Adaptation of Forests to Climate Change: Is It Possible?
Urbión Model Forest in Castilla y León, Spain (Image Credit: Julia Ramsauer)
In a world in which it’s still tough to convince many people that climate change is a very real phenomena, figuring out ways to tackle climate change is an even more difficult problem to wrap our heads around. In general, there are two strategies we can use: (1) mitigation (reducing the accumulation of greenhouse gases in the atmosphere) and, (2) adaptation (reducing the vulnerability of societies and ecosystems facing the impacts of climate change).
In my last piece (linked here), I wrote about the effects of climate change on forests. But what about the reverse, and their potential to mitigate climate change? Forests are crucial for climate change mitigation – they literally suck carbon out of the atmosphere. At the same time, forest adaptation will be necessary to avoid degradation of forest ecosystems due to a changing climate: an extremely complex task.
Forest ecosystems are threatened by climate change due to changes in temperature and precipitation, and due to more frequent or more intense disturbances like fire, drought, or pests. Fortunately, humans have a long history of managing forests. Combining our historical knowledge with more recent scientific research and our projections of how the climate will change over the coming decades has produced a wealth of adaptation measure. Let’s dive into them.
What is Adaptation?
Before I elaborate further on adaptation measures, let’s define the concept itself in this context and what drives our decision-making. According to the IPCC, adaptation is “an adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities.” It’s similar to what we do daily – if a relative is coming to visit with their kids, you might put away any easily breakable objects to adapt your site to the ‘increase in extreme events’ that you’ve forecasted.
The first step to understanding what kind of adaptation adjustments might be necessary for a particular site, is to assess the vulnerability of that site to climate change. As you can see in the figure below, vulnerability is composed of two components: the potential impacts (exposure and sensitivity) on the forest, which increases its vulnerability, and the adaptive capacity of the forest, which can decrease its vulnerability. Species can adapt to climate change through phenotypic plasticity (commonly termed acclimatization – a process whereby plants grow in a manner more suitable to their surroundings), adaptive evolution, or migration to suitable sites. However, these are processes which are usually employed to allow plants to survive changes which take thousands or even millions of years. Many scientists are concerned that this is not sufficient to successfully withstand the unprecedented speed of climate change. This is where adaptation measures kick in.
Forest Adaptation Measures
We can separate adaptation measures into two broad categories. The first are measures that aim to buffer a system from perturbations by increasing its resistance and resilience to change. Resistance is the ability of a system to resist external disturbances, while resilience is the ability of a system to absorb disturbance and reorganize while changing to still retain essentially the same function, structure, identity, and feedbacks. Buffering measures are either designed to prevent disturbances (e.g. prescribed burning, invasive species management, or phytosanitary treatments to reduce pest outbreaks), or to actively manage the forest after a disturbance (e.g. favoring the establishment of adapted and acceptable species). Although such measures might seem favorable over actively changing the system, it is important to acknowledge that they might not be enough to keep up with the fast-changing environmental conditions and that they are quite expensive as intensive management is required. If a local species dies out due to increased temperatures, is it worth replanting it, knowing that the same thing will likely occur again?
The second type of measures aim to facilitate a shift or an evolution of the system towards a new state that suits the altered conditions. Such measures ease and manage natural adaptation processes. For instance, for forest plantations, management can be modified to adapt to climate change by adopting species and genotypes that are adapted to future climates, perhaps by being more drought tolerant. Another facilitating measure consists of conserving a large spectrum of forest types for their value and their possible higher resilience (e.g. biodiversity hotspots).
Applied Forest Adaptation Measures
So that’s the theory, now let’s look at the practice. Countless measures have been proposed and are already being applied to adapt forests to cope with the changes to come. Although the number of studies investigating forest adaptation to climate change has skyrocketed in the last couple of years, they are still mostly located in Europe and Northern America. Tropical forests and other specific site characteristics of forests in Africa, Asia, South America, and Australia have been neglected by researchers. Nevertheless, adaptation usually falls in one of the following categories:
- Sustain fundamental ecological functions like nutrient cycling in the soil or fire-adapted ecosystems
- Reduce the impact of biological stressors (e.g. pests or invasive species)
- Reduce the risk and long-term impacts of severe disturbances (e.g. fire)
- Maintain or create refugia
- Maintain and enhance species and structural diversity
- Increase ecosystem redundancy across the landscape
- Promote landscape connectivity by, for instance, maintaining and creating habitat corridors through reforestation or restoration.
- Maintain and enhance genetic diversity, for example by using seeds, germplasm, and other genetic material from across a greater geographic range.
- Facilitate community adjustments through species transitions (e.g. introduce species that are expected to be adapted to future conditions)
- Realign ecosystems after disturbance
When talking about climate change, a high level of uncertainty is always present. Thus, by adopting any of the above-mentioned strategies, even though we might successfully adapt a forest to the known challenges ahead, other challenges will likely arise along the way. Due to this, any adaptation strategy needs to follow a dynamic approach. You can set out a long-term plan, but you need to constantly monitor the plan along the way to make sure it’s still relevant. Any treatments and decisions need to be continually checked, along with research results, to modify management to suit changing objectives. Depending on the complexity of the forest system, uncertainty of the effect of adaptation measures varies. Selecting only a few of the above strategies might be relevant for systems with less complexity (e.g. large areas that might only house a few types of trees, like conifer forests) and exposed to clear trends in climate change. However, in most cases, a high degree of uncertainty mean managers will need to adapt many of these measures at the same time.
All Forests are Different, so Adaptation Should Be Too
Finally, let’s point out a few things to keep in mind that will likely benefit the adaptation process. Adaptations are very site-specific, so any policy developers need to be familiar with the site conditions and its history. Local forest managers or forest communities usually have profound knowledge about their forests, making them an important part of the decision making process. However, attention to local variation is typically seen as too difficult, too costly, or impractical. Institutional changes are needed to allow building adaptation at the local level, rather than trying to make broad-scale plans. Forests are very dynamic systems that provide economic, social, and ecological values. Thus, when forest adaptation strategies are decided on, all of these perspectives need to be taken into consideration. Decision-making on adaptation should be integrative by combining forests and society, inclusive across scales and sectors, and participatory by incorporating different views and experiences. This is definitely not an easy task, but inevitable.
A great example for the implementation of such an integrative approach is the ‘International Model Forest Network’. A Model Forest is a fully working landscape of forests, farms, protected areas, rivers, and towns. They are voluntary in nature and aim to sustainable manage a large landscape by building broad partnerships among social, economic, and ecological stakeholders. 35 countries across the globe have adopted this framework in one or more forests, whereas knowledge, research, ideas, and experiences are shared within the network. Model Forests are designed to occupy the middle ground between policy and practice, while successful strategies, also concerning adaptation to climate change, are made available to be adopted outside of a Model Forests boundary.
Julia Ramsauer is a landscape ecologist currently working on the integration of ecosystem services in the Mediterranean region. To keep up with her work, or listen to the latest episode of her podcast, Environmental Science Careers, you can check out for Ecology for the Masses profile at this link or follow her on Twitter @JuliaRamsauer91..