Influence of atmospheric CO2 enrichment, soil N, and water stress on needle surface wax formation in Pinus palustris (Pinaceae)

Interactive effects of increasing atmospheric CO2 with resource limitations on production of surface wax in plants have not been studied. Pinus palustris seedlings were grown for 1 yr at two levels of soil N (40 or 400 kg N_ha-1_yr-1) and water stress (-0.5 or -1.5 MPa xylem pressure potential) in open-top field chambers under two levels of CO2 (365 or 720 mumol/mol). Needle surface wax content was determined at 8 mo (fall) and 12 mo (spring) and epicuticular wax morphology was examined using scanning electron microscopy (SEM) at 12 mo. Wax content expressed on both a leaf area and dry mass basis was increased due to main effects of low N and water stress. No main effects of CO2 were observed; however, a CO2 x N interaction at 12 mo indicated that under low soil N the elevated CO2 treatment had less wax (surface area or dry mass basis) compared to its ambient counterpart. Morphologically, low N needle surfaces appeared rougher compared to those of high N needles due to more extensive wax ridges. Although the main effect of water treatment on wax density was not reflected by changes in wax morphology, the CO2 x N interaction was paralleled by alterations in wax appearance. Decreases in density and less prominent epicuticular wax ridges resulting from growth under elevated CO2 and limiting N suggest that dynamics of plant/atmosphere and plant/pathogen interactions may be altered.     

Elevated atmospheric CO2 differentially affects needle chloroplast ultrastructure and phloem anatomy in Pinus palustris: interactions with soil resource availability

The response of forest species to increasing atmospheric CO₂, particularly under resource limitations, will require study in order to predict probable changes which may occur at the plant, community and ecosystem levels. Longleaf pine (Pinus palustris Mill.) seedlings were grown for 20 months at two levels of CO₂ (365 and 720 μol mol¹) in two levels of soil nitrogen (4 and 40 g m^?2), and with two levels of soil moisture (–0·5 and –1·5 MPa xylem pressure potential). Leaf tissue was collected in the spring (12 months exposure) and autumn (20 months exposure) and examined using transmission electron microscopy (TEM) and light microscopy. During early spring, elevated CO₂ magnified effects of N and water treatment on starch accumulation and in some cases contributed to altered organization of mesophyll chloroplasts. Disruption of chloroplast integrity was pronounced under elevated CO₂, low N and water stress. In autumn, needles contained little starch; however, chloroplasts grown under high CO₂ exhibited stress symptoms including increased plastoglobuli and shorter grana. A trend for reduced needle phloem cross-sectional area resulting from fewer sieve cells was also observed under elevated CO₂. These results suggest that, in nature, longleaf pine seedlings may not benefit from a doubling of CO₂, especially when soil resources are limiting.     

Isolation and characterization of polymorphic microsatellite loci in the raccoon (Procyon lotor)

We report the isolation and characterization of 17 polymorphic microsatellite loci in the North American raccoon (Procyon lotor). These loci exhibit high levels of allelic diversity, with between four and 13 alleles per locus, and heterozygosity, with observed values of 0.500-1.000 in a sample of 20 individuals. All genotypes conformed to Hardy-Weinberg expectations and there were no instances of linkage disequilibrium detected.     

Effects of Chronic Human Activities on Invasion of Longleaf Pine Forests by Sand Pine

Chronic human activities may result in new and permanent successional trajectories in certain ecosystems. The invasion of longleaf pine ecosystems by sand pine in the Florida Panhandle is one such change in the landscape. This study examined the spatial pattern of sand pine expansion and explored the natural and anthropogenic disturbances that fostered this invasion. Aerial photographs (1949, 1994) and Geographic Information Systems analyses confirmed sand pine expansion at Eglin Air Force Base. In 1949, there were 8,982 ha of sand pine in the southern portion of the study area near riparian and coastal lowland forests. By 1994, sand pine had expanded further upland and inland, for a total of 17,147 ha in the study area. Sand pine age data showed that this expansion had started by 1920 but increased rapidly in the 1940s. Historical accounts and structural data from stands suggest that land-use activities associated with the extraction of turpentine promoted the invasion by sand pine. Fires were suppressed in longleaf pine forests to protect turpentine trees, resulting in increased vegetation cover and decreased regeneration of longleaf pine. In addition, stands were typically harvested after turpentining, and there was little or no advanced regeneration of longleaf pine. Sand pine age histograms showed that the onset of high establishment rates (1940s) coincided with changes in land ownership and widespread fire suppression. Sand pine is likely to persist in these ecosystems due to its abundant regeneration. Received 17 March 1999; accepted 28 January 2000.     

