Monitoring framework for paired experiments to assess the changes in the water balance in urban forests and grass-covered plots

Large-scale vegetation establishment has not only helped to prevent serious soil and water loss on the Loess Plateau of China but also led to reduced water availability and soil desiccation. Examining the water balance of forested and farmed land allowed us to determine water consumption of vegetation and understand the mechanisms of soil desiccation, important factors for the sustainable conversion of farmland to forest in this area. The effects of forests and crops on the water balance within the soil–vegetation–atmosphere system were studied using a coupled water and heat flow model known as “CoupModel”, which was calibrated on the basis of field measurements of soil water content, surface runoff, throughfall, stemflow, leaf area index, vegetation cover, canopy height and depth of root system in the hill and gully region of the Loess Plateau. Data were collected between 27 May 2006 and 31 October 2007. Two types of planted vegetation (acacia forest and farmland) in the Yan'gou watershed in the northern part of the Shaanxi Province were chosen to examine water transfer in the absence of soil texture (silt loam) differences and to explore the importance of vegetation type in relation to water balance. The simulations indicated that vegetation type and slope aspect significantly influenced the magnitude of every water balance component in the soil–vegetation–atmosphere system. Compared to forest, farming the land reduced interception (69.1–78.3%) and transpiration (37.3–40.4%), while increasing surface runoff by a factor of 5.0–40.2 and soil evaporation by 3.1–32.0%. Thus, farming resulted in 1.1–1.2 times more soil water storage than afforestation. Therefore, canopy interception and transpiration are responsible for soil desiccation in plantation forests. Simulation differences in water balance between acacia forest and farmland highlight that when converting farmland to forest on the Loess Plateau of China, tree species should be selected with care; this is particularly important on south-facing slopes.

The southern mountainous taiga of eastern Siberia has a sparse larch canopy and an understory dominated by a thick moss layer. The physiology of moss is very different from that of other plants, as mosses lack roots and vascular systems and take up water directly. During May 2002, we conducted hydrological and meteorological measurements in the taiga of eastern Siberia to investigate the role of understory moss on water and energy balances within a leafless larch forest. We found that below‐leafless canopy net all‐wave radiation partitions into 39% latent heat flux and 39% sensible heat flux, while the mean daily Bowen ratio is about 1. Ground heat flux on the moss surface is also an important factor, as it comprises 22% of net all‐wave radiation. Evaporation from moss beneath the leafless canopy was 24 mm during the 1‐month observation period, representing 23% of the water flux into the larch forest. This finding implies that moss intercepted 23% of the water flux into the larch forest. In addition, evaporation from the moss understory during May 2002 comprised 22% of total evapotranspiration previously estimated above the canopy (April–October 2001). We conclude that moss is an important component of the water and energy balance in larch forests in the taiga region. Copyright © 2007 John Wiley & Sons, Ltd.

Climate plays a pivotal role in construction of relationships between coniferous forest health and water balance for efficient biosynthesis under changing meteorological variables. Here we identify that the age of the forest (young 200 years old) confers an improved ecophysiology for the maintenance of water balance through the response of trees to weather conditions (precipitation, temperature and water balance in different seasons). Global climate change, of the rise in temperatures, has an impact on the environment of mountain ecosystems in the Alps. Subalpine forests enhance partitioning precipitation inputs, with interception processes in the tree canopy determining the stability of the proportion of water reaching the ground and its quantity in the form of evaporation. These processes support global improvements in forest ecosystems at the catchment scale, as interception is influenced by the structure and density of the tree canopy and the presence of epiphytes. This study revealed that coniferous forests (spruce, fir and pine) have a significant influence on how much water is retained and discharged in the soil and plants. Interception in dense subalpine forests can account for a significant proportion of precipitation. Data analysis using Python-based modeling revealed that forest age increases biosynthesis by enhancing water fluxes. This study highlights the significance of uncovering hidden climate-environment determinants leading to improved forest hydrology and ecophysiology to enhance the biosynthesis and water balance in coniferous forests of the Alps.

