Presettlement Forest Research Articles

Forest Transformation Following European Settlement in the Saguenay-Lac-St-Jean Valley in Eastern Québec, Canada

Human activities have changed forest composition of northeastern North America since European settlement by increasing the importance of pioneer shade-intolerant species, at the expense of shade-tolerant and long-lived species. This study used tree taxa lists from land survey archives (1842–1935) to document the pre-settlement forest composition in a heavily transformed region at the temperate-boreal interface in eastern Quebec (Canada). Pre-settlement forests were dominated by a spruce-fir-white birch assemblage. Two additional assemblages were characterized by high relative frequency of the fire-adapted jack pine and poplar, suggesting that fire was an important factor of pre-settlement forest dynamics. Comparison with modern forest inventories (1980–2010) showed that trembling aspen, jack pine and red maple increased to the detriment of spruce, yellow birch, and white and red pines. The spruce-fir-white birch assemblage is now confined to high elevations and steep slopes, while the jack pine assemblage has extended its distribution and strengthen its association with sandy deposits. Surveyors’ fire observations revealed a high fire activity during the settlement period (1842–1971) and human ignitions were probably the predominant cause. While settlement fires are a likely explanation for the post-settlement increase of jack pine and trembling aspen, industrial logging and land clearing are important factors that could explain the decline of spruce and pines (red and white). Ecosystem-based forest management should aim to increase spruce frequency and dominance over disturbance-adapted (shade intolerant and fast-growing) species, and to restore yellow birch, cedar, white, and red pines in the plains sector where forest transformation has been the most important.

Composition Changes in the Boreal Mixedwood Forest of Western Quebec Since Euro-Canadian Settlement

Colonisation of eastern North America has generated significant modifications in forest composition. In regions highly influenced by human activity, historical ecology can be used to reconstruct pre-settlement forest composition. In this study, we reconstruct the composition of the pre-settlement (1909-1937) forest of a 4,134 km2 sector of the boreal mixedwood forest using early land survey archives. The pre-settlement composition was compared with modern composition using recent eco-forest inventories (1980-2008), and the influence of surficial deposits types on the spatial structuration of compositional changes was assessed. During the pre-settlement period, the landscape was primarily dominated by spruce, which was evenly distributed across surficial deposit types. Trembling aspen, although frequent, rarely dominated stands. In contrast, the present-day landscape is dominated by trembling aspen, notably on clay and till deposits. In general, conifers have undergone a severe reduction in frequency. Spruce and pine forests are today mainly restricted to organic and sandy surficial deposits compared to their distribution during the pre-settlement period. Composition changes observed in western Abitibi are essentially the results of fires and forest harvesting, but surficial deposits have contributed in structuring the current abundance and spatial distribution of the different taxa. In the context of sustainable forest management, considerable effort should be deployed to restore conifer dominance in the region, notably on the fertile deposits that appear particularly susceptible to composition changes.

Integrating Multiple Sources to Reconstruct the Pre- and Early Postcolonial Forests of the Chesapeake: 1588–1838

Multiple historic sources were used to reconstruct the forests of the Chesapeake at the time of European colonization. Early written records (1588–1699) show forests composed of hardwoods and conifers; the most commonly reported hardwoods are oak (100% occurrence in the texts), followed by walnut (93.3%), sassafras (86.7%), mulberry (80.0%), ash (60.0%), and chestnut (60.0%), and the most commonly reported conifers cedar (92.9%), pine (86.7%), and cypress (73.3%). It is likely that these reports focused on trees of economic value. John Smith’s 1612 map of the Chesapeake shows a forest composed of ca. 50:50 ratio of hardwoods to conifers. Hardwoods could not be identified further, while conifers could be grouped into what appear to be pine, cedar, and baldcypress. Advertisements of land for sale or lease (1751–1838) show a forest primarily composed of hardwoods (86.5%), predominantly oak, with a small conifer component (13.5%). Forest cover averaged 61.5% and ranged from 19.7 to 100%. There is no relationship between percentage of forest cover and date of advertisement, indicating little change over that time frame on settled land. Advertisements of wood for sale or wanted also indicate a forest dominated by oak. Oak was the primary material for ship construction and barrel making, as well as the major fuel source. Witness tree records from the seventeenth century (the earliest reported) on Maryland’s Eastern Shore show that a mature Oak–Pine forest dominated the pre-settlement forest, with white oak (Quercus alba) the most common hardwood. Currently a Pine–Oak–Maple forest dominates the landscape, with pines the dominant conifer and maple, particularly red maple (Acer rubrum), the dominant hardwood, mainly due to fire suppression in the twentieth century.

