Comparing the space-time distribution of soil water storage for two forest ecosystems using spatio-temporal kriging (original) (raw)
Related papers
Soil water dynamics and long-term water balances of a Douglas fir stand in the Netherlands
Journal of Hydrology, 1994
Seasonal dynamics of soil water, the annual water balances over a period of 30 years (1960 1990) and the frequency of occurrence of extreme water shortage were quantified with the model 'SWIF' for a Douglas fir stand on a sandy soil in the Netherlands. This information was needed for evaluating the impact of air pollution and water shortage on forest growth, and to calculate chemical budgets. Measurements necessary for model parameterization included rainfall, throughfall, transpiration, soil water content and soil water pressure head. These data are available for 3 years. For the period without measurements, throughfall and potential evapotranspiration were calculated from synoptic weather data with an empirical model. The effect of using synoptic weather data instead of detailed on-site measured data was analysed. The results show that after calibration of the empirical model the simulated annual water balance and seasonal soil water dynamics were well described with synoptic weather data as well as with detailed on-site measured data. The modelled annual water balances for the period 1960-1990 are presented as cumulative frequency distributions. Median values of the major terms of the water balance and the frequency of occurrence of extreme water shortage were derived from these diagrams. Annual median precipitation was 834 ram, calculated median interception loss 317 ram, r alan transpiration 363 mm, median soil water evaporation 32 mm and median vertical drainage at 150 cm depth 195 mm. The sum of the major losses is not equal to median annual precipitation as the median values of the individual terms may occur in different years. Transpiration shows smaller variations (11%) between the years than throughfall (54%) and vertical drainage (112%). Although the median value of transpiration reduction resulting from water stress is low (4%), some years showed extreme water shortage, the highest transpiration reduction being 31% for 1976. Although total transpiration reduction during median years is low, short periods with considerable drought stress occur during these years.
Geoderma, 2003
For a representative measurement of soil water content and its changes at the scale of a forest stand, information about the spatial and temporal variability has to be taken into account. The scale on which single trees and tree species influence the variation in space and time was investigated in a mixed Norway spruce -European beech stand in Lower Austria. On a 0.5 ha plot the volumetric soil water content (VWC) was measured at 194 sample locations along square grids of different spacing, using a Trase1 TDR system with waveguides installed vertically over a soil depth of 0 -30 cm. Discontinuous measurements were taken in approximately 14 day intervals during the growing season of 2000. Semivariogram analysis was used to summarize the spatial variation of VWC at selected dates. Kriging interpolation plots of soil water depletion (recharge) between these dates served to compare extraction (rewetting) patterns to tree (species) distribution. During a long drying cycle in spring, species specific transpiration behaviour turned out to be the main source of variation. Light rainfalls of medium intensity on moderately dry soil caused a rewetting pattern, which reflected the different interception efficiency of the contrasted species resulting from architectural properties. Rain events of high intensity on dry soil led to an erratic distribution pattern of water in the soil due to preferential flow in shrinkage cracks, which had opened up during drying. The effect of tree architecture was largely covered in this case. The extent to which a clear spatial correlation of VWC could be detected varied within a radius of 4 to 20 m, depending on VWC as well as on the drying and rewetting history. D
Geoderma, 2011
Ecological studies require environmental descriptors to establish the response of species or communities to ecological conditions. The soil water resource is an important factor, but it is difficult for plant ecologists to use because of the lack of accessible data. We explored whether collecting a large number of plots with basic soil information within the framework of forest inventories would make it possible to map the soil water holding capacity (SWHC) with sufficient accuracy to predict tree species growth over large areas. We first compared the performance of the available pedotransfer functions (PTFs) and found significant differences in the SWHC prediction quality based on the PTFs selected. We also found that the most efficient class PTFs and continuous PTFs compared had similar performances. However, there was a significant reduction in efficiency when they were applied to soils that were different from those used to calibrate them. With a root mean squared error (RMSE) of 0.046 cm 3 cm -3 (n = 227 horizons), we selected the Al Majou class PTFs to predict the SWHC in the soil horizons described in every plot. Thus, 84% of the measured SWHC variance have been explained in soils that were free of stones (n = 63 plots). We then estimated the soil water holding capacity by integrating the stone content collected at the soil pit scale (SWHC') and both the stone content at the soil pit scale and rock outcrop at the plot scale (SWHC") for the 100,307 forest plots recorded in France within the framework of forest inventories. The SWHC" values were interpolated by kriging to produce a map with a 1-km² cell size, a wider resolution leading to a decrease in map accuracy. The SWHC" values given by the map ranged from 0 to 148 mm for soil down to a depth of 1 m. The RMSE between the map values and plot estimates was 33.9 mm for the entire France, with a prediction accuracy similar for a large range of scale, the best