Mixed Northern Hardwood Research Articles

Fog interception in spruce-fir and mixed northern hardwood forests of Great Smoky Mountains National Park, Southeast USA

Abstract: Fog interception is a significant component of the water balance of Southern Appalachian spruce-fir forests in the Southeast USA. Here, fog interception rates are quantified for spruce-fir and northern hardwood trees in Great Smoky Mountains National Park (GSMNP), Tennessee and North Carolina, as a precursor to examining how interspecific differences in fog interception could affect catchment water balances if there is widespread vegetation change from spruce-fir to hardwoods. A water-balance approach was implemented, based on paired open-site (rainfall) and beneath-canopy (throughfall) electronically recording tipping-bucket rain gauges that were in place in the spruce-fir zone of GSMNP from May to November 2021. Comparing identified fog interception events to actual conditions captured by a webcam, 90% of verifiable events had conditions that were either clearly or potentially favorable for fog interception. Estimated fog interception gain ranged from averages of 0.24 to 0.69 mm day−1, representing 3 to 8% of rainfall. Results are consistent with the expectation of higher fog interception gain for spruce and fir than for birch, the representative hardwood species. Quantification of fog interception rates provides valuable information about ecohydrological processes in ecologically significant Southern Appalachian spruce-fir forests.

Sugar maple (Acer saccharum) Seedling Bank Response to Storm Disturbance and Single Tree Selection Harvest in the Southern Keweenaw Peninsula, Michigan

This case study seeks to fill a critical knowledge gap regarding how natural wind disturbance affects stand and seedling bank diversity in mixed northern hardwood forests managed by single tree selection harvest methods. Contemporary timber harvests on state managed lands in Michigan's Upper Peninsula employ single tree selection cutting methods to promote more complex age structure in second growth stands dominated by sugar maple (Acer saccharum). However, concern exists that single tree selection harvest may result in lowered compositional diversity of seedlings as the low light conditions of small dispersed gaps exclude less shade tolerant species from gap regeneration. In July 2016 severe thunderstorms with winds in excess of 145 km/h (90 mph) caused extensive tree fall and canopy gap creation in second growth mixed northern hardwood forests in the southern Keweenaw Peninsula. We measured the species composition of overstory tree mortality and understory seedling regeneration in 14 storm gaps created in stands with and without previous single tree selection harvest. Storm gaps ranged in size from 125 to 1100 m2. American basswood (Tilia americana) was disproportionately wind-thrown. Robust seedling regeneration was released in all storm gaps, with sugar maple comprising more than 75% of mean seedling abundance, regardless of previous single tree selection harvest. Sugar maple and ironwood (Ostrya virginiana) comprised 80% of sapling abundance. Results indicate single tree selection of mixed northern hardwood stands does not exacerbate, but rather emulates, dense sugar maple regeneration found on unmanaged second growth sites.

Late middle Miocene Konan flora from northern Hokkaido, Japan

Plant macrofossils from the upper middle Miocene Konan Tuffaceous Sandstone and Mudstone Member of the Bifuka Formation, known as the Konan flora, northwest of Shibetsu City, Hokkaido, Japan, were taxonomically revised. A total of 31 taxa were recognized, which were assigned to 14 families and 19 genera, including a new fossil species, Salix palaeofutura sp. nov. The Konan flora includes three taxa of evergreen conifers, one perennial monocot herb and 27 deciduous dicots. The most abundant and common species were Fagus palaeojaponica, Acer subcarpinifolium, Acer protojaponicum, Picea sp. A and Cercidiphyllum crenatum, in addition to a number of species of the Betulaceae and Salicaceae. From the absence of evergreen angiosperms as well as the common occurrence of Fagus palaeojaponica, Picea, Acer and Betulaceae species, this flora was comparable to that seen in the modern Mixed Northern Hardwood Forest of East Asia, which is distributed in northernmost Honshu and extends toward lowland Hokkaido. On the basis of floral features, mode of occurrence, and the lithology of plant-bearing beds, the Konan flora was deemed to represent mountain to riverside vegetation with humid and cool temperate climatic conditions. In contrast to the early to late Miocene floras in Japan, the Konan flora belongs to the late Miocene–Pliocene Mitoku-type flora, with a few relict species from the early Miocene. The Konan flora represents one of the earliest occurrences of this type of flora, suggesting that floral modernization was initiated much earlier in areas with humid and cool temperate climate than previously thought.

