Article

Domination of hillslope denudation by tree uprooting in an old-growth forest

October 2016
Geomorphology 276

DOI:10.1016/j.geomorph.2016.10.006

Authors:

Jonathan Phillips

University of Kentucky

Pavel Samonil

The Silva Tarouca Research Institute

Łukasz Pawlik

University of Silesia in Katowice

Jan Trochta

Silva Tarouca Research Institute for Landscape and Horticulture

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Razula forest preserve in the Carpathian Mountains of the Czech Republic is an unmanaged forest that has not been logged or otherwise anthropically disturbed for at least 83 years, preceded by only infrequent selective logging. We examined this 25 ha area to determine the dominant geomorphological processes on the hillslope. Tree uprooting displaces about 2.9 m³ of soil and regolith per year, representing about 1.5 uprooted trees ha− 1 yr− 1, based on forest inventory records dating back to 1972, and contemporary measurements of displaced soil and pit-mound topography resulting from uprooting. Pits and mounds occupy > 14% of the ground surface. Despite typical slope gradients of 0.05 mm− 1, and up to 0.41, little evidence of mass wasting (e.g., slump or flow scars or deposits, colluvial deposits) was noted in the field, except in association with pit-mound pairs. Small avalanche and ravel features are common on the upslope side of uproot pits. Surface runoff features were rare and poorly connected, but do include stemwash erosion associated with stemflow. No rills or channels were found above the valley bottom area, and only small, localized areas of erosion and forest litter debris indicating overland flow. Where these features occurred, they either disappeared a short distance downslope (indicating infiltration), or indicate flow into tree throw pits. Surface erosion is also inhibited by surface armoring of coarse rock fragments associated with uprooting, as well as by the nearly complete vegetation and litter cover. These results show that the combination of direct and indirect impacts of tree uprooting can dominate slope processes in old-growth, unmanaged forests. The greater observed expression of different hillslope processes in adjacent managed forests (where tree uprooting dynamics are blocked by management activities) suggests that human interventions can change the slope process regime in forest ecosystems.

Root plates of uprooted trees − Automatic detection and biotransport estimation using LiDAR data and field mapping

Article

Full-text available

Jul 2024

Janusz Godziek

The availability of LiDAR data (including open-source data), combined with specialized algorithms, allows the use of these data to automatically detect landforms, vegetation and other objects. LiDAR point clouds have been frequently applied for the detection and evaluation of living trees but never for root plates of uprooted trees. However, tree uprooting is one of the most important biotic-abiotic interactions in temperate forests. This process leads to the formation of root plates, i.e., microrelief forms consisting of undecomposed tree root systems and the attached soil and rock particles. Root plates are involved in biotransport, i.e., the movement of soil and rock material by living organisms. The objective of this study was to develop an automatic method for root plate detection and volume (and thus biotransport) estimation based on LiDAR data. The study area included three Norway spruce-dominated plots located in two national parks in the Polish Carpathians. For validation, the author mapped the root plates using a GNSS receiver and measured their dimensions. We created the differential model presenting the height of root plates, fallen trunks, and dense understory vegetation by interpolating the last returns with a normalized height < 2 m. We automatically extracted the root plate locations and computed their volume using three ways of estimation. The method was built in R. Depending on the study plot, the root plate detection rates ranged from 70.3 % to 79.1 %. For different ways of estimation, the mean root plate volume varied in a range of 2.2-3.35 m³, while the mean biotransport reached 176.1-268.3 m³/ha. The method offers the best results for LiDAR data with a minimal density of 8 pts/m². We recommend using this method for 1) protected Norway spruce stands and 2) windthrows with no or few young conifers. The method can be applied to 1) assess the amount and spatial distribution of root plates and 2) determine the degree of soil disturbance and transport of soil material. Applying point cloud data to investigate the effects of tree uprooting can improve the understanding of the scale and course of different environmental processes related to this phenomenon. In future studies, field root plate measurements and volume estimations could be independently confirmed by using LiDAR data and the method presented in this study.

Soil erosion affected by trees in a tropical primary rain forest, Papua New Guinea

Article

Mar 2023
GEOMORPHOLOGY

Indirect biogeomorphic and soil evolutionary effects of spruce bark beetle

Article

Sep 2020
GLOBAL PLANET CHANGE

https://authors.elsevier.com/a/1blC23HcE1cwu3 Outbreaks of bark beetles, for example Ips typographus L. in Eurasia or Dendroctonus ponderosae Hopkins in North America, have serious impacts on forest resources, biodiversity, and ecological dynamics, with economical and social ramifications. Moreover, many models predict increasing frequency and severity of such biotic disturbances due to ongoing climate change, and land use driven changes in forest structure and composition. Bark beetles are recognized as keystone species due to their strong and complex effects on ecosystem dynamics. However, due to the increasingly widely recognized biogeomorphic impacts of trees, bark beetles may have significant indirect biogeomorphic and pedogenetic impacts through their effects at scales ranging from individual trees to forest landscapes. These include: (1) Reduced uprooting, with associated impacts on topography , mass movements, regolith and soil formation, and slope hydrology; (2) Reductions in bioprotection via trapping of downslope sediment movement; (3) Hydrological impacts, including increased total runoff and increased proportion of subsurface flow; (4) Decreased microtopographic irregularity (and associated hydrological and pedological impacts); and (5) Changes in biochemical and biomechanical effects on soils, regolith, and hillslope morphology. Five separator factors (discriminators between different developmental trajectories) were revealed for the case of the central European region. These factors may determine the occurrence and severity of biogeomorphic impacts: First is whether the site is prone to potential uprooting or whether an spruce bark beetle (SBB) outbreak is initiated by a blowdown/uprooting event. Second is whether the site is dominated by mineral soils or Histosols. A third discriminating factor is whether the forest is managed or unmanaged, which determines the pre-attack tree species composition and coarse woody debris and disturbance regimes; and a fourth is the post-outbreak management. Finally, the fifth separator factor relates to slope thresholds that determine the significance of impacts on mass movements and erosion. These findings support the need, and provide guidelines , for research on geomorphic impacts of bark beetle infestations. Though we mainly restrict our consideration to bark beetles in Europe, both our approach and findings are likely to have broader relevance for biogeomorphic impacts of extensive tree mortality.

Changes in the radial growth of trees in relation to biogeomorphic processes in an old‐growth forest on flysch, Czechia

Article

Jun 2020

Tree radial growth is influenced by individual tree abilities, climate, competition, disturbance regimes, as well as by biogeomorphic processes including biomechanical interactions between trees and soil. Trees are actively involved in hillslope dynamics, both responding to and affecting many (bio)geomorphic processes. Using dendrochronology we studied feedbacks associated with tree‐soil‐landscape formation, specifically relationships between hillslope processes, biomechanical effects of trees in soils, tree microhabitat conditions and their morphological adaptations, in the flysch zone of the Carpathians. We visually evaluated stem shape, microhabitat conditions, and the biomechanical effects of 1663 trees, Cores were taken in four growing directions from 224 individuals of European beech (Fagus sylvatica L.). In a set of 193 cross‐dated beeches, average tree‐ring widths and tree eccentricities in all directions were calculated and analysed in relation to the biogeomorphic impacts of trees. Some significant drivers of tree radial growth and sources of stem eccentricity were detected. The radial growth of trees on which deadwood was leaning was markedly limited. On the other hand, trees with exposed roots expressed the highest growth rates. This clearly suggests that root exposure may not be an effect of “exogenous” soil creep, but may rather result from individually intensifying tree growth due to fine‐scale disturbance dynamics. The response of biomechanical tree‐soil interactions in tree radial growth weakened with increasing stem diameter, reflecting the stabilizing role of larger trees. The significance of calendar year on radial growth suggests seasonality in the dynamic component of soil creep. Tree eccentricity was observed mainly in the downslope direction, which suggests a relatively complex effect of biomechanics on stem tilting.

Soil, regolith, and weathered rock: Theoretical concepts and evolution in old-growth temperate forests, Central Europe

Article

Jun 2020
GEODERMA

Evolution of weathering profiles (WP) is critical for landscape evolution, soil formation, biogeochemical cycles, and critical zone hydrology and ecology. Weathering profiles often include soil or solum (O, A, E, and B horizons), non-soil regolith (including soil C horizons, saprolite), and weathered rock. Development of these is a function of weathering at the bedrock weathering front to produce weathered rock; weathering at the boundary between regolith and weathered rock to produce saprolite, and pedogenesis to convert non-soil regolith to soil. Relative thicknesses of soil (Ts), non-soil regolith (Tr) and weathered rock (Tw) can provide insight into the relative rates of these processes at some sites with negligible surface removals or deposition. Scenarios of weathering profile development based on these are developed in current study. We investigated these with ground penetrating radar, electrical resistance tomography, and seismic profiling at three old growth forest sites in the Czech Republic, on gneiss, granite, and flysch bedrock. We found that the geophysical methods – which generated thousands of separate measurements of Ts, Tr, Tw – to produce good estimates. The weathered rock layer (sensu lato) was generally the thickest of the weathering profile layers. Mean soil thicknesses were about 0.64–0.75 m at the three sites, with typical maxima around 1.5 m. Non-soil regolith thicknesses averaged about 2.5 m on the gneiss site and 1.2–1.4 at the other sites. Weathered rock had a mean thickness of 7 m at the gneiss site (up to 10.3), 4.6 at the granite site, and 3.4 on flysch. Results indicate that weathering at the bedrock weathering front is more rapid than conversion of weathered rock to regolith, which is in turn more rapid than saprolite-to-soil conversion by pedogenesis on all three bedrock types. No evidence was found of steady-state soil, non-soil regolith, or weathered rock thicknesses or evolution toward steady-state. Steady-state would require that weathering rates at the bedrock and/or regolith weathering fronts decline to negligible rates as profiles thicken, but the relative thicknesses at our study sites do not indicate this is the case.

Indicators of wind-driven forest disturbances – pit–mound topography, its automatic detection and significance

Article

Feb 2023
CATENA

Pit-and-mound topography is a result of tree uprooting caused by hurricane-force wind events and hence can act as a bioindicator of forest disturbance. The occurrence and evolution of pit–mound topography can be analyzed using detailed elevation data, such as point clouds from Light Detection and Ranging (LiDAR) surveys. The objective of this study was to develop an automatic method of pit–mound topography detection. We propose the usage of closed contour lines to extract the locations of pits and mounds. We performed analyses in two study areas (Markowa and Stonów) located on the Babia Góra Massif (southern Poland). We computed the digital elevation model (DEM), extracted contour lines, calculated the length of each contour line and selected only closed contours belonging to a specified length interval. Then, we created polygons from the outermost closed contour lines. We classified polygons into “pits” and “mounds” by investigating the location of the highest and lowest altitudes within the polygon. We tested 27 variants of our method using different DEM spatial resolutions, contour intervals and contour length intervals. To estimate the accuracy of our method, we created a validation dataset by performing manual recognition of pit–mound pairs based on the topographic position index (TPI). One of the highest accuracies, obtained for the 1st variant of our method, reached 96.9 % for pits, 93.8 % for mounds and 90.6 % for pit–mound pairs in the Stonów area. In the Markowa area, this variant achieved an accuracy of 95.2 % for pits, 90.5 % for mounds and 85.7 % for pit–mound pairs. Our method can be used as an important step in analyses conducted in forest ecology, geomorphology or soil science. ------------------------------------------------------------------------------------------------------------------------------------------ 50 days' free access to the full text of the article (till January 02, 2023), on this link: https://authors.elsevier.com/c/1g4dI1Dk5AVS29

Topographic Roughness on Forested Hillslopes: A Theoretical Approach for Quantifying Hillslope Sediment Flux From Tree Throw

Article

Full-text available

Oct 2021
GEOPHYS RES LETT

Wind-driven tree throw is an observable and consequential process that suddenly moves soil downslope, inverts the soil column, and roughens the surface with pit-mound topography. Quantifying fluxes due to tree throw is complicated by its stochastic nature and estimation requires averaging over a large area or long time. Here, we develop a theory that leads to a dimensionless metric directly measurable from high resolution topographic data. The theory explains the flux and topographic roughness as a function of tree throw production and decay rate by creep-like processes. We then form a measurable dimensionless variable that is the ratio of fluxes due to tree throw versus creep-like processes. Applying the theory to hillslopes in Southern Indiana, we find that tree throw accounts for 11%–18% of the hillslope sediment flux. The theoretical and observational findings provide important constraints on quantifying Critical Zone function from topographic parameters such as roughness.

