Development of a novel framework for modeling field-scale conservation effects of depressional wetlands in agricultural landscapes

Agricultural Policy/Environmental eXtender (APEX) model visualization for three wetland restoration configurations: (a) the basic restored wetland configuration where a cultivated crop field drains directly into a restored wetland, (b) an enhanced wetland management scenario where a cultivated crop field drains through a grass filter strip and into a restored wetland, and (c) an enhanced wetland management scenario where a cultivated crop field was converted to a grassland and drains into a restored wetland. In all scenarios water flows from the wetland to the edge-of-field at the outlet point when the wetland is full of ponded water.

Mean annual edge-of-field losses from a 16 ha cultivated crop field or no-wetland scenario for a 30-year simulation. (a) Mean annual surface water runoff volume (Water, ha m), dissolved nitrogen mass (DN, kg), and dissolved phosphorus mass (DP, kg). (b) Mean annual total sediment mass (Total, Mg) losses, sediment-bound nitrogen (N, kg), and sediment-bound phosphorus (P, kg). Black error bars represent yearly variance as standard error.

Percentage annual reductions of surface water, dissolved nitrogen (DN) in runoff, and dissolved phosphorus (DP) in runoff loss of three restored wetland scenarios relative to the no-wetland scenario for a 30-year simulation. The dark blue bars represent mean percentage annual reductions when 0.92 of the field was restored as a functioning wetland. The medium blue bars represent mean percentage annual reductions when 0.92 ha of the field was restored as a functioning wetland and 0.15 ha of the field was converted to a grass filter strip surrounding the wetland. The light blue bars represent mean percentage annual reductions when the entire 2.19 ha cultivated cropland is replaced by grassland. Black error bars represent yearly variance as standard error.

Percentage annual reductions of field-to-wetland (a) surface water, dissolved nitrogen (DN), and dissolved phosphorus (DP) runoff and (b) sediment total, N, and P inputs from a 2.19 ha during a 30-year simulation. Bars represent mean percentage annual reduction in surface water and sediment-derived field-to-wetland inputs. The dark blue and red bars represent mean percentage annual field-to-wetland reductions when a 0.15 ha grass filter strip surrounds the simulated depressional wetland. The light blue and tan bars represent mean percentage annual field-to-wetland reductions when the whole 2.19 ha catchment is converted from a cultivated crop field to a grassland. Black error bars represent yearly variance as standard error.