Matthew E. Hopton

A simplified ecological footprint at a regional scale

We calculated an Ecological Footprint Analysis (EFA) at a regional scale. EFA captures the human impact on the environmental system by identifying the amount of biologically productive land necessary to support a persons level of consumption and waste generation. EFA is a commonly used metric of sustainability because it is easy to conceptualize and the calculation is relatively straightforward. Utilizing free, readily available data, we calculated an EFA for a region in southern Colorado. Gathering existing data at a regional scale is difficult because data are often collected at national or state levels. The lack of data is further confounded by the fact that data are often collected at intervals greater than one year. Variables that were missing data for certain years were estimated using linear interpolation. Data not available by county were scaled to the region from state or national level data. Thirty-five variables from 1980 to 2005 (26 years) were collected and used to calculate a time-dependent EFA and the resulting trend was visually examined. The available biocapacity in the region did not decrease during the period, but per capita biocapacity decreased due to population growth. Per capita biocapacity was at a period high of nearly 41 ha per person (ha/ca) in 1980 and steadily decreased to a low around 31 ha/ca in 2005. Ecological footprint remained constant over the 26-year period, varying from a low of 5.1 ha/ca in 1997 to a high of 5.5 ha/ca in 1985. A steady ecological footprint combined with a decreasing per capita biocapacity, implies the ecological reserve is decreasing and, thus, the region is moving away from sustainability. Although per capita consumption did not increase substantially during the 26 years, more people are drawing on a fixed quantity of resources. Our methodology is a simplified approach to EFA and does not follow standards that are currently being established. Adhering to the suggested standards would require obtaining data sets that consist entirely of national data. The national level data are replaced with data specific to the geographic area under examination when they are available. Although national data may represent the sub-national region under study, that substitution requires further investigation, especially in large, geographically and culturally varied nations such as the US. Nevertheless, this simplified methodology provides enough detail that stakeholders can identify areas of the system on which to focus attention to improve sustainability of the system.

How Much Is Enough? Minimal Responses of Water Quality and Stream Biota to Partial Retrofit Stormwater Management in a Suburban Neighborhood

Decentralized stormwater management approaches (e.g., biofiltration swales, pervious pavement, green roofs, rain gardens) that capture, detain, infiltrate, and filter runoff are now commonly used to minimize the impacts of stormwater runoff from impervious surfaces on aquatic ecosystems. However, there is little research on the effectiveness of retrofit, parcel-scale stormwater management practices for improving downstream aquatic ecosystem health. A reverse auction was used to encourage homeowners to mitigate stormwater on their property within the suburban, 1.8 km2 Shepherd Creek catchment in Cincinnati, Ohio (USA). In 2007–2008, 165 rain barrels and 81 rain gardens were installed on 30% of the properties in four experimental (treatment) subcatchments, and two additional subcatchments were maintained as controls. At the base of the subcatchments, we sampled monthly baseflow water quality, and seasonal (5×/year) physical habitat, periphyton assemblages, and macroinvertebrate assemblages in the streams for the three years before and after treatment implementation. Given the minor reductions in directly connected impervious area from the rain barrel installations (11.6% to 10.4% in the most impaired subcatchment) and high total impervious levels (13.1% to 19.9% in experimental subcatchments), we expected minor or no responses of water quality and biota to stormwater management. There were trends of increased conductivity, iron, and sulfate for control sites, but no such contemporaneous trends for experimental sites. The minor effects of treatment on streamflow volume and water quality did not translate into changes in biotic health, and the few periphyton and macroinvertebrate responses could be explained by factors not associated with the treatment (e.g., vegetation clearing, drought conditions). Improvement of overall stream health is unlikely without additional treatment of major impervious surfaces (including roads, apartment buildings, and parking lots). Further research is needed to define the minimum effect threshold and restoration trajectories for retrofitting catchments to improve the health of stream ecosystems.

The role of trees in urban stormwater management

Urban impervious surfaces convert precipitation to stormwater runoff, which causes water quality and quantity problems. While traditional stormwater management has relied on gray infrastructure such as piped conveyances to collect and convey stormwater to wastewater treatment facilities or into surface waters, cities are exploring green infrastructure to manage stormwater at its source. Decentralized green infrastructure leverages the capabilities of soil and vegetation to infiltrate, redistribute, and otherwise store stormwater volume, with the potential to realize ancillary environmental, social, and economic benefits. To date, green infrastructure science and practice have largely focused on infiltration-based technologies that include rain gardens, bioswales, and permeable pavements. However, a narrow focus on infiltration overlooks other losses from the hydrologic cycle, and we propose that arboriculture - the cultivation of trees and other woody plants - deserves additional consideration as a stormwater control measure. Trees interact with the urban hydrologic cycle by intercepting incoming precipitation, removing water from the soil via transpiration, enhancing infiltration, and bolstering the performance of other green infrastructure technologies. However, many of these interactions are inadequately understood, particularly at spatial and temporal scales relevant to stormwater management. As such, the reliable use of trees for stormwater control depends on improved understanding of how and to what extent trees interact with stormwater, and the context-specific consideration of optimal arboricultural practices and institutional frameworks to maximize the stormwater benefits trees can provide.

