Long-term effects of root plowing on vegetation in the eastern south Texas plains.

Abstract

The long-term effects of root plowing in plant communities in south Texas are not clearly understood. Our objective was to compare plant species composition and diversity on root-plowed rangelands and untreated rangelands. Two rangeland sites that were root plowed during 1973-74 and 2 sites of native, untreated brush were selected on the Santa Gertrudis Division of the King Ranch, Kleberg and Jim Wells counties, Texas. Woody plant canopy cover was estimated with the line intercept method, and density was estimated with 20-X 1-m plots during 1990. Herbaceous canopy cover was estimated with 20 X 50-cm quadrats. Percent grass, lifter, and bare ground coverage were similar on root-plowed and untreated rangelands. Woody plant species and diversity averaged 19 +/- 2 species/ treatment (average +/- SE) and 2.56 +/- 0.15 on untreated areas compared to 7 +/- 1 species/treatment and 1.18 +/- 0.01 on root-plowed areas. Forb canopy coverage on root-plowed sites was about twice that of untreated sites. Huisache (Acacia smallii Ilsey) canopy cover and density were both more than 7-fold greater on root-plowed sites than on untreated sites. Browse species preferred by white-tailed deer (Odocoileus virginianus Raf.), such as colima [Zanthoxylum fagara (L.) Sarg.] and guajillo (Acacia berlandieri Benth.), were absent on root-plowed sites.