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summary Plants of Abutilo theophrasti Medic, were grown for two consecutive years in the field. First generation (maternal) plants were grown either with or without mycorrhizal inoculation with Glomus intraradices Schenck & Smith. We collected early and late cohorts of seeds which were used to product second generation (offspring) plants. Offspring plants were grown either with or without mycorrhizal inoculation with G. intraradices. Irrespective of maternal mycorrhizal status, we found that offspring of early cohort seeds had greater percent mycorrhizal colonization early in the growing season, a greater proportion of plants flowering early in the season, and a greater number of capsules per plant at the end of the season compared with offspring of late cohort seeds. These differences were observed despite the fact that shoot N and P concentrations were greater in offspring of late cohort seeds. We found that mycorrhizal colonization of maternal plants decreased the average time to reproductive maturity in offspring plants, but did not significantly influence any other vegetative or reproductive trait in the offspring plants. Mycorrhizal colonization of offspring plants resulted in a greater number of branches per plant and a greater number of mature capsules per branch. Mycorrhizal colonization of offspring plants also resulted in a significant increase in seed P content, bur only for seeds that were produced late in the growing season, We conclude that mycorrhizal colonization of the offspring generation was more important than mycorrhizal colonization of the maternal generation m determining offspring reproductive output, but maternal seed cohort is an important interacting factor that influences offspring fecundity.

T wo recent issues of the Journal of Forestry contained a discussion of methods for estimating private forest landowner (PFL) population parameters. Initially, Metcalf et al. (2012) raised questions about the application of unequal probability estimation equations to samples of PFLs drawn proportional to property size (i.e., PPS). In response, Dickinson and Butler (2013) presented corrections to National Woodland Owner Survey (NWOS) methods that clarified sampling protocols and revised equations and procedures used to generate estimates of PFL parameters. Dickinson and Butler (2013) also raised questions about the validity of the analysis and conclusions reached by Metcalf et al. (2012). This response addresses those questions, amends conclusions presented in Metcalf et al. (2012), and expands the discussion of implications for managers and researchers concerned with private forest ownership and management. It was never our intent to critique and/or debate methodological issues. Our research was funded by the Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry with the specific goal of informing outreach and extension efforts promoting stewardship of the Commonwealth’s vast private forest (approximately 11.5 million acres, 70% of the state’s forestland). This project did not focus on the exploration of the functionality of estimation equations. Our methodological approach was fashioned after the NWOS methods presented in US Department of Agriculture (USDA) Forest Service publications (e.g., Birch 1996, Butler et al. 2005), but coupled to a substantial increase in sampling intensity. After collecting data and conducting different analyses, we were left with curiously incongruent results (e.g., estimates of PFL population size in the millions rather than the hundreds of thousands reported in the NWOS). This finding led us to initiate a systematic review of both the NWOS methods and our own to explore possible sources for bias and/or error. The review uncovered problems with the NWOS estimation equations and their application. We presented these findings in Metcalf et al. (2012), in which we specifically addressed the confusion of inclusion probabilities with selection probabilities and the erroneous exclusion of duplicate PFL selections when using the Hansen-Horvitz estimator (HHE). The implications of these errors on our data and the resources needed to conduct the review itself severely constrained our research. The conclusions tied to estimation approaches helped clarify our research, led to changes in NWOS estimation procedures as presented by Dickinson and Butler (2013), and allowed other researchers to have significantly more confidence when designing and interpreting results from PFL studies. Dickinson and Butler (2013) dismissed the issues presented in Metcalf et al. (2012) as trivial because of an unestablished theoretical basis (p. 319), case study methodology (p. 320), limited sampling intensity of NWOS (p. 323), and unaddressed issues (i.e., nonprivate forest sampling points and variance estimation, p. 323, 324). We disagree. Consumers of NWOS results need to be assured that they are unbiased; researchers using USDA Forest Service methods also need to be assured that their resulting estimates are unbiased. This was not the case before the publication of Metcalf et al. (2102). Indeed, Dickinson and Butler (2013) acknowledged the following two errors in past NWOS methods: confusion of selection probability and inclusion probability calculations; and unwarranted omission of duplicate selections of PFLs in the sampling process. Such errors, when applied to sampling designs identical to NWOS, produce biased estimates (increasingly so as sample size increases), thus potentially affecting past NWOS panels and any PFL study replicating NWOS methods before this discussion. Further, because the source of bias is largely affected by the exclusion of duplicate selections of PFLs, estimates for areas of interest (e.g., regions and states) characterized by larger private forest parcels (i.e., the western United States) may be disproportionately biased. Dickinson and Butler (2013) suggested a review of past NWOS data to explore possible changes in results due to updated methods; we strongly encourage this analysis of legacy NWOS data because it will help us understand the full implication of these errors on past results and reveal true trends in private forest ownership characteristics. Allocations of federal formula funds are, in part, determined by estimates of PFL population sizes by state and/or region. Parcelization patterns vary disproportionately across states: some states are highly parcelized, whereas others are less so. Thus, the likelihood for duplicate selections of PFLs in past NWOS sampling varies from state to state. It follows that the bias in estimates of PFL population parameters (including total population size) may be more pronounced in some states than others; this bias results in skewed resource allocations. Understanding the nature of such errors would not be possible without analysis of past NWOS data using revised methods. This type of legacy analysis to remove past bias is essential for a longitu

