Mature Forest Ecosystems Research Articles

Effects of elevation and forest cover on winter birds in mature forest ecosystems of southern British Columbia

Winter diversity, distribution, and density of nonmigratory birds were examined in six mature forest ecosystems from two study areas in southern British Columbia. Forest age ranged from 91 to 150 years and the ecosystems ranged from 500 to 2100 m above sea level. Sampled forest stands had no previous history of logging and were a minimum 30 ha in size. The main objectives of this study were to measure nonmigratory birds in relation to elevation and to percentage of stand-level lodgepole pine composition. Twenty-one nonmigratory bird species totaling 2747 observations were detected at 775 point-count stations in 107 stands using 10-min unlimited-distance point counts. Pine siskins (Carduelis pinus (Wilson, 1810)), red-breasted nuthatches (Sitta canadensis L., 1766), and red crossbills (Loxia curvirostra L., 1758) were the three most commonly detected species. Mature forests at low elevation had between 1.7 and 3.5 times more species and between 2.0 and 4.7 times more birds than forests at high elevation. In addition, species richness and bird density declined with increasing stand-level composition of lodgepole pine. We suggest that low-elevation ecosystems be given high priority in coarse-filter management of winter bird habitat.

The isotopic composition of soil organic carbon on a north–south transect in western Canada

SummaryThe minor isotopes of carbon (13C and 14C) are widely used as tracers in studies of the global carbon cycle. We present carbon‐isotope data for the 0–5 cm layer of soil on a transect from 49.6°N to 68°N, from mature forest and tundra ecosystems in the boreal‐arctic zone of interior western Canada. Soil organic carbon in the < 2000 μm fraction of the soil decreases from 3.14 kg m−2 in the south to 1.31 kg m−2 in the north. The 14C activity of the organic carbon decreases as latitude increases from 118.9 to 100.7 per cent modern carbon (pMC). In addition, the 14C activities of organic carbon in the particle‐size fractions of each sample decrease as particle size decreases. These results suggest that organic carbon in the 0–5 cm layer of these soils transfers from standing biomass into the coarsest size fractions of the soil and is then degraded over time, with the residue progressively transferred into the more resistant finer particle sizes. We calculate residence times for the coarsest size fractions of 21 years in the south to 71 years in the north. Residence times for the fine size fractions (< 63 μm) are considerably longer, ranging from 90 years in the south to 960 years in the north. The δ13C of the organic carbon decreases from −26.8 ± 0.3‰ in soil under forest in the south to −26.2 ± 0.1‰ for tundra sites in the north. At all sites there is an increase in δ13C with decreasing particle size of 0.7–1.6‰. These changes in δ13C are due to the presence of ‘old’ carbon in equilibrium with an atmosphere richer in 13C, and to the effects of microbial degradation.

Rising CO2– future ecosystems

Rising CO₂– future ecosystems

Changes in streamwater chemistry after 20 years from forested watersheds in New Hampshire, U.S.A.

Long-term patterns of streamwater chemistry provide valuable evidence of the effects of environmental change on ecosystem biogeochemistry. Observations from old-growth forests may be particularly valuable, because patterns should not be influenced by forest succession. Water samples were collected biweekly from four streams in, and near, the old-growth forest watershed of the Bowl Research Natural Area in the White Mountains of New Hampshire from May 1973 through October 1974, and from June 1994 through June 1997. Average NO3– concentrations, which ranged from 40.8 to 46.1 µequiv.·L-1 in 1973-1974, declined significantly to averages of 14.9-20.1 µequiv.·L-1 during 1994-1997. Concentrations of the base cations, Ca2+ and Mg2+, also declined in stream water between the two sampling periods. The northeastern United States, including the study area, has been subjected to elevated atmospheric deposition of sulfur and nitrogen for more than 40 years. This observation has led to the concern that mature forest ecosystems may exhibit N saturation and depletion of Ca2+ from exchangeable soil pools. While the Bowl exhibits a pattern of elevated concentrations of NO3– throughout the year, suggestive of conditions of N saturation, concentrations have declined markedly over the last 20 years. Concentrations of Ca2+ have also declined suggesting possible depletion from the exchangeable soil pool, but the acid neutralizing capacity of stream water has remained constant or increased, indicating resistance to additional acidification.

