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Biogeomorphology and contingent ecosystem engineering in karst landscapes

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Abstract

While karst is not biogenic in the same sense as, say, coral reefs or peat bogs, and carbonate dissolution can occur abiotically, formation of karst landscapes would not occur in the absence of the biosphere. Seven levels of biogeomorphic biotic-abiotic interactions are identified, from indirect impacts to landforms as extended phenotypes. Karst is generally near the biogenic end of that spectrum, featuring reciprocal interactions and mutual adjustments between biota and landforms and interrelated geomorphological and ecological processes. Karst biogeomorphology may also involve niche construction. In many cases biogeomorphic ecosystem engineering in karst is contingent, in the sense that the engineer organisms may have no, or different, biogeomorphic impacts in non-karst environments. Several examples of contingent ecosystem engineering in karst are given, including biogeomorphic effects of chinkapin oak. Abiotic geomorphic features exist on Earth, but consideration of landform types lying between the biotic-abiotic extremes would likely yield broadly similar conclusions to those about karst. However, it is also clear that we know very little about niche construction and coevolution in karst biogeomorphology, and whether karst or any specific karst features can be considered an extended (composite) phenotype is still an open question. Thus far, most work on biogeomorphology and ecosystem engineering has focused on what might be called obligate engineers—organisms whose engineering effects are at least inevitable, if not necessary to their survival. However, in some cases contingent ecosystem engineers have substantial geomorphic impacts.

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... In addition to the structural, lithological and climatic controls, plantnutrient acquisition and root exudates play a key role in soil formation and geomorphological processes at scales that range from individual sand grains to hillslopes due to rock dissolution and nutrient mobilization (Phillips et al., 2008;Phillips and Marion, 2006;Pate, 2006, 2013;Viles et al., 2008;Gabet and Mudd, 2010;Roering et al., 2010;Corenblit et al., 2011;Brantley et al., 2011;Pawlik et al., 2016a;Pawlik and Šamonil, 2018a,b;Pérez, 2012Pérez, , 2017Dontsova et al., 2020;Zaharescu et al., 2020). Biological weathering has long been recognized (Lucas, 2001); however, the association between plant roots, bedrock weathering and sediment transport has only recently been studied systematically (Temmerman et al., 2007;Davies and Gibling, 2013;Eichel et al., 2016;Phillips, 2016;Šamonil et al., 2017;Schwarz et al., 2018). ...
... Bioweathering by roots determines rock displacement, whereas mass movement processes operating within a hillslope affect morphology and shapes the landforms. Bioweathering also influences the connectivity between different landscape compartments (Marston, 2010;Phillips, 2016;Wohl et al., 2018). ...
... Without the plant cover, the joints and bedding planes would still be densely compacted with slow rates of physical and chemical weathering. The biotic arenization, in this case, accelerated the rockfall process and slope formation by feedback dynamics between landforms and functional traits of Velloziaceae, which we can define as biogeomorphic engineers (Jones, 2012;Phillips, 2016). ...
Article
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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.
... My supraorganic view is partly an outgrowth of considering Earth surface systems (ESS) as expressions of the combined, interacting effects of biota as well as abiotic factors. I have made the case that both soils and landforms are extended composite phenotypes (Phillips 2009(Phillips , 2016a. ...
... Some landformsdfor instance, volcanic features, dunes in hyperarid deserts, or glacial scoursdare created independently of any significant direct biological influences. However, many landforms may also be considered ECP, independently of the soils they are associated with (Phillips, 2016a;Corenblit et al., 2016). It is axiomatic that many landforms and geomorphic processes are strongly influenced by biota, that geomorphological and ecological processes are often closely intertwined, and that landforms and surface processes are key components of the ecological framework for many organisms. ...
... The argument for landforms as ECP is based on process-form relationships, synchrony, selective pressure, and positive feedback (Phillips, 2016a). The first involves demonstrating that actions of one or more organisms can create or strongly influence the development and characteristics of a landform. ...
Chapter
Ecosystems and landscapes are supraorganisms (not superorganisms), defined as highly interconnected biotic-abiotic systems which meet two criteria: (1) Significant changes to any component result in changes to the system as a whole, and responses and adaptations occur at the ecosystem level (in addition to responses of ecosystem constituents) and involve multiple system components. (2) Developmental and evolutionary changes occur contemporaneously within the system. This does not imply simultaneity but does require that changes within the ecosystem are contemporaneous or temporally overlapping. This points to an approach to landscape evolution that confronts the holistic nature of historical development and responses to environmental change, rather than (or in addition to) evolution or responses of individual constituents such as biota, soils, or landforms.
... However, their influence on weathering processes, and especially weathering processes in the Devonian, still awaits full exploration. Jonathan D. Phillips proposed biogeomorphic ecosystem engineering (BEE) concept and illustrated their effectiveness in karst landscapes (Phillips, 2016a(Phillips, , 2018 and forested hillslopes . This term is similar to 'biogeomorphic engineering' (Francis et al., 2009) for erosion and accumulation processes induced by vegetation communities in fluvial systems. ...
... This term is similar to 'biogeomorphic engineering' (Francis et al., 2009) for erosion and accumulation processes induced by vegetation communities in fluvial systems. The ecosystem engineering is considered biogeomorphic when it involves biotic effects on landforms and geomorphic processes (Phillips, 2016a). The concept built primarily on Jones et al. (1994Jones et al. ( , 1997 works but also the idea of extended phenotype (Dawkins, 1982(Dawkins, , 2004Mitton, 2003) applied then to soils and landforms (Phillips, 2009b(Phillips, , 2016b. ...
... Earth-Science Reviews 205 (2020) 103200 (Beerling, 2007;Harrison et al., 2010). However, ecological filtering can occur that negatively impacts particular taxa (Phillips, 2016a). In terms of trees this has been demonstrated by Binkley and Giardina (1998), who suggested that a tree species can modify soils to the disadvantage of other species. ...
Article
Full-text available
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?
... Microorganisms interact with minerals and promote bioweathering (Naylor and Viles, 2002) and biomineralisation processes (Barton and Northup, 2007;Riquelme et al., 2015). They can also have an important, albeit poorly understood, role in ecosystem engineering (Phillips, 2016). The key biogenic and biochemical processes that create distinctive morphological features in caves are: i) microbially-mediated mineral dissolution, and ii) microbially-mediated mineral precipitation (Riquelme et al., 2015). ...
... Here we have sought to address some of these knowledge gaps by investigating the microbiogeomorphic processes developing at the entrance, twilight and dark zones of a flank margin cave system (Lighthouse Cave) located in the Bahamas. In addition, we attempted to identify consistent biogeomorphic features and/or processes that can be associated with ecosystem engineering and likely to construction niches sensu Phillips (2016). Hence, the aim of this study was to understand how biological processes can influence eogenetic carbonate rocks in the development of peculiar micromorphological features (e.g., mineral precipitation, pitting/etching, boreholes) in zones of the cave system with different natural light conditions, and assess how present (post-mixing) flank margin cave evolution may be influenced by secondary bioweathering or bioconstruction processes. ...
... Light attenuation plays an important role in influencing the behaviour of biological communities involved in landform processes, bioweathering and bioconstruction within the underground environment. As suggested by Phillips (2016), light attenuation is an interesting candidate for "niche construction". Niche construction means that biogeomorphic ecosystem engineering influences natural selection (such as stromatolite formation and/or Ca-nitrate precipitation in dry cave deposits). ...
Article
San Salvador (Bahamas) is a carbonate island with dozens of flank margin caves formed in the phreatic zone by fresh seawater mixing within the freshwater lens. These caves have no direct connection with the sea, and form at or close to the tidally influenced fluctuating water table. After sea-level fall, in their subaerial parts caves are enlarged mainly by rock dissolution and by erosion close to the water level, condensation-corrosion and breakdown processes. For understanding the geomorphological features observed in these caves and how they are related to light attenuation, we investigated three sampling sites in the tidally influenced zone of Lighthouse Cave, which has been re-invaded by seawater during the Holocene sea-level highstand. A freshwater lens no longer exists within or adjacent to the cave. Rock samples were collected above and below the internal lake shores close to the entrance, and in the twilight and dark zones of this cave. Light and electron microscopy examinations were conducted for detecting microbial cells, as well as bioconstruction and bioweathering features. In addition, a high precision laser scanner was used for characterising sample microtopography. Our data showed that the microtopography and geomorphology of the lake shore samples (cave entrance) are dominated by bioweathering, whereas the samples of the twilight and dark zones are controlled by a combination of both bioweathering and bioconstructive processes depending on light availability. Bioconstructive structures, such as semi-planar lamination, at the fluctuating water level of the Lighthouse Cave show that dissolution due to water mixing of sea and freshwater in the Holocene is no longer the most important speleogenetic process. We propose that the geomorphological evolution is strongly influenced by the degree of rock diagenesis more than the initial mechanism of speleogenesis.
... An increasing number of studies in the field of microbial biogeomorphology (section 3.7) are also starting to highlight the role of microbial rock weathering communities in the shaping of a wider range of geological environments, including caves and coastal areas (Coombes et al., 2015;Engel et al., 2004;Phillips, 2016;Viles, 2012). This chapter aims to introduce the reader to the core concepts of microbial weathering of minerals and rocks in natural environments, from the mechanisms that operate at the micron scale to their effects that directly alter and shape the geological landscape of this planet. ...
... For example, an active weathering mechanism of an organism is more likely to be a necessary requirement for growth, and therefore the presence of that organism within an environment is likely to be concurrent with evidence for that activity. In contrast, a passive mechanism might only be carried out under specific environmental conditions (Phillips, 2016;Uroz et al., 2009). Understanding this distinction is necessary to fully comprehend the implication of identifying microbial species within rock weathering environments. ...
... However, microbial rock weathering processes can also make significant contributions to biogeomorphology (Coombes et al., 2015;Phillips, 2016;Viles, 2012). The formation of sulfur caves provides a good example, where microbial sulfuric acid production is the primary agent driving cave formation (Boston et al., 2006;Engel et al., 2004). ...
Chapter
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Microbes are active agents of environmental change. From the depths of the Earth’s crust to the heights of the upper atmosphere, microorganisms alter the physicochemical conditions surrounding them. Their activity provides important ecosystem services to the wider biosphere, making essential elements such as carbon, sulfur, phosphorus and iron available for higher organisms. One such environmental interaction is the weathering of minerals and rocks by microbial communities, a key process that underpins soil formation and global biogeochemical cycles. By facilitating mineral dissolution and rock degradation, microbes enhance the release of elements from their geological reservoirs and perform significant elemental transformations. Under what conditions microbes perform these activities and to what extent they impact their surrounding environment, are key topics in geobiology. In this chapter, various aspects of microbial mineral and rock weathering will be explored. Key concepts and terminology will be introduced, followed by an overview of the mechanisms used by microorganisms to perform weathering activity. Sections covering the methodological approaches used by researchers to study microbial rock weathering processes, including detecting the traces or “biosignatures” such microbial activity leaves behind on geological materials, will be provided. The effect of microbial rock weathering on the wider microbial ecosystem, including the endurance and functional capacity of microbial communities, is also explored. Finally, this chapter will discuss the emerging field of microbial biogeomorphology, the study of how biological activity at the micron scale can impact the environment at metre to kilometre scales, contributing to the processes that shape Earth’s landscapes.
... Phillips (2015) showed that about 90% of the examined trees of his study conducted on limestone bedrock hillslopes exhibited evidence of: i) joint widening both horizontally and vertically by root penetration; ii) mechanical displacement of bedrock along bedding planes; and iii) root exposure indicating the removal of material at the tree base (Table 3). Phillips (2016) further explained how the widening of joints can promote chemical weathering in such karst-associated bedrock environments. A combination of root growth in joints, trunk expansion, and the development of basal flares near the tree-ground interface can displace rock fragments both vertically and horizontally (Phillips, 2015). ...
... The right corner of the triangle indicates BGIs that are highly concentrated in bedrock hillslopes. Infilling of stump holes and trapping of sediments from upslope (bioconstruction and modification) (Pawlik, 2013, Shouse andPhillips, 2016) are distinctive BGIs within rocky hillslopes, while fluvial environments have limited potential to display such impacts. ...
... ;Pawlik (2013);Phillips and Marion (2006);;Schaetzl et al. (1989);Small et al. (1990); Šamonil et al. (2010). Bedrock mining associated with tree uprootingPawlik (2013);Phillips (2015);Phillips (2016).Displacement of bedrock by root and trunk growthBirot (1966);Gabet and Mudd (2010);Gabet et al. (2003); Jackson andSheldon (1949);Lutz and Griswold (1939); Matthes-Sears and Larson (1995); Phillips(2015);Roering et al. (2003). Accelerated weathering along joints and bedding planesBormann et al. (1998);Gabet et al. (2003);Marion (2005Marion ( , 2006;Phillips and Phillips (2015);Yatsu (1988). ...