Private forest landowners (PFLs) own the majority of eastern US forests, which provide a range of benefits including clean air, watershed protection, wildlife habitat, timber production, and recreational opportunities. Research on this population has been conducted for many years but little has been done to standardize sampling methods or procedures for estimating population parameters, thus frustrating comparisons among studies and longitudinal explorations. This article explores the sampling and estimation methods used by the USDA Forest Service to produce estimates of PFL population parameters. The Forest Service estimation equation is reviewed, its functionality is established given broad application, and modifications are suggested to achieve unbiased estimation and provide methodological standardization for future PFL research.

Integrated weed management tactics are necessary to develop cropping systems that enhance soil quality using conservation tillage and reduced herbicide or organic weed management. In this study, we varied planting and termination date of two cereal rye cultivars (‘Aroostook’ and ‘Wheeler’) and a rye/hairy vetch mixture to evaluate cover-crop biomass production and subsequent weed suppression in no-till planted soybean. Cover crops were killed with a burn-down herbicide and roller-crimper and the weed-suppressive effects of the remaining mulch were studied. Cover-crop biomass increased approximately 2,000 kg ha−1from latest to earliest fall planting dates (August 25–October 15) and for each 10-d incremental delay in spring termination date (May 1–June 1). Biomass accumulation for cereal rye was best estimated using a thermal-based model that separated the effects of fall and spring heat units. Cultivars differed in their total biomass accumulation; however, once established, their growth rates were similar, suggesting the difference was mainly due to the earlier emergence of Aroostook rye. The earlier emergence of Aroostook rye may have explained its greater weed suppression than Wheeler, whereas the rye/hairy vetch mixture was intermediate between the two rye cultivars. Delaying cover-crop termination reduced weed density, especially for early- and late-emerging summer annual weeds in 2006. Yellow nutsedge was not influenced by cover-crop type or the timing of cover-crop management. We found that the degree of synchrony between weed species emergence and accumulated cover-crop biomass played an important role in defining the extent of weed suppression.

Adoption of reduced tillage practices have been driven by the need to enhance soil quality, minimize fi eld labor time, and scale up farm size. However, concerns about increased reliance on herbicides and demand for organically grown foods call for adoption of production practices that can reduce both tillage and herbicide use. Th is research study assessed the infl uence of planting and termination dates on mechanical cover crop control effi cacy to limit tillage and herbicide use using a roller/crimper. A thermal-based phenological model using growing degree days (GDD; base 4.4°C) was developed to predict cereal rye (Secale cereale L.) growth stage. Mechanical control of cereal rye increased as rye matured. Variations in cereal rye cultivar growth rates were observed; however, they responded similarly to rolling when terminated at the same growth stage. Consistent control was achieved at a Zadoks growth stage 61 (rye anthesis). A thermal-based phenological model separating the eff ects of heat units accumulated in the fall (Fall GDD ) from those accumulated in the spring (Spring GDD ) best predicted the phenological development of cereal rye. Predicting when cereal rye can be successfully controlled using a roller/crimper along with the use of the thermalbased phenological model should aid growers in decision-making regarding cereal rye planting and termination dates.

