Effects of fine-scale soil moisture and canopy heterogeneity on energy and water fluxes in a northern temperate mixed forest

2014 ◽  
Vol 184 ◽  
pp. 243-256 ◽  
Author(s):  
Lingli He ◽  
Valeriy Y. Ivanov ◽  
Gil Bohrer ◽  
Kyle D. Maurer ◽  
Christoph S. Vogel ◽  
...  
2008 ◽  
Vol 148 (5) ◽  
pp. 723-737 ◽  
Author(s):  
Yuji Kominami ◽  
Mayuko Jomura ◽  
Masako Dannoura ◽  
Yoshiaki Goto ◽  
Koji Tamai ◽  
...  

2021 ◽  
Author(s):  
Sebastián Páez-Bimos ◽  
Veerle Vanacker ◽  
Marcos Villacis ◽  
Marlon Calispa ◽  
Oscar Morales ◽  
...  

<p>The high tropical Andes ecosystem, known as páramo, provides important hydrological services to densely populated areas in the Andean region. In order to manage these services sustainably, it is crucial to understand the biotic and abiotic processes that control both water quality and fluxes. Recent research in the páramo highlights a knowledge gap regarding the role played by soil-vegetation interactions in controlling soil-water processes and resulting water and solute fluxes.</p><p>Here, we determine the hydrological and geochemical fluxes in four soil profiles in the páramo of the Antisana´s water conservation area in northern Ecuador. Water fluxes were measured biweekly with field fluxmeters in the hydrological year Apr/2019- Mar/2020 under two contrasting vegetation types: tussock-like grass (TU) and cushion-forming plants (CU). Soil solution was collected in parallel with wick samplers and suction caps for assessing the concentrations of dissolved cations, anions and organic carbon (DOC). In addition, soil moisture was measured continuously in the upper meter of the soil profile, i.e. first three horizons (A, 2A and 2BC), using water content reflectometers. The vertical water flux in the upper meter of each soil profile was simulated using the 1D HYDRUS model. We carried out a Sobol analysis to identify sensitive soil hydraulic parameters. We then derived water fluxes by inverse modeling, based on the measured soil moisture. We validated the calculated water fluxes using the fluxmeter data. Solute fluxes were estimated by combining the water fluxes and the soil solution compositions.</p><p>Our preliminary results suggest that water fluxes and DOC concentration vary under different vegetation types. The fluxmeter data from the 2A horizon indicates that the cumulative water flux under TU (2.8 - 5.7 l) was larger than under CU (0.8 – 1.1 l) during the dry season (Aug-Sep and Dec-Jan). However, the opposite trend was observed in the wet season for maximum water fluxes. Moreover, the DOC concentration in the uppermost horizon was higher under CU (47.3 ±2.2 mg l<sup>-1</sup>) than under TU (3.1 ±0.2 mg l<sup>-1</sup>) vegetation during the monitoring period. We associate the water and solute responses under different vegetation types to the contrasting soil hydro-physical and chemical properties (e.g., saturated hydraulic conductivity and organic carbon content) in the uppermost soil horizon. Our study illustrates the existence of a spatial association between vegetation types, water fluxes and solute concentrations in Antisana´s water conservation area. By modelling the hydrological balance of the upper meter of the soil mantle, the water and solute fluxes will be estimated for soils with different vegetation cover.</p><p> </p>


2017 ◽  
Vol 31 (3) ◽  
pp. 339-349 ◽  
Author(s):  
Wu Haohao ◽  
Xu Xingkai ◽  
Duan Cuntao ◽  
Li TuanSheng ◽  
Cheng Weiguo

AbstractPacked soil-core incubation experiments were done to study the effects of carbon (glucose, 6.4 g C m−2) and nitrogen (NH4Cl and KNO3, 4.5 g N m−2) addition on nitrous oxide (N2O) and carbon dioxide (CO2) fluxes during thawing of frozen soils under two forest stands (broadleaf and Korean pine mixed forest and white birch forest) with two moisture levels (55 and 80% water-filled pore space). With increasing soil moisture, the magnitude and longevity of the flush N2O flux from forest soils was enhanced during the early period of thawing, which was accompanied by great NO3−-N consumption. Without N addition, the glucose-induced cumulative CO2fluxes ranged from 9.61 to 13.49 g CO2-C m−2, which was larger than the dose of carbon added as glucose. The single addition of glucose increased microbial biomass carbon but slightly affected soil dissolved organic carbon pool. Thus, the extra carbon released upon addition of glucose can result from the decomposition of soil native organic carbon. The glucose-induced N2O and CO2fluxes were both significantly correlated to the glucose-induced total N and dissolved organic carbon pools and influenced singly and interactively by soil moisture and KNO3addition. The interactive effects of glucose and nitrogen inputs on N2O and CO2fluxes from forest soils after frost depended on N sources, soil moisture, and vegetation types.


2009 ◽  
Vol 6 (8) ◽  
pp. 1423-1444 ◽  
Author(s):  
T. Keenan ◽  
R. García ◽  
A. D. Friend ◽  
S. Zaehle ◽  
C. Gracia ◽  
...  

Abstract. Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations. Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches. The effectiveness of two models, one a dynamic global vegetation model ("ORCHIDEE"), and the other a forest growth model particularly developed for Mediterranean simulations ("GOTILWA+"), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements. In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO2 and water fluxes. However, accurate predictions of both CO2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates.


2021 ◽  
Author(s):  
Mengyuan Mu ◽  
Martin De Kauwe ◽  
Anna Ukkola ◽  
Andy Pitman ◽  
Teresa Gimeno ◽  
...  

<p>Land surface models underpin coupled climate model projections of droughts and heatwaves. However, the lack of simultaneous observations of individual components of evapotranspiration, concurrent with root-zone soil moisture, has limited previous model evaluations. Here, we use a comprehensive set of observations from a water-limited site in southeastern Australia including both evapotranspiration and soil moisture to a depth of 4.5 m to evaluate the Community Atmosphere-Biosphere Land Exchange (CABLE) land surface model. We demonstrate that alternative process representations within CABLE had the capacity to improve simulated evapotranspiration, but not necessarily soil moisture dynamics - highlighting problems of model evaluations against water fluxes alone. Our best simulation was achieved by resolving a soil evaporation bias; a more realistic initialisation of the groundwater aquifer state; higher vertical soil resolution informed by observed soil properties; and further calibrating soil hydraulic conductivity. Despite these improvements, the role of the empirical soil moisture stress function in influencing the simulated water fluxes remained important: using a site calibrated function reduced the soil water stress on plants by 36 % during drought and 23 % at other times. These changes in CABLE not only improve the seasonal cycle of evapotranspiration, but also affect the latent and sensible heat fluxes during droughts and heatwaves. The range of parameterisations tested led to differences of ~150 W m<sup>-2</sup> in the simulated latent heat flux during a heatwave, implying a strong impact of parameterisations on the capacity for evaporative cooling and feedbacks to the boundary layer (when coupled). Overall, our results highlight the opportunity to advance the capability of land surface models to capture water cycle processes, particularly during meteorological extremes, when sufficient observations of both evapotranspiration fluxes and soil moisture profiles are available.</p>


2022 ◽  
Vol 269 ◽  
pp. 112847
Author(s):  
Ran Meng ◽  
Renjie Gao ◽  
Feng Zhao ◽  
Chengquan Huang ◽  
Rui Sun ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document