Evaluation of the effects of ozone and acidic precipitation,alone and in combination,on the photosynthesis,nutrition, and growth of red spruce and sugar maple

Substantial and widespread morbidity and mortality of red spruce have been observed in high elevation forests of the northeast under circumstances indicative of a stress-related disease. Whether red spruce at lower elevations are experiencing a more subtle loss of growth and vigor is uncertain. In addition, sugar maple has exhibited decline of varying extent and intensity for several decades. Forests in the northeast are exposed to two air pollutants, ozone (O₃) and acidic precipitation, that are widespread in occurrence and have the potential, both individually and collectively, to produce impacts to forest trees. the roles, if any, of these two stress agents in the tree declines found in the northeast are not known.In 1986, a five-year study was initiated to evaluate the effects of O₃ and acidic precipitation on red spruce and sugar maple. The trees will be exposed to controlled levels of O₃ and acidic precipitation in the field using open-top chambers. The experiment is a 4×3 factorial conducted in split plots with O₃ treatments as whole plots and simulated rain treatments comprising the split plots. Broadly stated, the research will evaluate the effects of the pollutants on the processes, fluxes, and pools associated with carbon, water, and nutrients in the soil/tree/atmosphere system. These evaluations will be conducted on a systems level and will be integrated through the development of mechanistic simulation models.Assessment of the effects of the treatments on carbon fixation by photosynthesis, the loss of carbon through respiration, and the allocation of carbon in growth will be a central focus of the study. Whole-tree cuvettes will be used to assess net photosynthesis, respiration, transpiration, and stomatal conductance.Considerable emphasis will be placed on determining the influences of the treatments on the biogeochemistry of the system. These studies will focus on the leaching of nutrients from the tree canopy, the mobilization and loss of nutrients from the soil, soil solution chemistry, and the alteration of tree nutrition by the input of additional nitrogen in precipitation.Statistical and simulation modeling will be used to assess and describe the effects of the treatments. The modeling approaches are different in technique, but complementary. Statistical models will be used to describe the responses of growth and physiological variables to the ozone and acidic precipitation treatments. Simulation models will be built to describe the relationships between photosynthesis, respiration, nutrition, and water use, how these processes are affected by the treatments, and how these effects ultimately result in altered growth. The simulation models will initially provide a framework for the formulation of hypotheses regarding the interrelationships of plant components and processes and how they are affected by the treatments.Contribution from Fourth World Wilderness Congress—Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Air pollution and forestry in czechoslovakia

One third of the territory of Czechoslovakia is covered by forests. A substantial part of them is damaged in various degrees by air pollution. The air pollution influence on forests developed to a very serious problem during the last 40 years. The main pollutant at present is SO₂ acting directly, but the improtance of soil changes due to acid deposition increases. The consequences are increased mortality and decreased increment in the forests, further consequences are the loss of valuable ecotypes, impact on water management and decreased stability of the landscape. There are limited possibilities of the forest sector to reduce the consequences.Contribution from Fourth World Wilderness Congress—Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Spatial patterns in forest composition and standing dead red spruce in montane forests of the Adirondacks and northern Appalachians

The decline of red spruce (Picea rubens Sarg.) in montane forests of the northeastern United States has been previously reported. The objective of this study was to assess spatial patterns, if any, in standing dead red spruce stems in the Adirondacks of New York and northern Appalachians of Vermont, New Hampshire, and Maine. A stratified random sample of 19 mountains along a west to east transect in the Adirondacks and the northern Appalachians showed that the live basal area of all species was highest in the White Mountains (34.6 m² ha^–1) and lowest in the Adirondack Mountains (23.7 m² ha^–1) in the Green Mountains was significantly lower than in any other region. Intact standing dead red spruce in the Adirondack and Green Mountains (30%) was significantly higher than that in the three eastern clusters (14%). The amount of intact standing dead red spruce trees increased with elevation in only the western part of the region. With the exception of the Adirondacks, there was a greater average percent dead red spruce on the west side than on the east side of each mountain. The sum of standing dead for other tree species (average 13%) showed no statistically significant patterns with region, elevation or aspect, and was significantly lower than the amount of total dead red spruce (average 42%). The standing dead red spruce patterns we observed cannot be associated with any specific causal factors at this time.     

