Post seasonality grazing of native grasslands after mid October does not harm the senescent lead tillers that produced seed during the growing season. Unquestionably, all the other tillers; the vegetative tillers, the secondary tillers, the fall initiated tillers, and even the next spring initiated tillers are severely negatively affected by post seasonality grazing after mid October.
Vegetative reproduction of grass tillers is the dominant form of grass recruitment. Very few grass seedlings exist in grasslands. All grass vegetative tillers live for two growing seasons. The secondary vegetative tillers will be the future young lead tillers. They store carbohydrates for winter survival only during the winter hardening period of mid August to hard frost.
Winter dormancy in perennial grasses is not total inactivity, but reduced activity. The crown, portions of the root system, and some leaf tissue remain active and maintain physiological processes throughout the winter by using stored carbohydrates. Cool-season grasses continue leaf growth at slow rates during the winter.
Some tillers with low carbohydrate reserves do not survive until spring. The rate at which plants respire, or use, stored carbohydrates during the winter is affected by the amount of insulation standing plant material and snow cover provide from the cold winter air temperatures. The greater the amount of insulation, the more slowly the plant draws on its carbohydrate reserves. The lower the quantity of insulation, the greater the rate of respiration and the greater the chance of depletion of the carbohydrate reserves before spring, causing tiller death called “winter kill”.
These carryover tillers that survive are always low in carbohydrates the next spring. Grass new leaf growth depends mostly on the carryover leaves that regreen in the spring and provide the crucial photosynthetic product for most of the new leaf growth in the spring.
If those carryover leaves are grazed during the previous fall, that grassland will lose those new leaves that the missing carryover leaves would have produced which greatly decreases the quantity of forage that would have been produced the following growing season.
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