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Forests are structurally complex ecosystems with several canopy layers, each with distinct functional properties contributing differently to the net ecosystem CO2 exchange. A large number of studies have addressed ecosystem-scale net CO2 fluxes in forests, but only few studies have investigated the role of the forest understory. The goal of this study was to quantify the below-canopy contribution to ecosystem CO2 fluxes of a mixed deciduous forest in Switzerland. Below- and above-canopy eddy-covariance (EC) measurements were made continuously over two years, complemented by within canopy wind and CO2 concentration profile measurements. On an annual basis, the below-canopy fluxes indicated a net carbon source dominated by soil respiration, while the above-canopy fluxes were dominated by tree photosynthesis leading to a net carbon sink. Below-canopy fluxes showed a net carbon sink only in spring, with the early emergence of understory plants before overstory canopy leaf-out. Below-canopy respiration partitioned from the EC measurements agreed well with previous chamber-based soil respiration measurements. However, below- and above-canopy fluxes became decoupled under full canopy closure, thus leading to unaccounted below-canopy fluxes when measured only above the canopy. Wind and CO2 concentration profile measurements supported this finding. Decoupling was independent of low turbulence conditions and decoupled periods could be identified using the relationship between the below- and above-canopy standard deviation in vertical wind velocity. A decoupling correction was applied to the above-canopy measurements during decoupled periods and corrected annual net ecosystem production (NEP) agreed well with independent estimates from biomass inventory combined with models. Overall, the below-canopy fluxes contributed 79% to annual ecosystem respiration, but only 9% to annual ecosystem photosynthesis. The decoupling correction reduced annual NEP for the site from about 760 to 330 g C m−2 yr−1. Our results showed that below-canopy EC measurements are essential in this mixed deciduous forest, and likely in many other forests, to fully understand the carbon dynamics within structurally complex ecosystems.

We outline an approach combining airborne laser scanning (ALS) and imaging spectroscopy (IS) to quantify and assess patterns of tree density (TD) and forest productivity (FP) in a protected heterogeneous alpine forest in the Swiss National Park (SNP). We use ALS data and a local maxima (LM) approach to predict TD, as well as IS data (Airborne Prism Experiment—APEX) and an empirical model to estimate FP. We investigate the dependency of TD and FP on site related factors, in particular on surface exposition and elevation. Based on reference data (i.e., 1598 trees measured in 35 field plots), we observed an underestimation of ALS-based TD estimates of 40%. Our results suggest a limited sensitivity of the ALS approach to small trees as well as a dependency of TD estimates on canopy heterogeneity, structure, and species composition. We found a weak to moderate relationship between surface elevation and TD (R2 = 0.18–0.69) and a less pronounced trend with FP (R2 = 0.0–0.56), suggesting that both variables depend on gradients of resource availability. Further to the limitations faced in the sensitivity of the applied approaches, we conclude that the combined application of ALS and IS data was convenient for estimating tree density and mapping FP in north-facing forested areas, however, the accuracy was lower in south-facing forested areas covered with multi-stemmed trees.

The Weddell Sea sector of the Antarctic Ice Sheet is hypothesized to have made a significant contribution to sea-level rise since the Last Glacial Maximum. Using a numerical flowline model we investigate the controls on grounding line motion across the eastern Weddell Sea and compare our results with field data relating to past ice extent. Specifically, we investigate the influence of changes in ice temperature, accumulation, sea level, ice shelf basal melt, and ice shelf buttressing on the dynamics of the Foundation Ice Stream. We find that ice shelf basal melt plays an important role in controlling grounding line advance, while a reduction in ice shelf buttressing is found to be necessary for grounding line retreat. There are two stable positions for the grounding line under glacial conditions: at the northern margin of Berkner Island and at the continental shelf break. Global mean sea-level contributions associated with these two scenarios are ~50 mm and ~130 mm, respectively. Comparing model results with field evidence from the Pensacola Mountains and the Shackleton Range, we find it unlikely that ice was grounded at the continental shelf break for a prolonged period during the last glacial cycle. However, we cannot rule out a brief advance to this position or a scenario in which the grounding line retreated behind present during deglaciation and has since re-advanced. Better constraints on past ice sheet and ice shelf geometry, ocean temperature, and ocean circulation are needed to reconstruct more robustly past behavior of the Foundation Ice Stream.

The forest and building sector is of major importance in climate change mitigation and therefore construction materials based on forest products are of great interest. While energy efficiency has had a large focus in climate change mitigation in the building sector, the carbon footprint of the construction material is gaining relevance. The carbon footprint of construction materials can vary greatly from one type to another, the building sector is consequently demanding documentation of the carbon footprint of the materials used. Using an environmental product declaration (EPD) is an objective and standardised solution for communicating the environmental impacts of construction products and especially their carbon footprint. Nevertheless, it is challenging to include the features of forest products as pools of carbon dioxide. There is currently a focus on research into methods for the accounting of sequestered atmospheric carbon dioxide and also implementation of these methods into technical standards. This paper reviews the recent research and technical standards in this field to promote a common understanding and to propose requirements for additional information to be included in EPDs of forest-based products. The main findings show the need for reporting the contribution of biogenic carbon to the total on greenhouse gas emissions and removals over the product’s lifecycle. In order to facilitate the implementation of more advanced methods from research, the EPD should also include more detailed information of the wood used, in particular species and origin. ISSN:1971-7458

