Old-growth Forest Remnants Research Articles

Repeated insect outbreaks promote multi-cohort aspen mixedwood forests in northern Minnesota, USA

Characterizing the timing, severity, and agents of historic forest disturbances is critical to developing management and conservation strategies based on natural processes. Typically such information is derived from retrospective studies of remnant old-growth forests; however, this approach has limited application in regions dominated by secondary forests heavily influenced by past land-use. One striking example is the secondary aspen mixedwood forests of northern Minnesota, which have risen in both abundance and aerial extent, the result of post-settlement harvesting and subsequent land-use changes. Given their recent rise in abundance, as well as their dominance by relatively short-lived aspen, they have not been the focus of retrospective studies examining pre-settlement conditions. Using methods of dendrochronology, we reconstructed nearly a 90-year history of canopy disturbances and stand development for nine secondary mesic aspen mixedwood forests of northern Minnesota. Results show all stands initiating after near stand-replacing disturbance, presumably harvests, marked by initial recruitment dominated by Populus tremuloides. Ensuing development included an extended recruitment period by shade-tolerant species such as Abies balsamea, Acer rubrum, and Picea glauca. However, some stands experienced defoliation by forest tent caterpillar ( Malacosoma disstria) quite early during the stem exclusion stage (major events occurring as early as 23 years after stand initiation), causing tree mortality and giving rise to a new cohort. Subsequent repeated outbreaks of tent caterpillar and spruce budworm ( Choristoneura fumiferana) further opened the canopy, resulting in complex mixed-species, multi-cohort stands. This study is one of the first to link chronic defoliation events with long-term community dynamics for this forest type. Our findings highlight the critical roles these events play in structuring aspen mixedwood forests, particularly within the early stages of stand development, resulting in multi-cohort stands. Moreover, our findings support the growing body of literature suggesting that the range of variability in aspen age structures extends beyond the single-cohort model that has guided forest management in this region. Collectively, these findings have important implications for the design of forest management practices that approximate this range of variability and emulate defoliation disturbances, with early harvest entries aimed at increasing stand structural and compositional complexity.

Forest Biodiversity Assessment in Relic Ecosystem: Monitoring and Management Practice Implications

The remnants of old-growth cedar forests in Lebanon are currently protected since they are taken to represent relic ecosystems sheltering many endemic, rare and endangered species. However, it is not always obvious how “natural” these forest relics are, and how the past use, conservation and management history have affected their current structural properties and species community composition. Even though Integrated Monitoring Programs have been initiated and developed, they are not being implemented effectively. The present research studied the effect of forest stand structure and the impacts of the anthropogenic activities effects on forest composition and floristic richness in four cedar forests in Lebanon. Horizontal and vertical structure was assessed by relying on the measurement of the physical characteristics and status of cedar trees including diversity and similarity indices. Two hundred and seventeen flora species were identified, among which 51 species were found to have biogeographical specificity and peculiar traits. The species composition seems not to be correlated with stand age structure; however, the occurrence of multiple age cedar stands favors floristic richness and variability in species composition as observed in one of the stands where the variation in diversity indices was high. In conclusion; to conserve biodiversity across landscapes, it is necessary to maintain a collection of stands of different vertical structure; an effect produced both by natural and anthropogenic disturbances since they both create a mosaic of different aged succession stands.

Logging-Induced Edge and Configuration of Old-Growth Forest Remnants in the Eastern North American Boreal Forests

ABSTRACT: Worldwide, old-growth forest loss and fragmentation resulting from logging are considered major threats to biodiversity. In many regions of the boreal zone, remaining patches of old-growth forests left following logging are restricted to small areas exposed to edge effects. Our objectives were to evaluate, from a literature review, the distance of edge influence (DEI) induced by sharp logginginduced edges on adjacent old-growth residual forests and to compare, in order to exemplify edge effect influence, two contrasting scenarios of residual stand configurations (linear vs. agglomerated). Synthesis from studies conducted in boreal forests of Canada and Fennoscandia indicates a DEI of ∼50 meters for residual old-growth forests located along recently (≤ 20 years) cutover areas. Based on the comparison of two contrasted scenarios, we demonstrate the strong relationship between residual forest configuration and area under edge influence. For a similar area of residual old-growth forest, linear strip...

