Bird Diversity and Composition in Even-Aged Loblolly Pine Stands Relative to Emergence of 13-year Periodical Cicadas and Vegetation Structure
In southern Arkansas, l&year periodical cicadas (Magicicada spp.) were expected to emerge in late April and early May of 1998. Presence of a superabundant food source, such as periodical cicadas, may attract greater numbers of b i r d s a n d m o r e s p e c i e s o f b i r d s t h a n i s u s u a l l y p r e s e n t i n a p a r t i c u l a r a r e a . T h r e e e v e n a g e d l o b l o l l y p i n e (Pinus faeda L . ) stands were surveyed for birds by using a fixed-width transect before, during, and after emergence of the periodical c i c a d a s . E m e r g i n g c i c a d a n y m p h s w e r e t r a p p e d a n d c o u n t e d t o o b t a i n a n e s t i m a t e o f c i c a d a d e n s i t y . T h e d e n s i t y o f cicadas in these pine stands was considerably lower than densities reported for other forest stands in the Eastern U.S. Bird d i v e r s i t y w a s v a r i a b l e b e t w e e n m o n t h s a n d s t a n d s b u t d i d n o t a p p e a r t o b e s t r o n g l y i n f l u e n c e d b y t h e p r e s e n c e o f p e r i o d i c a l c i c a d a s . B i r d c o m p o s i t i o n i n t h e s e m a n a g e d l o b l o l l y p i n e s t a n d s w a s s i m i l a r t o t h a t i n u n m a n a g e d , e v e n a g e d p i n e a n d p i n e / h a r d w o o d s t a n d s o f s i m i l a r a g e s . INTRODUCTION Emergence of periodical cicadas (Homoptera: Cicadidae: Magicicada) is a highly predictable occurrence. The l3-year race of periodical cicadas that occurs in Arkansas is a group of three species including Magicicada tredecim (Walsh and Riley), M. tfedecassirti (Alexander and Moore), and M. tredecula (Alexander and Moore). Adult cicadas synchronously emerge from the ground every 13 years, ascend the nearest tree, and cast their nymphal skin. Adult males aggregate in the forest canopy and form chorusing centers to attract females for mating (Williams and Smith 1991). Adults complete their reproductive cycle and die within 4 to 6 weeks. Adult populations of periodical cicadas can be very dense. Populations in previous emergences have been estimated at tens of thousands to hundreds of thousands of individuals per acre (Dybas and Davis 1962, Rodenhouse and others 1997, White and others 1962). This type of ephemeral, high density occurrence of insects can provide a superabundance of food that may attract greater numbers and more species of insectivorous birds than is usually present in a particular location. In this study, we investigated the influence of 13-year periodical cicadas on bird diversity in even-aged stands of loblolly pine (Pinus taeda L.) in southern Arkansas where periodical cicadas were observed during a previous emergence (personal observation, M.D. Cain, 1985). The study also provided an opportunity to examine bird composition relative to vegetation structure of loblolly pine stands that were managed to maximize pine development. Others have examined bird composition relative to vegetation structure in unmanaged, even-aged pine and pine/hardwood stands (Childers and others 1986, Conner and others 1979, Conner and others 1983, Dickson and Segelquist 1979, Kellner 1996), but this information is lacking for managed stands. Recent concern over declining populations of neotropical migratory songbirds and an increasing interest in managing forests at the ecosystem level warrants an examination of bird communities inhabiting forests managed for timber production (Finch and Stangel 1993). METHODS Study Sites Three plots were surveyed for birds and cicadas on the Crcssett Experimental Forest, Ashley County, Arkansas. Merchantable-sized trees (a3.5 in. d.b.h.) on all plots were primarily loblolly pine, but a few shortleaf pine (Pinus echinafa Mill.) and assorted hardwood species were present. Plot 5 is a 1 O-acre, 25year-old stand measuring 1,320 ft long and 330 ft wide. This stand was precommercially and commercially thinned and periodically prescribe burned in winter (Cain 1996). Burning was initiated in the ninth year to control understory vegetation. The most recent bum was conducted in February 1998. Plot 5 also had patches of unmanaged pine and openings that supported grasses and forbs. Plots 37N and 37s are both 15-year-old loblolly pine stands. Plot 37N is 1,000 ft long and 165 ft wide (3.8 acres), and plot 37s is 660 ft long and 330 ft wide (5.0 acres). As part of one ongoing study, plots 37N and 37s have been similarly managed (Cain 1997). Both plots were precommercially and commercially thinned and competing vegetation was controlled with herbicides, manual removal, or both during the first 5 years of pine development. These two plots also had patches of unmanaged pine. All plot boundaries were well-defined by mowed fire lanes. Bird Survey Birds were surveyed using a fixed-width transect (Mikol 1980). A transect was established through the center of each plot. Bird surveys were conducted along each transect for 2 days each in early-April, mid-May, and mid-June of 1998. Each 2-day survey was completed within a 4-day period. All birds detected by sight or sound within the plot boundary were recorded and plotted on a map as the observer slowly traversed the transect. In addition, all birds detected within 80 ft outside the plot boundary were recorded and mapped for two reasons. First, birds were not confined to our artificially-defined boundaries. Second, birds in the periphery were observed using the study plots. ’ P a p e r p r e s e n t e d a t t h e T e n t h B i e n n i a l S o u t h e r n S i l v i c u l t u r a l R e s e a r c h C o n f e r e n c e , S h r e v e p o r t , L A , F e b r u a r y 1 6 1 8 , 1 9 9 9 . ’ Biological Science Technician and Research Forester, USDA Forest Service, Southern Research Station, P.O. Box 3516, Monticello, AR 71656,
Associations of avian and herpetofauna communities with forest management at multiple spatial scales
.................................................................................................xv CHAPTER
DEM generation from new VIR sensors: IKONOS, ASTER and Landsat-7
DEM generation is a living R&D topic since new-launched satellite images can be used to generate stereoscopic images. Using a coplanarity equation model developed at CCRS and an automatic matching method developed at PCI, DEMs are generated with new VIR stereo data. Accuracy of 4.9 m with high-resolution IKONOS images, and 33 m and 101 m with medium-resolution ASTER and Landsat-7 ETM/sup +/ images respectively are obtained. The same matching accuracy of one-pixel is translated into worse results with Landsat due to a small B/H ratio of 0.15.