Michael Brereton NRS 534 Final White Paper

Roadside

There are very few species in the recent history of our planet Earth that have made such a lasting impact on the surface of the world as us. Human activity has left the landscape of our planet forever changed as we continue to expand our territory to fit our exponentially growing population. One of the signs of a rapidly growing civilization is the . Whether paved or dirt, are used by humans to transport ourselves great distances at the cost of our natural surroundings. Roads are a major driver of , a term used in ecology to describe the fracturing or dividing of a natural landscape type by an impassible barrier. The creation of roads clears large areas of land and reduces forest cover, furthering an ever-growing loss of habitat for arboreal species to human growth. The constant mowing of roadsides allow invasive exotic species to colonize. Roads can reduce the range for foraging and hunting , and those who dare to cross risk death by . Roads can also change the physical aspect of an environment, causing greater risk to and flooding. In order to continue living in harmony with the flora and fauna of our natural surroundings, we must employ new ideas and technologies to our roads. The study of road ecology will provide the answers we need to have safer roads for both ourselves and our natural world. Road ecology sits at the crossroads between many different scientific fields, including invasion ecology, , stream ecology, soil science, and many more. But just what is “road ecology”. One of the first, if not the first, mention of this term can be found in a paper by Richard Forman and Lauren Alexander in 1998 called “Roads and their Major Ecological Effects”. While the paper does not give a clear definition for the term, the concept is introduced as the study of the effects of roads and their surrounding areas on ecosystems. A key contribution of this paper is its discussion of the “road-effect zone”. This illustration is the result of Forman and Alexander’s accumulated research into the effects of roads on various features of the . According to them, actions such as salting or paving roads can to aquatic leaching within 50 meters of the road, sediment pollution and invasion of cleared areas by exotic plant species can have an impact around 1 kilometer from the road. Many impacts of roads are discussed in this paper, including invasive species, hydrology, sediment leaching, and drastic habitat change. One of the major problems of roads that are discussed in the literature I have found is the creation of edge or barrier effects. Many plants and animals depend on large areas to reproduce, forage, and hunt. For example, a study done on small mammals in the Czech Republic showed that roads negatively impact on two vole and one mouse species. These rodents were inhibited by the roads and could not pass safely, significantly reducing their range and ability to forage. However, the ability of these small mammals to cross was found to be directly related to the width of the road,

Michael Brereton NRS 534 Final White Paper as animals were more likely to make it across thin roads (Rico et al, 2007). Eastern hognose snakes (Heterodon platirhinos) have also been observed to change their movement behavior based on roads, only crossing roads with no pavement (Blouin- Demers and Robston, 2013). The barrier effect can even lead to severe population-wide effects on a species. Genetic diversity can be significantly reduce if a population becomes isolated due to barriers. A 2003 study of shows that major road construction can lead to loss of genetic variability and gene flow in Swiss ground beetles (Keller and Largiader, 2003). This can have disastrous consequences on species that already have shrinking numbers or low reproductive numbers. As said by Shaffer and Samson (1985), “Fragmentation may be more critical than area as a determinant of probabilities”, when considering species with low reproduction. Areas affected by fire and drought are more likely to suffer loss of species due to the fragmentation as resources become quite thin for animals surrounded by impassable roads (Andrews, 1990). While roads themselves produce unsafe barriers to animals populations, vegetation can also be affected. The effects of roadways on nested land cover types in the northern Great Lakes have been quantified and discussed in a paper by Saunders et al (2002). In this paper, the effects of roads on eight major land cover types are analyzed and presented. The edge effect provided by the roads creates patches of forest on the Wisconsin landscape, and these units are distinguishable via satellite.The patch type, density, and abundance were all affected, with patch size decreased and patch abundance increasing. This change in forest connectivity is shocking, and it is noteworthy that of the 78,752 km2 analyzed in the study, only 205 km2 were found to be original undisturbed land. In addition to fracturing forest land cover, road edges have introduced changes that affect natural selection of plants. The appearance of mowed or cleared roadsides has created a disadvantage for many native plant species who are not very tolerant of frequent disturbance. A study done in southern Utah confirmed that large paved roads create significant edge effects up to 200m from the road and reduce both the abundance and diversity of native plants (Belnap and Gelbard, 2003. The same study noted that the richness of exotic species was 50% greater in paved roads compared to smaller four-wheel-drive tracks, further cementing the idea that paved road create more disturbance. Despite the threat of exotic species, some native plants can reap benefits from edge effects. One study in England showed that healthland plants, specifically heath and grasses, actually increased their growth in response to being in close proximity to the road (Angold, 1997). This study also suggests that the size of the road and frequency of traffic may directly increase to the amount of disturbance taking place. Eutrophication from the road is identified as a source of increased growth, as nitrogen from the exhaust provides nutrition for certain heather and grass species (Angold, 1997).