Ectomycorrhizae of Young and Mature Scots Pine Trees in Industrial Regions in Poland

Ectomycorrhizae are obligate symbiotic structures of forest tree roots and are susceptible to environmental changes. Ectomycorrhizae of Scots pine ( Pinus sylvestris L.) trees grown in forests influenced by different levels of air pollutants were investigated. Total numbers of mycorrhizal root tips in the soil horizons and the frequency of mycorrhizal morphotypes were studied as indicators of ectomycorrhizal status. The studies were conducted in two comparable young plantations in western Poland with high and low pollution exposure and in two mature forest ecosystems in southern Poland differing in pollution exposure. At the young Scots pine plantation with high pollution exposure (Luboń), numbers of mycorrhizal root tips in the soil layer 0–5 cm were lower during three growing seasons than at the cleaner site (Kórnik). In the soil layer 15–30 cm the total number of mycorrhizal root tips was found slightly higher at the polluted than at the control site. There was no difference in the frequency of the seven mycorrhizal morphotypes found at the two young plantations. At the heavily polluted mature forest stand (Niepołomice Forest) the total number of mycorrhizal root tips was lower in zones of severe pollution levels than in the less polluted zones. Moreover, the average number of mycorrhizae in the Niepołomice Forest was lower than in the moderately polluted forest ecosystem (Ratanica catchment). The mycorrhizal diversity of the mature pines in the heavily polluted forest was reduced (four morphotypes) as compared to the moderately polluted forest (eight morphotypes). The relationship between industrial pollution and mycorrhizal status was more pronounced at the mature Scots pine stands than at the young plantations.

Wood decomposition, higher fungi, and their role in nutrient redistribution

Dead wood litter input to mature forest ecosystems represents 30–40% of the total biomass, containing about 1–4 and 0.1–0.8 kg/(ha∙year), of N and P, respectively. However, since wood decomposes relatively slowly, it represents a much larger proportion of the standing crop of plant litter on the forest floor, forming a large reservoir of mineral nutrients, which are unavailable for primary producers until they are released by decomposer organisms, primarily basidiomycetes and to a lesser extent ascomycetes. Readily available nutrients are utilized rapidly leaving other nutrients locked up in the recalcitrant lignocellulose complex. As decomposition proceeds the relative concentration of N and P in wood increases (i.e., carbon/nutrient ratio decreases), as C is lost as CO2, but these nutrients are rapidly sequestered in mycelial biomass. Formerly it was thought that nutrients were released when the carbon/nutrient ratio of the wood approximated that of mycelium. However, fungi are inherently greedy using excess nutrients for production of reproductive structures and foraging mycelium. The latter, which is often aggregated to form rhizomorphs or cords, grows out of wood in search of new resources, often forming extensive long-lived networks that exhibit remarkable patterns of reallocation of fungal biomass and nutrients. Within these systems, nutrients are conserved and are often relocated for many metres and may aid in establishment of mycelia in new resources. Nutrients are probably largely released when mycelia are grazed upon by invertebrates, nonbiotically damaged, interact with other fungi and bacteria, or die. Key words: ecology, lignocellulose, basidiomycetes, rhizomorph, translocation.

Effects of global change on carbon storage in tropical forests of South America

We used a process‐based model of ecosystem biogeochemistry (MBL‐GEM) to evaluate the effects of global change on carbon (C) storage in mature tropical forest ecosystems in the Amazon Basin of Brazil. We first derived a single parameterization of the model that was consistent with all the C stock and turnover data from three intensively studied sites within the Amazon Basin that differed in temperature, rainfall, and cloudiness. The range in temperature, soil moisture, and photosynthetically active radiation (PAR) among these sites is about as large as the anticipated changes in these variables in the tropics under CO2‐induced climate change. We then tested the parameterized model by predicting C stocks along a 2400‐km transect in the Amazon Basin. Comparison of predicted and measured vegetation and soil C stocks along this transect suggests that the model provides a reasonable approximation of how climatic and hydrologic factors regulate present‐day C stocks within the Amazon Basin. Finally, we used the model to predict and analyze changes in ecosystem C stocks under projected changes in atmospheric CO2 and climate. The central hypothesis of this exercise is that changes in ecosystem C storage in response to climate and CO2 will interact strongly with changes in other element cycles, particularly the nitrogen (N) and phosphorus (P) cycles. We conclude that C storage will increase in Amazonian forests as a result of (1) redistribution of nutrients from soil (with low C:nutrient ratios) to vegetation (with high C:nutrient ratios), (2) increases in the C:nutrient ratio of vegetation and soil, and (3) increased sequestration of external nutrient inputs by the ecosystem. Our analyses suggest that C:nutrient interactions will constrain increases in C storage to a maximum of 63 Mg/ha during the next 200 years, or about 16% above present‐day stocks. However, it is impossible to predict how much smaller the actual increase in C storage will be until more is known about the controls on soil P availability. On the basis of these analyses, we identify several topics for further research in the moist tropics that must be addressed to resolve these uncertainties.