Forests Regenerating after Clear-Cutting Function as Habitat for Bryophyte and Lichen Species of Conservation Concern

The majority of managed forests in Fennoscandia are younger than 70 years old but yet little is known about their potential to host rare and threatened species. In this study, we examined red-listed bryophytes and lichens in 19 young stands originating from clear-cutting (30–70 years old) in the boreal region, finding 19 red-listed species (six bryophytes and 13 lichens). We used adjoining old stands, which most likely never had been clear-cut, as reference. The old stands contained significantly more species, but when taking the amount of biological legacies (i.e., remaining deciduous trees and dead wood) from the previous forest generation into account, bryophyte species number did not differ between old and young stands, and lichen number was even higher in young stands. No dispersal effect could be detected from the old to the young stands. The amount of wetlands in the surroundings was important for bryophytes, as was the area of old forest for both lichens and bryophytes. A cardinal position of young stands to the north of old stands was beneficial to red-listed bryophytes as well as lichens. We conclude that young forest plantations may function as habitat for red-listed species, but that this depends on presence of structures from the previous forest generation, and also on qualities in the surrounding landscape. Nevertheless, at repeated clear-cuttings, a successive decrease in species populations in young production stands is likely, due to increased fragmentation and reduced substrate amounts. Retention of dead wood and deciduous trees might be efficient conservation measures. Although priority needs to be given to preservation of remnant old-growth forests, we argue that young forests rich in biological legacies and located in landscapes with high amounts of old forests may have a conservation value.

Decline of Birds in a Human Modified Coastal Dune Forest Landscape in South Africa

Previous studies demonstrate that old-growth forest remnants and vegetation regenerating after anthropogenic disturbance provide habitat for birds in a human modified coastal dune forest landscape in northern KwaZulu-Natal, South Africa. However, occurrence does not ensure persistence. Based on a 13-year monitoring database we calculated population trends for 37 bird species and general trends in overall bird density in different vegetation types. We evaluated species' characteristics as covariates of population trend and assessed changes in rainfall and proportional area and survey coverage per vegetation type. 76% of species assessed have declined, 57% significantly so at an average rate of 13.9% per year. Overall, bird density has fallen at 12.2% per year across old-growth forest and woody regenerating vegetation types. Changes in proportional area and coverage per vegetation type may partly explain trends for a few species but are unlikely to account for most. Below average rainfall may have contributed to bird declines. However, other possibilities warrant further investigation. Species with larger range extents tended to decline more sharply than did others, and these species may be responding to environmental changes on a broader geographical scale. Our results cast doubt on the future persistence of birds in this human modified landscape. More research is needed to elucidate the mechanisms driving population decline in the study area and to investigate whether the declines identified here are more widespread across the region and perhaps the continent.

Topographic and compositional influences on disturbance patterns in a northern Maine old-growth landscape

Disturbance patterns are strongly coupled with forest composition and structure, and patterns change through time in response to shifts in climate, anthropogenic impacts and other factors. Knowledge of the natural disturbance patterns for establishing baseline conditions for a forest type or ecosystem facilitates change detection for other elements of the biophysical system important to management and conservation. Dendrochronological reconstructions from old-growth forest remnants throughout northeastern North America document average decadal rates of disturbance of 5%–<10% over the last 150–300 years. Relatively frequent, low severity disturbance characterized by small gaps representing canopy openings made by 1–3 trees prevail in these forests dominated by varying mixtures of late-successional tree species. Few studies, though, have explicitly characterized differences related to composition or topographic setting in old-growth landscapes. We addressed this by comparing the temporal and spatial disturbance patterns reconstructed from tree rings at two spatial resolutions (0.5 ha and 200 m 2). Sites were selected to assess the influence of topography (slope) and cover type in stands where red spruce ( Picea rubens Sarg) and balsam fir ( Abies balsamea L. Mill) were key components. Low rates of disturbance (average <10% per decade) and small gap sizes (≤30 m 2) prevailed in all stands during the decades from 1850–1980. Episodic pulses of disturbance, of nearly moderate intensity in some stands, opened ca. 20–30% of the canopy area and were associated with wind events and/or insect outbreaks that differentially affected stands. We found no significant difference in the average temporal rates of disturbance related to cover type or topography in 0.5-ha plots. However, the influence of these factors was evident in comparisons of gap areas estimated for 200-m 2 plot sections. At this resolution, the largest canopy openings (≥100 m 2) occurred most frequently in slope sites, enabling pulses of canopy accession for Betula alleghaniensis (Britton). Whereas the smallest canopy openings (≤30 m 2) dominated softwood stands, favoring red spruce, balsam fir and other shade-tolerant species throughout the forest. The variable effects of common disturbance agents, regardless of topographic position and/or cover types, points to the important role of biological legacies determining stand structure and composition on subsequent disturbance events and long-term patterns.

