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Tree fecundity and recruitment have not yet been quantified at scales needed to anticipate biogeographic shifts in response to climate change. By separating their responses, this study shows coherence across species and communities, offering the strongest support to date that migration is in progress with regional limitations on rates. The southeastern continent emerges as a fecundity hotspot, but it is situated south of population centers where high seed production could contribute to poleward population spread. By contrast, seedling success is highest in the West and North, serving to partially offset limited seed production near poleward frontiers. The evidence of fecundity and recruitment control on tree migration can inform conservation planning for the expected long-term disequilibrium between climate and forest distribution., Proceedings of the National Academy of Sciences of the United States of America, 119 (3), ISSN:0027-8424, ISSN:1091-6490

Indirect climate effects on tree fecundity that come through variation in size and growth (climate-condition interactions) are not currently part of models used to predict future forests. Trends in species abundances predicted from meta-analyses and species distribution models will be misleading if they depend on the conditions of individuals. Here we find from a synthesis of tree species in North America that climate-condition interactions dominate responses through two pathways, i) effects of growth that depend on climate, and ii) effects of climate that depend on tree size. Because tree fecundity first increases and then declines with size, climate change that stimulates growth promotes a shift of small trees to more fecund sizes, but the opposite can be true for large sizes. Change the depresses growth also affects fecundity. We find a biogeographic divide, with these interactions reducing fecundity in the West and increasing it in the East. Continental-scale responses of these forests are thus driven largely by indirect effects, recommending management for climate change that considers multiple demographic rates., Nature Communications, 12, ISSN:2041-1723

Large-scale environmental sequencing efforts have transformed our understanding of the spatial controls over soil microbial community composition and turnover. Yet, our knowledge of temporal controls is comparatively limited. This is a major uncertainty in microbial ecology, as there is increasing evidence that microbial community composition is important for predicting microbial community function in the future. Here, we use continental- and global-scale soil fungal community surveys, focused within northern temperate latitudes, to estimate the relative contribution of time and space to soil fungal community turnover. We detected large intra-annual temporal differences in soil fungal community similarity, where fungal communities differed most among seasons, equivalent to the community turnover observed over thousands of kilometers in space. inter-annual community turnover was comparatively smaller than intra-annual turnover. Certain environmental covariates, particularly climate covariates, explained some spatial–temporal effects, though it is unlikely the same mechanisms drive spatial vs. temporal turnover. However, these commonly measured environmental covariates could not fully explain relationships between space, time and community composition. These baseline estimates of fungal community turnover in time provide a starting point to estimate the potential duration of legacies in microbial community composition and function.

Environmental seismology is the discipline that uses ambient noise to detect and to measure geomorphic processes. The basic principle relies on the unique seismic signal, in terms of excited frequencies and amplitudes, generated by such processes which is then propagated and recorded to sensors (geophones). Recent developments of this technique are interesting for geomorphology because there is evidence that it can be used to study processes that are rare and difficult to measure, such as bedload transport in rivers. This is of particular importance for quantify bedload flux in proglacial streams. This paper focuses on using this method to quantify bedload export from an Alpine valley glacier. At present, there is no time-continuous measurement of bedload export in such settings. This is because objective measurement of bedload flux is a challenge task for both theoretical and practical reasons. Theoretically, the high variability of bedload transport means that measurements need to be continuous to identify when it happens and with which intensity. Practically, in order to know how to sample the signal through time, you need to know its variance a priori, which is commonly unsteady, and therefore needs to be sampled in order to know how to sample it. Direct manual sampling (e.g. with Helley-Smith samplers) have a serious disadvantage in this sense. Existing indirect methods (e.g. hydrophones and plate geophones) allow collection of continuous data but, at the same time, their installation can be difficult and expensive and they need to be carefully calibrated against manual samplings.In the present study we used seismic data collected by out-of-stream geophones to infer bedload flux along an entire melt season (June - September) at the Glacier d’Otemma proglacial forefield, south-western Swiss Alps. Raw seismic data were inverted into sediment flux following the methodology developed in Dietze et al. (2019), to produce the first continuous dataset of bedload export from an Alpine glacier. The inversion model has been calibrated using statistical (i.e. sensitivity analysis) and direct (i.e. in situ active seismic survey) approaches.

