Albert J. Meier

Possible Ecological Mechanisms for Loss of Vernal-Herb Diversity in Logged Eastern Deciduous Forests

The ecological literature on eastern forest-floor herbs and data collected in the southern Appalachians in Tennessee and North Carolina suggest five possible ecological mechanisms for reducing or limiting alpha diversity of vernal herbs in logged stands, three of which may also account for the slow recovery of some herbaceous species: (1) logging reduces populations of rarer herbs; (2) populations of forest-floor species are further reduced during the successional stages following logging, either by inability to adapt to changed microclimate or by competition with r-selected species that are better dispersers and better able to tolerate desiccation and increased radiation; (3) forest-floor herbs have slow growth and reproduction rates, thus population densities increase slowly; (4) many forest-floor herbs are clonal, ant-dispersed, or gravity-dispersed, thus they are slow to reoccupy suitable habitat once extirpated or greatly reduced in population numbers; and (5) logging results in less-than-optimal conditions for forest-floor herb reproduction by modifying microhab- itats on the forest floor and by temporarily eliminating gap-phase succession. The data indicate some species of vernal herbs are far more tolerant of disturbance than others, and that sensitive species can be identified and utilized as indicators of community integrity and diversity.

Longitudinal patterns of fish assemblages in small unregulated subbasins: evaluating reach- and watershed-scale parameters

Fish assemblage relationships with environmental parameters were studied in four small unregulated subbasins in the speciose Upper Green River Basin of central Kentucky, USA. One subbasin drains into a tributary of the Green River and produced the lowest species (28) richness. The three other subbasins drain directly into the Green River and supported 41−59 species. Parameters were partitioned into watershed- and reach-scale spatial categories. Watershed area per stream segment and stream-size related environmental parameters at the reach scale produced the highest loadings of a principle components analysis (PCA), and both PCA Axes 1 and 2 for all subbasins were reflective either of watershed area or stream-size parameters. Small loadings were produced by all watershed-scale land-use parameters and all reach-scale water chemistry parameters. Fish richness and diversity were positively correlated with watershed area for the two largest subbasins and for the three Upper Green River subbasins combined. The lack of a linear relationship, however, between the residuals of multiple linear regression models between richness and diversity versus stream width, percent bedrock, percent pool and percent fine substrates indicated that a simple species area relationship was not operating. A detrended correspondence analysis (DCA) performed for each subbasin showed that several fish species were associated mainly either with small, upland segments or conversely the largest, deeper segments, and each subbasin yielded significant correlations between the environmental PCA loadings and fish assemblage DCA site scores. These results indicated that within the regional scale, and in absence of steep disturbance gradients, stream fish assemblages can reflect natural hydrologic and geomorphic gradients.

Restoring Wildflowers and Salamanders in Southeastern Deciduous Forests

need help. In the eastern deciduous formanyways est is resilient to disturbance. A majority of the dominant woody angiosperms sprout readily from stumps or roots and regenerate quickly after windfall, fire or logging. Since rainfall is relatively reliable and adequate to support dense covers of herbs and grasses, secondary succession usually begins immediately after forest clearing. Where agricultural fields have been abandoned, the forest soon returns. Pines or red cedars may occupy an open area within a few years, and other taxa, such as maples, oaks and hickories soon follow. Due to the speedy recovery of forest canopies, conservationists have, perhaps incorrectly, assumed that active restoration of eastern deciduous forest is usually unnecessary, except on sites where an activity such as coal mining has displaced the overburden or erosion has removed most of the soil. Common wisdom holds that, in contrast with other ecosystems such as prairies, which generally do not recover following severe disturbance, most woodlots will recover on their own, as will more extensively logged stands. Twenty meters of canopy regrowth in 40 to 80 years seems to demonstrate ecosystem integrity. It also reestablishes the shady, moist microclimate needed by understory herbs and shrubs, salamanders and other plants and animals characteristic of forests. And this being the case, there has been a tendency to assume that these, often less conspicuous, species will return to disturbed sites on their own once canopy development, litter accumulation and other forest features have reached a certain stage. A series of recent studies of the loss and recovery of biodiversity in the forests of the southern Appalachians following disturbances, such as logging and agriculture, has revealed, however, that many species are very slow to return to intensively disturbed or very fragmented sites. In some cases, mesic forest stands in the southern Appalachians that had been clearcut 90 years earlier have not yet recovered the full diversity of their vernal herbaceous flora (Duffy and Meier, 1992). It might take an indeterminate length of time for the number of vernal herbs per square meter to return to pre-logging levels. And there is evidence this may be true for certain animal species as well. J.W. Petranka and his colleagues at the University of North Carolina, Asheville, found that the species diversity of salamanders was reduced as a result of clear cutting in lowerelevation mixed-mesophytic and oak forests, and estimated that recovery of the herpetofauna may take at least seventy years (Petranka et al., 1993). Indeed, our own work strongly suggests that woodlots along the Blue Ridge Parkway, isolated from surrounding forests by as little as 50 meters of farm fields, may be virtually inaccessible to salamanders. In another study, a team of college students found that stream valleys with young or very fragmented forest occurring primarily as isolated woodlots were missing herbaceous species that were present in mature or con-