Wood (delta)^(13)C as a Measure of Annual Basal Area Growth and Soil Water Stress in a Pinus Strobus Forest

The relationships between annual wood tissue °13C, growing season soil water potential, and basal area growth were studied in a mature, white pine (Pinus strobus) stand at the Coweeta Hydrologic Laboratory, in western North Carolina. In 1992, four bolewood cores that spanned the years from 1980 to 1989 were extracted from each of ten equal—size, co—dominant white pine trees within the stand. The 1980s were a time of extreme climate with some of the hottest, driest, and wettest years recorded at Coweeta. Annual basal area growth ranged from 14.5 to 25.0 cm2°tree—1°yr—1, and modeled values of average growing season soil water potential ranged from —0.21 to —5.58 MPa, when measured to a depth of 60 cm. After correcting annual wood tissue °13C for atmospheric changes in °13C, carbon isotopic discrimination (△) ranged from 18.52 to 19.62%. The △ of annual wood tissue was positively correlated with average growing season soil water potential (r2 = 0.74, P = 0.0005, n = 10 growing seasons) and average annual basal area growth (r2 = 0.78, P = 0.0005, n = 10 seasons). Basal area growth and growing season soil water potential were also correlated (r2 = 0.64, P = 0.002, n = 10 seasons). These results suggest that annual wood tissue °13C could potentially be useful in estimating historic changes in soil water potential and basal area growth in mature forest ecosystems.

Physiological controls of the carbon balance of boreal forest ecosystems

Mature boreal forest ecosystems in interior Alaska are large annual carbon sinks. Annual tree production is the largest carbon flux. A model of that combined energy, heat, and moisture exchange, tree photosynthesis and respiration, decomposition, and nitrogen mineralization was used to examine the physiological controls of the carbon balance of boreal forests. Simulated annual tree production, forest floor decomposition, nitrogen mineralization, and soil respiration were not significantly different from observed data for nine black spruce (Piceamariana (Mill.) B.S.P.), five white spruce (Piceaglauca (Moench) Voss), two quaking aspen (Populustremuloides Michx.), two paper birch (Betulapapyrifera Marsh.), and three balsam poplar (Populusbalsamifera L.) forests near Fairbanks, Alaska. The model also reproduced features of observed fertilization, soil warming, and litter transplant experiments. Net carbon uptake during tree growth was the largest simulated carbon flux, and these analyses suggest that differences in the carbon balance of these forests can be explained, in part, through key physiological parameters that link photosynthesis, carbon allocation, nitrogen requirements, litter quality, and foliage longevity. The simulations suggest that the greatest source of variation in these parameters occurs between coniferous and deciduous life-forms not among species. Simulation experiments showed that the coniferous and deciduous physiological parameters maximized annual tree production for coniferous and deciduous forests, respectively, thereby providing a physiological basis for the evolution of the different life history characteristics of deciduous and coniferous species. The strong coherency among physiological parameters allows them to be estimated from easily obtained data and may provide a basis to examine carbon fluxes over large regions.