Desert research has a bold track record in deciphering the evolution of landforms. While iconic objects such as inselbergs, yardangs, wadis or dune fields have attracted the attention of scientists for decades and inspired them to develop numerous formation concepts, it is the actual processes, which are suggested to govern their formation, that are usually quite hard to survey as they happen in nature. This amiguitity is due to the often unpredictable, event based, rapid yet episodic nature of their occurrence. While dedicated devices for measuring these processes inevitably exist, they are either confronted with a small spatial footprint (point measurement) or temporal discontinuousity (time lapse data), or even both of these drawbacks. As a consequence, important processes like flash floods, bedload agitation, mass movement on hillslopes, thermal weathering, dune migration rate and mechanism, or averaged information about ground moisture change, substrate rheology, and temperature diffusion can be studied as they happen under natural conditions only in exceptional cases.Here I summarise recent developments from the field of environmental seismology, an emerging discipline that studies the seismic signals emitted by Earth surface processes, with a focus on existing and potential applications to desert environments. I present seismic approaches to detecting, tracking and quantifying flash floods and the sediment they convey, provide an overview of the capabilites of seismology to survey hillslope activity at the catchment scale, and discuss the potential to monitor surface and subsurface activity at the plot scale. The overarching aim of the contribution is to foster a discussion about potential research questions that could be tackled in future joint (i.e., established and seismic sensor) instrumentation projects.

Noise pollution can reduce the ability of urban protected areas to provide a refuge for people and habitat for wildlife. Amidst an unprecedented global pandemic, it is unknown if the changes in human activity have significantly impacted noise pollution in metropolitan parks. We tested the hypothesis that reduced human activity associated with the COVID-19 pandemic lockdowns would lead to reduced sound levels in protected areas compared with non-pandemic times. We measured sound levels in three urban protected areas in metropolitan Boston, MA (USA) at three time periods: in the fall and summer before the pandemic, immediately after the government-imposed lockdown in March 2020 when the trees were leafless, and during the beginning of reopening in early June 2020 when the trees had leaves. At all time periods, sound levels were highest near major roads and demonstrated a logarithmic decrease further from roads. At the two protected areas closest to the city center, sound levels averaged 1–3 dB lower during the time of the pandemic lockdown. In contrast, at the third protected area, which is transected by a major highway, sound levels were 4–6 dB higher during the time of the pandemic, likely because reduced traffic allowed vehicles to travel faster and create more noise. This study demonstrates that altered human levels of activity, in this case associated with the COVID-19 pandemic, can have major, and in some cases unexpected, effects on the levels of noise pollution in protected areas.

Macro-turbulent flows (i.e., coherent flow structures reaching through the whole water column), have not been studied widely in northern seasonally frozen rivers during both open-channel and ice-covered flow conditions. Thus, we aim: (1) to detect and compare the macro-turbulent flow, both at open-channel and ice-covered flow conditions, (2) to explore spatial variation of macro-turbulent flow characteristics within a meander bend, and (3) to detect the effects of near-bed layer velocity fluctuation on bedload transport during differing overall flow conditions. The analyses are based on 5&ndash, 10 min-long acoustic Doppler current profiler (ADCP) measurements from a subarctic river. The ice-covered low flow, and open-channel higher and lower flow conditions were measured over the period of 2016 to 2020. This study found that macro-turbulent flow existed at all measurement locations under both open-channel and ice-covered flow conditions. Macro-turbulent flow was most consistent and obvious in the streamwise velocity component, and in particular at the inlet and outlet of the investigated meander bend. During all seasons, the near-bed velocities consistently exceeded the sufficient amount for sediment transport. At inlet and outlet areas, the greatest near-bed velocity fluctuation across the critical threshold for sediment transport coincided with the measurement times having frequent macro-turbulent flow.