Algal biomass accrual in relation to nutrient availability and limitation along a longitudinal gradient of a karst riverine system

Nutrient availability influences growth, productivity, and community structure of primary producers. Nutrient limitation, however, results from a deficiency mainly in nitrogen (N) or phosphorus (P) levels relative to cellular growth needs. Limitation is a function of biotic and abiotic factors, the latter including land-use activities (e.g., agriculture, septic systems) and underlying bedrock features. The purpose of this study was twofold: (1) to assess the relationship between algal biomass and ambient nutrient levels along the longitudinal course of a river through a transition from weak to well-developed underlying karst bedrock and (2) experimentally assess if periphyton was N- or P-limited between weak and well-developed karst reaches. Sestonic and Cladophora biomass (=chlorophyll-a) levels increased sharply along the longitudinal gradient. Cladophora biomass, in particular, was strongly correlated with nitrate levels. In contrast, periphyton biomass (=chlorophyll-a) levels were sporadic and did not display a longitudinal pattern. With the exception of ammonia, individual nutrient levels generally increased longitudinally and were higher in the downstream karst reaches. Total N/total P ratios also increased longitudinally and were >25 throughout the study region, suggesting P limitation. The results of the nutrient limitation studies, however, coupled with high concentrations of both N and P throughout the study reach in excess of eutrophication thresholds, suggest that total nutrients are not limiting within the study region. Overall, Kentuckys upper Green River appears to be a nutrient-enriched, eutrophic system and particularly in the downstream, well-developed karst reaches.

GIS and Artificial Neural Network-Based Water Quality Model for a Stream Network in the Upper Green River Basin, Kentucky, USA

AbstractThe prediction of stream water quality (WQ) is essential to understand and quantitatively describe water quality parameters (which include physical characteristics, inorganic metallic, and nonmetallic concentrations) and their structure, watershed health, biodiversity, and ecology of a basin. The spatial variability and temporal randomness of stream water quality parameters makes the problem a complex modeling task by ordinary statistical regression methods. The determination of water quality parameters and their spatial and temporal description in stream networks is even more complex due to the stochastic nature of water flow, atmospheric conditions, meteorological patterns, and nonlocal effects of precipitation and temperature. In this paper, a statistical, geographic information system (GIS) and a neural network based water quality model is developed to study stream water quality parameter structure in a geographic framework in the United States of America (USA) consisting of stream network, wa...

The Effects of Fire and Other Habitat Characteristics on Habitat Selection of Exyra ridingsii (Riley), the Riding's Pitcherplant Looper Moth

ABSTRACT  Exyra ridingsii is a host-specific moth that spends its entire immature life cycle in the Sarracenia flava L. pitcher plant. Sarracenia flava requires a habitat that undergoes frequent fires and has acidic moist soil. During this investigation we studied the degree to which E. ridingsii damaged S. flava under different environmental conditions. From summer 2012 to fall 2013, five sites in the Croatan National Forest, North Carolina, were surveyed four times each year. At each site, 7 to 20 quadrats were randomly selected for sampling. In each quadrat, pitchers were counted and measured for height and whether the pitchers were affected by herbivory; the fraction affected was calculated (herbivory per clump). Median herbivory per clump at the burned sites ranged from 86–100%. All other sites ranged from 50–75% with the exception of the unburned pocosin site, which was the lowest at 32%. Herbivory per clump was found to differ by site, but because sites varied in environmental characteristics other than burn status, other factors playing a role in habitat status cannot be ruled out. Tallest median trumpet heights were found at the unburned sites. During this study, E. ridingsii repopulated S. flava pitchers in the burned sites less than two months after fire, suggesting that they persist as a metapopulation.

