Balsam Fir Forest Research Articles

The chemistry and flux of throughfall and stemflow in subalpine balsam fir forests

The fluxes of water and chemicals in throughfall and stemflow of three subalpine balsam fir forests of New Hampshire, USA were measured. The three fir stands were highly dissimilar in structural characteristics, serving as a test of the importance of stand structure on these fluxes. The sum of throughfall and stemflow water exceeded incident precipitation by more than 18 to 29%. This difference was attributed to the unmeasured input of cloud droplets impacted on canopy surfaces. The principal effect of stand structure was a positive relationship between stand density and stemflow. The flux of NH+4, Na+, SO=4 and Cl− in stemflow was also significantly higher in the most dense stand. The fir canopy effects on capture and chemical alterations of elements were compared with analogous behavior of a nearby deciduous forest. There were several major contrasts, the most striking of which was a flux/canopy pool ratio (leachability index) in the hardwood canopy ranging from two to 32 times higher than in the fir canopy.

Organic matter and major elements of the forest floors and soils in subalpine balsam fir forests

Forest floors, fallen branches and fallen tree boles were sampled in 13 balsam fir (Abiesbalsamea (L.) Mill.) stands in the subalpine zone (1220–1450 m) of the White Mountains in New Hampshire, U.S.A. These 13 stands were distributed in three sites of contrasting exposure, slope, and rockiness. Soil pits were excavated in three of the stands representing each of the three sites. The ash-free dry weights and major elemental contents of the forest floor and dead wood were compared along chronosequences following natural disturbances, between sites, and with other forest types. No significant trends in these components were found along chronosequence comparisons. For sites that are dissimilar in terms of physical position on the landscape and in the appearance of the trees, compensating biotic and abiotic factors apparently underlie the convergence in forest floor and soil characteristics, thereby eliminating site differences as well. The forest floor is massive; ash-free dry weight averages 92 200 kg•ha−1. Total soil profile ash-free weight is 323 600 kg•ha−1. The forest floor and mineral soil horizons are unusually rich in nitrogen and phosphorus, with weighted average ash-free nitrogen and phosphorus concentrations of 2.42 and 0.23%, respectively, in the forest floor. Total nitrogen and phosphorus contents of the forest floor are 2300 and 217 kg•ha−1, respectively. The weight and nitrogen and phorphorus contents of the fir forest floor are greater than that found in other regional forests and coniferous forests in general.

Natural Disturbance and the Steady State in High-Altitude Balsam Fir Forests

Wind-induced, cyclic waves of death, regeneration, and maturation constantly move through the high-altitude balsam fir forests in the northeastern United States. Biomass and productivity relations, species diversity, and nutrient cycling patterns are closely tied to this cycle of disturbance. Disturbance is thus an integral part of the long-term maintenance of this ecosystem. Since forests of this type normally include all phases of the disturbance-regeneration cycle, they may constitute a steady-state ecosystem in equilibrium with the surrounding environment.

Loss of Mass and Chemical Change in Decaying Boles of a Subalpine Balsam Fir Forest

Decay of balsam fir (Abies balsamea) boles was examined in an upper subalpine forest of the White Mountains, New Hampshire, USA. Fifty percent of the initial mass was los in 23 yr; 90% was lost in 77 yr. High decay rates were attributed to the small diameters of the boles, ample moisture, and a nitrogen—rich environment. Average dead woods mass in this forest was 4.9 kg/m2, representing 25% of the sum of dead wood, live plant biomass, and forest floor organic matter. Changes in density and moisture and in the concentrations and content of various chemical components of the boles were traced over the decay sequence. Changes in the content of cellulose, lignin, carbon and sodium followed loss of mass during decay. Contents of calcium, magnesium, potassium and phosphorus decreased faster than loss of mass in the early stages of decay. Much of this initial loss was ascribed to sloughing of nutrient—rich bark which in these small boles comprised 13% of dry mass. Later in decay, the loss rates of calcium, magnesium and potassium were about the same or slightly less than the loss rate of mass. After a steep initial drop, phosphorus content of the boles remained approximately constant between years 12 and 33. Thereafter the loss rate paralleled loss of mass. Nitrogen content was approximately constant in the first 33 yr after which it declined in parallel with loss of mass.