Rock glaciers are typically regarded as periglacial features and their dynamics are supposed to be driven by ice content. Under ongoing global warming we expect these structures and dynamics to change and at least decay. This would be especially the case of rock glaciers in climate-sensitive high mountains of the Tibetan plateau, like in the Nyainqêntanglha range. Despite the similar past and present periglacial climatic conditions in this region, rock glaciers are only formed in a few, specific valleys. With this study, we aim to provide insights into the environmental conditions under which rock glaciers are formed and maintained, to be able to better understand how they will respond to changing boundary conditions, imposed by global warming.To assess “what makes a rock glacier?” we studied such a feature in the Qugaqie basin, at 5500 m a.s.l. To describe the structure and the dynamics of this active rock glacier we applied several methods (geomorphological mapping, geophysics, remote sensing) and we incorporated catchment area properties such as geology, water and sediment sources. Mapping of the geomorphology, the geology and surface material properties characterizes the external structure of the rock glacier. The internal structure, like the active layer zone and the existence of ice, is described by electrical resistivity tomography (ERT). To investigate the surface dynamics of the rock glaciers, we quantify displacement rates using Interferometric Synthetic Aperture Radar (InSAR) time-series analysis. To gain insight to internal deformation dynamics we use environmental seismology, allowing for detection and location of crack signals within the rock glacier. The seismic network also allows tracking rock falls at the head scarp and continuously monitoring glaciofluvial patterns. We find that the singularity of the presence of the studied rock glacier is most likely related to a specific melange of the geological structures, former glaciation of the valley, catchment size and shape and especially water availability.

High resolution topographic models generated from repeat unmanned aerial vehicle (UAV) surveys and structure from motion (SfM) are increasingly being used to investigate landscape changes and geomorphic processes. Traditionally, accurate UAV surveys require the use of independently measured ground control points or highly accurate camera position measurements. However, in addition to accuracy in an absolute sense (how well modeled topography matches real topography), model quality can be expressed as accuracy in a comparative sense (the degree to which two models match each other). We present a simple SfM workflow for calculating pairs or sets of models with a high comparative accuracy, without the need for ground control points or a dGNSS equipped UAV. The method is based on the automated detection of common tie points in stable portions of the survey area and, compared to a standard SfM approach without ground control, reduces the level of change detection in our surveys from several meters to 10-15 cm. We apply this approach in a multi-year monitoring campaign of an 8 km stretch of coastal cliffs on the island of Rügen, Germany. We are able to detect numerous mass wasting events as well as bands of more diffuse erosion in chalk sections of the cliff. Both the cliff collapses and the diffuse erosion appear to be strongly influenced by antecedent precipitation over seasonal timescales, with much greater activity during the winter of 2017-2018, following an above average wet summer, than during the subsequent two winters, which both followed relatively dry summers. This points to the influence of subsurface water storage in modulating cliff erosion on Rügen.

Cliff failure is a fundamental process shaping many coastlines worldwide. Improved insight into direct links between cliff failure and forcing mechanisms requires precise information on the timing of individual failures, which is difficult to obtain with conventional observation methods for longer stretches of coastline. Here we use seismic records and auxiliary data spanning 25 months to precisely identify and locate 81 failure events along the 8.6‐km‐long chalk cliff coast of Jasmund, on Germany's largest island, Rügen. The subminute precision of event timing allows the linkage of individual failures to triggers over a wide range of relevant time scales. We show that during the monitoring interval, marine processes were negligible as a trigger of cliff failure, although still being important for the removal of resulting deposits. Instead, cliff failure was associated with terrestrial controls on rock moisture. Most failures occurred when water caused a state transition of the cliff forming chalk, from solid to liquid. Water content was modulated by (i) subsurface flow toward the cliff, (ii) rain onto the cliff, and (iii) condensation of atmospheric moisture, leading to clustered failures preferentially during the night. Seasonal water availability, controlled by plant activity, imposed an annual cycle of cliff failure, and wetter and drier than average years imposed a month‐long legacy effect on cliff failure dynamics. Similar terrestrial control mechanisms may also be relevant for other coastal chalk cliffs, in addition to already investigated marine triggers.

