Indicator Of Site Quality Research Articles

TEMPORAL AND SPATIAL PATTERNS IN DAILY MASS GAIN OF MAGNOLIA WARBLERS DURING MIGRATORY STOPOVER

Abstract Whether or not migrants gain mass at a stopover site is an index of site quality. Previous studies have examined mass gain of recaptured birds, and of short-term stopovers by regressing mass at first capture on hour of day. I developed an extension of the latter method using multiple regression to examine the effects on mass gain of hour of day, date, and year. I then used the method to compare the quality of three stopover sites at Long Point, Ontario, for Magnolia Warblers (Dendroica magnolia). At the peak of fall migration, warblers at all three sites gained sufficient mass for a net gain over 24 h, but they gained mass at only two of three sites during spring. Mass gain varied significantly over the course of the day, by date in the season, and among years. The earliest spring migrants lost mass at all sites, but rate of mass gain increased as the season progressed. Similar information for many more species and stopover sites might aid in habitat conservation for migrants.

Temporal and Spatial Patterns in Daily Mass Gain of Magnolia Warblers During Migratory Stopover

Abstract Whether or not migrants gain mass at a stopover site is an index of site quality. Previous studies have examined mass gain of recaptured birds, and of short-term stopovers by regressing mass at first capture on hour of day. I developed an extension of the latter method using multiple regression to examine the effects on mass gain of hour of day, date, and year. I then used the method to compare the quality of three stopover sites at Long Point, Ontario, for Magnolia Warblers (Dendroica magnolia). At the peak of fall migration, warblers at all three sites gained sufficient mass for a net gain over 24 h, but they gained mass at only two of three sites during spring. Mass gain varied significantly over the course of the day, by date in the season, and among years. The earliest spring migrants lost mass at all sites, but rate of mass gain increased as the season progressed. Similar information for many more species and stopover sites might aid in habitat conservation for migrants.

Is height of dominant trees at a reference diameter an adequate measure of site quality?

Based on ecological and stem analysis data obtained from white spruce-dominated stands in the Sub-boreal Spruce of British Columbia, the validity of using height of dominant trees at a specific breast height diameter (20 cm) as an index of site quality was tested. The results indicated that (1) height of dominant trees at 20-cm breast height diameter was related neither to site index (height of dominant trees at 50-year breast height age) nor to ecological measure of site quality (i.e. soil moisture nutrient regimes); (2) taper (diameter : height ratio) did not decrease with increasing site quality; and (3) stand density might have influence height–diameter relationships of dominant trees. Therefore, we conclude that height of dominant trees at a specific diameter is not an adequate measure of site quality.

Site classification in a mixed hardwood forest (Hallerbos, Belgium) with a homogeneous ground vegetation dominated by Hyacinthoides non-scripta (L.) Chouard ex. Rothm.

The forest of Halle (560 ha), situated 20 km south of Brussels is covered by a beech (Fagus sylvatica) forest, locally mixed with secundary species (Tilia, Fraxinus, Acer, Quercus,... ). In almost all stands, herbal vegetation is dominated by bluebell (Hyacinthoides non-scripta). The research intended to classify 36 plots of different tree species composition according to their site quality. Three classification methods were compared: the first one based on the indicator value of the understorey vegetation, a second one on the humus morphology and a last one on some quantitative soil characteristics. According to the plant sociological site classification, the plots have the same site quality. However, humus forms differ apparently and significant differences were found in pH value and base cation saturation of the soil, abundance and biomass of earthworms and biomass of the ectorganic horizon. Tree species proved to be the main cause of these differences. The results illustrate that the herbal vegetation is not always a reliable indicator of site quality. In the case of a homogeneous vegetation dominated by one or more indifferent species, classification on humus morphology or soil analysis are more appropriate. In the forest of Halle, the tree species is probably the main cause of the observed differences in site quality.

Relative stocking index: a proposed index of site quality

Site index is difficult to implement and interpret in multispecies, multiple-aged stands, and its relationship to site factors is obscure. Using data from the USDA forest inventory and analysis (FIA) for the Lake States, we developed log-log relationships between mean tree size and stand density for five cover types. Fits were good, with r2 from 0.96 to 0.98 and slopes from −0.948 to −0.995. We define an alternative index of site quality, the relative stocking index (RSI), as the ratio of a stand's measured density to that predicted using the log–log relationship for its cover type (the norm). We divided the range of RSI into three classes for each type (<0.9 of norm, >0.91 but <1.1 of norm, and >1.1 of norm). Based on analyses of the 1977 and 1990 FIA data from Minnesota, class assignments for individual stands remained constant over that 13-year period. Relationships between site factors and either RSI classes or analogous classes based on site index were examined in a subset of 169 stands. Temperature, precipitation, silt content of surface soil, and calculated annual water deficit all differed significantly among RSI classes, but not among site-index classes. The RSI is easy to apply, robust (resistant to change), and related to site factors. It merits additional examination as an index of site quality, especially in heterogenous stands.

