scholarly journals Effects of harvesting and drought on CO2 and H2O fluxes in an aspen-dominated western boreal plain forest: early chronosequence recovery

2015 ◽  
Vol 45 (1) ◽  
pp. 87-100 ◽  
Author(s):  
R.M. Petrone ◽  
L. Chasmer ◽  
C. Hopkinson ◽  
U. Silins ◽  
S.M. Landhäusser ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Populus Tremuloides ◽  
Early Spring ◽  
Moisture Regime ◽  
Drought Period ◽  
Air Temperatures ◽  
Use Efficiency ◽  
Stand Height

This study examines the hydrological recovery of two regenerating boreal trembling aspen (Populus tremuloides Michx.) dominated stands and the sensitivity of that regeneration to drought within the first 5 years of establishment. The results indicate that evapotranspiration fluxes and water-use efficiency rebounded quickly as a result of new vegetation foliage growth and wet conditions found within the first 2 years following the harvest. However, a period of dry years had a significant influence on rates of postharvest growth, carbon dioxide (CO2), and water fluxes at these sites. The northern study area (NSA) and southern study area (SSA) were harvested in the winters of 2007 and 2008, respectively. The first and second years of regeneration at the SSA and NSA, respectively, were marked by an early spring thaw and higher-than-normal precipitation, while air temperatures remained slightly above the 30-year normal. During this period, mean measured height of vegetation tripled at both sites, and cumulative evapotranspiration was approximately 60% of that prior to harvest by the end of the second year of growth. By the third year (2009), the NSA became a sink for atmospheric CO2 during the snow free season (days of the year 128–238) despite low precipitation during the latter half of the summer. Volumetric soil moisture content in 2009 was the highest (on average) of the 5 years examined due to heavy snowfall and a late start to the growing season (where air temperatures consistently exceeded 0 °C), resulting in sustained productivity. However, cumulative annual precipitation also declined to 79% and 57% in 2009 and 2010, respectively, of the 30-year normal for that region, leading to significant (lagged) declines in forest productivity at the NSA in 2010 and 2011. This resulted in the site becoming a source of CO2 to the atmosphere during the 2010 and 2011 growing seasons (annual balance was not measured). Throughout the drought period (2009, 2010, and 2011), mean stand height increased by only 15%, 11%, and 14%, respectively, compared with the mean stand height in 2008. Water-use efficiency also declined in 2010 and 2011, whereas differences in light-use efficiency did not vary significantly because foliage was maintained (i.e., leaves did not abscise as a result of drought). The results of this study indicate that regenerating aspen stands are sensitive to drought and respond relatively quickly to changes in the soil moisture regime. This is important because regional drying as a result of predicted climatic changes combined with increased industrial activity may result in significant decline in productivity within these stands over broad regions.

EFFETS DE LA FUMURE POTASSIQUE ET DES RÉGIMES HYDRIQUES SUR LA RÉPONSE AU POTASSIUM DE LA LUZERNE ET DE LA FLÉOLE DES PRÉS

1987 ◽  
Vol 67 (4) ◽  
pp. 811-823
Author(s):  
J. L. DIONNE ◽  
A. R. PESANT ◽  
G. M. BARNETT
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Sandy Loam ◽  
Potassium Uptake ◽  
Moisture Regime ◽  
Exchangeable Potassium ◽  
Moisture Regimes ◽  
Use Efficiency ◽  
Dry Soil

