Microclimate, Fire, and Plant Production in an Illinois Prairie

Abstract

Decomposition and effects of fire on microclimate and plant production of a Tall Grass Prairie were studied in east—central Illinois. After two years simulated litter samples in contact with soil lost 64% of their initial weight. Burning caused a 2—3 fold increase in production and a ten fold increase in flowering. Application of mulch, lowered flowering rate; response was proportional to thickness of mulch and length of time it was in place, Artificial shading of burned areas under green—house frames lowered flowering rate. Burning or clear cutting vegetation increased percent N and P in May foliage. A May application of N fertilizer increased flowering and dry matter production. Nutrient release from ash had no effect on flowering or production. Root production was similar on burned and Burn 3 areas; a turnover rate of 0.45 was calculated. Calcium content of roots in May increased after fire and N content decreased. Temperature from —5 to +50 cm and light intensity from 0 to +50 cm were higher on burned than Burn 3 areas. Maximum soil surface temperatures occurred three months earlier on Burn 0 than Burn 3 areas. Soil moisture was never severely limiting to plant growth. Growing season microclimate measurements at 50 and 200 cm were combined into a microclimatic index, which allowed comparison of the microenvironment of three burning regimes. Total flowering was proportional to duration and degree of favourable microclimatic conditions from May to mid July.