High-latitude rivers are commonly covered by ice for up to one third of the year. Our understanding of the effects of ice on channel morphodynamics and bedload transport is hindered by the difficulties of sensing through the ice and dangers of field work on thin ice or during ice break-up. To avoid this drawback, we used seismic signals to interpret processes and quantify water and sediment fluxes. Our objective was to determine seasonal differences in hydraulics and bedload sediment transport under ice-covered versus open-channel flow conditions using a small seismic network and to provide a first-order estimation of sediment flux in a Fennoscandian river. Our study reach was on a straight, low-gradient section of the Savar River in northern Sweden. Interpretations of seismic signals, from a station 40 m away from the river, and inverted physical models of river stage and bedload flux indicate clear seasonal differences between ice-covered and open-channel flow conditions. Diurnal cycles in seismic signals reflecting turbulence and sediment transport are evident directly after ice break-up. Analysis of seismic signals of ice-cracking support our visual interpretation of ice break-up timing and the main ice break-up mechanism as thermal rather than mechanical. Assuming the bulk of sediment moves during ice break-up and the snowmelt flood, we calculate a minimum annual sediment flux of 56.2 +/- 0.7 t/km(2), which drastically reduces the uncertainty from previous estimates (0-50 t/km(2)) that exclude ice-covered or ice break-up periods.

A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-22025-2

Rockfalls are an essential geomorphic process and an important natural hazard in steep landscapes across the globe. Seismic monitoring can provide precise information on the timing, location and event anatomy of rockfalls, parameters that are otherwise hard to constrain. By pairing data from 49 seismically detected rockfalls in the Lauterbrunnen Valley, Swiss Alps, with independent information about potential triggers during autumn 2014 and spring 2015, we are able to (i) analyse the evolution of single rockfalls and their common properties, (ii) identify seasonally changing activity hotspots, (iii) and explore temporal activity patterns at different scales, ranging from months to minutes, to quantify relevant trigger mechanisms. Seismic data allows the classification of rockfall activity into three distinct phenomenological types and can be used to discern multiple rock mass releases from the same spot, identify rockfalls that trigger further rockfalls and resolve modes of subsequent talus slope activity. In contrast to findings based on methods with longer integration times, rockfall in the monitored limestone cliff is not spatially uniform but shows a downward shift of rock mass release spots by 33 m per month over the year, most likely driven by a continuously lowering water table. Freeze-thaw-transitions account for only 5 out of the 49 rockfalls whereas 19 rockfalls were triggered by rainfall events, with a peak lag time of 1 h. Another 17 rockfalls were triggered by diurnal temperature changes and occurred during the coldest hours of the day as well as during the highest temperature change rates. This study is thus the first one to show direct links between proposed rockfall triggers and the spatio-temporal distribution of rockfalls under natural conditions, and extends existing models by providing seismic observations of the rockfall process prior to the first rock mass impacts.

Rockfall in deglaciated mountain valleys is perhaps the most important post-glacial geomorphic process for determining the rates and patterns of valley wall erosion. Furthermore, rockfall poses a significant hazard to inhabitants and motivates the monitoring for rockfall occurrence in populated areas. Traditional rockfall detection methods, such as aerial photography and Terrestrial Laser Scanning (TLS) data evaluation provide constraints on the location and released volume of rock, but have limitations due to significant time lags or integration times between surveys, and deliver limited information on rockfall triggering mechanisms and the dynamics of individual events. Environmental seismology, the study of seismic signals emitted by processes at the Earth's surface, provides a complementary solution to these shortcomings. This approach is limited amongst others by the strength of the signals emitted by a source and their transformation and attenuation towards receivers. To test the ability of seismic methods to identify and locate small rockfalls, and to characterise their dynamics, we surveyed a 2.16 km2 large, near vertical cliff section of the Lauterbrunnen Valley in the Swiss Alps with a TLS and six broadband seismometers. During 37 days in autumn 2014, ten TLS-detected rockfalls with volumes ranging from 0.053 ± 0.004 to 2.338 ± 0.085 m3 were independently detected and located by the seismic approach, with a deviation of 81−29+59 m (about 7 % of the average inter-station distance of the seismometer network). Further potential rockfalls were detected outside the TLS-surveyed cliff area. The onset of individual events can be determined within a few milliseconds, and their dynamics can be resolved into distinct phases, such as detachment, free fall, intermittent impact, fragmentation, arrival at the talus slope and subsequent slope activity. The small rockfall volumes in this area require significant supervision during data processing: 2175 initially picked potential events reduced to 511 potential events after applying automatic rejection criteria. The 511 events needed to be inspected manually to reveal 19 short earthquakes and 37 potential rockfalls, including the ten TLS-detected events. Rockfalls do not show a relationship to released seismic energy or peak amplitude at this spatial scale due to the dominance of process-inherent factors, such as fall height, degree of fragmentation and distribution, and subsequent talus slope activity. The combination of TLS and environmental seismology provides a detailed validation of seismic detection of small volume rockfalls, and revealed unprecedented temporal, spatial and geometric details about rockfalls in steep mountainous terrain.