Michael Brereton NRS 534 Final White Paper

This type of chemical disturbance reminds us that not only do roads disturb the ecological structures along their edges, but the physical and chemical components of these environments. Roads can also greatly affect the hydrology and geomorphology of an area. Paved roads create layers, which have been observed to significantly alter the flow of water within an environment. Impervious surface creates a shift in the flow of water from subsurface flow to almost exclusively surface runoff (Shuster et al, 2005). This causes redistribution of water resources at a level much more related to the slope of an area, as rainwater flows downhill along the surface of the road without permeation. This surface effect also means that flooding can result from smaller precipitation events than in environments with less impervious surface (Shuster et al, 2005). The altered balance between peak flood levels in response to roads is also confirmed by Jones et al (2000). Jones et al (2000) reviews the effects of roads on hydrology and geomorphology in roadside streams. The paper concludes that roads can serve as both the source and sink for flood debris depending on their location and can increase both the magnitude and frequency of debris flows from (Jones et al, 2000). An increase in severe flooding can change the disturbance level in an environment and hinder the growth and recovery of riparian zones and stream ecosystems (Jones et al, 2000). The redistribution of water flow and increase in flood intensity shows the powerful effect of roads on both the biological and physical aspects. With the threat of road-related environmental disturbance looming, what can the scientific world do? How are we to protect our precious ecosystems from barrier effects and fragmentation-caused extinction. One major breakthrough in road ecology is the concept of the wildlife corridor. These natural throughways provide wildlife the opportunity to cross high traffic roads without the danger of being struck by a vehicle. The danger of vehicular death on animals is summarized by both Forman and Alexander (1998) and Andrews (1990), as well as Rico et al (2007) in relation to small European mammals. However, the location and design of these corridors can greatly affect their success. In a 1993 study, the effects of road corridor design on Australian marsupial species are discussed. The amount of vegetation within the corridors affected the populations of these marsupials, as these species are herbivorous (Lindenmayer and Nix, 1993). The connectivity between the corridors along the road also played a major part in species survival, as well as the location of the corridors in relation to slope. For each wildlife corridor, the foraging and movement patterns of the species being conserved must be considered (Lindenmayer and Nix, 1993). The conclusion of this paper and many other studies on Australian mammals and roadsides were used to produce the blueprint for an Australian wildlife underpass project called East Evelyn Underpass Project (Goosem et al, 2001). This project helped created four large underpasses on East Evelyn Road in Queensland, Australia. These underpasses, while providing safe passage across a major road, also consider the foraging and movement

Michael Brereton NRS 534 Final White Paper

patterns of local species, such as goannas, cassowaries, and tree kangaroos (Goosem et al, 2001). In a follow-up report in 2003, Miriam Goosem confirmed that the underpasses were successful in reducing the animal mortality count along Evelyn Road (Goosem, 2003). The field of road ecology is ever-growing, and the growing support and research into wildlife corridors may help relieve the fragmentation that roads create. Road ecology is a strange combination of many different aspects of ecology coming together to try and understand a large-scale, man-made, structural change. It is incredible that such a seemingly simple structure like a road could have so many effects on our natural world. Ecology, , hydrology, botany, invasion science, and even engineering have been instrumental in the quest of understanding the environmental impacts of roads. Despite the innovations made in reducing the effect of roadside disturbance, much more in depth studies must continue to be produced. Wildlife corridors are effective at saving animals from fatal , but much more effort must be focused on roadside clearing disturbances and the edge effect. Only then will our impact on ecosystems be moderated and the biodiversity of our forest, grasslands, and be safe.

Annotated Bibliography

Andrews, Annabelle. "Fragmentation of Habitat by Roads and Utility Corridors: A Review." Australian Zoologist 26.3-4 (1990): 130-41.

This old, but comprehensive paper reviews the various effects of roads and other clearing on the fragmentation of habitat and wildlife. The review addresses many effects of clearings, including the loss of habitat, creation of edges, increased mortality of wildlife along roadsides, and even discusses hydrological changes in response to clearings. The introduction of wildlife barrier is a discussed in detail, and the idea that roads produce more of a threat to species with limited range and reproductive ability is also introduced. Ecological disturbances is not only described from a fragmentation perspective, as indirect causes for wildlife habit change such as and light disturbance are considered. The introduction of invasive species via roadside mowing is discussed, followed by a discussion of how improved human access to via roads can lead to loss in biodiversity. Overall, this paper gives a very balanced and all- encompassing review of roads and habitat fragmentation.