Article
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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.
... Karst landscapes are a typical example of landforms resulting from reciprocal biotic-abiotic interactions (Phillips, 2016b). Slow dissolution of calcite can occur in water with CO 2 from the atmosphere being the only source of acidity. ...
... Geomorphic and biological processes in a landscape have been largely conceptualized as independent, and reciprocal interactions between the two have been only recently acknowledged (Swanson et al., 1988;Bendix and Hupp, 2000;Stallins, 2006;Murray et al., 2008;Hupp et al., 2016;Phillips, 2016b). It is increasingly recognized that for some systems, broad scale landscape topography arises from feedbacks between geomorphic and ecological processes, i.e. biogeomorphic feedbacks. ...
... The strength of biogeomorphic feedbacks in shaping landforms varies among systems, ranging from weak indirect impacts to strong direct impacts (e.g. landforms as extended phenotypes; Phillips, 2016b). At one extreme, landscape topography could be controlled directly by biological behaviors, coupled with geomorphic processes. ...
... This micro-topography is shaped by karst processes, and the vegetation, in turn, influences moisture balances and fluxes, organic matter accumulation, and soil chemistry that strongly influence karst dissolution (Sullivan, Price, Ross, & Sklar, 2016;Watts et al., 2014). The plant species involved occur in non-karst settings in the region, and Phillips (2016) interpreted the BEE effects as contingent on the karst setting. He provided an additional example of contingent BEE in karst from central Kentucky, based on effects of a specific tree species on weathering and soil thickness (Phillips, 2016). ...
... The plant species involved occur in non-karst settings in the region, and Phillips (2016) interpreted the BEE effects as contingent on the karst setting. He provided an additional example of contingent BEE in karst from central Kentucky, based on effects of a specific tree species on weathering and soil thickness (Phillips, 2016). ...
... The effects discussed here are also likely to be spatially heterogeneous. The soil conditions created by trees, nutrient-rich microsites associated with decomposing trunks and roots, and local concentration of seeds and root stock make it likely that trees preferentially reoccupy the same locations over multiple generations of forest (Finke, Vanwalleghem, Opolot, Poesen, & Deckers, 2013;Kooch, Hosseini, Scharenbroch, Hojati, & Mohammadi, 2015;Moghimian, Jalali, Kooch, & Rey, 2017;Phillips & Marion, 2004;Sullivan et al., 2016;Van Lear, Kapeluck, & Carroll, 2000), evidence of which was found at sites in and near the Inner Bluegrass study area (Phillips, 2016;Shouse & Phillips, 2016). This phenomenon, in combination with the theoretical model presented here, suggests a highly variable spatial pattern of regolith thickness due to tree effects, where the general thickness is greater than or equal to rooting depth, with more uniform thickness otherwise. ...
Article
Tree roots have biogeomorphic engineering effects on epikarst weathering and soil deepening. This is investigated using a system model describing the interactions among biogeomorphic effects of roots, weathering, and soil-epikarst development. The model shows that the system is dynamically unstable when roots are limited by subsurface accommodation space and water availability, and weathering is moisture limited. Instability indicates relatively rapid, unstable growth of epikarst cavities and soil, driven by positive feedbacks. However, when belowground rooting space and moisture are no longer limiting, and weathering is reaction-limited, the system is dynamically stable, indicating steady state or slow growth of epikarst and soils. Results suggest an important role for biogeomorphic ecosystem engineering (BEE) by tree roots in soil and epikarst development, but that BEE is self-limiting. When moisture storage and supply for both plants and dissolution are adequate and sufficient root space is available, BEE effects become negligible. Supportive data and field observations from the Inner Bluegrass region of Kentucky indicate that BEE effects of trees can produce favorable conditions for tree growth, with these effects becoming negligible as soil thickness increases sufficiently.
... Recent decades have seen changes in this process though, as research on biophysical interactions have gained more interest (Jones et al. 1994;Reinhardt et al. 2010). 80% of all geomorphological changes can be attributed to ecosystems in karst areas (Phillips 2016). Ecologists have long been aware of the interdependence of populations and the natural environment in an ecosystem (Corenblit et al. 2011). ...
... The characteristics and the size of the habitats' geomorphological niche dynamics are modified by physical state changes, so the landscape creating skills of ecosystem engineers are made use of, thus making it possible for other species to appear in the ecosystem (Corenblit et al. 2010). These studies proved that living organism do not only respond to the changes of their physical environment, but they can also modify and control them directly, and by doing so they change the characteristics of natural landscapes (Viles 1988;Phillips 2016). It is now proven that ecosystems mutually interact with their natural (physical) environment through biogeochemical cycles, which serve as the basis of energy flows and nutrient cycles. ...
... Morphological characteristics are affected by soil microorganisms which, by decomposing soil organic matter, produce CO2 and increase the carbonic acid content of the solvent water, hence these microorganisms are ecosystem engineers. Both indirect (microclimate, soil, etc.) and direct effects are important in biological weathering (root acids) (Jakucs 1980;Bárány Kevei 1998;Phillips 2016). Corals directly influence morphological development as they build coral reefs and barriers (by colonies of tiny corals and a photosynthetic alga species). ...
Article
Full-text available
In the last decades, the research on ecosystem services have emerged in the field of geography. The negative impacts of human activities on the vulnerable karst areas are getting enforced quickly, which have an unfavourable influence on ecosystem service provision. On karstic areas, there are significant geographical processes, connected to biological activities. This issue is not adequately discussed in the current literature of karst ecology. In our study, we give an overview on the biogeomorphological feedbacks that change the functions and overall value of karst ecosystems.
... Several observations exist which suggest that roots enhance rock weathering, but that this is controlled by rock body properties, mainly the existing network of joints, cracks and fissures (Zwieniecki and Newton, 1995;Little and Field, 2003;Phillips et al., 2008a;Phillips, 2016a). ...
... 25 soil (Gaiser, 1952). It is evident in a very porous immature soils developed in karst areas (Martin, 2006;Phillips, 2016a). Such conditions inevitably influence the presence of rhizospheres (Schwinning, 2013). ...
... Grooves develop along living roots in contact with rock due to chemical weathering associated with moisture moving along the root, respiration and transpiration by the root, organic acids, and associated effects of microbes (Wall and Wilford, 1966;Sweeting, 1973;Bull and Laverty, 1982;Trudgill, 1985;Taborosi, 2002). Such features may be an initial point of self-reinforcing mechanisms of further rock dissolution, especially in carbonate rocks, where these features are most common (Phillips, 2016a). Existing root grooves act as pathways of rapid rain water percolation. ...
Article
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.
... The geoecological system of karsts is a complex system (Bárány Kevei 1998ab, Daoxian 2001, Venhua and Jianhua 2015, Phillips 2016). The geoecological system of dolines (as a local subsystem of karsts) is a structural and dynamic system in which the abiogenic elements are rocks, water, soil, macro-and microclimate, while the biogenic elements are micro-and macroflora, and man. ...
... The composition of the vegetation on limestone surfaces is studied by international and national researchers in several directions (Brancelj 2006, Corenblit 2011, Efe 2014, Ramsey 2015, Phillips 2016, Meixian et al. 2016. In Hungary, Bacsó and Zólyomi (1939) were the first who addressed the interaction between karstification and vegetation, they were followed by Jakucs P (1956). ...
Article
Full-text available
In this study the changes in the nighttime heat load in Carpathian Basin cities during the 21st century were examined. To quantify the heat load, the tropical night climate index was used. The MUKLIMO_3 local scale climate model was used to describe the urban processes and the land use classes were defined by the local climate zones. The expected change was examined over three periods: the 1981–2010 was taken as reference period using the Carpatclim database and the 2021–2050 and 2071–2100 future periods using EURO-CORDEX regional model simulation data for two scenarios (RCP4.5 and RCP8.5). To combine the detailed spatial resolution and the long time series, a downscaling method was applied. Our results show that spectacular changes could be in the number of tropical nights during the 21st century and the increasing effect of the urban landform is obvious. In the near future, a slight increase can be expected in the number of tropical nights, which magnitude varies from city to city and there is no major difference between the scenarios. However, at the end of the century the results of the two scenarios differ: the values can be 15-25 nights in case of RCP4.5 and 30-50 nights in case of RCP8.5. The results show that dwellers could be exposed to high heat load in the future, as the combined effect of climate change and urban climate, thus developing various mitigation and adaptation strategies is crucial.
... The geoecological system of karsts is a complex system (Bárány Kevei 1998ab, Daoxian 2001, Venhua and Jianhua 2015, Phillips 2016). The geoecological system of dolines (as a local subsystem of karsts) is a structural and dynamic system in which the abiogenic elements are rocks, water, soil, macro-and microclimate, while the biogenic elements are micro-and macroflora, and man. ...
... The composition of the vegetation on limestone surfaces is studied by international and national researchers in several directions (Brancelj 2006, Corenblit 2011, Efe 2014, Ramsey 2015, Phillips 2016, Meixian et al. 2016. In Hungary, Bacsó and Zólyomi (1939) were the first who addressed the interaction between karstification and vegetation, they were followed by Jakucs P (1956). ...
Article
Full-text available
In this study the changes in the nighttime heat load in Carpathian Basin cities during the 21st century were examined. To quantify the heat load, the tropical night climate index was used. The MUKLIMO_3 local scale climate model was used to describe the urban processes and the land use classes were defined by the local climate zones. The expected change was examined over three periods: the 1981–2010 was taken as reference period using the Carpatclim database and the 2021–2050 and 2071–2100 future periods using EURO-CORDEX regional model simulation data for two scenarios (RCP4.5 and RCP8.5). To combine the detailed spatial resolution and the long time series, a downscaling method was applied. Our results show that spectacular changes could be in the number of tropical nights during the 21st century and the increasing effect of the urban landform is obvious. In the near future, a slight increase can be expected in the number of tropical nights, which magnitude varies from city to city and there is no major difference between the scenarios. However, at the end of the century the results of the two scenarios differ: the values can be 15-25 nights in case of RCP4.5 and 30-50 nights in case of RCP8.5. The results show that dwellers could be exposed to high heat load in the future, as the combined effect of climate change and urban climate, thus developing various mitigation and adaptation strategies is crucial.
... A combination of competition between basins for water resources seems likely to be the positive feedback on basin expansion, while inhibitory feedbacks may be imposed as basins expand and shrink the contributing upland area necessary to subsidize basin hydroperiod. This scale-specific negative feedback is not general to karst landscapes, but it does further highlight the role of biotic and hydrologic interactions in creating the myriad patterns observed in karst settings around the world (Phillips, 2016). ...
... First, the patterning process is slow, unfolding over time scales far longer than the generation length of the individual biological agents responsible for the process. This has interesting implications for the invocation of the extended phenotype concept (Corenblit et al., 2011;Phillips, 2016) in which organisms modify their environment to their benefit. In this case, the wetland depressions can contain trees (typically cypress) or not, suggesting that no obvious ecosystem engineer is responsible for the process, but rather all wetland taxa, including the microbes responsible for the organic matter mineralization reactions, create and benefit from basin evolution (Ehrlich, 1996). ...
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Thousands of small wetland depression features (cypress domes) dot the low‐relief karst of Big Cypress National Preserve (BICY) in South Florida, USA. We hypothesized that these wetland depressions are organized in a regular pattern, which is atypical of wetlandscapes elsewhere. Regular patterning implies the existence of coupled feedbacks operating at different spatial scales, with local wetland depression expansion (facilitation via karst dissolution) limited by competition among adjacent depressions for finite water resources (inhibition). We sought to test the hypothesis that wetlands in BICY exhibit regular patterning, and to quantify pattern properties to evaluate competing genesis mechanisms. We tested four predictions about landscape structure and geometry using high‐resolution Light Detection and Ranging elevation data from six 2.25‐km² domains across BICY. Specifically, we predicted (1) feature overdispersion resulting from competition between adjacent basins; (2) truncated wetland area distributions due to growth inhibition feedbacks; (3) periodicity in surface elevation indicating a characteristic pattern wavelength; and (4) elevation bimodality indicating distinct upland and wetland states. All four predictions were strongly supported. Depressions were significantly overdispersed and efficiently fill the landscape, generating hexagonal patterning. Wetland areas followed truncated power law scaling, indicating incremental constraints on basin expansion, in contrast to depression areas elsewhere. Variogram and radial spectrum analyses revealed clear periodicity (~150‐ to 250‐m wavelength) in surface elevations. Finally, surface elevations were consistently bimodal with elevation divergence of 10 to 40 cm. Regular patterning of wetland depressions across BICY is clear, implying long‐term biogeomorphic control on landform structure in this karst landscape.