Canopy gaps in an old-growth fir-beech forest remnant of Western Carpathians

The old-growth forest remnants of Western Carpathians provide a unique possibility to study the disturbance regimes of forest ecosystems without human influence. This study investigated the gap dynamics in beech-dominated old-growth forest Badinsky prales in Central Slovakia. Considering the decline of silver fir in last decades, the study analyzed the main characteristics of disturbance regime with the emphasis on the role of fir. On a 5-ha research plot, the dominant tree species was beech, the proportion of fir reached about 10%. However, a significantly higher proportion of fir (>30%) was observed in the coarse woody debris. In total, 45 canopy openings were recorded. Canopy gaps and expanded gaps covered 11.3 and 37.9% of the forest area, respectively. Despite the highest frequency of small gaps <100 m2, their proportion of the overall gap area reached only 20%, what suggests the important role of intermediate and large gaps in the gap dynamics as well. The analysis of gapmakers’ crown projections confirmed a rather low contribution of fir (14.6%) to the gap formation despite its relatively intensive mortality. A high variability of the next generation age between the gaps (6–44 years) was recorded what suggests a large temporal variation of the disturbance events. The lateral expansion of adjacent trees was found to be the determining process for the closure of small canopy openings. The intermediate and large gaps are more likely closed by the height growth of natural regeneration and understory trees that are present on the majority of the area.

Old Forests and Endangered Woodpeckers: Old-Growth in the Southern Coastal Plain

Southern old-growth forests are small and rare, but critical in their support of biodiversity. While the remnant old-growth forests contain diversity that is significant regionally and globally, they most likely represent only a portion of the variety that old forests once sustained. High within-habitat diversity and rarity in the landscape magnify the conservation value of these systems. Old-growth stands of two particular communities—longleaf pine (Pinus palustris) forests and floodplain (bottomland/swamp) forests—have emblematic links to two notable bird species of concern, the Red-cockaded (Picoides borealis) and Ivory-billed (Campephilus principalis) Woodpeckers. In addition to conservation importance, southern old forests have social and economic values that are in danger of further impoverishment if these systems are lost to future generations. Summarizing the findings from a recenatus and values, identify current threats, and describe potential strategies to promote greater long-term conservation of old forests across the South.

Resilience of tropical rain forests: tree community reassembly in secondary forests

Understanding the recovery dynamics of ecosystems presents a major challenge in the human-impacted tropics. We tested whether secondary forests follow equilibrium or non-equilibrium dynamics by evaluating community reassembly over time, across different successional stages, and among multiple life stages. Based on long-term and static data from six 1-ha plots in NE Costa Rica, we show that secondary forests are undergoing reassembly of canopy tree and palm species composition through the successful recruitment of seedlings, saplings, and young trees of mature forest species. Such patterns were observed over time within sites and across successional stages. Floristic reassembly in secondary forests showed a clear convergence with mature forest community composition, supporting an equilibrium model. This resilience stems from three key factors co-occurring locally: high abundance of generalist species in the regional flora, high levels of seed dispersal, and local presence of old-growth forest remnants.