Topographic roughness on forested hillslopes: a theoretical approach for quantifying hillslope sediment flux from tree throw

Preprint

Full-text available

Jun 2021

The Devonian Landscape Factory: plant-sediment interactions in the Old Red Sandstone of Svalbard and the rise of vegetation as a biogeomorphic agent

Article

Mar 2021

The Devonian Period was a crucial interval in the evolution of plants. During its 60 myr duration, it witnessed the successive evolution of roots, wood, trees and forests, and many of the biogeomorphic phenomena that operate in modern terrestrial environments came online for the first time. The Old Red Sandstone (ORS) of Svalbard consists of a near-continuous Silurian to Late Devonian record of land plant-colonized sedimentary environments and provides a perfect natural laboratory to aid understanding of the facies signatures and evolution of these phenomena. Here we describe and illustrate a catalogue of ORS features that provide evidence for the stepwise appearance of novel plant-sediment interactions, including: preserved plant material and rooting structures, early large woody debris accumulations, cannel coal deposits, and the oldest known vegetation-induced sedimentary structures, in addition to vegetation-influenced motifs of elevated mudrock content and complex alluvial sand bodies. These characteristics are combined to reconstruct changes to non-marine environments in this Devonian ‘landscape factory’. In addition to tectonic and climate influences, plant evolution first served as a control on the construction of the sedimentary record during this period and has persisted as a fundamental influence on Earth surface processes and landforms ever since.

Biogeomorphological Domination of Forest Landscapes: An example from the Šumava Mountains, Czech Republic

Article

Mar 2021
GEOMORPHOLOGY

Biogeomorphological and ecological succession following a disturbance or the exposure of new ground often proceeds in stages, from domination by abiotic, geophysical factors through stages characterized by increasing effects of biota, biotic-abiotic feedbacks, and eventual domination by ecological processes. However, some studies in forest settings have found more varied development patterns, including persistence of states dominated by biogeomorphic feedbacks. In this study we investigated this phenomenon In Norway spruce (Picea abies (L.) Karst.) dominated forests on the main ridge of the Šumava Mountains in the Czech Republic along the German and Austrian borders. Throughout most of the Holocene, Picea has strongly influenced microtopography and soil/regolith characteristics so as to inhibit hydrological connectivity and development of surface drainage, and maintain hydromorphic soil conditions. These strongly historically and geographically contingent ecosystem engineering effects create and maintain habitat that favors spruce over other trees. These interactions have maintained a landscape dominated by biogeomorphic feedbacks.

Modeling soil and landscape evolution – the effect of rainfall and land-use change on soil and landscape patterns

Article

Full-text available

Aug 2020

Humans have substantially altered soil and landscape patterns and properties due to agricultural use, with severe impacts on biodiversity, carbon sequestration and food security. These impacts are difficult to quantify, because we lack data on long-term changes in soils in natural and agricultural settings and available simulation methods are not suitable for reliably predicting future development of soils under projected changes in climate and land management. To help overcome these challenges, we developed the HydroLorica soil–landscape evolution model that simulates soil development by explicitly modeling the spatial water balance as a driver of soil- and landscape-forming processes. We simulated 14 500 years of soil formation under natural conditions for three scenarios of different rainfall inputs. For each scenario we added a 500-year period of intensive agricultural land use, where we introduced tillage erosion and changed vegetation type. Our results show substantial differences between natural soil patterns under different rainfall input. With higher rainfall, soil patterns become more heterogeneous due to increased tree throw and water erosion. Agricultural patterns differ substantially from the natural patterns, with higher variation of soil properties over larger distances and larger correlations with terrain position. In the natural system, rainfall is the dominant factor influencing soil variation, while for agricultural soil patterns landform explains most of the variation simulated. The cultivation of soils thus changed the dominant factors and processes influencing soil formation and thereby also increased predictability of soil patterns. Our study highlights the potential of soil–landscape evolution modeling for simulating past and future developments of soil and landscape patterns. Our results confirm that humans have become the dominant soil-forming factor in agricultural landscapes.

Incorporation of spatial autocorrelation improves soil–landform modeling at A and B horizons

Article

Dec 2019
CATENA

Research has shown that the performance of soil–landform models would improve if the effects of spatial autocorrelation were properly accounted for; however, it remains elusive whether the level of improvement would be predictable, based on the degree of spatial autocorrelation in the model variables. We evaluated this problem using 11 soil variables acquired from the A and B horizons along a hillslope of Žofínský Prales in the Czech Republic. The results showed that, with no exception, there were increases in R² and decreases in the Akaike information criterion (AIC), residual autocorrelation, and root-mean-square errors (RMSEs), after incorporating the spatial filters extracted by spatial eigenvector mapping into non-spatial regression models. Furthermore, the improvement of the model was positively proportional to the degree of spatial autocorrelation, inherent in the soil variables. That is, there were strikingly linear and significant relationships, in which strongly autocorrelated soil variables (i.e., having a high Moran's I value) exhibited greater increases in R² and decreases in AIC, residual autocorrelation, and RMSEs than their more weakly autocorrelated counterparts. These findings indicate that the degree of spatial autocorrelation present in soil properties can serve as a direct indicator for how much the performance of a traditional non-spatial soil–landform model would be enhanced, by explicitly taking into consideration the presence of spatial autocorrelation. More generally, our results potentially imply that the need for and benefit from incorporating spatial effects in geopedological modeling proportionally increases as the soil property of interest is more spatially structured (i.e., landform variables alone cannot capture soil spatial variability).

Modelling soil and landscape evolution – the effect of rainfall and land use change on soil and landscape patterns

Preprint

Full-text available

Nov 2019

Abstract. Humans have substantially altered soil and landscape patterns and properties due to agricultural use, with severe impacts on biodiversity, carbon sequestration and food security. These impacts are difficult to quantify, because we lack data on long-term changes in soils in natural and agricultural settings and available simulation methods are not suitable to reliably predict future development of soils under projected changes in climate and land management. To help overcome these challenges, we developed the HydroLorica soil-landscape evolution model, that simulates soil development by explicitly modelling the spatial water balance as driver of soil and landscape forming processes. We simulated 14500 years of soil – formation under natural conditions for three scenarios of different rainfall inputs. For each scenario we added a 500-year period of intensive agricultural land use, where we introduced tillage erosion and changed vegetation type. Our results show substantial differences between natural soil patterns under different rainfall input. With higher rainfall, soil patterns become more heterogeneous due to increased tree throw and water erosion. Agricultural patterns differ substantially from the natural patterns, with higher variation of soil properties over larger distances and larger correlations with terrain position. In the natural system, rainfall is the dominant factor influencing soil variation, while for agricultural soil patterns landform explains most of the variation simulated. The cultivation of soils thus changed the dominant factors and processes influencing soil formation, and thereby also increased predictability of soil patterns. Our study highlights the potential of soil-landscape evolution modelling for simulating past and future developments of soil and landscape patterns. Our results confirm that humans have become the dominant soil forming factor in agricultural landscapes.

Biogeomorphic effects of woody vegetation on bedrock streams

Article

Full-text available

Jun 2019
PROG PHYS GEOG

Tasnuba Jerin

The dynamic interactions between fluvial processes and vegetation vary in different environments and are uncertain in bedrock settings. Bedrock streams are much less studied than alluvial in all aspects, and in many respects act in qualitatively different ways. This research seeks to fill this lacuna by studying bedrock streams from a biogeomorphic perspective. It aims to identify the impacts of woody vegetation that may be common to fluvial systems and rocky hillslopes in general, or that may be unique to bedrock channels. A review of the existing literature on biogeomorphology – mostly fluvial and rocky hillslope environments – was carried out, and field examples of biogeomorphic impacts (BGIs) associated with fluvial systems of various bedrock environments were then examined to complement the review. Results indicate that bedrock streams exhibit both shared and highly concentrated BGIs in relation to alluvial streams and rocky hillslopes. Bedrock streams display a bioprotective geomorphic form – root banks (when the root itself forms the stream bank) – which is distinctive, but not exclusive to this setting. On the other hand, shared biogeomorphic impacts with alluvial streams include sediment and wood trapping, and bar and island development and stabilization (i.e. bioconstruction/modification and protection). Shared impacts with rocky hillslopes also include bioprotection, as well as displacement of bedrock due to root and trunk growth, and bedrock mining caused by tree uprooting (i.e. bioweathering and erosion). Two BGI triangles were developed to graphically display these relationships. Finally, this paper concludes that bedrock streams exhibit some BGIs that also occur in either alluvial channels or on rocky hillslopes. Therefore, no BGIs were identified that are absolutely unique to bedrock fluvial environments.

Landform record

Chapter

Jan 2025

Piotr Migoń

Spatiotemporal reconstruction of anthropogenically accelerated soil creep: Bâlea glacial valley, Făgăraş Mountains, Romanian Carpathians

Article

Full-text available

Sep 2024
CATENA

Topographic Roughness as an Emergent Property of Geomorphic Processes and Events

Article

Full-text available

Sep 2024

Earth's terrestrial surfaces commonly exhibit topographic roughness at the scale of meters to tens of meters. In soil‐ and sediment‐mantled settings topographic roughness may be framed as a competition between roughening and smoothing processes. In many cases, roughening processes may be specific eco‐hydro‐geomorphic events like shrub deaths, tree uprooting, river avulsions, or impact craters. The smoothing processes are all geomorphic processes that operate at smaller scales and tend to drive a diffusive evolution of the surface. In this article, we present a generalized theory that explains topographic roughness as an emergent property of geomorphic systems (semi‐arid plains, forests, alluvial fans, heavily bombarded surfaces) that are periodically shocked by an addition of roughness which subsequently decays due to the action of all small scale, creep‐like processes. We demonstrate theory for the examples listed above, but also illustrate that there is a continuum of topographic forms that the roughening process may take on so that the theory is broadly applicable. Furthermore, we demonstrate how our theory applies to any geomorphic feature that can be described as a pit or mound, pit‐mound couplet, or mound‐pit‐mound complex.

Evaluation of the hillslope fine-scale morphology under forest cover with pit-mound topography -Integration of geomorphometry, geophysical methods, and soil features

Article

Full-text available

May 2024
GEOMORPHOLOGY

Forested hillslopes are zones of specific surface hydrology and geomorphic activity regimes. Their distinct properties , namely terrain microrelief (<10 m in diameter and height), are often a result of past disturbances that control forest stand conditions, soil formation processes, and superficial processes. A clear bioindicator of the past forest disturbance is pit-mound topography, which, however, is challenging to study because of its complexity and relatively small sizes of individual forms (usually <5 m in diameter). The present study analyzed the spatial representation, geomorphometric, and geophysical evaluation of the rare pit-mound topography in the Karkonosze Mountains National Park, SW Poland, Central Europe. For this task, two digital terrain models (DTMs) have been considered and were based on different quality point clouds collected during airborne and terrestrial laser scanning (ALS and TLS, respectively). The first data allowed the production of the DTM in 1 × 1 m spatial resolution, while the second data offered the DTM in 0.025 × 0.025 m resolution. Various geomorpho-metric derivatives (Terrain Ruggedness Index, Geomorphons, Topographic Wetness Index, Valley Depth, and Negative Openness) were applied and compared based on these models. In the further part of the study, we applied electrical resistivity tomography (ERT) and electromagnetic induction (EMI), assisted by shallow soil sampling and analyses to support the interpretation of geophysical models. Our TLS-based DTM offered higher-quality models and a better representation of pit-mound topography. The high-quality TLS-based DTM elevation model can support close-to-reality hydrological and geomorphic model-ing. The geophysical investigation allowed us to isolate a critical difference between treethrow pits and mounds better represented by ERT models than shallow EMI models. The differences were partly supported by soil properties , namely lower electrical resistivity in treethrow pits were related to higher moisture conditions, organic matter, organic carbon, and silt content in pits. As a general property, pit-mound topography resulting from tree uprooting adds to the complexity of forested hillslope hydrology and geomorphic activity. The surficial hetero-geneity in hillslope topography was also evident in soil properties with sharp changes in short distances between treethrow mounds and pits.

