scholarly journals Analysis of growing season carbon and water fluxes of a subalpine wetland in the Canadian Rocky Mountains: implications of shade on ecosystem water use efficiency

2021 ◽  
Author(s):  
Dylan Hrach ◽  
Richard Petrone ◽  
Adam Green ◽  
Myroslava Khomik
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Rocky Mountains ◽  
Temporal Variability ◽  
Complex Terrain ◽  
Gross Primary Production ◽  
Growing Season ◽  
Canadian Rocky Mountains ◽  
Entire Study ◽  
Use Efficiency

Mountain regions are an important regulator in the global water cycle through their disproportionate water contribution. Often referred to as the “Water Towers of the World”, mountains contribute 40 to 60% of the world’s annual surface flow. Shade is a common feature in mountains, where complex terrain cycles land surfaces in and out of shadows over daily and seasonal scales. This study investigated turbulent water and carbon dioxide fluxes over the snow-free period in a subalpine wetland in the Canadian Rocky Mountains, from June 7th to September 10th, 2018. Shading had a significant and substantial effect on water and carbon fluxes at our site. Each hourly increase of shade per day reduced evapotranspiration (ET) and gross primary production (GPP) by 0.42 mm and 0.77 gCm-2, equivalent to 17% and 15% per day, respectively, over the entire study period. However, during only peak growing season, when leaves were fully out and mature, shade caused by the local complex terrain, reduced ET and increased GPP, likely due to enhanced diffuse radiation. The overall result was increased water use efficiency at the site during periods of increased shading during the peak growing season. In addition to incoming solar radiation (Rg), temporal variability in ET was found to relate to temporal variability in soil temperature, moisture and vapour pressure deficit. Shade impacted the curvature and intercept of the nonlinear ET-Rg relationship at our site. In contrast, temporal variability in GPP at our site was dependent largely on Rg only. Our findings suggest that shaded subalpine wetlands can store large volumes of water for late season runoff and are productive through short growing seasons.

scholarly journals SPATIO-TEMPORAL VARIATIONS OF SOIL WATER USE IN THE GROWING SEASON IN NORTHEAST CHINA USING MODIS DATA

2018 ◽  
Vol XLII-3 ◽  
pp. 137-141
Author(s):  
s. Chang ◽  
F. Huang ◽  
B. Li ◽  
H. Qi ◽  
H. Zhai
Keyword(s):  
Water Use Efficiency ◽  
Soil Water ◽  
Water Use ◽  
Northeast China ◽  
Gross Primary Production ◽  
Growing Season ◽  
Temporal Variations ◽  
Important Indicator ◽  
Modis Data ◽  
Use Efficiency

Water use efficiency is known as an important indicator of carbon and water cycle and reflects the transformation capacity of vegetation water and nutrients into biomass. In this study, we presented a new indicator of water use efficiency, soil water use level (SWUL), derived from satellite remote sensing based gross primary production and the Visible and Shortwave Infrared Drought Index (VSDI). SWUL based on MODIS data was calculated for the growing season of 2014 in Northeast China, and the spatial pattern and the variation trend were analyzed. Results showed that the highest SWUL was observed in forestland with the value of 36.65. In cropland and grassland, the average SWUL were 26.18 and 29.29, respectively. SWUL showed an increased trend in the first half period of the growing season and peaked around the 200th day. After the 220th day, SWUL presented a decreasing trend. Compared to the soil water use efficiency (SWUE), SWUL might depict the water use status at finer spatial resolution. The new indicator SWUL can help promote understanding the water use efficiency for regions of higher spatial heterogeneity.

Estimating the water use efficiency of spring barley using crop models

2018 ◽  
Vol 156 (5) ◽  
pp. 628-644 ◽  
Author(s):  
E. Pohanková ◽  
P. Hlavinka ◽  
M. Orság ◽  
J. Takáč ◽  
K. C. Kersebaum ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Spring Barley ◽  
Growing Season ◽  
Above Ground Biomass ◽  
Grain Yields ◽  
Crop Models ◽  
Average Value ◽  
Ground Biomass ◽  
Use Efficiency