Susceptibility of Norway spruce plantations to white pine weevil attacks in southern Quebec

Annual levels of attack by the white pine weevil (Pissodesstrobi Peck) in 110 Norway spruce (Piceaabies (L.) Karst.) plantations of southern Quebec were measured. The relationships between levels of attack and site and stand characteristics were determined. In 1991, 84% of the plantations were affected by the weevil. Annual levels of attack increased from 2 to 25% of the trees between 1987 and 1991 for the 110 plantations. Drainage and site quality index influenced the levels of attack. On medium-textured soil ecosystems, plantations situated on imperfectly drained soils were significantly more affected (43%) than those on well-drained soils (11%). Plantations located on the most productive sites (site quality index 13–14 m at 25 years) were less affected (8%) than those on the least productive (7–8 m at 25 years) sites (34%). There was no significant correlation between plantation density and levels of attack. The results showed that the white pine weevil is one of the most damaging pests of Norway spruce plantations in southern Quebec. Norway spruce plantations should be monitored annually for damage detection. Appropriate sites should be selected for reforestation to maximize productivity and minimize insect damage.

Expected stand behavior: site quality estimation for southern Appalachian red spruce

An indicator of site productivity and quality was provided for mixed, uneven-aged natural stands of southern Appalachian red spruce ( Picea rubens Sarg.). A set of anamorphic site index curves was developed and validated using the Meyer (1940) nonlinear function using diameter at breast height as a predicting variable. The coefficient of determination for the base curve was good ( R 2 = 0.626) and no consistent bias was detected. Average site quality index decreased with increasing elevation. Site index was highest in pure spruce stands but decreased with increasing elevation and/or increasing Fraser fir ( Abies fraseri (Pursh) Poir.) or yellow birch ( Betula lutea Michaux f.) component.

Soil carbon/nitrogen ratio as a site quality index for some South-east Asian forests

The carbon-nitrogen (C/N) ratio of soil organic matter is related to the patterns of nitrogen immobilization and mineralization during organic matter decomposition by micro-organisms (Swift et al. 1979). Its value decreases as decomposition proceeds (Swift et al. 1979), is negatively correlated with the rate of nitrogen mineralization in decomposition experiments by soil incubation (Tsutsumi 1987a), and can indicate the decomposition rate in terrestrial ecosystems (Jordan 1985). The studies of soil carbon and nitrogen in tropical forest ecosystems (Jordan 1985), such as lowland rain forests (Uhl & Jordan 1984, Yoda & Kira 1982), seasonal forests (Hase & Folster 1982), and montane rain forests (Edwards 1982, Edwards & Grubb 1982), and various types of forests along altitudinal gradients (Marrs et al. 1988, Yoda & Kira 1969), have suggested an increase of the soil C/N ratio with a decrease in temperature and an increase in moisture (Jenny 1941). However, it also depends on the nitrogen contents of the litter itself (Jordan 1985, Swift et al. 1979), local variations in soil conditions according to topography and parent material (Tsutsumi 1987b). In an analysis of the structure and environmental relationships of seven tropical forest stands, Jordan (1985) found that the first principal component, which accounted for 63% of the ecosystem variance, was highly correlated (r = 0.94) with total soil nitrogen. Nitrogen has great effect on plant growth, affecting cell number and cell size (Chapin 1980). The availability of soil nitrogen to plants is determined largely by its mineralization during the decomposition of organic matter (Jordan 1985, Swift et al. 1979). Therefore we may expect a relationship between the C/N ratio and tree growth. This was

Growth intercept as an indicator of site quality for planted and natural stands of Pinus nigra var. pallasiana in Greece

Five-year intercept was found to be a reliable index in site evaluation of both planted and natural stands of black pine. Use of more than five internodes improves the precision of the site-index prediction equation, while using less than five nodal lengths gives inaccurate results. Five-year intercept starting at a point higher than breast height does not significantly improve site-index prediction.