Geophysical mapping and coring of the central Arctic Ocean seafloor provide evidence for repeated occurrences of ice sheet/ice shelf complexes during previous glacial periods. Several ridges and bathymetric highs shallower than present water depths of ~1000?m show signs of erosion from deep drafting (armadas of) icebergs which originated from thick outlet glaciers and ice shelves. Mapped glacigenic landforms and dates of cored sediments suggest that the largest ice shelf complex was confined to the Amerasian sector of the Arctic Ocean during Marine Isotope Stage (MIS) 6. However the spatial extent of ice shelves can not be well reconstructed from occasional groundings on bathymetric highs. Therefore we apply a statistical approach to provide independent support for an extensive MIS 6 ice shelf complex which previously was inferred only from interpretation of geophysical and geological data. Specifically we assess whether this ice shelf complex comprises a likely source of the deep draft icebergs responsible for the mapped scour marks. The statistical modeling is based on exploiting relations between contemporary Antarctic ice shelves and their local physical environments and the assumption that Arctic Ocean MIS?6 ice shelves scale similarly. Analyzing ice thickness data along the calving front of contemporary ice shelves a peak over threshold method is applied to determine sources of deep drafting icebergs in the Arctic Ocean MIS?6 ice shelf complex. This approach is novel to modeling Arctic paleoglacial configurations. Predicted extreme calving front drafts match observed deep draft iceberg scours if the ice shelf complex is sufficiently large.

Spatial and temporal patterns of forest background (understory) reflectance are crucial for retrieving biophysical parameters of forest canopies (overstory) and subsequently for ecosystem modeling. In this communication, we retrieved seasonal courses of understory normalized difference vegetation index (NDVI) from multiangular Moderate Resolution Imaging Spectroradiometer bidirectional reflectance distribution function (MODIS BRDF)/albedo data. We compared satellite-based seasonal courses of understory NDVI to understory NDVI values measured in different types of forests distributed along a wide latitudinal gradient (65.12°N-31.35°N). Our results indicated that the retrieval method performs well particularly over open forests of different types. We also demonstrated the limitations of the method for closed canopies, where the understory signal retrieval is much attenuated.

Rice straw and chestnut wood were heated between 200 and 1000 °C (T CHAR) to produce Black C 'thermosequences'. The molecular properties of the charred residues were assessed by pyrolysis-GC/MS to investigate the relation between charring intensity and pyrolysis fingerprint. Samples obtained at T CHAR > 500 °C (wood) or >700 °C (straw) gave low quality pyrograms and poor reproducibility because of high thermal stability, but pyrolysis-GC/MS allowed to track the thermal degradation of the main biocomponents (polysaccharides, lignin, methylene chain-based aliphatics, triterpenoids, chlorophyll and proteins) in the lower temperature range, mostly occurring between T CHAR 250 and 500 °C. With increasing T CHAR, the charred residues of these biocomponents lose characteristic functional groups, aromatise and finally condense into non-pyrolysable biomass. The proportions of the pyrolysis products of unspecific origin (benzene, toluene, PAHs, etc.), increase with charring intensity, while the ratios that reflect the abundance of alkyl cross-linkages between aromatic moieties (e.g. benzene/toluene, naphthalene/alkylnaphthalene) decrease. These results provide the guidelines to using pyrolysis-GC/MS for the molecular characterisation of different components in Black C and biochar, which is an important parameter for predicting Black C/biochar behaviour in soil. Results are consistent with earlier studies of these samples using the BPCA (benzenepolycarboxylic acid) method and the ring current-induced 13C benzene chemical shift NMR (Nuclear Magnetic Resonance) approach. Pyrolysis-GC/MS provides more information on molecular structures in the low temperature range (T CHAR ≤ 500 °C) while the BPCA and NMR ring current methods provide more reliable estimations of charring intensity, especially at higher temperatures (T CHAR ≥ 500 °C). © 2012 Elsevier Ltd., This study was partly funded by the Spanish Ministry of Science and Education under the framework of the CONSOLIDER-INGENIO 2010 program TCP (CSD2007-00058).