The Case of the 30-Year Persistence of the Single Known Population of Panax quinquefolius L. (Araliaceae) in Louisiana

Abstract There were a total of 12 documented Panax quinquefolius (American Ginseng) in the only known population in Louisiana in 1986. Our reassessment of the population in 2016 found 16 plants. We suggest that the long-term persistence of this tiny American Ginseng population indicates that simple matrix-population models may be overestimating quasi-extinction numbers and minimum viable populations, perhaps as a result of failing to sufficiently consider influences of environmental conditions. We further suggest that this, the southernmost documented population of the species in the US, has endured beyond expectation but remains at acute risk of extirpation and that any population-specific genes are at risk of loss if no intervention is made to protect the population.

Effects of Exyra ridingsii (Lepidoptera: Noctuidae) on Sarracenia flava (Nepenthales: Sarraceniaceae)

Abstract Exyra ridingsii (Riley) (Lepidoptera: Noctuidae) is a moth whose obligate host is the pitcher plant Sarracenia flava (L.) (Nepenthales: Sarraceniaceae). The entire life cycle of the moth is completed in the trumpets of this fire-dependent plant that is found throughout the southeastern United States in bogs, long-leaf pine savannas, and pocosins. The purpose of this study was to determine the effects of E. ridingsii on S. flava, including the effect of herbivory on trumpet height in the year subsequent to feeding and whether moths select trumpets for oviposition based on height. Although most forms of herbivory by insects might be expected to have negative effects on plants by reducing photosynthetic abilities, it would be counterproductive for herbivory by E. ridingsii to negatively affect S. flava as this plant is the only possible habitat for E. ridingsii. At each site in selected quadrats, the number of trumpets, trumpet height, trumpet status, number of trumpets in a clump, and number of clumps were recorded. The relationship between height and herbivory was analyzed using a linear model, and a positive correlation was found between height and herbivory. E. ridingsii herbivory had no effect on the next years growth of S. flava based on a Spearmans correlation. Therefore, we concluded that E. ridingsii has little effect on S. flava populations and has likely evolved to selectively avoid herbivory on more vulnerable, smaller plants.

Pitcher Plant Moths (Exyra) Fly from Pitchers in Response to Smoke

ABSTRACT. Pine savannas in the Southeastern United States are subject to an historical regime of periodic fire, with many and varied ecological consequences. Insectivorous plants of the genus Sarracenia (L.) (Sarraceniaceae) often entirely lose their aboveground leaves to these periodic fires. During the growing season, these tubular leaves, which act as pitfall traps for insects, are host to pitcher plant moths, Exyra (Grote) (Noctuidae), which live their entire life cycle within the plant. This study tested the effect of smoke on a small sample of Exyra semicrocea in pitchers, and demonstrated that they respond quickly by flight.

Notes on the ecological roles of Podostemum ceratophyllum Michx., 1803 and Cladophora glomerata (L.) Kütz., 1843 in the habitat and diet of riverine hydropsychid caddisflies (Trichoptera)

ABSTRACT Larvae of net-spinning Hydropsychidae caddisflies (Trichoptera) are common inhabitants of lotic systems and are typically categorised as filtering-collectors, but feeding habits vary in response to the availability of food resources. This study addressed two questions. First, are Hydropsyche simulans Ross, 1938 and Cheumatopsyche Wallengren, 1891 found in higher densities in patches of the macrophyte Podostemum ceratophyllum Michx., 1803? Second, do H. simulans and Cheumatopsyche spp. assimilate the filamentous alga Cladophora glomerata (L.) Kütz., 1843 during a late summer bloom? Cladophora glomerata standing stocks increased during summer, coincident with increasing water temperatures and decreasing flow. Densities of both hydropsychid taxa were significantly greater in high (> 75% cover) P. ceratophyllum habitat. A multisource mixing model (IsoSource) using carbon and nitrogen stable isotope data showed that C. glomerata was the prominent assimilated dietary item during August and September. Overall, hydropsychid caddisfly larvae showed a clear habitat association with P. ceratophyllum and the capacity to assimilate C. glomerata when this resource is abundant during summer base-flow conditions.