<p>Subalpine forests in the Alps are fragile ecosystems with high importance for human water resources and the local and mesoscale climate. While previous studies have measured different components of the water balance, little is known about the partition of all the water components during the same period and the role of forest age. We were able to measure the water balance components and will show how water distributed in the forest. Some highlights of our study are the evidences that canopies of old forests were able to intercept water in larger extend than the young forest canopies, representing the largest water reservoir, the frequency of fog during the study period, shown for the first-time in this ecosystem, the larger ratio of throughfall related to precipitation during days with mixed precipitation (fog and rainfall) and the role of epiphytes in the water balance.</p>

Water balance in coniferous forest dominated by Picea abies L. and Pinus cembra L. is a central process contributing to global carbon and water cycling. Quantifying the roles of the major biotic and abiotic agents that influence water balance, i.e., lichens and fog, is thus important for a better understanding of this process. Methods to quantify water balance, such as evapotranspiration, precipitation, and temperature suffer from several shortcomings, such as destructive sampling or subsampling. We developed and tested a Python-based statistical approach based on computed environmental and climate parameters obtained from Eddy covariance measurements of coniferous forests from a field experiment with dominated by Swiss pine and spruce as major tree species. W e quantified the volume of key meteorological parameters in forest canopies with old (> 200 y.o.) and young (< 30 y.o.) trees and relative water vapour volume showing signs of contribution from fog. The data were compared using Matplotlib library of Python for statistical analysis for both types of trees. Fog and lichens were identified with high accuracy and strongly correlated with water content in coniferous forests. Our data show that this is a powerful approach in silviculture for quantifying water balance using Python and statistical analysis of datasets. In contrast to other methods, Python programming libraries offer a flexible yet powerful toolset for data analysis. Additionally, non-destructive field measurements were performed across the entire study area, providing spatially explicit information on forest health. This integrated approach opens a wide range of research opportunities in nature conservation and land management within protected areas of mountainous coniferous forests.

물 부족으로 인해 수자원의 확보와 효율적인 관리의 중요성이 커지고 있음에도 불구하고, 물 수지 분석에서 증발산은 다른 성분에 비해 직접 관측이 어려워 물수지 방정식으로부터 어림되거나 단순한 가정이나 경험식으로부터 추정된다. 그러나 이러한 방법들은 오차가 커서 증발산의 신뢰도를 높이려면 직접 관측이 필요하다. 이 연구에서는 설마천 유역의 혼효림의 증발산을 정량화하기위해 2007년 9월부터 2008년 12월까지 에디 공분산 방법을 사용하여 증발산을 직접 측정하였다. 혼효림의 증발산은 성장기(5-7월)에는 평균 <TEX>$2.2mm\;d^{-1}$</TEX>, 비성장기인 겨울에는 <TEX>$0.5mm\;d^{-1}$</TEX>였다. 2008년 한 해동안의 총 증발산량은 <TEX>$581mm\;y^{-1}$</TEX>로 연 강수량(1997mm)의 약 1/3을 차지하였다. 2007년과 2008년에 관측이 겹치는 기간(9-12월)동안 적산된 증발산 총량은 2008년 가을의 강수량과 강수빈도가 2007년의 같은 기간에 비해 적었음에도 불구하고 두 기간 모두<TEX>${\sim}110mm$</TEX>로 다르지 않았다. 산림과 대기간의 분리(decoupling) 정도를 나타내는 오메가 인자는 평균 0.5로서 평형증발산과 부과증발산이 전체 증발산에 기여하는 정도가 크게 다르지 않았다. 이는 증발산이 순복사, 포차, 기공전도도 등에 의해 골고루 영향을 받고 있음을 의미한다. 본 연구에서는 실측에 근거한 증발산 자료를 토대로 설마천 유역의 혼효림에서 증발산이 물수지에서 차지하는 기여도를 조사하였고, 향후 유출량과 함께 사용될때 설마천 산림유역의 물수지 분석의 신뢰도을 향상시킬 것으로 기대된다. The importance of securing water resources and their efficient management has attracted more attention recently due to water deficit. In water budget analysis, however, evapotranspiration(<TEX>${\lambda}E$</TEX>) has been approximated as the residual in the water balance equation or estimated from empirical equations and assumptions. To minimize the uncertainties in these estimates, it is necessary to directly measure <TEX>${\lambda}E$</TEX>. In this study, using the eddy covariance technique, we have measured <TEX>${\lambda}E$</TEX> in a mixed forest in the Seolmacheon catchment in Korea from September 2007 to December 2008. During the growing season(May-July), <TEX>${\lambda}E$</TEX> in this mixed forest averaged about <TEX>$2.2\;mm\;d^{-1}$</TEX>, whereas it was on average <TEX>$0.5\;mm\;d^{-1}$</TEX> during the non-growing season in winter. The annual total <TEX>${\lambda}E$</TEX> in 2008 was <TEX>$581\;mm\;y^{-1}$</TEX>, which is about 1/3 of the annual precipitation of 1997 mm. Despite the differences in the amount and frequency of precipitation, the accumulated <TEX>${\lambda}E$</TEX> during the overlapping period(i.e., September to December) for 2007 and 2008 was both <TEX>${\sim}110$</TEX> mm, showing virtually no difference. The omega factor, which is a measure of decoupling between forest and the atmosphere, was on average 0.5, indicating that the contributions of equilibrium <TEX>${\lambda}E$</TEX> and imposed <TEX>${\lambda}E$</TEX> to the total <TEX>${\lambda}E$</TEX> were about the same. The results suggest that <TEX>${\lambda}E$</TEX> in this mixed forest was controlled by various factors such as net radiation, vapor pressure deficit, and canopy conductance. In this study, based on the direct measurements of <TEX>${\lambda}E$</TEX>, we have quantified the relative contribution of <TEX>${\lambda}E$</TEX> in the water balance of a mixed forest in the Seolmacheon catchment. In combination with runoff data, the information on <TEX>${\lambda}E$</TEX> would greatly enhance the reliability of water budget analysis in this catchment.