Niche and Habitat Relations in Subalpine Bird Communities of the White Mountains of New Hampshire

The populations, foraging behavior, and habitat selection of 20 insectivorous species of subalpine birds were studied during three breeding seasons in the white Mountains, New Hampshire, USA. The object was to clarify how an elevation gradient of environmental adversity affected diversity, dominance, niche, habitat, and species biology. Population densities and territory sizes were measured from census plots. Territory sizes correlated with species body mass, probably in response to size—related food requirements. Lower elevations had more even distributions of densities among species and less steep dominance—diversity curves than did higher elevations. To show habitat selection patterns in the subalpine vegetation, principal components analysis (PCA) was used to develop a model that emphasized elevation and broadleaf—to—coniferous foliage as the two major gradients. Bird species diversity (BSD) reached a maximum in well—developed preclimax red spruce—balsam fir forests with some broadleaf crowns present. Individual species responses were mapped using the model as a base chart, grouping together: (1) five species living at altitudes above 1100 m with small differences in their specific patterns, (2) five other species widely distributed through the mid—subalpine zone (800—1100 m), (3) six more mid—subalpine species segregating along the broadleaf/conifer foliage gradient, and (4) three species found near water. Niche relations were studied using detrended correspondence analysis, a modified version of reciprocal averaging. Resource use was divided by (1) terrestrial vs. arboreal position, (2) a gradient from fine distal (leaves) to coarse proximal (trunk) substrates, and (3) different specializations for food acquisition. BSD was greater in the resource categories requiring less energy and less specialized morphological adaptations to exploit, or having greater insect resource bases. To investigate the relations between habitat and niche, a matrix of the correlations between the niche and habitat variables, using species means for data, was analyzed by PCA. Three relations emerged: (1) the elevation/forest structure gradient was correlated with the terrestrial/arboreal foraging segregation, (2) the niche substrate gradient responded to vegetation structure along the broad—leaf/conifer gradient, and (3) in both cases the response of foraging behavior to habitat structure involved many variables acting together. Niche and habitat were thus closely linked as aspects of species ecotopes; species responses were illustrated for the Blackpoll Warbler and other wood warblers. Food was inferred to limit populations occasionally, so that interspecific competition plausibly underlies niche differentiation. Thermoregulation is hypothesized to affect habitat selection.

Structure and Biomass Dynamics of Epiphytic Lichen Communities of Balsam Fir Forests in New Hampshire

Changes in species composition, cover, biomass, and elemental pools in space and time were determined for epiphytic lichens associated with balsam fir (Abies balsamea [L.] Mill.) forests on Mt. Moosilauke, New Hampshire, USA. Thirty—three species of epiphytic lichens were present; none was able to fix atmospheric nitrogen. Between 45 and 94% of the total lichen flora occurred in any given stand. Hypogymnia physodes, H. krogii, Bacidia chlorococca, Platismatia glauca, Hypotrachyna revoluta, and Parmelia saxatilis were the leading dominants in all stands and accounted for 74—93% of the bole cover. Each species exhibited an individualistic pattern of vertical distribution. Lichen cover was least in the lower part of the bole (<15%) and peaked in the mid— or top—canopy position (42—58%). Species richness, average percent bole cover, and epiphytic lichen biomass increased with stand age owing to change in stand structure. Lichen biomass ranged from 120 to 1603 kg/ha, with °80% of the biomass located on branches. Nitrogen and phosphorus concentrations increased with increasing canopy height, while no obvious trends were noted for calcium, magnesium, or potassium. Elemental pool sizes (average biomass multiplied by average lichen tissue concentration) were: 10.7 kg/ha for nitrogen, 3.34 for potassium, 1.26 for calcium, 1.20 for phosphorus, and 0.25 for magnesium. Epiphytic lichens contribute little (<1.0%) to biomass and elemental pool sizes within the balsam fir ecosystem.

Solution Chemistry of a New Hampshire Subalpine Ecosystem: A Biogeochemical Analysis

Field studies were conducted to examine the processes and environmental factors which influence or control ion transport in ecosystems receiving chronic acid precipitation. Specifically, these studies focused on changes in solution chemistry during rainfall percolation through a cool, moist balsam fir forest in the subalpine zone of the White Mountains of New Hampshire. Patterns of solution chemistry exhibit the following distinctive trends: (1) atmospheric sulfate is the dominant anion in the leachate from this system, although organic ligands were probably the major anionic species in solution in the past; (2) soil aluminum leaching appears to be increasing in response to acid precipitation, resulting in comparatively high dissolved aluminum concentrations in the soil solution; and (3) most neutralization of atmospheric sulfuric acid occurs at depth in the mineral soil, rather than in the fir forest canopy or forest floor. The behavior of individual ions in the fir zone system appears to depend upon the differential effects of the following major factors: atmospheric input rates, biological demand, ion exchange affinities, acidity of the percolate, and rates of ion release and consumption in weathering, mineralization, and geochemical buffering reactions.

