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In recent years the harmonization of methods in the frame of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) operating under the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP) has been intensified. Among the C-actions of the FutMon project (LIFE07 ENV/D/000...
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... of growth, defoliation, forest health and ground vegetation monitoring and research. In the outer part, different collectors are installed e.g., throughfall collectors for precipitation other than snow (gutter-type), throughfall collectors for snow (cornet-type), baskets for litterfall, and soil solution sampler devices (suction cup lysimeters - Fig. 1). The main tree species in the plot is Scots Pine (Pinus sylvestris L.). The stand belongs to the Vaccinio myrtilli-Pinetum forest type, is 80 to 120 years old, and canopy openness is 18%. The prevailing soil unit is Dystric Cambisols (FAO 1998) developed from fluvioglacial gravels and sands. The site is slightly exposed to the ...
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Citations
... In ICP Forests QA/QC procedures were introduced, using internal quality controls based on ion balance and conductivity checks and external quality controls, with mandatory ring tests for the laboratories at least every 2 years (Ferretti et al., 2009;König et al., 2013). Furthermore, Zlindra et al. (2011) assessed the comparability of the deposition samplers used in different countries between each other and versus a standardized collector shaped following the rules used for meteorological gauges. Results showed good agreement in the amount and the chemical composition of precipitation between all national collectors and the harmonized one. ...
Atmospheric nitrogen and sulfur deposition is an important effect of atmospheric pollution and may affect forest ecosystems positively, for example enhancing tree growth, or negatively, for example causing acidification, eutrophication, cation depletion in soil or nutritional imbalances in trees. To assess and design measures to reduce the negative impacts of deposition, a good estimate of the deposition amount is needed, either by direct measurement or by modeling. In order to evaluate the precision of both approaches and to identify possible improvements, we compared the deposition estimates obtained using an Eulerian model with the measurements performed by two large independent networks covering most of Europe. The results are in good agreement (bias <25%) for sulfate and nitrate open field deposition, while larger differences are more evident for ammonium deposition, likely due to the greater influence of local ammonia sources. Modeled sulfur total deposition compares well with throughfall deposition measured in forest plots, while the estimate of nitrogen deposition is affected by the tree canopy. The geographical distribution of pollutant deposition and of outlier sites where model and measurements show larger differences are discussed.
... The mixed forest site was equipped with eight systematically distributed, fixed-funnel collectors (0.23 m in diameter), installed 140 cm above ground level. In addition, throughfall was collected using ten systematically distributed gutter collectors (3-m long tube, 4-cm in diameter, with three, 87-cm long and 0.9-cm wide slits in lines), with the upper portion installed 0.60 m above the forest floor, draining directly into polyethylene tanks, which were used as collection containers (Zlindra et al. 2011). The total sampling area in the 0.25 ha plot was 0.52 m 2 (the receiving area of each funnel collector was 415 cm 2 and of each gutter 185 cm 2 ). ...
... The results of this and other comparable studies clearly demonstrate that canopy interception by forests is extremely variable and difficult to measure (Asadian and Weiler 2009). To achieve a higher spatial representativeness of the throughfall measurements and to improve canopy interception estimates in forests with a large canopy heterogeneity, a higher number of throughfall collectors should be used (Zlindra et al. 2011). In addition, the rainfall pattern must be considered when selecting the type and number of collecting devices, since the coefficient of variation increases with decreasing throughfall depth (Zimmermann et al. 2010). ...
Urban forests provide important ecosystem services. In terms of hydrological benefits, forest ecosystems in urban environments represent qualitative and quantitative filter for rainwater. We quantified the canopy interception in relation to urban forest stand structure and rainfall intensity in an urban transect of the mixed (upland) forest in the city centre, towards a riparian pine forest and a floodplain hardwood forest in the City of Ljubljana, Slovenia. Bulk precipitation in open areas and throughfall were measured with fixed rainfall collectors in each forest. Stemflow was estimated from a review of relevant literature. We found that canopy interception in selected urban forests was mainly affected by tree species composition and other stand structure variables, such as canopy cover and tree dimensions. Average annual canopy interception was highest in the mixed forest (18.0% of bulk precipitation), while the riparian pine forest had the lowest level (3.9% of bulk precipitation) and the floodplain hardwood forest had the intermediate level for interception (7.1% of bulk precipitation). The mixed forest exhibited the stand structure factors that contributed to the highest canopy interception among the studied forests: high assemblage of dominant coniferous trees, denser canopy cover and the highest growing stock. Furthermore, rainfall intensity has proven to be an important factor for the seasonal partitioning (comparing the leafed and leafless period) of canopy interception. A better understanding of precipitation interception processes in urban forests is needed to assist urban forest managing and planning, aiming at maximizing canopy interception for the mitigation of stormwater runoff and flooding in urbanized watershed.