Accelerated soil nitrogen cycling in response to a whole ecosystem acid rain mitigation experiment

Article

Dec 2023
SOIL BIOL BIOCHEM

Weathering and soil production under trees growing on sandstones – The role of tree roots in soil formation

Article

Full-text available

Aug 2023
SCI TOTAL ENVIRON

Rock weathering drives both landform formation and soil production/evolution. The less studied biological component of weathering and soil production caused by tree root systems is the main focus of the present study. Weathering by trees, which likely has been important in soil formation since the first trees emerged in the middle and late Devonian, is accomplished through both physical and biological means, like acids excreted by plants and exudates from associated bacterial communities. However, these processes are relatively poorly known. We assessed the impact of tree roots and associated microbiota on the potential level of biological weathering. Three research plots were selected in two sandstone regions in Poland. Two plots were in the Stołowe Mountains (Złotno, Batorów), a tableland built of Cretaceous sandstones. The third plot (Żegiestów) was in the Sącz Beskidy Mountains, the Carpathians. Soil samples were taken from tree root zones of Norway spruces from predefined sampling positions. Soils from non-tree control positions were also sampled. Soil samples were a subject of laboratory analyses which included the content of Fe and Al (amorphous and labile forms), carbon (C), nitrogen (N), and soil pH. The microbial functional diversity of soil microorganisms was determined using the Biolog (EcoPlate) system. Rock fragments were collected for mineralogical and a subject of optical microscopy and cathodoluminescence analyses in order to examine their mineralogical composition. Significant differences (pHolm-corrected < 0.05) between sample locations were found mostly for the Żegiestów plot: Soils at control positions differed from the crack and bulk soil sample positions in terms of C, N, C/N, and pH. Tree roots were able to develop a great variety of sizes and forms by following the existing net of bedrock discontinuities and hillslope microrelief. They developed along the most accessible surfaces, and caused rockcliff retreat and scree slope formation. These two features can be considered as initial stages of soil production. Trees add to the complexity of the soil system and allow formation of rhizospheric soils, and horizons rich in organic matter which are zones of a high microbial activity. However, as our study shows, rock cracks with roots cannot be considered as zones of microbial weathering. In addition, C content and microbial activity decreases with depth but can stay on a high level along living and dead roots. When entering rock fractures, they change the intensity of biomechanical weathering and soil properties. The highest biological activity of microorganisms was found in the control samples. Overall, tree roots do change the pattern of soil formation and explain the existing pattern of soil chemical properties, microbial activity, and potentially biological weathering intensity, and the intensity of those processes in correlation with root presence varies in space.

Fire‐produced coarse woody debris and its role in sediment storage on hillslopes

Article

Mar 2023

Interactions between vegetation and sediment in post‐fire landscapes play a critical role in sediment connectivity. Prior research has focused on the effects of vegetation removal from hillslopes, but little attention has been paid to the effects of coarse woody debris (CWD) added to the forest floor following fires. We investigate the impacts of CWD on hillslope sediment storage in post‐fire environments. First, we present a new conceptual model, identifying “active” storage scenarios where sediment is trapped upslope of fire‐produced debris such as logs, and additional “passive” storage scenarios including the reduced effectiveness of tree‐throw due to burnt roots and snapped stems. Second, we use tilt table experiments to test controls on sediment storage capacity. Physical modeling suggests storage varies nonlinearly with log orientation and hillslope gradient, and the maximum storage capacity of log barriers in systems with high sediment fluxes likely exceeds estimates that assume simple sediment pile geometries. Last, we calculate hillslope sediment storage capacity in a burned catchment in southwest Montana by combining high‐resolution topographic data and digitization of over 5000 downed logs from aerial imagery. We estimate that from 3500–14 000 m ³ of sediment was potentially stored upslope of logs. These estimates assume that all downed logs store sediment, a process that is likely temporally dynamic as storage capacity evolves with CWD decay. Our results highlight the role that CWD plays in limiting rapid sediment movement in recently burned systems. Using a range of potential soil production rates (50–100 mm/ky), CWD would buffer the downslope transport of ~35–280 years of soil produced across the landscape, indicating that fire‐produced CWD may serve as an important source of sediment disconnectivity in catchments. These results suggest that disturbance events have previously unaccounted‐for mechanisms of increasing hillslope sediment storage that should be incorporated into models of sediment connectivity.

The current and future role of biota in soil-landscape evolution models

Article

Full-text available

Jan 2022
EARTH-SCI REV

Biota are major drivers of geomorphological development. Vegetation and soil fauna act as ecosystem engineers, changing the environment through physical structures and individual activities such as litter layering, tree uprooting, and animal mounding. Furthermore, through varying litter quality triggering different degrees of animal bioturbation, they jointly drive soil and landscape development heterogeneously in space over time. Soil-landscape evolution models succeed in incorporating soil development with landscape evolution. However, the roles of biota and biotic interactions in these models are still underexposed. We cannot fully understand changes in environmental and soil-landscape systems without a proper appreciation of biotic processes. In this contribution, we first review the role of biota in pedological and geomorphological processes. Then we compare the coverage of soil and landscape processes of soil-landscape evolution models and outline the role of biota in current soil-landscape evolution models. Finally, we define five levels of soil-landscape evolution model complexity that allow increased detail in biota-soil-landscape interactions. The results show how vegetation characteristics and animal bioturbation in current models are simplified compared with geomorphological processes, and that the geomorphological impact of litter quality and quantity and interactions between vegetation and animals are not taken into consideration at all. As understanding the complex soil-landscape-biota system is fundamental in exploring the coevolution of ecosystem and landscape, it deserves more efforts to develop a biota-soil-landscape evolution model that does more justice to the manifold impacts of biota.

Overbank silt-clay deposition and intensive Neolithic land use in a Central European catchment - Coupled or decoupled?

Article

Full-text available

Oct 2021

Hydro-sedimentary processes such as soil erosion, sediment transport, deposition, and re-deposition influence the environmental evolution of floodplains, especially in loess-covered catchments. Holocene floodplain deposits are thus a source of information on previous hydro-sedimentary dynamics and land use in the catchment. Resulting from forest clearings in the catchment, the onset of overbank silt-clay deposition is considered as an initial and significant human-induced process affecting Central European floodplain evolution and ecosystems. However, it is difficult to separate climate-related from anthropogenic forces on depositional environments, and the complexity of the hydro-sedimentary responses is part of an ongoing debate in geoscientific, ecological, and archaeological communities. This study focuses on the Central European Weiße Elster river system, where humans have been influencing hydro-sedimentary processes since the Early Neolithic due to land-use-induced soil erosion predominantly in the loess-covered sub-basin of the middle course. A catchment-scale XRF element record of fluvial sediment sources combined with the geochemical characterisation of Holocene floodplain deposits aim for a better understanding of the interplay between past soil erosion, overbank deposition in the floodplain, and potential changes in sediment provenances. The Weiße Elster floodplain chronosequences show a geochemical differentiation into a lower (Neolithic) and an upper (post-Neolithic) overbank silt-clay deposition. The construction of a sediment source fingerprinting mixing model yields the significant finding that the Neolithic overbank silt-clay deposition reveals a remote provenance signal from the upper catchment and less from the proximal loess-covered sub-catchment. According to a systematic archaeological data survey, the upper catchment was not permanently settled and used for agriculture in the Neolithic period. This contradicts the previous assumption that Neolithic overbank silt-clay deposition primarily originates from forest clearings and subsequent farming-induced soil erosion in the catchment. From a more general perspective, further examination of existing hypotheses concerning overbank silt-clay deposition in Central European floodplains is thus in order.

Vegetation and Geomorphic Connectivity in Mountain Fluvial Systems

Article

Full-text available

Feb 2021

Piotr Cienciala

Rivers are complex biophysical systems, constantly adjusting to a suite of changing governing conditions, including vegetation cover within their basins. This review seeks to: (i) highlight the crucial role that vegetation’s influence on the efficiency of clastic material fluxes (geomorphic connectivity) plays in defining mountain fluvial landscape’s behavior; and (ii) identify key challenges which hinder progress in the understanding of this subject. To this end, a selective literature review is carried out to illustrate the pervasiveness of the plants’ effects on geomorphic fluxes within channel networks (longitudinal connectivity), as well as between channels and the broader landscape (lateral connectivity). Taken together, the reviewed evidence lends support to the thesis that vegetation-connectivity linkages play a central role in regulating geomorphic behavior of mountain fluvial systems. The manuscript is concluded by a brief discussion of the need for the integration of mechanistic research into the local feedbacks between plants and sediment fluxes with basin-scale research that considers emergent phenomena.

Spatial dendrogeomorphic sampling based on the specific tree growth responses induced by the landslide mechanism

Article

Feb 2021
QUAT GEOCHRONOL

Karel Šilhán

The knowledge of spatial distribution of landslide events is crucial from forest management, landscape planning or hazard assessment point of view. Dendrogeomorphic approaches are actually a suitable tool for construction of past landslide behaviour due to known position of sampled trees. The position of trees on the landslide surface can influence the detection of the spatial patterns of landslide reactivation and considerably influence the amount and intensity of recorded landslide signals within tree ring series. This fact is caused by the presence of various morphological zones with different movement mechanisms that create landslide bodies. This study used tree ring data from 1030 tree ring series coming from 515 trees (Picea abies (L.) Karst.: 482; Larix decidua L.: 33) occupying ten different complex landslides in the Outer Western Carpathians to test the spatial distribution of landslide signals during reactivation events. Next, specific effects of six different landslide morphological zones on tree growth was studied to detect the most valuable sites for future sampling on landslide surfaces. The analysis of spatial patterns can be used as a rigorous indicator for landslide events in the case of a limited number of tree ring signals. Thus, the spatial patterns of landslide reactivations were tested using the Moran index. Moreover, this analysis is suitable only for block-type landslides (not for flow-like landslides). Next, this study presents a general model of the movement mechanism effect on tree growth in individual morphological zones creating complex landslide surfaces. Finally, based on the obtained results, recommendations for future sampling strategies regarding the position of trees within specific morphological zones are presented. Generally, trees on subhorizontal landslide blocks or in the zone of plastic shallow movement should be preferred in contrast to trees on the steep parts of landslides or in the source zone, which should be avoided.

Integrating connectivity theory within watershed modelling part I: Model formulation and investigating the timing of sediment connectivity

Article

Jun 2020
SCI TOTAL ENVIRON

Integrating connectivity theory within watershed modelling is one solution to overcome spatial and temporal shortcomings of sediment transport prediction, and Part I and II of these companion papers advance this overall goal. In Part I of these companion papers, we present the theoretical development of probability of connectivity formula considering connectivity's magnitude, extent, timing and continuity that can be applied to watershed modelling. Model inputs include a high resolution digital elevation model, hydrologic watershed variability, and field connectivity assessments. We use the model to investigate the dependence of the probability of connected timing and spatial connectivity on sediment transport predictors. Results show the spatial patterns of connectivity depend on both structural and functional characteristics of the catchment, such as hillslope gradient, upstream contributing area, soil texture, and stream network configuration (structural) and soil moisture content and runoff generation (functional). Spatial connectivity changes from catchment-to-catchment as a function of soil type and drainage area; and it varies from event-to-event as a function of runoff depth and soil moisture conditions. The most sensitive connected pathways provide the stencil for the probability of connectivity, and pathways connected from smaller hydrologic events are consistently reconnected and built upon during larger hydrologic events. Surprisingly, we find the probability of connected timing only depends on structural characteristics of catchments, which are considered static over the timescales analyzed herein. The timing of connectivity does not statistically depend on functional characteristics, which relaxes the parameterization across events of different magnitudes. This result occurs because the pathway stencil accumulates sediment from adjacent soils as flow intensity increases, but this does not statistically shift the frequency distribution.

Impact of trees and forests on the Devonian landscape and weathering processes with implications to the global Earth's system properties - A critical review

Article

Full-text available

May 2020
EARTH-SCI REV

Evolution of terrestrial plants, the first vascular plants, the first trees, and then whole forest ecosystems had far reaching consequences for Earth system dynamics. These innovations are considered important moments in the evolution of the atmosphere, biosphere, and oceans, even if the effects might have lagged by hundreds of thousands or millions of years. These fundamental changes in the Earth's history happened in the Paleozoic: from the Ordovician, the time of the first land plants, to the Carboniferous, dominated by forest ecosystems. The Devonian Plant Hypothesis (DPH) was the first concept to offer a full and logical explanation of the many environmental changes associated with the evolution of trees/forests that took place during this time period. The DPH highlighted the impact of deep-rooted vascular plants, particularly trees on weathering processes, pedogenesis, nutrient transport, CO2 cycling, organic and inorganic carbon deposition, and suggests further possible consequences on the marine realm (oceanic anoxia and extinction during the Late Devonian). Here we attempt to combine the DPH and the related expansion in biodiversity, the Devonian Plant Explosion (DePE), with the Biogeomorphic Ecosystem Engineering (BEE) concept. This idea connects tree growth and activity with initiation and/or alteration of geomorphic processes, and therefore the creation or deterioration of geomorphic landforms. We focus on trees and forest ecosystems, as the assumed dominant driver of plant-initiated change. We find that whereas there is a broad evidence of trees as important biogeomorphic ecosystem engineers, addressing the DPH is difficult due to limited, difficult to interpret, or controversial data. However, we argue the concept of BEE does shed new light on DPH and suggest new data sources that should be able to answer our main question: were Devonian trees Biogeomorphic Ecosystem engineers?