The objectives of this study were to determine the changes in yield response and water use efficiency of alfalfa (Medicago sativa L. 'Saranac') and timothy (Phleum pratense L. 'Climax') to potassium applications and variations in soil moisture regimes. For each of the two test crops the factorial combination of the following treatments were replicated three times: three soils (Ste Rosalie clay, Greensboro loam, and Danby sandy loam), potassium (0, 25, 50 and 100 mg K kg−1 of dry soil) and three moisture levels: (1) optimal, 70–100% of available water (AW); (2) semi-dry, 0–100% AW; and (3) dry, 0–50% AW. Yield increases of 68% for alfalfa and 40% for timothy were produced by potassium applied to soil under the optimal moisture regime with almost no yield increase under dry soil moisture conditions. Water use efficiency was higher for alfalfa than for timothy, and increased with rates of potassium on Greensboro loam and Danby sandy loam but not on Ste Rosalie clay. Potassium content of alfalfa was lower when grown at optimal soil moisture than in the dry regime. Differences in potassium content between moisture regimes were small for timothy. Due to higher yields, potassium uptake by alfalfa was greater when soils were cropped at optimal moisture. However, less exchangeable potassium was found after the experiment in soils cropped to alfalfa in the optimal moisture regime than in soils under the dry moisture regime. Therefore potassium fertilizer was most effective at the optimal moisture level (near field capacity). Key words: Potassium fertilization, exchangeable potassium, soil moisture regime, potassium uptake, alfalfa, timothy

Water demand and water use efficiency of winter barley in Hungary

2011 ◽  
Vol 59 (1) ◽  
pp. 13-22
Author(s):  
Z. Varga-Haszonits ◽  
E. Enzsölné Gerencsér ◽  
Z. Lantos ◽  
Z. Varga
Keyword(s):  
Soil Moisture ◽  
Water Supply ◽  
Water Use Efficiency ◽  
Water Use ◽  
Potential Evapotranspiration ◽  
Growth Period ◽  
Winter Barley ◽  
Potential Yield ◽  
Yield Data ◽  
Use Efficiency

The temporal and spatial variability of soil moisture, evapotranspiration and water use were investigated for winter barley. Evaluations were carried out on a database containing meteorological and yield data from 15 stations. The spatial distribution of soil moisture, evapotranspiration and water use efficiency (WUE) was evaluated from 1951 to 2000 and the moisture conditions during the growth period of winter barley were investigated. The water supply was found to be favourable, since the average values of soil moisture remained above the lower limit of favourable water content throughout the growth period, except for September–December and May–June. The actual evapotranspiration tended to be close to the potential evapotranspiration, so the water supplies were favourable throughout the vegetation period. The calculated values of WUE showed an increasing trend from 1960 to 1990, but the lower level of agricultural inputs caused a decline after 1990. The average values of WUE varied between 0.87 and 1.09 g/kg in different counties, with higher values in the northern part of the Great Hungarian Plain. The potential yield of winter barley can be calculated from the maximum value of WUE. Except in the cooler northern and western parts of the country, the potential yield of winter barley, based on the water supply, could exceed 10 t/ha.

Studies of the Drip Method of Irrigation

1972 ◽  
Vol 8 (2) ◽  
pp. 171-175 ◽  
Author(s):  
I. P. Abrol ◽  
S. P. Dixit
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Soil Strength ◽  
Surface Evaporation ◽  
Evaporation Losses ◽  
Use Efficiency ◽  
Reduced Surface

SUMMARYA comparison has been made of drip and conventional check basin methods of irrigation, using onions and ladies finger as test crops. Significant increases in yield and water use efficiency in drip irrigated over conventionally irrigated plots resulted from increased availability of soil moisture at low tensions and reduced surface evaporation losses. Reduced soil strength in drip irrigated plots was also a factor resulting in increased yield of onions.

Site-level soil moisture controls water-use efficiency improvement and climate response in sugar maple: a dual dendroisotopic study

