Case Study By Sean Altern – Consultant: Biodiversity Conservation Services
Developments often coincide with a certain level of unavoidable damage caused to the surrounding environment. Fortunately in most cases much of this damage can be mitigated and rectified through proper planning and professional care. Whilst there are many ways in which vegetation rehabilitation can be successfully undertaken, NCC’s approach is based on a solid understanding of the specific vegetation and environment. We focus especially on the drivers or, ‘those forces that cause the vegetation to exist there in the first place’ and aim to utilise these. Where possible, NCC taps into these systems and with a little bit of added help enables them to naturally restore sites.
It is in some ways a “minimal approach”, which is slower than other methods and it might appear as though not much rehabilitation is being done. NCC however believes this approach to be more ecologically appropriate in the long run, as it results in the local indigenous species re-emerging in natural patterns and assemblages through natural succession.
For a recent project, the key drivers of the area’s vegetation were noted to be soil type, soil water availability, wind and animal dispersed seeds. We utilised these ‘driver’s by installing biodegradable silt nets which would not only protect the exposed soils from the initial threats of erosion, but also catch many wind-blown seed-types as well as added moisture. This creates microclimatic, more shaded and protected conditions at the base of the net to assist in seed establishment. The biodegradable materials (made from repurposed invasive alien plants) are especially advantageous as it means no trampling of new growth, which would occur if synthetic materials were used, and which would eventually require removal.
By utilising dead, seedless branches of cut invasive trees and installing these around the site, we encourage birds to perch and through their droppings, seed of other indigenous species (apart from wind-blown types) will be deposited into the area.
Another trick we used was to create piles of packed brush which again provides shaded and protected microclimatic conditions for seed establishment. The brush also serves as potential homes to attract species such as field mice to the site which are responsible for the dispersal of local Wildenowia (restio like species) seeds. Essentially, we put measures in place which will allow and encourage the drivers (creators of the vegetation) such as wind, birds and rodents seed dispersal agents to replant the site for us.
To give the vegetation recovery a bit of a kick-start, we also replanted ‘search and rescued’ species, those indigenous plant taken from the site before it was cleared, and positioned them into nodal groupings which will provide support for each other and eventually spread throughout the site.
Whilst this approach at first might not look as great and instant as a site where vast numbers of plants are brought in and the area are ‘greened overnight’; the exciting part is knowing that the site is (along with an invasive species management programme) protected from further degradation due to the measures put into place and is slowly but surely being reclaimed and fixed by nature and the drivers that originally created it.