Diversity: The key to resilience in forest ecosystems

Canada’s forests are home to about 140 native tree species across the country, as well as a great variety of plants, insects, fungi, birds, mosses, lichens, and more. Of the 426 bird species that breed in Canada, about one-third depend on forests to survive. Forest characteristics such as age, composition and structure influence what species are able to thrive in Canada’s forests, and these forest characteristics are primarily driven by forest disturbances. Disturbances can be of natural origin, such as forest fires ignited by lightning, ice storms, and native insect outbreaks and diseases (e.g., wood decay). They can also be human-induced, such as forest logging, land-use change and invasive pest outbreaks.

Biodiversity and resilient forests

Forest resilience to disturbances is closely related to biodiversity and its preservation. Generally, a forest with greater genetic, species, and habitat diversity is more resilient than one with less diversity. High genetic diversity within managed and unmanaged forests allows species to gradually adapt to changing environmental conditions, including climatic changes and outbreaks of forest insect pests and pathogens. For example, on the whole, Canada’s boreal forests have relatively low tree species diversity, yet these species are highly adaptable because of their genetic diversity and large population size.

Species diversity increases forest resilience through the presence of species with special characteristics, called functional traits (characteristics that allow the organisms to survive and reproduce), which can help them return after a disturbance has occurred. A forest having all of its parts – including a range of habitats and young and old stands – can host more species, among which some will be able to re-establish after a disturbance, thanks to their special functional traits.

Assessing biodiversity to better protect it

Quantifying forest biodiversity is of paramount importance to understand the impacts of disturbances on forest ecosystems over time. However, given the high number of species and the vastness of the territory, assessing forest biodiversity can be challenging. Despite this challenge, there are still many ways to assess biodiversity, such as focusing on targeted species groups (e.g., species at risk), specialized species that need particular habitat conditions to survive and sensitive species that are known to respond negatively to disturbances or using forest habitat conditions as an indicator of species diversity. We need to assess biodiversity in managed forests to monitor the efficiency of our management strategies to maintain suitable habitat conditions for the targeted species. It is also important to monitor changes in biodiversity over time in unmanaged forests to be aware of the arrival of new species in Canada and of species that could decline because of human activities (e.g., pollution and habitat loss).

There are several ongoing projects that are working to improve our understanding of biodiversity in Canada’s forests. Academic and government scientists are consistently collecting new forest biodiversity data and documenting the use of the forest environment as habitat. For example, the Boreal Avian Modelling Project (BAM) collects and collates avian (bird) data from across Canada and uses these data to create habitat maps that predict how the abundance of birds will change in response to habitat loss and changes in habitat connectivity and fragmentation, among other changes. The growth of Citizen Science initiatives for collecting data, such as eBird, the Breeding Bird Survey, and the Breeding Bird Atlas, provides opportunity for knowledgeable Canadians to contribute to scientific projects like BAM.

Partnerships between Indigenous monitoring programs, such as the Boreal Sentinel Project, and western scientific researchers are also growing more common and leading to a whole new perspective on forest biodiversity through “two-eyed seeing.” The Boreal Sentinel Project is a partnership between Canadian Forest Service researchers at the Atlantic Forestry Centre, Miawpukek First Nation of Newfoundland and Labrador, and Parks Canada that aims to develop an early warning system for biodiversity loss using inventories of species in the field, an automated monitoring system with digital cameras, participatory science, and Indigenous science and knowledge. So far, the Forest Guardians of the Miawpukek Nation have taken an inventory of lichens in Gros Morne National Park and discovered several new species of lichens previously unknown to exist in this national park. A new phase of the project is expanding the area of interest to include Terra Nova National Park, an ecosystem corridor between the park and a new Forest Management Area managed by Miawpukek First Nation, and the Miawpukek First Nation’s reserve.

Maintaining biodiversity and resilience in Canada’s managed forests

The best available scientific research and information are used to plan and implement sustainable forest management practices in Canada. The Montréal Process set out indicators for measuring sustainability of forest management practices. Criterion 1 of the Montréal Process is to conserve biological diversity. To meet this criterion, sustainable forest management must consider forest diversity at the genetic, species, and landscape scales. Numerous laws and regulations across Canada also require forest managers to conserve biodiversity, including species at risk.

The best-known strategy for managing and conserving biodiversity is to ensure that a range of forest ages, composition, and structure are spatially connected across landscapes. In addition to preserving critical habitat for species at risk, forest managers can maintain forest ecosystem resilience by using management practices inspired by natural disturbances such as fires and insect outbreaks. Initiatives such as the Ecosystem Management Emulating Natural Disturbance (EMEND) Project inform such management practices by testing the effects of residual forest structure on forest biodiversity, such as leaving live single trees and large patches of uncut forests within harvested areas.

Climate change: A game changer for the resiliency of Canada’s forests

Canadian forests are well adapted to natural disturbances, but climate change is changing the frequency, severity and size of disturbances and facilitating the movement of forest pests. The increase in disturbances may transform forest composition. For example, the anticipated increase in fire frequency and severity may benefit some species that could take advantage of the new conditions (e.g., pines, white birch and red oaks), while other species could decline (e.g., sugar maple, American beech, and eastern hemlock). The rate of climate change in Canada also means that some tree species will not migrate quickly enough to maintain viable populations.

The speed and scale of climate change can make Canada’s forests vulnerable

Climate-smart forestry for resilient future forests

Climate change is challenging the resiliency of Canada’s forests, but research and innovation are leading to solutions. Advances in ecological modelling have provided greater insight in how species diversity and forest ecosystems may respond to a changing climate. For example, modellers are now able to utilize biodiversity data, such as those collected through BAM, citizen science, and Indigenous monitoring programs, with climate models to forecast how bird diversity will respond to climate-induced changes to forest habitats. Additionally, climate and habitat modelling can provide insight into areas that may change less over time (e.g., climate refugia), indicating priority areas for biodiversity conservation.

Genomics is also proving to be a powerful tool to understand the genetic and functional trait diversity of our forests and leading to innovative approaches to selecting seed sources for regenerating forests better suited to future climate conditions. For example, the recent FastPheno initiative aims to accurately assess the response of trees to environmental variations in near real-time through the use of next-generation drones at operational scale and will provide unprecedented capabilities for quantifying the adaptive characteristics of tree species. Also, the Traits of Plants in Canada (TOPIC) network is a group of university and government researchers studying the functional traits of plants and trees to develop a better understanding of species vulnerability and adaptability to climate change. By sharing information, these projects help answer important ecological questions and support policy decisions for enhancing the resilience of forests.

Finally, new experimental approaches to adaptive silviculture (the harvesting and regeneration of forests) are being tested through different projects. For example, Silva21 is a national research program aiming to provide data, tools and practical solutions to improve the resilience of our forests. The Canadian Forest Service’s Petawawa Research Station also hosts Canada’s first Adaptive Silviculture to Climate Change trial.