... Retained CO 2 gas plays an important role in local land patterning by carbonate dissolution and the formation of biokarst landscapes (Phillips, 2016;Watts et al., 2014). This dissolution results from OM decomposition (biogenic CO 2 and organic acids), which contributes about 80% of weathering in subtropical karst and about 93% in tropical karst, as a result of higher respiration rates and air temperature in the warm climate (Phillips, 2016). ...
... Retained CO 2 gas plays an important role in local land patterning by carbonate dissolution and the formation of biokarst landscapes (Phillips, 2016;Watts et al., 2014). This dissolution results from OM decomposition (biogenic CO 2 and organic acids), which contributes about 80% of weathering in subtropical karst and about 93% in tropical karst, as a result of higher respiration rates and air temperature in the warm climate (Phillips, 2016). Thus, wetland development in BICY is likely a result of extensive vegetation growth in the wetlands, especially in the center, that lead to accumulation and respiration of OM in sediments. ...
Article
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Biological processes exert important controls on geomorphic evolution of karst landscapes because carbonate mineral dissolution can be augmented and spatially focused by production of CO2 and biogenic acids from organic matter (OM) decomposition. In Big Cypress National Preserve in southwest Florida, depressional wetlands (called cypress domes) dissolved into surface-exposed carbonate rocks and exhibit regular patterning (size, depth, and spacing) within the pine upland mosaic. To understand when wetland basins began to form and the role of spatially-varying OM decomposition on bedrock weathering, we constructed age profiles of sediment accretion using compound-specific radiocarbon analysis (CSRA) of long-chain fatty acids and measured bulk OM properties and biomarker proxies (fatty acids and lignin phenols) in different zones (center vs. edge) of the wetlands. Based on CSRA, landscape patterning likely began in the mid-to-late Holocene, with wetlands beginning to form earlier at higher elevations than at lower elevations within the regional landscape. Dominant vegetation appears to have shifted from graminoids to woody plants around 3000 cal. BP, as reflected in down-core bulk C isotope data and lignin concentration, likely from increased precipitation and hydroperiods. Organic matter is mostly accumulated in wetland centers and wetland centers exhibit more carbonate dissolution due to inundation limiting atmospheric ventilation of CO2. Landscape development and patterning thus arise from interactions between hydrology, ecology, ecological community evolution that control carbonate mineral dissolution.
... A 2000-es évek morfometriai értékelései (TELBISZ et al 2007, VERESS 2007, BASSO et al 2013, RAMSEY 2015 már hozzájárultak a dolinafejlődés pontosabb megértéséhez és utaltak a különböző környezethatások fontosságára is. Az utóbbi évtizedekben egyre inkább teret nyert a karsztterületek GIS segítségével történő feltárása, és adatbázisok létrehozása (GAO, ALEXANDER 2003, SISKA, KEMMERLY 2007, GAO, ZHOU 2008, 2016, KOBAL et al., 2014. Ezek az adatok segítik a geohazardok előfordulásának előrejelzését is (BRUNO et al 2008). ...
... A növényzet összetételét a mészkő felszíneken mind nemzetközi, mind hazai szinten sokirányúan vizsgálják a kutatók (CORENBLIT 2011, EFE 2013, RAMSEY 2015, PHILLIPS, JD. 2016, MEIXIAN, LIU et aL. 2016, Hazánkban először BACSÓ, ZÓLYOMI (1939) mutatta be egy bükki dolina növényzetétnek és a mikroklímának kapcsolatát, majd JAKUCS P (1956). ...
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The ecological (environmental) system of the karst is very vulnerable, environmental impacts endanger the natural course of corrosion, the survival of individual habitats and the quality of non-renewable natural resources. Incorrect human use may also cause degradation of aesthetic and environmental values. In the karst system, the occurrence and distribution of dolines are related to the characteristics of the climatic conditions of the area. Dolines are "hot spots" of karstic areas, the infiltrating water can enter the system very quickly here, where they can start irreversible (degradation) processes. The development of the dolines is governed by the integrated processes of geo-ecological factors (bedrock, climate, water, soil, vegetation, humans). Karst ecosystem services (drinking water supply, recreational utilization, timber production and carbon sequestration) are of great importance fo the population. Exploring and evaluating these services are important parts of complex investigations. The study draws attention to geoecological doline studies with some typical geochronological parameters
... Locally restricted drainage also apparently allows for the formation of fragipans in some of the siltcap soils. In some cases, the effects of tree roots growing into bedrock joints locally deepens soil due to effects on weathering and mass displacement (Phillips, 2016b). ...
... These locally thicker soils may provide favorable sites for future tree establishment, providing another positive feedback. Evidence supporting these interrelationships has been reported from studies in central Kentucky by Martin (2006), Phillips (2016b, 2018b, and Shouse and Phillips (2016). ...
Article
Nine axioms for interpreting landscapes from a geoscience perspective are presented, and illustrated via a case study. The axioms are the self-evident portions of several key theoretical frameworks: multiple causality; the law–place–history triad; individualism; evolution space; selection principles; and place as historically contingent process. Reading of natural landscapes is approached from a perspective of place formation. Six of the axioms relate to processes or phenomena: (1) spatial structuring and differentiation processes occur due to fluxes of mass, energy, and information; (2) some structures and patterns associated with those fluxes are preferentially preserved and enhanced; (3) coalescence occurs as structuring and selection solidify portions of space into zones (places) that are internally defined or linked by mass or energy fluxes or other functional relationships, and/or characterized by distinctive internal similarity of traits; (4) landscapes have unique, individualistic aspects, but development is bounded by an evolution space defined by applicable laws and available energy, matter, and space resources; (5) mutual adjustments occur between process and form (pattern, structure), and among environmental archetypes, historical imprinting, and environmental transformations; and (6) place formation is canalized (constrained) between clock-resetting events. The other three axioms recognize that Earth surface systems are always changing or subject to change; that some place formation processes are reversible; and that all the relevant phenomena may manifest across a range of spatial and temporal scales. The axioms are applied to a study of soil landscape evolution in central Kentucky, USA.
... The thickness of soil overlying limestone bedrock can impact the rates of dissolution in these systems, with an intermediate soil cover of approximately 1.5 m corresponding to the maximum observed weathering rates (Dong et al., 2018). Production of biogenic carbon dioxide, which is carbon dioxide produced by microbial respiration, organic material decomposition, and plant roots, also enhances dissolution and is necessary for karst formation (Jakucs, 1977;Jennings, 1985;Ford and Williams, 2007;Phillips, 2016). The soils in the sinkholes are likely impacted by the continual dissolution and subsequent changes in surface topography, specifically changes in slope. ...
Article
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An estimated 20% of the world's land surface is underlain by lithologies favorable for karst formation. Karst features (e.g., sinkholes) and soils coevolve, likely influencing local pedogenesis, soil carbon storage, and hydrologic patterns. While karst is widespread, our understanding of the influence of karst geomorphology on pedogenesis remains limited. To better estimate the impact of karst geomorphology on pedogenesis, we characterized nine pedons as a function of landscape position (i.e. toposequence) in two subsidence sinkholes located in the Inner Bluegrass (IB) physiographic region of central Kentucky; we characterized a suite of soil physical, chemical, and mineralogical properties. The IB is underlain by a phosphatic limestone and is susceptible to karst formation. Expectedly, total carbon was greater in lowland positions relative to upland landscape positions. However, inverse relationships between elevation and clay content, selective iron, aluminum, and silicon extracts contradicted previous toposequence trends. Clay mineralogy differs between toeslope and summit positions suggested sediment transport from summit to toeslope positions. Karst geomorphology may limit pedogenesis and facilitate more rapid material export through karst conduits compared to other lithologies. Given the extent of karst terrains and lithologies susceptible to karst formation, future work is needed to understand the magnitude of the impact of karst on pedogenesis and other earth system processes. This article is protected by copyright. All rights reserved
... In Earth sciences, the concept of ecosystem engineering broadly concerns the creation, modification, maintenance, and destruction of landforms by organisms (Corenblit et al., 2008(Corenblit et al., , 2011Jones, 2012;Jones et al., 1994;Phillips, 2016aPhillips, , 2018Stallins, 2006). This idea explicitly recognizes the role of plants, animals, and microorganisms in regulating the shape of the terrestrial surface and the rate of geomorphological processes (Larsen et al., 2021). ...
Article
Ecosystem engineering deals with how one species affects another (or others) via modifying habitat conditions and resource availability. Through the application of this concept, many Earth scientists have assessed the roles of focal species in modulating landscape formation and dynamics. No species, however, lives or evolves in isolation; moreover, few species exist without any engineering effects on their ambient environment. Based on these basic premises, it appears unlikely that any landform on Earth (except, for example, hyperarid desert dunes, recent lava flows, and glacial grooves) exclusively represents the engineering impact of a single species. Thus, surface topography, to some degree, can generally be a combined expression of ≥ two species that mutually interact with each other through their own engineering activities. The purpose of the present research was to review, refine, and expand upon the original ecosystem engineering concept to make it more inclusive and comprehensive. Accordingly, a new concept has been proposed here, the windows of combined ecosystem engineering (WoCEE), to indicate the range within which the relative importance of engineering effects for ≥ two species changes along a gradient, as defined by various abiotic and biotic factors. In support of this novel idea, real-world examples are presented, including ecological succession in terrestrial and coastal dune ecosystems, crab–plant interactions on tidal wetlands, pocket gopher–plant relationships in the grasslands, and biological invasions by exotic mollusks and macrophytes. Notably, there are likely various other examples in nature, provided the spatiotemporal scales at which multiple species play their bioengineering roles correspond to those at which landforms are shaped. This framework represents an important step forward in the realization of true ecosystem engineering and will potentially serve as a unifying theme of biogeomorphology.
... Southwest China mostly comprises rocky desertification areas, soil erosion areas, and poverty-stricken population areas [14]. In Southwest China, karst areas are widespread, with shallow soils, poor continuity, and low land productivity [15]. Studies have shown that Southwest China is very sensitive to climate change, with frequent occurrences of droughts and heatwaves, and the increasing demand for water resources for regional development has exacerbated the impact of extreme events [16]. ...
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Global warming and its associated changes in temperature and precipitation have significantly affected the ecosystem in Southwest China, yet studies that integrate temperature and precipitation changes are inadequate for quantitatively assessing the impacts of extreme events on ecosystems. In this study, the return period of concurrent climate extremes characterized by precipitation deficit and extreme temperature and the spatial and temporal dynamic patterns of their impacts on ecosystems were assessed by using high-precision temperature and precipitation data, as well as NDVI and NPP data collected for the 1985–2015 period. The results show that the 2009 concurrent event had a return period of about 200 years. The return periods of individual climate factors are significantly overestimated or underestimated. Concurrent events significantly reduced the spring and annual Normalized Difference Vegetation Index (NDVI) and net primary productivity (NPP) in Southwest China. The magnitude of the reduction in vegetation greenness and productivity increased with the intensity of concurrent events. Concurrent events beginning in autumn 2009 reduced spring NDVI and NPP by 8.8% and 23%, and annual NDVI and NPP by 2.23% and 7.22%, respectively. Under future climate scenarios, the return period of concurrent events could be significantly shortened, which would have a more severe impact on regional ecosystems.
... In such an environment, karst ecohydrology integrates landscape features with groundwater hydrology and freshwater biology [52]. Studying the organisms present in coastal caves [53][54][55] represents a unique opportunity to highlight species' wide variety and distribution [56][57][58] in the function of the most significant environmental parameters characterizing these transition areas between land and waters of different chemistry. Among these parameters, light attenuation is one of the most relevant [58,59]. ...
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Marine caves are characterized by wide environmental variability for the interaction between marine and continental processes. Their conditions may be defined as extreme for inhabiting organisms due to the enclosed morphology, lack of light, and scarcity of nutrients. Therefore, it is necessary to identify reliable ecological indicators for describing and assessing environmental conditions in these habitats even more than elsewhere. This review aims to provide the state of art related to the application of benthic foraminifera as proxies in the (paleo)ecological characterization of different habitats of marine caves. Special attention was addressed to a research project focused on Mediterranean marine caves with different characteristics, such as extent, morphology, freshwater influence, salinity, sediment type, oxygenation, and organic matter supply. This review aims to illustrate the reliability of foraminifera as an ecological and paleoecological indicator in these habitats. They respond to various environmental conditions with different assemblages corresponding to a very detailed habitat partitioning. Because marine caves may be considered natural laboratories for environmental variability, the results of these studies may be interpreted in the perspective of the global variability to understand the environmental drivers of future changes in marine systems.
... This is generally an extremely slow course, which happens when the roots penetrate the cracks in the weathered bedrock, or produce cracks on their own through root bioengineering. The capability of roots to penetrate into bedrock is likely to increase with plant size and age [40,41]. Therefore, the afforestation areas containing younger trees with smaller trunk diameters likely have shallower root systems, at a depth of about 0-50 cm, whereas the natural forest containing older trees with larger trunk diameters, have deeper root systems at a depth of about 50-100 cm [42]. ...