Air pollution and forest decline near Mexico City

The forests of Abies religiosa Schl. et Cham. in the north and the northeast slopes of the mountains of the southwestern region of the Valley of Mexico are in an acute process of decline, particularly the fir forest of the Cultural and Recreational Park Desierto de los Leones. The mortality of the trees began in 1981, and by 1987 30% of the trees of the Park had died; the mortality continues. The surviving trees are in a very poor crown condition, having thin crowns with many dead branches. in the light of current knowledge air pollution, in particular the oxidant gases (ozone), are the primary cause of decline, but other conditions or agents (age of the trees and diseases) could be contributing factors in the dying of the trees.Contribution from Fourth World Wilderness Congress-Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Monitoring the condition of the Canadian forest environment: The relevance of the concept of ‘ecological indicators’

The Canadian forest environment is characterized by high spatial and temporal variability, especially in the west. Our forests vary according to climate, landform, and surficial geology, and according to the type, intensity, extent of, and the time since the last disturbance. Most Canadian forests have had a history of repeated acute, episodic disturbance from fire, insects, wind, diseases and/or logging, with a frequency of disturbance varying from a few decades to many centuries. These sources of variability have resulted in a complex and continually changing mosaic of forest conditions and stages of successional development.Monitoring the quality of this dynamic forested landscape mosaic is extremely difficult, and in most cases the concept of a relatively simple index of forest ecosystem quality or condition (i.e. an ecological indicator) is probably inappropriate. Such ecological indicators are better suited for monitoring chronic anthropogenically induced disturbances that are continuous in their effect (e.g. acid rain, heavy metal pollution, air pollution, and the greenhouse effect) in ecosystems that, in the absence of such chronic disturbance, exhibit very slow directional change (e.g. lakes, higher order streams and rivers). Monitoring the effects of a chronic anthropogenic disturbance to forest ecosystems to determine if it is resulting in a sustained, directional alteration of environmental quality will require a definition of the expected pattern of episodic disturbance and recovery therefrom (i.e. patterns of secondary succession in the absence of the chronic disturbance). Only when we have such a temporal fingerprint of forest ecosystem condition for normal patterns of disturbance and recovery can we determine if the ecosystem condition is being degraded by chronic human-induced alteration of the environment. Thus, degradation is assessed in terms of deviations from the expected temporal pattern of conditions rather than in terms of an instantaneous assessment of any particular condition. The concept of ecological rotation (the time for a given ecosystem to recover from a given disturbance back to some defined successional condition) is useful in the definition of these temporal fingerprints. This requires information on the intensity of disturbance, the frequency of disturbance, and the rate of successional recovery. Only when all three of these are known or estimated can statements be made as to whether the ecosystem is in a longterm sustainable condition or not.The somewhat overwhelming complexity of this task has led forest ecologists to use ecosystem-level computer simulation models. Appropriately structured and calibrated models of this type can provide predictions of the overall temporal patterns of ecosystem structure and functions that can be expected to accompany a given frequency and character of episodic disturbance. Such models can also be used to examine the long-term consequences of chronic disturbances such as acid rain and climatic change. Predictive ecosystem-level models should be used in conjunction with some method of stratifying the inherent spatial biophysical variability of the forest environment, such as the biogeoclimatic classification system of British Columbia.     

The Impact of Landsat Satellite Monitoring on Conservation Biology

Landsat 7s recent malfunctioning will result in significant gaps in long-term satellite monitoring of Earth, affecting not only the research of the Earth science community but also conservation users of these data. To determine whether or how important Landsat monitoring is for conservation and natural resource management, we reviewed the Landsat programs history with special emphasis on the development of user groups. We also conducted a bibliographic search to determine the extent to which conservation research has been based on Landsat data. Conservation biologists were not an early user group of Landsat data because a) biologists lacked technical capacity – computers and software – to analyze these data; b) Landsats 1980s commercialization rendered images too costly for biologists budgets; and c) the broad-scale disciplines of conservation biology and landscape ecology did not develop until the mid-to-late 1980s. All these conditions had changed by the 1990s and Landsat imagery became an important tool for conservation biology. Satellite monitoring and Landsat continuity are mandated by the Land Remote Sensing Act of 1992. This legislation leaves open commercial options. However, past experiments with commercial operations were neither viable nor economical, and severely reduced the quality of monitoring, archiving and data access for academia and the public. Future satellite monitoring programs are essential for conservation and natural resource management, must provide continuity with Landsat, and should be government operated.     