Volcanic ash driven regolith stripping in a semiarid forest in central Oregon

Preprint

Full-text available

Oct 2019

Deposits of hillslope colluvium can be used to reconstruct a landscape's eco-logic, geomorphic or pedogenic history. Herein, we focus on exploring the interaction between aeolian inputs (volcanic ash) and forest expansion as a novel driver of collu-viation and soil creep recorded in soil stratigraphic sections from a forest in central Oregon. Three toposequences spanning an orographic climate gradient were selected to investigate climatic modulation of colluviation processes following the deposition of volcanic ash due to the eruption of Mt. Mazama. The driest site, Deep Creek, is comprised of two toposequences and provides evidence that colluvium from ups-lope has been transported significantly farther downslope than the wetter site. The wetter site, Slide Mountain, has clearer and overall thicker stratigraphic packages than those found at Deep Creek, though they are spatially compressed, possibly indicating less effective colluvial transport. Regional paleoclimate reconstructions make transport mechanisms such as solifluction or gelifluction unlikely. As a result, the cobbly and stony colluviual sequences are inferred to have been generated due to * Corresponding author-Vance Almquist (almquist.vance@epa.gov) tree throw, indicating that forest expansion resulted in regolith stripping, thus confirming the plausibility of positive feedbacks in soil production. Furthermore that hillslope stripping appears to have emerged as a result of vegetation-soil coupling, as opposed to climatic drivers, has significant consequences for the interpretation of colluvial paleosols, especially in semiarid and arid settings.

Submitted to Catena

Preprint

Full-text available

Oct 2019

Weathering fronts

Article

Aug 2019
EARTH-SCI REV

A distinct boundary between unweathered and weathered rock that moves downward as weathering proceeds—the weathering front—is explicitly or implicitly part of landscape evolution concepts of etchplanation, triple planation, dynamic denudation, and weathering- and supply-limited landscapes. Weathering fronts also figure prominently in many models of soil, hillslope, and landscape evolution, and mass movements. Clear transitions from weathered to unweathered material, increasing alteration from underlying bedrock to the surface, and lateral continuity of weathering fronts are ideal or benchmark conditions. Weathered to unweathered transitions are often gradual, and weathering fronts may be geometrically complex. Some weathering profiles contain pockets of unweathered rock, and highly modified and unmodified parent material at similar depths in close proximity. They also reflect mass fluxes that are more varied than downward-percolating water and slope-parallel surface processes. Fluxes may also be upward, or lateral along lithological boundaries, structural features, and textural or weathering-related boundaries. Fluxes associated with roots, root channels, and faunal burrows may potentially occur in any direction. Just as pedology has broadened its traditional emphasis on top-down processes to incorporate various lateral fluxes, studies of weathering profiles are increasingly recognizing and incorporating multidirectional mass fluxes. Examples from karst systems may also be useful, where concepts of laterally continuous weathering fronts, rock-regolith boundaries, and water tables; and an assumption of dominantly diffuse downward percolation are generally inapplicable. We also question the idea of a single weathering front, and of a two-stage process of weathering rock to regolith, and transforming regolith to soil. In many cases there appears to be three stages involving conversion of bedrock to weathered rock, weathered rock to regolith, and regolith to soil.

Biogeomorphology: Past, present and future

Article

Jul 2019
GEOMORPHOLOGY

H.A. Viles

Since the 1970s there has been a considerable expansion in biogeomorphological research which considers the complex, two-way relationships between biological, ecological and geomorphological systems over a wide range of spatial and temporal scales. Advances have been made in theoretical, methodological, thematic and applied aspects of biogeomorphology. A review of key publications and symposia over the period illustrates growth in biogeomorphology with particular advances in quantitative understandings of biogeomorphic interactions, in interdisciplinary participation, and in theoretical framings. Theoretical advances have been influenced by the desire to answer four fundamental questions: How do ecological and geomorphological systems interact? Is there a geomorphological signature of life? How important is biodiversity to landscape evolution and vice versa? How have life and landscape co-evolved? A review of methodological advances in biogeomorphology confirms the continuing importance of field monitoring, and the increasingly tight collaboration between experimental and modelling-based research. Thematically, particularly strong progress has been made in disentangling the complex bidirectional biogeomorphic interactions in coastal sedimentary environments, and fluvial and riparian systems. It is increasingly obvious that variation in ecological traits leads to large differences in biogeomorphic impacts of different species in different circumstances. This poses challenges for applications of biogeomorphology to environmental management and conservation. Seven key topics emerge from this review and provide the basis for a biogeomorphological research agenda to usher in the next 50 yr of progress.

The role of topography, canopy gaps, and forest edges in the distribution of windthrow damage in the Western Tatra Mountains, Poland

Article

Full-text available

Jan 2019

Dariusz Strzyżowski

Geomorphic edge effects in response to abiotic and anthropogenic disturbances in forest ecosystems of the Gorce Mountains, Western Carpathians

Article

Feb 2019
CATENA

In the present paper we report on the only known example of a hummocky meadow in Poland. The area of the Hala Długa in the Gorce Mountains is a hotspot of complex geomorphic edge effects that have been widely studied in relation to human impacts and forest disturbances. Applying an interdisciplinary approach, we aimed to study the geomorphic activity in edge conditions between two contrasting ecosystems, a high-mountain meadow and a forest. Several methods were applied: geomorphic mapping, radiocarbon dating, soil analysis, geomorphometry, wood anatomy, and investigations of historical maps. These methods enabled us to reconstruct the history of the Hala Długa over the past ca 300 years, and to evaluate geomorphic activity and soil dynamics in this area. The treethrow pit-mound microtopography (hummocky meadow, Buckelwiese) of this area was formed under forest conditions, but due to long-term human impacts linked to sheep grazing and mowing, was preserved as a distinct topography for at least 100 years. While this topography was still clearly visible in the 1950s, when it was first reported, it is currently gradually disappearing under trees that have formed a belt around the study area. Soils of the study site were disturbed by tree uprooting, with many key features identified during the soil profile analysis: spots of coarse partly oriented sandstone fragments in pits, patches of organic matter in the metamorphic B horizon, and a large number of root remnants and pieces of charcoal in different parts of treethrow mounds and pits. We suggest a non-linear or even polygenetic soil evolution due to altered vegetation and disturbance regimes. The evaluation of wood remnants revealed that the majority of uprooted tree species were Picea abies (L.) H. Karst and Larix decidua Mill. We conclude that in the Gorce Mountains geomorphic edge effects can form hotspots of geomorphic activity driven by human impacts, natural disturbances, and the specific hydrological regime in the highest parts of the massif.

The disturbance regime of an Early Holocene swamp forest in the Czech Republic, as revealed by dendroecological, pollen and macrofossil data

Article

Jul 2018
PALAEOGEOGR PALAEOCL

A unique remnant of forest dating back to the period 9733–7897 yr BC and consisting of hundreds of tree bases was discovered in the Czech Republic. We aimed to reveal the complex disturbance history of this (sub)fossil forest using dendrochronology, and to describe its detailed plant species composition changes using palaeobotanical techniques. Analysing such Early Holocene forest dynamics should help us understand the ability of the forest community to actively adapt to climate change and generally to understand the role of dynamic instability in ecosystem evolution. We anatomically identified woody species in 488 samples, and determined the ages, growth suppressions, releases and fire scars in 116 well preserved tree ring series using a modern boundary line approach. This image of the forest structure and dynamics was supplemented with analyses of pollen spectra and plant macrofossils in excavated profiles. In order to achieve accurate dating, we dated 87 samples using ¹⁴C and synchronized tree ring series, and compared them with an existing Pinus sylvestris chronology. The developmental trajectory of the forest was unique, and did not match the general trend of postglacial pine growth in central Europe. Palaeobotanical proxies indicated that during the circa 2000 years the forest persisted, this Early-Holocene ecosystem passed through several phases, reflected in the species composition of the vegetation as well as in habitat conditions. Nevertheless, the dominance of pine and the complex fine-scale disturbance regime were relatively robust and did not change fundamentally. Low-severity fires and short-term changes in soil moisture regime were crucial disturbance agents in the ecosystem. Stand-replacing disturbances were not found up to the gradual collapse of the forest around 8300 yr BC, replaced by a swamp community. The disturbance regime was relatively stable, suggesting a mitigating effect of changing climate due to the predominance of pine in the forest.

Anthracological and morphological analysis of soils for the reconstruction of the forest ecosystem history (Meshchera Lowlands, Russia)

Article

Full-text available

Jun 2018
QUATERN INT

Pedoanthracological methods have never been used for studying natural and anthropogenic factors of ecosystem dynamics in the area of the Middle Russian Upland. The article presents results of the first study of soil charcoal stratigraphy, taxonomy, and radiocarbon dating combined with morphological analysis of soil profiles performed for sandy soil (Podzols and Arenosols) in the Meshchera Lowlands. Charcoal samples from different soil patterns and horizons were taken from 19 soil pits in four forest sites. The taxonomic identification of charcoals was performed for 24 soil samples; 12 charcoal samples were radiocarbon-dated. The following three patterns of ancient pedoturbations were studied in the soil profiles: arable layers, root channels, and pits formed after treefalls with uprooting. Results of soil charcoal analysis were compared with pollen and microscopic charcoal analysis of the cores taken in the surrounding peats. Pinus charcoals of various age prevailed in all charcoal samples. Charcoal of Betula and Sorbus also occurred. The oldest charcoal fragments were 2610 cal. BP. The remaining charcoal samples were mainly grouped into three clusters: about 2200, about 900–1000, and later 500 cal. BP. We assume that most charcoal samples were associated with burning and subsequent plowing which provided the upper layer of the soil (arable layers and sometimes root channels) with charcoal fragments. Charcoals were most abundant in the deepest pits formed after ancient treefalls. Periods of accumulation of charcoals in the peatlands and in the soil did not coincide for the last several millennia in the study region: intensive mixing of charcoals into the soil began after a decrease in the flow of charcoals into the peats. We associate this with the changing dynamics of landscapes under the influence of anthropogenic factors.

Studying Tropical Dry Forests Secondary Succession (2005–2021) Using Two Different LiDAR Systems

Article

Full-text available

Sep 2023

Chronosequence changes among Tropical Dry Forests (TDFs) are essential for understanding this unique ecosystem, which is characterized by its seasonality (wet and dry) and a high diversity of deciduous trees and shrubs. From 2005 to 2021, we used two different airborne LiDAR systems to quantify structural changes in the forest at Santa Rosa National Park. Line- and shape-based waveform metrics were used to record the overall changes in the TDF structure. Based on a 16-year growth analysis, notable variations in height-related profiles were observed, particularly for RH50, RH100, and waveform-produced canopy heights. The results showed that Cy and RG have increased since the forests have been growing, whereas Cx has decreased. The decrease in Cx is because ground returns are lower when the canopy density i and canopy height increase. A positive relationship was observed between Cy and CH, RG, and RH100, particularly for the wet season data collected in 2021. These findings provide important insights into the growth dynamics of TDFs in Santa Rosa National Park and could inform future conservation efforts.

Hillslope roughness reveals forest sensitivity to extreme winds

Article

Full-text available

Jan 2023

Windthrow, or the uprooting of trees by extreme wind gusts, is a natural forest disturbance that creates microhabitats, turns over soil, alters hydrology, and removes carbon from the above-ground carbon stock. Long recurrence intervals between extreme wind events, however, make direct observations of windthrow rare, challenging our understanding of this important disturbance process. To overcome this difficulty, we present an approach that uses the geomorphic record of hillslope topographic roughness as a proxy for the occurrence of windthrow. The approach produces a probability function of the number of annual windthrow events for a maximum wind speed, allowing us to explore how windthrow or tree strengths may change due to shifting wind climates. Slight changes to extreme wind speeds may drive comparatively large changes in windthrow production rates or force trees to respond and change the distribution. We also highlight that topographic roughness has the potential to serve as an important archive of extreme wind speeds.