Summary Experiments comparing conventional and organic systems often report similar yields despite substantially higher weed abundance in the organic systems. A potential explanation for this observation is that weed–crop competition relationships differ between the two types of systems. We analysed weed and crop yield data from the Rodale Institute Farming Systems Trial (FST), which provides a unique 27-year dataset of a conventional (CNV) and two organic [manure (MNR) and legume (LEG)] soyabean (Glycine max (L.) Merr.) and maize (Zea mays L.) cropping systems. Average soyabean yields were similar between the MNR and CNV systems and only slightly reduced in the LEG system, whereas average maize yields did not differ among systems despite the two organic systems having more than four and six times greater weed biomass in soyabean and maize respectively. Plot-level weed biomass–crop yield relationships indicated that weed–crop competition differed between the two organic and CNV systems in maize, and was strongest in the CNV system, intermediate in the LEG system and weakest in the MNR system. These results suggest that organic cropping systems may be able to tolerate a greater abundance of weeds compared to conventional systems and that fertility management within organic systems may influence weed–crop competition.

Several mechanisms may contribute to the high species richness often reported in ectomycorrhizal (ECM) fungal communities, including spatial and temporal partitioning. Here, we focus on temporal partitioning. Using molecular methods, we determined the frequencies of occurrence of ECM fungal species detected as hyphae and ECM roots in the forest floor of a Pinus resinosa plantation during a 13-month period. We then used a novel statistical procedure to place the most frequently occurring ECM fungal species into groups distinguished by their patterns of relative frequency over time. Three groups with contrasting temporal patterns were distinguishable for fungal species detected as hyphae. Two groups were distinguishable for species detected as ECM roots. Our results support the hypothesis that temporal partitioning occurs among the species of ECM fungi in this community, but we did not address its causes, which may have involved interactions among species' physiological tolerances, temporal environmental variability, temporal patterns of root production, and variation in fungal genet lifespan. These interactions should be the subjects of future research.

Although the American eel Anguilla rostrata occurs in a variety of habitats over large geographic areas, little is known regarding the specific habitat relations that regulate eel distribution and abundance in freshwater streams. We evaluated the importance of 17 physical habitat, chemical, and biological variables in predicting eel density in five major river basins in Maryland. Because artificial structures impede eel migration in all five basins, only sites determined to be on unblocked streams or downstream of structures that significantly restrict eel passage were used in the analysis. Stepwise regression identified a model consisting of four variables—velocity–depth diversity, the log-transformed distance (km) to the Chesapeake Bay, the log-transformed density of noneel fishes, and the distance to a semipassable or impassable structure—as the best predictor of eel densities. When applied to a random subset of data not used for model development, the model correctly predicted 44.4% of eel de...

We examined the effects of beaver impoundments on the benthic macroinvertebrate assemblages of two small Appalachian streams, Mountain Run (Somerset County, Pennsylvania) and a tributary to Herrington Creek (Garrett County, Maryland). Benthic macroinvertebrate assemblages above the impoundments were compared with assemblages within the impoundments and 1 m, 10 m, and 100 m below the impoundments. The results of our study indicate that beaver affect both within-impoundment and downstream benthic macroinvertebrate assemblages. Taxonomic and functional changes in benthic macroinvertebrate assemblages of the beaver-altered streams were a result of direct (impoundment) and indirect (changes in temperature, water chemistry, plant growth) alterations of the stream environment.