... Comparability and meaningful interpretation of data derived from long-term monitoring across time require representative measurements based on harmonized methods and a statistically sound design (Clarke et al. 2010;Cools and de Vos 2011;Ferretti 2010Ferretti , 2011Ferretti et al. 2014. Within this context, the spatial representativity and comparability of atmospheric deposition measurements are crucial issuesfor exposure and effect assessments Erisman et al. 2003;Lorenz and Granke 2009;Žlindra et al. 2011). Clarke et al. (2010) found large differences in results of different types of technical samplers and that several factors might influence the measurements, among them the number and surface area of samplers used as well as their placing in the stands and the extent of the area equipped with collectors. ...
Key messageMoss surveys provide spatially dense data on environmental concentrations of heavy metals and nitrogen which, together with other biomonitoring and modelling data, can be used for indicating deposition to terrestrial ecosystems and related effects across time and areas of different spatial extension. ContextFor enhancing the spatial resolution of measuring and mapping atmospheric deposition by technical devices and by modelling, moss is used complementarily as bio-monitor. AimsThis paper investigated whether nitrogen and heavy metal concentrations derived by biomonitoring of atmospheric deposition are statistically meaningful in terms of compliance with minimum sample size across several spatial levels (objective 1), whether this is also true in terms of geostatistical criteria such as spatial auto-correlation and, by this, estimated values for unsampled locations (objective 2) and whether moss indicates atmospheric deposition in a similar way as modelled deposition, tree foliage and natural surface soil at the European and country level, and whether they indicate site-specific variance due to canopy drip (objective 3). Methods
Data from modelling and biomonitoring atmospheric deposition were statistically analysed by means of minimum sample size calculation, by geostatistics as well as by bivariate correlation analyses and by multivariate correlation analyses using the Classification and Regression Tree approach and the Random Forests method. ResultsIt was found that the compliance of measurements with the minimum sample size varies by spatial scale and element measured. For unsampled locations, estimation could be derived. Statistically significant correlations between concentrations of heavy metals and nitrogen in moss and modelled atmospheric deposition, and concentrations in leaves, needles and soil were found. Significant influence of canopy drip on nitrogen concentration in moss was proven. Conclusion
Moss surveys should complement modelled atmospheric deposition data as well as other biomonitoring approaches and offer a great potential for various terrestrial monitoring programmes dealing with exposure and effects.
... Comparability and meaningful interpretation of data derived from long-term monitoring across time require representative measurements based on harmonized methods and a statistically sound design (Clarke et al. 2010;Cools and de Vos 2011;Ferretti 2010Ferretti , 2011Ferretti et al. 2014. Within this context, the spatial representativity and comparability of atmospheric deposition measurements are crucial issuesfor exposure and effect assessments Erisman et al. 2003;Lorenz and Granke 2009;Žlindra et al. 2011). Clarke et al. (2010) found large differences in results of different types of technical samplers and that several factors might influence the measurements, among them the number and surface area of samplers used as well as their placing in the stands and the extent of the area equipped with collectors. ...
... The estimation of this parameter, in turn, critically depends on the quality of throughfall estimates (Germer et al., 2006;Lloyd et al., 1988). To optimize throughfall sampling, a number of studies investigated the effect of sample size, support (i.e. the shape of a collector), and sampling design (Cuartas et al., 2007;Holwerda et al., 2006;Kimmins, 1973;Kostelnik et al., 1989;Price and Carlyle-Moses, 2003;Puckett, 1991;Regalado, 2010, 2014;Rodrigo and Àvila, 2001;Ziegler et al., 2009;Zimmermann and Zimmermann, 2014;Zimmermann et al., 2010;Zlindra et al., 2011). Somewhat surprisingly, comparatively little attention has been paid to the role of the extent, i.e. the size of the area under study. ...
... To date the importance of the extent for the sampling of representative estimates of mean throughfall has not been adequately assessed. This is partly because previous studies on throughfall sampling strategies almost exclusively worked with empirical data (Holwerda et al., 2006;Kimmins, 1973;Kostelnik et al., 1989;Price and Carlyle-Moses, 2003;Puckett, 1991;Regalado, 2010, 2014;Rodrigo and Àvila, 2001;Ziegler et al., 2009;Zlindra et al., 2011). Empirical sampling approaches, however, cannot be used to assess the role of the extent because the sampling usually involves only one extent, a single plot position, and a limited sample size. ...