Assessing the extinction vulnerability of wood-inhabiting fungal species in fragmented northern Swedish boreal forests

Fragmentation of old-growth forests and greatly reduced amounts of coarse dead wood in managed forests threat the persistence of many saproxylic species in boreal Fennoscandia. Individual old-growth forest remnants may lose species over time as they pay off their extinction debt. We tested this by comparing the observed site occupancy of individual wood-inhabiting fungal species in isolated old-growth stands (i.e. woodland key habitats; WKHs) with statistical predictions of their occupancy assuming potential extinction debt had already been paid off. The occupancy of species was analysed in two sets of WKHs differing in time since isolation (i.e. recent and old isolates). Few species occurred more frequently than expected in WKHs. However, patterns across species and across all WKHs masked important differences among species in their risk of facing future extinction. The site occupancy decreased significantly between recent and old isolates for a group of annual, red-listed specialist fungal species, suggesting that an extinction debt in WKHs may exist among specific species confined to coarse dead wood and old-growth forest habitat. Generalist species that also occur in the surrounding matrix showed no negative trends, or actually increased in site occupancy, making future extinctions less likely. Thus, continuing loss of threatened species are likely if not preservation of WKHs are combined with other conservation efforts in managed forest landscapes. Natural forest landscapes may serve as important references when aiming to identify species in risk of future extinction but more detailed knowledge about the biology of the most vulnerable species is also required.

Long-term spatial dynamics of Acer saccharum during a population explosion in an old-growth remnant forest in Illinois

Species richness and evenness have greatly declined in oak–hickory forests in the central hardwood region in the U.S.A. in the past 100 years due to the rapid population growth of Acer saccharum. This study used a 50-year record of spatial dynamics to examine how demographic processes, particularly recruitment, may have contributed to this increase in an old-growth forest remnant, Brownfield Woods, Urbana, Illinois, U.S.A. The impact of canopy disturbance, including the outbreak of Dutch elm disease, on this increase was also evaluated. Historical maps of trees (≥7.6 cm DBH) from 1951, 1988, and 2001 in a 180 m × 280 m area were used to develop a series of univariate Ripley's L( d) functions to study changes in spatial patterns of three size classes of A. saccharum over time. Bivariate Ripley's L( d) functions were also utilized to evaluate spatial associations between recruitment and canopy disturbance. Our results indicated that A. saccharum was aggregated at most spatial scales up to 80 m during 1951–2001. Such aggregation arose mainly from small individuals. Furthermore, newly recruited individuals were aggregated at multiple spatial scales, and were significantly associated with canopy disturbance in general, as well as gaps created by Ulmus trees killed by Dutch elm disease. The aggregation of the 1951 initial group of small individuals changed via mortality to a random distribution over time. The results indicate that tree deaths caused by disturbances of different scales and types were the main cause of increased recruitment of A. saccharum in Brownfield Woods. The occurrence of Dutch elm disease further accelerated its population increase. This study demonstrated a direct spatial link between recruitment of A. saccharum and disturbance, and provided a long-term case study of a population explosion.

Impact of spatial heterogeneity of neighborhoods on long-term population dynamics of sugar maple ( Acer saccharum)

We evaluated the impact of spatial heterogeneity resulting from disturbance and neighbor density on long-term population dynamics of sugar maple ( Acer saccharum) in Brownfield Woods, an old-growth forest remnant in central Illinois. All trees with diameter at breast height (DBH) ≥ 7.6 cm in eight discrete quadrats (48 m × 68 m) and one large quadrat (216 m × 260 m) were mapped in Brownfield Woods in 1951, 1988, and 2001. Two sets of neighbor-specific transition matrices were constructed for two census periods (1951–1988 and 1988–2001) based upon historical maps of trees. Different neighborhoods defined by the occurrence of disturbance and neighbor density resulted in major differences in subsequent demography and population dynamics of A. saccharum in Brownfield Woods during 1951–2001. Disturbance subpopulations with high neighbor density demonstrated greater population growth than the other subpopulations and were characterized by relatively high recruitment and mortality. Dutch elm disease subpopulation shared similar characteristics. In contrast, non-disturbance subpopulations demonstrated census-specific demography. Using matrix modeling, we demonstrated the importance of spatial heterogeneity at the scale of neighboring trees to the dynamics at the scale of tree populations.

