Rewilding Abandoned Eucalyptus Plantations

Our Project Plan

The practical rationale for this project is to develop our low-impact methodology for eradicating eucalyptus from plots to allow for natural regeneration and the recovery of native forests. The goal is to see the forest improve in terms of habitat structure and biodiversity and its former function alongside the Mira River as a crucial ecological corridor.

To achieve this, firstly we are running a pilot intervention on a 46.5 ha plot of riparian area in the municipality of Odemira on the Mira River, containing approximately 20 ha of eucalyptus stands. Using this as an experimental plot will allow us to test and improve techniques, whilst serving as an example of ecological conversion of eucalyptus stands to showcase to other potentially interested landowners. 

Here are a few techniques that we are considering at the moment:

• Arborism pruning: to cut down tall eucalyptus trees so logs do not simply fall down on top of young regenerating oaks. Instead they will be chopped and lowered in a controlled manner. 
• Horse logging via existing paths: to transport tree trunks out of the heart of the forest without using heavy machinery and causing too much damage to vegetation. 
• To exhaust the eucalyptus stumps, there will be frequent follow-up control of new shoots from the pruned stumps until resprouting eventually stops.

Since this first plot is bordering the river, we will care for the restoration of the riverine forest too. In this case, that means eradicating a clump of the invasive Giant reed, Arundo donax, that exists in a small area. We will have to dig out all the rhizomes and roots to prevent further invasion. We will also immediately install an erosion control structure with wooden poles, planted with bundles of the native reed, Phragmites australis.

See this Project Management Plan for an extensive description of the assessment and implementation plan. Included in this document is a monitoring plan and evidence on the state of the habitat prior to this intervention. The process of gathering a baseline scenario has involved: 

• Pre-study on the current conditions of the pilot plot 
• Field-assessment of flora 
• Installation of camera traps in key crossing points of the property for wildlife. 
• We are also looking into testing a soundscape monitoring method to capture 'before and after' samples. Additionally, we will measure environmental parameters such as soil organic matter, soil moisture, air temperature amongst others.

All this data is to be analysed and evaluated to understand if we are achieving the expected results, or if not, to learn and adapt our strategy if necessary whilst communicating the outcomes. 

In a more mature phase of the project, we aim to carry out on-site training and knowledge transfer activities for interested representatives of any stakeholder groups and to expand the project to more plots alongside the Mira River. 

Rewilding Abandoned Eucalyptus Plantations - VLOG

Watch our Conservation Site Manager Teresa explain more about this intervention from the ground in southwest Portugal, where she joins plant specialist Udo for an aquatic plant survey.

Project Discussion

Hear the in-depth background of this project and gain insights on what we're planning for the restoration of the ecological corridor in the Mira Basin.

Project FAQs

What will happen to the removed eucalyptus logs?

The current plan is to sell the removed logs for its common value - timber. Our first landowner has agreed that this income will be reinvested into the project, contributing to the financial sustainability of the intervention. Another option we are keen on exploring for the future is the production of biochar, which could be put back into the land and help regenerate soil.

Will you be planting trees to bring back native forests?

We are giving nature a shot at doing it on its own terms, because natural regeneration does it better than us. In particular, when there is a strong seed bank in the vicinity or the process has already started. Luckily, this is the case we find in our first plot. We will consider, however, if the circumstances are not so favourable. For example, the restoration of the riverside forest often requires planting riparian trees to factor in the natural competition with fast-growing grasses or even invasive species.

How long do we expect the natural regeneration process to take?

The time taken by nature to regenerate will vary greatly from place to place, depending on the baseline conditions. In the case of our first plot, this process is actually quite advanced, in comparison to the average timescale, since we are working with a long abandoned plantation of eucalyptus. To illustrate this, one can find many Portuguese oaks, cork oaks, ashes, hawthorns, wild strawberry trees and Iberian wild pear trees growing there, some higher than several metres in height already. There are also unpredictable factors, such as climate change, that make estimating the growth of our forest difficult still. Nevertheless, we can estimate that in 50 years time (or probably less), this first plot will look very different, resembling much more of an oakland.

Could you use animals to control the vegetation and prevent fire in the native forest?

Our pilot plot is well protected from fire entry points as it’s mostly surrounded by low-fire risk farmland. Fire behaviour and prevention analysis is a must do in Portugal, with each plot usually having its own plan, defining ecological discontinuities in vegetation so potential fires can be quickly controlled in the most strategic sites. However, the most effective way of controlling vegetation is by far herbivory, either by domestic animals (including neighbouring herds of grazers) or by wild animals, which is the most interesting for us in the context of rewilding. A deeper assessment of the possibilities for more wild herbivorous animals in this region is underway, but for now, we know we’re contributing to increasing the habitat for these species by reconverting abandoned eucalyptus plantations. We’re not introducing koalas to Portugal or other Australian species that are the only animals who feed on this genus. Not only is this forest structure and composition more fire resilient in itself, the whole ecosystem is, since it can host more flora and fauna species, boosting a more complex food chain. For example, there have been sightings of red deer (Cervus elaphus) making a return to this area, which is exciting for both wildfire prevention and forest restoration in these conditions.

Can you ringbark the eucalyptus trees or is that too labour intensive?

It is possible to ringbark eucalyptus and there would be some advantages in terms of saving costs and labour when carrying out the work to cut and transport the logs. However, new shoots will appear from the base of the stump since eucalyptus is a re-sprouting species. Here are the reasons we are not considering that as an option:

In the local context where eucalyptus plantations have average tree densities of around 1000 stems/ha, we would leave a very large amount of tall standing wood (which would eventually topple onto something). Since our main goal is to assist natural regeneration in the understory, this would later become counterproductive for the survival and longevity of emergent oaks, other native trees and slow-growth bushes. Additionally, the fire risk associated with eucalyptus plantations would not be addressed. That's why a main part of our intervention is to find secure and efficient ways of taking down tall eucalyptus trees and removing them from the forest whilst leaving some deadwood, aligned in contour on the forest floor. The other important challenge is about controlling the re-sprouting of eucalyptus. This is something that would have to happen even with ringbarking.