A decennial control of N-cycle in the Belgian Ardenne forest ecosystems

As a rule, N-supply of mature Ardenne forest ecosystems is satisfactory. Mineralization rates of soil organic matter are generally high and nitrogen is not a frequent nor an important growth limiting factor. Light N-deficiency is likely to depend on unsatisfactory root absorbing power in very acid soils with dysmoder humus. For other major elements, especially for Mg, Ca and P, near optimal nutrition is rarely observed. During the late sixties, fertilizer experiments have shown that nutrition equilibrium of stands growing on acid soils, poor in exchangeable Mg, is very sensitive to artificial NH4-addition. Mg-deficiency symptoms have been induced. The present continuing atmospheric NH 4 input is believed to produce similar but lasting nutritional stress which might be accentuated by additional acidity generated during nitrification of excess NH 4. Evolving Mg deficiency leads to trees' death and developing forest decline is likely to enhance N-output under NO3-form. Awaiting adequate air purification, fertilizing should restore nutrition equilibrium in order to save damaged stands, to slow down soil acidification and to incorporate excess atmospheric N-input into improved biomass production.

Differences between Environmental Impacts of Logging and Recreation in Mature Forest Ecosystems

In order to be able to recommend the most compatible land-uses for adoption in a multiple land-use system, in terms of the resultant impacts on soils and vegetation in mature ecosystems, the impact of logging operations and recreation in the Caspian region of Iran was studied. Four forest communities were selected and, with an analytical approach, the bulk density, percentage of plant cover, number of individual plants, plant height, and the number of plant species encountered, in 36 sample plots (20 × 1 m) located on various slopes and aspects, and used for logging or recreation at different intensities (unused, transitional, used), were recorded.The effectiveness of data, in terms of demonstrating the statistically significant differences, was tested by the method described in Conquest (1983). T-statistics for two means were used to discern statistical differences.The results of the study indicate that the effect of logging is greater than that of recreation on soil bulk density, whereas the effect of recreation is greater on plants than that of logging. Aspect has no effect on the resultant impact, but steep slopes are more susceptible than gentle ones. With increases in altitude, the degree of impact decreases. Ecosystems having loamy clay soils and a greater proportion of monocotyledonous than dicotyledonous species, located on gentle slopes at the higher altitudes investigated, tend to resist the impacts of both logging and recreation best.

Sediment and nutrient discharge through streamflow from two experimental watersheds in mature oak-beech forest ecosystems near Istanbul, Turkey

Initial results concerning the seventeen months of the calibration phase of a paired watershed experiment are summarized. The water discharge from watershed IV is usually higher during the rainy season than that from watershed I, but this trend reverses during the dry season. Annual suspended sediment loads are low, of the order of 60–80 kg ha −1 yr −1. Mg, and particularly Ca and HCO 3 concentrations vary inversely with the rate of streamflow. Average monthly loss of nutrients has significant correlations with streamflow. Regression equations for these relations are presented. Annual losses of Ca, Mg, Cl, HCO 3 and Na are substantially higher than for K, N and P. The losses of N are 3—4 kg ha −1 yr −1 and those for P around 0.4 kg ha −1 yr −1.