The crucial role of stone pavements in arid environments for aeolian or alluvial processes and as numerical dating tools is increasingly acknowledged. This role is based on the assumption that stone pavements are stable landforms, formed gradually over time and predominantly by vertical processes. However, this is challenged by evidence of stone-pavement clast reworking or burial. Bimodal, mostly slope aspect-symmetrical clast orientation is a frequent phenomenon in various study areas. It implies that stone pavements may be influenced by unidirectional lateral processes besides vertical ones. Here, the finding of lateral processes contributing to stone-pavement evolution is supported by numerical modelling and physical experiments. These unequivocally show that unconcentrated overland flow can transport clasts to form a closely packed stone mosaic with characteristics similar to those of natural stone pavements. The commonly observed length-axes orientation angle of 40 ± 14° for natural stone-pavement clasts is consistently reproduced by angle-dependent force equilibrium. Monte Carlo runs confirm the natural scatter and allow characterization of the control parameters of clast orientation. The model explains up to 70% of the natural variance. It is further validated by flume experiments, which confirm model predictions of single object orientation angles. Experiments with multiple objects yield artificial stone pavements with properties similar to those found in the field. The unidirectional lateral process acting on natural stone pavements requires the presence of a vesicular horizon. This underlines the tight genetic coupling of this common epipedon feature and the clast cover. The presented findings highlight the role of stone pavements as process and environment proxies. However, stone pavements represent information since the last surface disturbance only. This has to be considered when using them as age indicators. Copyright © 2013 John Wiley & Sons, Ltd.

Substantial uncertainty surrounds how forest ecosystems will respond to the simultaneous impacts of multiple global change drivers. Long-term forest dynamics are sensitive to changes in tree mortality rates; however, we lack an understanding of the relative importance of the factors that affect tree mortality across different spatial and temporal scales. We used the US Forest Service Forest Inventory and Analysis database to evaluate the drivers of tree mortality for eastern temperate forest at the individual-level across spatial scales from tree to landscape to region. We investigated 13 covariates in four categories: climate, air pollutants, topography, and stand characteristics. Overall, we found that tree mortality was most sensitive to stand characteristics and air pollutants. Different functional groups also varied considerably in their sensitivity to environmental drivers. This research highlights the importance of considering the interactions among multiple global change agents in shaping forest ecosystems.

On Lanzarote (Canary Islands) Quaternary Saharan dust and weathered local volcanic material were trapped in Miocence to Pliocene valleys dammed by younger volcanic edifices. These sediments show sequences of alternating reddish/clayey and loess-like yellowish/silty material. In order to investigate if reddish/clayey layers contain material derived from local pedogenesis and if so, which pedogenetic processes were active, we performed sedimentological, micromorphological and environmental magnetic analyses. The analyses demonstrate that these layers contain material derived from local soils. These soils were characterised by clay formation, rubefication and the formation of superparamagnetic particles during periods of enhanced soil moisture. Thus, they can serve as natural archives in order to reconstruct the terrestrial palaeoclimatic history of Lanzarote. The distribution of soil material in the profiles shows that cold periods of the Late Quaternary were characterised by more humid conditions than today. Using palaeontological remains and a comparison with recent soils on Tenerife, we can roughly estimate maximal palaeoprecipitation values during more humid periods.