Climate change will affect the ability of forest management to reduce gaps between current and presettlement forest composition in southeastern Canada

Forest landscapes at the boreal–temperate ecotone have been extensively altered. Reducing the gap between current and presettlement forest conditions through ecosystem-based forest management (EBFM) is thought to enhance ecological integrity. However, climate change may interfere with this goal and make these targets unrealistic. We evaluated the impacts of climate change on the ability of EBFM to reduce discrepancies between current and presettlement forest conditions in southeastern Canada. We used early-land-survey data as well as projections from a forest landscape model (LANDIS-II) under four climate change scenarios and four management scenarios to evaluate future discrepancies between presettlement forest conditions and future forest landscapes. By triggering swift declines in most late-succession boreal conifer species biomass, climate change would greatly reduce the ability of forest management to reduce the gap with presettlement forest composition, especially under severe anthropogenic climate forcing. Scenarios assuming extensive clearcutting also favor aggressive competitor species that have already increased with high historical harvest levels (e.g., poplars, maples). EBFM would still be the “less bad” forest harvesting strategy in order to mitigate composition discrepancies with the presettlement forests, though it is likely to fail under severe climate forcing. In this latter case, one might thus question the relevancy of using presettlement forest composition as a target for restoring degraded forest landscapes. As such, we advocate that managers should relax the centrality of the reference condition and focus on functional restoration rather than aiming at reducing the gaps with presettlement forest composition per se.

Topography and soils-based mapping reveals fine-scale compositional shifts over two centuries within a central Appalachian landscape

When public lands were surveyed in the U.S., “witness trees” were often recorded to facilitate the relocation of property boundaries, and these records provide a snapshot of forest conditions prior to Euro-American settlement and land clearing. This study utilizes witness trees and present-day plot data to explore long-term vegetation changes at a regional scale. Landscape classes for a 5000 km2 study area in Appalachian Ohio were defined by slope, aspect, topographic position, soil pH, and available water capacity. Cluster analysis and ordination revealed topo-edaphic patterns in the presettlement (c. 1800) and present-day forests, based on 5765 witness trees and 3249 contemporary trees occurring on 547 Forest Inventory and Analysis (FIA) subplots. Mesophication is evident, as the oak-hickory presettlement forest is now dominated by maple-poplar. Size-class analysis suggests the presettlement forest also experienced mesophication following xeric conditions of the preceding centuries. In both presettlement and contemporary forests, ridges form distinctive communities compared to slopes and valleys, although topographic distinctiveness is now more prevalent. Several taxa revealed changes in site affinities over the past two centuries; shifts in their realized niches suggest mesophication acts through diverse individualistic responses to a multiple set of interacting drivers. Specifically, regionally documented changes in land use, drought, N deposition, and fire at the time of the original surveys lead to altered competitive relationships.