Current land-use changes in eastern deciduous forests, such as fragmentation, may affect population sizes of native wildlife that may exacerbate declines in rare and endangered wildflower populations in the eastern deciduous forests. In this study, we examined the influence of herbivory by rodents (Peromyscus leucopus, Sciurus sp., and Tamias striatus) and white-tailed deer (Odocoileus virginianus) on the growth and survival of Turk's cap lily (Lilium superbum) planted in Virginia. Bulbs were planted in pairs and in patches. One plant per pair was protected from deer damage with a wire cage, and patches consisted of two, 10 and 25 bulbs planted within 0.04 ha. Rodents dug up and consumed 9% of all the bulbs planted, and fatal rodent damage was 3 times greater in successional than in upland hardwood and creek bottom habitats. White-tailed deer consumed the apical meristem of 28% of the unprotected lilies that emerged, reducing mean plant height and stopping growth and reproduction for that season. Deer and insects, but not rodents, damaged a greater proportion of plants emerging in small patches (1–2 plants/0.04 ha) than on larger patches (3–20 plants/0.04 ha). Therefore, when protecting remaining populations or restoring new populations of rare perennial wildflowers in the eastern deciduous forest, methods for protecting plants from herbivory by rodents and white-tailed deer should be considered.

We document the fire history and associated ecological changes of an old-growth forest stand in western Maryland, U.S.A. The study area is located on the side slopes of a ridge system (Savage Mountain). Twenty basal cross sections were obtained from old trees cut in 1986, which provided evidence of 42 fires from 1615 to 1958. Nine fires were recorded in the sample trees in the 17th century, 13 in the 18th century, 12 in the 19th century, and eight in the early to mid-20th century. However, there were no major fire years after 1930. The Weibull modal fire interval was 7.6 years. Oaks recruited consistently from the early 1600s to the early 1900s, but there was increased Acer rubrum L. and Betula lenta L. recruitment with fire suppression after 1930. Species recruitment patterns and long-term fire history reported in this study offer important direct support for the hypothesis that periodic fire played an important role in the historical development and perpetuation of oak forests of the mid-Atlantic region before and after European settlement.

In the field, the concentrations of several soluble carbohydrates in mycorrhizas of red pine varied seasonally. Fructose, glucose, sucrose and trehalose concentrations were negatively correlated with soil temperature, while myo-inositol and mannitol concentrations were positively correlated. The patterns for the concentrations of fungal carbohydrates (trehalose and mannitol) were consistent with their previously-reported functions. Trehalose may serve as a storage carbohydrate, accumulating during the winter when host carbohydrate is plentiful and when fungal growth is reduced. In contrast, mannitol may serve a translocatory role, increasing in concentration in warmer months when fungal growth is more rapid and when sporocarps are formed. The carbohydrates of six species of ectomycorrhizal fungi grown at room temperature and at reduced temperatures were also analysed to determine the extent to which seasonal variation in concentrations of fungal carbohydrates of mycorrhizas may be due to fungal acclimation to temperature. Variation in carbohydrate concentration occurred both among fungal species and due to cooling treatment. The variation due to cooling was relatively small, generally less than the variation among species, and less than the seasonal variation observed in field-collected mycorrhizas. This suggests that seasonal variation in the fungal carbohydrate trehalose in mycorrhizas could possibly be due to shifts in host carbohydrate supply rather than to independent shifts by the fungi in response to temperature. Production of a distinct pattern of carbohydrate concentrations by different ectomycorrhizal fungi suggests that fungal carbohydrates may be of taxonomic significance. This was further demonstrated using discriminant analysis of fungal carbohydrates.

We studied variation in forest floor thickness in four plantations of red pine (Pinus resinosa Ait.) which were similar in age, soil type and associated vegetation. The plantations were located (west to east) in the Clear Creek, Moshannon, Sproul and Tiadaghton State Forests of Pennsylvania, USA. A gradient in forest floor thickness exists across these plantations; the forest floor is thickest in the west and it becomes progressively thinner toward the east. Decomposition of imported litter increased from west to east, suggesting that the variation in forest floor thickness is related to variation in the rate of decomposition. Decomposition rates were related to saprotroph abundance. Variation in forest floor N and phenolic concentrations, in overall mycorrhiza density and in the relative proportions of three common mycorrhiza morphotypes could not explain the variation in decomposition rate. The P concentrations and pH of the forest floor were significantly lower at Clear Creek and Moshannon, where decomposition rates were lowest, compared to Sproul and Tiadaghton, where decomposition rates were most rapid. This suggests that P concentration and pH may have exerted some control on decomposition.