Plant populations migrating in response to climate change will have to colonize established communities. Even if a population disperses to a new region with a favorable climate, interactions with other species may prevent its establishment and further spread. The potential of these species to grow along with residents will be a critical factor controlling their response to climate change. To determine the capacity of migrating species to colonize established communities we conducted extensive long-term transplant experiments where potential tree migrant species, i.e. species within ‘migration range,’ were planted side by side with resident ones. Potential immigrants were selected to be representative species of their native communities. For both groups, residents and potential migrants (17 species), we compared their growth response along gradients in soil moisture and light availability. Rather than manipulate climate directly, we exploited natural microclimatic gradients and the fluctuations in climate that occurred during the 5-year experiment. Experimental results were used to estimate growth in the context of novel climate and relevant establishment factors. Results suggest that potential immigrant species had similar growth rates in the new environment than those from resident species ensuring their ability to establish in the area. However, contrary to our expectations, the soil moisture requirements for the immigrant group were similar to those of the resident species. These results could have major implications for vegetation changes under the predicted drier climate for the region. If it is the case that neither resident species nor potential migrants are able to maintain stable populations, the region may experience a decline in local biodiversity.

EuroAmerican land use and its legacies have transformed forest structure and composition across the United States (US). More accurate reconstructions of historical states are critical to understanding the processes governing past, current, and future forest dynamics. Gridded (8x8km) estimates of pre-settlement (1800s) forests from the upper Midwestern US (Minnesota, Wisconsin, and most of Michigan) using 19th Century Public Land Survey (PLS) records provide relative composition, biomass, stem density, and basal area for 26 tree genera. This mapping is more robust than past efforts, using spatially varying correction factors to accommodate sampling design, azimuthal censoring, and biases in tree selection. We compare pre-settlement to modern forests using Forest Inventory and Analysis (FIA) data, with respect to structural changes and the prevalence of lost forests, pre-settlement forests with no current analogue, and novel forests, modern forests with no past analogs. Differences between PLSS and FIA forests are spatially structured as a result of differences in the underlying ecology and land use impacts in the Upper Midwestern United States. Modern biomass is higher than pre-settlement biomass in the northwest (Minnesota and north-eastern Wisconsin, including regions that were historically open savanna), and lower in the east (eastern Wisconsin and Michigan), due to shifts in species composition and, presumably, average stand age. Modern forests are more homogeneous, and ecotonal gradients are more diffuse today than in the past. Novel forest assemblages represent 29% of all FIA cells, while 25% of pre-settlement forests no longer exist in a modern context. Lost forests are centered around the forests of the Tension Zone, particularly in hemlock dominated forests of north-central Wisconsin, and in oak-elm-basswood forests along the forest-prairie boundary in south central Minnesota and eastern Wisconsin. Novel FIA forest assemblages are distributed evenly across the region, but novelty shows a strong relationship to spatial distance from remnant forests in the upper Midwest, with novelty predicted at between 20 to 60km from remnants, depending on historical forest type. The spatial relationships between remnant and novel forests, shifts in ecotone structure and the loss of historic forest types point to significant challenges to land managers if landscape restoration is a priority in the region. The spatial signals of novelty and ecological change also point to potential challenges in using modern spatial distributions of species and communities and their relationship to underlying geophysical and climatic attributes in understanding potential responses to changing climate. The signal of human settlement on modern forests is broad, spatially varying and acts to homogenize modern forests relative to their historic counterparts, with significant implications for future management.

Desert pavements are widespread landforms of arid environments. They consist of a monolayer of clasts at the surface, associated with an underlying unit of eolian fines. In some situations, buried desert pavements can be observed, which is interpreted as a change in the environmental conditions. Therefore, it is believed that desert pavements represent important paleoenvironmental sediment archives, especially for arid environments, where natural archives of past environments are rare. To better understand the formation process of desert pavements and to enable the paleoenvironmental interpretation of these valuable sediment archives, reliable chronologies are of crucial importance. Thus, OSL dating was applied to samples from well-developed desert pavements in two different study areas, the Cima Volcanic Field, eastern Mojave Desert, USA, and the desert of northeastern Badia, Jordan. To test the suitability of the sediments for OSL dating, the luminescence characteristics of the fine- and coarse-grain quartz fraction are described and compared. Finally, first OSL ages are presented.