A Screening Procedure for Identifying Acid-Sensitive Lakes from Catchment Characteristics

Monitoring of Wilderness lakes for potential acidification requires information on lake sensitivity to acidification. Catchment properties can be used to estimate the acid neutralizing capacity (ANC) of lakes. Conceptual and general linear models were developed to predict the ANC of lakes in high-elevation (2170 m) Wilderness Areas in Californias Sierra Nevada mountains. Catchment-to-lake area ratio, lake perimeter-to-area ratio, bedrock lithology, vegetation cover, and lake headwater location are significant variables explaining ANC. The general linear models were validated against independently collected water chemistry data and were used as part of a first stage screen to identify Wilderness lakes with low ANC. Expanded monitoring of atmospheric deposition is essential for improving the predictability of lake ANC.     

Mega-Development Trends in the Amazon: Implications for Global Change

This paper describes four global-change phenomena that are having major impacts on Amazonian forests. The first is accelerating deforestation and logging. Despite recent government initiatives to slow forest loss, deforestation rates in Brazilian Amazonia have increased from 1.1 million ha yr^–1 in the early 1990s, to nearly 1.5 million ha yr^–1 from 1992–1994, and to more than 1.9 million ha yr^–1 from 1995–1998. Deforestation is also occurring rapidly in some other parts of the Amazon Basin, such as in Bolivia and Ecuador, while industrialized logging is increasing dramatically in the Guianas and central Amazonia.The second phenomenon is that patterns of forest loss and fragmentation are rapidly changing. In recent decades, large-scale deforestation has mainly occurred in the southern and eastern portions of the Amazon — in the Brazilian states of Pará, Maranho, Rondônia, Acre, and Mato Grosso, and in northern Bolivia. While rates of forest loss remain very high in these areas, the development of major new highways is providing direct conduits into the heart of the Amazon. If future trends follow past patterns, land-hungry settlers and loggers may largely bisect the forests of the Amazon Basin.The third phenomenon is that climatic variability is interacting with human land uses, creating additional impacts on forest ecosystems. The 1997/98 El Niño drought, for example, led to a major increase in forest burning, with wildfires raging out of control in the northern Amazonian state of Roraima and other locations. Logging operations, which create labyrinths of roads and tracks in forsts, are increasing fuel loads, desiccation and ignition sources in forest interiors. Forest fragmentation also increases fire susceptibility by creating dry, fire-prone forest edges.Finally, recent evidence suggests that intact Amazonian forests are a globally significant carbon sink, quite possibly caused by higher forest growth rates in response to increasing atmospheric CO₂ fertilization. Evidence for a carbon sink comes from long-term forest mensuration plots, from whole-forest studies of carbon flux and from investigations of atmospheric CO₂ and oxygen isotopes. Unfortunately, intact Amazonian forests are rapidly diminishing. Hence, not only is the destruction of these forests a major source of greenhouse gases, but it is reducing their intrinsic capacity to help buffer the rapid anthropogenic rise in CO₂.     

Background Levels of Metals in Soils, McMurdo Station, Antarctica

McMurdo Station is the largest research station in Antarctica, with a population that ranges each year from 250 to 1200 people. Because of its size and 40-year history of use, a number of locations around the station have become contaminated with wastes. Soils and sediments in these areas have been shown to contain elevated levels of petroleum-related products, PCBs, other organics, and metals. While some remedial investigations have been conducted, background levels of metals in soils have not been determined. This paper reports on background levels of metals in a natural basalt-derived soil (gray soil) and scoria (soft porous rock used as fill, red soil) near McMurdo Station using two fundamentally different analytical procedures, concentrated acid extraction/analysis and total metals. These data facilitate determining the extent and levels of metal contamination near McMurdo Station and provide reference levels of metals for comparison with existing and future remediation data. There were statistically significant differences between metals concentrations in both gray and red soils, and no correlations between the level of extracted versus total metal. Generally, only a small fraction of a metal was extractable.     

