## 2 Materials and Methods
### Data Collection  
#### 2.2.1 Vegetation  
At each site, two transects were established where plant heights, stomatal resistance, and leaf area index (LAI) were measured every 3-5 days, at \(\sim\)10 m intervals (Figure 1B,C). Alfalfa transects were approximately 50 m long with relief varying from 330.56-331.97 m asl. The maize site included transects on the north (127 m) and south (96 m long) sides of the Creek, spanning relief gradients 327.94-333.78 m asl and 327.90-331.49 m asl,respectively. Coordinates and relief were determined using a Differential Global Positioning System device (Viva GS14 GNSS RTK, Leica Geosystems, St. Gallen, Switzerland; \(\pm\)0.5 cm vertical accuracy). On each sampling date, three plants were selected randomly at each 10 m interval and heights were measured from ground to top of plant using a standard measuring tape. In addition, a single plant was randomly selected at each 10 m interval for stomatal resistance measurements using an open chamber leaf porometer (SC-1, Decagon Devices, Pullman, WA, USA), where three leaves in the upper canopy, middle canopy, and lower canopy were measured. The upper canopy was characterized by little to no shading from sun exposure, while the middle canopy represented the middle third of the stem and was characterized by some shading, and the lower canopy experienced significant amounts of shading. LAI measurements were conducted using a LI-COR 2200C (Li-Cor Inc., Lincoln, NE, USA) when sky conditions were clear or consistently overcast. LAI data was run through FV2000 software (Li-Cor Inc., Lincoln, NE, USA), which accounted for scattering correction. Dates in which the instrument reported unrealistic, or non-values, were discarded; 12 dates were included (2 discarded) from the alfalfa site and 11 dates (3 discarded) from the maize site. Samples of alfalfa and maize were harvested four times throughout the season to quantify biomass accumulation for periods within the growing season. A 50 \(\times\) 50 cm quadrat was placed at three randomly selected locations along transects. Within each quadrat, vegetation was harvested for above ground biomass (AGB). Samples were dried at 80 \({}^{\circ}\)C for 72 h before being weighed for dry biomass. At the maize site, 40 \(\times\) 50 cm sampling areas were used to better represent 80 cm crop row spacing. Alfalfa cumulative biomass was calculated using a linear regression equation (R\({}^{2}\) = 0.88) between height and biomass measurements collected at each harvest. The use of this linear regression was justi  
Figure 1: Location of (**A**) study sites and Hopewell Creek Watershed within Southern Ontario, and alfalfa (**B**) and maize (**C**) fields with location of transects, and eddy covariance/meteorological tower. (**A**) is adapted from Irvine (2018) and satellite imagery of (**B,C**) were extracted from Google Earth (2020) using imagery from 7 July 2018 and 9 August 2018, respectively. The dotted lines in relief gradients in (**B,C**) show discontinuation, where the transect ends and the other begins on the other side of the Creek. Panel A source: CanMap Water and OMNRF Watersheds Tertiary, DMTI Spatial Inc., Markham, ON, Canada. fied despite a low sample size since height measurements at harvest dates occurred prior to stem elongation ending and \"cut at first flower\" techniques were implemented. Some thickening occurs during stem elongation, which would be accounted for in height-biomass relationship, but lignification of phloem and xylem, which would be a significant source of deviation to measured height-biomass relationship, occurs after stem elongation has completed [35]. In the study of [36], measured canopy height was the most effective parameter at explaining variation in alfalfa biomass, which accounted for 68.5% of variation under a cut at 10% flower scenario.