Richard M. Petrone

Vineyards are highly heterogeneous systems where climate, soil, and management parameters can influence water loss by evapotranspiration (ET) across many spatial and temporal scales. To address vineyard variability of ET a multi‐method approach combining the use of in‐field atmometer ET gauges and the FAO‐56 dual crop coefficient procedure was employed. Spatial variability was addressed at two research sites in the Niagara (Ontario, Canada) growing region, Beamsville and Jordan, across three different cultivars: Chardonnay, Riesling, and Pinot Noir. It was hypothesised that variability in climatic controls including air temperature, precipitation, solar radiation, and wind dynamics would influence the variability in crop ET for each cultivar at both vineyards. Atmometer reference ET (ET ₀ ) and water stress adjusted crop ET (ETcadj) were consistent for white cultivars across each study site. Pinot Noir grapevines, however, exhibited lower daily atmometer ET ₀ , likely due to increased canopy shading or reduced wind turbulence to the canopy. The coefficient K _cb , which accounts for transpiration, was consistent for all cultivars at both sites, while K _e , the evaporation coefficient, showed a relationship between the soil water balance controlling water loss, especially regarding the Pinot Noir block. Water stress, represented by K _s , was present at harvest for both Riesling blocks, and Beamsville Chardonnay and Pinot Noir, and was associated with optimal Brix concentrations, derived from the harvested grapes specific to each block. Overall, both vineyards showed importance between soil moisture and energy supplies with ET _{c adj} , suggesting that changes in water and energy availability over the growing season are climatically significant to water loss and stress within each of the vineyard blocks. The use of atmometers in‐field, with adjustments by the FAO‐56 dual crop coefficient approach, is a simple and cost‐effective method that would allow growers to understand differences in vineyard‐scale meteorology and water loss by ET across multiple spatial and temporal scales within their vineyards.

Rapid mid-winter and early spring warming events are emerging as a key but under-recognized driver of carbon loss from cold-region ecosystems. In mountain peatlands, their influence remains largely unknown. Here, we quantify the impact of chinook wind events—warm, dry downslope winds that can raise air temperatures by over 20 °C within hours—on ecosystem respiration in a montane peatland on the eastern slopes of the Canadian Rockies. Using eddy covariance carbon dioxide (CO₂) flux measurements and meteorological data, 13 chinook events were identified between February and May 2021 and segmented each into pre-, during-, and post-event phases. A generalized additive mixed model accounting for temporal autocorrelation showed that CO₂ emission rates increased significantly during chinook events and remained elevated afterward. CO₂ emissions during snow-covered events in February-April were most likely driven by physical degassing from melting snow and thawing surface peat, whereas snow-free events in April and May likely reflected enhanced microbial activity in thawing peat. Our findings demonstrate that regularly occurring cold-season warming events can trigger substantial but short-lived CO₂ releases from mountain peatlands, revealing a climate-sensitive carbon loss pathway likely to intensify as snowpack duration shortens and freeze-thaw regimes shift in mountain regions world-wide.

The Canadian Rocky Mountains are a critical component to the hydrology, feeding water to many rivers. However, little is still known about the magnitude of hydrological processes (i.e., evapotranspiration (ET), discharge etc.) that comprise the alpine and subalpine hydrologic cycle. Sub‐alpine wetlands have received recent attention for their potential role as water retainers and sources for downstream systems. This purpose of this study was to quantify the ecohydrological controls on ET in a sub‐alpine wetland, using closed chamber measurements. Spatial patterns in evapotranspiration were modelled using the METRIC approach with data collected via a remote aerial vehicle (RAV). Closed chamber measurements for ET were taken in August, 2021, and the results indicated that vapour pressure deficit and net radiation were the significant controls on ET, while no significant influence was seen in vegetation type. The influence of the headwall was also clear as there were significant differences in ET between sunny (avg rate 0.14 ± 0.1 mm/h) and shady (avg rate 0.06 ± 0.4 mm/h) conditions. METRIC ET demonstrated considerable spatial variability, with higher rates located in the western portion of the field site, highlighting the complexity of quantifying ET in subalpine wetlands. When validated against the closed chamber data, METRIC ET captured the general range of ET measurements reasonably well, and had a modelled root mean square error (RMSE) of 0.07 mm/h. However, we recommend that future research test METRIC performance under different seasonal conditions to better quantify the model's capabilities.

