Christopher M. Swan

Christopher M. Swan
University of Maryland, Baltimore County | UMBC · Department of Geography and Environmental Systems

PhD

About

129
Publications
65,570
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
9,007
Citations
Additional affiliations
January 1995 - May 2003
University of Maryland, College Park
Position
  • Research Assistant
August 2003 - September 2015
University of Maryland, Baltimore County
Position
  • Professor
Education
January 1998 - May 2003
January 1995 - December 1997
September 1992 - December 1994
West Chester University
Field of study
  • Biology

Publications

Publications (129)
Article
Full-text available
The relationship between biodiversity and stability, or its inverse, temporal variability, is multidimensional and complex. Temporal variability in aggregate properties, like total biomass or abundance, is typically lower in communities with higher species diversity (i.e., the diversity–stability relationship [DSR]). At broader spatial extents, reg...
Article
While how taxonomic diversity mediates changes in ecosystem function is well‐studied, how deeper dimensions of biodiversity drive important processes is understudied. The overarching goal of this work was to determine the role of these dimensions of biodiversity independently and/or interactively in explaining carbon processing in rivers. Here, we...
Article
Full-text available
Despite a growing literature-base devoted to document biodiversity patterns in cities, little is known about the processes that influence these patterns, and whether they are consistent over time. In particular, numerous studies have identified the capacity of cities to host a rich diversity of plant species. This trend, however, is driven primaril...
Article
The harsh geophysical template characterized by the urban environment combined with people’s choices has led ecologists to invoke environmental filtering as the main ecological phenomena explaining urban biodiversity patterns. Yet, dispersal is often overlooked as a driving factor, especially on expanding vacant land. Does overcoming dispersal limi...
Preprint
Full-text available
The relationship between biodiversity and stability, or its inverse, temporal variability, is multidimensional and complex. Temporal variability in aggregate properties, like total biomass or abundance, is typically lower in communities with higher species diversity (i.e., the diversity-stability relationship or DSR). Recent work has shown that, at...
Article
Habitat alteration and destruction are primary drivers of biodiversity loss. However, the evolutionary dimensions of biodiversity loss remain largely unexplored in many systems. For example, little is known about how habitat alteration/loss can lead to phylogenetic deconstruction of ecological assemblages at the local level. That is, while species...
Article
Full-text available
There is increasing interest in measuring ecological stability to understand how communities and ecosystems respond to broad-scale global changes. One of the most common approaches is to quantify the variation through time in community or ecosystem aggregate attributes (e.g. total biomass), referred to as aggregate variability. It is now widely rec...
Article
Full-text available
River managers strive to use the best available science to sustain biodiversity and ecosystem function. To achieve this goal requires consideration of processes at different scales. Metacommunity theory describes how multiple species from different communities potentially interact with local‐scale environmental drivers to influence population dynam...
Article
Full-text available
In cities, humans directly and indirectly affect plant and wildlife communities. These human–species interactions are not included in traditional ecological approaches used to understand why and how organisms are distributed. Here, we incorporate human behaviors into urban community assembly theories and detail all the complex ways humans affect th...
Article
Full-text available
Whether cities are more or less diverse than surrounding environments, and the extent to which non-native species in cities impact regional species pools, remain two fundamental yet unanswered questions in urban ecology. Here we offer a unifying framework for understanding the mechanisms that generate biodiversity patterns across taxonomic groups a...
Chapter
The main factors influencing litter decomposition in streams are substrate quality, metazoan feeding, microbial activity and environmental context. However, the biodiversity of both resources (litter) and consumers (mostly detritivorous invertebrates) can also influence decomposition, with consequences for stream ecosystem functioning. With regard...
Chapter
The decomposition of plant litter of terrestrial origin is a key process for the functioning of many stream ecosystems with notable relevance for global biogeochemical cycles. The process has received much attention in the literature but, since the iconic paper of Kaushik and Hynes (1971), we lack a comprehensive review of its patterns of variation...
Article
Full-text available
Cultivated exotic plants are often introduced for their aesthetic value and today comprise a substantial fraction of the flora of urban domestic gardens. Yet, their relative contribution to the functional diversity of domestic gardens and how it changes across different climate zones is insufficiently understood. Here, we investigated whether the e...
Preprint
Full-text available
It is well recognized that within local communities, fluctuations of constituent species over time can alter both aggregate (e.g., total abundance or biomass) and compositional community properties. At broader spatial scales, recent evidence shows how spatial asynchrony can further stabilize aggregate properties at the regional, or metacommunity, s...
Article
Full-text available
Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low a...
Article
Full-text available
Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low a...
Article
Full-text available
High nighttime urban air temperatures increase health risks and economic vulnerability of people globally. While recent studies have highlighted nighttime heat mitigation effects of urban vegetation, the magnitude and variability of vegetation-derived urban nighttime cooling differs greatly among cities. We hypothesize that urban vegetation-derived...
Article
Full-text available
Global loss of biodiversity and its associated ecosystem services is occurring at an alarming rate and is predicted to accelerate in the future. Metacommunity theory provides a framework to investigate multi-scale processes that drive change in biodiversity across space and time. Short-term ecological studies across space have progressed our unders...