Pyrolysis of hardwood soda-anthraquinone spent pulping liquor

A lignin-rich feedstock, soda-anthraquinone spent pulping liquor, was pyrolyzed in a kiln reactor. The liquor was prepared from mixed northern hardwood chips at a liquor-to-wood ratio of 3.5 L/kg, 16% effective alkali, and an H-factor of 1000 h. The spent liquor was pyrolyzed at 500°C as is, after oxygen oxidation, and with addition of sodium formate to determine the effect on bio-oil yield and product distribution. Contrary to bio-oil from sawdust, a clear phase separation of the liquid product into an aqueous layer and a denser organic layer is obtained. The predominant products found in the organic layer collected after pyrolysis are phenols with varying degrees of methylation and ethylation. The organic yield appears to go through a maximum (32 wt% on spent liquor organics) at around 25 wt% formate added on spent liquor dry solids and subsequently decreases at greater charges. Oxidation of the spent liquor prior to pyrolysis appears to have a detrimental effect on the organic yield.

Optimization study on acid hydrolysis of hardwood-derived hemicellulosic extract for alcohol fermentation using response surface methodology

Abstract In this study, the extraction conditions of hemicelluloses from mixed hardwoods have been tested. In particular, 3% total titrated alkaline (TTA) green liquor (GL) was used to dissolve certain hemicelluloses and lignin in a manner similar to black liquor extraction, but the pH was maintained at near-neutral conditions, so that oligosaccharides were not completely degraded into isosaccharinic acids. The effects of temperature, time, and acid concentration on the fermentable sugar yields for the extract during secondary hydrolysis were investigated. Chips of mixed northern hardwoods were cooked in a rocking digester at 160°C for 110 min in the GL at a concentration of 3% Na2 O-equivalent salts on dry wood. The mass of wood extracted into the GL extract was approximately 11.4% of the debarked wood mass, which resulted in a dilute solution of oligomeric hemicellulosic sugars. Dilute sulfuric acid hydrolysis was performed under the following conditions: 100°C–130°C, 2%–4% H2 SO4, and 20–120 min residence time. The maximum fermentable sugar concentration of xylose, mannose, and galactose (XyMaGa) obtained from the hydrolyzed extract was 5.5 g l-1, representing 91.7% of the maximum possible yield. A factorial design was used to study the effects of temperature and acid concentration on the maximum quantity of XyMaGa oligomers obtained in the extract during secondary hydrolysis. The maximum potential yield of XyMaGa reached 5.34 g l-1 at 130°C, 3.27% H2 SO4, and 50.2 min residence time.

Remote sensing of spring phenology in northeastern forests: A comparison of methods, field metrics and sources of uncertainty

Current remote sensing studies of phenology have been limited to coarse spatial or temporal resolution and often lack a direct link to field measurements. To address this gap, we compared remote sensing methodologies using Landsat Thematic Mapper (TM) imagery to extensive field measurements in a mixed northern hardwood forest. Five vegetation indices, five mathematical fits to model a continuous temporal response, and a suite of threshold estimates for “start of spring/season” (SOS) assessments were compared to field measurements of bud burst stage and hemispherical photo derived canopy structural metrics (transparency, leaf area index, greenness). Results indicated that a four-parameter logistic model based on at least five spring coverages of the Enhanced Vegetation Index (EVI) and a SOS threshold of 0.3 was most closely related to field metrics and most accurate in predicting the date of full leaf out. Plot level SOS was predicted with a mean absolute error of 11days for all species and elevation combinations, but improved to 9days for hardwood dominated plots and 7days for sugar maple dominated plots. Mean absolute error was improved to 8days when forest type (mixed, conifer hardwood) was used to refine predictions. The consistency of prediction errors across forest types indicates that while overall accuracy across pixels may be low, inter-annual comparisons of changes in phenology on a pixel basis may provide accurate assessments of changes in phenology over time. This was confirmed by application to seven years of independent phenology data predicted with 12days of mean absolute error. However, image availability will be a limiting factor in areas of frequent cloud cover.