Summary � Relationships between leaf traits and carbon assimilation rates are commonly used to predict primary productivity at scales from the leaf to the globe. We addressed how the shape and magnitude of these relationships vary across temporal, spatial and taxonomic scales to improve estimates of carbon dynamics. � Photosynthetic CO2 and light response curves, leaf nitrogen (N), chlorophyll (Chl) concentration and specific leaf area (SLA) of 25 grassland species were measured. In addition, C3 and C4 photosynthesis models were parameterized using a novel hierarchical Bayesian approach to quantify the effects of leaf traits on photosynthetic capacity and parameters at different scales. � The effects of plant physiological traits on photosynthetic capacity and parameters varied among species, plant functional types and taxonomic scales. Relationships in the grassland biome were significantly different from the global average. Within-species variability in photosynthetic parameters through the growing season could be attributed to the seasonal changes of leaf traits, especially leaf N and Chl, but these responses followed qualitatively different relationships from the across-species relationship. � The results suggest that one broad-scale relationship is not sufficient to characterize ecosystem condition and change at multiple scales. Applying trait relationships without articulating the scales may cause substantial carbon flux estimation errors.

Earth system processes exhibit complex patterns across time, as do the models that seek to replicate these processes. Model output may or may not be significantly related to observations at different times and on different frequencies. Conventional model diagnostics provide an aggregate view of model–data agreement, but usually do not identify the time and frequency patterns of model–data disagreement, leaving unclear the steps required to improve model response to environmental drivers that vary on characteristic frequencies. Wavelet coherence can quantify the times and timescales at which two time series, for example time series of models and measurements, are significantly different. We applied wavelet coherence to interpret the predictions of 20 ecosystem models from the North American Carbon Program (NACP) Site-Level Interim Synthesis when confronted with eddy-covariance-measured net ecosystem exchange (NEE) from 10 ecosystems with multiple years of available data. Models were grouped into classes with similar approaches for incorporating phenology, the calculation of NEE, the inclusion of foliar nitrogen (N), and the use of model–data fusion. Models with prescribed, rather than prognostic, phenology often fit NEE observations better on annual to interannual timescales in grassland, wetland and agricultural ecosystems. Models that calculated NEE as net primary productivity (NPP) minus heterotrophic respiration (HR) rather than gross ecosystem productivity (GPP) minus ecosystem respiration (ER) fit better on annual timescales in grassland and wetland ecosystems, but models that calculated NEE as GPP minus ER were superior on monthly to seasonal timescales in two coniferous forests. Models that incorporated foliar nitrogen (N) data were successful at capturing NEE variability on interannual (multiple year) timescales at Howland Forest, Maine. The model that employed a model–data fusion approach often, but not always, resulted in improved fit to data, suggesting that improving model parameterization is important but not the only step for improving model performance. Combined with previous findings, our results suggest that the mechanisms driving daily and annual NEE variability tend to be correctly simulated, but the magnitude of these fluxes is often erroneous, suggesting that model parameterization must be improved. Few NACP models correctly predicted fluxes on seasonal and interannual timescales where spectral energy in NEE observations tends to be low, but where phenological events, multi-year oscillations in climatological drivers, and ecosystem succession are known to be important for determining ecosystem function. Mechanistic improvements to models must be made to replicate observed NEE variability on seasonal and interannual timescales.

Slope deposits, which veil entire slopes or large parts of them in a rather uniform manner (cover beds), are ubiquitous in the subdued mountains of Central Europe. Here we provide an overview of the current state of knowledge on these deposits. The Central European cover beds are divided into (1) the upper layer that is ubiquitously distributed and displays a relatively constant thickness; (2) the intermediate layer the distribution of which is mainly restricted to flat relief, to slope depressions, and to lee-ward facing slopes; and (3) the basal layer, which is rather widespread again. Both the upper and intermediate layer contain intermixed loess, whereas the basal layer is free of loess and typically has a high bulk density. Aside from the loess content, the composition of the layers differs, reflecting varying portions of crushed and chemically weathered rock allocated from up-slope. This causes notable diversity depending on bedrock and, thus, induces remarkable regional differences. Cover beds were mainly formed by periglacial gelifluction. The upper layer formed in the Late Glacial possibly during several short episodes of activity. In contrast, the underlying layers may be diachronous; nevertheless, they display recurring vertical sequences. This is probably due to the fact that loess-free layers usually could not deposit as long as there was loess in the environs, which may have been inherited from older deposits. Thus, the last phase of surface wash, during which older loess was removed, determines the age of the lower layers.