In order to estimate the influence of plant architectural traits on the erosivity of throughfall we studied throughfall kinetic energy (KE) under tree saplings in a plantation-like experiment in the humid subtropics. Our analyses of rainfall and throughfall KE are based on measurements using calibrated splash cups. Two experiments were carried out, one focusing on density effects and the other testing for species-specific effects and effects of species mixtures. The major architectural traits were measured to characterize sapling morphology. Mixed effects models were used for statistical analysis. In both models, rainfall KE was identified as the most important effect on throughfall KE. Overall, rainfall KE per area was reduced by 59% below the canopy of the studied saplings. We found a significant effect of sapling density on throughfall KE. This is primarily due to the relation between free throughfall and released throughfall. As free throughfall possesses a far higher KE than released throughfall originating from saplings, lower sapling density results in higher total throughfall KE. We also showed that the influence of density on throughfall KE decreases with increasing sapling height due to lateral canopy growth of the saplings. Throughfall KE was significantly different among species. We attribute this to species-specific differences in crown architectural traits. These traits have opposite influence on throughfall KE and interact with each other. Depending on its magnitude, one crown trait can possibly superimpose contrary effects of others. In order to estimate the influence of plant architectural traits on the erosivity of throughfall we studied throughfall kinetic energy (KE) under tree saplings in a plantation-like experiment in the humid subtropics. Our analyses of rainfall and throughfall KE are based on measurements using calibrated splash cups. Two experiments were carried out, one focusing on density effects and the other testing for species-specific effects and effects of species mixtures. The major architectural traits were measured to characterize sapling morphology. Mixed effects models were used for statistical analysis. In both models, rainfall KE was identified as the most important effect on throughfall KE. Overall, rainfall KE per area was reduced by 59% below the canopy of the studied saplings. We found a significant effect of sapling density on throughfall KE. This is primarily due to the relation between free throughfall and released throughfall. As free throughfall possesses a far higher KE than released throughfall originating from saplings, lower sapling density results in higher total throughfall KE. We also showed that the influence of density on throughfall KE decreases with increasing sapling height due to lateral canopy growth of the saplings.Throughfall KE was significantly different among species. We attribute this to species-specific differences in crown architectural traits. These traits have opposite influence on throughfall KE and interact with each other. Depending on its magnitude, one crown trait can possibly superimpose contrary effects of others. © 2012 Elsevier B.V.

To describe the decay stage of coarse woody debris (CWD) a five decay-class system has been introduced and it is currently the most commonly applied. This system is based on visual, geometric and tactile features of the wood in the field; however, a detailed chemical characterization is often missing. Furthermore, the driving mechanisms (particularly substrate quality vs. environmental conditions) of deadwood decay are controversially discussed. Consequently, we investigated how typical major and minor chemical parameters of wood were correlated with the decay stage. The decomposition patterns of Norway spruce (Picea abies (L.) Karst) and European larch (Larix decidua Mill.) CWD of an Alpine setting were analyzed, and how the chemical and physical parameters were affected by the substrate and environmental conditions was checked. Two altitudinal sequences, having a different exposure (north- vs. south-facing sites), were sampled. We measured main biochemical compounds (lignin and cellulose), physical properties (density and water content), element concentrations (C, N, P, K, Ca, Mg, Fe, Mn), and the carbon isotopic signature (δ13C) of living trees and CWD at five decomposition stages (decay classes). Most investigated wood physico-chemical parameters such as wood density, water content, lignin and cellulose and even minor constituents (N, Ca, Mg, P, Fe, Mn) correlated well to the five decay-class system. Some important components, such as the carbon concentration and δ13C, did not vary with increasing decomposition. Our hypothesis that the different substrate should be traceable during CWD decay had to be rejected, although some statistically significant chemical differences between larch and spruce were measured in the living trees. The chosen tree species were probably not different enough to be chemically traceable in the CWD. Already in decay class 1, these differences were zeroed. The site conditions (expressed by the different altitudes and exposure) influenced only some of the investigated parameters, namely lignin, the δ13C isotopic ratio and nutrients such as P, Ca and K.

Describing current, past and future landscapes for inventory and policy making purposes requires classifications capturing variation in, for example, land use and land cover. Typical land cover classifications for such purposes result from a top-down process and rely on expert conceptualisations, and thus provide limited space for incorporating more widely held views of key landscape elements. In this paper we introduce the notion of spatial folksonomies, which we define as a tuple linking a vocabulary of landscape terms through authors and resources to locations. We demonstrate how spatial folksonomies can automatically be created for Switzerland using two text corpora: the Swiss Alpine Club's yearbook for the past 150 years and user generated content from a website describing a wide range of outdoor activities. The spatial folksonomies capture variation in space of the use of nouns describing 96 natural landscape terms (e.g. ridge, forest, mountain, etc.) and allow us to characterise regions and compute similarities. We compare our spatial folksonomies to two traditional land cover/land use classifications (CORINE and Arealstatistik) and demonstrate that despite their very different sources, the approaches capture landscape variation in broadly similar ways. However, our spatial folksonomies provide new insights into how landscapes are described, through for example variation in space, time and through the prism of different activities. We argue that our spatial folksonomies are a novel way of capturing variation closer to the bottom-up understandings of landscape for instance required to describe cultural ecosystem services.

Climate model simulations are routinely compared to observational data sets for evaluation purposes. The resulting differences can be large and induce artifacts if propagated through impact models. They are usually termed “model biases,” suggesting that they exclusively stem from systematic models errors. Here we explore for Switzerland the contribution of two other components of this mismatch, which are usually overlooked: interpolation errors and natural variability. Precipitation and temperature simulations from the RCM COSMO-Community Land Model were compared to two observational data sets, for which estimates of interpolation errors were derived. Natural variability on the multidecadal time scale was estimated using three approaches relying on homogenized time series, multiple runs of the same climate model, and bootstrapping of 30 year meteorological records. We find that although these methods yield different estimates, the contribution of the natural variability to RCM-observation differences in 30 year means is usually small. In contrast, uncertainties in observational data sets induced by interpolation errors can explain a substantial proportion of the mismatch of 30 year means. In those cases, we argue that the model biases can hardly be distinguished from interpolation errors, making the characterization and reduction of model biases particularly delicate. In other regions, RCM biases clearly exceed the estimated contribution of natural variability and interpolation errors, enabling bias characterization and robust model evaluation. Overall, we argue that bias correction of climate simulations needs to account for observational uncertainties and natural variability. We particularly stress the need for reliable error estimates to accompany observational data sets.