Pseudotsuga tanaiiHuzioka from the earliest Miocene Shichiku Flora of northeast Japan: Systematics and ecological conditions

The earliest fossil record of the genus Pseudotsuga (Pinaceae) in Asia, Pseudotsuga tanaii Huzioka, was reexamined with additional materials of seeds, leaves, cones, and twigs from the earliest Miocene Shichiku Flora of the Joban area, northeast Japan. These specimens were restudied to better understand the relationship of these fossils with the extant and fossil species from Asia. Pseudotsuga tanaii not only shows characters common to the modern species in East Asia, but also yields similar characters seen in the American clade. Thus, it could be an ancestral taxon of the Asian clade, which appeared before the diversification of the East Asian species. In contrast to the extant Pseudotsuga species growing under warm-temperate climate conditions at middle to high elevations in the mountains, Pseudotsuga tanaii appears to have been associated with lowland vegetation growing at lake margins. Forest vegetation associated with the species is equivalent to the Mixed Northern Hardwood forest, which develops under cooler climatic conditions. The inferred habitat of Pseudotsuga tanaii and its age support the hypothesis based on molecular phylogeny and morphological analyses that the genus originated in the higher latitudes during the early Paleogene and migrated south following the climatic deterioration during the late Paleogene.

Acid Hydrolysis of Hemicellulose in Green Liquor Pre-Pulping Extract of Mixed Northern Hardwoods

Forest biomass is a promising resource for future biofuels and bioproducts. Pre-pulping extraction of hemicellulose by alkaline (Green Liquor) pretreatment produces a neutral-pH extract containing hemicellulose-derived oligomers. A near-term option for use of this extract is to hydrolyze the oligomers to fermentable monomer sugars. Chips of mixed northern hardwoods were cooked in a rocking digester at 160 degrees C for 110 min in Green Liquor at a concentration of 3% Na2O equivalent salts on dry wood. The mass of wood extracted into the Green Liquor extract was approximately 11.4% of the debarked wood mass, which resulted in a dilute solution of oligomeric hemicelluloses sugars. The concentration of the extract was increased through partial evaporation prior to hydrolysis. Dilute sulfuric acid hydrolysis was applied at conditions ranging from 100 to 160 degrees C, 2% to 6% (w/v) H2SO4, and 2- to 258-min residence time. The maximum fermentable sugar concentration achieved from evaporated extract was 10.7 g/L, representing 90.7% of the maximum possible yield. Application of the biomass pretreatment severity function to the hydrolysis results proved to offer a relatively poor prediction of temperature and reaction time interaction. The combined severity function, which incorporates reaction time, temperature, and acid concentration, did prove to provide a useful means of trading off the combined effects of these three variables on total sugar yields.

Early Miocene terrestrial climate inferred from plant megafossil assemblages of the Joban and Soma areas, Northeast Honshu, Japan

Five Early Miocene plant megafossil assemblages from two separate sequences in the Joban and Soma areas on the Pacific side of Northeast Japan, which are interpreted to have accumulated from vegetation in near-sea coastal lowland, are analyzed to discuss the temporal change of floral composition and causal change in terrestrial climate. The Mixed Northern Hardwood forest characterized by various species of deciduous woody dicotyledons and deciduous and evergreen conifers in Stage I (ca. 23.4 Ma) shifted gradually to a Mixed Broad-leaved deciduous forest (Stage II: ca. 21 Ma), a Mixed Broad-leaved Evergreen and Deciduous forest (Stage III: ca. 20 Ma) and a Notophyllous Broad-leaved Evergreen forest (Stages IV and V: ca. 16-17 Ma) with an appearance and subsequent increase in evergreen and deciduous species that favors warmer climatic conditions, and a decrease of taxa which inhabited cooler climates. These changes reflect an increase in mean annual temperature in the first half of the period and a decrease in mean annual range of temperature in the latter half, which were caused by mitigation of winter coldness. A quantitative analysis of mean annual temperature based on the leaf margin analysis also revealed a clear trend of increasing temperature. An abrupt change in temperature observed at the transition from Stages I to III, and warm climate during Stages IV to V can be correlated with the periods influenced by subtropical to tropical shallow-marine climate. A comparison between terrestrial and shallow-marine climates in the Joban and Soma areas probably indicates a synchronous response to climate change occurred during the Early Miocene.