Spatial Distribution of Riparian Zone Coarse Woody Debris in a Managed Northern Temperate Watershed

ABSTRACT Coarse woody debris is an important structural component of both terrestrial and aquatic ecosystems. We investigated coarse woody debris size-structure, decay class composition and distribution within the interface between second growth mixed conifer-hardwood forests and perennial streams in a catchment of the Lake Superior watershed on the Keweenaw Peninsula, Michigan. Down dead wood accumulation was nonlinearly distributed along transects perpendicular to streams and reached a peak between 30 and 50 m away from the wetted stream channels. Variability in the abundance of standing snags displayed a significant increase with distance. The coarse wood accumulations we observed were consistent with levels reported for upland, second-growth forests and were low compared to old-growth forest remnants in the region. Large (>40 cm diam) down dead wood will probably be the slowest pool to recover from logging and land clearing activities that occurred in the watershed prior to the turn of the 19th Centur...

The role of isolated old oak trees in maintaining beetle diversity within larch plantations in the central mountainous region of Japan

Old oak trees ( Quercus crispula Blume) that are remnants of former old-growth forests have been isolated singly or as small patches within a matrix of conifer plantations in the central mountainous region of Japan. Fifty-six aerial Malaise traps were deployed around seven isolated oak trees within larch [ Larix kaempferi (Lamb.) Carrière] plantations and at seven larch plots within larch plantations. The species richness and composition of beetles (Cerambycidae, Curculionidae, Elateridae, Chrysomelidae, and Lycidae) around the oak trees were compared to those in the larch plantations. Species richness was higher around the oak trees than in the larch plantations, and the species composition differed. A number of saproxylic beetles were characteristic of isolated old oak trees. These results emphasize the importance of isolated old oak trees for maintaining beetle diversity in larch plantations and raise the possibility that further losses of these isolated oak trees could eliminate many individuals and reduce beetle diversity in larch plantations.

USING A GENERALIZED VEGETATION MODEL TO SIMULATE VEGETATION DYNAMICS IN NORTHEASTERN USA

Models based on generalized plant physiological theory represent a promising approach for describing vegetation responses to environmental drivers on large scales but must be tested for their ability to reproduce features of real vegetation. We tested the capability of a generalized vegetation model (LPJ-GUESS) to simulate vegetation structural and compositional dynamics under various disturbance regimes at the transition between prairie, northern hardwoods, and boreal forest in the Great Lakes region of the United States. LPJ-GUESS combines detailed representations of population dynamics as commonly used in forest gap models with the same mechanistic representations of plant physiological processes as adopted by a dynamic global vegetation model (the Lund-Potsdam-Jena [LPJ] model), which has been validated from the stand to the global scale. The model does not require site-specific calibration. The required input data are information on climate, atmospheric CO2 concentration, and soil texture class, as well as information on generally recognized species traits (broad-leaved vs. needle-leaved, general climatic range, two fire-resistance classes, shade-tolerance class, and maximum longevity). Model predictions correspond closely to observed patterns of vegetation dynamics and standing biomass at an old-growth eastern hemlock (Tsuga canadensis)/hardwood forest (Sylvania Wilderness, Michigan), an old-growth forest remnant from the “Great Lakes Pines Forest” (Itasca State Park, Minnesota), and a presettlement savanna (Cedar Creek Natural History Area, Minnesota). At all three sites, disturbance (wind or fire) strongly controls species composition and stand biomass. The model could be used to simulate vegetation dynamics on a regional basis or under past or future climates and atmospheric CO2 levels, without a need for reparameterization.

Patterns of Ectomycorrhizal-Fungi Consumption by Small Mammals in Remnant Old-Growth Forests of the Sierra Nevada

Patterns of Ectomycorrhizal-Fungi Consumption by Small Mammals in Remnant Old-Growth Forests of the Sierra Nevada

Regional Distribution and Dynamics of Coarse Woody Debris in Midwestern Old-Growth Forests

