Biodiversity & Ecosystem Health: Exploring Western Scientific Concepts with Rachel Holt

aerial photo of old growth forest

In the final instalment of our Indigenous Law in Language blog series, we continue to explore how we can bridge the languages of science and Indigenous law together. Dr. Rachel F. Holt works in conservation biology and land management. We sat down with Dr. Holt to discuss some of the concepts western-trained scientists use when discussing biodiversity and ecosystem health.

Please introduce yourself and tell us a little about the work you do.

I am an ecologist who has lived and worked in BC since 1992, when I arrived to do my graduate research in landscape ecology. For the last 25 years I have run my own one-woman consulting company, focusing on landscape planning, ecosystem-based management, old growth forests, policy development and working with First Nations to pursue land management and governance goals.

Can you explain what ecosystem health and ecological integrity mean, and why they are important?

Typically, ecosystem integrity and ecological health are quite synonymous concepts. In general, they both suggest an ecosystem where all the natural attributes – species, communities, ecosystems, natural processes – are expressed within the normal historic range. There isn’t a single fixed definition of course because ecosystems, even in BC, are wildly different from each other (from desert to temperate rainforests) and are dynamic systems that change through both time and space. 

Both concepts, to be meaningful, are really about an ecosystem not being significantly impaired or degraded from its natural state. This doesn’t mean that the system must be pristine of course – there is nowhere on earth that is not impacted by some elements of the industrial footprint, especially when thinking about climate change. But, to have ecological health or ecological integrity all the species must be present, across their original distribution and in reasonable numbers so that populations are not only not at risk, but are robust and resilient to loss. 

This requires the habitat for species to also be present in a distribution and form that is similar to natural conditions over a landscape. If you think about a forested landscape – the amount of old growth forest present in a healthy ecosystem should be not so different from natural systems where species, communities and processes such as hydrology have been disrupted. Similarly, in healthy ecosystems the water supply in streams and rivers must be at a level that historically has supported salmon entering the creek and spawning. When water levels drop outside the natural range consistently, then salmon populations decline or are lost rapidly. 

Why is this important? 

Science has known for a long time that the industrial footprint of humans is systematically degrading ecosystems. Degrading means pushing past thresholds of change where natural processes and elements become non-functional or lost. The list of activities that humans impose on ecosystems is long. Humans have degraded ecosystems literally from the ground up, and there are endless research studies on everything from soil and water degradation, to species loss, to the intricacies of climate change. On a really basic level, depleting soil, water and changing the climate already poses a significant threat to human existence in many places in the world, and is today having tangible impacts here in BC where future forests are being fertilized from helicopters because of soil productivity loss, and where many areas of the province face significant drought. Our current approach is not sustainable.

Climate change is probably the most extreme version of ecosystem degradation – pushing the levels of greenhouses gases outside their ‘normal’ or historic range is already causing grief on a global scale, and will without doubt continue to do so going forward.

We need ecosystem health as a mandate because the industrial approach has failed ecosystems, and human communities. Land management decisions are made based on cost and profit, not based on whether there will be enough cool water in the streams to maintain salmon populations. BC is one of the most intact places in north America, and yet we are moving daily further from having healthy ecosystems as the list of endangered species continues to grow, and concerns about water availability are very real in many areas of the province.

What do we mean by biodiversity and ecosystem functions?

Biodiversity simply means all living things and all their interactions. Everything that's out there in nature. Science has named around 1.5 million species but estimate there may be something surpassing 8 million species on the earth. Imagine all that biodiversity, “those things” out there living in their worlds – that is ecosystem function. Think worms and many other microscopic species, living their lives and yet being central to such basic functions as pedological processes, creating soil. Think beavers being ecosystem engineers and creating entire aquatic ecosystems that support hundreds of other species. Think woodpeckers chipping out holes in trees and making homes for species as diverse as bees, snakes, flying squirrels and chickadees. Species all interact, just like humans do. We need to be humble about ecosystems and understand that we don't know everything, and we never will. We need to fundamentally have a regime that maintains biodiversity because biodiversity maintains all the functions of life on Earth.

Can you explain the concept of resilience? 

The concept of resilience is the ability of a system to either resist change or bounce back after change.

Ecosystems are always subject to stresses, short-term stresses and long-term stresses over time. Resilience is the ability to retain the essential structure and function of the ecosystem even with stress. If an ecosystem is not resilient, the system can undergo a “regime shift” and lose the ability to produce the ecosystem services and functions we're used to. For example, an old growth forest in coastal BC may shift into a red alder forest after harvesting, and it may be difficult to move it back onto a trajectory of recovery to conifer forest. Another example is disturbing the soil in a native grassland that naturally is a diverse community of species, and then knapweed or scotch broom takes over and the former grassland becomes a monoculture of invasive species that is very difficult to restore to a native grassland. 

Ecosystem health and resilience are related concepts: noting that ecosystem health is not the same as forest health. Some people make this mistake – but of course, disturbances such as insects and disease, and fires, are natural parts of the forest. Humans imposing management strategies that attempt to wipe out these natural processes and make a “healthy forest” tend to make the system more vulnerable, or less resilient, in the long term. An example of that today is the effect of forest policy creating simplified landscapes through wide-scale application of glyphosate to kill deciduous tree species. This profit-based action, combined with fire and cultural burning suppression, has led to a massive vulnerability of BC forests to large scale fire. This is not a healthy, or resilient situation.

The importance of resilience will be seen a generation down the road, when my kids are adults. If we are careful and thoughtful now, healthy and resilient ecosystems can still be providing all their services - keeping the water clean and cool, maintaining natural species diversity, and performing all they do to maintain themselves and natural communities.

Why is it important that we talk about the language we use?

I have two answers to the question. 

Language is incredibly important to try and capture this phenomenal diversity of life and how it interacts, and to figure out ways to maintain it. Getting the right language and the right concepts are very important. If we want to manage something well, we have to be able to talk about and understand natural systems. We also have to understand the extent to which we don't understand everything, all of which requires complex language.

I also think that language often undermines us. As scientists, we're so focused on language that values and actions get lost. How many science papers exist on ecological integrity? There are hundreds and hundreds debating language, debating whether it's this or that, driving down to a very reductionist way of looking at the world and arguing in papers back and forth arguing about terms and what they mean. All the while, that same ecological integrity is declining around us. 

Language can be a huge barrier. Language can help us, and it can hinder us. But looking for commonality in the values is what we need to do to try and sustain life on earth as we know it.

Dr. Rachel F. Holt, in conversation with Whitney Lafreniere Vicente, West Coast Environmental Law. This interview has been condensed and edited for clarity.

Top photo: Province of British Columbia (Flickr Creative Commons)

Indigenous Law in Language Series

Whitney Lafreniere Vicente, Staff Lawyer
Dr. Rachel F. Holt