A Cross-Site Comparison of Factors Influencing Soil Nitrification Rates in Northeastern USA Forested Watersheds

Elevated N deposition is continuing on many forested landscapes around the world and our understanding of ecosystem response is incomplete. Soil processes, especially nitrification, are critical. Many studies of soil N transformations have focused on identifying relationships within a single watershed but these results are often not transferable. We studied 10 small forested research watersheds in the northeastern USA to determine if there were common factors related to soil ammonification and nitrification. Vegetation varied between mixed northern hardwoods and mixed conifers. Watershed surface soils (Oa or A horizons) were sampled at grid or transect points and analyzed for a suite of chemical characteristics. At each sampling point, vegetation and topographic metrics (field and GIS-based) were also obtained. Results were examined by watershed averages (n = 10), seasonal/watershed averages (n = 28), and individual sampling points (n = 608). Using both linear and tree regression techniques, the proportion of conifer species was the single best predictor of nitrification rates, with lower rates at higher conifer dominance. Similar to other studies, the soil C/N ratio was also a good predictor and was well correlated with conifer dominance. Unlike other studies, the presence of Acer saccharum was not by itself a strong predictor, but was when combined with the presence of Betula alleghaniensis. Topographic metrics (slope, aspect, relative elevation, and the topographic index) were not related to N transformation rates across the watersheds. Although found to be significant in other studies, neither soil pH, Ca nor Al was related to nitrification. Results showed a strong relationship between dominant vegetation, soil C, and soil C/N.

Dynamics of large wood in an eastern U.S. mountain stream

Large wood (LW) is an important feature in many streams in northeastern North America, yet the dynamics (recruitment, movement, and export) of large wood remain largely undocumented for streams in this region. In this study we quantify the dynamics of LW in 400 m of a second-order, high gradient, boulder-dominated stream in the eastern Adirondack Mountains, NY. Characteristics and location of all LW (>1-m length, >10-cm diameter) in the 400-m study reach were initially recorded and pieces were individually tagged in November 2000. Subsequent surveys were conducted in late summer/fall of 2001, 2003, and 2004. Twenty-six% of the 112 pieces of LW initially tagged moved 5.0 m or more during the 4 years of this study. Mobile wood was, on average, shorter than non-mobile wood. Nearly all mobile wood was shorter than the 8.0-m bankfull width of the stream. From 2000 to 2004, 2.16 m 3 (0.54 m 3 100 m −1; 43 pieces) of LW entered the study reach and 0.7 m 3 (0.18 m 3 100 m −1; 13 pieces) left the stream. Retention of wood in debris dams was key to reducing potential export. For this stream, located within a second-growth mixed northern hardwood riparian forest that is approaching maturity, the net wood accumulation rate was estimated as ranging from 0.09 to 0.15 m 3 100 m −1 year −1. Our data support previous observations that LW length strongly influences its potential to move in high gradient streams, though debris dams can reduce LW movement rates and movement distances for wood of all sizes.

Flux estimates and OH reaction potential of reactive biogenic volatile organic compounds (BVOCs) from a mixed northern hardwood forest

Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including isoprene, monoterpenes (MT), and sesquiterpenes (SQT) were determined at the University of Michigan Biological Station for the tree species red maple ( Acer rubrum), red oak ( Quercus rubra), paper birch ( Betula papyrifera), white pine ( Pinus strobus), and big tooth aspen ( Populus grandidentata). These emission rates were combined with detailed biomass distribution and meteorological data and incorporated into the canopy model, model of emissions of gasses and aerosols from nature (MEGAN), for estimating whole-canopy fluxes of isoprene. The modeled half-hour fluxes ( mg C m - 2 h - 1 ) and cumulative seasonal fluxes ( mg C m - 2 ) compared favorably with results from direct, canopy-level eddy covariance (EC) isoprene measurements; modeled cumulative seasonal flux deviated less than 30% from the EC results. Significant MT emissions were found from four of the five tree species. MT emissions from three of these were both light- and temperature-dependent and were approximately one order of magnitude greater than light-independent MT emissions. SQT emissions were identified from three of the five tree species. The model was modified to incorporate SQT and both light-dependent and light-independent MT emissions for determining fluxes. Isoprene comprised > 95 % of the total terpenoid flux with MT and SQT comprising 4% and 0.3%, respectively. The average cumulative fluxes (in mg C m - 2 ) from June through September were 2490 for isoprene, 105 for MT, and 7 for SQT. A simple box model analysis was used to estimate the contribution of the isoprene, MT, and SQT emissions to the total OH reactivity. These results confirm that isoprene dominates OH reactions especially during daytime hours. Emissions of reactive MT and SQT increase the BVOC+OH reactivity, but are still lower than estimates of BVOC fluxes at this site necessary for affecting OH reactivity to the significant degree suggested by recent reports.