In the north of the island of Lanzarote (Canary Islands, Spain), two palaeosols from different sites were baked by overlying lava flows. Using red thermoluminescence (RTL) dating, late Middle Pleistocene ages were obtained, both varying around 170 ka thus indicating the simultaneity of the volcanic events. Blue thermoluminescence dating using different measuring techniques of the same sample material from one site (the Mala dune) yields somewhat lower ages, varying around 125 ka. However, this result is not in contradiction with the RTL age since anomalous fading was detected, expected to cause a significant underestimation of blue thermoluminescence results. Electron spin resonance dating from land snails overlying the lava flow yielded ages between 204 and 123 ka. Although this dispersion is rather large for material originating from the same stratigraphic horizon, it has to be taken into account that the amount of sample material and thus signal intensity was very low. Furthermore, small measured sample quantities are very vulnerable to dosimetric inhomogenities in the surrounding material, being a further source of uncertainty. Thus, these ESR ages bracketing the RTL age are a further support for a late Middle Pleistocene age of the lava flow. The Middle Pleistocene RTL ages of about 170 ka fill a conspicuous gap in the volcanic chronostratigraphy of Lanzarote, demonstrating that post-erosional volcanism on Lanzarote was obviously more continuous during the Middle and Late Quaternary than known before. Thus, these results demonstrate the potential of RTL and ESR dating to improve the timing of the Quaternary volcanism of the Canary Islands.

Forests are one of Earth's critical biomes. They have been shown to respond strongly to many of the drivers that are predicted to change natural systems over this century, including climate, introduced species, and other anthropogenic influences. Predicting how different tree species might respond to this complex of forces remains a daunting challenge for forest ecologists. Yet shifts in species composition and abundance can radically influence hydrological and atmospheric systems, plant and animal ranges, and human populations, making this challenge an important one to address. Forest ecologists have gathered a great deal of data over the past decades and are now using novel quantitative and computational tools to translate those data into predictions about the fate of forests. Here, after a brief review of the threats to forests over the next century, one of the more promising approaches to making ecological predictions is described: using hierarchical Bayesian methods to model forest demography and simulating future forests from those models. This approach captures complex processes, such as seed dispersal and mortality, and incorporates uncertainty due to unknown mechanisms, data problems, and parameter uncertainty. After describing the approach, an example by simulating drought for a southeastern forest is offered. Finally, there is a discussion of how this approach and others need to be cast within a framework of prediction that strives to answer the important questions posed to environmental scientists, but does so with a respect for the challenges inherent in predicting the future of a complex biological system.

As changes in climate become more apparent, ecologists face the challenge of predicting species responses to the new conditions. Most forecasts are based on climate envelopes (CE), correlative approaches that project future distributions on the basis of the current climate often assuming some dispersal lag. One major caveat with this approach is that it ignores the complexity of factors other than climate that contribute to a species' distributional range. To overcome this limitation and to complement predictions based on CE modeling we carried out a transplant experiment of resident and potential-migrant species. Tree seedlings of 18 species were planted side by side from 2001 to 2004 at several locations in the Southern Appalachians and in the North Carolina Piedmont (U.S.A.). Growing seedlings under a large array of environmental conditions, including those forecasted for the next decades, allowed us to model seedling survival as a function of variables characteristic of each site, and from here we were able to make predictions on future seedling recruitment. In general, almost all species showed decreased survival in plots and years with lower soil moisture, including both residents and potential migrants, and in both locations, the Southern Appalachians and the Piedmont. The detrimental effects that anticipated arid conditions could have on seedling recruitment contradict some of the projections made by CE modeling, where many of the species tested are expected to increase in abundance or to expand their ranges. These results point out the importance of evaluating the potential sources of migrant species when modeling vegetation response to climate change, and considering that species adapted to the new climate and the local conditions may not be available in the surrounding regions.