Water balance in a moist semi-deciduous forest in Ghana

Brief information about water balance of the Carpathian temperate forest ecosystem are presented in the paper. Experimental research was done in a mature mixed fir-spruce-beech stand in the research plot “Pol’ana-Hukavský gruň” (850 m a.s.l.) in the south-eastern part of Pol’ana Mts. in the Biosphere Reserve UNESCO in Central Slovakia. Individual parameters of water budget have been continuously monitored. The water consumption of the model beech trees, as well as approximate model beech stand transpiration was estimated on the basis of sap flow measurements and up-scaling through dendrometrical approach. Sap flow of model beech trees was estimated by direct, non-destructive and continuous measurements by tree-trunk heat balance method with internal heating and sensing of temperature. These values were compared with potential evapotranspiration according to Turc. Precipitation parameters (rain and snow precipitation, through-fall precipitation, stem-flow, fog/snow precipitation and infiltration) have been measured simultaneously. Results of mass water balance and the portion of the tree transpiration within the individual water flows are presented. Evapotranspiration of beech-fir forest ecosystem in the middle mountain region (850 m a.s.l.) includes: transpiration (35% of precipitation total), interception (21%), evaporation (8%). There are differences between tree species in mass of transpirated water. Transpiration of spruce and fir reaches two-thirds of beech transpiration. Fog precipitation contribution to the water balance of beech-fir stand is 5%. Concurrently fog precipitation lowers the interception losses of vertical precipitation.

"Evaporation of Snow Intercepted by a Todo-fir Forest (I) Water Balance Easurements." Journal of Forest Research, 2(1), p. 67

The allocation of groundwater resources has been a challenge for many years due to its unforeseen side effect and lag time issues, which are often overlooked. The full impact of groundwater utilization/abstraction takes time to realize its effect at its full. In this paper, long-term effects and groundwater dynamics were assessed using a water balance model and a time series analysis, respectively. Undeveloped groundwater systems are commonly found in a state of equilibrium, where, on average, equal amounts of water are recharged and discharged. A water budget is a static accounting of the state of the system at a given time, often before the system is developed. Water balance analysis was carried out together with the groundwater through flow, hydrograph, and surface-groundwater interaction analysis (base flow index) to develop a conceptual water balance model, which is a very basic representation of a complex natural aquifer system and is instrumental to constrain and build a robust numerical model that can be readily justified and updated. A noble approach was employed to assess and constrain the discharge coming out of the model area to sustain the lake level, located to the north of the study area, using the whole lake catchment and lake water balance analysis. Based on the lake water balance, there is a deficit between input and output computation, and hence there should be a groundwater input to sustain the historical lake area. The analysis showed that the model area contributes 40% of the lake catchment, and hence the portion of the groundwater inflow feeding the lake was computed. This is one of the means to constrain the discharge, which adds more confidence to the recharge estimation. This is very important because the size of a sustainable groundwater development usually depends on how much of the discharge from the system can be captured by the development. Capture is independent of the recharge. Instead, it depends on the dynamic response of the aquifer system to the development. The idea that knowing the recharge is important in determining the size of a sustainable groundwater development is a myth and has no basis. The important entity in determining how a groundwater system reaches a new equilibrium is capture. How capture occurs in an aquifer system is a dynamic process. Following this study, lake water balance assessment was indirectly considered as prior information for the numerical model calibration of the discharge from the model area using a conductance parameter. Conductance is a key parameter to estimate the discharge volume together with the change in the simulated hydraulic head between time steps. The water balance error highlights which one is more sensitive, and this could help to assist in planning for future data collection/field work and where to invest the money. The water balance computation helps to figure out the degree of surface-groundwater interaction, uncertainty, sensitive parameter, helps in the decision to invest time and money, and operates as a cross check with other analytical or numerical modelling.