Angold, P. G. "The Impact of a Road Upon Adjacent Heathland Vegetation: Effects on Plant Species Composition." The Journal of Applied Ecology 34.2 (1997): 409.

A very interesting paper detailing the effects of road edge proximity on grassland plants in the English countryside. It is very interesting to note that while this paper concludes that there are negative effects caused by road on plant species, specifically lichens, there can also be

Michael Brereton NRS 534 Final White Paper positive effects resulting from roads. The added nitrogen from vehicle exhaust is shown to increase the abundance and growth of vascular plants along roadside edges. It is also shown that the increased growth of grasses may have resulted from a shift in competitive edge for these species, as these grasses could now grow faster and already posses a tolerance to physical disturbance. The paper also discusses the proximity of the edge effect, concluding that areas within a 200m of road (depending on traffic) could see effects related to the influx of nutrients. Recommendations are given to limit the amount of chemical exhaust disturbance from “environmentally sensitive” areas.

Forman, Richard T. T., and Lauren E. Alexander. "Roads And Their Major Ecological Effects." Annual Review of Ecology and Systematics 29.1 (1998): 207-31.

Often cited as the landmark paper of roadside ecology of the late 1990’s, this paper by Richard Forman and Lauren Alexander introduced the modern ideas of roadside ecology. Similar to the aforementioned Annabelle Andrews paper, this paper is a review of the research regarding the various effects of roads on ecosystems. One major breakthrough of this paper is the establishment of the ideas that roadkill, while fatal, does not have as much of an effect on wildlife as the edge effect provided by roads, which at the time was not extensively studied. The paper introduces the idea that certain populations can be isolated as a result of habitat fragmentation due to roads, reducing genetic diversity in metapopulations. The paper also discussed the effect of roads on chemical runoff and patch dynamics on forested ecosystems. The paper concludes that roadside ecology is a field that must be studied further and has a lasting impact on the ecology of surrounding ecosystems.

Gelbard, Jonathan L., and Jayne Belnap. "Roads as Conduits for Exotic Plant Invasions in a Semiarid Landscape." Conservation Biology 17.2 (2003): 420-32

The contributions of roads to exotic plant invasion in southern Utah are studied and discussed in this paper. Disturbance is a framework topic in the field of landscape ecology. Disturbance and invasion often go hand and hand, as shown in the results of this study of roadside desert vegetation. The constant disturbance from the roads in Utah are discussed, including mowing of roadside areas, herbicide treatment, wind and chemical disturbance of seedling plants, and addition of roadfill. One interesting developement of this study is the importance of the type of road on vegetation communities. In areas that had much more traffic and pavement, the presence of the invasive grass Bromus tectorum was three times as common (27%) than in areas with simple dirt roads (9%). Alternative tactics for clearing roadsides are also discussed in this paper, including more accurate herbicide treatments and reduced mowing in areas with rare species.

Goosem, Miriam, Yoshimi Izumi, and Stephen Turton. "Efforts to restore habitat connectivity for an upland tropical rainforest fauna: A trial of underpasses below roads." Ecological Management and Restoration 2.3 (2001): 196-202.

Michael Brereton NRS 534 Final White Paper

This paper introduces a proposed wildlife corridor project for East Evelyn Road, a major road in Queensland, Australia. In this proposal, the effects of various other corridor projects are summarized, as well as the process of creating a wildlife corridor. The paper discussed how wildlife corridors must not only serve as passageways, but they must themselves be welcoming environments providing food and shelter to the native wildlife. Planting of trees and introduction of permeable surfaces to prevent disturbance to hydrological regimes is discussed. The paper also highlights the importance of constant vigilance and the need for an established evaluation protocol for wildlife underpasses. The results of the underpass project are discussed in a follow- up report.

http://search.informit.com.au/documentSummary;dn=685627052621737;res=IELENG

Jones, Julia A., Frederick J. Swanson, Beverley C. Wemple, and Kai U. Snyder. "Effects of Roads on Hydrology, Geomorphology, and Disturbance Patches in Stream Networks." Conservation Biology 14.1 (2000): 76-85. Web.

This paper focuses on both the physical effects and ecological effects that roads produce in relation to hydrology and flood disturbance. The paper discusses how changes in water flow affect the movement of water in stream ecosystems. The disturbance of flood regimes is reviewed and linked to the ecological resilience of riparian areas. The effects of changes in hydrology on patch dynamics is also discussed, as model for stream layout and slope changes based on water flow are linked to fragmentation. This paper introduces models for detecting the magnitude of changes resulting from altered debris flow and flood regime on land stratification. A model for stream designation based on location on downslope areas and midslope areas in relation to road proximity is also introduced.