Sharp Savanna-forest Transitions in the Midwest Followed Environmental Gradients but are Absent from the Modern Landscape

Historically, closed eastern forests transitioned into open savannas and prairies in the U.S. Midwest, but this transition is poorly understood. To investigate the eastern boundary of the prairie-forest ecotone, we conducted a case study of historic and modern vegetation patterns of the Yellow River watershed in northwest Indiana. Historic vegetation came from the Public Land Survey notes collected in the early 1800s, whereas modern vegetation came from the Forest Inventory Analysis and USGS National Land Cover Database. We mapped vegetation data using GIS to reconstruct the region's past and current forest composition and structure. We also mapped climate, topography, and soil composition across the watershed to investigate the relationship between historic vegetation and environmental gradients. We found a sharp transition in the presettlement forest structure and composition, with dense deciduous forests in the eastern portion of our study area and open oak savannas in the west. The savanna ecosystem dominated in sandy well-drained soils and was at a slightly lower elevation than the adjacent closed forest. Modest environmental changes accompanied major vegetation changes in the past, which might suggest fire and hydrological patterns helped maintain the sharp ecotone. By contrast the modern forest shows no difference in tree density and composition across the watershed, which is consistent with major land use and hydrology changes in the watershed since settlement. On the modern landscape, land that was historically closed forest now has higher agricultural productivity compared to land that was historically savanna, whereas the historic savanna currently supports more mesic forest. These results suggest the environmental gradient continues to subtly shape the landscape. Though land use change has largely removed the closed mixed hardwood forests and oak savannas from this area, a better understanding of the historic vegetation and the conditions that supported it can help inform land management and restoration, as well as reveal ecological processes that drive vegetation transitions.

Predicting historic forest composition using species lists in presettlement land survey records, western New York

AbstractQuestionsDo the species lists (SLs) of presettlement land surveys, little used though available for over two million km in the USA, provide useful information on historic forest composition? Do the bearing trees (BTs) and SLs of pre‐settlement land surveys record similar species and relative abundances? Are relative abundances more similar when species in an SL are given equally weighted relative abundances or rank‐weighted relative abundances?LocationTemperate broadleaf forest, western New York, US.MethodsBT and SL data were obtained for the 3 172 953 m of lines surveyed in 1797–9 by the Holland Land Company. The presence and relative abundance of 8394 BTs were compared with 11 192 unique taxon mentions within SLs. Comparisons were made for individual taxa and whole communities, and at the scales of individual line segments and whole town lines. The influence of equal weighting and rank weighting of the SLs on the comparisons was assessed.ResultsThe SLs on a line segment typically recorded more taxa than did the BTs. The species present in BTs and SLs on individual line segments were indicated by Cohen's Kappa to have ‘substantial agreement.’ Correlations between BTs and SLs of all taxa on the same town line increased with the number of BTs and SLs on the town line, and when the relative abundances of SL taxa were modelled using rank weighting rather than equal weighting. Correlations between BTs and SLs for individual taxa were higher for taxa that had more BTs. Correlations between BTs and SLs were also higher when the relative abundances of SL taxa were modelled using rank weighting vs equal weighting.ConclusionsSLs capture greater detail of presettlement forest composition than do BTs. The relative abundance of a taxon mentioned in a presettlement land survey SL can be meaningfully predicted using its rank in an SL and application of a rank weighting model.

Jeffrey Pine Seed Dispersal in the Sierra San Pedro Mártir, Baja California, Mexico

The Sierra San Pedro Mártir (SSPM) in northern Baja California, Mexico, is a remote mountain at the southern edge of the California Floristic Province, a vegetation type that includes the Sierra Nevada of California and western Nevada. Unlike most forests in the southwestern United States, the forests of the SSFM have never been logged and have experienced only light grazing in recent years, and wildfires have not been suppressed until recent decades. The SSFM represents one of the best examples of an intact presettlement forest in the California Floristic Province. We investigated the mode of seed dispersal of Jeffrey pine (Pinus jeffreyi) in the SSPM, and compared it to that from the eastern slope of the Sierra Nevada, to determine how this process might differ between nearly pristine and heavily altered forests. We found that seed dispersal appears to occur by the same means in both forests (i.e., scatter hoarding of seeds by rodents), but that seedling establishment is much less successful in the SSPM. We considered several hypotheses for why this difference might exist, including the size of seed crops, fire regimes, climate change, grazing by domestic ungulates, and lack of facilitation by shrubs (i.e., nurse plants), but none of these explanations appears adequate to account for the difference. Instead, we suggest that the slow rate of seedling establishment at the SSPM is due to a greater consumption of seeds cached by California chipmunks (Tamias obscurus), who experience a relatively long period of euthermic winter activity in the warm climate of the SSPM. This greater consumption leaves few seeds to germinate. Future studies should test the relative importance of these alternative causes for low seedling recruitment at the SSPM.