An Evaluation of Aerial Survey Techniques for Red-Cockaded Woodpeckers

The efficiency of using a fixed-wing aircraft to locate red-cockaded woodpecker (Picoides borealis) colonies in pine (Pinus spp.) forests of the southeastern United States was tested during 1980-82 using inexperienced observers under clear skies in summer and under clear and overcast skies in winter. Later, under actual survey conditions with experienced observers, preliminary superficial coverage of the area from the ground followed by intensive coverage from the air resulted in location of 80% of the colonies that were later found by intensive ground survey. In both experimental and actual surveys, successful aerial location of colonies was based on: (1) high visibility of gum on the trunks of cavity trees above and below redcockaded woodpecker cavities; (2) species preference for excavating in pines located in relatively open stands; (3) species habit of typically excavating cavities below the lowest branch; and (4) usual presence of multiple cavity trees per colony. Flight altitude was approximately 150 m and flight speed 60 knots in both Cessna 150 and 172 aircraft. Highest accuracy can probably be attained by double coverage of the area using perpendicular transects on calm, overcast, winter days. Aerial surveys can be used to locate colonies of redcockaded woodpeckers on inaccessible areas or in situations where intensive ground survey is not feasible. J. WILDL. MANAGE. 49(4):1083-1088 The red-cockaded woodpecker is an endangered species that is endemic to the mature pine forest ecosystems of the southeastern United States. Because its home range often exceeds 80 ha, the species is limited to large tracts of forest and, consequently, is difficult to census. Estimates of red-cockaded woodpecker abundance can, however, be made by extrapolating from the number of active sites. Although the species is not truly colonial, the colony is occupied by a clan, usually consisting of a breeding pair and one or more nonbreeders (generally male offspring from previous seasons). Typically each bird in a clan has a roosting cavity in a living mature pine, and the cavities of each clan are clustered in nearby trees. Colony sites are traditional, being used by succeeding generations of birds and often include cavities that have been abandoned by red-cockaded woodpeckers or usurped by other species. Cavity trees take on a conspicuous appearance due to the excavation of resin wells, from which gum flows, around the cavity entrance, eventually coating the tree with a white glaze (Hooper et al. 1980). When a cavity has been abandoned, the gum dries, turning yellow-white at first, but eventually darkens as a result of bei g covered by soot from fires or by dust from he air. The conspicuousness of the cavity trees is increased because cavities generally are below the lowest branch and open to the south or west (Locke and Conner 1983). Furthermore, vegetation in an active is typically open-at least at cavity height (Hooper et al. 1980). Because of the extensive forested areas f the Southeast, locating sites by systemati ally searching suitable habitat from the groun is labor-intensive and costly. The objectiv s of the study were to evaluate: (1) the eff ctiveness of using fixed-wing aircraft to locate prev ously unknown colonies, and (2) the abilities of observers to locate known sites from the air at different times of year, under different weather conditions. The exp riment was funded by the U.S. For. Serv. Southeast. For. Exp. Stn., Clemson Univ., through Coop. Res. Agreement 18-750. Surveys we e funded under contracts to Eco-Inventory Stud., Inc., from the U.S. For. Serv., U.S. Army Corps of Eng., U.S. Bur. of Land Manage., and United Gas Pipeline. M. R. Lennartz provided encouragement and stimulating discussion throug out the study. B. J. Schardien Jackson assisted with the experimental study and surThis content downloaded from 207.46.13.131 on Sat, 15 Oct 2016 04:20:31 UTC All use subject to http://about.jstor.org/terms 1084 RED-COCKADED WOODPECKER AERIAL SURVEY * Jackson J. Wildl. Manage. 49(4):1985

Sitka Black-Tailed Deer Winter Range in the Kadashan Bay Area, Southeast Alaska

Late winter use of mature forest ecosystems by deer (Odocoileus hemionus sitkensis) in the Kadashan Bay area of southeast Alaska was evaluated. Use, measured by track observations, was highest in ecosystems under 50-meter elevation which supported heavily stocked old-growth timber stands. These sites had the least snow accumulation during the critical late winter period. It was concluded that if large blocks of low elevation timber in the study area were clearcut the carrying capacity of the winter range would not be maintained.

Stress Effects on Bird-Species Diversity within Mature Forest Ecosystems

Two beech-maple forests, one virgin (control) and one selectively cut (experimental), were analyzed in detail for man-made stress effects upon tree-avian community structural relationships. Vegetation analyses revealed that Hueston Woods, a virgin beech-maple forest in southwestern Ohio, was stratified into two distinct canopy layers, whereas Lewis Woods, a previously thinned beech-maple forest in Ecentral Indiana, contained four distinct canopy strata. Although sugar maple (Acer saccharum) and American beech (Fagus grandifolia) were most abundant in both community types, they were truly dominant in terms of importance values in Hueston Woods. Lewis Woods had a more heterogeneous vegetational structure and greater absolute density, species diversity (H'), species richness (D) and species evenness (e) values than Hueston Woods. Lewis Woods resembled an earlier seral stage of ecological succession. This supports the hypothesis that species diversity is less in a climax community than in preclimax conditions. Avian analyses revealed significant differences (p < .05) for the resident evenness (apportionment) values between the two study areas. This difference was consistent through the 10-week (25 April-3 July 1973) observation period. Although Hueston Woods contained 38 resident species within a 15-acre (6.1 ha) study plot as compared to 32 species for Lewis Woods, evenness values were slightly greater for Lewis Woods. These findings support the concept of birds representing an equilibrium taxon in terms of the evenness component of species diversity. This study presents strong evidence that birds do tend to depict and to respond to the overall structure of a major plant community. It is suggested that resident bird populations be considered as indicator taxa when attempting to measure and evaluate the impact of man-made stress on total ecosystems.