Article
Full-text available
Context Ecological communities in urban ecosystems are assembled through ecological processes, such as species interactions, dispersal, and environmental filtering, but also through human factors that create and modify the landscape. These complex interactions make it difficult to untangle the relationships between social–ecological dynamics and ur...
Book
With almost 90% of terrestrial plant material entering the detrital pool, the processing of this significant carbon source is a critical ecosystem function to understand. Riverine ecosystems are estimated to receive, process and transport nearly 1.9 Pg of terrestrial carbon per year globally, highlighting the focus many freshwater ecologists have o...
Article
Full-text available
Recreational urban parks support diverse assemblages of plants that through their functions, contribute beneficial services to billions of individuals throughout the world. Drivers of vegetation-derived services in parks are complex, as climate and park management interact with the functioning of multiple species of vegetation types. Yet, informal...
Article
It is hypothesized that biodiversity is maintained by interactions at local and regional spatial scales. Many sustainability plans and management practices reflect the need to conserve biodiversity, yet once these plans are implemented, the ecological consequences are not well understood. By learning how management practices affect local environmen...
Chapter
Many stream invertebrates consume substantial amounts of plant litter at some time during their life cycle and thus play a key role in plant litter decomposition. These litter-consuming invertebrates include mainly shredders, a functional feeding group defined by their ability to shred litter, but also some scrapers, leaf miners, wood borers, and g...
Article
Full-text available
Urbanisation is driving rapid declines in species richness and abundance worldwide, but the general implications for ecosystem function and services remain poorly understood. Here, we integrate global data on bird communities with comprehensive information on traits associated with ecological processes to show that assemblages in highly urbanised e...
Article
Full-text available
The Earth's population will become more than 80% urban during this century. This threshold is often regarded as sufficient justification for pursuing urban ecology. However, pursuit has primarily focused on building empirical richness, and urban ecology theory is rarely discussed. The Baltimore Ecosystem Study (BES) has been grounded in theory sinc...
Article
Full-text available
Mounting evidence indicates that the inclusion of intraspecific trait variability (ITV) can strengthen the signal of trait-environment relationships, as well as provide insights into the eco-evolutionary strategies that allow species to establish and persist in different environments. Such information is particularly valuable in urban systems where...
Article
Full-text available
Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation,...
Article
Full-text available
Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation,...
Article
Global patterns of biodiversity have emerged for soil microorganisms, plants and animals, and the extraordinary significance of microbial functions in ecosystems is also well established. Virtually unknown, however, are large-scale patterns of microbial diversity in freshwaters, although these aquatic ecosystems are hotspots of biodiversity and bio...
Article
Full-text available
River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to...
Article
Full-text available
River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to...
Article
Full-text available
River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to...
Article
Full-text available
River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to...
Article
As urban areas continue expanding, major cities become connected forming megacities. Urban encroachment into natural areas transforms the landscape into a built environment with heterogeneously distributed patches of novel habitat. Community structure within novel habitats is influenced by anthropogenic factors including fragmentation and species i...
Article
Full-text available
Plant litter represents a major basal resource in streams, where its decomposition is partly regulated by litter traits. Litter-trait variation may determine the latitudinal gradient in decomposition in streams, which is mainly microbial in the tropics and detritivore-mediated at high latitudes. However, this hypothesis remains untested, as we lack...
Article
Full-text available
1. Ecological communities are structured by a combination of local processes like habitat filtering and species interactions, and regional forces driven by the dispersal of organisms between localities on a landscape. Previous studies suggest that the position of local communities within a dispersal network can greatly influence the relative influe...
Article
Full-text available
An often-cited benefit of river restoration is an increase in biodiversity or shift in composition to more desirable taxa. Yet, hard manipulations of habitat structure often fail to elicit a significant response in terms of biodiversity patterns. In contrast to conventional wisdom, the dispersal of organisms may have as large an influence on biodiv...
Article
Full-text available
Ecologists have long been interested in mechanisms governing community composition and assembly. Spatial connectivity is one potential mechanism that can have a large influence on community processes. In accordance with network metrics such as closeness and betweenness, headwater streams are more isolated than mainstem streams. Theory and observati...
Article
Full-text available
Despite high levels of disturbance and habitat modification, urban ecosystems still host substantial levels of biodiversity. The processes that maintain existing levels of diversity, however, remain understudied. Identifying the links between urban ecological processes and patterns has, therefore, become a fundamental research goal to support urban...
Article
Full-text available
Urban areas are understood to be extraordinarily spatially heterogeneous. Spatial heterogeneity, and its causes, consequences, and changes, are central to ecological science. The social sciences and urban design and planning professions also include spatial heterogeneity as a key concern. However, urban ecology, as a pursuit that integrates across...
Article
Full-text available
Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivor...
Article
Questions Urban ecosystems present an opportunity to study ecological communities in the context of unprecedented environmental change. In the face of urban land conversion, ecologists observe new patterns of species composition, dominance, behaviour and dispersal. We propose a hypothetical socioeconomic template that describes a gradient in human...
Article
Full-text available
1. Deconstructing biological communities by grouping species according to their commonness or rarity might improve our understanding about the processes driving variation in biological communities. Such an approach considers differences among organisms and emergent ecological patterns. 2. In this study, we addressed the relative role of spatial and...
Article
Odonates are suggested as bioindicators of human impact. However, their complex life cycles add additional challenges in the practical use as bioindicators, because the level of taxonomic identification could be dependent on life-history stage and, during their ontogeny, dramatic changes occur in their niche (ontogenetic niche shifts). Considering...
Article
Riparian forest plantings are a well-established restoration technique commonly used to stabilize banks and intercept nutrient flow from adjacent agricultural fields. Tree species planted for these efforts may not reflect mature forest communities within the same region. Given contemporary research on links between biodiversity and ecosystem functi...
Article
Community assembly and the resulting community structure reflect both local and regional processes. The relative importance, however, of each of these scales in most restoration contexts is unknown. Urban stream restoration, which often involves complete remodeling and replanting of the riparian zone, presents an opportunity to investigate the infl...
Article
Understanding what mechanisms shape the diversity and composition of biological assemblages across broad-scale gradients is central to ecology. Litter-consuming detritivorous invertebrates in streams show an unusual diversity gradient, with α-diversity increasing towards high latitudes but no trend in γ-diversity. We hypothesized this pattern to be...
Article
Full-text available
The biological, ecological, and evolutionary significance of serpentine habitats has long been recognised. We used an integrated physiochemical dataset combining plot spatial data with temporal data from tree cores to evaluate changes in soils and vegetation. Data suggest that this unique habitat is undergoing a transition, endangering local biodiv...
Article
Full-text available
Spatial heterogeneity of soil conditions combined with intraspecific variation confer site-specific edaphic tolerance, resulting in local adaptation and speciation. To understand the geoecological processes controlling community assembly of woodland tree species on serpentine and mafic soils, we investigated resource gradients and provenance (geogr...
Article
We assessed the effects of rising temperature and presence of a dominant detritivore (Allogamus laureatus; Trichoptera, Limnephilidae) on the decomposition of submerged oak litter (Quercus robur L.) and associated detritivore and fungal communities in a mountain stream in central Portugal. It was divided longitudinally, with one half maintained at...
Article
Understanding what mechanisms shape the diversity and composition of biological assemblages across broad-scale gradients is central to ecology. Litter-consuming detritivorous invertebrates in streams show an unusual diversity gradient, with α-diversity increasing towards high latitudes but no trend in γ-diversity. We hypothesized this pattern to be...
Chapter
In terrestrial systems, plants are the base of the food web, and their population growth is generally limited by resource availability rather than by higher trophic levels. Plants are also important components of the biogeochemical cycles that drive the movement of energy and resources. As primary producers, plants make energy available to higher t...
Article
Full-text available
Dispersal of organisms connects physical localities, but the strength of connection varies widely. Variability in the influence of dispersal can be predictable in sharply defined networks like river systems because some sections of the network are more isolated, leading to different balances of local (i.e. environmental filtering, species interacti...
Article
Full-text available
Freshwater salinization is an emerging environmental filter in urban aquatic ecosystems that receive chloride road salt runoff from vast expanses of impervious surface cover. Our study was designed to evaluate the effects of chloride contamination on urban stormwater pond food webs through changes in zooplankton community composition as well as den...
Article
Riparian ecosystems support mosaics of terrestrial and aquatic plant species that enhance regional biodiversity and provide important ecosystem services to humans. Species composition and the distribution of functional traits – traits that define species in terms of their ecological roles – within riparian plant communities are rapidly changing in...
Conference Paper
Background/Question/Methods Metacommunity theory explains diversity by simultaneously considering local forces (species interactions and local environment), and regional forces that are the products of dispersal, and all local communities are structured by some combination of those forces. When a metacommunity is located within a strongly delineat...
Conference Paper
Full-text available
Questions Patterns of functional and phylogenetic homogenization of plant diversity at the scale of entire cities are well established. However, fewer studies have investigated how shifts in the composition of urban species pools may alter spatial variation in community assembly across patches within a city. We compared plant diversity both within...
Article
Road deicers have been identified as potential stressors in aquatic habitats throughout the United States, but we know little regarding associated impacts to ecosystem function. A critical component of ecosystem function that has not previously been evaluated with respect to freshwater salinization is the impact on organic matter breakdown. The pur...
Conference Paper
Full-text available
Background / Purpose: One goal of sustainability plans in urban environments is to maintain or improve biodiversity. We contend that basic ecological theory can and should be revised to understand how biodiversity is maintained at multiple scales in urban ecosystems. We offer empirical support for a new conceptual model to understand the multi-sc...