Abstract Old-growth forests have been noted for containing significant quantities of deadwood. However, there has been no coordinated effort to quantify the deadwood component of old-growth remnants across large regions of temperate deciduous forest. We present results of a regional inventory that quantifies and examines regional and temporal trends for deadwood in upland old-growth forest remnants within Indiana, Illinois, Missouri, and Iowa. From 1992 to 1994, down wood ≥ 10 cm in diameter and standing trees ≥ 10 cm dbh were inventoried on 328 one-tenth ha plots at 12 sites. The mean ratio among the sites by diameter class of the number of standing dead to standing live trees (dead/live ratio) ranged from 0.08 to 0.11 and was consistent for trees ≤ 65 cm in diameter. The dead/live tree ratio was generally greater for old-growth than for mature second-growth forests (70 to 90 yr old). Mean volume of standing dead trees across all old-growth sites was 21.4 m³/ha and down wood was 60.4 m³/ha. However, both standing and down wood volume (total deadwood) increased along a regional gradient of increasing productivity from southwest Missouri to northeast Indiana and also increased with increasing age of dominant and codominant trees. Old-growth forests on high productivity sites averaged more pieces/ha of down wood in all diameter classes and higher volume/ha of down wood in nearly all diameter classes than did old-growth forests on low productivity sites. A chronosequence of forests from 10 yr to more than 200 yr since stand establishment indicated a sharply declining down wood volume from age 10 to 70 yr followed by increasing volume between 80 and 200 yr. For. Sci. 45(2):302-313.

Habitat qualities versus long-term continuity as determinants of biodiversity in boreal old-growth swamp forests

Natural swamp forests are extremely rare in Sweden because of extensive drainage and logging activities. This study reports a total of 517 species (148 vascular plants, 131 mosses, 64 hepatics, 142 lichens and 32 wood-inhabiting fungi) from 10 small remnants of boreal old-growth swamp forests. The 195 bryophytes found represent 33% of the total number of bryophyte species in the Swedish boreal flora. As the average area of the forests was only 2ha, this figure clearly illustrates the important role of the swamp forests as centres of bryophyte biodiversity.There was no relationship between the occurrence of 33 lichen and fungi species considered to indicate natural forests with long stand continuity and the known long-term continuity of the forests. The forests most affected by earlier natural and man-made fires harboured more of these species than forests less affected by fire disturbance. The most important variable explaining biodiversity as well as presence of ‘continuity indicator species’ was the amount of dead wood present. A more critical and careful use of the concept of forest continuity is needed.

Structure and Composition of Goll Woods, an Old-Growth Forest Remnant in Northwestern Ohio

BOERNER, R. E. J. AND Do-SOON CHO (Dept. Bot., Ohio State Univ., 1735 Neil Ave., Columbus, OH 43210). Structure and composition of Goll Woods, an old-growth forest remnant in northwestern Ohio. Bull. Torrey Bot. Club 114:173-179. 1987.-Species composition, sizefrequency distributions, and environment-vegetation relationships were studied in Goll Woods, the last known uncut remnant of the Black Swamp forest of northwestern Ohio. Relatively well-drained fossil beach ridges were dominated by sugar maple (Acer saccharum) and beech (Fagus grandifolia), with sycamore (Platanus occidentalis) and white oak (Quercus alba) also common; poorly drained flats were occupied by silver maple (A. saccharinum), American elm (Ulmus americana), bur oak (Q. macrocarpa), and ashes (Fraxinus spp.). Transitional sites had higher abundances of basswood (Tilia americana), ironwood (Carpinus caroliniana), red oak (Q. borealis), and red maple (A. rubrum). Regressions of axis scores from Detrended Correspondence Analysis indicated relationships among species composition and soil texture. Bur oak, white oak, sycamore, chinquapin oak (Q. muehlenbergii), and cottonwood (Populus deltoides) had emergent individuals over 1 m dbh but lacked stems 300 yr ago.

Composition and Structure of an Old-Growth Forest Remnant in Unglaciated Southwestern Illinois

All stems 2.6 inches (6.6 cm), or greater, in diam breast height (dbh) were tallied in an 18-acre (7.2 ha) forest on loessal soils of the Ozark Hills in Union Co., Ill. Understory and ground vegetation were sampled in 0.01and 0.001-acre (4 sq m) transects and quadrats. Stand density was 221 stems per acre and basal area was 130 sq ft. Sugar maple (Acer saccharum) was the leading species based on importance values of 38 species. The canopy strata included shagbark hickory (Carya ovata), black oak (Quercus velutina), northern red oak (Q. rubra), sugar maple and white oak (Q. alba). Sugar maple and shagbark hickory increased substantially in the canopy during an 11-year period from 1956 to 1967, while northern red oak and black oak decreased in importance value. The increased importance of sugar maple in the stand was attributed to absence of major disturbance, climatic and soil changes in the past century, related to increased precipitation during much of the period, and selective cutting. The stand was classified as western mesophytic (Braun, 1950).