Karin Didderen1, Tjisse van der Heide2
1 Bureau Waardenburg, BESE, Culemborg, The Netherlands
2 Royal Netherlands Institute for Sea Research, Texel, The Netherlands
The search effective nature-based restoration solutions that work
To test the applicability of biodegradable matrix structures for ecosystem restoration, an international consortium consisting of developers, scientists, manufacturers and end users investigated the efficiency of the BESE elements to restore e.g. peat, saltmarsh, seagrass and shellfish reef habitat across Europe over the past 4 years. The results show that nature-based restoration solutions that mimic properties of existing ecosystems can work effectively if applied at appropriate locations, proper spatial scales and a suitable manner of construction.
Salt marsh and seagrasses - top or bottom
For multiple ecosystems and restoration-needs the matrix structures work well on a small scale. Since we have already conducted pilot experiments for several years, we were able to scale-up, and to study mechanisms behind the success and the limiting factors. For example, in salt marsh restoration we use a 3-layer structure on top of the intertidal mudflat in salt marsh restoration. Experiments demonstrate that salt marsh transplant survival and growth are strongly facilitated in areas with strong waves and mobile sediments by below-ground 3-sheet high BESE units, which simulate sediment stabilizing root mats of established vegetation. Moreover, we found that the transplants profit even more from above-ground BESE units that i) simulate wave dampening as is normally provided by larger well-established dense patches of plant stems, and that ii) trap both sediment and plant seeds, which further facilitate salt marsh development. This tremendously increased in survival of out-planted tussocks of Spartina anglica and S. alterniflora and at the same time enhanced natural recruitment of pioneer plant species like Salicornia. We also learned that the outgrowth of Spartina anglica continues over time and results are often comparable across sites.
The global seagrass experiment, with MERCES partners, included similar experiments on seagrasses across different climate zones (tropical and temperate seagrass). Results are showing that for this habitat, below-ground structures that mimic root mats facilitated seagrass transplant survival the most by stabilizing the sediment.
From science to practise
We are currently transferring the BESE restoration technique into field applications, for example in re-establishing Spartina patches in an estuary with a lack of natural accretion (Figure 1). Furthermore, the structures were applied in a Coastal Defence Scheme in the UK where salt marshes were transplanted (Figure 2). In 2020, we will release an implementation guide for restoration practitioners that will show the best practises for individual ecosystems. At the same time, we have new pilot studies across the world testing applicability in restoration of e.g. shellfish reefs (Figure 3A) mangroves (Figure 3B), riverbanks, and dune vegetation.
Figure 1. BESE restoration technique: re-establishing Spartina patches in an estuary with a lack of natural accretion
Figure 2. BESE restoration technique applied in a Coastal Defence Scheme in the UK
A)
B)
Figure 3. New pilot studies across the world testing applicability in BESE restoration technique: A) shellfish reefs B) mangroves
Learning from failures
As with all innovations, learning from failures is accelerating the learning-curve. We found that at exposed intertidal locations with very harsh conditions due to strong waves and mobile sediments, it is difficult to really kick-start restoration, even with BESE-elements. Although the structure is quite strong and was able to withstand several hurricanes in the USA, it failed to work for restoration in those locations. At the same time, when conditions are benign, a technical solution to stimulate plant or reef growth may be unnecessary. We now conclude that it is in intermediate exposure situations where BESE proves most valuable to increase restoration success.
From science to business
Apart from the scientific results, we celebrated some business successes. In 2019 we were able to commence a start-up company BESE Ecosystem Restoration Products (https://www.bese-products.com/). The goal is to aid restoration of ecosystems worldwide through knowledge transfer and the application of new innovative technical solutions and to achieve successful restoration without the use of permanent artificial materials such as plastic. We now have 50 projects on 4 continents in 11 ecosystems, some through the MERCES network. We learned that the challenge to help nature restoration with the help of nature itself is a way forward that will pay off. BESE director Wouter Lengkeek “Our inspiration when working with our “restoration-building-blocks”? Engaging people. A great way of reaching the restoration goal, generating new ideas and transfer knowledge all at the same time.”
Partnership
The BESE-elements have been developed by Bureau Waardenburg, NIOZ, Radboud University of Nijmegen, Enexio and Rodenburg Biopolymers.