Are raccoons limited by the availability of breeding resources? Evidence of variability in fecundity at fine spatial scales

Despite their behavioral plasticity, recent research suggests raccoons (Procyon lotor) exhibit variability in demography and genetic structure among individual habitat patches in landscapes heavily affected by anthropogenic land use. Consequently, elucidation of vital rates at fine-spatial scales is needed to implement appropriate management strategies for this species. To evaluate the degree of variability in productivity that exists among individual habitat patches, we collected reproductive (n = 170) and cementum annuli age data (n = 383) for raccoons occupying 30 forest patches varying in local and landscape-level habitat attributes within a highly fragmented agricultural ecosystem. Across all females sampled, pregnancy rates averaged 85% but were highly variable among ages (range: 47–100%). Average litter sizes ranged from 3.2 to 4.7, but did not differ as a function of age. At the landscape-level, we observed significant variability among habitat patches in the total number of offspring produced (range: 0–80), indicating that individual patches vary in their contribution to the overall size and stability of the global (landscape-level) population. Variability in productivity among habitat patches primarily was driven by local differences in the availability of denning resources, likely because of the influence of this variable on variability in the number, age structure, and reproductive rate of females. Our results suggest that in agricultural ecosystems, the reproductive potential and temporal stability of raccoons within individual habitat fragments is inextricably linked to the density of tree cavities. © 2012 The Wildlife Society.     

Restoration of Northwest Florida Sandhills Through Harvest of Invasive Pinus clausa

Across much of the southeastern U.S.A., sandhills have become dominated by hardwoods or invasive pine species following logging of Pinus palustris (longleaf pine) and fire suppression. At Eglin Air Force Base where this study was conducted, Pinus clausa (sand pine) has densely colonized most southeastern sandhill sites, suppressing groundcover vegetation. The objectives of this study were: to determine if suppressed groundcover vegetation recovers following the removal of P. clausa; to compare species composition and abundance in removal plots with that in reference, high quality sandhills; to test the assumption that recolonization by P. clausa seedlings decreases with proximity to the centers of removal plots; and to measure the survival of containerized P. palustris seedlings that were planted on P. clausa removal plots. One year post‐removal (1995), the number of plant species decreased by 50%, but then increased by 100% from 1995 to 1997, followed by a small reduction in 1998. The number of plant species was greater in reference plots than in removal plots prior to 1997. Eighty‐five percent of the original species were recorded 4 years post‐harvest in removal plots. Shrubs and large trees remained at low density after harvest. Densities of graminoids, legumes, other forbs, woody vines, and small trees increased after harvest. Plant densities of all life forms, except woody vines, were greater in reference plots than in removal plots. The density of recolonizing P. clausa seedlings 2–4 years post‐harvest significantly decreased with increasing proximity to the centers of removal plots. On average, 80% of planted P. palustris seedlings survived their first 2 years. Harvest of P. clausa followed by fire and the planting of P. palustris is a reasonably effective restoration approach in invaded sandhills. However, supplementary plantings of some herbaceous species may be necessary for full restoration.     

Development of 14 multiplexed microsatellite loci for raccoons Procyon lotor

In order to complement ecological information with genetic data we isolated and characterized 14 polymorphic microsatellite markers from raccoons (Procyon lotor). Three multiplexed panels comprising the loci were developed and 29 individuals from a contiguous habitat patch in northern Indiana, USA were genotyped. The number of alleles per locus ranged from four to 18, and overall heterozygosities ranged from 0.31 to 1.00. One locus was identified as possibly being X‐linked, since males appeared to be hemizygous. Data generated using these markers will be used to further our understanding of small‐scale raccoon population dynamics in a highly fragmented landscape.