Mineral Soil and Solution Responses to Experimental N and S Enrichment at the Bear Brook Watershed in Maine (BBWM)

Buried mineral soil-bags and natural solutions were studied as indicators of forest ecosystem response to elevated N and S inputs at the Bear Brook Watershed in Maine (BBWM). The BBWM is the site of a paired watershed manipulation experiment in a northern New England forested ecosystem. The study includes two small (10 ha each) catchments dominated by northern hardwood forests with red spruce in the upper elevations. Treatments consist of (NH4)2SO4 applied to the West Bear watershed six times per year, increasing N and S deposition 3× and 2× above ambient values, respectively. Buried mineral soil-bag changes over time reflected both the native soil environment and the treatments. Most of the treatment effects on mineral soils were evident as higher inorganic S found in the treated watershed soils. Adsorbed SO4 in the buried mineral soil-bags increased by approximately 40% under softwood stands and 50% under hardwood stands over the study period. Hardwood soil solutions responded with significant increases in NO3 and SO4 concentrations that resulted in accelerated cation leaching, primarily Ca and Al. Few differences that could be attributed to treatments were evident in soil solutions under softwoods. No treatment effects were evident in throughfall and stemflow chemistry.     

Global monitoring at the United States baseline stations with emphasis on precipitation chemistry measurements

The National Oceanic and Atmospheric Administration Geophysical Monitoring for Climatic Change program has operated four remote precipitation chemistry stations at two polar and two tropical Pacific locations for over a decade. Station geography and meteorology is discussed and a summary of the hydrogen, sulfate, and nitrate ion data collected since 1980 is presented. Results show that at all four locations, the ions which have major anthropogenic sources were far less concentrated than in samples collected in heavily industrialized areas in the northeastern United States and Europe. Concentrations at American Samoa and the South Pole showed little variability over the year whereas concentrations at Point Barrow, Alaska and Mauna Loa, Hawaii were highly variable.Contribution from Fourth World Wilderness Congress-Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Monitoring the health of a forest: A Canadian approach

In Canada, acid rain is the generic term encompassing all forms of air pollution — wet and dry deposition, gaseous pollutant concentrations, and airborne particulates. It was because these pollutants, alone or in combination, may directly or indirectly affect the heath of Canada's forests, that in 1984, the Canadian Forestry Service initiated a national forest monitoring program (Acid Rain National Early Warning System or ARNEWS).Research studies on pollutant effects of the past 15–20 years have demonstrated that it is not possible to define specific symptoms of acid rain or mixtures of pollutants on native tree species or specific responses of the forest ecosystem. Consequently, ARNEWS monitored incipient acid rain effects by determining the forest's state of health rather than by concentrating on specific pollutant responses.The detection system entails experienced insect and disease survey forest rangers assessing both specific plots and the forest as a whole for extraordinary forest damage. The techniques used include mensurational and symptomatological measurements as well as evaluation of stands for damage from natural and anthropogenic causes. Critical also to the system was the capability of the Canadian Forestry Service to support the detection system with research staff who could carry out studies to explain any abnormalities in forest condition detected during the annual surveys. The ultimate outcome of the monitoring system if unexplained forest damage is detected is a research project on possible causes.Contribution from Fourth World Wilderness Congress — Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Monitoring the results of Canada/U.S.A acid rain control programs: some lake responses

Aquatic acidification by deposition of airborne pollutants emerged as an environmental issue in southeastern Canada during the 1970s. Drawing information from the extensive research and monitoring programs, a sequence of issue assessments demonstrated the necessity of reducing the anthropogenic emissions of acidifying pollutants, particularly sulphur dioxide (SO₂). The 1991 Canada-U.S. Air Quality Agreement (AQA) was negotiated to reduce North American SO₂ emissions by 40% relative to 1980 levels by 2010, and at present, both countries have reduced emissions beyond their AQA commitment. In response to reduced SO₂ emissions, atmospheric deposition of sulphate (SO₄ ^2–) and SO₄ ^2– concentrations in many lakes have declined, particularly in south-central Ontario and southern Québec. Sulphate deposition still exceeds aquatic critical loads throughout southeastern Canada however. Increasing pH or alkalinity (commonly deemed recovery) has been observed in only some lakes. Several biogeochemical factors have intervened to modify the lake chemistry response to reduced SO₄ ^2– input, notably release of stored SO₄ ^2– from wetlands following periods of drought and reduction in the export of base cations from terrestrial soils. Three examples from Ontario are presented to illustrate these responses. Significant increases in pH and alkalinity have been observed in many lakes in the Sudbury area of Ontario due to the large reductions in local SO₂ emissions; early-stage biological recovery is evident in these lakes. An integrated assessment model predicts that AQA emission reductions will not be sufficient to promote widespread chemical or biological recovery of Canadian lakes. Monitoring and modeling are mutually supporting assessment activities and both must continue.     

