L-ACER
Lichens, Acidification, and Cut Edge Response
Research overview
The cool, humid forested wetlands of Nova Scotia are home to a diverse and unique community of lichens, including several rare and sensitive species. Unfortunately, habitat loss and degradation have impacted these communities, and the populations of some sensitives species are declining within the province. The overarching goal of our project is to understand how forest clearcutting, habitat acidification and slug herbivory affect at-risk lichen communities in the forested wetlands of Nova Scotia, Canada.
Our main focus is how edge influence, caused by forest cutting, influence lichens in adjacent, uncut areas. Edge influence refers to a phenomenon where environmental and biological conditions at a forest edge extend into the interior forested area, thus influencing the communities there. Effects can be changes in temperature, light, wind, humidity, nutrient cycling, and even species interactions. As certain lichens are quite sensitive, even seemingly small changes in their environment may have big impacts on their communities. Our second focus is how acidification of substrates, via pollution and acid precipitation, affects lichen communities. Pollution is often thought to play a role in the decline of sensitive lichen communities, yet to date there are no long-term studies on the impact of acidification on lichens in Nova Scotia. In the past, we have also focused on the impact of grazing by non-native slugs on these communities, which we expect might be greater at clearcut edges.
Our research will help land managers better understand the impact of cutting on sensitive lichen communities and enact policies for conservation. Our study will also help determine whether acidification is responsible for declines in lichen communities and whether remediation treatments can help improve diversity at impoverished sites. Our research on non-native slugs has already contributed to a better understanding of the impact they have on these communities.
Port Hawksbury Paper and Mitacs are our partners for this project.
Our main focus is how edge influence, caused by forest cutting, influence lichens in adjacent, uncut areas. Edge influence refers to a phenomenon where environmental and biological conditions at a forest edge extend into the interior forested area, thus influencing the communities there. Effects can be changes in temperature, light, wind, humidity, nutrient cycling, and even species interactions. As certain lichens are quite sensitive, even seemingly small changes in their environment may have big impacts on their communities. Our second focus is how acidification of substrates, via pollution and acid precipitation, affects lichen communities. Pollution is often thought to play a role in the decline of sensitive lichen communities, yet to date there are no long-term studies on the impact of acidification on lichens in Nova Scotia. In the past, we have also focused on the impact of grazing by non-native slugs on these communities, which we expect might be greater at clearcut edges.
Our research will help land managers better understand the impact of cutting on sensitive lichen communities and enact policies for conservation. Our study will also help determine whether acidification is responsible for declines in lichen communities and whether remediation treatments can help improve diversity at impoverished sites. Our research on non-native slugs has already contributed to a better understanding of the impact they have on these communities.
Port Hawksbury Paper and Mitacs are our partners for this project.
What are forest edges and why do we study them？
Whether natural or human-caused, forest edges are integral components of the landscape. A forest edge is the interface between two ecosystems, typically a forested and non forested areas but can also be the transition between an upland forest and a forested wetland.
As our landscape becomes more fragmented, forest edges play a larger role in shaping our ecosystem. It is important to understanding the extent to which conditions at the edge influence the interior forest. These effects may have substantial effects on biodiversity, in particular for sensitive species that are reliant on interior and undisturbed forests.
As our landscape becomes more fragmented, forest edges play a larger role in shaping our ecosystem. It is important to understanding the extent to which conditions at the edge influence the interior forest. These effects may have substantial effects on biodiversity, in particular for sensitive species that are reliant on interior and undisturbed forests.
Forested wetlands in Nova Scotia
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Nova Scotia is known for it's lighthouses and beaches, but unknown to many is that it is the wetlands harbour some of the province's greatest biodiversity.
Wetlands are places where water is at or near the surface for most or all of the year. Bogs, fens and swamps are all examples of wetlands. They are often interspersed within low-lying areas forests. Wetlands are important for the environment because they help clean the water, store the water, protect the land, and support many living things. Wetlands are also influenced by forest edges. Some of these edges are natural such as the transition into the drier, upland forest. Others, however, are bounded by human created edges, such as clearings and forest cuts. Conditions at the edge can influence wetlands further into the interior and affect species that live there. |
Sphagnum sp.
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Lichens of Nova Scotia's forested wetlands
Lichens are often times mistaken for plants. Like plants, lichens make their own food, and some have forms that strongly resemble leaves in shape and colour. However, a lichen is actually formed by an association between one or more fungi and a photosynthetic partner, either a green algae or a cyanobacteria. Together, they form a unique body, which can have different shapes and colours depending on the species involved. Lichens can be found on a variety of habitats and substrates. In forested wetlands, they are most commonly found on trees.
The lichen association is often though of as a relationship that benefits both the fungal part and it's photosynthetic partner. The photosymbiont (green algae or cyanobacteria) provide the fungus with food via photosynthesis, using sunlight and water to make their own food, just as plants do. In turn, the fungus provides the photosymbiont with a protective home.
Lichens that contain a cyanobacteria (called cyanolichens) are found in wetlands, mostly on red maple and yellow birch trees. Globally, these lichens are rare, but Nova Scotia's wetlands have a surprisingly high diversity of cyanolichens, including many rare and at-risk species. Cyanolichens are important in these ecosystems because they provide a home and forage for invertebrates and are also able to fix nitrogen- making it into a form that is useable for themselves and other plants and animals. Nitrogen is essential for all living organisms.
Cyanolichens tend to be more sensitive to environmental change than other lichens, and are often used as indicators of environmental quality and habitat continuity. Unfortunately, some populations of cyanolichens are declining in Nova Scotia, likely due to air pollution, forest cutting, climate change, invasive slugs, and habitat loss. Currently, we are investigating substrate acidification the secondary effects of forest cutting may be impacting cyanolichen communities in these wetlands. In the past, we studied the impacts of invasive slugs on these communities.
The lichen association is often though of as a relationship that benefits both the fungal part and it's photosynthetic partner. The photosymbiont (green algae or cyanobacteria) provide the fungus with food via photosynthesis, using sunlight and water to make their own food, just as plants do. In turn, the fungus provides the photosymbiont with a protective home.
Lichens that contain a cyanobacteria (called cyanolichens) are found in wetlands, mostly on red maple and yellow birch trees. Globally, these lichens are rare, but Nova Scotia's wetlands have a surprisingly high diversity of cyanolichens, including many rare and at-risk species. Cyanolichens are important in these ecosystems because they provide a home and forage for invertebrates and are also able to fix nitrogen- making it into a form that is useable for themselves and other plants and animals. Nitrogen is essential for all living organisms.
Cyanolichens tend to be more sensitive to environmental change than other lichens, and are often used as indicators of environmental quality and habitat continuity. Unfortunately, some populations of cyanolichens are declining in Nova Scotia, likely due to air pollution, forest cutting, climate change, invasive slugs, and habitat loss. Currently, we are investigating substrate acidification the secondary effects of forest cutting may be impacting cyanolichen communities in these wetlands. In the past, we studied the impacts of invasive slugs on these communities.
Non-native slugs |
Lichens in forested wetlands are affected by grazing by non-native slugs, such as Arion spp., which are becoming a concern for land managers in Nova Scotia, Canada. They appear to have a highly diverse diet and may pose a particular risk to native slug species and to rare or at-risk lichens. In Nova Scotia, non-native slugs are generally thought to increase grazing pressure on rare and at-risk lichens. We found that forested wetlands across Nova Scotia are dominated by non-native Arion species that benefit from road systems and non-forested habitats in the surrounding landscape.