Pyrogenic organic matter (PyOM) is considered an important soil carbon (C) sink. However, there are evidences that its addition to soil may induce a priming effect (PE) thus influencing its C abatement potential. The direction, the size and the mechanisms responsible for PyOM induced PE are far from being understood. We collected approximately 650 data points from 18 studies to analyse the characteristics of the PE induced by PyOM. The database was divided between the PE induced on the native soil organic matter and on fresh organic matter. Most of the studies were short-term incubation therefore the projections of findings on the long term may be critical. Our findings indicate that over 1 year PyOM induces an average positive PE of 0.3 mg C g−1 soil on native soil organic matter and a PE of approximately the same size but opposite direction on fresh organic matter. We studied the correlation of PE with several properties of soil, of the added PyOM, and time after PyOM addition. We found that PyOM primes positively the native soil organic matter in the first 20 days while negative PE appears in a later stage. Negative PE was correlated with the soil C content. PyOM characterized by a low C content induced a higher positive PE on native soil organic carbon. No correlation was found between the factors record in our database and the PE induced on the fresh organic matter. We reviewed the mechanisms proposed in literature to explain PE and discussed them based on findings from our meta-analysis. We believe that the presence of a labile fraction in PyOM may trigger the activity of soil microorganisms on the short term and therefore induce a positive PE, while on the long term PyOM may induce a negative PE by promoting physical protection mechanisms.

The growing awareness of biodiversity by forest managers has fueled the demand for information on abiotic and biotic factors that determine spatial biodiversity patterns. Detailed and area-wide environmental data on potential predictors and site-specific habitat characteristics, however, are usually not available across large spatial extents. Recent developments in environmental data acquisition such as the advent of Light Detection And Ranging (LiDAR) remote sensing provide opportunities to characterize site-specific habitat conditions at a high level of detail and across large areas. Here, we used a dataset of regularly distributed local-scale records of vascular plant, bryophyte and snail (Gastropoda) species to model richness patterns in forests across an environmentally heterogeneous region in Central Europe (Switzerland). We spatially predicted species richness based on a set of area-wide environmental factors representing climate, topography, soil pH and remotely sensed vegetation structure. Additionally, we investigated the relationship between species richness and field measures of forest stand structure and composition obtained from National Forest Inventory (NFI) data to identify potential target variables for habitat management. The predictions for species richness were most accurate for snails, followed by bryophyte and vascular plants, with R2 values ranging from 0.37 to 0.07. Besides climate, site-specific factors such as soil pH, indices of topographic position and wetness as well as canopy structure were important for predicting species richness of all three target groups. Several NFI variables were identified as potential target variables for managing snail species richness. Stands with tree species from the genera Fraxinus, Tilia, Ulmus and Acer, for example, showed a positive relationship with snail species richness, as did an increasing overstory cover or higher volumes of deadwood. However, only weak relationships were found between NFI variables and species richness of vascular plants, and none for bryophytes. Our findings support the assumption that besides climate, site-specific habitat factors are important determinants of spatial variation of species richness at the local scale. The strength and direction of the determinants vary with taxa, thus indicating a functional relationship between site conditions and the respective species community.

Soil erosion threatens ecosystem functioning by reducing soil organic carbon stocks or relocating nutrients. A common measure to protect soil against erosion is afforestation. There is growing evidence that mixed-species forest stands have beneficial effects on ecosystem functions (growth rates, nutrient cycling). In addition, species-rich forests tend to have higher and denser crown cover and thus might affect soil erosion. This study investigated the role of tree species richness on throughfall kinetic energy (TKE) as an important part of the soil erosion process and examined the spatial variability of TKE in mixed-species forest stands. The research was conducted within BEF-China, a large-scale forest biodiversity experiment in subtropical China. In summer 2013, 1800 TKE measurements were carried out during five rainfall events. TKE was measured using splash cups and related to tree height, crown base height, number of branches, leaf area index, stem ground diameter and crown area. Our experiment showed that TKE was not influenced by tree species richness at the plot level. This is likely due to the young age of the experimental forest where a dense and high tree canopy has not yet been developed. However, TKE was influenced by neighborhood tree species richness indicating that tree species richness only affected TKE on a small spatial scale within the direct neighborhood in young forests. TKE showed distinct spatial variability. Directly below the first branch of the tree individuals TKE was lowest (430J/m2) while it was highest in the middle of four tree individuals (556J/m2). Mean freefall kinetic energy (FKE) was 480J/m2. Lower TKE below the first branch than FKE can be attributed to low rain drop velocities due to short falling heights. Higher TKE in the middle of four tree individuals than FKE can be ascribed to a larger crown area on which drops can confluence resulting in an increase of drop mass. Furthermore, TKE was positively affected by the number of influencing tree individuals with a 13% increase of TKE from one to four influencing tree individuals. However, further investigation on TKE below mature trees and dense canopies is needed to confirm our findings for later successional stages.

