Ecotones as indicators: boundary properties in wetland-woodland transition zones

Abstract

Ecotones, representing the transition zones between species or communities, have been suggested as focal points for detecting early shifts in vegetation composition due to anthropogenic impact. Here we examined if changes in ecotone location or properties can be used as reliable indicators of hydrological change in temperate wetland communities. We examined 38 woodland-wetland-woodland transitions, distributed across four sites with different anthropogenic disturbance histories and hydrological traits. We tested whether: 1) the ecotones are associated with environmental gradients, and 2) the location or properties of these ecotones change with disturbance history. Well-defined ecotones were associated with steep gradients in soil depth and soil moisture. Most ecotones showed a change in vegetation from hydrophytic to dryland species. There was also some evidence that in highly disturbed sites the link between ecotones and environmental gradients was less apparent. By sampling across boundaries we can better understand the factors controlling the distribution of species. This allows us to make better predictions about the impacts of anthropogenic change in wetland communities. By investigating the transitions between different vegetation communities we were able to highlight key indicators that could be used to monitor these ecologically sensitive and diverse wetland communities.

Toward catchment hydro‐biogeochemical theories

“…More generally, developing integrated theories at the intersections of disciplines will require cultivating earth and environmental scientists who think across disciplinary boundaries with a broader hollistic perspective. Similar to ecotones in ecology, where the blending of distinct conditions brings about high biodiversity (Brownstein, Johns, Fletcher, Pritchard, & Erskine, 2015;Nadis, 2016), scientific ecotones can stimulate and pollinate innovative ideas across disciplines, therefore shedding new light on old questions and puzzles that individual disciplines cannot resolve. One such example is the flourishing field of ecohydrology since the call for understanding climate-soil-vegetation dynamics (Ingram, 1987;Rodriguez-Iturbe, 2000).…”

Deurbanized cities as strongly sustainable human settlements

“…These border zones could manifest in multiple ways: in holistic community parks, rewilded corridors in the periphery of the city, or the aforementioned food forests. Border zones are inspired by literature on ecotones, in this case also considering human beings as part of a zone's biodiversity (Brownstein et al, 2015).…”

Patterns of regional site index across a North American boreal forest gradient

“…In boreal forests, structural patterns reveal differences that can help identify important environmental gradients in soil moisture, nutrient availability, permafrost active layer depth, species composition, growth and carbon accumulation (Bonan and Shugart 1989). Site-scale (decameter) spatial shifts in these patterns through time may be induced by changes to the drivers of these gradients, and may signal ongoing or upcoming functional shifts in vegetation across broader landscapes (Epstein et al 2004, Wiegand et al 2006, Danz et al 2013, Brownstein et al 2015.…”