predictions being recorded for soils developed on marl, clay, and hollow silicate rocks, and in flat areas. Finally, the abilities of SWHC' and SWHC" to predict height growth for Fagus sylvatica, Picea abies and Quercus petraea were investigated, and we found that the predictive ability of SWHC" was much better than that of SWHC'. The SWHC" values extracted from the map were significantly related to tree height growth. They explained 10.7% of the height growth index variance for Beech (Fagus sylvatica, n = 866), 14.1% for Sessile oak (Quercus petraea, n = 877), and 10.3% for Norway spruce (Picea abies, n = 2067). These proportions of variance accounted by SWHC" were close to those found for the SWHC" values estimated from the plots (11.5, 11.7, and 18.6% for Fagus sylvatica, Quercus petraea, and Picea abies, respectively). We conclude that SWHC" can be mapped with sufficient accuracy to predict species growth using basic soil parameters collected from inventories plots. Thus, the map could be used just as well for small areas as for large areas, directly or indirectly through water balance indices, to predict forest growth and thus production, today or in the future, in the context of an increasing drought period linked to a global change in climatic conditions.
Soil Biology and Biochemistry, 2006
Our objectives were to determine both spatial and temporal variations in soil respiration of a mixed deciduous forest, with soils exhibiting contrasting levels of hydromorphy. Soil respiration (R S ) showed a clear seasonal trend that reflected those of soil temperature (T S ) and soil water content (W S ), especially during summer drought. Using a bivariate model (RMSE ¼ 1.03), both optimal soil water content for soil respiration (W SO ) and soil respiration at both 10 1C and optimal soil water content (R S10 ) varied among plots, ranging, respectively, from 0.25 to 0.40 and from 2.30 to 3.60 mmol m À2 s À1 . Spatial variation in W SO was related to bulk density and to topsoil N content, while spatial variation in R S10 was related to basal area and the difference in pH measured in water or KCl suspensions. These results offer promising perspectives for spatializing ecosystem carbon budget at the regional scale. r
A vertical water balance model is presented which calculates a set of different water balance parameters (evapotranspiration, interception, runoff and soil water content) for various land covers and in particular for forest stands as daily values. The model is suitable for site specific calculations as well as for regional and large scale estimation. Climatic input data are readily available from weather services. Texture and structure of soils and rooting depth are assessed from soil profiles, while standardized crop and forest stand information characterize the land cover. The HyMo model was validated with continuously measured soil water content data, as well as with lysimeter data over several years in different forest stands and for different crops. Other validations were done with measured runoff data for two catchment areas. A good agreement between simulated and measured data with deviations that are all smaller than 10% gives evidence for its suitability. Results of water balance calculations for beech and spruce stands in Southern Germany are presented. Additionally, examples show that HyMo is a powerful tool for dendroecological analyses because the retrospective estimation of different water balance parameters is possible.
A novel approach in model-based mapping of soil water conditions at forest sites
Forest Ecology and Management, 2009
Knowledge of site-specific water conditions is important in forestland evaluation and fundamental for a sustainable forest management. In Central Europe, traditional site mapping has followed an integrated ecological approach. The assessment of soil water availability is based on overlaying relief and descriptive soil information. It is a relative system referring to an (hypothetical) equilibrium between relief-dependent soil conditions and the potential natural forest association at a given regional climate. Accordingly, the climatic settings are supposed to be constant and are mostly based on long-term means of precipitation and air temperature. However, long-term climate changes, as well as infrequent climatic extremes have not been considered adequately. Furthermore, the feedback of forest management itself on available soil water cannot be addressed. To overcome these shortcomings, we developed an approach in which the soil hydrological model LWF-BROOK90 is organized in a GIS-frame to simulate the daily water fluxes and soil moisture status. Spatially distributed meteorological input data is generated from long-term station data using special regionalization procedures. Model parameterization for soil physical properties by horizon are derived from detailed forest soil maps using pedotransfer functions. Thus, we obtained data on all components of the water balance depending on climate, aspect, slope, vertical soil properties, and stand conditions in a spatial resolution of 25 m  25 m. In addition to the common output of site water balance models, additional indicators were implemented to enable the quantification of 'transpiration stress', 'soil drought stress', and 'excess soil water stress'. Soil water evaluation is based on the number of days exceeding defined thresholds of parameter values. The implemented soil water indices were suitable to reflect relevant differences in the soil water conditions between sites whereas focusing on individual and extreme years rather than on long-term averages seems to be more appropriate for assessing water-related tree growth conditions. The next step will be to produce forest site maps based on such 'stress' indicators. The novel approach provides a more objective description of variable soil water conditions than the currently used mapping approach. Furthermore, it makes spatial hydrological data (e.g. groundwater recharge) available for use beyond forest management.