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An increase in the frequency and severity of droughts associated with global warming has resulted in deleterious impacts on forest productivity in Southwest China. Despite attempts to explore the response of vegetation to drought, less is known about forest’s resilience in response to drought in Southwest China. Here, the reduced resilience of the forest was found based on remotely sensed optical and microwave vegetation products. The spatial distribution and temporal variation of resilience-reduced forest were assessed using the standardized precipitation evapotranspiration index (SPEI) and vegetation optical depth (VOD). Our findings showed that 40–50% of the forest appeared to have abnormally low resilience approximately 6 months after the severe drought. The spatial distributions of abnormally low resilience had a good agreement with the regions affected by the 2009–2011 drought events. In particular, our results indicated that areas of afforestation were more susceptible to drought than natural forest, maybe due to the different water uptake strategy of the diverse root systems. Our findings highlight the vulnerability of afforestation areas to climate change, and recommend giving more attention to soil water availability.
... While climate plays a major role in shaping communities and species' distributions (e.g. Kraft and Ackerly 2010, Graham et al. 2012, Rowan et al. 2016, there are several unique geomorphological and hydrogeological characteristics of karst landscapes and complex bioticabiotic interactions that likely combine to generate high endemic biodiversity in karst forests (Goldscheider 2012, Bárány-Kevei and Kiss 2016, Phillips 2016. Karsts were also likely refuges for species during past glacial cycles because of cave shelters and heterogeneous, diverse microclimates (Soto-Centeno et al. 2015, Mammola andLeroy 2018). ...
Article
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Ecological niche models (ENMs) can project changes in species’ distributions under climate change and thus inform conservation efforts and further our understanding of patterns of change. Predictions of species’ distribution shifts under climate change in topographically and geologically complex landscapes, such as karst landforms, should be improved by better integration of non-climate abiotic variables, such as karst geology or habitat structure, into model projections. We built ENMs for one of the limestone langurs, a group of leaf monkeys adapted to forests on the Sino-Vietnamese limestone karst landform. We collected occurrence localities for François’ leaf monkeys (Trachypithecus francoisi) and thinned them to avoid sampling bias. We included as environmental parameters a global dataset for karst geology and 19 bioclimatic variables derived from monthly temperature and precipitation at 30 arc-second resolution. ENMs including karst geology and climatic variables outperformed and differed spatially from climate-only models. Across six future-climate scenario projections, the optimal karst+climate model differed from the best climate-only model and predicted more spatial overlap with karst in the future, a contraction in total area of suitable habitat by the 2070s, and a small loss in the amount of suitable habitat in existing conservation areas. This study shows the importance of considering other abiotic factors beyond climate in projections of suitable habitat under climate change for species in complex landscapes. Because our results show that karst and climate interact to explain the distribution of a karst-adapted species, the results also suggest that, under climate change, these interactions are likely to produce altered networks of species into novel biological communities. Finally, our results support the need for conservation of limestone habitats and cross-border collaboration to maintain refuges and movement connectivity for endangered species in the face of climate change.
... In karst landscapes of central Kentucky, Quercus muehlenbergii (chinkapin oak) is a biogeomorphic ecosystem engineer. The species is able to penetrate limestone joints and fissures, where it facilitates weathering and soil formation, resulting in soil-filled rock partings and thicker soils that are favorable for future establishment of trees in general and Quercus muehlenbergii in particular (Phillips, 2016). However, this form of ecosystem engineering by chinkapin oak and other trees is self-limited, once a sufficiently thick substrate has developed (Phillips, 2018b). ...
Article
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.
... The soil layer, when present, plays an important role as a buffer zone of water perturbations, as in most areas, the precipitation filtrates through the soil before reaching the subsurface aquifers (Williams 2008). Epikarstic soils are also hypothesised to have a huge impact on larger scale karst formation as the main source of acidity in subsurface waters (Williams 2008;Phillips 2016). ...
Article
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Soils play an important role in the ecosystem of karstic landscapes both as a buffer zone and as a source of acidity to belowground water. Although the microbiota of karstic soils is known to have a great effect on karstification processes , the activity and composition of these communities are largely unknown. This study gives a comparative analysis of soil microbial profiles from different parts of a doline located at Aggtelek, Hungary. The aim was to reveal the relationships between the vegetation type and genetic fingerprints and substrate utilisation (multi-SIR) profiles of the soil microbiota. Soil samples were collected in early and late springs along a transect in a doline covered with different types of vegetation. Genetic fingerprints of bacterial communities were examined by denaturing gradient gel electrophoresis (DGGE) based on the 16S rRNA gene, along with multi-SIR profiles of the microbial communities measured by the MicroResp method using 15 different carbon sources. Genetic fingerprinting indicated that vegetation cover had a strong effect on the composition of soil bacterial communities. Procrustean analysis showed only a weak connection between DGGE and multi-SIR profiles, probably due to the high functional redundancy of the communities. Seasonality had a significant effect on substrate usage, which can be an important factor to consider in future studies.
... Trunk basal diameter may be linked to root system size and depth in karst ecosystems where vertical and horizontal root extension is hampered by the thin rocky soils. Root penetration into the karst vadose zone to gain access to bedrock water or groundwater is probably a slow process that only occurs when roots encounter fissures in the weathered bedrock (or create them themselves through root bioengineering), the chance of which likely increases with plant size and age (Phillips, 2016(Phillips, , 2018. Positive cross-species association between drought-induced canopy defoliation at the end of the experimental rainfall exclusion period (relative to predrought canopy condition) and the hydrogen (b) and oxygen (a) isotope composition of stem water during severe drought (but when green leaves were still present) in the 11 target species. ...
Article
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Root access to bedrock water storage or groundwater is an important trait allowing plant survival in seasonally dry environments. However, the degree of coordination between water uptake depth, leaf-level water use efficiency (WUEi) and water potential in drought-prone plant communities is not well understood. We conducted a 135-day rainfall exclusion experiment in a subtropical karst ecosystem with thin skeletal soils to evaluate the responses of eleven co-occurring woody species of contrasting life forms and leaf habits to a severe drought during the wet growing season. Marked differences in xylem water isotopic composition during drought revealed distinct ecohydrological niche separation among species. The contrasting behavior of leaf water potential in coexisting species during drought was largely explained by differences in root access to deeper, temporally stable water sources. Smaller-diameter species with shallower water uptake, more negative water potentials and lower WUEi showed extensive drought-induced canopy defoliation and/or mortality. In contrast, larger-diameter species with deeper water uptake, higher leaf-level WUEi and more isohydric behavior survived drought with only moderate canopy defoliation. Severe water limitation imposes strong environmental filtering and/or selective pressures resulting in tight coordination between tree diameter, water uptake depth, iso/anisohydric behavior, WUEi and drought vulnerability in karst plant communities.
... Based on the literature, we can identify several potential biogeomorphic rolescategories of influencefor a given species in a given environment. Biogeomorphic ecosystem engineering is sometimes contingent on specific environmental conditions (Phillips, 2016) and may be self-limiting (Phillips, 2018). Further, species roles as ecosystem engineers and as keystone or non-keystone species are also often context-dependent (Mills et al., 1993;Power et al., 1996;Matthews et al., 2014). ...
Article
Biogeomorphic keystone species profoundly impact landscapes, such that their introduction or removal would cause fundamental changes in geomorphic systems. This paper explores the concept of biogeomorphic keystone species by examining the general vs. species‐specific biogeomorphic impacts (BGIs) of trees on a limestone bedrock‐controlled stream, Shawnee Run, in central Kentucky. Field investigation identified three strong BGIs: i) biogeomorphic pool formation via bioweathering; ii) root‐bank associated bioprotection; and iii) avulsion‐originated island development linked to bioprotection. This research evaluates these impacts in the context of keystone or other biogeomorphic roles. Field survey was conducted on nine stream reaches, each consisting of 10‐12 hydraulic units of riffle, pool and run. Results suggest that American sycamore (Platanus occidentalis) plays a keystone role by promoting development of ~42% of pools of the study area. While geomorphic pools are formed by fluvial process‐form linkages, these biogeomorphic pools are developed by sycamore root induced channel bed bioweathering. Only American sycamore and chinquapin oak (Quercus muehlenbergii) exhibited root‐bank development amongst 15 different species identified – and thus play a vital role in bank bioprotection. Lastly, trees can promote avulsion‐originated island formation by creating erosion‐resistant bioprotective patches. Mature trees (in terms of size), particularly large American sycamore and chinquapin oak, dominate Shawnee Run islands with a mean diameter at breast height (DBH) > 40 cm. However, other trees can provide comparable bioprotection, particularly at mature stages. Because its absence would result in fundamentally different stream morphology, sycamore can be considered a biogeomorphic keystone species in Shawnee Run.
... Other potential BIS related to carbonate weathering and erosion may also exist. For example, the dissolution of carbonate rocks in modern karst landscapes is strongly contributed to by organic acids and biogenic CO 2 (Phillips, 2016a). As such, there may be as yet unrecognised shifts in the frequency of palaeokarst surfaces within the SSR. ...
Article
Link to full text: https://authors.elsevier.com/a/1aZvW2weQf0BA .............................................................................................................................................................................................................................................................................................................................................................. The landscapes and seascapes of Earth’s surface provide the theatre for life, but to what extent did the actors build the stage? The role of life in the long-term shaping of the planetary surface needs to be understood to ascertain whether Earth is singular among known rocky planets, and to frame predictions of future changes to the biosphere. Modern geomorphic observations and modelling have made strides in this respect, but an under-utilized lens through which to interrogate these questions resides in the most complete tangible record of our planetary history: the sedimentary-stratigraphic record (SSR). The characteristics of the SSR have been frequently explained with reference to changes in boundary conditions such as relative sea level, climate, and tectonics. Yet despite the fact that the long-term accrual of the SSR was contemporaneous with the evolution of almost all domains of life on Earth, causal explanations related to biological activity have often been overlooked, particularly within siliciclastic strata. This paper explores evidence for the ways in which organisms have influenced the SSR throughout Earth history and emphasizes that further investigation can help lead us towards a mechanistic understanding of how the planetary surface has co-evolved with life. The practicality of discerning life signatures in the SSR is discussed by: 1) distinguishing biologically-dependent versus biologically-influenced sedimentary signatures; 2) emphasizing the importance of determining relative time-length scales of processes and demonstrating how different focal lengths of observation (individual geological outcrops and the complete SSR) can reveal different insights; and 3) promoting an awareness of issues of equifinality and underdetermination that may hinder the recognition of life signatures. Multiple instances of life signatures and their historic range within the SSR are reviewed, with examples covering siliciclastic, biogenic and chemogenic strata, and trigger organisms from across the spectrum of Earth’s extant and ancient life. With this novel perspective, the SSR is recognised as a dynamic archive that expands and complements the fossil and geochemical records that it hosts, rather than simply being a passive repository for them. The SSR is shown to be both the record and the result of long-term evolutionary synchrony between life and planetary surface processes.
... It is currently unknown how the roots influence moonmilk formation in these caves although the presence of root organic matter would be expected to be important to these microbial communities. Much more work needs to be done to understand potential "ecosystem engineering" in karst landscapes, in particular the likely interactions between plant roots and the microorganisms associated with them (Phillips, 2016). ...
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Caves in Quintana Roo, Mexico are known for spectacular calcite formations, blue water, and their significance in Mayan culture. A fascinating feature of these caves is the tree roots that emerge from ceilings, walls, and floors. Little is known about these incredible natural structures which form a key part of the ecosystem, linking to the forests above. This work documents and identifies the species that use this deep rooting strategy as well as expands our understanding of the relationships between the surface and subterranean and the implications for the management and conservation of these natural structures and their resources. Caves in Quintana Roo, Mexico are known for spectacular calcite formations, blue water, and their significance in Mayan culture. A fascinating feature of these caves is the tree roots that emerge from ceilings, walls, and floors. Little is known about these incredible natural structures which form a key part of the ecosystem, linking to the forests above. This work documents and identifies the species that use this deep rooting strategy as well as expands our understanding of the relationships between the surface and subterranean and the implications for the management and conservation of these natural structures and their resources.
... Karst catchments offer "distinctive hydrological pathways and landforms that arise from high rock solubility and well developed secondary (fracture) porosity" (Ford and Williams, 2007). These are further shaped by a range of climatological, biogeomorphological and biochemical controls (Phillips, 2016). For example, planes of weakness such as faults, fractures, and fissures are a necessary precursor, providing preferential flow pathways, and development of karstic landforms is highly rainfall dependent (Harmand et al., 2017). ...