Predicting post‐wildfire overland flow using remotely sensed indicators of forest productivity

Article

Nov 2022

Wildfire can induce an increase in infiltration excess overland flow, which varies from barely detectible to extreme. Soil properties are an important contributor to this variability. Several studies found that a landscape's aridity (the balance of energy and water) is strongly correlated with an increased quantity of post‐wildfire overland flow, with burnt forests of higher aridity producing higher peak flow compared to wetter forests. Related process‐based studies suggested that this relationship can be explained by an interaction between inherent soil macroporosity (varies inversely with aridity) and fire induced water repellency; soils of higher macro‐porosity maintain high infiltration rates despite fire‐enhanced water repellence. Although the observed post‐wildfire runoff/aridity relationship has proven useful in mapping hydrological risk, its transferability is potentially limited for areas where other soil formation factors have greater influence. Here we propose that measurements related to landscape productivity may provide a mappable landscape metric that is based on soil formation processes that influence post‐fire infiltration capacity and may provide a more robust and transferable proxy of fire induced hydrologic change. To test this hypothesis, post‐wildfire runoff data from three new experimental sites with a coastal climate influence were combined with previously published data collected inland across a gradient of aridity. The results showed that post‐wildfire runoff was better correlated with measures of productivity than with aridity, supporting the hypothesis. It is therefore proposed that long‐term average productivity may be a more robust and transferable proxy in estimating the magnitude of increase in overland flow after fire than aridity. This most likely results from a stronger causal link between productivity and soil macroporosity, though this was not measured in this study. As with aridity, this proxy is mappable at high resolution using climate and remotely sensed data, enabling the application of landscape productivity metrics when predicting post‐wildfire hydrologic risk. This article is protected by copyright. All rights reserved.

Differences of carbon and nitrogen stoichiometry between different habitats in two natural Korean pine forests in Northeast China’s mountainous areas

Article

Full-text available

May 2022

There is a strong link between vegetation and environmental factors. Therefore, to elucidate how the stoichiometric characteristics of plants respond to different habitats, we studied organic carbon (C) and total nitrogen (N) stoichiometry characteristics of plants in four different habitats of two different natural Korean pine forests. Three of the habitats (gaps, mounds, and pits) were formed via tree uprooting, whereas an undisturbed site (closed canopies) was used as a control. The followings were our main findings: (1) the organic carbon content of more than half of the 12 picked plants showed significant differences in different habitats. Most of the plants in pit-mound complexes exhibited lower organic carbon contents than plants in gaps and closed canopies; (2) there was no significant differences in the total nitrogen content in 13 of the 25 groups of plant samples; (3) interestingly, the C/N of the sample groups with significant differences in total nitrogen also showed significant differences; (4) there was no significant variations in the stoichiometric characteristics of plants that grew in gaps; however, the variations among plants that grew in pits and mounds were significant; (5) through redundancy analysis (RDA), we find that the main factors effecting the C and N stoichiometric characters of the plants were plants own regulation and the change of photosynthetically active radiation (PAR). In conclusion, the C and N stoichiometric characteristics of plants did not respond to gap formations, but they did strongly respond to pit-mound complex formations. Photosynthetically active radiation was the most important effective factor to plants in the four habitats.

An approach to evaluate the dominant river biogeomorphic succession phase at the reach-scale

Article

Jun 2022
CATENA

The Fluvial Biogeomorphic Succession phase model (FBS model) differentiates Geomorphic (G), Pioneer (P), Biogeomorphic (B) and Ecological (E) phases of hydro-geophysical-biological interactions in river systems. To date, quantitative applications of this model have been restricted to field surveys of vegetation composition analysis at the patch-scale. Here we develop a biogeomorphic landform mapping approach to determine the dominant biogeomorphic succession phase at the reach scale. We categorize river morphology into four biogeomorphic landform types (G-, P-, B- and E-landforms) that have particular geomorphic, substrate and vegetation cover characteristics. Ratios of these landforms are used to calculate the dominant succession phase in a given reach. A test of this method conducted for two contrasting anabranching reaches of the Upper Yellow River indicates that landform ratios provide an efficient and reliable approach to assess river biogeomorphic succession phase. The approach can be adapted to support systematic cross-scalar analyses across the range of river environments.

Tree Mortality may Drive Landscape Formation: Comparative Study from Ten Temperate Forests

Article

Full-text available

Mar 2022
ECOSYSTEMS

Tree mortality can fundamentally affect soils, which in turn shape forest regeneration and dynamics. Here, we quantify the dynamics of soil volumes associated with tree mortality, parsing effects by mode of tree death (broken vs uprooted) and species. The concept of ecosystem biogeomorphic succession was also tested. We used repeated tree censuses carried out in ten European and North American forests, differing in species composition, climate, and disturbance regimes. Development of more than 172,000 individual trees was recorded over periods of up to 48 years, during which more than one-third of the trees died. Biogeomorphic impact of deaths was modeled using allometry and field measurements. Tree uprooting-related soil volumes accounted annually for 0.01–13.5 m³ha⁻¹, reaching maximum values on sites with infrequent strong windstorms (European mountains). The redistribution of soils related to trees that died standing ranged annually between 0.17 and 20.7 m³ha⁻¹ and were highest in the presence of non-stand-replacing fire (Yosemite National Park, USA). Comparison of the results with known long-term erosion rates suggests that on certain sites over the last few millennia, tree uprooting may represent a significant driver of landscape erosion. Despite the key role of severe disturbances, the data showed potential for future increases in the intensity of biogeomorphic processes. The high biogeomorphic potential in some USA sites that has not yet been realized can be activated by external changes in the disturbance regime. Forests in Central Europe, on the other hand, are more sensitive to changes in biogeomorphic processes due to species turnover.

The role of pit-mound microrelief in the redistribution of rainwater in forest soils: a natural legacy facilitating groundwater recharge?

Article

Full-text available

Apr 2022
EUR J FOREST RES

In commercial forest plantations dominated by Norway spruce (Picea abies L. Karst), the typically densely rooted forest floor and a poor understory contribute to the formation of surface or shallow hypodermic runoff, which limits the redistribution of infiltrated water to deeper soil layers. Pit-mound microrelief is a natural legacy in forest soils that originate from historical tree uprootings. This paper analyses the hydrological processes associated within the pit-mound microrelief based on the monitoring of soil electrical resistance (Rx). In two forested slopes, paired-tube profile probes were used to monitor the dynamics of Rx along four transects through pit-mound pairs at different soil depths. Cross-corelation analysis was used to detect the time-lag responses of deeper soil layers as compared to surface horizons within 15 pre-selected precipitation periods per site. Unlike other microsites, the Rx of deeper soil layers at pit microsites were mostly correlated to the Rx of surface horizons with a time lag of 0–6 h, demonstrating a fast redistribution of infiltrated water throughout the soil profile. Our results indicate that the pit-mound microrelief on forested slopes can positively contribute to the retention and redistribution of infiltrated water to the subsoil, not only through direct infiltration from the soil surface but also likely by the disruption and redirection of shallow lateral flow. Thereby, the pit-mound microrelief may facilitate groundwater recharge similarly as the technical measures that are currently used in arid and semiarid regions.

Biogeomorphological evolution of rocky hillslopes driven by roots in campos rupestres, Brazil

Article

Full-text available

Oct 2021
GEOMORPHOLOGY

The campos rupestres (rocky grassland) comprise an old-growth seasonally dry herbaceous ecosystem on mountaintops in central and eastern Brazil and in disjoint areas with sparse shrubs with high plant diversity and endemism. This ecosystem consists of sharp-edged quartzite landforms and rocky hillslopes with boulders, blocks, and sparse soil cover. The slopes in these environments have traditionally been viewed as a product of mechanical rock breakdown controlled by structural and lithological features of rocky hillslopes. In addition to the lithological effects on slope evolution, plant cover plays a pivotal role in the geomorphological process. We explored process–form relationships between plant cover and quartzite rocky hillslopes of campos rupestres, considering the functioning of root traits of rock dwelling endemic species of Velloziaceae. Velloziaceae is an iconic plant family in campos rupestres, and several species colonize quartzite rock with different biogeomorphic effects at different scales. We present a conceptual model of the evolution of quartzite hillslopes based on the arenization process driven by roots expressing a specialized nutrient-acquisition strategy: vellozioid roots. Our results show that at the outcrop scale, roots respond to previous lithological characteristics such as joints and fractures that allow root establishment, followed by the release of large quantities of carboxylates that lead to rock dissolution. The microscopic pattern of bioweathering is associated with enlargement of the quartzite secondary porosity through the formation of root microcracks. Roots that are about 100 μm thick form root mats that surround the grains and produce inter-mineral and intra-mineral porosity systems facilitating percolation of water and organic solutes increasing the weathering. This results in arenization of quartzite by grain-by-grain dissolution and reduces the rock strength, which leads to the formation of quartzite hillslopes, driven by a nutrient-acquisition strategy of vellozioid roots. The described biogeomorphic process determines trajectories of the development of landforms through time, slope-sediment production, slope morphology by the production of boulders and block fields, and sand patches that are reworked by surface runoff along the slope. The hillslopes and landforms that develop in campos rupestres are therefore products of self-reinforcing processes involving nutrient acquisition from bedrock by plants and denudation processes. Also, these positive feedbacks characterize the Velloziaceae species as ecosystem engineers.

Selection and landscape evolution

Chapter

Jan 2021

Jonathan Phillips

Darwinian natural selection acting on individuals is one of only several types of selection influencing landscape evolution. Ecological filtering and abiotic selection (including the least action principle and preferential flows) apply. The overarching principle is one of efficiency selection, whereby more efficient, stable, and durable forms, structures, patterns, networks, and flux pathways are more likely to occur, grow, and persist than less efficient ones. Particularly important forms are gradient selection, favoring steeper and faster flow paths; resistance selection, whereby more resistant features are preferentially preserved; biogeochemical selection, which favors more rapid elemental cycling; network selection, which makes more efficient flux and interaction networks more likely; and thermodynamic selection, reflecting the advantages of energy use efficiency. Efficiency selection is highly local, however, one of several reasons that landscapes and environmental systems are not always inevitably becoming more efficient overall. A case study illustrating selection principles is given.

Quantifying the influence of rainfall, vegetation and animals on soil erosion and hillslope connectivity in the monsoonal tropics of northern Australia

Article

May 2021

Erosion of soil by water is facilitated by both diffusive and fluvial processes. Here we examine three different soil redistribution processes operating at very different spatial and temporal scales in the monsoonal tropics of northern Australia. The first process, rainsplash, operates across the entire catchment. This process, while subject to annual and seasonal variations in rainfall amount and intensity, can be considered a constant forcing and redistributes on average 9 t ha‐1 yr‐1 (range ‐0.9 to 19 t ha‐1 yr‐1). The second process, bioturbation, where in this study soil is disturbed by feral pigs (wild boar), occurs in selected areas throughout each year. Pigs exhume 3 to 36.0 t ha‐1 yr‐1 (average ~ 11 t ha‐1 yr‐1). The effect of this disturbance may last for many years afterwards. The third process is the disturbance of the soil surface by tree throw and creation of pit‐mound topography (also a form of bioturbation), together with the resultant placement of the tree superstructure (above ground biomass) on the ground, which may form debris dams. Tree throw at the scale examined here is likely to occur only once every 50‐100 years with the influence of this single event lasting for at least ten years post event. Tree throw in a single event exhumed ~5 t/ha (1.1 – 9.5 t/ha) of soil. In contrast to rainsplash, pig disturbance and tree throw events are largely point based phenomena. Field observation suggests that it takes many years for the disturbance from both pigs and tree throw to be removed. We find here that in terms of relative soil redistribution, rainsplash has the largest influence with any erosional disturbance by pigs and tree throw being within the variability of rainsplash. However, the disruption of surface flow by the pig digs and tree throw disrupt sedimentological and hydrological connectivity.

An integrated approach to landscape evolution

Chapter

Jan 2021

Jonathan Phillips

An approach to landscape and Earth surface system evolution is outlined based on the inseparability of landform, soil, and ecosystem development, versus the traditional semi-independent treatment of geomorphic, ecological, pedological, and hydrological phenomena. Key themes are the coevolution of biotic and abiotic components of the environment; selection whereby more efficient and/or durable structures, forms, and patterns are preferentially formed and preserved; and the interconnected role of laws, place factors, and history. Existing conceptual frameworks for evolution of geomorphic, soil, ecological, and hydrological systems are reviewed and contrasted with the integrated approach.