Knowledge of the relationship between soil water dynamics and tree water use is critical to understanding forest response to environmental change in water-limited ecosystems. However, the dynamics in soil water availability for tree transpiration (T t ) cannot be easily deduced from conventional measurements of soil water content (SWC), notably because T t is influenced by soil water potential (Ψ s ) that, in turn, depends on soil characteristics. Using tree sap flow and water potential and deriving depth-dependent soil water retention curves, we quantified the 'transpirable soil water content' (tSWC) and its seasonal and inter-annual variations in a semiarid Pinus halepensis forest. The results indicated that tSWC varied in time and with soil depth. Over one growing season T t was 57% of rain and 72% of the infiltrated SWC. In early winter, T t was exclusively supported by soil moisture at the top 10 cm (tSWC = 11 mm), whereas in spring (tSWC > 18 mm) and throughout the dry season, source water for T t shifted to 20-40 cm, where the maximum fine root density occurs. Simulation with the soil-plant-atmosphere water and energy transport model MuSICA supported the idea that consistent tSWC at the 20-40 cm soil layer critically depended on limited water infiltration below 40 cm, because of high water retention below this depth. Quantifying tSWC is critical to the precise estimation of the onset and termination of the growing season (when tSWC > 0) in this semi-arid ecosystem. Figure 7. (a) Transpirable soil water content (tSWC, n = 2-3) in three depth layers and precipitation in Yatir forest during 2006-2010 (annual precipitation amounts were 224, 308, 200, 160 and 289 mm, respectively). Droughts during 2008 and 2009 resulted in long intervals (up to 5 months) of zero water availability, ultimately leading to large-scale tree mortality. (b) Zooming in on the linear decline of tSWC in layer III after 30 April. Regression slopes are -0Á012, -0Á011, -0Á012, -0Á011 and -0Á009% d À1 for 2006-2010, respectively (R 2 = 0Á92-0Á97), allowing early estimate of the date of tSWC exhaustion in this forest ecosystem.
Polish Journal of …, 2009
European beech (Fagus sylvatica L.) ranks as one of the most adaptive species among European indigenous trees. Variable interactions between the trees and soil water depend on both phenotypic plasticity of the species and natural conditions. They are controlled through stomatal regulation and the ability of beech trees to accelerate quickly their growth if available resources increase. However, the effect of forest density at various altitudes on the soil water content in beech stands has been studied rather scarcely. Therefore, we monitored soil moisture by means of Time Domain Reflectometry in series of natural and managed stands located on sites representing the lower altitude (200-550 m a.s.l.), middle altitude (550-1050 m a.s.l.) and higher altitude (1050-1300 m a.s.l.) zones of the natural beech belt in the Western Carpathians, Slovakia. Forest stand density, expressed in terms of basal area, i.e. the sum of cross section areas of the tree stems at 1.30 m height, was unchanged in natural stands, but it was reduced by 60% in the shelterwood stands. In the clear-cuts, all trees were removed. Total soil water content (SWC) under forest stands was calculated in mm as the product of soil moisture and soil depth, the latter acquired by electrical resistivity tomography. SWC differences between natural and shelterwood stands of the lower altitude, middle altitude and higher altitude zones averaged 18 mm, 36 mm and-3 mm, respectively. According to the Friedman test on ranks, followed by post-hoc multiple comparison testing, the difference was only significant within the middle altitude zone. In it, soil water consumption by the natural stand was limited only by the hormonally controlled seasonal regulation. The comparatively low water loss in the shelterwood stand resulted from a small rainfall interception by forest canopy and a decreased soil water uptake due to reduced basal area, leaf area index and simple age-size forest structure. In the lower altitude zone, the precipitation deficit and limited extractability of soil water were responsible for the absence of larger SWC differences. As opposed to that, low potential evapotranspiration prevented any noticeable SWC differences within the higher altitude zone.