ENVIRONMENTAL REVIEWS AND CASE STUDIES: Building Green Infrastructure via Citizen Participation: A Six-Year Study in the Shepherd Creek (Ohio)

Green infrastructure at the parcel scale provides critical ecosystem goods and services when these services (such as flood mitigation) must be provided locally. Here we report on an approach that encourages suburban landowners to mitigate impervious surfaces on their properties through a voluntary auction mechanism. We used an economic incentive to place rain gardens and rain barrels onto parcels in a 1.8-km2 watershed near Cincinnati, Ohio. A comprehensive hydrologic, water-quality, and ecological monitoring campaign documented environmental conditions before and after treatment. In 2007 and 2008, we engaged private landowners through a reverse auction to encourage placement of one rain garden and up to four rain barrels on their property. The program led to the installation of 83 rain gardens and 176 rain barrels onto more than 20% of the properties, and preliminary analyses indicate that the overall discharge regime was altered by the treatments. The length of the study (six years) may have precluded observation of treatment effects on water quality and aquatic biological communities, as we would expect these conditions to respond more slowly to management changes. These distributed storm-water installations contributed to ecosystem services such as flood protection, water supply, and water infiltration; provided benefits to the local residents; and reduced the need for larger, expensive, centralized retrofits (such as deep tunnel storage).

Adaptive governance to promote ecosystem services in urban green spaces

Managing urban green space as part of an ongoing social-ecological transformation poses novel governance issues, particularly in post-industrial settings. Urban green spaces operate as small-scale nodes in larger networks of ecological reserves that provide and maintain key ecosystem services such as pollination, water retention and infiltration, and sustainable food production. In an urban mosaic, a myriad of social and ecological components factor into aggregating and managing land to maintain or increase the flow of ecosystem services associated with green spaces. Vacant lots (a form of urban green space) are being repurposed for multiple functions, such as habitat for biodiversity, including arthropods that provide pollination services to other green areas; to capture urban runoff that eases the burden on ageing wastewater systems and other civic infrastructure; and to reduce urban heat island effects. Because of the uncertainty and complexities of managing for ecosystem services in urban settings, we advocate for a governance approach that is adaptive and iterative in nature—adaptive governance—to address the ever changing social order underlying post-industrial cities and offer the rise of land banks as an example of governance innovation.

Development of a multidisciplinary approach to assess regional sustainability

There are a number of established, scientifically supported metrics of sustainability. Many of the metrics are data-intensive and require extensive effort to collect data and compute the metrics. Moreover, individual metrics do not capture all aspects of a system that are relevant to sustainability. A pilot project was initiated to create an approach to measure, monitor, and maintain prosperity and environmental quality of a regional system. The goal was to produce a straightforward, inexpensive methodology that is simple to use and interpret. This requires historical data be readily accessible, metrics must be applicable to the relevant scale, and results must meet the needs of decision-makers. Because sustainability is a multidimensional concept, the research group consisted of a multidisciplinary team that identified the major components of an environmental system. We selected metrics to capture the multidimensionality of sustainability in environmental systems and included: (1) emergy to capture the quality-normalized flow of energy through the system; (2) ecological footprint to capture the impact of humans on the system; (3) green net regional product to estimate human prosperity and well being within the system; and (4) Fisher information to capture the dynamic order of the system. We were able to compute metrics for a test geographic region using existing datasets. Preliminary analysis indicates that each metric reveals a somewhat different trend. These preliminary findings support the idea that characterization of sustainability requires a multidisciplinary approach and demonstrate the need to measure multiple aspects of an environmental system.

Introduction to the special collection of papers on the San Luis Basin Sustainability Metrics Project: A methodology for evaluating regional sustainability

