@article{ZimmermannZimmermannLarketal.2010,
  author    = {Zimmermann, Beate and Zimmermann, Alexander and Lark, Richard M. and Elsenbeer, Helmut},
  title     = {Sampling procedures for throughfall monitoring : a simulation study},
  issn      = {0043-1397},
  doi       = {10.1029/2009wr007776},
  year      = {2010},
  abstract  = {What is the most appropriate sampling scheme to estimate event-based average throughfall? A satisfactory answer to this seemingly simple question has yet to be found, a failure which we attribute to previous efforts' dependence on empirical studies. Here we try to answer this question by simulating stochastic throughfall fields based on parameters for statistical models of large monitoring data sets. We subsequently sampled these fields with different sampling designs and variable sample supports. We evaluated the performance of a particular sampling scheme with respect to the uncertainty of possible estimated means of throughfall volumes. Even for a relative error limit of 20\%, an impractically large number of small, funnel-type collectors would be required to estimate mean throughfall, particularly for small events. While stratification of the target area is not superior to simple random sampling, cluster random sampling involves the risk of being less efficient. A larger sample support, e.g., the use of trough-type collectors, considerably reduces the necessary sample sizes and eliminates the sensitivity of the mean to outliers. Since the gain in time associated with the manual handling of troughs versus funnels depends on the local precipitation regime, the employment of automatically recording clusters of long troughs emerges as the most promising sampling scheme. Even so, a relative error of less than 5\% appears out of reach for throughfall under heterogeneous canopies. We therefore suspect a considerable uncertainty of input parameters for interception models derived from measured throughfall, in particular, for those requiring data of small throughfall events.},
  language  = {en}
}
@article{HasslerLarkMilneetal.2011,
  author    = {Haßler, Sibylle Kathrin and Lark, Richard M. and Milne, A. E. and Elsenbeer, Helmut},
  title     = {Exploring the variation in soil saturated hydraulic conductivity under a tropical rainforest using the wavelet transform},
  series = {European journal of soil science},
  volume    = {62},
  journal   = {European journal of soil science},
  number    = {6},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1351-0754},
  doi       = {10.1111/j.1365-2389.2011.01400.x},
  pages     = {891 -- 901},
  year      = {2011},
  abstract  = {Saturated hydraulic conductivity (Ks) of the soil is a key variable in the water cycle. For the humid tropics, information about spatial scales of Ks and their relation to soil types deduced from soil map units is of interest, as soil maps are often the only available data source for modelling. We examined the influence of soil map units on the mean and variation in Ks along a transect in a tropical rainforest using undisturbed soil cores at 06 and 612 cm depth. The Ks means were estimated with a linear mixed model fitted by residual maximum likelihood (REML), and the spatial variation in Ks was investigated with the maximum overlap discrete wavelet packet transform (MODWPT). The mean values of Ks did not differ between soil map units. The best wavelet packet basis for Ks at 06 cm showed stationarity at high frequencies, suggesting uniform small-scale influences such as bioturbation. There were substantial contributions to wavelet packet variance over the range of spatial frequencies and a pronounced low frequency peak corresponding approximately to the scale of soil map units. However, in the relevant frequency intervals no significant changes in wavelet packet variance were detected. We conclude that near-surface Ks is not dominated by static, soil-inherent properties for the examined range of soils. Several indicators from the wavelet packet analysis hint at the more dominant dynamic influence of biotic processes, which should be kept in mind when modelling soil hydraulic properties on the basis of soil maps.},
  language  = {en}
}