Origins of the Chicago Urban Forest: Composition and Structure in Relation to Presettlement Vegetation and Modern Land Use

Urban forests provide important ecosystem services, but species composition and canopy structure influence provisioning of these services and long-term stability of the urban canopy. Two landscape-scale data sets (presettlement land surveys and an urban tree census) were used to explore relationships among modern land use, presettlement vegetation, and urban forest canopy structure, size structure, and composition in the Chicago, Illinois, U.S., metropolitan region. Presettlement vegetation and modern land use combined to influence urban forest composition and structure. Modern forested areas with high native species dominance, canopy cover, and structural complexity were associated with forest (rather than prairie) vegetation in the presettlement landscape. Oaks (Quercus spp.), which dominated presettlement forests and provide high ecosystem service value because of their large stature and wildlife value, were strongly associated with presettlement forest areas and modern natural areas. The Chicago region is in a transitional state where composition and structure of larger size classes is heavily tied to pre-urban vegetation. In the future, this landscape is likely to experience a shift in dominance from oaks to smaller-statured, shorter-lived non-native and opportunistic species. This shift, along with climatic change and introduction of exotic pests, may result in an urban forest with reduced potential to provide important ecosystem services.

Comparing modern and presettlement forest dynamics of a subboreal wilderness: Does spruce budworm enhance fire risk?

Insect disturbance is often thought to increase fire risk through enhanced fuel loadings, particularly in coniferous forest ecosystems. Yet insect disturbances also affect successional pathways and landscape structure that interact with fire disturbances (and vice-versa) over longer time scales. We applied a landscape succession and disturbance model (LANDIS-II) to evaluate the relative strength of interactions between spruce budworm (Choristoneura fumiferana) outbreaks and fire disturbances in the Boundary Waters Canoe Area (BWCA) in northern Minnesota (USA). Disturbance interactions were evaluated for two different scenarios: presettlement forests and fire regimes vs. contemporary forests and fire regimes. Forest composition under the contemporary scenario trended toward mixtures of deciduous species (primarily Betula papyrifera and Populus spp.) and shade-tolerant conifers (Picea mariana, Abies balsamea, Thuja occidentalis), with disturbances dominated by a combination of budworm defoliation and high-severity fires. The presettlement scenario retained comparatively more "big pines" (i.e., Pinus strobus, P. resinosa) and tamarack (L. laricina), and experienced less budworm disturbance and a comparatively less-severe fire regime. Spruce budworm disturbance decreased area burned and fire severity under both scenarios when averaged across the entire 300-year simulations. Contrary to past research, area burned and fire severity during outbreak decades were each similar to that observed in non-outbreak decades. Our analyses suggest budworm disturbances within forests of the BWCA have a comparatively weak effect on long-term forest composition due to a combination of characteristics. These include strict host specificity, fine-scaled patchiness created by defoliation damage, and advance regeneration of its primary host, balsam fir (A. balsamea) that allows its host to persist despite repeated disturbances. Understanding the nature of the three-way interaction between budworm, fire, and composition has important ramifications for both fire mitigation strategies and ecosystem restoration initiatives. We conclude that budworm disturbance can partially mitigate long-term future fire risk by periodically reducing live ladder fuel within the mixed forest types of the BWCA but will do little to reverse the compositional trends caused in part by reduced fire rotations.