Using a one-dimensional numerical model of ice-stream flow with robust grounding-line dynamics, we explore controls on paleo-ice-stream retreat in Marguerite Bay, Antarctica, during the last deglaciation. Landforms on the continental shelf constrain the numerical model and suggest that retreat was rapid but punctuated by a series of slowdowns. We investigate the sensitivity of ice-stream retreat to changes in subglacial and lateral topography and to forcing processes including sea-level rise, enhanced melting beneath an ice shelf, atmospheric warming, and ice-shelf debuttressing. Our experiments consistently reproduce punctuated retreat on a bed that deepens inland, with retreat-rate slowdowns controlled by narrowings in the topography. Sensitivity experiments indicate that the magnitudes of change required for individual forcing mechanisms to initiate retreat are unrealistically high but that thresholds are reduced when processes act in combination. The ice stream is, however, most sensitive to ocean warming and associated ice-shelf melting, and retreat was most likely in response to external forcing that endured throughout the period of retreat rather than to a single triggering “event.” Timescales of retreat are further controlled by the delivery of ice from upstream of the grounding line. Due to the influence of topography, modeled retreat patterns are insensitive to the temporal pattern of forcing evolution. We therefore suggest that despite regionally similar forcing mechanisms, landscape controls significant contrasts in retreat behavior between adjacent but topographically distinct catchments. Patterns of ice-stream retreat in the past, present, and future should therefore be expected to vary significantly.

Large-scale insect outbreaks can substantially alter the carbon exchange of forests. Currently, British Columbia, Canada, is experiencing the largest mountain pine beetle (MPB, Dendroctonus ponderosae) outbreak ever registered, leaving large areas of forest killed or partially killed. It has been found that some unharvested attacked stands have returned to being a carbon sink within a relatively short time. A three-week field campaign was conducted during the summer of 2010 in one of these MPB-attacked stands, to determine the contributions of different vegetation layers to the overall net ecosystem exchange (NEE) of the stand. Almost all of the mature pine trees in this stand were dead, while there was a relatively rich secondary structure (younger conifer trees not killed by the beetle) and a broadleaf dominated understory. Two independent approaches, the eddy-covariance (EC) approach using seven EC systems distributed vertically on a tower of which six were installed within the canopy and one above the canopy and an ecophysiological (EP) approach based on carbon dioxide (CO2) chamber measurements on foliage and boles were employed in this study. Air-column storage corrected CO2 flux below each measurement level was partitioned into photosynthesis and respiration components. The climatic conditions during the field campaign were dry, and water use efficiency was analyzed while going from moderate to dry conditions. Due to the open-stand structure, approximately 60% of the photosynthetically active radiation reached the 1-m height. The photosynthesis of the living vegetation exceeded the respiration in this stand. The understory was found to have the largest CO2 sink strength in the canopy, while the secondary structure also contributed substantially to the overall CO2 uptake. The overstory, consisting of mainly dead trees, was a weak CO2 source. The EC and EP approaches agreed regarding the vertical distribution of sources and sinks of CO2 in the canopy; however, the magnitude varied between the two approaches. Water use efficiency was relatively high with the daytime average value between 2.3 g C kg−1 H2O close to the ground where the broadleaf vegetation was dominant and 6.5 g C kg−1 H2O where the conifer trees of the secondary structure were located. The secondary structure exhibited greater adjustment to increasingly dry conditions than the broadleaf vegetation.

This study discusses the potential of applying agent-based modeling (ABM) to wood markets. A corresponding model of the wood market of a Swiss canton, consisting of a coupled roundwood and wood fuel market, is presented. The model includes wood-producing agents, such as public foresters and private forest owners, roundwood-consuming agents, such as sawmills, different classes of wood fuel consumers, and in-between wood traders. Other important model elements include agent interaction and negotiation, execution and scheduling structures, and agent adaptation mechanisms. Two sets of scenarios demonstrate the model's power for scenario exploration. The first set of scenarios analyzes the effects of an excess and scarce supply of wood on both markets. The second set looks for the optimal number of roundwood agents in the market from the perspective of the various stakeholders involved. Taking a more in-depth view of important design decisions and their pros and cons, this study argues that ABM offers new opportunities for the explorative study of wood markets as a result of these markets' special characteristics.