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Human exposure to water contaminated with faeces is a leading cause of worldwide ill-health. Contaminated water can be transmitted rapidly in karst terrain as a result of the connectivity of surface and groundwater systems, high transmissivity of aquifers over large areas, and well-developed underground conduit systems. Faecal indicator organisms (FIOs) are the most widely-used indicator of faecal contamination and microbial water quality; however, the conceptualisation of FIO risk and associated sources, pathways, and survival dynamics of FIOs in karst landscapes requires a degree of modification from traditional conceptual models of FIO fate and transfer in non-karst systems. While a number of reviews have provided detailed accounts of the state-of-the-science concerning FIO dynamics in catchments, specific reference to the uniqueness of karst and its influence on FIO fate and transfer is a common omission. In response, we use a mixed methods approach of critical review combined with a quantitative survey of 372 residents of a typical karst catchment in the southwest China karst region (SWCKR) to identify emerging research needs in an area where much of the population lives in poverty and is groundwater dependent. We found that the key research needs are to understand: 1) overland and subsurface FIO export pathways in karst hydrology under varying flow conditions; 2) urban and agricultural sources and loading in mixed land-use paddy farming catchments; 3) FIO survival in paddy farming systems and environmental matrices in karst terrain; 4) sediment-FIO interactions and legacy risk in karst terrain; and 5) key needs for improved hydrological modelling and risk assessment in karst landscapes. Improved knowledge of these research themes will enable the development of evidence-based faecal contamination mitigation strategies for managing land and water resources in the SWCKR, which is highly vulnerable to climate change impacts on water supply and quality of water resources.
... The term biokarst has been coined to describe landscapes in which biological processes drive karstification, creating features on a range of scales (de la Rosa, 2016;Duane et al., 2003;Fiol et al., 1996;Viles, 1984). In one extreme, all karst may be considered biologically linked, as the evolution of photosynthetic life produced the carbonate rock necessary for karst formation, fundamentally linking the two processes in evolutionary time (Phillips, 2016a). However, biokarst generally refers to more recent feedbacks, such as heterogeneity in organic matter cycling (via primary production and respiration) or mechanical activities of plants or animals, which dramatically accelerate local weathering. ...
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We constructed mass balances of both calcium and phosphorus for two watersheds in Big Cypress National Preserve in southwest Florida (USA) to evaluate the time scales over which its striking landscape pattern developed. This low-relief carbonate landscape is dotted with evenly spaced, evenly sized, shallow surface depressions that annually fill with surface water and thus support wetland ecosystems (e.g. cypress domes) embedded in a pine-dominated upland matrix with exposed bedrock. Local and landscape scale feedbacks between hydrology, ecological dynamics and limestone dissolution are hypothesized to explain this karst dissolution patterning. This hypothesis requires the region to be wet enough to initiate surface water storage, which constrains landscape formation to interglacial periods. The time scale therefore would be relatively recent if creation of the observed pattern occurred in the current interglacial period (i.e. Holocene), and older time scales could reflect inherited patterns from previous inter-glacial periods, or from other processes of abiotic karstification. We determined phosphorus stocks across four landscape compartments and estimated the limestone void space (i.e., wetland depression volume) across the landscape to represent cumulative calcium export. We calculated fluxes in (e.g., atmospheric deposition) and out (i.e., solute export) of the landscape to determine landscape denudation rates through mass balance. Comparing stocks and annual fluxes yielded independent estimates of landscape age from the calcium and phosphorus budgets. Our mass balance results indicate that the landscape began to develop in the early-mid Holocene (12,000–5000 ybp). Radiocarbon dating estimates implied similar rates of dissolution (~1 m per 3000–3500 years), and were in agreement with Holocene origin. This supports the hypothesis that ecohydrologic feedbacks between hydrology and vegetation occurring during the present interglacial period are sufficient to shape this landscape into the patterns we see today, and more broadly suggests the potential importance of biota in the development of macro-scale karst features.
... Ecohydrologic interactions among climate, vegetation growth, and soil building and respiration can exert additional controls on weathering rates via organic acids and soil CO 2 production, which accelerate weathering by lowering pH (Berner, 1992;Drever, 1994). Estimates of the direct chemical effect of biota on weathering rate vary widely from minor (no more than a factor of 2) to an acceleration of two orders of magnitude (Drever, 1994;Bormann et al., 1998;Moulton and Berner, 1998;Phillips, 2016). In addition to their effect via acid supply, vegetation-climate interactions also influence soil water dynamics, a primary variable controlling CO 2 production, retention, and transport in soil (Moore and Knowles, 1989) and the development of soil cover (Kelly et al., 1998). ...
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Chemical weathering of bedrock plays an essential role in the formation and evolution of Earth's critical zone. Over geologic time, the negative feedback between temperature and chemical weathering rates contributes to the regulation of Earth climate. The challenge of understanding weathering rates and the resulting evolution of critical zone structures lies in complicated interactions and feedbacks among environmental variables, local ecohydrologic processes, and soil thickness, the relative importance of which remains unresolved. We investigate these interactions using a reactive-transport kinetics model, focusing on a low-relief, wetland-dominated karst landscape (Big Cypress National Preserve, South Florida, USA) as a case study. Across a broad range of environmental variables, model simulations highlight primary controls of climate and soil biological respiration, where soil thickness both supplies and limits transport of biologically derived acidity. Consequently, the weathering rate maximum occurs at intermediate soil thickness. The value of the maximum weathering rate and the precise soil thickness at which it occurs depend on several environmental variables, including precipitation regime, soil inundation, vegetation characteristics, and rate of groundwater drainage. Simulations for environmental conditions specific to Big Cypress suggest that wetland depressions in this landscape began to form around beginning of the Holocene with gradual dissolution of limestone bedrock and attendant soil development, highlighting large influence of age-varying soil thickness on weathering rates and consequent landscape development. While climatic variables are often considered most important for chemical weathering, our results indicate that soil thickness and biotic activity are equally important. Weathering rates reflect complex interactions among soil thickness, climate, and local hydrologic and biotic processes, which jointly shape the supply and delivery of chemical reactants, and the resulting trajectories of critical zone and karst landscape development.
... In terrestrial environments, ubiquitous erosive microbes and lichens create pits, exfoliations and other surface irregularities in rock (Viles 1995(Viles , 2012Chen et al. 2000). Even in caves, bats and bioerosive microbes create a complex topography of 'bell holes' and other textural features (Lundberg & McFarlane 2009;Phillips 2016). Smallscale and spatially limited bioerosive effects can result in larger scale changes if erosion is concentrated in critical locations (Naylor & Stephenson 2010), such as the joints between rocks or narrow bases of coral heads or in narrow bands in coastal rocks or marshes, causing undercutting and collapse (Figs S1-S4). ...
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Bioerosion, the breakdown of hard substrata by organisms, is a fundamental and widespread ecological process that can alter habitat structure, biodiversity and biogeochemical cycling. Bioerosion occurs in all biomes of the world from the ocean floor to arid deserts, and involves a wide diversity of taxa and mechanisms with varying ecological effects. Many abiotic and biotic factors affect bioerosion by acting on the bioeroder, substratum, or both. Bioerosion also has socio-economic impacts when objects of economic or cultural value such as coastal defences or monuments are damaged. We present a unifying definition and advance a conceptual framework for (a) examining the effects of bioerosion on natural systems and human infrastructure and (b) identifying and predicting the impacts of anthropogenic factors (e.g. climate change, eutrophication) on bioerosion. Bioerosion is responding to anthropogenic changes in multiple, complex ways with significant and wide-ranging effects across systems. Emerging data further underscore the importance of bioerosion, and need for mitigating its impacts, especially at the dynamic land–sea boundary. Generalised predictions remain challenging, due to context-dependent effects and nonlinear relationships that are poorly resolved. An integrative and interdisciplinary approach is needed to understand how future changes will alter bioerosion dynamics across biomes and taxa.
... Ł. Pawlik, P. Šamonil Earth-Science Reviews 178 (2018) 257-278 authors focusing on biotransport and bioturbations (Gabet et al., 2003;Field and Little, 2009;Hoffman and Anderson, 2013) (Fig. 21). In addition, microscale effects include soil deepening in treethrow pits caused by enhanced chemical weathering (Embleton-Hamann, 2004;Phillips et al., 2017) and soil deepening under tree stumps facilitated by biomechanical and biochemical weathering (Shouse and Phillips, 2016;Pawlik and Kasprzak, 2018). A different perspective has been proposed by the consideration of invasive species (Fei et al., 2014;e.g. ...
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Soil and regolith creep have been analyzed for at least the last 140 years, using many methodological configurations and temporal and spatial scales. The general concept of creeping soil and its mechanism, first proposed by W.M. Davis and G.K. Gilbert at the end of the 19th century, evolved since the 1940s towards theoretical models and precise short- and long-term field measurements. This fruitful epoch continued with results enhanced at the turn of the 20th century by the application of new research methods (e.g. radiometry) and a redefinition of the term soil creep to encompass the sum of stochastic shallow subsurface and near-surface processes causing net downslope movement of soil or regolith. Simultaneously, another possibility of creep detection was noticed in dendrochronology, and since the 1970s, in the formally defined discipline of dendrogeomorphology, indirect evaluations of creep activity were performed based on tree-ring analyses of bent trees. This method found many followers, but was also heavily criticized as imprecise and lacking in evidence of which kind of tree trunk curvature (e.g. “pistol-butt”- like deformation, S-shape curvature) could be ascribed to creep movement. From the beginning, soil creep was associated with the activity of living organisms on hillslopes. However, this aspect of creep studies has never been fully developed, in spite of the solid foundations and directions of potential studies pointed out by Charles Darwin at the end of the 19th century. In this paper we focus on the historical context of soil creep studies, and highlight forest ecosystems as probably the most active environment of biogenic creep, mainly due to tree uprooting and other biomechanical effects of living and dead trees (root channel infilling, tree root mounding etc.) that are a factors in biotransport. In the final sections the position of biogenic creep in the structure of biogeomorphic systems is discussed in relation to such important conceptual frameworks as the biogeomorphic ecosystem, biogeomorphic feedback window and ecosystem engineering. We also describe several hypotheses that should be carefully tested in the future, and propose several research methods that have the ability to further our knowledge about soil creep: radiometry, laser scanning and soil micromorphology.
... This has been called 'ecosystem engineering' (Jones et al., 1994;Gutiérrez and Jones, 2008;Corenblit et al., 2015). When this shaping affects geomorphic processes and landforms, the process has been called 'biogeomorphic ecosystem engineering' (Phillips, 2016) and resulting landforms are termed 'biogeomorphic structures' or units (Corenblit et al., 2010. They are usually made up by different landform components that can be of abiotic, residual or functional nature (Corenblit et al., 2010): Abiotic components are strictly created by physical processes, while residual components result from ecosystem engineering, but do not benefit the engineer. ...
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Vegetation is an important factor influencing solifluction processes, while at the same time, solifluction processes and landforms influence species composition, fine-scale distribution and corresponding ecosystem functioning. However, how feedbacks between plants and solifluction processes influence the development of turf-banked solifluction lobes (TBLs) and their geomorphic and vegetation patterns is still poorly understood. We addressed this knowledge gap in a detailed biogeomorphic investigation in the Turtmann glacier foreland (Switzerland). Methods employed include geomorphic and vegetation mapping, terrain assessment with unmanned aerial vehicle (UAV) and temperature logging. Results were subsequently integrated with knowledge from previous geomorphic and ecologic studies into a conceptual model. Our results show that geomorphic and vegetation patterns at TBLs are closely linked through the lobe elements tread, risers and ridge. A conceptual four-stage biogeomorphic model of TBL development with ecosystem engineering by the dwarf shrub Dryas octopetala as the dominant process can explain these interlinked patterns. Based on this model, we demonstrate that TBLs are biogeomorphic structures and follow a cyclic development, during which the role of their components for engineer and non-engineer species changes. Our study presents the first biogeomorphic model of TBL development and highlights the applicability and necessity of biogeomorphic approaches and research in periglacial environments.
... Importantly, the magnitude of these buffering effects was contingent on material properties such as porosity and thermal conductivity. These findings highlight the importance of 'rock control' in coastal weathering and erosion (Goudie, 2016;Naylor and Stephenson, 2010;Sunamura, 1994) and suggest that the occurrence, efficacy and rate of intertidal biogeomorphological processes (including bioprotection) are often contingent on rock type (e.g., Phillips, 2016). ...