Keller, I., and C. R. Largiader. "Recent habitat fragmentation caused by major roads to reduction of gene flow and loss of genetic variability in ground beetles." Proceedings of the Royal Society B: Biological Sciences 270.1513 (2003): 417-23

Unlike many of the papers presented in this review, this paper looks at the effects of roads on a microscopic scale as opposed to a larger landscape scale. The genetic variation of Carabus violaceus, a ground beetle native to the forests of Switzerland. The study focuses on beetle populations found within certain ecosystems that have roads within a given distance of each other. These fragmented areas are chosen in relation to both the density of road cover in the area and the types of roads present. FSTATs are used to calculate the genetic differentiation between eight groups found in areas with differing road densities and types. A Mantel statistic test was then used to find the relationship between road density according to satellite data on road coverage and the genetic diversity (allelic richness) of the beetle populations in the test sites. The study found that large roads may be absolute barriers to gene flow across beetle metapopulations. Also, the smallest forested fragment produced the lowest amount of genetic diversity, furthering the support of this idea.

Michael Brereton NRS 534 Final White Paper

Lindenmayer, David B., and Henry A. Nix. "Ecological Principles for the Design of Wildlife Corridors." Conservation Biology 7.3 (1993): 627-31.

Differing designs for wildlife corridors are reviewed in this 1993 paper. It is intriguing to see the earlier stages of developing models to reduce the risk of animal road fatalities in the early 90’s. Several papers that were talked about in this paper were cited in other papers in this white paper, including the Forman and Alexander review from 1998. Wildlife metrics such as diet, range, body weight and size, and amount of corridors allocated for each conserved species are analyzed as factors in determining corridor success. It is fascinating to see how early ideas of corridor creation stemmed from this paper, as ideas such as landscape connectivity in context with food web relationships are discussed. This paper also brings forward the idea that corridors can be environments within themselves, not just gateways between two areas. If the connectivity between two areas is constructed in a way that reduces the disturbance of roads, it is unlikely that they will serve their purpose.

Shuster, W. D., J. Bonta, H. Thurston, E. Warnemuende, and D. R. Smith. "Impacts of impervious surface on watershed hydrology: A review." Urban Water Journal 2.4 (2005): 263-75

This paper does not dwell on the ecological aspects of roadside areas, but rather explores the physical effects of urban growth on water flow within environments. The main focus of this review is how the increase in impervious surface due to the of the last century has adversely affected water flow and flooding in developed areas. Within these areas, the onset of severe flooding is more rapid in relation to the timing of precipitation than those with less impervious surface. It also takes less overall precipitation to flood an area with impervious surface. The changes in hydrology can cause disconnections between ecosystems by stopping the flow of water downhill within the soil, preventing water-soluble nutrients from entering certain areas. These changes to hydrology can adversely affect ecology, as the increased speed and frequency of floods create both physical disturbance and chemical disturbance in the form of nutrient leaching and eutrophication.

Robson, Laura E., and Gabriel Blouin-Demers. "Eastern Hognose Snakes (Heterodon platirhinos) Avoid Crossing Paved Roads, but Not Unpaved Roads." Copeia 2013.3 (2013): 507-11.

This is probably the most behavior-related paper I have presented in my final. This study looks at the differences in road crossing of eastern hognose snakes (Heterodon platirhinos) in relation to the natural surface cover of roads. Supporting the earlier assertions of other papers (including several cited in this white paper), it was found that hognose snakes are not only cross unpaved roads more than paved ones, but are completely unhampered in doing so. This suggests that ground animals may not be as adversely by the road clearings themselves, but the physical makeup of the road itself.

Michael Brereton NRS 534 Final White Paper

Saunders, Sari C., Mo R. Mislivets, Jiquan Chen, and David T. Cleland. "Effects of roads on landscape structure within nested ecological units of the Northern Great Lakes Region, USA." Biological Conservation 103.2 (2002): 209-25.

The effect of roads on larger landscape units are reviewed in this paper. Eight distinct ecological units in the Wisconsin forest system are used to analyze the effect of road density on landscape fragmentation. A term that is introduced in this paper is DEI (depth of edge influence), meaning the average depth of the effects of ecological barriers provided by roads. It was found that 5-60% of the forest units were affected by the presence of roads, depending on the DEI. The use of biodiversity statistics in this paper (FRAGSTATS), as well as land cover data and road cover data (TIGER) really sets this paper apart from others as a quantitative study of fragmentation effects in forest ecosystems.