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

Vitalis Temu,Loren Burger,Samuel Riffell,K Reddy,Brian Baldwin

doi:10.3390/environments1010075

Vitalis Temu, Loren Burger + Show 3 more

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https://doi.org/10.3390/environments1010075

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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 multi-purpose 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 more sunlight. Similarly, harvest duration increased grass cover with no year effect but reduced forbs following a high rainfall year. One- or two-year full-season harvesting of similar stands may not compromise subsequent bobwhite nesting-cover provided post-season harvesting starts after the breeding cycle is completed.

Highlights

Agricultural intensification contributed to bird population declines on farmlands in Europe and America [1]
Effects of the previous-year harvest regimes (Figure 2) on current-year nesting-cover attributes for bobwhite were assessed
The fact that differences in post-season cover by vegetation or plant litter, among harvested plots, were not observed in one year and were only between the 30- and 120-d in the other year indicated that careful haying in one year may not compromise early summer wildlife habitat quality features associated with sward structure in the following year

Summary

Introduction

Agricultural intensification contributed to bird population declines on farmlands in Europe and America [1] This mainly resulted from the influence of anthropogenic disturbances on interactions between ecosystem components in the plant communities. Practices such as clearing and burning to prepare seedbeds or remove standing dead mass usually produce dense swards with simple structure and less species diversity, which decrease availability or access to food and leave farm-land birds more exposed to predators and weather [1]. Though infrequent application of these practices may not drastically impact habitat quality for wildlife, the reverse is true for extensive and mechanized farm operations These operations may lead to total loss of wildlife habitat or fragmentation and isolation of their remnant patches impacting availability of food and cover [1,3]. This increases predation risks and mortality of young birds unable to escape machinery operations

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