Experimental forest plantations to study biodiversity–ecosystem functioning (BEF) relationships have recently been established in different regions of the world, but subtropical biomes have not been covered so far. Here, we report about the initial survivorship of 26 tree species in the first such experiment in subtropical China. In the context of the joint Sino–German–Swiss Research Unit “BEF-China,” 271 experimental forest plots were established using 24 naturally occurring tree species and two native commercial conifers. Based on the survival inventories carried out in November 2009 and June 2010, the overall survival rate was 87 % after the first 14 months. Generalized mixed-effects models showed that survival rates of seedlings were significantly affected by species richness, the species’ leaf habit (deciduous or evergreen), species identity, planting date, and altitude. In the first survey, seedling establishment success decreased with increasing richness levels, a tendency that disappeared in the second survey after replanting. Though evergreen species performed less well than deciduous species with establishment rates of 84 versus 93 % in the second survey, their planting success exceeded the general expectation for subtropical broad-leaved evergreen species. These results have important implications for establishing mixed-species plantations for diversity conservation and improvement of ecosystem functioning in the Chinese subtropics and elsewhere. Additional costs associated with mixed-species plantations as compared to conventional plantations also demonstrate the potential of upscaling BEF experiments to large-scale afforestation projects. Experimental forest plantations to study biodiversity-ecosystem functioning (BEF) relationships have recently been established in different regions of the world, but subtropical biomes have not been covered so far. Here, we report about the initial survivorship of 26 tree species in the first such experiment in subtropical China. In the context of the joint Sino-German-Swiss Research Unit "BEF-China," 271 experimental forest plots were established using 24 naturally occurring tree species and two native commercial conifers. Based on the survival inventories carried out in November 2009 and June 2010, the overall survival rate was 87 % after the first 14 months. Generalized mixed-effects models showed that survival rates of seedlings were significantly affected by species richness, the species' leaf habit (deciduous or evergreen), species identity, planting date, and altitude. In the first survey, seedling establishment success decreased with increasing richness levels, a tendency that disappeared in the second survey after replanting. Though evergreen species performed less well than deciduous species with establishment rates of 84 versus 93 % in the second survey, their planting success exceeded the general expectation for subtropical broad-leaved evergreen species. These results have important implications for establishing mixed-species plantations for diversity conservation and improvement of ecosystem functioning in the Chinese subtropics and elsewhere. Additional costs associated with mixed-species plantations as compared to conventional plantations also demonstrate the potential of upscaling BEF experiments to large-scale afforestation projects.

Estimation of total leaf area (LAT) is important to express biochemical properties in plant ecology and remote sensing studies. A measurement of LAT is easy in broadleaf species, but it remains challenging in coniferous canopies. We proposed a new geometrical model to esti- mate Norway spruce LAT and compared its accuracy with other five published methods. Further, we assessed vari- ability of the total to projected leaf area conversion factor (CF) within a crown and examined its implications for remotely sensed estimates of leaf chlorophyll content (Cab). We measured morphological and biochemical properties of three most recent needle age classes in three vertical can- opy layers of a 30 and 100-year-old spruce stands. Newly introduced geometrical model and the parallelepiped model predicted spruce LAT with an error \5 % of the average needle LAT, whereas two models based on an elliptic approximation of a needle shape underestimated LAT by up to 60 %. The total to projected leaf area conversion factor varied from 2.5 for shaded to 3.9 for sun exposed needles and remained invariant with needle age class and forest stand age. Erroneous estimation of an average crown CF by 0.2 introduced an error of 2-3 l gc m -2 into the crown averaged Cab content. In our study, this error represents 10-15 % of observed crown averaged Cab range (33-53 l gc m -2 ). Our results demonstrate the importance of accurate LAT estimates for validation of remotely sensed estimates of Cab content in Norway spruce canopies.

Spectral and directional reflectance properties of coniferous forests are known to differ from those of broadleaf forests. Many reasons have been proposed for this, including differences in the optical properties of leaves and shoots, the latter being considered the basic unit in radiative transfer modeling of a coniferous canopy. Unfortunately, very little empirical data is available on the spectrodirectional scattering properties of shoots. Here, we present results of angular measurements (using an ASD FieldSpec 3 spectroradiometer mounted on LAGOS) of ten Scots pine shoots in the spectral range 400--2000 nm. The shoots were found to scatter anisotropically with most of the radiation reflected back into the hemisphere where the radiation source was positioned. To describe the measured directional scattering pattern, we propose a phase function consisting of isotropic and Lambertian scattering components. Next, we used the proposed scattering phase function in a Monte Carlo radiative transfer model. Angular reflectance of a modeled horizontally homogeneous shoot canopy has, due to shoot scattering anisotropy, an enhanced “dark spot” as compared with a canopy composed of isotropic scatterers and a quantitatively similar leaf canopy.

Procedure to develop an agent-based model of a Swiss forest wood fuel market It is helpful to develop agent-based model based on a structured procedure. The chosen traditional software engineering approach is mainly composed of five phases: 1) the analysis of the observed system; 2) the model development; 3) the detailed design; 4) the actual software implementation; and 5) the model's evaluation. The different phases are briefly described by the respective goals, tasks and expected results. This contribution shows the development of a Swiss forest wood fuel market with specific examples for each phase. The essential work steps and intermediate results are demonstrated from the start to a fully developed agent-based model. Finally it is demonstrated how to carry through scenario analyses for the modeled forest wood fuel market. The simulation example shows first that, as is to be expected, a reduction of the wood supply leads to increasing forest wood fuel prices. Second, it shows how the decision behavior of wood suppliers can additionally modify the price of forest wood fuel in a situation of scarce supply, whereas this effect is smaller in a situation of balanced supply and demand.