The role of tree uprooting in the transporting of sediment and mixing of soil in the Tatra Mountains

Article

Jan 2021

Dariusz Strzyżowski

Tree uprooting is an important process which leads to many geomorphic consequences. Some of the most important are the transport of sediment and mixing of soil. The aim of this article is to make a detailed examination of the magnitude of sediment transport caused by an extreme windthrow event in three severely affected catchments. Also, a comparison is made of the windthrow event with a mass movement event in the aspect of the magnitude of sediment transport and soil mixing. The study was conducted in three second- to third-order catchments in the Tatra Mountains, where a strong foehn wind event caused extensive windthrow in 2013, and a high-magnitude rainfall event triggered mass movements in 2007. The volume of sediment uplifted by the uprooting event was calculated based on the mapping of root plates using high-resolution (0.04 m) aerial images and measurements of root plate volumes conducted in the field. The volume of sediment transported by shallow landslides was determined based on a Digital Elevation Model (DEM, 1-m resolution). Windthrows affected 34%, 76%, and 94% of the area of the investigated catchments. Most of the trees had fallen downslope. The direction of treefall was influenced by the slope aspect and steepness. Root plates and pits covered 1.3%, 4.8%, and 5.4% of the area of the catchments. Sediment flux generated by the uprooting event, calculated for the entire area of each investigated catchment ranged from 8.1 × 10−4 to 9.9 × 10−3 m3 m−1 event−1. This was notably lower than the sediment flux generated by the mass movement event (also calculated for the entire area of each catchment), which was 1.8−6.1 × 10−2 m3 m−1 event−1. By contrast, uprooting affected a much larger area than the mass movement event, which underlines its significant role in the mixing of soil.

A seismic monitoring approach to detect and quantify river sediment mobilisation by steelhead redd‐building activity

Article

Full-text available

Jun 2020

The role of spawning salmonids in altering river bed morphology and sediment transport is significant yet poorly understood. This is due, in large part, to limitations in monitoring the redd‐building process in a continuous and spatially extended way. A complementary approach may be provided through the use of a small seismic sensor network analysing the ground motion signals generated by the agitation of sediment during the redd‐building process. We successfully tested the viability of this approach by detecting and locating artificially‐generated redd signals in a reach of the Mashel River, Washington State, USA. We then utilize records of 17 seismic stations, in which we automatically detected seismic events that were subsequently manually checked, yielding a catalogue of 45 potential redd‐building events. Such redd‐building events typically lasted between one and twenty minutes and were comprised of a series of clusters of 50‐100 short energetic pulses in the 20‐60 Hz frequency range. The majority (> 90 %) of these redd‐building events occurred within eleven days, predominantly during the early morning and late afternoon. The seismically derived locations of the signals were in agreement with independently mapped redds. Improved network geometry and installation conditions are required for more efficient detection, robust location and improved energetic insights to redd‐building processes in larger reaches. The passive and continuous nature of the seismic approach in detecting redds and describing fish behaviour provides a novel tool for fish biologists and fisheries managers, but also for fluvial geomorphologists, interested in quantifying the amount of sediment mobilised by this ecosystem engineer. When complemented with classic approaches, it could allow for a more holistic picture of the kinetics and temporal patterns (at scales from seconds to multiple seasons) of a key phase of salmonid life cycles.

Co-evolution of soils and landscapes in the Anthropocene - from natural to intensively managed landscapes

Thesis

Full-text available

Nov 2020

Marijn van der Meij

Soils provide numerous functions to support natural and human life. Soils and their functions develop over long timescales (decennia to millennia) under influence of environmental properties and drivers such as water flow, vegetation type and topography of the landscape. At the same time, these environmental properties develop too, often under influence of soil properties and processes. This interactive co-evolution of soils and the landscape forms a complex system that can aggravate, or diminish, rates and direction of soil-landscape evolution. In the Anthropocene, a proposed geological Epoch where humans are the main forcing actors, soil-landscape evolution changed substantially under influence of anthropogenic processes, such as deforestation and tillage. In current intensively managed agricultural landscapes in undulating settings, rates of anthropogenic erosion far exceed rates of natural soil development, leading to severe soil and land degradation. Sustainable nature-based land management is crucial to counteract this degradation, and to preserve and restore soil functions for the environment and future generations. The aim of my thesis is to identify and quantify how soils and landscape have evolved and possibly co-evolved during the transition from natural land cover to intensive land management in the Anthropocene. The first part of this thesis (Chapter 2-3) aims at reconstructing the impact and rates of anthropogenic landscape change on complex agricultural fields. As study site I use the landscape laboratory CarboZALF D. CarboZALF D is a kettle-hole catchment of 4 ha with elevation differences up to 8 meters, located in north-eastern Germany. The catchment is characterized by complex small-scale topography, heterogeneities in the hydrological system and a long history of agricultural use. The colluvium in the closed kettle hole catchment provides a complete geo-archive of landscape change. In Chapter 2 we reconstruct the paleosurface of study site Carbo-ZALF-D prior to the anthropogenic erosion. We used an extensive dataset of soil descriptions, which enabled a detailed spatial estimate of erosion and deposition by estimating erosion based on soil profile truncations and deposition based on colluvium thickness. The paleosurface shows a high variation in topographic properties and suggests that natural soils and landscapes contain considerable spatial heterogeneity. In Chapter 3 we reconstruct the rates of deposition in Carbo-ZALF-D using Optically Stimulated Luminescence (OSL) dating. We present a novel methodology to apply OSL dating in colluvial sediments, where the soil chronology gets disturbed by reworking by ploughing after deposition. Our results show a 100-fold increase in deposition rates, starting around 5000 years ago. This increase does not solely represent increased erosion in the catchment, but is also caused by indirect effects of agricultural drainage. The kettle hole shows a complex spatiotemporal pattern of colluvial infilling and landscape evolution, which we were only able to reconstruct using a high OSL sampling density and extensive soil geomorphic research. The second part of this thesis aims at simulating the evolution of soils and landscapes under varying climatic and anthropogenic forcing. In Chapter 4 we review the role of water as dominant driver in natural soil and landscape evolution and its potential as driver in simulations with soil-landscape evolution models (SLEMs). Water plays a pivotal role in soil and landscape evolution, by transporting and transforming soil material and facilitating vegetation growth. In turn, surface and subsurface flow paths of water are controlled by soil and landscape properties. The co-evolution of soils, topography and the hydrological system is essential for understanding the response of soils and landscapes to changes in climate. However, this co-evolution can currently not be simulated over long timescales with SLEMs due to several conceptual and methodological challenges. We provide partial solutions for these challenges. In Chapter 5 we utilize these partial solutions to develop our SLEM HydroLorica. HydroLorica simulates soil and landscape evolution with various dynamic drivers such as water flow, vegetation type and land use. We included additional essential processes such as tree throw, soil creep and tillage. We use HydroLorica to simulate the evolution of soils and landscape under various rainfall and land-use scenarios for an artificial undulating landscape. The results show that in natural systems, rainfall amount is the dominant factor controlling soil and landscape heterogeneity, while for agricultural systems landform explains most of the variation. The cultivation of natural landscapes increases soil heterogeneity, but also increases correlations between soil and terrain properties. Our results confirm that humans have become the dominant soil forming factor in intensively managed landscapes. In the third part of this thesis (Chapter 6), I synthesize the findings from the research chapters to meet the objectives of this thesis. I critically evaluate the developed reconstruction methods in Chapters 2 and 3 and compare them with other potential methods. The development of HydroLorica in Chapters 4 and 5, with water flow as explicit driver and with increased process coverage, is a big step forward in soil-landscape evolution modelling. A combination of reconstruction and simulation methods is essential for developing and testing hypotheses of soil-landscape co-evolution. Soil-landscape evolution in natural and intensively managed landscapes have different characteristics due to different driving forces and dominant processes. In natural landscapes, soils develop to patterns where individual soils might be disturbed occasionally, but where the average properties are stable. In intensively managed landscapes, disturbance rates are much higher than in natural settings. As a consequence, slowly developing soil properties degrade, while fast-developing soil properties can form a new equilibrium. The co-evolution of soils and landscapes that occurs in natural settings is often controlled by biotic processes. In agricultural settings, humans control vegetation type and aggravate erosion processes through tillage. As a consequence, co-evolution does not occur in the sense that it does in natural settings, because interactions between landscape components are missing. However, the management of soils and landscapes is often adapted to counteract unintended changes to soils and landscapes under earlier management. In intensively managed landscapes, land management may thus co-evolve with the rest of the landscape.

A regime shift in sediment export from a coastal watershed during a record wet winter, California: Implications for landscape response to hydroclimatic extremes: Sediment flux regime shift

Article

May 2018

Small, steep watersheds are prolific sediment sources from which sediment flux is highly sensitive to climatic changes. Storm intensity and frequency are widely expected to increase during the 21st century, and so assessing the response of small, steep watersheds to extreme rainfall is essential to understanding landscape response to climate change. During record winter rainfall in 2016–17, the San Lorenzo River, coastal California, had nine flow peaks representing 2‐ to 10‐year flood magnitudes. By the third flood, fluvial suspended sediment showed a regime shift to greater and coarser sediment supply, coincident with numerous landslides in the watershed. Even with no singular catastrophic flood, these flows exported more than half as much sediment as had a 100‐year flood 35 years earlier, substantially enlarging the nearshore delta. Annual sediment load in 2017 was an order of magnitude greater than during an average‐rainfall year, and 500‐fold greater than in a recent drought. These anomalous sediment inputs are critical to the coastal littoral system, delivering enough sediment, sometimes over only a few days, to maintain beaches for several years. Future projections of megadroughts punctuated by major atmospheric‐river storm activity suggest that interannual sediment‐yield variations will become more extreme than today in the western U.S., with potential consequences for coastal management, ecosystems, and water‐storage capacity. The occurrence of two years with major sediment export over the past 35 years that were not associated with extremes of the El Niño Southern Oscillation or Pacific Decadal Oscillation suggests caution in interpreting climatic signals from marine sedimentary deposits derived from small, steep, coastal watersheds, to avoid misinterpreting the frequencies of those cycles.

Disturbances can control fine-scale pedodiversity in old-growth forests: is the soil evolution theory disturbed as well?

Article

Full-text available

Oct 2014

Biota–soil interactions in natural ecosystems are the subject of considerable research. Our hypothesis is that individual trees play a significant role through biomechanical and biochemical disturbances affecting soil formation in temperate forests, resulting in a complex spatial pattern of disturbance regimes and a close relationship between disturbance histories and soil units. In Žofínský Prales (Czech Republic) – the fourth oldest, continuously protected reserve in Europe and the first site of global research network SIGEO (Smithsonian Institution Global Earth Observatories) in continental Europe – we compared extensive dendrochronological, soil and pit–mound microtopography data both temporally and spatially from an area of anthropogenically unaffected 42 ha collected from 2008–2012. These data sets differ in terms of information complexity and length of memory: tree cores contain complex information about the disturbance history of the past 350 years, footprints of disturbances from the uprooting of a specific tree can persist 1700 years, and soils represent an extensive composite phenotype that has been developing for at least the entire postglacial period (10 500 years). On average, 6.18–13.41% of the canopy on individual soil units was disturbed per decade. Even though the "backbone" of key events in the development of the forest ecosystem remained the same (e.g. the 1870s, 1880s and 1980s), the internal structure of disturbance history often differed among soil units; the most exceptional were Gleysols and Histosols, where important feedback from soil to trees was expected. However, the characteristics of treethrow dynamics as well as the frequencies of stronger releases in core series also significantly differed along a gradient of terrestrial soil weathering and leaching (Haplic Cambisols – Dystric Cambisols – Entic Podzols – Albic Podzols). These results suggest the existence of several disturbance regimes within the forest, controlling fine-scale pedodiversity.