A comparison of presettlement and modern forest composition along an elevation gradient in central New Hampshire

Tree species composition is influenced not only by edaphic and climatic factors but also by natural and human-caused disturbances. To understand interactions among these influences, we compared forest species composition data from the time of European settlement with modern data. We derived elevation data for 2529 trees mapped by early land surveys (1770–1850) across a 1000 m elevation gradient in central New Hampshire and compared these with modern data (2004–2009) from the Forest Inventory and Analysis program (123 plots containing 2126 trees) and from permanent plots representing case studies of different land-use histories. Spruce and beech are much less abundant today at all elevations than they were prior to settlement, while maples and birches have increased. Fir, hemlock, pines, and oaks have changed little in distribution, although pines and oaks increased in abundance somewhat. Land-use history (agriculture below 500 m and cutting of various intensities at all elevations) is likely the primary explanation for these shifts, although climate change is also an important factor for some. A clearer understanding of presettlement forest composition improves our ability to separate the relative importance of natural and human-driven influences on the species composition of today’s forests.

Fire exclusion effects on riparian forest dynamics in southwestern Oregon

Euro-American settlement and organized fire suppression have been associated with structural and compositional changes in many upland forests of the western United States, but little is known about the impacts on riparian forests, portions of the landscape protected for habitat and water quality. In this study, we used dendro-ecological methods to characterize the pre-settlement disturbance and tree recruitment processes of riparian forests in the Rogue River basin of southwestern Oregon and to identify changes to the forest structure and composition post-settlement. Our results suggest riparian forests in our study area developed with frequent disturbance by fire and that Euro-American land management shifted these forests onto a new successional trajectory. Our findings indicate the current hands-off management regime for riparian forests under the Northwest Forest Plan will continue along this altered trajectory and have ecologically undesirable consequences. We suggest that the restoration of pre-settlement forest dynamics in fire-prone forests of southwestern Oregon will be most effective where it includes density reductions in overstory trees and prescribed fire in both upland and riparian forests.

Forest Dynamics Across Three Century-Length Disturbance Regimes in the Illinois Ozark Hills

Forest community dynamics in the Illinois Ozark Hills was studied over a 300 y period that included three sequential disturbance regimes. Presettlement forest community patterns were reconstructed using witness tree data taken from the 1806–7 General Land Office survey records. Species, stem diameter and distance from the corner were obtained for a total sample of 958 witness trees on 479 section and quarter-section corners. Data were separated by site type based on 13 aspect and slope positions, but later were combined into six Ecological Land Type Phases (ELTPs) using cluster analysis and percent similarity. At the end of the presettlement and Disturbance Phase 1 (ca. 1810), Quercus and Carya species dominated forest communities (combined Importance Value, IV100 = 68–76) on the Southwest Slope, South Slope, Ridgetop and North Slope ELTPs. The combined IVs for all early successional species ranged from 74–81 while IVs of late successional fire-intolerant mesophytic species ranged from 19–26. Using mortality/damage data on mesophytic stems after prescribed fire and growth data on healthy stems, we estimated that the presettlement forest of mid to upper slopes and ridgetops developed under a fire return cycle of 30–45 y, a range that permitted a modest proportion of mesophytes to attain tree size. Forest communities on the cool moist Low Slope and Terrace ELTPs were dominated by mesophytic species, mostly Fagus grandifolia and Acer saccharum (combined IV100 = 50 and 63, respectively). We believe forest composition at the time of the land survey in 1806–7 primarily reflected the long-term effect of Early American burning during the 1600s and 1700s. The start of the Disturbance Regime 2, distinguished by the severe 1810–11 earthquakes that damaged thousands of hectares of forest, was followed by a period of settlement (ca. 1820–1930) characterized by a high level of fire, grazing and timber cutting. Based on early records, this level of disturbance was judged to be greater than that of presettlement time. The present forest was established in the mid to late 1800s and early 1900s of Regime 2. To provide continuity and reliability, tree, sapling and seedling data on the present forest were collected in all ELTPs from nested quadrats located at randomly selected, but continuously forested section and quarter-section corners from which witness tree data were previously recorded. In the presently mature forest overstory, Quercus and Carya had higher combined importance values on the Southwest Slope, South Slope and Ridgetop ELTPs (combined IV100 = 73–88) than presettlement communities on these ELTPs. On the North Slope ELTP, a sharp decrease in Quercus importance was partially offset by increases in Carya and Liriodendron tulipifera importance. On the Low Slope ELTP, there was an increase in the Quercus, Carya and L. tulipifera component from the presettlement forest to the present forest. The Terrace ELTP community was composed primarily of early successional lowland species in contrast to the forest of presettlement time. Disturbance Regime 3 of the last 75 y (ca. 1930–2005) was marked by near complete protection with the cessation of fire that accompanied the development of national and state forests, wilderness areas and wildlife refuges. This third period served as a reference to demonstrate the effect of absence of disturbance on the Quercus–Carya community. The absence of fire permitted major increases in mesophyte importance in the present understory (combined IV100 = 50–77) and stem growth into small tree stratum of nearly all Quercus–Carya dominated community types of all ELTPs. Based on a structure-for-time projection, related research analyses and an absence of disturbance that will permit continued growth of mesophytic species, the Illinois Ozark Hills may be the first contiguous forest region in central North America to completely convert from a Quercus–Carya to an Acer–Fagus dominated ecosystem.

