@article{simons_shriner_farnsworth_2006, title={Comparison of breeding bird and vegetation communities in primary and secondary forests of Great Smoky Mountains National Park}, volume={129}, ISSN={["1873-2917"]}, DOI={10.1016/j.biocon.2005.10.044}, abstractNote={We compared breeding bird communities and vegetation characteristics at paired point locations in primary (undisturbed) and mature secondary forest (70–100 years old) sites in Great Smoky Mountains National Park, USA to understand how sites logged prior to creation of the park compare to undisturbed sites following 70 years of protection from human disturbance. We found that bird and vegetation communities are currently similar, but retain some differences in species composition. Rank abundance curves for primary and secondary forest bird communities showed very similar patterns of species dominance. Species composition was also similar on the two sites which shared 24 of the 25 most frequently recorded species. Nonetheless, comparisons of density estimates derived from distance sampling showed three bird species were more abundant on primary forest sites and that one bird species was significantly more abundant on secondary forest sites. Notably, comparisons based on raw counts (unadjusted for potential differences in detectability) produced somewhat different results. Analyses of vegetation samples for the paired sites also showed relative similarity, but with some differences between primary and secondary forests. Primary forest sites had more large trees (trees greater than 50 cm diameter at breast height) and late successional species. Primary forest sites had a denser tall shrub layer while secondary forest sites had a denser canopy layer. Nonetheless, tree species richness, basal area of live trees and number of standing snags did not differ between primary and secondary forest sites. Results indicate that breeding bird communities on sites within the park that were logged commercially 70 years ago are currently quite similar to bird communities on sites with no history of human disturbance. Similarities between the bird communities on previously disturbed and undisturbed sites in Great Smoky Mountains National Park may exceed those on more fragmented landscapes because large patches of primary forest, adjacent to commercially logged sites, remained in the park when it was established in 1935. These patches of primary forest may have served as source areas for commercially logged sites.}, number={3}, journal={BIOLOGICAL CONSERVATION}, author={Simons, TR and Shriner, SA and Farnsworth, GL}, year={2006}, month={May}, pages={302–311} }
 @article{lichstein_simons_shriner_franzreb_2002, title={Spatial autocorrelation and autoregressive models in ecology}, volume={72}, ISSN={["1557-7015"]}, DOI={10.2307/3100099}, abstractNote={Recognition and analysis of spatial autocorrelation has defined a new paradigm in ecology. Attention to spatial pattern can lead to insights that would have been otherwise overlooked, while ignoring space may lead to false conclusions about ecological relationships. We used Gaussian spatial autoregressive models, fit with widely available software, to examine breeding habitat relationships for three common Neotropical migrant songbirds in the southern Appalachian Mountains of North Carolina and Tennessee, USA. In preliminary models that ignored space, the abundance of all three species was correlated with both local- and landscape-scale habitat variables. These models were then modified to account for broadscale spatial trend (via trend surface analysis) and fine-scale autocorrelation (via an autoregressive spatial covariance matrix). Residuals from ordinary least squares regression models were autocorrelated, indicating that the assumption of independent errors was violated. In contrast, residuals from autoregressive models showed little spatial pattern, suggesting that these models were appropriate. The magnitude of habitat effects tended to decrease, and the relative importance of different habitat variables shifted when we incorporated broadscale and then fine-scale space into the analysis. The degree to which habitat effects changed when space was added to the models was roughly correlated with the amount of spatial structure in the habitat variables. Spatial pattern in the residuals from ordinary least squares models may result from failure to include or adequately measure autocorrelated habitat variables. In addition, contagious processes, such as conspecific attraction, may generate spatial patterns in species abundance that cannot be explained by habitat models. For our study species, spatial patterns in the ordinary least squares residuals suggest that a scale of 500–1000 m would be appropriate for investigating possible contagious processes.}, number={3}, journal={ECOLOGICAL MONOGRAPHS}, author={Lichstein, JW and Simons, TR and Shriner, SA and Franzreb, KE}, year={2002}, month={Aug}, pages={445–463} }
 @article{simons_farnsworth_shriner_2000, title={Evaluating Great Smoky Mountains National Park as a population source for the Wood Thrush}, volume={14}, ISSN={["0888-8892"]}, DOI={10.1046/j.1523-1739.2000.98606.x}, abstractNote={Abstract: The prevailing fragmentation paradigm predicts that large, intact forests are acting as population sources for Neotropical migrant landbirds. We used the Wood Thrush (  Hylocichla mustelina) as a model for evaluating the role Great Smoky Mountains National Park (the largest national park in the eastern United States) may play in maintaining regional songbird populations. We estimated the annual productivity of Wood Thrushes in the park by combining observations on the birds' distribution, abundance, and productivity with estimates of habitat availability. We estimated a breeding population of approximately 10,000 nesting pairs using habitat models developed from over 2500 point‐count censuses conducted across the park. Data from 426 nests monitored from 1992 to 1997 produced a daily nest survival rate of 0.96. We estimated an annual fecundity of 2.76 fledglings per breeding pair, based on a model that incorporated the re‐nesting behavior of Wood Thrushes. Results indicate that the park is producing approximately 3000 surplus female young each year. Daily nest survival rates were below those reported in other studies of Wood Thrushes in large forest tracts. The relatively high productivity of 3.31 nestlings per successful nest suggests that, in the absence of predation, the park provides high‐quality nesting habitat for Wood Thrushes, but that it may also support a more diverse and abundant predator community than more disturbed or less contiguous sites. The difficulties of estimating the size of continental breeding bird populations make assessing the significance of the park within a regional landscape context problematic, but our estimates suggest that, although the park is functioning as a substantial population source on a local scale, its potential to sustain regional or continental Wood Thrush populations is limited. Our findings suggest that species such as the Wood Thrush are capable of moderate levels of surplus productivity in high‐quality habitat, but that extensive areas of suitable habitat outside protected areas and other public lands will be required to sustain continental breeding populations.}, number={4}, journal={CONSERVATION BIOLOGY}, author={Simons, TR and Farnsworth, GL and Shriner, SA}, year={2000}, month={Aug}, pages={1133–1144} }