Conditions for feedbacks between geomorphic and vegetation dynamics on lateral moraine slopes: A biogeomorphic feedback window

Article

Full-text available

Oct 2015

Little Ice Age lateral moraines represent one of the most important sediment storages and dynamic areas in glacier forelands. Following glacier retreat, simultaneous paraglacial adjustment and vegetation succession affect the moraine slopes. Geomorphic processes (e.g., debris flows, interrill erosion, gullying, solifluction) disturb and limit vegetation development, while increasing vegetation cover decreases geomorphic activity. Thus, feedbacks between geomorphic and vegetation dynamics strongly control moraine slope development. However, the conditions under which these biogeomorphic feedbacks can occur are insufficiently understood and major knowledge gaps remain. This study determines feedback conditions through the analysis of geomorphic and vegetation data from permanent plots in the Turtmann glacier foreland, Switzerland. Results from multivariate statistical analysis (i) confirm that Dryas octopetala L. is an alpine ecosystem engineer species which influences geomorphic processes on lateral moraines and thereby controls ecosystem structure and function, and (ii) demonstrate that biogeomorphic feedbacks can occur once geomorphic activity sufficiently decreases for D. octopetala to establish and cross a cover threshold. In the subsequent ecosystem engineering process, the dominant geomorphic processes change from flow and slide to bound solifluction. Increasing slope stabilization induces a decline in biogeomorphic feedbacks and the suppression of D. octopetala by shrubs. We conceptualize this relationship between process magnitude, frequency and species resilience and resistance to disturbances in a ‘biogeomorphic feedback window’ concept. Our approach enhances the understanding of feedbacks between geomorphic and alpine vegetation dynamics on lateral moraine slopes and highlights the importance of integrating geomorphic and ecological approaches for biogeomorphic research.

Landslide phases in the Polish Outer Carpathians and their relation to climatic changes in the Late Glacial and the Holocene

Article

Full-text available

Jan 1998

Włodzimierz Margielewski

Supplementation of inventory of dated Carpathians landslides with new radiocarbon dated, allowed to author to interpretate landslide phases in the Carpathians. The basis for interpretation was correlation of periods of dated landslides concentration with the phases of Upper Vistula River activity, and the landslide phases (40 forms have been radiocarbonically dated till now) exactly correspond to the landslide phases earlier distinguished in the Carpathians. This concentration of dating in the following time intervals: the Late Glacial - Preboreal, 8.5-7.7 ka BP, 5.1-4.8 ka BP, 3.3-2.9 ka BP, 2.35-1.9 ka BP, 13th-15th Centuries and the Little Ice Age, also very well correlate to the phases of intensive fluvial activity of the Upper Vistula. Some concentrations of landslide radiocarbon datings do not agree with landslide phases, presently distinguished in the Carpathians. However, these periods: 4.2-3.9 ka BP, 2.6-2.7 ka BP, about 1.5 ka BP and 1.2-1.0 ka BP well correlate with distinguished at that time phases of intense activity of the Upper Vistula River. Three dated landslides mark the poorly documented phase of time range at 7.3-7.1 ka BP, which is not reflected in the fluvial activity of the Upper Vistula. The mentioned phase of time-range correlated with the climate changes of global range (glacial advances, fluctuation of lakes water level in Europe) and with local signs of activity of the Carpathian rivers and slopes. Due to relatively small number of radiocarbon datings, these periods delimited by the range of landslide radiocarbon datings, might be considered as landslide phases sensu lato.

The Razula virgin forest after 23 years (1972-1995)

Article

Full-text available

Jan 2001

Contemporary geomorphic processes in the Polish Carpathians under changing human impact

Article

Full-text available

Mar 2014
EPISODES

The paper presents activity of contemporary geomorphic processes in the Polish Carpathians, taking into account human impact on relief transformation in the past several centuries. Landsliding in the flysch Carpathians is a principal process in slope transformation, posing the most serious threat to man, both in the mountains and the foothills. On the other hand, unsuitable housing on slopes initiates mass movements, frequently with catastrophic consequences. Land use changes, in particular deforestation, have over the past 200 years fostered intensive slopewash and linear erosion, with this playing an important role in shaping foothill relief. Following changes in land use and channel regulation initiated at the beginning of the 20th century, a tendency to river bed deepening prevails. Moreover, floods, and not only extreme instances, continue to pose a threat to man, with their effects enhanced by housing in floodplain areas. A tendency consisting in the reduction of arable land and an increase in grassland and forest area, observed over the past two decades, will lead to a gradual limitation of slope-wash and wind erosion as well as a simultaneous increase in linear erosion on slopes and river bed deepening.

The Whitebox Geospatial Analysis Tools project and open-access GIS

Conference Paper

Full-text available

Apr 2014

John B Lindsay

Disturbances can control fine-scale pedodiversity in old-growth forests: is the soil evolution theory disturbed as well?

Article

Full-text available

Oct 2014
BG

Evidence for nonlinear, diffusive sediment transport on hillslopes and implications for landscape morphology

Article

Full-text available

Mar 1999

Steep, soil-mantled hillslopes evolve through the downslope movement of soil, driven largely by slope-dependent transport processes. Most landscape evolution models represent hillslope transport by linear diffusion, in which rates of sediment transport are proportional to slope, such that equilibrium hillslopes should have constant curvature between divides and channels. On many soil-mantled hillslopes, however, curvature appears to vary systematically, such that slopes are typically convex near the divide and become increasingly planar downslope. This suggests that linear diffusion is not an adequate model to describe the entire morphology of soil-mantled hillslopes. Here we show that the interaction between local disturbances (such as rainsplash and biogenic activity) and frictional and gravitational forces results in a diffusive transport law that depends nonlinearly on hillslope gradient. Our proposed transport law (1) approximates linear diffusion at low gradients and (2) indicates that sediment flux increases rapidly as gradient approaches a critical value. We calibrated and tested this transport law using high-resolution topographic data from the Oregon Coast Range. These data, obtained by airborne laser altimetry, allow us to characterize hillslope morphology at ≈2 m scale. At five small basins in our study area, hillslope curvature approaches zero with increasing gradient, consistent with our proposed nonlinear diffusive transport law. Hillslope gradients tend to cluster near values for which sediment flux increases rapidly with slope, such that large changes in erosion rate will correspond to small changes in gradien. Therefore average hillslope gradient is unlikely to be a reliable indicator of rates of tectonic forcing or baselevel lowering. Where hillslope erosion is dominated by nonlinear diffusion, rates of tectonic forcing will be more reliably reflected in hillslope curvature near the divide rather than average hillslope gradient.

Interaction between tree species populations and windthrow dynamics in natural beech-dominated forest, Czech Republic

Article

Full-text available

Sep 2012
FOREST ECOL MANAG

Interactions between pit-mound dynamics and tree species populations were studied in a natural mountain (fir)-spruce-beech forest. Pit-mounds are special habitats with unique erosion-sedimentation and microclimatic conditions, which continually influence the trees growing there. Our assumption was that these factors would impact on the competitive potential of the trees and that the interaction between the pit-mound dynamics and the tree layer would not be static, but would change depending on the ages of both the trees and the pit-mounds.

Geomorphometry and Spatial Hydrologic Modelling

Chapter

Full-text available

Jan 2009

Scott Dale Peckham

Bedrock erosion by root fracture and tree throw: A coupled biogeomorphic model to explore the humped soil production function and the persistence of hillslope soils

Article

Full-text available

Oct 2010

In 1877, G. K. Gilbert reasoned that bedrock erosion is maximized under an intermediate soil thickness and declines as soils become thinner or thicker. Subsequent analyses of this “humped” functional relationship proposed that thin soils are unstable and that perturbations in soil thickness would lead to runaway thinning or thickening of the soil. To explore this issue, we developed a numerical model that simulates the physical weathering of bedrock by root fracture and tree throw. The coupled biogeomorphic model combines data on conifer population dynamics, rootwad volumes, tree throw frequency, and soil creep from the Pacific Northwest (USA). Although not hardwired into the model, a humped relationship emerges between bedrock erosion and soil thickness. The magnitudes of the predicted bedrock erosion rates and their functional dependency on soil thickness are consistent with independent field measurements from a coniferous landscape in the region. Imposed perturbations of soil erosion during model runs demonstrate that where bedrock weathering is episodic and localized, hillslope soils do not exhibit runaway thinning or thickening. The pit-and-mound topography created by tree throw produces an uneven distribution of soil thicknesses across a hillslope; thus, although episodes of increased erosion can lead to temporary soil thinning and even the exposure of bedrock patches, local areas of thick soils remain. These soil patches provide habitat for trees and serve as nucleation points for renewed bedrock erosion and soil production. Model results also suggest that where tree throw is a dominant weathering process, the initial mantling of bedrock is not only a vertical process but also a lateral process: soil mounds created by tree throw flatten over time, spreading soil over bedrock surfaces.

Surface processes and interactions with forest vegetation on a steep mudstone slope, Stołowe Mountains, SW Poland

Article

Full-text available

Oct 2013
CATENA

The role of downpours in transformation of slopes in the Polish Carpathian Foothills

Article

Jan 2011

Małgorzata Kijowska-Strugała

Landslide hazard in the Polish flysch Carpathians

Article

Jan 2007

W. Raczkowski

World Reference Base for Soil Resources: A Framework for International Classification, Correlation and Communication: World Soil Resources Reports. 103

Book

Jan 2006

Soil deepening by trees and the effects of parent material

Article

Jul 2016
GEOMORPHOLOGY

Whitebox GAT: A case study in geomorphometric analysis

Article

Jul 2016
COMPUT GEOSCI-UK

John B Lindsay

This paper describes an open-source geographical information system (GIS) called Whitebox Geospatial Analysis Tools (Whitebox GAT). Whitebox GAT was designed to provide a platform for the rapid development and testing of experimental geospatial analysis methods, supported by its extensible design, integrated facilities for custom plug-in tool authoring, and its novel open-access design philosophy. One of the unique characteristics of Whitebox GAT is the ease with which users can inspect and modify the algorithms for individual geoprocessing tools. The open-access software model that Whitebox GAT adopts is designed to lessen the barriers that are often imposed on end-users when attempting to gain deeper understanding of how a specific function operates. While Whitebox GAT has an extensive range of GIS and remote sensing analytical capabilities, making it broadly suited for advanced scientific research applications in the Earth Sciences, this paper focusses on the software's application in the field of geomorphometry. An airborne LiDAR data set for a small headwater catchment of the Missisquoi River in northern Vermont, USA, was filtered to identify ground-points and then interpolated into a 2.0 m resolution bare-Earth DEM. The DEM was processed to remove spurious off-ground objects (mainly buildings), to reduce surface roughness under heavy forest cover, and to hydrologically pre-condition the DEM. These data were then used to extract salient hydrological structures, i.e. the stream network and their associated sub-basins.

Roots, Rock, and Regolith: Biomechanical and Biochemical Weathering by Trees and its Impact on Hillslopes - A Critical Literature Review

Article

Jun 2016
EARTH-SCI REV

The role of trees and forests as a critical component of the biosphere and critical zone, and of the Earth system more generally, is widely appreciated. Less known and acknowledged are the geomorphological functions of tree roots, though their importance has been widely referred to in soil studies, paleopedology and palaeobotany. Tree roots and their impact on weathering processes and soil production were incorporated in the Devonian plant hypothesis and tree root casts served as a key evidence of recognition of past soils in geology, sedimentology and palaeopedology. However, knowledge of biomechanical and biochemical weathering induced by vascular plant roots (mainly trees) has been rarely utilized in geomorphic studies. Biogeomorphic and pedologic studies in recent decades have highlighted the importance of tree uprooting, in which roots play a primary role, in soil development, regolith disturbance and bedrock mining. Other important functions of roots were also recognized, e.g.: soil displacement by growing roots, infilling of stump holes and root cavities, root groove development, direct and indirect effects taking place in the rhizosphere and mycorrhizosphere (mainly biochemical weathering of minerals, support by microbial communities and symbiotic fungi), and changes in porosity, permeability and hydrology of soils in the root zone. However, further studies are urgently needed because many aspects of biochemical and biomechanical weathering are not well understood. This is especially true with respect to taxa-specific impacts. Variations in root architectures, edaphic settings, ecological relationships, and geographic ranges result in substantially different biogeomorphic impacts of different tree species. Additionally, the same species in different environmental settings may have different effects.