Disturbance history and dynamics of an old-growth mixed species mountain forest in the Slovenian Alps

A long history of human presence in the Alps has made studies of natural forest structure, composition, and disturbance processes difficult. In the Slovenian Alps, we identified a mixed European beech ( Fagus sylvatica L.)-silver fir ( Abies alba Mill.)-Norway spruce ( Picea abies (L.) Karst.) stand with old-growth characteristics that escaped past cutting. We reconstructed the dynamics of the stand using a combination of stand and age structure analyses, dendroecological evidence of past canopy disturbance, and historical evidence of past human activities. The disturbance reconstruction revealed a stand-scale disturbance in the 1850s. Based on the presence of pit-and-mound topography throughout much of the stand and the absence of logging activities found in historical records, we assume this event was caused by strong winds. The current structure and composition of the stand are largely a result of this event. Post-disturbance forest development was dominated by the release of shade tolerant regeneration, especially F. sylvatica. The windthrow also created appropriate conditions (i.e. increased light and exposed mineral soil) for recruitment of less shade tolerant species, including larch ( Larix decidua Mill.) and maple ( Acer pseudoplatanus L.). The results suggest that periodic, intermediate severity wind disturbances, similar to the event documented here, may have had an important influence on pre-settlement forest dynamics in mixed mountain forests of the Alps, and add to the limited available information regarding the historic range of natural variability of disturbance processes. This information may be useful for forest management that attempts to emulate natural processes.

Forest disturbance frequency and patch structure from pre-European settlement to present in the Mixed Forest Province of Minnesota, USA

We used General Land Office survey data (1860–1890) and interpreted aerial photography from the 1930s, 1970s, and 1990s to quantify forest disturbance frequency and spatial patterns for four time periods in the Mixed Forest Province of Minnesota. The study region included eight subsections within the Mixed Forest Province of Minnesota’s Ecological Classification System. Presettlement disturbance and spatial pattern estimates varied across the eight subsections indicating a strong relationship to soil and landform characteristics. Land surveyors primarily recorded higher severity disturbances that resulted in significant tree mortality. The 1900–1940 era was characterized by a short-term increase in fire frequency that was relatively uniform across the study region, in contrast to the variability of the presettlement (1860–1890) landscape. In the postsettlement period (1940–1995), timber harvest replaced fire as the dominant disturbance factor. Similar management practices among subsections created similar harvest rates throughout the study region. These management practices imposed a more homogeneous pattern dominated by small (10–25 ha) patches. Management practices now have a greater influence than natural processes in the generation of landscape pattern in the Mixed Forest Province of Minnesota. Information on presettlement forest conditions and subsequent changes can be used by land managers to restore spatial pattern variability in managed forest landscapes.