Comparative Studies on the Usefulness of Seven Ecological Indices for the Marine Coastal Monitoring Close to the Shore on the Swedish East Coast

The simultaneous behaviour of seven ecological indices(Hurlberts, Margalefs, Menhinicks, Shannons,species number, Jaccards and saprobic index) wasstudied based on phytoplankton data close to the shoreon the East coast of Sweden during the summer 1998.The sampling stations had a similar eutrophicationlevel and were located in bays. Standard phytoplanktondatabases were used in calculating the indices, whichwere later compared using cluster analysis.Hurlberts, Margalefs, Menhinicks, Shannons andspecies number indices, as measure of communitydiversity, produced similar trends which oftendiffered from those based on Jaccards index ofsimilarity. However, the simultaneous use of theseindices was found meaningful as a possible part of themonitoring close to the shore. The application of asaprobic index lead to erroneous conclusions in thestudied case.     

Monitoring the biotic aspects of our environment as a policy instrument

As all environmental programs also programs monitoring the biotic aspects of our environment (dealt with in this article) should contribute to a more effective and efficient environmental policy. These programs have to function therefore (as no other type of environmental information does, according to the authors) as cheap and efficient early warning and early control systems, providing decision makers with important and reliable monitoring results.How these monitoring programs should function in the decision making process is illustrated in abstract in this article by a simple control system with feedback (as shown in Figures 1, 2 and 3).The monitoring programs dealt with in this article should enable us to detect and forecast changes in the most important biotic aspects of our environment and-by continuous monitoring-to control whether the use of policy instruments has been effective or not in averting or diminishing unwanted changes (problems).Two options of decision makers with respect to monitoring results are shown (either to disregard unwanted changes as a problem or to accept these changes as a problem and to do something about them). To contribute to an effective and efficient environmental policy monitoring results therefore have to be important and reliable enough to react upon.The question is raised which biotic aspects in our environment are (or have to be considered as) important (because of their own value, as indicators and/or as biotic conditions) and how reliable monitoring results can (have to) be obtained.It is discussed how environmentalists could try to make it more difficult for decision makers to duck the problems (by monitoring only important aspects and by using only perfectly clear targets and standards) and how they could try at the same time to make it easier for them to take action (by setting up integrated environmental monitoring programs in order to find out how desired and undesired changes can be influenced). The role of active publicity is stressed in this connection.     

MAPPING TROPICAL DEFORESTATION IN CENTRAL AFRICA

The NASA Landsat Pathfinder Humid Tropical Deforestation Project was to map deforestation activities in the humid tropics using datasets from both the Landsat TM (Thematic Mapper) and MSS (Multispectral Scanner System). In Central Africa, its effort had been constrained by the availability of cloud-free satellite coverage, especially for the 1970s Landsat MSS imagery. Here, we reported the deforestation rate and its spatial variability in the region using 18 pairs of co-registered Landsat TM imagery from the 1980s to 1990s. Of the total classified area of 416000 km, there were approximately 217000 km² of dense forest and 24000 km² of degraded forest in the 1980s. A total of 1012 km² of forest, including 542 km² of dense forest and 470 km² of degraded forest, were cleared annually with an annual deforestation rate of 0.42%, varying among scenes ranging from 0.03 to 2.72%. Additionally, an average of 0.12% (ranging from 0.01 to 0.77% among scenes) or 257 km² of dense forest was degraded annually. Regression analyses indicated that extensive deforestation occurred in areas with larger forest cover, including dense and degraded forests. Image interpretation also confirmed the hypothesized relationship between deforestation and forest accessibility. The annual clearance of the dense forest was significantly related to the rural population density, and there was a positive relationship between the dense forest degraded during the 1980s–1990s and the degraded forest area in the 1980s.     