1. Our goal was to determine whether mycorrhizal infection of one generation of plants could influence the competitiveness of the subsequent generation. 2. We grew the offspring of mycorrhizal (M) and non-mycorrhizal (NM) Abutilon theophrasti plants together in dense populations in large boxes in a greenhouse. 3. Offspring of M plants were larger than offspring of NM plants. As the experiment progressed, the difference in size was magnified and self-thinning occurred. 4. Compared with offspring of NM plants, offspring of M plants had a twofold greater survival and collectively produced a total of nearly four times as many seeds. 5. We conclude that mycorrhizal infection of the parent generation can increase the competitive ability of the offspring.

The relationships among winter cover cropping, inoculum potential of vesicular-arbuscular mycorrhizal (VAM) fungi, and the growth and yield of a subsequent maize crop were investigated. In the first experiment, an autumn-sown winter wheat cover crop increased VAM fungal inoculum potential of a field soil as measured by an in situ maize bioassay during the following growing season. Infective extra-radical hyphal densities were significantly increased by cover cropping as interpreted from the effect of soil disturbance on infection of the maize bioassay plants. In a second experiment the following year, the winter wheat cover crop again increased VAM fungal inoculum potential as assessed by an in situ maize bioassay during the following growing season. Moreover, the degree of mycorrhizal infection of maize was correlated with maize growth and yield. This study suggests that the management of mycorrhizal fungi by cover cropping may be a useful practice in sustainable agriculture.

Mycorrhizal infection of Abutilon theophrasti Medic, increased seed quality and resultant offspring performance, but the improvement varied significantly with the timing of seed production. In general, offspring from mycorrhizal plants were superior to offspring from non-mycorrhizal plants, but the difference was greatest for the early cohort of seeds. Because increased seed size and quality can affect subsequent offspring competitive ability, increased variability in seed size and quality due to mycorrhizal infection may have an important impact on population dynamics of A. theophrasti.

We performed an experiment to determine factors affecting preference in the selection of seeds by Lumbricus terrestris L. Earthworms were given a menu consisting of seeds of nine plant species that were sorted into three size classes and sand particles that were sorted into the same three size classes. The experiment was conducted over a period of 84 days in worm beds under laboratory conditions. Seed and sand particles from the small (0.5–1.0 mm) size class were chosen four to one over seeds and sand in the intermediate (1.0–2.0 mm) size class. Seeds and sand particles in the intermediate size class were chosen 14 to one over seeds and sand particles in the large (2.0–2.5 mm) size class. Seeds were chosen two to one over sand in the small size class, six to one in the intermediate size class, and 15 to one in the large size class. Seeds with smooth surfaces were generally preferred over seeds with rough surfaces. Excavation of the bedding material at the conclusion of the experiment revealed that germination of seeds was occurring beneath the surface in chambers created by the earthworms, and that these seedlings were being grazed by L. terrestris.

SUMMARY The effects of inoculation with mycorrhizal fungi and phosphorus amendment on reproduction of Abutilon theophrasti Medic, were documented over two years in the field. In Year 1 all plots were thinned to a common and relatively low density (12 plants m−2). Mycorrhizal infection significantly increased capsule and seed production. Phosphorus amendment had little effect on these characters, possibly due to low soil moisture content. In Year 2 following natural recruitment, inoculated (M) plots were much more dense than uninoculated (NM) plots. In contrast with the results from Year 1, however, individual plains in M plots produced fewer capsules than those in NM plots in Year 2 because capsule production in Year 2 was density-dependent. Based on these results and others, we suggest that in monospecific stands of Abutilon, mycorrhizal infections have the greatest effects on fecundity at low densities. At higher densities, density-dependent forces may reduce the importance of mycorrhizal infections to reproductive effort of a single plant. Our results highlight the necessity of examining the effects of mycorrhizal fungi in natural populations and communities.

Northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.) were grown for two years in full sunlight (unshaded) or 20% of full sunlight (shaded) under either well-watered or drought conditions. There was a close association between evaporative flux (in situ) and leaf-specific conductivity (LSC) in stem segments of both species. Shaded, drought-stressed seedlings of both species had significantly reduced leaf area, evaporative flux, volume flow rate in xylem, flow velocity, potentially functional xylem area, and LSC than unshaded, well-watered seedlings. Reductions in LSC associated with drought or shade were similar for both species; and within a treatment, both species had similar LSC. Species differed in the manner of LSC adjustment to drought and shade. Reductions in leaf area associated with drought or shade were accompanied primarily by reductions in potentially functional xylem area for L. tulipifera, and by reductions in flow velocity for Q. rubra. These results suggest (1) the existence of a homeostatic balance between evaporative flux and LSC, (2) that species with widely different growth patterns and xylem anatomies may develop similar LSC within the same environment, and (3) a possible hydraulic basis for differences in habitat between ring- and diffuse-porous species.

Mirsky SB, Gallandt ER, Mortensen DA, Curran WS & Shumway DL (2010). Reducing the germinable weed seedbank with soil disturbance and cover crops. Weed Research50, 341–352. Summary Ecologically based weed management relies heavily on a greater integration of cultural and mechanical control tactics than conventional weed management. As such, management outcomes are more dependent on biotic interactions among the crop, weed and methods of management. In this study, we assessed the influence of soil disturbance and cover cropping on the germinable seedbank of Chenopodium album, Abutilon theophrasti and Setaria spp. across a range of initial weed seedbank densities. Cover crop system treatments ranged from greater reliance on tillage at one extreme, to a greater reliance on cover cropping to accomplish weed suppression at the other. In general, seedbank losses to germination were highest when soil disturbance was associated with cover cropping. Of the five cover crop systems (1 year duration), the summer fallow and the yellow mustard/buckwheat/winter rape mixture consistently decreased the weed seedbank. The magnitude of decline in these high disturbance systems reached complete depletion of the Setaria spp. germinable seedbank and an 85% and 80% reduction for C. album and A. theophrasti respectively. Both systems included tilling the soil three to four times throughout the growing season. In contrast, treatments which involved less soil disturbance had weed escapes that set seed in one or more site years. Cover crop systems that stimulated weed seed germination and where weeds were either suppressed by the cover crop or where subsequent tillage provided control, resulted in the greatest weed seedbank declines.

Two-year-old seedlings of green ash, Fraxinus pennsylvanica Marsh., representing five native populations from an east to west precipitation gradient, were grown under contrasting moisture regimes in the greenhouse. At midsummer and the end of the growing season, leaf areas, earlywood and latewood transverse areas, and several structural attributes of the xylem hydraulic system were compared between well-watered and drought-stressed seedlings. Xylem hydraulic capacity was essentially fixed by midsummer. Drought significantly reduced both earlywood and latewood production but had no significant effect on potentially functional xylem area (Apf) or flow velocity (v). The principal effect of drought on hydraulic architecture was a significant reduction in leaf area and therefore the ratios of potentially functional xylem area to unit leaf area (Apf to A1) and leaf specific conductivity (LSC). In contrast, populations differed significantly in all measured parameters, especially under drought conditions. Path analysis of LSC and its component variables revealed that treatment differences in LSC arose primarily through differences in A1; contributions from variation in Apf and especially flow velocity were relatively minor. In contrast, population variation in LSC could be attributed in roughly equal measure to variation in Apf and A1, and to a lesser degree to variation in flow velocity. The covariance between A1 and Apf was important for both treatment and population variation in LSC, suggesting a fundamental physiological linkage between these two aspects of plant hydraulic architecture. Among populations, high flow velocity tended to be associated with low Apf to A1 values, thereby minimizing population differences in the composite character LSC. Populations differed significantly in all attributes studied, in one environment or another, but those at either end of the precipitation gradient did not differ in several presumably important structural attributes. Although plant hydraulic architecture is genetically controlled and variable in green ash seedlings, its adaptive significance cannot be considered in isolation from other factors that control plant response to water stress. Key words: leaf specific conductivity, ecotypic variation, xylem structure.