Watershed Nitrogen and Mercury Geochemical Fluxes Integrate Landscape Factors in Long-term Research Watersheds at Acadia National Park, Maine, USA

This paper is an overview of this special issue devoted to watershed research in Acadia National Park (Acadia NP). The papers address components of an integrated research program on two upland watersheds at Acadia NP, USA (44 degrees 20' N latitude; 68 degrees 15' E longitude). These watersheds were instrumented in 1998 to provide a long-term foundation for regional ecological and watershed research. The research was initiated as part of EPA/NPS PRIMENet (Park Research and Intensive Monitoring of Ecosystems Network), a system of UV-monitoring stations and long-term watershed research sites located in US national parks. The initial goals at Acadia NP were to address research questions about mercury, acid rain, and nitrogen saturation developed from prior research. The project design was based on natural differences in forests and soils induced by an intense wildfire in one watershed in 1947. There is no evidence of fire in the reference watershed for several hundred years. We are testing hypotheses about controls on surface water chemistry, and bioavailability of contaminants in the contrasting watersheds. The unburned 47-ha Hadlock Brook watershed is 70% spruce-fir mature conifer forest. In contrast, burned 32-ha Cadillac Brook watershed, 4 km northeast of the Hadlock watershed, is 20% regenerating mixed northern hardwoods and 60% shrub/rocky balds. Differences in atmospheric deposition are controlled primarily by forest stand composition and age. The watersheds are gauged and have water chemistry stations at 122 m (Cadillac) and 137 m (Hadlock); watershed maximum elevations are 468 and 380 m, respectively. The stream water chemistry patterns reflect, in part, the legacy of the intense fire, which, in turn, controls differences in forest vegetation and soil characteristics. These factors result in higher nitrogen and mercury flux from the unburned watershed, reflecting differences in atmospheric deposition, contrasting ecosystem pools of nitrogen and mercury, and inferred differences in internal cycling and bioavailabilty.

Warm climate in the late Miocene of the south coast of Alaska and the occurrence of Podocarpaceae pollen

A study of the Homerian type section in the upper Beluga Formation (Upper Miocene) of the Kenai Group of southern Alaska has yielded two surprising discoveries: (1) warmth‐loving taxa and (2) the presence in Alaska of a ‘new’ gymnosperm family, Podocarpaceae. A well‐preserved pollen and spore flora is present in Upper Miocene coal beds of the Kenai lowland, near Homer, Alaska. Stump horizons, abundant wood fragments, wood grain, and amber within the coal attest to a forested swamp. Pollen assemblages from the Homerian type section include elements of both Mixed Northern Hardwood and warm‐temperate Mesophytic forests and are far richer than the flora previously defining the Homerian type section, which had suggested a less diverse, cooler assemblage. Within the Homerian type section, the flora exhibits no definite taxonomic chronology; in general, Alnus dominates, with up to 45% of the total counts, followed by Pinaceae and Taxodiaceae pollen types (30 to 35%) and thermophiles (c. 14%). At least 36 genera are represented, including Carya type, Corylus, Ilex, Juglans, Myrica, Ostrya/Carpinus, Pterocarya, Quercus/Quercus‐type, and Ulmus/Zelkova, eight dicot genera have not previously been reported from the type Homerian. Presence of these hardwoods in moderate to minor amounts suggests that the climate during the Homerian (Late Miocene) was only slightly cooler than that of the Seldovian (Early to Middle Miocene). Unexpectedly, Dacrydium and Podocarpus are present as minor elements in most of the samples. They apparently coexisted with the other Miocene taxa, because the pre‐Paleogene Kenai‐Chugach terrane to the southeast, which supplied sediments to the Kenai Group, is mostly of oceanic plate provenance and is unlikely to have been the source of the pollen. A uniform orange fluorescence of all the pollen, including the podocarps and any potentially reworked pollen, also suggests a contemporaneous origin for all the taxa. The flora from the Homerian type section may precede or coincide with uplift of the Alaska Range to the north. Thus, further comparison with Homerian taxa at localities north and south of the Alaska Range will be important as it may reveal a possible rain shadow effect.