Resource Use Rates and Efficiency as Indicators of Regional Sustainability: an Examination of Five Countries

We examine trends from 1970 to the mid 1990's of some variables related to development and sustainability for Costa Rica, Korea, Mexico, the Netherlands and the United States: first, by calculating energy and agricultural efficiencies over time, second, by examining the environmental impacts of economic activities, and third, by estimating ecological footprints. We find that many "optimistic" arguments about sustainability have been misleading, and that there is little or no indication that we are becoming any more sustainable or even efficient. Total quality-corrected energy consumption has increased for all five countries and the renewable energy portion is decreasing. The efficiency of turning energy into both agricultural production and GDP has declined for all countries except for the US. In general, there is a remarkable linearity between resource use and economic and agricultural production over all countries and all years, suggesting severe biophysical constraints to sustainable objectives. On the other hand, per capita ecological footprints have decreased somewhat in Costa Rica, Mexico, and the United States, while national ecological footprints have tended to remain constant except for Korea. While there has been a reduction of specific pollutants in the United States, some of this has been achieved by exporting heavy manufacturing industries. We conclude that continued population and economic growth in each country is likely to make the achievement of any kind of sustainability increasingly unlikely. Sustainability, if that is desirable, requires a very different approach than what we have undertaken to date.     

Using slides to test for changes in crown defoliation assessment methods part II: Application of the image analysis system CROCO

We tested whether the semi-automatic program CROCO can replace visual assessments of slides to detect changes in defoliation assessment methods. We randomly selected a series of slides of 24 Norway spruce trees with 220 field assessments made between 1986 and 1995. The slides had been randomly arranged and assessed by three experts without knowledge of the tree number or the year when the slide was taken. Defoliation scores were computed with CROCO. Each tree had thus three different defoliation scores, field assessments, photo assessments and CROCO scores.CROCO scores were less correlated with the field assessments (Spearmans rank correlation: 0.67) than were the slide assessments with the field assessments (0.79–0.83). However, CROCO was not biased against the field scores, while slide assessments systematically underestimated defoliation.In a multi-variate mixed effect model none of the variables tree overlap, tree visibility and light conditions was significant in explaining differences between slide assessors and CROCO scores. The same model applied for the differences from the field scores yielded significant effects for poor light conditions (CROCO and all assessors), for crown overlap (CROCO and one assessor) and for visibility (one assessor). We conclude, therefore, that CROCO can be used to detect past and future changes in assessment methods without bias if poor quality photographs are avoided.     

Beyond the Guidelines: Practical lessons for monitoring

A series of workshops have provided extensive feedback on a recently published manual, Monitoring Guidelines to Evaluate Effects of Forestry Activities on Streams in the Pacific Northwest and Alaska (Guidelines) (MacDonald et al., 1991). These workshops and other discussions have led to the identification of fourteen additional lessons for monitoring. These lessons are concepts which either were not incorporated into the Guidelines, were not sufficiently emphasized, or which are needed to put the Guidelines in context. The topics include: monitoring as a continuum; defining objectives and hypotheses; peer review; uncertainty and risk; upslope vs. instream monitoring; photo sequences; scale considerations; data storage, data interpretation, and data base management; activities monitoring; and personal commitment as a critical component in monitoring projects. Many of these lessons might appear self-evident, but our experience indicates that they are often ignored. Like the Guidelines, these lessons are widely applicable and should be explicitly recognized when formulating and conducting monitoring projects.     

Impacts of logging and wildfire on an upland black spruce community in northwestern Ontario

Plant species composition and community structure were compared among four sites in an upland black spruce community in northwestern Ontario. One site had remained undisturbed since the 1930s and three had been disturbed by either logging, fire, or both logging and fire. Canonical correspondence ordination analyses indicated that herbaceous species composition and abundance differed among the disturbance types while differences in the shrub and tree strata were less pronounced. In the herb stratum Pleurozium schreberi, Ptilium crista-castrensis and Dicranum polysetum were in greatest abundance on the undisturbed forest site, while the wildfire and burned cutover sites were dominated by Epilobium angustifolium and Polytrichum juniperinum. The unburned harvested site was dominated by Epilobium angustifolium, Cornus canadensis and Pleurozium schreberi. Species richness was lower on the undisturbed site than on any of the disturbed sites while species diversity (H) and evenness (Hill's E5) were higher on the unburned harvested site than on the other sites. Results suggest that herb re-establishment is different among harvested and burned sites in upland black spruce communities and we hypothesize that differences in the characteristics of the disturbance were responsible, in particular, the impact of burning on nutrient availability. These differences need to be taken into account in determining the effects of these disturbances on biodiversity and long-term ecosystem management.