Improving revegetation success using mulch on a semi-arid prairie in southern Alberta, Canada

FEDERICO MOLLARD; M. ANNE NAETH; ANAYANSI COHEN-FERNÁNDEZ

Buenos Aires

Congreso; IV Congreso Iberoamericano y del Caribe de Restauración Ecológica (SIACRE2015); 2015

SIACRE

Seedling establishment and early vegetation performance in semi-arid prairies under reclamation can be facilitated or inhibited by mulch due to its effects on seedbed and field conditions. A field experiment was established to determine if straw and hay mulch facilitate or inhibit revegetation in an abandoned irrigation area in mixed grass prairie of southern Alberta, Canada. Soil was tilled, the seedbed prepared through harrowing and plots were broadcast seeded with a mix of native species. Hay and straw mulch were applied at two rates (300 and 600 g m-2). Seedling establishment, plant performance and cover were assessed during the first three years. Total seedling emergence and that of Elymus trachycaulus, Linum lewisii and Astragalus canadensis were higher with low straw and both hay mulch rates relative to bare ground. High straw application rates were inhibitory and hindered Bouteloua gracilis emergence. E. trachycaulus and L. lewisii had a higher cover in mulched treatments than in bare ground. B. gracilis had a high cover in bare ground and disappeared or behaved as a subordinate species in mulched treatments. Mulch strongly suppressed B. gracilis seedhead production. Our results justify the use of low rates of straw or hay mulch for prairie reclamation as mulch represents an inexpensive method to improve seedling establishment. A finer textured mulch such as hay was a more conservative option than straw as it facilitated seedling establishment even at high rates. Mulch should be applied with caution when the reclamation target is a community dominated by B. gracilis.