Responses of wetland invertebrates and plants important in waterfowl diets to burning and mowing of emergent vegetation

Abstract

We examined the responses of invertebrates and plants important in waterfowl diets to two management methods (prescribed burning and mowing) commonly used in seasonal wetlands. Experimental plots were constructed in summer 1992 in stands of saltgrass (Distichlis spicata); 50% of the vegetation was removed in treatment areas (10 m x 10 m) by either burning or mowing. After the plots were flooded, we sampled aquatic invertebrates monthly from we sampled plants that grew in areas that had been burned or mowed. Burning and mowing treatments had very different results. Many numerically dominant macroinvertebrates and microinvertebrates had higher densities in burned treatment areas than in unmanipulated control areas, but densities of most taxa were not different in mowed treatment areas and control areas. Copepod densities were lower in burned treatment areas and oligochaete densities were lower in mowed treatment areas than in control areas. Midge (Diptera: Chironornidae) biomass was higher in burned and mowed treatment areas than in control areas. Plant species richness and percent cover of some plant taxa were higher in burned areas than in control areas. Many of the invertebrates and plants we sampled are important in waterfowl diets, and our results indicate that these methods can enhance waterfowl food resources.

Effect of Typha domingensis cutting: response of benthic macroinvertebrates and macrophyte regeneration

“…Besides, considering some characteristics of T. domingensis stand, such as a palustrine area with low water column oscillation (only a few centimeters), and also considering the sampling method, a low diversity of macroinvertebrates was noticed in the study area. Thus, our assumptions seem to be in agreement with those found by Kostecke et al (2005) and Szalay & Resh (1997).…”

“…Two factors were considered: sampling date and treatment. Only taxa with abundance > 4% were considered, we used this criteria of matrix reduction because rare species do not present analyzable patterns (Field et al 1982, Szalay & Resh 1997. The macroinvertebrate densities were log transformed log (x + 1) to reduce data variations.…”

“…Kostecke et al (2005) also detected little difference in the response of aquatic invertebrates to mechanical management in Typha spp. However, Szalay & Resh (1997) observed that areas colonized by Distichlis spicata (Poaceae) subjected to fire and cut disturbances tend to show elevated abundances of Chironomidae, Hemiptera and Oligochaeta. Also, Szalay & Resh (1997), verified that the abundance of the latter (Oligochaeta) maybe be decreased as a response to the cut disturbance.…”

“…However, Szalay & Resh (1997) observed that areas colonized by Distichlis spicata (Poaceae) subjected to fire and cut disturbances tend to show elevated abundances of Chironomidae, Hemiptera and Oligochaeta. Also, Szalay & Resh (1997), verified that the abundance of the latter (Oligochaeta) maybe be decreased as a response to the cut disturbance. Our results are in according with Szalay & Resh (1997), suggesting that Tubificidae responded negatively to the cut disturbance in the treatment.…”

“…Several works have aimed to evaluate the benthic macroinvertebrate responses to different kinds of disturbances in wetlands. These studies suggest a broad variation of responses (Szalay & Resh 1997, Szalay & Cassidy 2001, Martin & Neely 2001, Kostecke et al 2005, Schmidt et al 2005, Rehage & Trexler 2006, Silveira et al 2011b. Benthic macroinvertebrates are a useful tool for environmental agencies (Rodrigues et al 2006), providing consistent information related to multiple sources of disturbance and response (Rosenberg & Resh 1992).…”