2021 ◽  
pp. 1-12
Author(s):  
R. Dietrich ◽  
F.W. Bell ◽  
M. Anand
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Tree Ring ◽  
Sugar Maple ◽  
Photosynthetic Capacity ◽  
Environmental Drivers ◽  
Tree Level ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Given the large contribution of forests to terrestrial carbon storage, there is a need to resolve the environmental and physiological drivers of tree-level response to rising atmospheric CO2. This study examines how site-level soil moisture influences growth and intrinsic water-use efficiency in sugar maple (Acer saccharum Marsh.). We construct tree-ring, δ18O, and Δ13C chronologies for trees across a soil moisture gradient in Ontario, Canada, and employ a structural equation modelling approach to ascertain their climatic, ontogenetic, and environmental drivers. Our results support previous evidence for the presence of strong developmental effects in tree-ring isotopic chronologies — in the range of −4.7‰ for Δ13C and +0.8‰ for δ18O — across the tree life span. Additionally, we show that the physiological response of sugar maple to increasing atmospheric CO2 depends on site-level soil moisture variability, with trees only in relatively wet plots exhibiting temporal increases in intrinsic water-use efficiency. These results suggest that trees in wet and mesic plots have experienced temporal increases in stomatal conductance and photosynthetic capacity, whereas trees in dry plots have experienced decreases in photosynthetic capacity. This study is the first to examine sugar maple physiology using a dendroisotopic approach and broadens our understanding of carbon–water interactions in temperate forests.

scholarly journals Assessing the Response of Ecosystem Water Use Efficiency to Drought During and after Drought Events across Central Asia

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 581 ◽  
Author(s):  
Jie Zou ◽  
Jianli Ding ◽  
Martin Welp ◽  
Shuai Huang ◽  
Bohua Liu
Keyword(s):  
Water Use Efficiency ◽  
Central Asia ◽  
Water Use ◽  
Severe Drought ◽  
Vegetation Types ◽  
Drought Period ◽  
Legacy Effect ◽  
Ecosystem Water Use Efficiency ◽  
Use Efficiency ◽  
The Mean

The frequency and intensity of drought are expected to increase worldwide in the future. However, it is still unclear how ecosystems respond to drought. Ecosystem water use efficiency (WUE) is an essential ecological index used to measure the global carbon–water cycles, and is defined as the carbon absorbed per unit of water lost by the ecosystem. In this study, we applied gross primary productivity (GPP), evapotranspiration (ET), land surface temperature (LST), and normalized difference vegetation index (NDVI) data to calculate the WUE and drought index (temperature vegetation dryness index (TVDI)), all of which were retrieved from moderate resolution imaging spectroradiometer (MODIS) data. We compared the mean WUE across different vegetation types, drought classifications, and countries. The temporal and spatial changes in WUE and drought were analyzed. The correlation between drought and WUE was calculated and compared across different vegetation types, and the differences in WUE between drought and post-drought periods were compared. The results showed that (1) ecosystems with a low (high) productivity had a high (low) WUE, and the mean ecosystem WUE of Central Asia showed vast differences across various drought levels, countries, and vegetation types. (2) The WUE in Central Asia exhibited an increasing trend from 2000 to 2014, and Central Asia experienced both drought (from 2000 to 2010) and post-drought (from 2011 to 2014) periods. (3) The WUE showed a negative correlation with drought during the drought period, and an obvious drought legacy effect was found, in which severe drought affected the ecosystem WUE over the following two years, while a positive correlation between WUE and drought was found in the post-drought period. (4) A significant increase in ecosystem WUE was found after drought, which revealed that arid ecosystems exhibit high resilience to drought stress. Our results can provide a specific reference for understanding how ecosystems will respond to climate change.

Studies on Transpiration Suppressants on Spring Sorghum in North-Western India in Relation to Soil Moisture Regimes. I. Effect on Yield and Water Use Efficiency

1984 ◽  
Vol 20 (2) ◽  
pp. 151-159
Author(s):  
D. Boobathi Babu ◽  
S. P. Singh
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Irrigation Water ◽  
Field Experiments ◽  
Western India ◽  
Moisture Regimes ◽  
Use Efficiency ◽  
Effect On Yield ◽  
North Western

SUMMARYThe results of field experiments conducted in the spring seasons (February/March to June) of 1980 and 1981 indicate that grain yields of sorghum increased with increase in frequency of irrigation. Crops sprayed with atrazine or CCC yielded more than the unsprayed control; maximum yields were obtained by the application of atrazine at 200 g ha−1. Water use efficiency decreased with increase in irrigation but increased as a result of spraying crops with either chemical. Irrigation water can be saved by the spraying of atrazine or CCC onto spring-sown sorghum.

Sign in / Sign up

Export Citation Format

Share Document