Action on the Ground
LANDSCAPE FUNCTION ANALYSIS
Measuring and Improving Landscape Function and Perennial Grass Diversity
The first step to improving landscape function is to set a clear goal that we can work towards. The goals that we have set for our project sites are:
- Dense perennial grassland with high landscape function and structure.
- ‘High structure’ means the grassland has under-storey, mid-storey & canopy or ground covers comprised of forbs and young perennial grasses as well as mature perennial grasses.
- Deep, (>20mm) stable litter layer with visible fungal attack (in LFA language, this is litter class 7lm)
- Increasing mature perennial grass plants (large bases)
- More than 30 perennial grass species with healthy age structure
Landscape Function Analysis
In this project, we are using Landscape Function Analysis (LFA) to help us judge when and how to use Planned Grazing and pasture cropping to improve our resources. Landscape Function describes the ability of an area to infiltrate water and cycle nutrients into the soil and reduce erosion. Planned Grazing™ and pasture cropping are the tools we are using to increase landscape function. A critical, but sometimes overlooked aspect of grazing management systems is a recovery plan. A recovery plan is based around the time it takes for the highest succession (desirable) perennial grass to recover and produce fresh yellow litter. In this project, we will plan recovery and use LFA and observation to look for the signs that the best perennial grass has fully recovered and signs that the site needs to be grazed.
Landscape Function Analysis was developed by Australian scientists, David Tongway and Norm Hindley (see website) . It uses visible indicators of plants, litter and soil surface condition that gauge how effectively a landscape is infiltrating water, cycling nutrients and keeping the soil stable, healthy and productive. Although it was developed originally for mine site and Rangeland rehabilitation, we are finding it a very useful tool for this project and are setting aside ideas for its further development should that become appropriate.
The following sections provide an example report similar to the reports received by the project sites.
The following table provides an example of a Landscape Function Report for Site A, it shows the target scores for Soil Stability, Water Infiltration/Runoff and Nutrient Cycling that this site is trying to achieve. Soil Stability is the ability of the soil to withstand erosive forces, and to reform after disturbance. Infiltration/Runoff is how the soil partitions rainfall into soil-water (water that is available for plants to use), and runoff water which is lost from the local system, or may also transport materials (soil, nutrients and seed) away. Nutrient cycling is how efficiently organic matter is cycled back into the soil.
These scores indicate that Site A’s soil surface is:
- Quite stable and only slightly vulnerable to erosion.
- Water infiltration is moderate but moderate to high rainfall events will result in runoff.
- Nutrient cycling is quite low. The organic matter is not being cycled back into the soil very efficiently.
- The litter class 5ls means that there is not 100% ground cover, the litter is local (from plant material at that spot) and the current decomposition is slight.
To increase these scores, the area will be monitored using strict criteria until it has been judged that enough litter has been grown to move the site towards the litter class target of 7lm. This litter class means there is 100% ground cover with litter greater than 2cm deep and displaying active fungal attack. To make this happen, he needs a lot more plant material (refer to the photographs below). To make this happen, livestock will be excluded from the site until such a time as the best perennial grass plants have regrown large amounts of fresh, yellow coloured litter.
The area will then be grazed at approximately 5000 dse/ha for a brief period, generally around a couple hours, until the litter within the perennial grasses has been pushed onto the soil surface so that as much of it as possible can decompose actively. This high stock density is one way of applying the tool of animal impact. The area will then have all animals excluded until the best perennial grasses have regrown large amounts of fresh, yellow coloured litter.
All Project Sites
There are 13 Project Sites involved in this project. The following table and graph shows all of the LFA scores of the project sites.
The table below shows the LFA score alongside a photograph taken of part of the monitoring transect. Sites A and H are from the project and represent the best and the worst scores. The final site is an example of what the soil surface looks like when the LFA score is really low.
When you look at the photos, remember that the higher the score, the more resources are being retained on the site and when the scores drop, it means that the site is not retaining soil, infiltrating water or cycling nutrients as it should and that this means that the pastures are not growing as well as they could be and that they are more vulnerable to difficult weather conditions.
Litter class: 5ls
Litter class: 6ls
EXAMPLE OF POOR LANDSCAPE FUNCTION
Litter class: 2ln