This paper introduces a collection of four articles describing the San Luis Basin Sustainability Metrics Project. The Project developed a methodology for evaluating regional sustainability. This introduction provides the necessary background information for the project, description of the region, overview of the methods, and summary of the results. Although there are a multitude of scientifically based sustainability metrics, many are data intensive, difficult to calculate, and fail to capture all aspects of a system. We wanted to see if we could develop an approach that decision-makers could use to understand if their system was moving toward or away from sustainability. The goal was to produce a scientifically defensible, but straightforward and inexpensive methodology to measure and monitor environmental quality within a regional system. We initiated an interdisciplinary pilot project in the San Luis Basin, south-central Colorado, to test the methodology. The objectives were: 1) determine the applicability of using existing datasets to estimate metrics of sustainability at a regional scale; 2) calculate metrics through time from 1980 to 2005; and 3) compare and contrast the results to determine if the system was moving toward or away from sustainability. The sustainability metrics, chosen to represent major components of the system, were: 1) Ecological Footprint to capture the impact and human burden on the system; 2) Green Net Regional Product to represent economic welfare; 3) Emergy to capture the quality-normalized flow of energy through the system; and 4) Fisher information to capture the overall dynamic order and to look for possible regime changes. The methodology, data, and results of each metric are presented in the remaining four papers of the special collection. Based on the results of each metric and our criteria for understanding the sustainability trends, we find that the San Luis Basin is moving away from sustainability. Although we understand there are strengths and limitations of the methodology, we argue that each metric identifies changes to major components of the system.

Biological invasions, ecological resilience and adaptive governance

In a world of increasing interconnections in global trade as well as rapid change in climate and land cover, the accelerating introduction and spread of invasive species is a critical concern due to associated negative social and ecological impacts, both real and perceived. Much of the societal response to invasive species to date has been associated with negative economic consequences of invasions. This response has shaped a war-like approach to addressing invasions, one with an agenda of eradications and intense ecological restoration efforts towards prior or more desirable ecological regimes. This trajectory often ignores the concept of ecological resilience and associated approaches of resilience-based governance. We argue that the relationship between ecological resilience and invasive species has been understudied to the detriment of attempts to govern invasions, and that most management actions fail, primarily because they do not incorporate adaptive, learning-based approaches. Invasive species can decrease resilience by reducing the biodiversity that underpins ecological functions and processes, making ecosystems more prone to regime shifts. However, invasions do not always result in a shift to an alternative regime; invasions can also increase resilience by introducing novelty, replacing lost ecological functions or adding redundancy that strengthens already existing structures and processes in an ecosystem. This paper examines the potential impacts of species invasions on the resilience of ecosystems and suggests that resilience-based approaches can inform policy by linking the governance of biological invasions to the negotiation of tradeoffs between ecosystem services.

Using Self-Organizing Maps to Explore Patterns in Species Richness and Protection

The combination of species distributions with abiotic and landscape variables using Geographic Information Systems can prioritize areas for biodiversity protection by identifying areas of high richness, although the number of variables and complexity of the relationships between them can prove difficult for traditional statistical methods. The use of these methods, which commonly assume linearity and low correlation between independent variables, can obscure even strong relationships and patterns. Self-Organizing Maps (SOM) is a heuristic statistical tool based on machine learning methods that can be used to explore patterns in large, complex datasets for linear and nonlinear patterns. Here we use SOM to visualize broad patterns in species richness by taxonomic group (birds, mammals, reptiles, and amphibians) and 78 habitat, landscape and environmental variables using data from the Gap analysis project for West Virginia, USA. Soil and habitat variables demonstrated clear relationships with species richness; areas with high species richness occurred in areas with high soil richness. Landscape metrics were less important, although habitat diversity and evenness indices were positively related to species richness in some taxonomic groups. Current coverage of protected areas (e.g., National Forests and state parks) appeared to be insufficient to cover most of the areas of high species richness, especially for reptiles; many of the polygons with the highest richness were not covered by these areas. The identification of polygons with high richness and low protection can be used to focus conservation efforts in those areas.

Influence of catchment land cover on stoichiometry and stable isotope compositions of basal resources and macroinvertebrate consumers in headwater streams

Anthropogenic land use affects aquatic landscapes. For example, landscape-level conversion to urban or agricultural land can heavily influence nutrient cycles in headwater streams via increased nutrient loading and altered hydrologic patterns. Recent studies in headwater streams have found that the stoichiometry and stable isotope compositions of basal resources and consumers can vary as a result of landscape-level change. To this end, we examined the stoichiometry and stable isotope compositions (δ13C and δ15N) of headwater stream flora and fauna in 16 streams located within forested, agricultural, urban, and mixed (urban, forested, and agricultural) catchments. Our results suggest basal resource stoichiometry varied across streams, with leaf litter being the most variable basal resource. Macroinvertebrate consumers maintained stoichiometric homeostasis across stream groups, but consumer stoichiometry differed across families. Values of δ13C did not vary across stream groups for basal resources; however, consumer δ13C did. Although δ15N did not differ among basal resources across stream groups, macroinvertebrate consumer δ15N differed because of the interaction between stream group and family. Our results show catchment land cover did not predictably alter the stoichiometry or stable isotope compositions of basal resources or consumers in headwater streams. The quality of basal resources in headwater streams could differ across catchments with varying land cover, but it is evident that differences in stoichiometry of basal resources did not lead to differences in stoichiometry of consumers in our study. Given the variability of stable isotope compositions, additional effort should be made to improve our understanding of the landscape factors that might influence isotopic data.