Using geomorphological variables to predict the spatial distribution of plant species in agricultural drainage networks

Abstract

To optimize ecosystem services provided by agricultural drainage networks (ditches) in headwater catchments, we need to manage the spatial distribution of plant species living in these networks. Geomorphological variables have been shown to be important predictors of plant distribution in other ecosystems because they control the water regime, the sediment deposition rates and the sun exposure in the ditches. Whether such variables may be used to predict plant distribution in agricultural drainage networks is unknown. We collected presence and absence data for 10 herbaceous plant species in a subset of a network of drainage ditches (35 km long) within a Mediterranean agricultural catchment. We simulated their spatial distribution with GLM and Maxent model using geomorphological variables and distance to natural lands and roads. Models were validated using k-fold cross-validation. We then compared the mean Area Under the Curve (AUC) values obtained for each model and other metrics issued from the confusion matrices between observed and predicted variables. Based on the results of all metrics, the models were efficient at predicting the distribution of seven species out of ten, confirming the relevance of geomorphological variables and distance to natural lands and roads to explain the occurrence of plant species in this Mediterranean catchment. In particular, the importance of the landscape geomorphological variables, ie the importance of the geomorphological features encompassing a broad environment around the ditch, has been highlighted. This suggests that agro-ecological measures for managing ecosystem services provided by ditch plants should focus on the control of the hydrological and sedimentological connectivity at the catchment scale. For example, the density of the ditch network could be modified or the spatial distribution of vegetative filter strips used for sediment trapping could be optimized. In addition, the vegetative filter strips could constitute new seed bank sources for species that are affected by the distance to natural lands and roads.

The Use of Photogrammetry to Construct Time Series of Vegetation Permeability to Water and Seed Transport in Agricultural Waterways

“…An exhaustive characterization of channel species in April 2015 revealed an important diversity of plants with a richness similar to that observed in other channels located in the same geomorphological context [46]. The channel vegetation was mainly composed of Asteraceae and Poaceae species, with the latter being primarily located on the banks of the channel.…”

Generation of realistic synthetic catchments to explore fine continental surface processes

“…Our test‐case generation method exploits this function by adjusting the land use of a catchment according to its geomorphology. Moreover, numerous studies show close correspondences between landscape forms and land use in various regions of the world (Mesquita, 2008; Elhag & Boteva, 2017; Segundo et al, 2017; Rudi et al, 2018). We propose three land use scenarios showing different locations of forest cover depending on whether it is at the valley bottom, on the slopes, or on the plateaus: (i) in the first scenario, forest cover is concentrated at the bottom of the valley, and the surface is bare for the rest of the catchment area; (ii) in the second scenario, forest cover is located on the slopes, with a total absence of vegetation on the remaining surfaces; and (iii) the last scenario corresponds to the case where forest cover is located on the plateaus without any vegetation at the bottom of the valley or on the slopes.…”

Multifunctionality of agricultural channel vegetation : A review based on community functional parameters and properties to support ecosystem function modeling

“…Agricultural channel vegetation is generally composed of terrestrial and semiaquatic species (Bouldin et al, 2004;Clarke, 2015;Maheu-Giroux and Blois, 2006;Rudi et al, 2018b;Szymura et al, 2009), and sometimes of strictly aquatic species (Cassan et al, 2015;Clarke, 2015;Janse, 1998;Milsom et al, 2004;Sabbatini et al, 1998) Figure 1: Conceptual representation of the link between plant traits, plant community functional parameters and plant community properties, and ecosystem functions not), and other conditions (topographic, climatic, and pedological). They form sparse or dense cover that is homogeneously distributed in the channel or forms patches, as illustrated in Figure 2.…”

“…Channels and ditches generally have a high plant diversity (Meier et al, 2017). Plants living in agricultural channels are generally terrestrial or semiaquatic, composed mainly of forbs and graminoids (Bouldin et al, 2004;Clarke, 2015;Levavasseur et al, 2014a;Maheu-Giroux and Blois, 2006;Rudi et al, 2018b;Szymura et al, 2009), and sometimes strictly aquatic (Clarke, 2015;Janse, 1998;Milsom et al, 2004), according to the topographic, climatic, and pedological contexts, as well as location in the channels' network.…”