Cerulean warbler use of regenerated clearcut and two-age harvests

We examined use of 2 silvicultural treatments (clearcut and two-age harvests), 15-18 years post-harvest by cerulean warblers (Dendroica cerulea) in mixed mesophytic and northern hardwood forests of the Allegheny Mountain region in West Virginia. Cerulean warbler abundance and occurrence were greater in 70-80-year-old mature forests than in 15-18-year-old clearcuts. Although abundance did not differ statistically between clearcut and two-age treatments, it was almost 5 times greater in the two-age treatments, likely because they provided a more complex canopy structure. Abundance of cerulean warblers in unharvested periphery stands adjacent to clearcut and two-age harvests was similar to that in unharvested control stands, suggesting that small harvests within mature forest do not negatively impact cerulean warbler abundance in the remaining forest, only within the clearcut harvests themselves.

WARM CLIMATE IN THE LATE MIOCENE OF THE SOUTH COAST OF ALASKA AND THE OCCURRENCE OF PODOCARPACEAE POLLEN

Abstract A study of the Homerian type section in the upper Beluga Formation (Upper Miocene) of the Kenai Group of southern Alaska has yielded two surprising discoveries: (1) warmth-loving taxa and (2) the presence in Alaska of a ‘new’ gymnosperm family, Podocarpaceae. A well-preserved pollen and spore flora is present in Upper Miocene coal beds of the Kenai lowland, near Homer, Alaska. Stump horizons, abundant wood fragments, wood grain, and amber within the coal attest to a forested swamp. Pollen assemblages from the Homerian type section include elements of both Mixed Northern Hardwood and warm-temperate Mesophytic forests and are far richer than the flora previously defining the Homerian type section, which had suggested a less diverse, cooler assemblage. Within the Homerian type section, the flora exhibits no definite taxonomic chronology; in general, Alnus dominates, with up to 45% of the total counts, followed by Pinaceae and Taxodiaceae pollen types (30 to 35%) and thermophiles (c. 14%). At least 3...

Comparison of methods for sampling Thysanoptera on basswood ( Tilia americana L.) trees in mixed northern hardwood deciduous forests

Canopy arthropods play integral roles in the functioning, biodiversity, and productivity of forest ecosystems. Yet quantitative sampling of arboreal arthropods poses formidable challenges. We evaluated three methods of sampling the introduced basswood thrips, Thrips calcaratus Uzel (Thysanoptera: Thripidae), from the foliage of basswood canopies with respect to statistical variability and practical considerations (legal, economic and logistical accessibility). All three methods involved removal of foliage, which was performed using a pole-pruner, shotgun, and certified tree-climber. We also tested a fourth method, in which the tree-climber enclosed samples in a plastic bag to estimate losses that occur when branches fall to the ground, even though this is often not practical. The climber plus bag and pole-pruning methods obtained the highest numbers of thrips. Mean number of larval thrips did not vary significantly among the three main sampling methods. Site had a stronger effect on the number of larval thrips obtained than on the number of adults. A significant method by site interaction was observed with adults but not larvae. Significant collection date (which corresponds to thrips life stage) by site interaction was also observed. We regressed sampling methods to determine if the number of thrips obtained using one method can be used to predict the number obtained with another. Tree-climber and pole-pruner data were highly predictive of each other, but shotgun data cannot be used to estimate other methods. Pole-pruning is the most cost-effective and legally permissible technique, but is limited to trees with accessible lower branches. The shotgun method is cost-effective and useful in sampling trees at least up to 27 m, but is prohibited close to human activity. The tree-climber is effective and broadly applicable, but incurs the highest costs. This study shows the need to evaluate a variety of techniques when sampling arboreal insects with respect to predictability, pragmatics and life stages.