Age and Reactivations of Catastrophic Complex Flow-Like Landslides in the Flysch Carpathians (Czech Republic/Slovakia)

Chapter

Apr 2014

Catastrophic complex flow-like landslides (CFLLs) are characterised by a deep-seated retrogressive landslide of structurally unfavourably oriented rocks and earthflows that occupy the lower slope positions and originate due to the liquefaction of material accumulated on the upper slopes. These landslides are locally important geomorphic agents of Late Quaternary mountain evolution in the Flysch Belt of the Outer Western Carpathians (Czech Republic/Slovakia). Most of the CFLLs dammed and steepened adjacent valleys. Radiocarbon dating suggests that a majority of them moved repeatedly throughout the Holocene, namely approx. every 1–2 ka. Dated events occurred during humid phases of the Younger Dryas/Holocene transition (11.5–9.4 cal ka BP), Atlantic chronozone (7.4–6.6 cal ka BP), the beginning of the Subboreal chronozone (ca. 4.6 cal ka BP) and, primarily, within the Subatlantic chronozone at ca. 2–0.8 cal ka BP (>50 % of all events). Our study suggests that slopes based on an unfavourable structural setting and affected by long-term deep-seated gravitational deformations may produce CFLLs, even if they are located in medium-high mountains. Although our chronological dataset is influenced by the erosion of older landforms, most of the dated reactivations correlate with regional increase in precipitation identified by previous palaeoenvironmetal studies.

Rapid mass wasting over the last 500 years in the High Tatra Mountains

Article

Jan 1995

A. Kotarba

The principal agent of sediment reworking on debris slopes in the High Tatra Mountains, located above the upper timber-line, is debris flow activity. Lake Zielony Staw Gasienicowy and Morskie Oko Lake are situated directly adjacent to these slopes and minerogenic sediment inwash due to rapid mass wasting produced distinct layers or laminae within gyttja. Sedimentation chronology supplemented with 14C and 210Pb radioisotopes is used as a tool for identification of past high-magnitude geomorphic processes on debris slopes. Lichenometrically dated debris flow tracks on the slopes are partly correlated with lacustrine minerogenic sediments. -Author

Impacts of old, comparatively stable, treethrow microtopography on soils and forest dynamics in the northern hardwoods of Michigan, USA

Article

May 2016
CATENA

Uprooting represents a key disturbance process in forests, forming pit-mound microtopography, which can then dramatically impact pedogenesis and the forest ecology. At our study sites in northern Michigan, where well-drained, sandy Spodosols dominate, pit-mound microtopography tends to persist for millennia. Because of its persistence, the influence of this type of microtopography is greater here than in most forests. In that respect, our sites represent an end member along a continuum of forest soil disturbance by uprooting. We studied post-uprooting pedogenesis (at 14 dated pit-mound pairs), mapped and characterized the pit-mound topography (over 2.8 ha), the soils below (within 317 soil profiles), and the trees above, to better understand the complex interactions among this type of disturbance regime and forest dynamics.

The significance of trees and coarse woody debris in shaping the debris flow accumulation zone (North slope of the Babia Góra Massif, Poland)

Article

Mar 2007

M. Matyja

In August 2002 a debris flow with a total length of 760m occurred on the northern slope of Poland's Mount Babia Góra. The deposition zone stretched across a distance of 280m laying entirely within upper montane-zone spruce forest. The objective of this study was to determine the influence of trees and coarse woody debris (CWD) on transport and deposition processes within the deposition zone, and to estimate the length of time during which CWD influences slope processes. The greatest influence on deposition processes was found to be exerted by the presence of CWD lying perpendicular to the debris flow axis. The 53% of CVVD laying in the path of debris flow formed steps intercepting deposits and slowing down surface runoff. The impact of standing trees on depositional processes is seen to be of secondary importance. On the other hand, piles of debris more than 1m in height on the up-slope side of trees are stable enough to change the direction of flow. Also the larger CWD is able to change or deflect the path of debris flow. The relative decrease in velocity caused by trees and CWD ranges from 6% to 53%. This study shows that, in the case of low-energy debris flow, CWD and trees can significantly change the flow morphology, decreasing its velocity and range, and increasing sinuosity (Si=1.3). The CWD enhances the roughness of the slope surface and restricts the delivery of deposits to the valley bottom. Dating of CWD shows that its decay time in aerial conditions is 100-150 years.

The morphogenetic role of foehn wind in the Tatra Mts

Article

Jan 1970

A. Kotarba

The role of severe windstorms in modifying the mountain forest floor relief; A case of the blowdown area in the Slovakian High Tatras

Article

Jan 2010

Elżbieta Rojan

Mountain environments are typified by frequent landscape changes. In recent years, extreme events such as catastrophic windstorms have repeatedly occurred and the resultant changes are best recognized within the mountain forest zone. Apart from vegetation, the relief of the forest floor experiences substantial modification. Surface changes in the blowdown area (12 600 ha), resulting from the windstorm of 19 th November 2004 in the Slovakian High Tatras, are the subject of this study. The wind, called the Tatra bora, achieved the velocity of 64 m/s (230 km/h). Catastrophic results were facilitated by simple species composition of the forests with prevailing spruce (72% of the trees) and some admixture of larch. The direct change to the forest floor relief was the result of tree uprooting which caused an uplift of substantial amount of soil and bedrock. Ten plots of 400 to 1600 m 2 each, situated in characteristic places within the blowdown area, were selected for the detailed study. The uplifted roots of a tree with attached soil and rocks create a kind of a disc, hereafter referred as the uprooted tree. Following measurements of such disks (uprooted trees) were performed: the longest axis (a), the shortest axis (b) and the thickness (c). It was calculated that the average area affected directly by a single uprooted tree was 2.58 m 2 and the estimated total area of the direct relief modification constituted 8,2% of the whole blowdown area. The average volume of a single uprooted tree was 1.9 m 3 and the estimated total volume of uplifted soil and rocks was 7.7 km 3. The occurrence of freshly uprooted trees triggered further relief modification - small pits and mounds have developed next to the roots. The pits and mounds have become relatively stable with longest axis up to 6 m, depths and heights up to 0.6 m. Such secondary landforms develop due to denudation and plant colonisation which stabilizes the relief. Such micro-topography can constitute approximately 50% of the blowdown areas of the world. The Slovakian blowdown area is yet too young for detailed measurements of the resulting micro-topography since the pits and mounds did not yet develop fully. However, based on the performed studies, it can be inferred that pits and mounds will cover 10% of the whole area affected by the windstorm. Denudation within the uprooted trees and their direct surroundings has little impact on the overall efficacy of slope processes. Removal of fallen trees by heavy machinery can pose significant threats to the mountain environment. Cartographic materials and field studies allow to state that: 1) new roads were created, 2) existing roads were widened (sometimes even two times - up to 6 m), 3) the roads were deepened - by as much as 0.5 m during 4 months), and 4) the function of certain roads was changed permanently or temporarily. The main direction of mobility of the machinery working in the forest was parallel to the slope profiles, even when the slope inclination exceeded 20°. The forest works, conducted since September 2006, resulted in the lengthening of the roads by as much as 3 to 4 times. However, 2-3 years after cessation of intensive works the roads became overgrown, sometimes completely. Installed bench marks allowed determining changes in cross-sections of the roads in 13 different places. However, this was possible only after cessation of intensive works, which was the period of highest human pressure. Natural geomorphic processes shape the roads afterwards. It was found that accumulation slightly prevails over erosion, which is explained by woody debris accumulation on floors of road incisions. The range and duration of relief modification within the mountain blowdown areas depend on slope inclination, lithology, and the type and timing of human activity.

Geomorphic hazards in the Polish Flysch Carpathians

Article

Jan 2006

L. Starkel

The carpathians and their foreland: Geology and hydrocarbon resources

Article

Jan 2000

The influence of tree roots on soil morphology

Article

Jun 1939

The protective role of trees in soil conservation

Article

Feb 2005

C. O'Loughlin

The impacts on slope stability of Cyclone Bola in 1988 and the February storms in Wanganui-Manawatu in February 2004 provided strong evidence that treeless steepland is very vulnerable to mass wasting during large cyclonic storms whereas forested slopes are relatively resistant to failure. The evidence from numerous studies indicates it is the tree root systems which provide most of the additional resistance. This paper briefly reviews the influence of trees on shallow landslides with most of the emphasis on radiata pine. The relatively rapid development of radiata pine root systems enables this species to provide good soil reinforcement after about 10 years of growth but within a few years after harvesting, most of the root reinforcement is lost. The various approaches that can be adopted to manage forests for soil protection, and identify where the most landslide-vulnerable slopes or parts of slopes are located, are outlined. Modern computer models, in combination with GIS, provide very useful predictions of instability.

Holocene reactivations of catastrophic complex flow-like landslides in the Flysch Carpathians (Czech Republic/Slovakia)

Article

Jul 2013
QUATERNARY RES

Complex flow-like landslides (CFLLs) are important geomorphic agents of Late Quaternary mountain evolution in the Flysch Belt of the Outer Western Carpathians. The CFLLs are characterised by the upper section of deep-seated, retrogressive landslide of structurally unfavourably oriented rocks and lower sections composed of earthflows originated due to liquefaction of material accumulated from the upper slopes. Radiocarbon dating of organic matter incorporated into landslide debris or related deposits suggests that most of the CFLLs collapsed repeatedly throughout the Holocene with typical recurrence intervals of approximately 1–2 ka. Catastrophic landslides that occurred during extreme hydrometeorological events in recent decades displayed evidence of Holocene activity. Most of the CFLLs dammed and steepened adjacent valleys. Our chronological dataset is biased by erosion of older landforms, but most of the dated reactivations correlate to regional increases in humidity identified by previous paleoenvironmetal studies.

Hillslope Form and Process

Article

Feb 1973

Soil mixing and genesis as affected by tree uprooting in three temperate forests: Soil mixing and evolution as affected by tree-throw

Article

Mar 2015
EUR J SOIL SCI

The purpose of this study was to identify general patterns of pedoturbation by tree uprooting in three different, forested landscapes and to quantify post-disturbance pedogenesis. Specifically, our study illustrates how the effects of ‘tree-throw’ on soils gradually become diminished over time by post-uprooting pedogenesis. We studied soil development within 46 pit-mounds in two regions of the Czech Republic, one on Haplic Cambisols and one on Entic Podzols. A third study site was in Michigan, USA, on Albic Podzols. Uprooting events were dated by using tree censuses, dendrochronology and radiometry. These dates provided information on several chronosequences of pedogenesis in the post-uprooting pits and mounds, dating back to 1816 AD (dendrochronological dating, Haplic Cambisols), 322 AD (median of calibration age, 14C age = 1720 ± 35 BP, Entic Podzols) and 4077 BC (14C age = 5260 ± 30 BP, Albic Podzols). Post-uprooting pedogenesis was most rapid in pits and slowest on mounds. Linear chronofunction models were the most applicable for pedogenesis, regardless of whether the soils were in pit or mound microsites. These models allowed us to estimate the time required for horizons in such disturbed sites to obtain the equivalent thicknesses of those in undisturbed sites. These ranged from 5 (O horizon in pits on the Haplic Cambisols) to > 16 000 years (E horizon on mounds on the Albic Podzols). On the Albic Podzols, development of eluvial and spodic horizon thicknesses suggested that pathways involving divergent pedogenesis may occur at these small and localized spatial scales.

Spatial distribution of channel heads in the Polish Flysch Carpathians

Article

Apr 2015
CATENA

Hillslope Materials and Processes

Article

Jan 1994

Geomorphological impacts of a tornado disturbance in a subtropical forest

Article

Feb 2015
CATENA

We studied tree uprooting associated with an EF2 tornado that touched down in portions of the Ouachita Mountains in western Arkansas in 2009. In the severe blowdown areas all trees in the mixed shortleaf pine–hardwood forest were uprooted or broken, with no relationship between tree species or size and whether uprooting or breakage occurred. There was also no significant relationship between tree species and amount of soil displaced, and only a weak relationship between tree size and rootwad size. Uprooting resulted in a mean bioturbation rate of 205 m3 ha− 1 (about 240 t ha− 1). Direct transfer of wind energy via tree uprooting to geomorphic work of soil displacement was about 75 to 190 J m− 2. Given the infrequency of tornadoes, this energy subsidy is minor with respect to the long-term energetics of pedogenesis and landscape evolution. However, it does represent a highly significant pulse of geomorphically-significant energy relative to other mechanical processes. Tornadoes such as that of April, 2009—not atypical for the region—are disturbances causing severe, non-selective impacts within the affected area. At a broader, landscape scale, tornadoes are highly localized disturbances, and occur infrequently within any given landform element or forest stand. Only about a third of the uproots revealed root penetration of bedrock, compared to about 90% in other areas of the Ouachita Mountains. This is attributable to the thicker colluvial soils at the study site, and is consistent with the idea that root–bedrock interaction is more likely in thinner regolith covers.

Domination of hillslope denudation by tree uprooting in an old-growth forest

Abstract

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