... The laboratory results are checked for internal consistency based on the conductivity, the ion balance, the concentration of total N and the sodium to chloride (Na/Cl) ratio, and analyses are repeated if suspicious values occur (Mosello et al., 2005(Mosello et al., , 2008ICP Forests, 2010). The quality assurance and control (QA/QC) procedures further include the use of control charts for internal reference material to check long-term comparability within national laboratories, as well as participation in periodic laboratory ring tests (e.g. ) and field inter-comparisons (Draaijers et al., 2001;Zlindra et al., 2011a) to check the international comparability. ...
Atmospheric deposition to forests has been monitored within the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) with sampling and analyses of bulk precipitation and throughfall at several hundred forested plots for more than 15 years. The current deposition of inorganic nitrogen (nitrate and ammonium) and sulphate is highest in central Europe as well as in some southern regions. We compared linear regression and Mann-Kendall trend analysis techniques often used to detect temporal trends in atmospheric deposition. The choice of method influenced the number of significant trends. Detection of trends was more powerful using monthly data compared to annual data. The slope of a trend needed to exceed a certain minimum in order to be detected despite the short-term variability of deposition. This variability could to a large extent be explained by meteorological processes, and the minimum slope of detectable trends was thus similar across sites and many ions. The overall decreasing trends for inorganic nitrogen and sulphate in the decade to 2010 were about 2% and 6%, respectively. Time series of about 10 and 6 years were required to detect significant trends in inorganic nitrogen and sulphate on a single plot. The strongest decreasing trends were observed in western central Europe in regions with relatively high deposition fluxes, whereas stable or slightly increasing deposition during the last 5 years was found east of the Alpine region as well as in northern Europe. Past reductions in anthropogenic emissions of both acidifying and eutrophying compounds can be confirmed due to the availability of long-term data series but further reductions are required to reduce deposition to European forests to levels below which significant harmful effects do not occur according to present knowledge.
... In the LIFE+ FutMon project, a harmonisation experiment is cur rently being carried out, in which national deposition samplers are compared with standardised deposition samplers on forest monitoring plots throughout Europe. A pre liminary paper on this experiment is pu blished in this journal (Zlindra et al. 2011). ...
Data from existing monitoring programmes such as ICP Forests, ICP Integrated Monitoring and EMEP, as well as from large-scale international projects such as CarboEurope IP and NitroEurope, can be used to answer questions about the impacts of air pollution and climate change on forest ecosystems and the feedbacks of forest to climate. However, for full use to be made of the available data, a number of questions need to be answered related to the availability, accessibility, quality and comparability of the data. For example, how can these databases be accessed, e.g., freely, over the internet, on request, by authorisation? How should intellectual property rights be protected, while improving access to data? What possibilities exist for harmonisation? Which quality assurance/quality control (QA/QC) procedures have been used and for how long? These and other relevant questions are discussed
Among the main concerns of the researchers is the comparability of the analysis methods,
in order to highlight possible errors. Several statistical approaches and graphical tools are available
to investigate sources of analytical error and for decision-making. In this article, we present an
operative protocol for the comparison of the precision for two laboratories with the same quantitative
analytical methods. This paper describes the importance of achieving sequential stages, including
experimental design, familiarization with the method of optimal research analysis, quality evaluation,
selection of sample, definition of acceptability criteria. Sample measurement, data analysis and
evaluation, final decision and reporting are also discussed and exemplified.
The reason for performing a comparison experiment is to estimate the type and magnitude of
systematic error between two laboratories with the same method and to judge if the two laboratories
are identical within the inherent imprecision methods or within preset analytical quality
specifications. Finally, the purpose was to check if same ranges of concentrations and fluxes of
pollutants are obtained using the same methods of analysis, but in two different labs.
