Effects of Grazing on Range Area and How Plants Tolerate Grazing
EFFECT OF GRAZING ON RANGE AREA:
Light or moderate grazing has minimal adverse effects. Heavy continuous grazing has drastic effects on rang areas (plants).
- Removal of apical bud will help initiate, growth from axillary buds but (photosynthetic) process will be disturbed. What happens to that whole system for the plant! The whole system is changed; at least 2-3 weeks are required or needed to start the photosynthetic activity at the same stage.
- During active growth season when range areas are heavily grazed, the physiological activities are adversely affected; fewer carbohydrates are provided for root-growth; root elongation will be affected.
- Leaf area is necessary for photosynthesis and it will be reduced by grazing. Reduction in leaf area will result in less photosynthetic availability to different parts of the plant in the long run. By continuous heavy grazing, the plant will lose vigor and will be unable to compete with an ungrazed plant. However, the end result of heavy grazing are these:
- Plant vigor will be reduced
- Reduction in seed production
- Less seedling establishment
- Deterioration in range condition
- An increase of unpalatable spp of the area during the course of time.
- By trampling, soil erosion will increase due to low infiltration. But sometimes this does help in natural reseeding by hoof action.
- Change of spp composition form preferred to the least preferred spp.
- Animals will be feeding on less nutritious spp and their performance is un-efficient.
HOW PLANTS TOLERATE GRAZING:
Following factors contribute to the tolerance or resistance of plants to grazing:
The position of Apical Bud:
If it is located at the soil surface, the plant is more grazing resistance while less grazing tolerant when the apical bud is situated at the height which can be easily grazed.
A high portion of flowering to vegetative stems:
When the flowering shoot is more, the resistance is greater and vice versa.
Delay elevation of apical bud:
Eg Chrysopogon spp keeps apical buds on the ground and elevates them at the time of flowering. So the plants which put the elevation of this bud is dilatory, are more grazing resistant.
Sprout freely from axillary bud:
Those spp where leaves quickly sprout out of axillary buds are more grazing resistant
Those with longer internodes are less grazing resistant because they are easily and quickly elevated and compared to those which have smaller internodes and are more grazing resistance.
Produces special structures:
Those which produce stolons, rhizomes, bulbs, or long awns, etc are more grazing tolerant. While those which do not do so are much more vulnerable.
It means the growth stage. It grazed at an early stage, they are less tolerant and at later stages of growth, they can withstand.
Current growing condition:
The same spp when grazed in drought season it is less resistant while more tolerant in a rainy season. Eg Cenchrus ciliarus – more resistant when plenty of rainfall.
Duration of grazing:
Longer the duration eg Cenchrus ciliarus for one month, lesser the resistance and vice versa eg Cenchrus ciliarus for ten days.
Grasses, on deep fertile soil, are more resistant as compared to those on the shallow poor soil.
Leaf -stem ratio:
More leaf stem-ratio means leaves are more stems are less and less leaf-stem ration means vice versa. In case of more ratios, the plants are less grazing resistant.
Image: Canadian Cowboy Country Magazine
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