OM transformation and turnover by frequent changes in environmental conditions which then set the framework for further OM processing (Premke et al, 2016). The transition from one environment to another during OM movement across ecosystem boundaries greatly determines the environmental settings for OM degradation; not only due to changes in the availability of OM and nutrients, but also due to abrupt changes or gradients in many environmental features controlling microbial and decomposer community composition and their related activities.…”

“…This process is predicted by adaptive management research (Holling, 2001) that anticipates a period of renewal in which resources or ideas are assembled in various often unsystematic ways to serve as the building blocks of something novel. This period of change is evident in the literature as OM retention and release has been addressed from different perspectives: at the ecosystem level (Schmidt et al, 2011), the terrestrial-aquatic connectivity concept (Marin-Spiotta et al, 2014), the priming frame work (Guenet et al, 2010;Bianchi, 2011), and the linkage of carbon cycling across various spatial and temporal scales (Premke et al, 2016). Thus, our goal is to present a novel framework of OM cycling that synthesizes many of these ideas, but primarily focuses on the flows of material and energy and their interactions across landscape properties and scales.…”

The Net Landscape Carbon Balance—Integrating terrestrial and aquatic carbon fluxes in a managed boreal forest landscape in Sweden

“…To determine the landscape-scale C budgets, previous studies have commonly applied upscaling approaches based on plot or ecosystem-level measurements (e.g., Aurela et al, 2015;Fu et al, 2014;Jonsson et al, 2007). However, such upscaling exercises propagate considerable uncertainty from the individual measurements and furthermore cannot account for effects from the connectivity and interactions between the terrestrial and aquatic compartments (Premke et al, 2016). Alternatively, tall-tower eddy covariance measurements provide a top-down approach that integrates all vertical fluxes to a direct measure of the net CO 2 and CH 4 exchanges between the entire landscape and the atmosphere (e.g., Barcza, Kern, Haszpra, & Kljun, 2009;Chi et al, 2019;Davis et al, 2003;Desai et al, 2015;Haszpra, Hidy, Taligás, & Barcza, 2017;Peltola et al, 2015).…”