Article
Sedentary and mobile organisms grow profusely on hard substrates within the coastal zone and contribute to the deterioration of coastal engineering structures and the geomorphic evolution of rocky shores by both enhancing and retarding weathering and erosion. There is a lack of quantitative evidence for the direction and magnitude of these effects. This study assesses the influence of globally-abundant intertidal organisms, barnacles, by measuring the response of limestone, granite and marine-grade concrete colonised with varying percentage covers of Chthamalus spp. under simulated, temperate intertidal conditions. Temperature regimes at 5 and 10 mm below the surface of each material demonstrated a consistent and statistically significant negative relationship between barnacle abundance and indicators of thermal breakdown. With a 95% cover of barnacles, subsurface peak temperatures were reduced by 1.59 °C for limestone, 5.54 °C for concrete and 5.97 °C for granite in comparison to no barnacle cover. The amplitudes of short-term (15–30 min) thermal fluctuations conducive to breakdown via 'fatigue' effects were also buffered by 0.70 °C in limestone, 1.50 °C in concrete and 1.63 °C in granite. Furthermore, concentrations of potentially damaging salt ions were consistently lower under barnacles in limestone and concrete. These results indicate that barnacles do not enhance, but likely reduce rates of mechanical breakdown on rock and concrete by buffering near-surface thermal cycling and reducing salt ion ingress. In these ways, we highlight the potential role of barnacles as agents of bioprotection. These findings support growing international efforts to enhance the ecological value of hard coastal structures by facilitating their colonisation (where appropriate) through design interventions.
... One characteristic of biogeomorphology as an area of study is the rapidity at which underpinning theory and concepts have developed. This includes important discussions devoted to scale-linkages (Phillips, 1995), complexity (Stallins, 2006), disturbance regimes (Viles et al., 2008) and contingency (Phillips, 2016a) among others. Perhaps most notably, the progressive integration of parallel ideas that emerged from the ecological and evolutionary sciences has done much to shape the way we think about what organisms 'do' in landscapes and, in-turn, how landform-and landscape-forming processes influence ecological functioning. ...
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Biogeomorphology is an umbrella term given to a highly-active research area within geomorphology that focusses on the many and varied interactions and feedbacks between organisms and the physical Earth. In the last 25?years this interest has developed and diversified to include the direct and indirect influences of microorganisms, plants, animals and humans on earth surface processes and landform dynamics, and the roles of geomorphology in ecological functioning, resilience and evolution. This Commentary introduces a virtual special issue of 16 research papers and 3 ?State of Science? pieces, illustrating the diversity of the field, its continued theoretical and conceptual progression, and the applied relevance of biogeomorphological science in tackling environmental problems. Collectively, these papers demonstrate the merits of?and opportunities for?biogeomorphology as an inherently integrative science in understanding and managing the complexity of living landscapes. This article is protected by copyright. All rights reserved.
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Abstract Ecosystem engineers strongly influence the communities in which they live by modifying habitats and altering resource availability. These biogenic changes can persist beyond the presence of the engineer, and such modifications are known as ecosystem engineering legacy effects. Although many authors recognize ecosystem engineering legacies, and some case studies quantify the effects of legacies, few general frameworks describe their causes and consequences across species or ecosystem types. Here, we synthesize evidence for ecosystem engineering legacies and describe how consideration of key traits of engineers improves understanding of which engineers are likely to leave persistent biogenic modifications. Our review demonstrates that engineering legacies are ubiquitous, with substantial effects on individuals, communities, and ecosystem processes. Attributes that may promote the persistence of influential legacies relate to an engineer's traits, including its body size, lifespan, and living strategy (individual, conspecific group, or collection of multiple co‐occurring species). Additional lines of inquiry, such as how the recipients respond (e.g., density or richness) or the mechanism of engineering (e.g., burrowing or structure building), should be included in future ecosystem engineering legacy research. Understanding patterns of these persistent effects of ecosystem engineers and evaluating the consequences of losing them is an important area of research needed for understanding long‐term ecological responses to global change and biodiversity loss.
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The complex web of interactions between ecological communities and the physical landscape (biogeomorphology) is being affected by the global scale environmental changes of the Anthropocene. Climate change, habitat destruction, invasions and extinctions are having profound impacts on biogeomorphological process regimes through changes in the composition and activity of ecological communities. However, on the other hand, deliberately-targeted human interventions to biogeomorphic systems have the potential to help mitigate against, and adapt to, the Anthropocene, by managing biogeomorphic processes to enhance resilience. To evaluate these relationships, we propose a conceptual framework based on the ecological concept of functional traits. We review how the Anthropocene is causing changes in species composition, abundance and the prevalence of functional traits to produce changes to biogeomorphic processes and functions that are, as yet, only partly understood. We use examples of fluvial, dryland and coastal biogeomorphic systems to illustrate how purposeful manipulation of biogeomorphic systems (as a type of Nature-based solution) can conserve, enhance or add biogeomorphic functions that are capable of enhancing geomorphic resilience. By focussing on function, this approach offers a range of advantages/avenues for biogeomorphological research. This includes the detection and prediction of human impacts, and an improved understanding of how biogeomorphology can contribute to tackling environmental challenges in the Anthropocene.
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The three-dimensional geoecosystem of karsts is very fragile, vulnerable, and it responds rather sensitively to any type of pollution, anthropogenic influence and also to direct and indirect effects of climate change. Population growth and therefore primarily the increasing agricultural demand, as well as the quarrying of carbonate rocks and mining of embedded minerals have become more important than the protection of these landscapes. Nowadays, these processes are studied in a complex way, both in space and time, by the interdisciplinary science of geoecology. The geoecological system of karsts is complex and diverse. It is a structural and dynamic system in which rock, water, soil, micro- and macroclimate constitute the abiogenic elements, while micro- and macroflora and fauna as well as people themselves constitute the biogenic elements. Our study presents the geoecological status of Hungarian karsts based on the evaluation of some geoecological parameters and some elements of their interaction.KeywordsKarst-geoecosystemClimate-soil-vegetation system of karstEcosystem serviceHungarian karsts
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The karst landform is a typical ecologically vulnerable region, and the problem of karst rocky desertification in southtern and western China has led to impoverishment and a degraded local ecological environment, which severely limits local socioeconomic development. An effective and appropriate control of karst rocky desertification in southtern and western China requires knowledge about its characteristics of variation and driving mechanisms. In this study, we chose eight regions in the southtern and western China as research areas and analysed the characteristics of the changes in karst ecosystem patterns and rocky desertification from 2000 to 2015. Based on these characteristics, we present the mechanisms that drive karst rocky desertification in the southtern and western China by utilizing the redundancy analysis (RDA) ordination method. The results show that the total area of rocky desertification in southtern and western China had been continuously decreasing from 2000 to 2015, revealing a positive development trend in rocky desertification. Rocky desertification variations were mainly affected by human activities. The reduction in farmland area improved farmland management and increased regional gross industrial product, which together with continuously rising gross domestic product of the tertiary industry caused a positive rocky desertification development. However, the local karst tourism has a certain effect on inducing slight rocky desertification. © 2021, Science Press, Northeast Institute of Geography and Agroecology, CAS and Springer-Verlag GmbH Germany, part of Springer Nature.
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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.
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Large wood (LW) is a ubiquitous feature in rivers of forested watersheds worldwide, and its importance for river diversity has been recognized for several decades. Although the role of LW in fluvial dynamics has been extensively documented, there is a need to better quantify the most significant components of LW budgets at the river scale. The purpose of our study was to quantify each component (input, accumulation, and output) of a LW budget at the reach and watershed scales for different time periods (i.e., a 50-year period, decadal cycle, and interannual cycle). The LW budget was quantified by measuring the volumes of LW inputs, accumulations, and outputs within river sections that were finally evacuated from the watershed. The study site included three unusually large but natural wood rafts in the delta of the Saint-Jean River (SJR; Québec, Canada) that have accumulated all LW exported from the watershed for the last fifty years. We observed an increase in fluvial dynamics since 2004, which led to larger LW recruitment and a greater LW volume trapped in the river corridor, suggesting that the system is not in equilibrium in terms of the wood budget but is rather recovering from previous human pressures as well as adjusting to hydroclimatic changes. The results reveal the large variability in the LW budget dynamics during the 50-year period and allow us to examine the eco-hydromorphological trajectory that highlights key variables (discharge, erosion rates, bar surface area, sinuosity, wood mobility, and wood retention). Knowledge on the dynamics of these variables improves our understanding of the historical and future trajectories of LW dynamics and fluvial dynamics in gravel-bed rivers. Extreme events (flood and ice-melt) significantly contribute to LW dynamics in the SJR river system.
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In the last decades, the research on ecosystem services have emerged in the field of geography. The negative impacts of human activities on the vulnerable karst areas are getting enforced quickly, which have an unfavourable influence on ecosystem service provision. On karstic areas, there are significant geographical processes, connected to biological activities. This issue is not adequately discussed in the current literature of karst ecology. In our study, we give an overview on the biogeomorphological feedbacks that change the functions and overall value of karst ecosystems. Furthermore, we also show two examples of recent landscape change processes and ecosystem service evaluations with this approach, from two karstic study areas in Hungary. Available from: https://www.researchgate.net/publication/311651381_OKOSZISZTEMA_SZOLGALTATASOK_ES_BIOGEOMORFOLOGIAI_VISSZACSA_TOLASOK_A_KARSZTOKON [accessed Mar 10 2021].
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The state of an Earth surface system (ESS) is determined by three sets of factors: Laws, place, and history. Laws (L = L1, L2, . . . , Ln) are the n general principles applicable to any such system at any time. Place factors (P = P1, P2, . . . , Pm) are the m relevant characteristics of the local or regional environment. History factors (H = H1 , H2, . . . , Hq) include the previous evolutionary pathway of the ESS, its stage of development, past disturbance, and initial conditions. Geoscience investigation may focus on laws, place, or history, but ultimately all three are necessary to understand and explain ESS. The LPH triad is useful as a pedagogical device, illustrated here via application to explaining the world's longest cave (Mammoth Cave, KY). Beyond providing a useful checklist, the LPH framework provides analytical traction to some difficult research problems. For example, studies of the avulsions of three southeast Texas rivers showed substantial differences in avulsion regimes and resulting alluvial morphology, despite the proximity and superficial similarity of the systems. Avulsions are governed by the same laws in all cases [L(A) = L(B) = L
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Although biogeomorphological research is well-established, with many studies on a range of two-way interrelations between organisms and geomorphology in different environments, there is little consensus over what constitutes biogeomorphology, why it might be useful and where it is heading. Starting with definitions of core biogeomorphic processes, we consider the need for future biogeomorphological studies to evaluate the crucial links between bioprocesses, biological community dynamics and ‘inorganic’ earth surface processes. Five key applications of biogeomorphological research are identified; the roles of organisms in environmental reconstruction, trace fossil analysis, extraterrestrial geomorphology, environmental engineering and the built environment. Some key research directions and methodological challenges for future biogeomorphological research include expanding the spatial and temporal coverage of datasets, investigating the role of bioprocesses in landform development, tackling scale issues, investigating the relevance of nonlinear dynamical ideas to biogeomorphology and developing better sampling and monitoring techniques for bioprocesses.
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Th e Aggtelek Karst Region was declared as a part of World Heritage on 2 December 1995. Since the formation of the Aggtelek National Park (1985) the measures taken to limit human activity have brought about some predictable improvement in maintaining a state close to the natural conditions. Th e karst depressions in Aggtelek are situated in various orographic, lithologic and tectonic situation. On this basis three main groups may be distinguished: dolines situa ted at the height 310-350 rn, 270-280 and around 500 m. Present paper per mitted to identify first of all the connection between the doline asymmetry and ecological processes. Karst dolines are environmentally very sensitive site point of the karst region. The climate and the microclimate play the most important role of doline development. The soil covering the karst-forming rock, through the a-biogeneous and biogeneous processes, controls the nature and the order of magnitude of the corrosion process. From this point view by the side of climate and microclimate the vegetation plays an important role in the intensity of corrosion. In Aggtelek we have found lot of degraded grass plots in dolines, where animal grazing used to be intensive. This paper presents some ecological factors and their effects on the development of doline morphology.
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Biotic influences on geomorphology (and vice-versa) are ubiquitous. This paper explores whether landforms may be extended (composite) phenotypes of biota, based on four criteria: process–form relationships between biota and landforms; evolutionary synchrony; selective pressure via ecosystem engineering and niche construction; and positive feedback benefitting the engineer organism(s). Coral reefs, peat bogs, biomantles, insect mounds, grassland soils, salt marshes, mangrove swamps, and some vegetation-dependent sand dune types clearly meet these criteria. Karst landforms, meandering rivers, and tree uprooting pit-mound systems meet the first three criteria, but positive feedback to engineer organisms has not been established. Research in biogeomorphology will surely identify other extended phenotypes. Implications are that biological evolution will continue to drive landscape metamorphosis, the appearance of new landform types, and presumably the disappearance of extended phenotypes associated with extinct species. Independently of extended phenotypes, tightly-coupled geomorphological–ecological interactions such as coevolution, and biogeomorphic forms of ecosystem engineering and niche construction are common. The troposphere, encompassing Earth’s landforms, is partly a biotic construct. Some elements would be present in an abiotic world, but the troposphere would not exist in anything resembling its contemporary state without a biosphere. This raises important questions with respect to Earth system evolution. The bio, litho-, atmo-, hydro-, topo-, and pedospheres coevolve at the global scale. Major biotic events have driven revolutions in the other spheres, but the atmosphere and the global hydrological system seem to have been relatively steady-state at the global scale. The toposphere and pedosphere have not. This suggests that perhaps landforms and soils provide the major mechanisms or degrees of freedom by which Earth responds to biological evolution. Landforms and soils may thus be the ‘voice’ of the biosphere as it authors planetary change, even if clear biotic signatures are lacking.