采用调查分析方法,研究长沙城市森林土壤Zn、Cu、Ni、Pb、As、Cd、Hg7种重金属含量,并以长沙市土壤背景值和湖南省土壤背景值为参比值,采用Hakanson潜在生态危害指数法评价不同城市化梯度森林土壤重金属潜在生态风险。结果表明:7种重金属的平均含量均随着城市化程度提高而增加,Pb增幅最大,As增幅最小。同一城市化梯度森林土壤均以Zn平均含量最高,Cd最低,但均未超过土壤环境质量标准(GB15618-1995)Ⅱ级标准值。在城市中心区,桂花树林、樟树+桂花树混交林土壤Zn、Cu、Pb、As、Hg平均含量普遍较高,而樟树+马尾松混交林、桂花树+杜英混交林土壤Cu、Ni、As、Cd、Hg平均含量普遍较低,Pb、Zn空间分布差异明显,Cd、Ni、As空间分布比较均匀,Cu、Ni、Pb、As、Cd、Hg之间(除Cd与As、Ni之间外)均存在显著(<em>P</em>＜0.05)或极显著(<em>P</em>＜0.01)的相关性,与土壤有机质之间也呈显著(<em>P</em>＜0.05)或极显著(<em>P</em>＜0.01)的相关性,Zn、Cu、Ni、Pb、As、Cd、Hg主要是人为输入;中心区森林土壤重金属的潜在生态危害已达到中等生态危害程度,边缘区接近中等生态危害程度,郊区为轻微生态危害程度,Zn、Cu、Ni、Pb、As均为轻微生态危害程度,Cd、Hg已达到中等生态危害程度以上。;In order to understand the influence of urbanization on distribution of heavy metals in soils, concentrations characteristics of 7 heavy metals (Zn, Cu, Ni, Pb, As, Cd, and Hg) in various forest types were investigated along an urban gradient in Changsha, a capital city of Hunan Province, China. The concentrations and potential ecological risk of heavy metals in the urban soils was assessed when compared to the background values of heavy metals in soils in both Changsha city and Hunan Province. A total nineteen major forest types were selected at three locations (namely urban district location, urban fringe location, and suburban location) along the urban gradient degree in urban forests soil in the Changsha city. Two forest plots (each with the size of 20m × 20m) were built in each forest types. Three subplots were (each with an area of 1 m²) were set up in each of the plots. Five soil samples (from 0-20 cm depth) were randomly taken within each subplot and pooled to a soil sample for heavy metals chemical analysis, 0-20cm soil samples were collected from different urban gradient (urban district, urban fringe, suburban) forest to analyze the concentrations of Zn, Cu, Ni, Pb, As, Cd, and Hg, and the potential ecological hazard assessment indices by Hakanson was used to assess the soil heavy metals potential ecological risk degree in urban forest, based on the background values of soil in Changsha City and in Hunan Province. Results showed that the average concentration of the same heavy metal elements in urban forest soils tended to increase with degree of urbanization. Pb had the maximum increasing value and As the minimum. In the same urbanization location degree, Zn had the highest average concentration and Cd had the lowest one among the studied of all test heavy metals., On average, while the average the concentrations of all examined heavy metals them in study sites were lower than those in the Environmental Quality Standard for Soil (Ⅱgrade) in China.,. The heavy metals whose concentrations were higher than the background values in Changsha cite and the accumulation tendency of test heavy metals in urban forest were as in the order as of Cd＞Hg＞As＞Pb＞Cu (Ni)＞Zn in the study sites. The concentration of re existed some differences in the same heavy metal element varied concentration with among different types forest types in the city, The average concentrations of Zn, Cu, Pb, As, and Hg were as higher in <em>Osmanthus fragrans</em> forests and, <em>Cinnamomum camphora Presl.</em> and<em> Osmanthus fragrans </em>mixed forests, but that of Cu, Ni, As, Cd, and Hg were found to be was low concentrations in<em> Cinnamomum camphora Presl.+ Pinus massoniana </em>mixed forests and, <em>Osmanthus fragrans +Elaeocarpus sylvestris Poir </em>mixed forests, the spatial distribution patterns of Pb and Zn was significant different in the study area, while Cd, Ni and As were more evenly distributed. Significant correlations were found among Zn, Cu, Ni, Pb, As, Cd, and Hg concentrations in soils (<em>P</em>< 0.05), except the relationships between Cd and As, and Ni. The 7 heavy metals had positively significant correlations with soil organ matter. It was found that Zn, Cu, Ni, Pb, As, Cd and Hg mainly came form the anthropogenic inputs in the urban district forests. Based on potential ecological risk assessment, the situation of heavy metals was in the medium ecological risk level in urban district locations, was in closing to the medium level in urban fringe locations, and was in a slight level in suburban locations in Changsha cite. Among the studied heavy metals, Zn, Cu, Ni, Pb, and As were in a slight risk level, while Cd and Hg were in medium or strong ecological risk level. Our study provided scientific reference to estimate and evaluate the impact of urbanization on heavy metals in Southern China.