AbstractIn the current study, simulations by five crop models (WOFOST, CERES-Barley, HERMES, DAISY and AQUACROP) were compared for 7–12 growing seasons of spring barley (Hordeum vulgare) at three sites in the Czech Republic. The aims were to compare how various process-based crop models with different calculation approaches simulate different values of transpiration (Ta) and evapotranspiration (ET) based on the same input data and compare the outputs of these simulations with reference data. From the outputs of each model, the water use efficiency (WUE) from Ta (WUETa) and from actual ET (WUEETa) was calculated for grain yields and above-ground biomass yield. The results of the first part of the study show that the model with the Penman approach for calculating ET simulates lower actual ET (ETa) sums, at an average of 250 mm during the growing season, than other models, which use the Penman–Monteith approach and simulate 330 mm on average during the growing season. In the second part of the current study, WUE reference values in the range 1.9–2.4 kg/m3were calculated for spring barley and grain yield. Values of WUETa/WUEETacalculated from the outputs of individual models for grain yields and above-ground biomass yields ranged from 2.0/1.0 to 5.9/3.8 kg/m3with an average value of 3.2/2.0 kg/m3and from 3.9/2.1 to 10.5/6.8 kg/m3with an average value of 6.5/4.0 kg/m3, respectively. The results confirm that the average values of all models are nearest to actual values.

scholarly journals Evapotranspiration, crop coefficient and water use efficiency of coriander grown in tropical environment

2018 ◽  
Vol 36 (4) ◽  
pp. 446-452 ◽  
Author(s):  
Vicente de PR da Silva ◽  
Inajá Francisco de Sousa ◽  
Alexandra L Tavares ◽  
Thieres George F da Silva ◽  
Bernardo B da Silva ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Crop Production ◽  
Field Experiments ◽  
Growth Parameters ◽  
Crop Coefficient ◽  
Growing Season ◽  
Tropical Environment ◽  
Mean Values ◽  
Use Efficiency

ABSTRACT The water scarcity is expected to intensify in the future and irrigation becomes an essential component of crop production, especially in arid and semiarid regions, where the available water resources are limited. Four field experiments were carried out at tropical environment in Brazil in 2013 and 2014, in order to evaluate the effect of planting date on crop evapotranspiration (ETc), crop coefficient (Kc), growth parameters and water use efficiency (WUE) of coriander (Coriandrum sativum) plants. The planting dates occurred during winter, spring, summer and autumn growing seasons. ETc was obtained through the soil water balance method and the reference evapotranspiration (ETo) through the Penman-Monteith method, using data collected from an automatic weather station located close to the experimental area. The results of the research showed that the mean values of coriander ETc and Kc were 139.8 mm and 0.87, respectively. Coriander water demand is higher in the summer growing season and lower in the winter; however, its yield is higher in the autumn and lower in the winter. Coriander has higher yield and development of its growth variables in the autumn growing season. The results also indicated that the interannual climate variations had significant effects on most growth variables, as yield, ETc and Kc of coriander grown in tropical environment.

Influence of row spacing on water use and yield of rain-fed wheat (Triticum aestivum L.) in a no-till system with stubble retention

2010 ◽  
Vol 61 (11) ◽  
pp. 892 ◽  
Author(s):  
S. G. L. Kleemann ◽  
G. S. Gill
Keyword(s):  
Grain Yield ◽  
Water Use Efficiency ◽  
Water Use ◽  
Vegetative Growth ◽  
Growing Season ◽  
Light Interception ◽  
Row Spacing ◽  
Spike Density ◽  
Stubble Retention ◽  
Use Efficiency

A 3-year field study was undertaken to investigate the effect of row spacing on vegetative growth, grain yield and water-use efficiency of wheat. All 3 years of the study experienced 21–51% below-average rainfall for the growing season. Widening row spacing led to reduced biomass and tillers on per plant basis which could be related to the reduction in light interception by the wheat canopy in the wide rows which in turn could have reduced assimilate production. Reduction in vegetative growth in 54-cm rows translated into a significant reduction in grain yield which was strongly associated (r2 = 0.71) with the loss of spike density. The pattern of crop water use (evapotranspiration, ET) during the growing season was very similar for the three row-spacing treatments. However, there was some evidence for slightly lower ET (~5%) in 54-cm rows in two growing seasons. More importantly, there was no evidence for increased ET during the post-anthesis phase in wide rows as has been speculated by some researchers. Over the 3 years of the study, grain yield declined by 5–8% as row spacing increased from 18 to 36 cm and by a further 12–20% as row spacing increased from 36 to 54 cm. There was a consistent decline in water-use efficiency for grain (WUEG) with increasing row spacing over the 3 years. WUEG declined by 6–11% as crop spacing increased from 18 to 36 cm and declined further by 12–15% as row spacing increased to 54 cm. Lower light interception at wider row spacing could have reduced assimilate production by wheat as well as increased soil evaporation due to lower shading of the soil surface in more open canopies. Growers adopting wider row spacing on these relatively heavy textured soils are likely to experience some reduction in grain yield and WUEG. However, some growers may be prepared to accept a small yield penalty from intermediate row spacing as a trade-off for increased stubble retention and soil health.

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