We chemically restrained fishers (Martes pennanti) as part of a captive-management protocol designed to facilitate veterinary evaluation and treatment, and conditioning on a high-calorie diet before reintroduction in Pennsylvania. We compared the safety and efficacy of ketamine (KET) and medetomidine-ketamine (MED-KET) by monitoring immobilization intervals (induction time, down time, alert time, and recovery time) and physiologic responses (pulse rate, respiration rate, rectal temperature, blood pressure, oxygen saturation, and mean arterial pressure) during restraint. We administered MED-KET at 0.4 mg MED combined with 20.0 mg KET to males and at 0.2 mg MED combined with 10.0 mg KET to females. The x +/- SD dosages were MED 0.07 +/- 0.008 mg/kg + KET 3.7 +/- 0.5 mg/ kg for males and MED 0.07 +/- 0.007 mg/kg + KET 3.6 +/- 0.3 mg/kg for females. KET alone was administered at 100.0 mg to males and at 50.0 mg to females. resulting in x +/- SD dosages of 18.7 +/- 1.8 mg/kg for males and 19.2 +/- 2.2 mg/kg for females. Mean induction time did not differ between fishers restrained with MED-KET (4.6 min) and KET (4.5 min). However, compared with KET, MED-KET resulted in longer mean down time (36.2 vs. 142.2 min), alert time (40.8 vs. 146.8). and recovery time (81.1 vs. 199.4 min). Fishers that received MED-KET were mildly bradycardic and hypertensive compared with those that received KET. Although KET resulted in increased muscle tension and labored respiration, it would be effective for performing brief, noninvasive procedures for fishers because induction was rapid, recovery was short and calm, anesthesia was not profound, and physiologic response was generally expected on the basis of known drug pharmacology. Medetomidine-ketamine also immobilized fishers effectively, providing rapid induction, physiologic response typical to alpha2 agonism, calm recovery, and possibly a plane of anesthesia adequate for invasive procedures such as tooth removal or surgery.

A method for rapidly identifying feeding sites of thnps on leaves is described. After an impression of the leaf surface is made using cellulose acetate film and acetone solvent, feeding sites are easily counted on the impression under a light microscope. When sugar maple, Acer saccharum Marsh., leaves exhibiting different degrees of damage by pear thrips, Taeniothrips inconsequens (Uzel), were compared using the method, we observed a close relationship between the degree of macroscopic dan:age symptoms and number of feeding sites per unit leaf area. The origin of feeding sites was further verified under laboratory conditions on sugar maple leaf disks fed upon by western flower thnps, Frankliniella occidentalis (Pergande). Feeding sites were found only on Impressions of leaf disks which were exposed to thrips.

In this contribution we discuss several interactions between mycorrhizal fungi and their host plants. In particular we illustrate how plant communities may be affected by mycorrhizal fungi, and how mycorrhizal fungal communities may be affected by plants and plant cultural practices. The justification for the study of the mycorrhizal symbiosis at the level of the community is rooted in the fact that organisms in nature are usually assembled into interactive communities and do not exist as solitary entities. The function of the symbiosis must, therefore, be viewed in the context of communities. An important focus in ecological research in recent years has been to understand which factors regulate the structure and diversity of natural populations and communities. It has long been hypothesized that diversity may be crucial for maintaining productivity the and also the stability of ecosystems and recent experimental investigations support these ideas. Therefore, in this chapter we also discuss the role of diversity in arbuscular mycorrhizal (AM) fungal communities and the effect this may have on diversity of plant populations and communities. Although we draw extensively from the ecological literature, the concepts discussed herein are also relevant to horticulture, agronomy, forestry, and land reclamation. We believe that successful use of mycorrhizal fungi in these fields requires an essentially ecological perspective. This chapter deals primarily with the arbuscular mycorrhizal (AM) symbiosis. We call to the reader’s attention other recent reviews on related ecological treatments of the mycorrhizal symbiosis including those by St. John and Coleman (1983), Hetrick (1984), Loree and Williams (1984), Fitter (1990), Allen (1991), Brundrett (1991), Marx (1991), Read (1991a,b), Soderstrom (1991), Fahey (1992), Newsham et al. (1995), among others.

The effects of mycorrhizal fungi on plant growth and reproduction have come to light primarily from experiments in which host plants are grown as individuals, without interaction of other plants. In both natural ecosystems and agricultural settings, however, it is rare to find solitary plants. Plants normally exist as members of populations and communities, interacting with a number of adjacent individuals. Unfortunately, the relevance of mycorrhizal fungi to plants in these settings has not been frequently evaluated. Yet it is within natural communities that mycorrhizal associations evolved and, therefore, it is there that their biological significance must be assessed (Read 1991).