In the past two decades, the eddy covariance technique has been used for an increasing number of methane flux studies at an ecosystem scale. Previously, most of these studies used a closed path setup with a tunable diode laser spectrometer (TDL). Although this method worked well, the TDL has to be calibrated regularly and cooled with liquid nitrogen or a cryogenic system, which limits its use in remote areas. Recently, a new closed path technique has been introduced that uses off-axis integrated cavity output spectroscopy that does not require regular calibration or liquid nitrogen to operate and can thus be applied in remote areas. In the summer of 2008 and 2009, this eddy covariance technique was used to study methane fluxes from a tundra site in northeastern Siberia. The measured emissions showed to be very dependent on the fetch area, due to a large contrast in dry and wet vegetation in between wind directions. Furthermore, the observed short-and long-term variation of methane fluxes could be readily explained with a nonlinear model that used relationships with atmospheric stability, soil temperature, and water level. This model was subsequently extended to fieldwork periods preceding the eddy covariance setup and applied to evaluate a spatially integrated flux. The model result showed that average fluxes were 56.5, 48.7, and 30.4 nmol CH4 m-2 s-1 for the summers of 2007 to 2009. While previous models of the same type were only applicable to daily averages, the method described can be used on a much higher temporal resolution, making it suitable for gap filling. Furthermore, by partitioning the measured fluxes along wind direction, this model can also be used in areas with nonuniform terrain but nonetheless provide spatially integrated fluxes. Copyright 2011 by the American Geophysical Union.

[1] Rock-ice avalanches larger than 1 × 106 m3 are high-magnitude, low-frequency events that may occur in all ice-covered, high mountain areas around the world and can cause extensive damage if they reach populated regions. The temporal and spatial evolution of the seismic signature from two events was analyzed, and recordings at selected stations were compared to numerical model results of avalanche propagation. The first event is a rock-ice avalanche from Iliamna volcano in Alaska which serves as a “natural laboratory” with simple geometric conditions. The second one originated on Aoraki/Mt. Cook, New Zealand Southern Alps, and is characterized by a much more complex topography. A dynamic numerical model was used to calculate total avalanche momentum, total kinetic energy, and total frictional work rate, among other parameters. These three parameters correlate with characteristics of the seismic signature such as duration and signal envelopes, while other parameters such as flow depths, flow path and deposition geometry are well in agreement with observations. The total frictional work rate shows the best correlation with the absolute seismic amplitude, suggesting that it may be used as an independent model evaluation criterion and in certain cases as model calibration parameter. The good fit is likely because the total frictional work rate represents the avalanche's energy loss rate, part of which is captured by the seismometer. Deviations between corresponding calculated and measured parameters result from site and path effects which affect the recorded seismic signal or indicate deficiencies of the numerical model. The seismic recordings contain additional information about when an avalanche reaches changes in topography along the runout path and enable more accurate velocity calculations. The new concept of direct comparison of seismic and avalanche modeling data helps to constrain the numerical model input parameters and to improve the understanding of (rock-ice) avalanche dynamics.

[1] From past studies it has been known that the Pacific Decadal Oscillation (PDO) shifted toward a positive mode in 1976 and a new climate regime occurred that produced a warming of the mean annual and seasonal temperatures and associated increases in cloud cover and precipitation in the North Pacific including Alaska. In this study, this climate shift is examined with regard to the variations in surface solar radiation before and after 1976 during the period 1961–2005. The results show greatest changes occurring in the southeast region in winter with a significant rise of 1.67% yr−1 during 1961–1975 before the shift and a nonsignificant decline of −1.07% yr−1 during 1977–1991 after the shift. In addition to the variations in solar radiation that occurred after 1976, the PDO and the solar radiation time series show common changes around 1989 and 1998. Thus, these two variables are compared to assess the strength of their relationship. The results show a good to moderate correlation with a maximum found in winter in Big Delta (interior region). The Pacific North American (PNA) circulation pattern is also strongly correlated with the solar radiation, with a maximum in winter in Anchorage (south-central region). In addition, a close relationship is found between cloud cover and solar radiation, particularly in the south-central and southwest regions. These results suggest that circulation patterns and associated cloud cover changes may play a large role, especially during wintertime, in the variations in the surface solar radiation in these regions of Alaska.

[1] This study aims at giving a methodical description of the use of gridded output from a regional climate model (RCM) for the calculation of glacier mass balance distribution for the perimeter of the Swiss Alps. The mass balance model runs at daily steps and 100 m spatial resolution, while the regional model (REMO) RCM provides daily grids (� 18 km resolution) of dynamically downscaled reanalysis data. A combination of interpolation techniques and simple subgrid parameterizations is applied to bridge the gap in spatial resolution and to obtain daily input fields of air temperature, global radiation, and precipitation. Interpolation schemes are a key element and thus we test different interpolators. For validation, computed mass balances are compared to stake measurements and time series (1979–2003) of observed mass balance. The meteorological input fields are compared to measurements at weather stations. The applied inverse distance weighting introduces systematic biases due to spatial autocorrelation, whereas thin plate splines preserve the characteristics of the RCM output. While summer melt at point locations on several glaciers is well reproduced by the model, accumulation is mostly underestimated. These systematic shifts are correlated to biases of the meteorological input fields. Time series of mass balance obtained from the model run agree well with observed time series. We conclude that the gap in spatial resolution is not a major drawback, given that interpolators and parameterizations are selected upon detailed considerations. Biases in RCM precipitation are a major source for the observed underestimations in mass balance and have to be corrected prior to operational use of the presented approach.