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In 1957 several eminent scientists ('the 1957 Blue Tier Expedition') investigated unusual rock markings reported to be Aboriginal petroglyphs on Blue Tier in northeast Tasmania and concluded that some markings were the result of dissolution of granite by roots, some were made by the subaerial action of plants abrading granite, and others were made by miners and prospectors. However a recent publication has restated claims of an Aboriginal origin for the 'petroglyphs'. As a result the markings were re-examined so that their genesis could be conclusively decided. The markings on Blue Tier are classified into eight types: (1) Rills; (2) Long Linear Grooves; (3) Circular Holes; (4) Inscriptions; (5) Oval Depressions; (6) Regularly Spaced Circular Depressions; (7) Short Linear Grooves; and (8) Small Circular Depressions. We conclude that Types 1, 2, 5, 7 and 8 markings are natural; Type 3 markings were drilled by prospectors or geologists; Type 4 markings were incised by miners or visitors; and Type 6 markings, which form a distinctive feature just below the crest of Australia Hill, were made by tin prospectors employed by the Mt Lyell Railway and Mining Company Limited. Therefore all markings on Blue Tier have been either produced by natural means (chiefly chemical weathering) or by geologists, prospectors and recent visitors. There is no evidence for the presence of Aboriginal petroglyphs on Blue Tier.
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The Karst Waters Institute Breakthroughs in Karst Geomicrobiology and Redox Geochemistry conference in 1994 was a watershed event in the history of cave geomicrobiology studies within the US. Since that time, studies of cave geomicrobiology have accelerated in number, complexity of techniques used, and depth of the results obtained. The field has moved from being sparse and largely descriptive in nature, to rich in experimental studies yielding fresh insights into the nature of microbe-mineral interactions in caves. To provide insight into the changing nature of cave geomicrobiology we have divided our review into research occurring before and after the Breakthroughs conference, and concentrated on secondary cave deposits: sulfur (sulfidic systems), iron and manganese (ferromanganese, a.k.a. corrosion residue deposits), nitrate (a.k.a. saltpeter), and carbonate compounds (speleothems and moonmilk deposits). The debate concerning the origin of saltpeter remains unresolved; progress has been made on identifying the roles of bacteria in sulfur cave ecosystems, including cavern enlargement through biogenic sulfuric acid; new evidence provides a model for the action of bacteria in forming some moonmilk deposits; combined geochemical and molecular phylogenetic studies suggest that some ferromanganese deposits are biogenic, the result of redox reactions; and evidence is accumulating that points to an active role for microorganisms in carbonate precipitation in speleothems.
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Progress in the understanding of speleogenetic processes, as well as the intensive research carried out in the Alps during the last decades, permit to summarise the latest knowledge about Alpine caves. The phreatic parts of cave systems develop close to the karst watertable, which depends on the spring position, which in turn is generally related to the valley bottom. Thus, caves are directly linked with the geomorphic evolution of the surface and reflect valley deepening. The sediments deposited in the caves help to reconstruct the morphologic succession and the paleoclimatic evolution. Moreover, they are the only means to date the caves and thus the landscape evolution. Caves appear as soon as there is an emersion of limestone from the sea and a watertable gradient. Mesozoic and early Tertiary paleokarsts within the Alpine range prove of these ancient emersions. Hydrothermal karst seems to be more wide-spread than previously presumed. This is mostly due to the fact that usually, hydrothermal caves are later reused (and reshaped) by meteoric waters. Rock-ghost weathering is described as a new speleogenetic agent. On the contrary, glaciers hinder speleogenetic processes and fill caves with sediment. They mainly influence speleogenesis indirectly by valley deepening and abrasion of the caprock. All present datings as well as morphological indications suggest that many Alpine caves (excluding paleokarst) are of Pliocene or even Miocene age. Progress in dating methods (mainly the recent evolution with cosmogenic nuclides) should permit, in the near future, to date not only Pleistocene, but also Pliocene cave sediments absolutely.
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A series of studies claimed that deep root development of plant established in karst regions was facilitated by fractured bedrock beneath the shallow soils; however, bedrock is not a uniform medium for root proliferation. We hypothesized plant species that survived in different karst habitats had some other rooting characteristics rather than deep penetration. To test the hypothesis, coarse root systems of two widely distributed woody species (one tree and one shrub) growing in three typical rocky karst habitats (shallow soil, loose rocky soil and exposed rock) were excavated in karst region of southwest China. Root systems were investigated based on four parameters: maximum rooting depth, maximum radial extent, root tapering pattern and root curvature. In all the three habitats, maximum rooting depths were no deeper than 120 and 40 cm for the tree and shrub species, respectively. Maximum radial extents were extremely large compared with maximum rooting depth, indicating that rooting characteristics were dominated by horizontal extension rather than deep penetration. Roots of both species growing in shallow soil habitat tapered gradually and curved slightly, which was consistent with the specific characteristics of this habitat. On the contrary, roots of the tree species growing in the other two habitats tapered rapidly but curved slightly, while roots of the shrub species tapered gradually but curved strongly. It was speculated that limited depths and rapid tapering rates of the tree roots were likely compensated by their utmost radial extensions, while the shrub species might benefit from its root curvature as the associated root tropisms may increase the ability of root to encounter more water and contribute to potentially high resource absorption efficiency. Our results highlight the importance of taking shallow-rooted species into account in understanding the distribution of natural plant communities and predicting future vegetation dynamics in karst regions.
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While niche construction theory locates animal artefacts in their constructors’ environment, hence treating them as capable of exerting selective pressure on both the constructors and their descendants, the extended phenotype concept assimilates artefacts with their constructors’ genes. Analogous contrasts apply in the case of endoparasite and brood parasite genes influencing host behaviour. The explanatory power of these competing approaches are assessed by re-examining the core chapters of Richard Dawkins’ The Extended Phenotype. Because animal artefacts (chapter 11) have multiple evolutionary consequences for their constructors, the extra-body effects of a gene seemingly include feedback effects on multiple other genes, a result which is more consistent with niche construction theory than with selfish gene theory. In the case of endoparasite genes influencing host behaviour (chapter 12), Dawkins’ argument leaves out what appears to be the key explanatory component, namely the role of the host’s own bodily systems in making it possible for such genes to exist. For action at a distance (chapter 13), it is unclear whether the key genes have extended effects because they sit in the body of the manipulating organism, or alternatively do not have such effects because they sit in the body of its victim. It is argued that niche construction theory offers a superior explanation in all three cases, regardless of whether the extended phenotype concept is interpreted in selfish gene or selfish organism terms.
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Rocky desertification, which is relatively less well known than desertification, refers to the processes and human activities that transform a karst area covered by vegetation and soil into a rocky landscape. It has occurred in various countries and regions, including the European Mediterranean and Dinaric Karst region of the Balkan Peninsula, Southwest China on a large scale, and alarmingly, even in tropical rainforests such as Haiti and Barbados, and has had tremendous negative impacts to the environment and social and economic conditions at local and regional scales. The goal of this paper is to provide a thorough review of the impacts, causes, and restoration measures of rocky desertification based on decades of studies in the southwest karst area of China and reviews of studies in Europe and other parts of the world. The low soil formation rate and high permeability of carbonate rocks create a fragile and vulnerable environment that is susceptible to deforestation and soil erosion. Other natural processes related to hydrology and ecology could exacerbate rocky desertification. However, disturbances from a wide variety of human activities are ultimately responsible for rocky desertification wherever it has occurred. This review shows reforestation can be successful in Southwest China and even in the Dinaric Karst region when the land, people, water, and other resources are managed cohesively. However, new challenges may arise as more frequent droughts and extreme floods induced by global climate change and variability may slow the recovery process or even expand rocky desertification. This review is intended to bring attention to this challenging issue and provide information needed to advance research and engineering practices to combat rocky desertification and to aid in sustainable development.
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Ecosystem engineers are organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. In so doing they modify, maintain and create habitats. Autogenic engineers (e.g. corals, or trees) change the environment via their own physical structures (i.e. their living and dead tissues). Allogenic engineers (e.g. woodpeckers, beavers) change the environment by transforming living or non-living materials from one physical state to another, via mechanical or other means. The direct provision of resources to other species, in the form of living or dead tissues is not engineering. Organisms act as engineers when they modulate the supply of a resource or resources other than themselves. We recognise and define five types of engineering and provide examples. Humans are allogenic engineers par excellence, and also mimic the behaviour of autogenic engineers, for example by constructing glasshouses. We explore related concepts including the notions of extended phenotypes and keystone species. Some (but not all) products of ecosystem engineering are extended phenotypes. Many (perhaps most) impacts of keystone species include not only trophic effects, but also engineers and engineering. Engineers differ in their impacts. The biggest effects are attributable to species with large per capita impacts, living at high densities, over large areas for a long time, giving rise to structures that persist for millennia and that modulate many resource flows (e.g. mima mounds created by fossorial rodents). The ephemeral nests constructed by small, passerine birds lie at the opposite end of this continuum. We provide a tentative research agenda for an exploration of the phenomenon of organisms as ecosystem engineers, and suggest that all habitats on earth support, and are influenced by, ecosystem engineers.
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The karstic area of São Domingos, central Brazil, holds extensive drainage systems. In order to understand its biodiversity, various volumes of water were filtered with planktonic nets in stretches of subterranean and superficial rivers on five different occasions. We sampled four drips (152L), three calcite pools (368L), two subterranean rivers fed mainly by percolation water (6,395L), two subterranean rivers fed mainly by water coming from a sinkhole (4,175L) along different caves, one resurgence (158L), and four epigean rivers (101,690L). Physical and chemical variables were measured at some sites. Canonical Correlation Analysis was used to verify relationships between taxa and environment. The degree of similarity of the biota was assessed by cluster analysis (Sorensen, single linkage). There were records of exclusive taxa in epi-gean and subterranean samples, mainly in drips, which harbour the most unique fauna. The high richness of taxa presently recorded reveals the potential of the vadose zone biota in the tropical region, which was neglected in studies on Brazilian subterranean biodiversity. According to our results, the unsaturated zone tropical fauna may have different composition compared to that from temperate habitats. The studied communities were dominated by rotifers, while crustacean are predominant in the latter. The hypothesis can be clarified with the increase of long term studies and taxa identification at species level, besides the use of complementary sampling methods.
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Background In this issue, Estrada-Medina and coworkers described the diversity of materials in the rhizosphere of the Yucatán karst, México, and quantified the distribution of roots across karst features. Scope This commentary explores the implications of their work for below-ground competition and the dynamics of plant-available water on seasonal to inter-annual timescales. Though details differ, seasonal dynamics of water use were consistent with a two-layer model, characterized by water uptake from shallow soil and rock layers during the wet season and deeper soil pockets and rock layers during the dry season. Soil pockets were more densely rooted than rock and experienced large fluctuations in soil moisture, suggesting intense below-ground competition. Total water storage capacity in the rhizosphere was far greater than actual storage in the year of the study. This raises the question whether some storage components in the karst rhizosphere fluctuate on time scales exceeding 1 year. Conclusions Despite the significant global extent of karst and their larger than proportional contribution to global biodiversity, vegetation models have ignored their unique rhizosphere structure. Differences in water storage could affect the responses of karst ecosystems and communities to climate change.
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Background and Aims With limited soil depth in northern Yucatán (<30 cm), roots grow deeper through rock fractures and dissolution karst features (i.e., cavities, including soil-filled ones known as soil pockets). We assessed the importance of limestone bedrock and dissolution karst features on tree root growth. Methods Fieldwork was conducted in a limestone quarry where the relative proportions of rock matrix, empty cavities, and soil pockets were calculated by observing recently exposed walls. Physical properties of rocks, topsoil, and soil pockets were analyzed. Root distribution was assessed and roots identified. Results Soil pockets represented 9% of the rock matrix. The physical properties of rock layers were different with depth. Available water capacity is higher in soil (0.11 m-3 m-3) than in rock layers (<0.05 m-3 m-3). But potential available water was much higher in subsurface features than top soil. Conclusions Dissolution karts features allow roots to grow deep into the bedrock, tapping water stored there. Although the limestone upper layer in northern Yucatan is highly restrictive to root growth, subsurface limestone layers and soil pockets are not restrictive and can hold important amounts of water.
