Ecohydrologic feedbacks controlling sizes of cypress wetlands in a patterned karst landscape

Abstract

Many landforms on Earth are profoundly influenced by biota. In particular, biota play a significant role in creating karst biogeomorphology, through biogenic CO2 accelerating calcite weathering. In this study, we explore the ecohydrologic feedback mechanisms that have created isolated depressional wetlands on exposed limestone bedrock in South Florida – Big Cypress National Preserve –as a case study for karst biogeomorphic processes giving rise to regularly patterned landscapes. Specifically, we are interested in: (1) whether cypress depressions on the landscape have reached (or will reach) equilibrium size; (2) if so, what feedback mechanisms stabilize the size of depressions; and (3) what distal interactions among depressions give rise to the even distribution of depressions in the landscape. We hypothesize three feedback mechanisms controlling the evolution of depressions and build a numerical model to evaluate the relative importance of each mechanism. We show that a soil cover feedback (i.e. a smaller fraction of CO2 reaches the bedrock surface for weathering as soil cover thickens) is the major feedback stabilizing depressions, followed by a biomass feedback (i.e. inhibited biomass growth with deepening standing water and extended inundation period as depressions expand in volume). Strong local positive feedback between the volume of depressions and rate of volume expansion and distal negative feedback between depressions competing for water likely lead to the regular patterning at the landscape scale. The individual depressions, however, are not yet in steady state but would be in ~0.2–0.4 million years. This represents the first study to demonstrate the decoupling of landscape‐scale self‐organization and the self‐organization of its constituent agents. © 2018 John Wiley & Sons, Ltd.

Tidal pumping and biogeochemical processes: Dissolution within the tidal capillary fringe of eogenetic coastal carbonates

“…TIDAL PUMPING AND BIOGEOCHEMICAL PROCESSES karstic surface topography in low-relief carbonate landscapes (Cohen et al, 2011;Chamberlin et al, 2018;Dong et al, 2018). Our results would therefore add to other published work that has extended biogeomorphic weathering processes into the subsurface (e.g.…”

Scale‐Dependent Patterning of Wetland Depressions in a Low‐Relief Karst Landscape

“…As such, our results imply that negative feedbacks on basin expansion act most on large basins, but more weakly on smaller basins. We interpret this as tentative evidence that the slow pattern genesis process is not yet at landscape equilibrium, a claim supported by recent landscape modeling (Dong et al, ).…”

Biogeomorphology, quo vadis? On processes, time, and space in biogeomorphology

“…(2020) use available mechanistic models (Delft3D and Landlab); Dong et al . (2019) and Román‐Sánchez et al . (2019a) use analytical models to solve a diffusion–advection equation and calculate the diffusivity constant and erosion–deposition rates; while Stavi et al .…”

“…In biogeomorphology, datasets of biologic and physical forms and processes are being combined. As a comparatively young sub‐discipline of geomorphology, there is still a need to develop models to simply conceptualize the interactions between biology and geomorphology over variable spatio‐temporal scales (Stavi et al ., 2018; Dong et al ., 2019; Gurnell et al ., 2019; Larsen et al ., 2019; Corenblit et al ., 2020). In the same sense, observations between biological and physical data at smaller scale are often used in simple rule‐based models that allow extrapolation of the general magnitude of effects to large scales (Mason et al ., 2019; Rice et al ., 2019).…”

“…(2020), and exploratory models, like Dong et al . (2019). Simulation models aim to reproduce the natural system as accurately as possible.…”