Vineyards are highly heterogeneous systems where climate, soil, and management parameters are capable of influencing water loss by evapotranspiration (ET) across many spatial and temporal scales. To address vineyard variability of ET a multi-method approach combining the use of in-field atmometer ET gauges and the FAO-56 dual crop coefficient procedure were employed. Spatial variability was addressed at two research sites in the Niagara (Ontario, Canada) growing region, Beamsville and Jordan, across three different cultivars: Chardonnay, Riesling and Pinot Noir. It was hypothesized that variability in climatic controls including air temperature, precipitation, solar radiation, and wind dynamics, would influence the variability in crop ET for each cultivar at both vineyards. Reference ET (ET _o ) and water stress adjusted crop ET (ET _{c adj} ) were consistent for white cultivars across each study site. Pinot Noir grapevines, however, saw lower daily ET _o , likely due to increased canopy shading, or reduced wind turbulence to the canopy. The coefficient K _cb , which accounts for transpiration, was consistent for all cultivars at both sites, while K _e , the evaporation coefficient, showed a relationship between the soil water balance controlling water loss, especially regarding the Pinot Noir block. Water stress, represented by K _s , was present at harvest for both Riesling blocks, and Beamsville Chardonnay, and was associated with optimal Brix values. Overall, Beamsville blocks were associated closely with net solar radiation, relative humidity and vapor pressure deficits, suggesting sensitivity to atmospheric controls. Jordan grapevine ET _{c adj} was controlled by volumetric water content, air temperature and water-use-efficiency, indicating relationships between ET _{c adj} and water stress. The use of atmometers in-field, with adjustments by the FAO-56 dual crop coefficient approach, is a simple and cost-effect method that would allow growers to understand differences in climate-based terroir components and water loss by ET across multiple spatial and temporal scales within their vineyards.

In recognition of the need for sustainable land use practices, environmental regulations require landscapes affected by resource extraction in the Athabasca Oilsands Region to be reclaimed to their pre‐disturbance functionality. Thus, pilot‐scale watersheds have been constructed to examine the viability of reclamation endeavours in the region. As water availability is a primary driver of ecosystem function, an understanding of water usage and movement during the different phases of ecosystem development is required to ensure successful reclamation. This study captured the evolving evapotranspiration (ET) regime during the initial 7 years post‐construction of a fen‐upland watershed. Both landscapes exhibited significant biophysical evolution, from bare ground to fully vegetated ecosystems. During bare ground conditions, ET was driven by atmospheric and edaphic controls. In the fen, ponded conditions resulted in consistently high rates of surface evaporation throughout the growing season (3.8 mm/day). In contrast to the drier upland, which exhibited limited evaporation rates (1.2 mm/day), punctuated by small increases in response to precipitation events. Once a plant community was well established, edaphic controls decreased, and ET fluxes were largely driven by plant‐mediated responses to atmospheric conditions. In the fen, widespread plant coverage and the establishment of a thick litter layer suppressed surface evaporative losses but increased transpiration, ultimately resulting in lower ET rates (2.5 mm/day). In the upland, the growth and development of treed species resulted in a marked increase in ET rates (2.6 mm/day). These rates are comparable to those of natural landscapes in the region, suggesting successful establishment of ecohydrological function.

Climate change presents unique challenges for grape growers across the world. In Ontario, three distinct viticultural regions are experiencing climatic shifts towards warmer growing seasons. According to historical records collected from Environment and Climate Change Canada, Lake Erie North Shore has transitioned from an intermediate-to-warm growing season classification, the Niagara Peninsula from the lower to upper limits of the intermediate zone, and Prince Edward County from cool to intermediate, when analyzing their average growing season temperatures. Terroir is directly related to vine water status, an indicator of grapevine stress. Biophysical responses controlled by air temperature and precipitation include fluctuations in vapour pressure deficits, evapotranspiration, and water-use-efficiency rates, as well as soil water content levels. By conducting an extensive literature review, the development of a conceptual model addresses how variations in climatic controls, under the scope of climate change, may influence grapevine water status, biophysical responses, and associated production outcomes for Ontario vineyards. Cool-to-intermediate air temperatures, when paired with increased precipitation will lead to no or low vine stress, increasing photosynthesis and transpiration rates, and variable plant water-use-efficiency levels, producing higher yields and lower quality grapes, if no management strategies are applied. Oppositely, higher air temperature as a product of climate change, when paired with variable precipitation may produce mild-to-severe stress, reducing yield, and increasing grape quality. With the appropriate management strategies, both traditional and new, growers may be able to accommodate for the influence of climate change on their vineyards.

Open‐canopy forested systems are found across a range of terrestrial biomes. Forest structure and organization in open‐canopy systems exhibit substantial controls on system process dynamics such as evapotranspiration (ET). The energy reaching sub‐canopy forest layers is greater in open‐canopy systems compared to closed canopy systems, with high spatiotemporal variability in the distribution of energy that both drives ET and controls sub canopy species composition and organization. Yet the impact of their structural complexity and organization on whole system ET dynamics is poorly understood. Using the BETA+ model and measured eddy covariance‐based ET fluxes from a boreal treed peatland, we critically evaluate how stand compositional and organizational complexity influences ET dynamics. Model simulations iteratively increase complexity from a simple ‘big‐leaf’ model to a model representing spatial complexity of all system layers, demonstrating the effect of each complex system component on stand ET dynamics. We show that including forest stand complexity and associated canopy and radiation variability increases ET model estimates by ~26%. In addition to changes in the ET estimates, the inclusion of this spatial complexity is shown to induce temporal variations in the simulated ET that improves model performance by reducing unexplained variance between modelled and measured ET by 10% and reducing hysteresis in model results. These results have clear implications for flux modelling of forest systems and for larger scale climate models where open canopy systems such as this dominate the landscape. Demonstrating that whilst big leaf simulation can approximate ET fluxes, the inclusion of forest‐stand complexity and its influence on spatiotemporal radiation fluxes and ecohydrological processes are necessary to effectively represent ET dynamics within open canopies.