Burn Severity and Soil Type Affect Oak Growth and Nutritive Value.

Post-fire shifts in species composition and growth driven by alterations in resource availability can affect the quality and quantity of forage available to livestock and wildlife that browse in these areas.  Therefore, we designed an experiment to test the effects of fire severity and soil type on the growth and nutritive value of re-sprouting Quercus stellata (post oak) and Q. marilandica (blackjack oak) growth and nutritive value in a mixed pine-oak forest in Bastrop State Park, Bastrop, Texas, four years after a naturally occurring wildfire.   In July 2015 we measured re-sprout heights and diameters and collected leaf samples for N, C, and protein precipitable phenolic (PPP) analyses. We took measurements in three soil types: 1) Edge, 2) Jedd, and 3) Padina, within two burn severity classifications: 1) moderately and 2) severely burned.  We replicated measurements in each soil type/burn severity combination three times for a total of 18 plots.   Blackjack oak re-sprouts were taller and had leaves with greater C and PPP concentrations than post oak (P ≤ 0.05).  The protein binding efficiency of post oak PPP was greater (P ≤ 0.05) though, as its PPP bound as much protein (P ≥ 0.05) as that of blackjack oak.  Post oak leaves also had greater amounts of nitrogen (P ≤ 0.05) than those of blackjack oak.  Leaves from both species meet small ruminant daily maintenance requirements with crude protein averaging 9.26% and 10.21% for blackjack oak and post oak respectively.  Although plant density did not differ (P ≥ 0.05) between burn severities, re-sprouts of both species were taller and had larger (P ≤ 0.05) diameters in severely burned plots.  Reduced growth in moderately burned plots may be due to increased competition with loblolly pine since we encountered a greater number of pine individuals in moderately burned areas than those that were severely burned.