Discriminating between food and space imitation in benthic suspension feeders using self-thinning relationships

Growth and survival have been shown to be density-dependent in many populations of benthic suspension feeders, but it is generally difficult to determine whether food or space is the limiting factor. The study of biomass-density relationships (B-N diagram) in self-thinning situations may provide an additional criterion for such a purpose. It is shown here that the slope of B-N diagrams may vary significantly depending on whether food or space is the Limiting factor When food is Limiting, it varies as a function of the exponent relating respiration to individual biomass. When space is limiting, the slope varies as a function of the length-weight relationship, roughness of the substrate at scales significant to the organisms, and the relationship between individual size and maximum population density. Testing the slopes of B-N relationships may, therefore, provide evidence concerning the nature of the limiting factor. Further, when food is the Limiting factor, the intercept of B-N diagrams is an index of site quality. An example of the use of the B-N diagram for purposes of managing bivalve aquaculture is provided for mussels cultivated on bouchots (intertidal stakes). It is shown that in this particular case, space and food probably alternated seasonally as limiting factors. In addition, under the hypothesis that the entire population is completely harvested on a single occasion, analysis of the B-N diagram provides an estimate of the optimal sowing density in order to minimize competition and avoid subsequent thinning operations. These results illustrate the utllity of managing cultivated populations in terms of biomass and density jointly.

Growth and foliar nutrient concentrations of Pacific silver fir

Nineteen natural stands of Pacific silver fir (Abiesamabilis (Dougl.) Forbes) were assessed for selected site and tree characteristics. The stands, located throughout western Washington, were 26 to 37 years old; they occurred at various elevations (110–1300 m) and on different soil types, and varied greatly in associated plant species. Site index at 50 years breast-high age ranged from 12 to 24 m. Terminal growth per year during the previous 3 years, needle number per centimetre of twig tissue, needle weight and area, and foliar concentrations of 13 elements varied among the 19 stands. Compared with associated western conifers, silver fir had moderate terminal growth, larger and heavier needles, more needles per centimetre of twig tissue, and lower foliar concentrations of N, S, and Mg. There were many significant correlations among the different variables. The foliar nutrient data obtained provide base-line information for future research in nutrition and fertilization of silver fir. These data and the significant correlations between nutrients and site-stand characteristics suggest that (i) silver fir may be more efficient than some western conifers in use of some nutrients, (ii) productivity of silver fir may be improved by application of certain fertilizers; fertilization may be particularly effective during the seedling stage when growth is typically slow, and (iii) levels of some foliar nutrients may be useful as indicators of site quality for silver fir production.

Ponderosa Pine Habitat Types as an Indicator of Site Quality in the Dixie National Forest, Utah

Abstract Forest habitat types have been purported to be useful indicators of site quality. This is generally true for habitat types with different dominant tree species. However, few have studied the site indicator value of habitat types with the same dominant tree species. We measured site index (base age 25) from 172 randomly selected plots within the ponderosa pine (Pinus ponderosa) zone of the Dixie National Forest, Utah. The range of site index within any one habitat type was broad. Poor sites occurred on all five habitat types. However, the best sites occurred only on the Pinus ponderosa/Symphoricarpos oreophilus and Pinus ponderosa/Quercus gambelii habitat types. Therefore, habitat type may be useful in predicting the best sites, but only if other site information is used in addition to habitat type. West. J. Appl. For. 4(2):52-54, April 1989.

Comparing site quality indices and productivity in ponderosa pine stands of western Montana

Four indices of site quality were compared with volume growth of pure, ideal ponderosa pine (Pinusponderosa Laws.) stands in western Montana. Indices based on quantifying the biophysical factors or physiological processes that control productivity (available water index and a relative index of seasonal photosynthesis from computer simulations) worked as well as those based on tree or stand measurements (site index and leaf area index). The following correlations of mean annual stem volume increment were found: with leaf area index, R2 = 0.93; with available water index, R2 = 0.95; with site index, R2 = 0.98; with gross photosynthesis R2 = 0.96. The available water and photosynthesis indices were also highly correlated to site index (R2 > 0.95). However, the tree-dependent site quality indices varied by stand density. Leaf area index and volume growth increased with stand density while site index decreased. Simulations indicated that depletion of soil water effectively halted transpiration and photosynthesis by midsummer and illustrated that even with adequate water, cold spring and fall temperatures ultimately defined the length of the growing season and hence site quality. We conclude that an ecosystem process model can provide an index to site quality independent of tree or stand measurements.