Assessing the impacts of irrigated agriculture on hydrological regimes in an oasis-desert system

Interannual variation of water balance and summer evapotranspiration in an eastern Siberian larch forest over a 7-year period (1998–2006)

In the Patagonia Andean Region, silvopastoral system success depends on forestry management, which seeks to guarantee highest water input into the soil to forage production. The aim of this study was to quantify and compare different components of the water balance in a Pinus radiata forest under two different management practices: silvopastoral and forest treatment (325 and 622 trees/ha, respectively). In order to explain incident precipitation distribution within the forest, different variables were measured: direct precipitation, stemflow, interception, soil moisture content, percolation and evapotranspiration. Additionally, canopy cover, leaf area index (LAI) and forage production was determined. Silvopastoral system, with respect to forest system, presented higher direct precipitation (84±1 vs. 75±2%), lower stemflow (2±0.3 vs. 3±0.27%), lower interception (14±1 vs. 22±2%), higher soil moisture content (24.2±2.5 vs. 20.9±2.1%) and lower canopy cover (70.9±0.05 vs. 74.89±0.34%). In turn, percolation (0.33±0.12 vs. 0.11±0.08%), evapotranspiration (78.2 vs. 73.3%), pasture production (230.76±97.57 vs. 66.60±60.02 kg MS.ha-1.year-1) and LAI (1.28±0.04 vs. 1.31±0.02) were similar in both systems. These results show that management density modified only some components of water balance. However, adding more water the silvopastoral system was not reflected in an increase in pasture production. Density management is key, mainly in silvopastoral system, where different system components must be raised up for a more efficient water usage. https://doi.org/10.25260/EA.19.29.2.0.776

Measurements of root zone soil water content and soil hydraulic properties at the flux tower sites were conducted during the course of the Boreal Ecosystem‐Atmosphere Study (BOREAS) experiment. Instrumentation included neutron probe, time domain reflectometry (TDR), and tension infiltrometer. Several methods of data visualization were employed to demonstrate fluctuations in soil water content with depth and time during the intensive field campaigns (IFCs). These methods started with two‐dimensional plots of soil water content as a function of time and depth and evolved into the construction of three‐dimensional soil water prisms. The prisms were constructed by using cubic‐spline (vertical z‐direction) and linear (horizontal x‐direction) interpolations for soil water content and linear interpolations along the time (y direction) axis. The prisms allow for animation along any plane or combination of planes to demonstrate the evolution of soil water conditions due to evapotranspiration, drainage, and precipitation. Soil hydraulic properties were determined at the flux tower sites based on analysis of in situ tension infiltrometer tests and soil water retention data from laboratory analysis of soil cores. Results from this analysis are saturated hydraulic conductivity and fitting parameters for the van Genuchten soil water retention function and Mualem hydraulic conductivity function at each flux tower site. These functions are required for physically based simulation models of soil water dynamics, soil water balance, and the interaction of the soil profile with the atmospheric boundary layer. Examples of cumulative evapotranspiration and drainage calculated from the soil water balance are presented and compared with flux tower measurements.