The Waveform and Sonicboom Perception and Response (WSPR) Program conducted a field study of subjective response to noise from multiple low-amplitude sonic booms. The team was led by Wyle and included researchers from Penn State, Tetra Tech and Gulfstream Aerospace Corp. The test exposed residents in the Edwards Air Force Base (EAFB) Housing area to two weeks of low-amplitude sonic booms while recording their responses via surveys. There were 52 participants divided across three response modes. The response instruments included Baseline Surveys, Single Event Surveys submitted each time a participant heard a boom, and Daily Surveys submitted at the end of each day. The analysis included assessments of single events and cumulative daily ratings of annoyance and categorical variables including loudness, interference, startle, vibration and rattle. The WSPR daily annoyance data was analyzed by computing percent highly annoyed (%HA) and relating it to the cumulative noise exposure and by relating the subjective annoyance rating directly to the daily noise exposure. The WSPR design was established to cover the full range of noise exposures and annoyance factors so that sufficient data would be gathered to facilitate analyses of %HA and noise metrics. The statistical analyses examining these relationships will be presented.

In this contribution we discuss several interactions between mycorrhizal fungi and their host plants. In particular we illustrate how plant communities may be affected by mycorrhizal fungi, and how mycorrhizal fungal communities may be affected by plants and plant cultural practices. The justification for the study of the mycorrhizal symbiosis at the level of the community is rooted in the fact that organisms in nature are usually assembled into interactive communities and do not exist as solitary entities. The function of the symbiosis must therefore be viewed in the context of communities. Although we draw extensively from the ecological literature, the concepts discussed herein are also relevant to horticulture, agronomy, forestry, and land reclamation. We believe that successful use of mycorrhizal fungi in these fields requires an essentially ecological perspective. This chapter deals primarily with the vesicular-arbuscular (VA) mycorrhizal symbiosis. We call to the reader’s attention other recent reviews on related ecological treatments of the mycorrhizal symbiosis including those by St. John and Coleman (1983), Hetrick (1984), Loree and Williams (1984), Fitter (1990), Allen (1991), Brundrett (1991), Marx (1991), Read (1991a,b), Soderstrom (1991) and Fahey (1992), among others.

We examined in the field the effect of the vesicular-arbuscular (VA) mycorhizal symbiosis on the reproductive success of Abutilon theophrasti Medic., an early successional annual member of the Malvaceae. Mycorrhizal infection greatly enhanced vegetative growth, and flower, fruit and seed production, resulting in significantly greater recruitment the following year. In addition, the seeds produced by mycorrhizal plants were significantly larger and contained significantly more phosphorus than seeds from non-mycorrhizal plants, an effect which may improve offspring vigor. Infection by mycorrhizal fungi may thus contribute to the overall fitness of a host plant and strongly influence long-term plant population dynamics.

We assessed the effect of feeding damage by pear thrips, Taeniothrips inconsequens Uzel (Thysanoptera:Thripidae), on gas exchange and water relations of sugar maple (Acer saccharum Marsh.) seedlings. Compared to undamaged seedlings, feeding punctures in the leaf epidermis of thrips-damaged seedlings decreased water use efficiency, increased leaf conductance to water vapor, and decreased predawn water potential. Under conditions of high soil water and high light intensity, carbon dioxide exchange rate (CER) was greater for thrips-damaged than undamaged seedlings because of greater CO(2) conductance through feeding punctures. Under conditions of low soil water, CER was lower for thrips-damaged than undamaged seedlings as a result of water stress. Carbon dioxide exchange rate at low light and low soil water was limited by non-stomatal factors, but no difference in non-stomatal limitation to CER was detected between thrips-damaged and undamaged seedlings. Leaf tissue water relations differed between thrips-damaged and undamaged seedlings and under high and low soil water conditions. The results suggest that the reduction in leaf area of thrips-damaged seedlings can be partially compensated by elevated CER under conditions of high light intensity and high soil water. However, high gas exchange rates through feeding punctures predisposes thrips-damaged seedlings to water stress that can reduce CER under conditions of low soil water.