Accounting for surveyor inconsistency and bias in estimation of tree density from presettlement land survey records

Presettlement land survey records provide baseline data on forest characteristics prior to major European settlement, but questions regarding surveyor bias and methodological consistency have limited confidence in quantitative analyses of this important data source. We propose new correction factors, calculated from bearings, distances, and species of bearing trees, to account for the effects of (i) inconsistency in quadrant configuration, (ii) bearing angle bias, and (iii) species bias on forest density and species composition estimated from presettlement land survey records. Computer simulations confirmed accuracy in random and nonuniform density forests, with moderate bias in very clustered and dispersed forests. A case study of township and quarter-section corners surveyed by the Holland Land Company in western New York demonstrates the potential magnitude of errors caused by surveyor inconsistency/bias in estimation of density and relative species frequency. The influence of nonuniform density, clustering, and dispersal on plotless density estimators remains an important obstacle to quantitative analysis of Presettlement land survey records. However, by accounting for uncertainties regarding surveyor methodology, the proposed correction factors add confidence to conclusions made regarding presettlement forest structure and composition.

Does forest structure affect reproduction of northern goshawks in ponderosa pine forests?

Summary Many management prescriptions are based on ecological hypotheses; evaluating empirical support for these hypotheses can improve management. There has been considerable dispute about the potential response of the northern goshawk to three management‐driven forest structures in ponderosa pine forests of the south‐western United States: (i) the structure recommended by US Forest Service's goshawk guidelines, designed to increase the abundance of 14 goshawk prey species and thus benefit goshawks; (ii) preferred foraging habitat as suggested by empirical evidence that goshawks forage selectively in areas with abundant large trees and dense canopy closure, rather than areas of highest prey abundance; and (iii) presettlement (i.e. prior to Euro‐American settlement) structure characterized by clumps of large trees, canopy closure < 40% and dense herbaceous understorey, which could have negative effects on goshawks. To evaluate empirical support for hypotheses that goshawk reproduction is affected by each of these three forest structures, we measured forest structure in a 1215‐ha nest‐centred circular area in each of 13 goshawk breeding areas on the Apache–Sitgreaves National Forest, Arizona. The breeding areas were selected to span the full range of productivity (fledglings per year monitored) over the previous 9‐year period. Forest structure had a moderate effect on goshawk productivity (r2 ≤ 0·46). Contrary to expectation, goshawk productivity decreased with increasing similarity to the goshawk guidelines. Goshawk reproduction was not correlated with resemblance of the breeding area to preferred foraging habitat or resemblance to presettlement forest conditions. Synthesis and applications. Because the goshawk guidelines may not improve goshawk reproduction, the Forest Service should reconsider its decision to apply the guidelines to most forested lands in Arizona and New Mexico. Managers should evaluate empirical support routinely for the major ecological hypotheses that underlie forest prescriptions.

Do coarse resolution U.S. presettlement land survey records adequately represent the spatial pattern of individual tree species?

Presettlement land survey records (PLSRs) are a valuable and unique source of information for the reconstruction of presettlement forest patterns. The purpose of this study was to determine whether coarsely resolved PLSRs are adequate to characterize the spatial patterns of individual tree species over large areas. The General Land Office Survey records of the PLSRs of Minnesota were used and species selected in the analysis were based on their abundances and degrees of clustering. A geostatistical procedure was developed to analyze observations of bearing-tree point-locations, at progressively coarser resolutions from 1×1 mile to 24×24 miles, to create spatially continuous probability surfaces of species occurrences across the landscape. Statistical and visual analyses of the geostatistical predictions indicated that coarsely resolved PLSRs, as coarse as 24×24 miles, can adequately represent the spatial pattern of individual species over large areas. Mean errors in predictions increased as more coarsely resolved data were used, primarily in response to the decreased abundance of a species and minorly in response to the degree of spatial clustering of a species. The results indicate that coarsely resolved township-level data of 6×6 miles can be used for presettlement vegetation reconstruction of large areas of several counties.