Effects of forest management practices on the diversity of ground-occurring beetles in mixed northern hardwood forests of the Great Lakes Region

Ground-occurring Coleoptera were sampled over 2 years using pitfall traps in 23 northern hardwood or eastern hemlock-dominated sites representing even-aged, uneven-aged, or old growth forests. Overall, 65,586 individuals were obtained, representing 33 families and 192 species. Carabids comprised 54% of the total catch in 1996, when all the families were tallied. There was little variation in the number and relative abundance of carabid species caught between seasons. No differences in overall species richness or abundance were observed among forest management regimes or habitat types. However, there were substantial differences in species composition. Thirteen species showed significant habitat associations among the five forest management regimes, and 21 species were associated with specific habitat features of the sites, such as dominant tree species or canopy structure. More species (16) were affected by the presence of forest management than by tree species dominance (6) or canopy structure (5). Harpalus fulvilabris, Pterostichus coracinus, Carabus nemoralis, Glischrochilus siepmanni, Nicrophorus orbicollis, and Nicrophorus sayi were more commonly caught in managed than in old growth forest sites, while Carabus sylvosus, Platynus decentis and Oiceoptoma novaboracensis were more commonly associated with old growth sites. Calosoma frigidum and Necrophila americana were associated with northern hardwood sites, while Platynus decentis was significantly associated with sites dominated by eastern hemlock. Calosoma frigidum, Necrophila americana, and Nicrophorus vespilloides were more common in even-aged sites, while a lampyrid and a leiodid morphospecies were more common in sites with an uneven-aged canopy structure. The importance of microsite features was reflected in the high variability observed among sites and among traps within sites. Results indicate that conservation of a range of forest types is required in order to maintain the diversity of ground-occurring beetles on a regional scale. This will be quite challenging, since forest types such as old growth hemlock-hardwood are rare across the landscape due to habitat fragmentation and logging.

Underestimation of dry deposition by throughfall in mixed northern hardwood forests

Throughfall and catchment mass balance approaches were used to estimate dry deposition inputs of SO 4 and Cl to the Bear Brook in Maine for the period November 1988–November 1992. For throughfall, dry deposition of SO 4 and Cl averaged 320 and 261 eq ha −1 year −1, respectively, or 0.9 and 1.5 times the input in precipitation, respectively. The equivalent values for the catchment gave dry deposition of SO 4 and Cl as 616 and 380 eq ha −1 year −1, respectively, or 1.7 and 2.2 times the input in precipitation, respectively. The lower estimates obtained by the canopy mass balance method are primarily attributed to an underestimation of the importance of conifers in intercepting dry and occult deposition, particularly in mixed hardwood-softwood canopies such as the Bear Brook. Although net throughfall is commonly used to estimate dry and occult deposition in forested catchments, dry deposition may be underestimated, particularly in uneven-aged, mixed hardwood-softwood forests characterized by occasional superdominant conifers. The uneven canopy architecture of such forests increases its aerodynamic roughness and thus its efficacy in capturing dry deposition. Mixed-species forests, resulting from both natural and anthropogenic disturbance, are a common component of the landscape throughout much of New England.

Comparative analysis of data acquired by three narrow-band airborne spectroradiometers over subboreal vegetation

Calibrated radiance data were acquired with three airborne sensor systems on 8 September 1990 over a northern forest as part of the Forest Ecosystem Dynamics Multisensor Aircraft Campaign. The spectral data were acquired nearly simultaneously under extremely clear sky conditions with NASA's AVIRIS and ASAS imaging spectroradiometers, and an SE-590 spectroradiometer mounted on a NASA UH-1B helicopter. After atmospheric corrections were applied to these data, intercomparisons of nadir reflectance factor measurements from each of these sensors were made for four important vegetation communities including a bog and individual forest stands dominated by spruce ( Picea sp.), eastern hemlock ( Tsuga canadensis), and mixed northern hardwoods (dominated by Acer sp., Populus sp., and Betula sp.), respectively. The reflectance factor spectra from the different instruments were comparable for each of these cover types, suggesting the possible interchangeable use of the three datasets over comparable wavelength regions. These comparisons also serve to graphically illustrate the importance of applying atmospheric corrections to such data, even if acquired under extremely clear sky conditions. This remote sensing data set appears suitable for assessing the applicability of multistage, multisensor data in largescale ecological research.