A pattern of forest types on ribbed moraines in eastern Newfoundland

A distinctive pattern of forest types has been observed on ribbed moraines of the Avalon Peninsula, Newfoundland. This previously unreported pattern is interesting in that the best forests occur on the exposed tops and the theoretically less favourable north slopes. On each moraine, the south slopes characteristically had an uncommercial forest of balsam fir (Abiesbalsamea (L.) (Mill.)) and black spruce (Piceamariana (Mill.) BSP.), the top and upper north slopes had a forest of white birch (Betulapapyrifera Marsh.) and balsam fir, and the lower north slope had a pure balsam fir forest. Site descriptions are provided for each forest type and the vegetation succession following fire is proposed.

Gaseous Loss of Ammonia Following Urea Application in a Balsam Fir Forest

Nitrogen losses through ammonia volatilization increased with increasing rates of application and were 6.8% of 112 kg urea-N/ha after 10 days. Initial humus moisture content within the limits studied affected volatilization rates in the first days but had little effect on overall losses. A discontinuous ammonia-trapping technique for field use is discussed.

The Use of Mathematics and Computers to Determine Optimal Strategy and Tactics for a Given Insect Pest Control Problem

AbstractA computer program has been developed for use in evaluating various strategies of insect pest control. At its present stage of development, the program simulates the effects of various dosages of insecticide, parasite release, and spraying of virus, or any combination of these, weather and pest density on reproduction, dispersal and mortality in a pest population. Effects of changing pest densities on the parasite population and on tree growth and mortality in a hypothetical, 6.4 million-acre balsam fir forest are simulated. Also, the computer simulates dispersal of parasites and disease incidence. All computations are performed separately for each of 625 4-mile-by-4-milc hypothetical squares of forest area in the hypothetical 10,000 square mile area. All operating costs and losses due to lost tree growth and tree mortality are printed each year. The particular set of strategies to be used in each game is included in the input data for each 35-year computer experiment, along with data on physiological parameters, allowable pest thresholds for each type of control, genetic parameters, behavioristic and dispersal data and costs of control. One play of the game takes 50-120 seconds on an IBM 7090 computer, depending on the array of strategies selected.There were a number of significant conclusions from the simulation study. Biological control agents can not be as effective as insecticides unless they keep the pest at very low levels indefinitely. If they only drop the pest to about 10% of the peak level it would have attained without control, this may not be good enough to save the trees, because lethal effects accumulate. That is, pest densities which are not quite high enough to kill a tree quickly can kill it if the pest persists at these densities for several consecutive years. However, by selecting biological control agents with optimal physiological parameters, biological control can be made to produce totally effective control.For all kinds of control, control is vastly more effective if applied 10 years or more before peak pest densities. Therefore, potential pests should be subjected to preventive control at pre-pest densities, rather than being allowed to reach critical densities. The latter policy ignores the hazard of successive years of sublethal pest densities whose effects can cumulate to become lethal. It should be noted, however, that this conclusion follows from exploration of a hypothetical situation, and might not be applicable when considered relative to the exigencies of an actual field problem.

Spruce Budworm Parasite Studies in Northwestern Ontario

The extensive coniferous stands in northwestern Ontario have been subjected to repeated widespread outbreaks of the spruce budworm, Choristoneura fumiferana (Clem.) (5). About 1939 two such outbreaks originated almost simultaneously, one on the west shores of Lake Nipigon and the other south of Lac Seul approximately 180 miles farther west. Each outbreak eventually covered thousands of square miles and was responsible for the destruction of hundreds of square miles of balsam fir forest. Studies of the parasite complex attacking the spruce budworm in northwestern Ontario and the assessment of its general influence on budworm population trends were initiated in the Lake Nipigon outbreak in 1946 by Professor N. R. Brown, now of the University of New Brunswick, and were further developed by the senior author from 1947 to 1950. Similar investigations were initiated by the junior author in the Lac Seul outbreak in 1950 and continued until 1954. Studies in both areas were continued on a limited basis until 1956 through the co-operation of several research officers.