Genetic diversity and population structure of Quercus rubra (Fagaceae) in old-growth and secondary forests in southern New England

The genetic diversity and structure of Quercus rubra L. (Red Oak) in five secondary populations regenerated on old pastures and five paired old-growth populations were compared to determine whether secondary populations may have lost genetic diversity present in the presettlement forest. Old-growth samples had significantly greater nuclear allelic richness than secondary stands at the four microsatellite, simple sequence repeat (SSR), markers tested, but there was no significant difference at three chloroplast SSRs. There was however tenfold greater differentiation (high FST) among secondary forests than among old-growth forests for the chloroplast loci, suggesting greater population isolation at the time of their founding. The young age class in secondary stands had significantly greater chloroplast allelic richness than the old age class, suggesting some recovery as the forest cover increased. Forest cover and patch size at peak deforestation was not correlated with allelic richness in secondary stands, but the power of this test was low. The current size of old-growth stands is, however, positively correlated with levels of genetic diversity. Results suggest that deforestation for agriculture may reduce genetic diversity of forest trees, particularly in the first generation after deforestation, but that some recovery of this diversity is likely in these patchy landscapes. Wind dispersed pollen flow may increase in these areas, but animal dispersed seed flow may be reduced.

Presettlement forest in southern Ontario: Ecosystems measured through a cultural prism

To better manage southern Ontario's natural forests, the former and present status of old growth must be understood. We hypothesize that old-growth pine (Pinus spp.), although dominant elsewhere, was less common in southern Ontario than popular history suggests: we are obliged to evaluate historical information that has been filtered both by the original compilers and through our own biases. Beginning around 600 AD, the predominant beech (Fagus americana) forest was partially replaced by maple (primarily Acer saccharum), oaks (Quercus spp.) and eastern white pine (P. strobus). This pine increase either followed abandonment of pre-Columbian agriculture or, more plausibly, accompanied climate cooling. Eighteenth and 19th century European settlers encountered abundant large trees, which they hewed for square pine timber, milled timber, and tanbark. Other stands were cut and burned for agricultural clearance, with a potash by-product. Until recently, Ontario research emphasized the old-growth pine stands of central and northern Ontario to the relative exclusion of other kinds of old forest because very few southern Ontario old-growth stands remained to study. Ontario forest resource inventory data (FRI) show stands of over 150 years totalling only 1475 ha in 1978, concentrated on the Oak Ridges Moraine, the St. Lawrence Valley and the Awenda Peninsula. Red (P. resinosa) and eastern white pine stands constituted only 5.3% of the 1978 forested area, with virtually none of over 150 years, whereas eastern hemlock (Tsuga canadensis) stands constituted 12.8%. The difficulty in finding modern old growth necessitates historical reconstruction using physical, written and graphical resources, including early survey records and trade statistics. In a case study of 1822 survey data from Darling Township (Lanark Co.) and 1960 FRI, vegetation was classified using TWINSPAN and mapped using ARC/INFO Thiessen polygons. In 1822, dominant hemlock occupied half the township but it has since been eliminated as a dominant. Conversely, there were no pine-dominated forests in 1822, but these had increased to 16% of the area by 1960. A second case used similar methods, with 1855 data for St. Edmunds and Lindsay townships (Bruce Co.) and 1981 FRI. Although logging halved the area and reduced the stature of pines in the large pinery, the elimination of dominant hemlock (originally 41% by area) is more significant. Fragmentary square timber trade data suggest that at least half the large pines in Bruce County were in St. Edmunds, so pine must have been spectacularly concentrated in a few areas. The third case, a map constructed from Gourlay's 1817–1819 survey, also demonstrates that pine-dominated areas were in the minority in southern Ontario, concentrated on sandy soils around Lakes Ontario and Erie. However, big hemlocks, beeches, maples and oaks were much more common overall. Management responses to this information should include designation of older southern Ontario forest stands (especially those never cleared since settlement) for maturation into an old-growth state, and the systematic restoration of eastern hemlock and beech stands for conservation purposes in southern Ontario. Key words: old-growth forest, Canada, Ontario, historical ecology, forest history