Količina, oblika in časovna razporeditev padavin so izrednega pomena za gozdne ekosisteme, saj pomembno vplivajo na njihovo preskrbo z vodo. Hkrati so gozdovi pomembni z vidika prestrezanja padavin in zadrževanja vode v tleh, s čimer prispevajo k uravnavanju količine vodnih virov v porečju. Natančnejše poznavanje poraz-delitve padavin v gozdnih ekosistemih je vse pomembnejše tudi zaradi podnebne spremenljivosti, ki vpliva na spremembe padavinskega režima ter pogostnost in intenzivnost izrednih padavinskih dogodkov. Namen naše raziskave je bil analizirati padavine na osmih ploskvah intenzivnega monitoringa gozdov v Sloveniji v letih od 2004 do 2013, na katerih smo z rednimi dvotedenskimi meritvami spremljali padavine na prostem, prepuščene padavine, odtok po deblu ter sestojne padavine. Ugotavljali smo, v kolikšni meri je količina sestojnih padavin v gozdu odvisna od geografske lege, reliefa in mešanosti drevesnih vrst. Primerjali smo tudi padavine na prostem s padavinami najbližje postaje ARSO. Količina padavin na ploskvah se je zelo razlikovala zaradi razgibanega površja in splošne porazdelitve padavin v Sloveniji. Letne prepuščene padavine na ploskvah so znašale od 77 % do 103 % padavin na prostem. Letni odtok po deblu na ploskvah s prevladujočo bukvijo je bil od 2 % do 15 % padavin na prostem. Letne sestojne padavine na ploskvah so v povprečju znašale 94 % padavin na prostem in so naraščale z nadmorsko višino ploskev. Padavine na prostem ter na najbližjih postajah ARSO so se večinoma dobro ujemale, razen na ploskvah Fondek v Trnovskem gozu in Tratice na Pohorju, ki sta v topografsko razgibanih gorovjih. V primeru nerazpoložljivosti podatkov o padavinah v topografsko razgibanih območjih je potrebna previdnost pri uporabi podatkov z najbližje postaje ARSO. Jasne povezave med količino sestojnih padavin in mešanostjo drevesnih vrst nismo ugotovili, saj je nabor ploskev v raziskavi majhen, hkrati pa so geografsko tako oddaljene, da na sestojne padavine bolj vpliva splošna porazdelitev padavin v Sloveniji. Za ugotavljanje vpliva mešanosti drevesnih vrst na sestojne padavine bi morali spremljati padavine na majhnem območju s čim bolj enotno topografijo, orografskimi dejavniki ter na več ploskvah z različnimi deleži drevesnih vrst.
Temporal and spatial distribution of precipitation is of great importance for forest ecosystems, as it affects their water supply. At the same time, forests are regulating water flows and affecting the water resources availability in catchments by intercepting precipitation and soil water retention. More detailed information about precipitation distribution in forest ecosystems is necesarry due to climate change, which contributes to changes in precipitation regime and frequency and intensity of extreme precipitation events. The aim of this study was to analyze the precipitation at eight forest monitoring plots in Slovenia from 2004 to 2013, where regular biweekly measurements of precipitation in the open, throughfall, stemflow and net precipitation was preformed. Specifically , we were interested in finding out to what extend the net precipitation in forests is affected by geographical location, altitude and tree species mixture. In addition, open field precipitation was compared to the nearest station of the Slovenian Environmental Agency (ARSO). The precipitation amounts differed among the plots due to compex terrain and general spatial precipitation distribution in Slovenia. Mean annual precipitation on plots ranged from 77 % to 103 % of pricipation in the open. Mean annual stemflow on plots with prevailing beech ranged from 2 % to 15 % of precipitation in the open. Mean annual net precipitation on plots were 94 % of precipitation in the open and were increasing with the altitude. The agreement between open field precipitation and the precipitation on ARSO stations was generally good, except for the Fondek in Trnovski gozd and Tratice on Pohorje Mountains plots, which are located in mountainous regions with compex terrain.In case of unavailabe precipitation data in regions with complex topography, caution is needed when applying data from the nearest ARSO stations. Direct link between net precipitation and tree species mixtrue was not confirmed due to small number of forest monitoring plots. Furthermore, the plots are geographically so remote that the net precipitation is largely affected by general spatial distribution of precipitation in Slovenia. In order to assess the influence of tree species mixture on net precipitation in forests, study in smaller areas with homogene topography and orography should be preformed including a larger number of forest monitoring plots with diverse shares of tree species.
Atmospheric deposition is an important source of macro- and micronutrients to the forest and also the most important channel for input of long-range air pollutants. This chapter describes the methods used for the determination of atmospheric deposition, especially in rain and snow, in forest ecosystems, including samplers for open-field bulk precipitation, throughfall, and stemflow. These measurements can be used to quantify deposition to forests, to evaluate trends in pollutant inputs, and as inputs to modeling of canopy exchange processes, acidification and eutrophication. A major difficulty in throughfall measurement is high spatial and temporal variations, so that great care must be taken to ensure that samples are representative for the forest stand. Care must also be taken to minimize chemical and biological transformations in the samples. Deposition measurements have contributed to policy development and will continue to do so.
