A major challenge in restoration ecology is the widespread belief that there is a correct natural community for any given location, and that identifying it is the first step in recreating it. 1/6
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In ecological theory this assumption dates back to the ecologist Clements who proposed that there is a 'climax' state that the vegetation in any particular location will reach. Most ecologists now reject this simplification but it nevertheless persists. 2/6 https://en.wikipedia.org/wiki/Frederic_Clements
The problem is that in fact there are multiple potential stable states for any given set of conditions. Even for a question so simple as 'should there be trees' there is often room for uncertainty. See also https://www.sciencedirect.com/science/article/pii/S1360138519303036 3/6
We even have evidence that in more productive environments the number of potential states grows, increasing the uncertainty about what should occupy any particular location. 4/6
Ultimately this requires humility in restoration ecology and a recognition that nature is a process, not an end point. This was one of the key messages arising from the work of historical ecologist Oliver Rackham (among others). 5/6
Beware when anyone declares that their favourite habitat is the right or necessary state for a given location. Even if it was there in the past, it might not be the end-point now or in the future. 6/6
truth! - habitats come and go — due to natural & human-made reasons primary/secondary succession as change writ somewhat small — evolution as change writ large —a function of time and for now the age of humans; old eco-case studies Kaibab Plateau, Ducktown, methyl mercury in Japan, DDT everywhere…
I would partly disagree. The evidence for multiple stable states is often not robust enough to use this framework for prescribing management actions. 1/7
We don't disagree that much because I've never said that ESS should be the basis for decision-making, only that we can't assume that we can identify the 'correct' state. Yes the savannah/forest dichotomy is more complex but it was only a short thread 😉
Okay ;) but if there IS a ‚correct‘ state and we fail to recognize it, as has been the case in the forest-savanna-bistability assertion, then we make badly informed management decisions.
The problem is that we often misinterpret prediction uncertainty in ecological models as evidence for overlapping environmental conditions between two or more ecosystem states, when in fact this uncertainty can be greatly reduced by better models and data. 2/7
The graph from the Pausas and Bond paper you posted is an example: It shows overlap along one variable (annual rainfall), but most people would agree that the distribution of forest and savannas is also influenced by other environmental factors 3/7
A string of recent works shows that when these factors are considered and better data is used, the remaining overlap between forest and savannas is minimal, refuting the hypothesis of widespread bistability and pointing to a predictable endpoint in this system. I include some references below. 5/7
A similar problem occurs when the observation time span in experiments is too short to allow deterministic end points to be reached. For example, when the monitoring time series of phytoplankton biomass is extended, it turns out that phytoplankton is linearly related to nutrient concentrations 6/7
not just climate change either. Nitrogen is driving so many habitats towards a high nutrient status, with all the attendant consequences for ecosystem health and complexity.
All the comments here are from people and while it's good to hear so many different opinions I think we should include the herbivores and mega-herbivores, with their 250 million years experience of managing vegetation, as an essential part of the conversation.
The vast majority of nature photos show vegetation that hasn't been influenced by mega-herbivores and it's the same in real life pretty much everywhere.
It's always the first thing I look for and the reason why I advocate for restoring their migrations in Europe.
When I was in grad school, the emphasis was on restoring the PNW of the USA to the condition of the 1850s, when Euro american settlers arrived. Talk about arbitrary. This fundamentally shaped my approach to restoration, which I jokingly refer to as "nihilist restoration" (1/2)..
The fate of all species is extinction, no system is stable over any real timescale. Restoring to the past at any point was basically hubris on the last of humans. I love, and teach and preach the RAD (resist, accept, direct) framework of landscape management. https://ui.adsabs.harvard.edu/abs/2020usgs.rept...20S/abstract
I agree, but that does not mean we cannot try identify the range of natural communities that would occur in the absence of industrial human influence. Because 'natural' can encompass a range of states does not imply we should do away with the notion in restoration.
I once held that opinion, but now, in the age of climate collapse, in which we cannot be sure what species a given area will support in the future, I am of the opinion that the objective should be to attempt to preserve existing biodiversity and that which we know was there in the historic past.
Really you have said it all. The idea of a correct state underpins the idea of rewilding, that nature will find its own ideal. All our lowland heath is human-created and scarcely meta-stable
I agree in part. Yes, left to its own devices (perhaps with a helping hand where necessary) nature will finds is own ideal given the prevailing edaphic conditions and context. Yes, our lowland heaths are human-created and therefore dependent on continued intervention/management for their existence.
But the idea of a correct state does not underpin rewilding. It is a dynamic process wherein nature calls the shots. Any project calling itself "rewilding" where there is a defined end-state is not rewilding. Simplified, rewilding is giving nature the space and time to determine its own trajectory.
Is Rhododendron permitted in a rewilded landscape? If not, then what else is barred, and who decides?
The temperate rainforest ideal appears to be aiming at a wild state, but it always implies 'native species' only
I see “cutting scrub” in your profile so be my guest… Hackney at as much Rhododendron in the UK as you like. That’ll definitely keep you busy until you die. 😉
Rewilding does happen, but not by design. If a project is designated as rewilding then it will definitely have a target, usually broad-leafed woodland. You can't get funding without a project plan
That target is a self-sustaining, self-regulating, dynamic and fully occupied trophic ecosystem. That can be the plan surely? The actual ecosystem type doesn’t need strict definition. Our work is global. Rewilding can apply to any modified/degraded ecosystem not just broadleaf woodland.
I can agree with that, but that is so broad that every brownfield site fits the definition. A hillside of lowland calcareous grassland transformed into hawthorn scrub fits. If I am rewilding a site then that implies making choices and blocking some routes
No you have this the wrong way round. Rewilding is about letting nature create its own state, without fixed outcomes. Restoration and conservation are much more predicated on the 'correct state' and rewilding is a reaction against them. Although admittedly many seem to have got this confused.
I agree with you in principle, but this definition of rewilding is not used consistently. The term has also changed in its meaning quite substantially over the last 20+ years.
Precisely why we were asked by the IUCN to work on a unifying definition and set of basic guiding principles. see: https://doi.org/10.1111/cobi.13730 ...one step towards the IUCN guidelines on rewilding.
I have known some parts of reserves that have escaped management control. Your average gravel pit does the job well if left. But rewilding examples somehow avoid these, concentrating instead on broadleafed woodland with managed grazing.
There are always compromises and that is fine but it is always good to keep the objective in mind IMO.. even if we can't do it perfectly yet. Some have confused the interim or compromise versions of rewilding with the ideal.. others have found a new way of saying 'maintain the landscape'.
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This is why we discuss ecological complexity as an aim for restoration rather than target communities
https://doi.org/10.1111/ecog.05780
It's always the first thing I look for and the reason why I advocate for restoring their migrations in Europe.
The temperate rainforest ideal appears to be aiming at a wild state, but it always implies 'native species' only