Rehabilitation of native grasslands

Restoring natural native beauty to our land

Land that has been degraded by many, often external, factors such as salinity, overgrazing, drought and fire will need rehabilitation to return it to a more productive condition. Whether that final condition relates to greater biodiversity, or high perenniality, or more grazing animals per unit area is not the issue here, it is about restoring an environment to something like its original balanced and resilient condition.

In our experience it is not just a matter of doing one thing alone such as changing the grazing regime or adding seed or removing weeds, but is a combination of several of these factors, all applied in a systematic and planned manner. Planning, or thinking about likely future problems and having a course of action in mind, is vital to success in restoration efforts.

For example, if soil salinity is the major issue for rehabilitation, just closing the gate to prevent grazing is not going to restore soil health or plant vigour. What is needed is a plan to do a number of things, which may include fencing off the worst affected areas, sowing the appropriate types of native grass seeds and planting suitable trees up the slope. It may involve other factors such as control of the worst weeds and incorporation of mulch into the soil through heavy or crash grazing, but what is clear to us is that full rehabilitation of degraded sites is not something that is going to be achieved by just one or two actions accompanied by a lot of hope and trust.

Having said all that, it is important to choose the correct species of grass for revegetation of degraded sites. We emphasise the importance of starting with a grass cover for revegetation as the grasses are the group of plants most capable of providing a full soil cover within a short period of time. This is important as the period after exposure of the soil is the time when soil losses through erosion are at their most devastating and a cover of grass will hold the soil together better than any other plant group. While the final vegetation community may be a forest, the interim step of having a grass coveris a vital step in providing soil cover and microflora build-up which are so necessary for the ultimate success of the forest.

So how do you choose what species to sow?

Often the first step is to find out what grows naturally in the area. To do this it is often a simple matter of finding a local species list which is usually available from your local Natural Resources Management Board or Group. If not from there then ask an informed local nurseryman who has a broad view of the world (not just limited to what they have in stock at the time). Once you have the list of grass species then call Native Seeds and we can advise you which of those species are firstly, available and secondly, likely to succeed in the task of providing a ground cover.
All too often we see a wish list of plant species included in a job specification that may feature up to 30 different grass species. Most of those species are not available as no-one has them under production or indeed they cannot be collected from the wild in the quantities desired. Usually this is for good reasons – such as it being a poor seed producer or not producing viable seed.The next step is to think about the most appropriate method of soil preparation – sometimes, such as after a fire, it is to do nothing at all, but simply to spread seed over the soil surface, other times when the soil is very firm and seed cannot penetrate, it is to do a light cultivation.
Then planning should get intense and deliver a plan that has items included such as soil bed preparation, weed control, sowing times, sowing rates and methods, post sowing treatments to maximise germination, post sowing treatments to prevent weed invasion and processes to ensure that the sown grasses are allowed to grow fully and drop their own seed. Failing to plan for all of these stages will frequently cause failure of the project.
 As seed merchants we are often blamed for the failure of the project as the “seed was no good” or other such excuses. While we take pride in producing good seed (and will supply a Purity and Germination certificate for our main seed lots, if requested), we cannot guarantee a good result in rehabilitation works as there are so many inter-related factors that have an impact on the success or failure of the rehabilitation works.

Rehabilitation of land that has been adversely affected can be a slow and frustrating process. After all why do we think it should take us only 6 months to rehabilitate something that had taken thousands of years to establish in the first place? Our impatience and need for rapid results often makes for inappropriate actions in order to tick off the box called “completion”.

We are not suggesting that nothing should be done, or that it is all impossible, just that when establishing benchmarks for success of the rehabilitation project an assessment of success or failure at 6 months after sowing is not appropriate. It is possible to establish a benchmark for 6 months after sowing that might reflect progress towards an ultimate goal, but it is not the final product at that time. A view that exceeds 1 year is important, and more realistically a view of around 2 to 3 years is needed. Only at that time can success or failure be truly evaluated.