Wildlife Habitat Quality (Sward Structure and Ground Cover) Response of Mixed Native Warm-Season Grasses to Harvesting

Abstract

Agricultural intensification in America has replaced native warm-season grasses (NWSG) with introduced forages causing wildlife habitat loss and population declines for the northern bobwhite (Colinus virginianus) and similar ground-nesting birds. Reintroducing NWSGs onto managed grasslands to reverse grassland bird population declines lacks information about appropriate multipurpose management. Post-season nesting habitat quality of mixed NWSGs (indiangrass (IG, Sorghastrum nutans), big bluestem (BB, Andropogon gerardii) and little bluestem (LB, Schizachyrium scoparium)) responding to previous-year(s) harvest intervals (treatments, 30-, 40-, 60-, 90 or 120-d) and duration (years in production), were assessed on late-spring-early-summer re-growths. Yearly phased harvestings were initiated in May on sets of randomized plots, ≥90-cm apart, in five replications (blocks) to produce one-, two-, and three-year old stands by the third year. Sward heights and canopy closure were recorded a day before harvest, followed a week after by visual estimates of ground cover of plant species and litter. Harvesting increased post-season grass cover and reduced forbs following a high rainfall year. Harvested plot swards showed no treatment differences, but were shorter and intercepted

Harvesting Effects on Species Composition and Distribution of Cover Attributes in Mixed Native Warm-Season Grass Stands

“…It is likely that the dominant perennials in the more frequently harvested plots posed less obstruction to wind-borne seeds of BS and other perennials. This was consistent with earlier reported lack of differences in percentage of ground cover for grasses in the early-season growth, attributable to previous harvest intervals [34]. While the percentage of occurrence of IG in 2009 averaged about 25 below (p < 0.01) the control (62%), corresponding values for LB were about twice the 8% in the control.…”

“…On the contrary, harvesting NWSGs appropriately stimulates vegetative growth through faster leaf blade expansion and axillary tiller development [40]. These results, like earlier reports on ground cover [34], suggest that harvesting regimes did not compromise subsequent early-season recovery. Therefore, forage harvesting alone may not decrease the proportions of these perennials in similar stands.…”

“…By the end of each growing season, all first-and second-year plots had 1, 2, 3 or 4 additional harvest(s), according to treatment. Occasionally, harvesting was hastened by one to two or delayed for up to six days to avoid major rainfall events, thus allowing optimum machine operation [34]. In spring 2009, the Y307 plots, with two years in production, were harvested only once in May to assess subsequent early-season recovery before being removed from the harvest regime (retired).…”

“…In mixed stands, defoliation often impacts forbs more heavily due to their growing points being mostly above the cutting heights. This often reduces their proportions in recovering stands, as reflected in their reported contribution to ground cover [34]. During 2009 and 2010, the six most frequent forbs were Chamaecrista fasciculata (CHFA), Ipomoea lacunosa (IPLA), Rumex crispus (RUCR), Cassia obtusifolia (CAOB), Helianthus maximiliani (HEMA) and Solidago canadensis (SOCA).…”

Effects of Planting Method on Enhanced Stand Establishment and Subsequent Performance of Forage Native Warm-Season Grasses

“…So, incorporating NWSGs into the pasture systems will most likely improve summer forage production and availability in the region. For over a decade now, the mid-south and southeastern regions of the US have seen a growing interest in NWSGs mainly due to their superior summer forage potential (Angima et al, 2009;Temu et al, 2014a), wildlife habitat quality features (Temu et al, 2014b), and low-input demand. Of the NWSGs, big bluestem (BB, Andropogon gerardii Vitman), eastern gamagrass (GG, Tripsacum dactyloides L.), indiangrass [IG, Sorghastrum nutans (L.).…”