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This book draws together the major recent advances in the modeling of karst systems. Based on the dissolution kinetics of limestone, and flow and transport processes in its fractures, it presents a hierarchy of cave genetic situations that range from the enlargement of a single fracture to the evolution of cavernous drainage patterns in confined and unconfined karst aquifers. These results are also applied to the evolution of leakage below dam sites in karst. The book offers a wealth of informations that help to understand the development of cave systems. It addresses geologists, hydrologists, geomorphologists, and geographers. It is also of interest to all scientists and engineers who have responsibilities for groundwater exploration and management in karst terrains.
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Restoration can be viewed as the process of reestablishing both exogenous drivers and internal feedbacks that maintain ecosystems in a desirable state. Correcting exogenous and abiotic drivers is clearly necessary, but may be insufficient to achieve desired outcomes in systems with self-organizing biotic feedbacks that substantially influence ecological stability and timing of responses. Evidence from a broad suite of systems demonstrates the prevalence of biotic control over key ecosystem attributes such as hydroperiod, nutrient gradients, and landform that are most commonly conceived of as exogenously controlled. While a general theory to predict conditions under which biotic controls exert such strong feedbacks is still nascent, it appears clear that the Greater Everglades/South Florida landscape has a high density of such effects. The authors focus on three examples of biotic control over abiotic processes: hydroperiod and discharge controls exerted by peat accretion in the ridge-slough landscape; phosphorus (P) gradients that emerge, at least in part, from interactions between accelerated peat accretion rates, vegetation structure and fauna; and reinforcing feedbacks among land elevation, aquatic respiration, and carbonate dissolution that produce local and landscape basin structure. The authors propose that the unifying theme of biogeomorphic landforms in South Florida is low extant topographic variability, which allows reciprocal biotic modification of local site conditions via mechanisms of peat accretion (including via effects of landscape P redistribution on primary production) or limestone dissolution. Coupling these local positive feedbacks, which drive patch expansion, with inhibitory or negative feedbacks on site suitability at distance, which serve to constrain patch expansion, provide the mechanistic basis for landscape pattern formation. The spatial attributes (range and isotropy) of the distal negative feedback, in particular, control pattern geometry; elucidating the mechanisms and properties of these distal feedbacks is critical to restoration planning.
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The global carbonate cycle has been controlled and maintained by life processes for at least 3.5 billion years. Within the exogenic carbonate cycle and in very different environments cyanobacteria appear in ‘key positions’ in that they actively and passively influence carbonate cycling. In the carbonate cycle, cyanobacteria play an important and sometimes decisive role. Cycling of carbon and carbonate is linked to biological processes. Some build up specific carbonate structures, some destroy carbonate substrates and others do both simultaneously. All these processes take place from the high mountains down to the sea in various terrestrial and freshwater as well as marine environments. The photosynthetic activity of cyanobacteria, their extracellular polymeric substances and possibly also their adherent heterotrophic bacteria are responsible for the construction of various carbonate structures and the ability to penetrate carbonate material. Boring activity of euendoliths results in biological corrosion and disintegration of carbonate surfaces. Grazing organisms on carbonate surfaces colonized by epi- and endolithic cyanobacteria produce specific biokarst forms and specific grains which can contribute to nearshore sedimentation. Biological corrosion and abrasion together constitute bioerosion. The results of all these processes are calcareous crusts, typical traces and biokarst forms which in many cases have a high fossilization potential, and therefore can be powerful ecological, palaeoecological and facies indicators in recent as well as in fossil environments.
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This book provides an extensive regional survey of palaeokarst, with emphasis on origin, significance and exploitation. It covers such features in numerous countries, mostly in the northern hemisphere. Part 1, the Introduction, is short and largely concerned with problems of different terminology in different countries. The second part (330 pages) is an extensive regional review of palaeokarst in various regions, including Belgium, Britain, Norway, Poland, Czechoslovakia, Hungary, Italy, Yugoslavia, USSR, Bulgaria, Canada, China, United States and elsewhere. The third part deals with mineral deposits associated with karst. The fourth part is on hydrogeology and engineering hazards in palaeokarst areas. Part 5 comprises four chapters mostly concerned with origin and biostratigraphic investigations in palaeokarst. Part 6 consists of four pages of conclusions. The final part has about 1000 references. -R.Foster
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This text book has four introductory chapters describing karst landforms and landscapes, a chapter on carbonate geochemistry and another on karst hydrology. The core of the book consists of four chapters on the chemistry of karst waters, the processes of sedimentary in-filling, the origin of caves, and the evolution of karst systems through geological time. There are two chapters on karst forms in evaporite rocks, and in granites and quartzites, and the final two chapters are on environmental problems of karst regions (land use and water quality). -K.Clayton
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Many studies of limestone coasts in the Tropics and sub-Tropics are concerned with intertidal form and process, neglecting the supra-tidal zone. Meso- and micromorphologies are described for a supratidal calcarenite coastal platform at Hells Gate, Lord Howe Island. Three morphological zones are identified and field and laboratory investigations elucidate their relation to process zonation. Pinnacles, similar to those described as phytokarst at other sub-tropical sites, are investigated and the role of biological processes in their formation is examined. Evidence for selective biodisintegration is presented. The pinnacles at Hells Gate cannot be described as phytokarst but have biokarstic properties. This study contributes to ongoing discussions on the role of biological weathering in coastal environments. © 2003 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart.
Chapter
What is Karst?What is a Cave?Where are the Deepest and Longest Caves?Caves as Geomorphic SystemsNow the Details …
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Half-Title PageWiley Series PageTitle PageCopyright PageTable of ContentsPreface and Acknowledgements
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Light oriented pinnacles (phytokarst) developed on the surface of limestone strata and boulders in cave entrances in Sarawak, are reported. These pinnacles are erosional forms produced by boring and, or, solutional action of red and blue-green algae which colonize the rock surfaces.-from Authors
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Interactions between organisms are a major determinant of the distribution and abundance of species. Ecology textbooks (e.g., Ricklefs 1984, Krebs 1985, Begon et al. 1990) summarise these important interactions as intra- and interspecific competition for abiotic and biotic resources, predation, parasitism and mutualism. Conspicuously lacking from the list of key processes in most text books is the role that many organisms play in the creation, modification and maintenance of habitats. These activities do not involve direct trophic interactions between species, but they are nevertheless important and common. The ecological literature is rich in examples of habitat modification by organisms, some of which have been extensively studied (e.g. Thayer 1979, Naiman et al. 1988).
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This paper considers the contributions of epigenic karst processes as a major element of the carbon cycle and a significant agent of landscape evolution. Geochemical models developed from monitoring data and water samples are used to estimate the variation and magnitude of DIC flux in karst landscapes at several scales, from local to global. At the local scale, the Cumberland River watershed of southeast Kentucky, these geochemical models are also used to evaluate the potential role of sulfur in the production of DIC and to compute an estimated rate of landscape erosion.Geochemical modeling using ionic species and modeled discharge reveal a variable rate of DIC flux driven by large fluctuations in calcite saturation and discharge. Ratios of reaction products and PCA analyses suggest that some bedrock dissolution may be driven by the oxidation of reduced sulfur derived from brines entrained into the karst aquifers. Over the 3,730 km2 of carbonate exposure in the Cumberland River, 25.8–62.4 Gg/yr of CO2 is conveyed from the atmosphere through the dissolution of carbonate. At the global scale, this translates to 123–296 Tg/yr of CO2 delivered by karst processes into the aqueous system.The bedrock portion of DIC equates to a flux of 32.6±2.6 m3 – 35.2±2.8 m3 of bedrock during the period of study of which 29% was dolomite. This translates to a landscape erosion rate of 13.1–17.9 mm/ka in the 3.45–4.32 km2 of carbonate exposure in the studied watershed. Based upon 16+ km of cave survey data spanning a vertical range of 72–75 m above base level, this suggests that cave development in the watershed spans the Plio-Pleistocene. Using the modeled erosion rates, the ages of cave levels, 4.03–5.71, 3.08–4.56, 1.57–2.43, 1.01–1.67, 0.45–0.91, and <0.45 Ma, are in good agreement with regional studies of Plio-Pleistocene landscape evolution in the Appalachian Lowland Plateaus. This article is protected by copyright. All rights reserved.
Article
Chemical activity is confined almost entirely to the vegetation and soil and to the bedrock directly in contact with soil or plant roots, and comparatively little chemical erosion occurs within the main body of limestone. Thus, in the case of Ca and Mg, not only is the rate of uptake of these elements by the forest of the same magnitude as groundwater losses (range 600-729 kg ha-1 yr-1), but much of the output from the outcrops is derived from the soil or soil-rock interface. Potassium is cycled particularly tightly, and net losses from the soil-vegetation system are negligible. -from Author
Article
Karst caves are unique biogeomorphological systems. Cave walls offer habitat for microorganismswhich in-turn have a geomorphological role via their involvement in rock weathering, erosion and mineralisation. The attenuation of light with distance into caves is known to affect ecology, but the implications of this for biogeomorphological processes and forms have seldom been examined. Here we describe a semi-quantitative microscopy study comparing the extent, structure, and thickness of biocover and depth of endolithic penetration for samples of rock from the Puerto Princesa Underground River system in Palawan, the Philippines, which is a natural UNESCOWorld Heritage Site. Organic growth at the entrance of the cave was abundant (100% occurrence) and complex, dominated by phototrophic organisms (green microalgae, diatoms, cyanobacteria, mosses and lichens). Thickness of this layer was 0.28 ± 0.18 mm with active endolith penetration into the limestone (mean depth = 0.13 ± 0.03 mm). In contrast, phototrophs were rare 50 m into the cave and biofilm cover was significantly thinner (0.01 ± 0.01 mm, p b 0.000) and spatially patchy (33% occurrence). Endolithic penetration here was also shallower (b0.01mm, p b 0.000) and non-uniform. Biofilm was found 250 m into the cave, but with a complete absence of phototrophs and no evidence of endolithic bioerosion. We attribute these findings to light-induced stress gradients, showing that the influence of light on phototroph abundance has knock-on consequences for the development of limestone morphological features. In marine caves this includes notches, which were most well-developed at the sheltered cave entrance of our study site, and for which variability in formation rates between locations is currently poorly understood.
Article
Patterned landscapes are often evidence of biotic control on geomorphic processes, emerging in response to coupled ecosystem processes acting at different spatial scales. Self-reinforcing processes at local scales expand patches, while self-inhibiting processes, operating at a distance, impose limits to expansion. In Big Cypress National Preserve (BICY) in southwest Florida, isolated forested wetland depressions (cypress domes) appear to be evenly distributed within a mosaic of short-hydroperiod marshes and pine uplands. To test the hypothesis that the apparent patterning is regular, we characterized frequency distributions and spatial patterns of vegetation communities, surface and bedrock elevation, and soil properties (thickness and phosphorus content). Nearest neighbor distances indicate strongly significant wetland spatial overdispersion, and bedrock elevations exhibited periodic spatial autocorrelation; both observations are consistent with regular patterning. Bedrock elevations and soil P were clearly bimodal, suggesting strong positive feedbacks on wetland patch development. Soil-surface elevations exhibited weaker bimodality, indicating smoothing of surface morphology by some combination of sediment transport, mineral reprecipitation, and organic matter production. Significant negative autocorrelation of bedrock elevations at scales similar to wetland spacing suggest the presence of distal negative feedbacks on patch expansion. These findings support the inference of regular patterning, and are consistent with the presence of local positive feedbacks among hydroperiod, vegetation productivity and bedrock dissolution. These processes are ultimately constrained by distal negative feedbacks, potentially induced by landscape scale limitations on the water volume required to enable this biogeomorphic mechanism. This article is protected by copyright. All rights reserved.
Article
All living organisms modify their biotic and abiotic environment. Niche construction theory posits that organism-mediated modifications to the environment can change selection pressures and in consequence the evolutionary trajectories of natural populations. While there is broad support for this proposition in general, there is considerable uncertainty about how niche construction is related to other similar concepts in ecology and evolution. Comparative studies dealing with certain aspects of niche construction are increasingly common, but there is a troubling lack of experimental tests of the core concepts of niche construction theory. Here, we propose an operational framework to evaluate comparative and experimental evidence of the evolutionary consequences of niche construction, and suggest how such research can improve our understanding of ecological and evolutionary dynamics in ecosystems. We advocate for a shift toward explicit experimental tests of how organism-mediated environmental change can influence the selection pressures underlying evolutionary responses, as well as targeted field-based comparative research to identify the mode of evolution by niche construction and assess its importance in natural populations.