Animal Impact

Animal impact is all the effects that are associated with herding animals, including:
  • Trampling of standing vegetation
  • Disturbance of exposed soil surfaces
  • Dunging
  • Urination
  • Salivation
Animal impact can be implemented in three forms:
  1. Low animal impact
  2. High animal impact
  3. Herd effect
Low animal impact
Regardless of its size, a herd or flock of animals that can be continuously held in a paddock for weeks, or even months, is delivering low animal impact.

At low stock density animals walk carefully upon the land.  They walk around bunches of grass, rather than through them.  The photo below shows the effect of low stock density.  You will notice that the old grass clumps have tracks through them where stock have walked.  There is no incentive for the animals to walk into (or onto) a clump of grass.

High animal impact
High animal impact comes about when herds or flocks are joined together and sequentially move through a number of divisions of land.  If animals can only remain in a fully recovered paddock for a matter of days, they are delivering high animal impact.

Depending on their density, there will be significant behavourial change in the herd or flock.  For example, animals will tend to be in each other’s ‘space’ more.  They will become less careful about where they walk, and as a result, they will trample more material onto the soil surface, thus completing the second phase of the mineral cycle.  The photo below shows how a big mob of sheep were able to trample and lay down a substantial litter cover.  If you look, you can see that new growth is appearing through the litter cover.

The photo below is a close-up, showing the vigor that new grass has developed when protected by trampled litter.  It is simply ‘bouncing’ out of the ground.

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