Wood Science and Technology, 44 (1), ISSN:0043-7719, ISSN:1432-5225

[1] The surface solar radiation (SSR) is an important factor influencing the local and global energy budget. However, information on the spatial and temporal variation of SSR is limited. A more commonly available measure, which may provide such information, is the diurnal temperature range (DTR). In this study we analyze the relationship between DTR and SSR in Europe between 1970 and 2005 on seasonal and decadal scale. When comparing the mean anomalies time series composed of 31 pairs of sites with long-term SSR and DTR measurements, we found a correlation coefficient of 0.87 in the annual mean and between 0.61 and 0.92 in the seasonal mean anomalies. When investigating the individual pairs of SSR and DTR individually, we found that local correlations are mostly lower than the European mean and that they decrease rapidly in seasons and latitudes with low incident angles and at high alpine altitude. The highest correlation on local and seasonal scales seems to be connected with the variability of the large-scale circulation in Europe. The output of 11 simulations of current generation regional climate models over Europe confirms the strong relationship between SSR and DTR. The seasonal dependence of the relationship is well reproduced, but the absolute values of DTR and SSR are mostly too low. The pattern of decrease (dimming) and increase (brightening) in SSR and DTR was not reproduced in the modeled time series. There is still strong evidence from both models and observations that DTR is a reliable representative of SSR.

Forest fire management practices are highly dependent on the proper monitoring of the spatial distribution of the natural and man-made fuel complexes at landscape level. Spatial patterns of fuel types as well as the three-dimensional structure and state of the vegetation are essential for the assessment and prediction of forest fire risk and fire behaviour. A combination of the two remote sensing systems, imaging spectrometry and light detection and ranging (LiDAR), is well suited to map fuel types and properties, especially within the complex wildland–urban interface. LiDAR observations sample the spatial information dimension providing explicit geometric information about the structure of the Earth's surface and super-imposed objects. Imaging spectrometry on the other hand samples the spectral dimension, which is sensitive for discrimination of surface types. As a non-parametric classifier support vector machines (SVM) are particularly well adapted to classify data of high dimensionality and from multiple sources as proposed in this work. The presented approach achieves an improved land cover mapping adapted to forest fire management needs. The map is based on a single SVM classifier combining the spectral and spatial information dimensions provided by imaging spectrometry and LiDAR.

[1] The current permafrost distribution on Livingston Island, South Shetland Islands, maritime Antarctic, was investigated using electrical resistivity tomography, refraction seismics, and shallow borehole temperatures. The field sites include different geological and geomorphological settings, including ice cored moraines and bedrock sites with debris covers of different thickness. Two-dimensional geophysical inversion schemes were used to analyze spatial heterogeneity at field sites and to detect isolated occurrences of ground ice. Results confirm that permafrost is widespread on Livingston Island, with high ice content in ice cored moraines and little in the cracks and fissures of frozen bedrock. Specific electrical resistivity values range from 10,000–40,000 ohm-m (frozen unconsolidated material) to 1500–10,000 ohm-m (frozen quartzite/shale). Combining seismic P wave velocities and specific electrical resistivities, a typical ‘‘roof-type’’ distribution was found with maximum resistivities coinciding with P wave velocities around 3000 m/s and decreasing resistivities for both increasing and decreasing velocities.

While budgets for agri-environmental policy in OECD countries are rapidly increasing with current policy reforms, information about the locally varying demands for policies implemented at various levels of government remains scarce. In this study, a median voter framework is used to analyse the demand for landscape management services based on the expenditures of sub-federal governments for two decentralized landscape management programmes in Switzerland. Furthermore, based on the expenditures for one cantonal and one national agri-environmental scheme, it is determined whether the cantonal scheme resulted in a more demand-oriented pattern of expenditures than the national scheme. The median voter model estimates suggest a high-income elasticity and a low-price elasticity of demand for landscape management services. Contrary to expectations, both the cantonal and national expenditures significantly reflected cantonal variations in proxies of the demand for landscape management services.

During May 2003 the Department of Energy's Atmospheric Radiation Measurement Program conducted an Intensive Operations Period (IOP) to measure the radiative effects of aerosol and clouds. A suite of both in situ and remote sensing measurements were available to measure aerosol and cloud parameters. This paper has three main goals: First, it focuses on comparison between in situ retrievals of the radiatively important drop effective radius r(sub e) and various satellite, airborne, and surface remote sensing retrievals of the same parameter. On 17 May 2003, there was a fortuitous, near-simultaneous sampling of a stratus cloud by five different methods. The retrievals of r(sub e) agree with one another to within approx.20%, which is approximately the error estimate for most methods. Second, a methodology for deriving a best estimate of r(sub e) from these different instruments, with their different physical properties and sampling volumes, is proposed and applied to the 17 May event. Third, the paper examines the response of r(sub e) to changes in aerosol on 3 days during the experiment and examines the consistency of remote sensing and in situ measurements of the effect of aerosol on r(sub e). It is shown that in spite of the generally good agreement in derived r(sub e), the magnitude of the response of r(sub e), to changes in aerosol is quite sensitive to the method of retrieving r(sub e) and to the aerosol proxy for cloud condensation nuclei. Nonphysical responses are sometimes noted, and it is suggested that further work needs to be done to refine these techniques.