Honduras Pine Spacing Trial Results in Puerto Rico

Abstract Puerto Rico has one of the oldest, continuously measured spacing trials of Honduras pine (Pinus caribaea mor. hondurensis) in existence. At 18 to 20 years, mean survival for all the trial sites except one that suffered hurricane damage in 1979 was 82%. Survival was not related to the triangular spacing treatments of 5, 7, 10, and 14 feet. But spacing did influence diameter growth at all four sites and affected height growth at all but one site Each site had trees ≥100 feet tall at 18 to 20 years; on the two best sites, individual trees reached 90 feet by 12 years. At close spacings, mean annual height increments peaked at 4.0 to 4.5 years on two sites and at 7.2 years on the other two sites. Mean annual diameter increments peaked even earlier, at 3.0 to 3.5 years on the two good sites and at 6.0 years on the two poorer sites. Early effects of competition in reducing both mean annual height and diameter growth, particularly at close spacings, have several managerial implications. The most striking are: (1) underestimating site quality or site index if growth assessments are made only in dense stands, and (2) significant loss of wood volume over long rotations when managers fail to time thinnings before mean annual height and diameter increments decrease.

Distribution of the radiative index of dryness and forest site quality in a mountainous watershed

The radiative aridity index, β (i.e., the ratio of yearly sums of net radiation to those of the latent heat of precipitation), and forest biomass were obtained for 245 terrain segments [Formula: see text] in an Appalachian watershed. A hypothesis was tested that β can be used as a site quality indicator in complex terrain. Regression analysis yielded the following relationship between the average forest biomass of the watershed (Mo = 15.94 kg m−2), the biomass (Mi), the radiative aridity index (βi), and the azimuth (Ai) of terrain segments: Mi/M0 = 2βi[l−Ai/2π + (Ai/2π)4] ± 0.27. The value of the expression in the bracket reaches its maximum for Ai = 0 (north facing slopes), and a minimum for Ai = 227° (southwest facing slopes). A possible interpretation of the obtained relationship is that p represents long term (e.g., daily and seasonal) effects of water and energy exchanges of terrain segments on growth, and the expression in the bracket represents the aspect-related effects of daily fluctuations of microclimate of terrain segments on growth.

Soil and plant water stress in an Appalachian oak forest in relation to topography and stand age

A Forest Site Quality Index (FSQI) formulated to predict site quality in Ridge and Valley terrain based on the topographic parameters of aspect, slope inclination and slope position was used to verify moisture gradients along the southeast face of Potts Mountain in Craig County, Virginia. A gradient of site quality index values representing xeric to mesic sites was established in both recently clearcut and adjacent uncut second-growth forest stands. Soil moisture content was determined gravimetrically at ten day intervals from May to October, 1981. Plant moisture stress measurements were taken in conjunction with soil moisture sampling using the pressure chamber technique on three dominant hardwood tree species. For both clearcut and uncut forest stands, a general gradient of increasing soil moisture availability with increasing FSQI was evident, although differences were not large between index values of 8 and 11 in either stand type. Soil water potential and predawn plant water potential exhibited a strong seasonal trend, their direct relationship suggesting that available soil water is probably the critical factor controlling base P levels. Growth limiting stress levels began in late July and continued for the remainder of the growing season.

Metric Site Index Curves for Eucalyptus grandis

SUMMARY Site index curves and a detailed table of dominant height growth of Eucalyptus grandis in SI units are presented. They are based on previously-established data in imperial units which were fitted to a statistical model, making conversion and use on high-speed data processing equipment practicable. Dominant height, which is used as an indicator of site quality, is defined.

SOME PROBLEMS AND APPROACHES IN CLASSIFICATION OF SITE IN JUVENILE STANDS OF DOUGLAS FIR

Although several easily-determined, single-factor approaches to estimation of site quality are available for use in juvenile stands of Douglas fir (Pseudotsuga taxifolia), not one of them is wholly suitable. Conventional height-age relationships in use are based on scanty data for very young stands, are most representative of fully stocked stands, and depend considerably upon the yield table used as a reference.Recently the growth-intercept method (Wakeley, 1954) has been developed independently for Douglas fir by Wiley (1951) and tested fairly generally by Warrack and Fraser (1955). The growth-intercept method employs the lengths of the first few internodes above breast height as indicators of site quality. This method has the advantages of direct measurement and early classification but indicates current or juvenile site qualities rather than total site capabilities over a long period of time. The utility of another measure of site quality, number of years to reach breast height, is demonstrated by data secured in this study. Schmidt (1954) illustrated possible uses of stump diameters to indicate site quality; unfortunately only past site quality is estimated and direct examination of stumps is necessary. Topographic positions (ridge, upper slope, lower slope, and valley) are, in themselves, often indicative of site quality. Species and abundance of lesser vegetation will also provide indications of the site quality of Douglas fir, but these interrelationships are often complicated and require interpretation by experts. This report illustrates certain problems and possible uses of most of the above-mentioned methods. In addition problems of age-class distribution and succession are discussed. Data used were collected in Douglas fir types on the University Research Forest at Haney and on Vancouver Island.