ABSTRACT
Almost any type of sample has some utility when estimating population quantities. The focus in this paper is to indicate what type or combination of types of sampling can be used in various situations ranging from a sample designed to establish cause-effect or legal challenge to one involving a simple subjective judgment. Several of these methods have little or no utility in the scientific area but even in the best of circumstances, particularly complex ones, both probabilistic and non-probabilistic procedures have to be used because of lack of knowledge and cost. We illustrate this with a marbled murrelet example.
Subject(s)
Ecosystem , Environmental Monitoring , Models, Statistical , Probability , Environmental Monitoring/methods , HumansABSTRACT
Relationships among elevation, foliar morphology, spectral reflectance, and chlorophyll fluorescence of two co-occurring montane conifers, red spruce (Picea rubens Sarg.) and balsam fir (Abies balsamea [L.] Mill.), were investigated along two transects from 460 to 1460 m on Mt. Moosilauke in the White Mountains of New Hampshire, USA. Spectral reflectance (300-1100 nm wavelengths) and the chlorophyll fluorescence F(v)/F(m) ratio were measured on dark-adapted needles. Foliar morphology (needle size, shape, and mass) and nitrogen concentrations were measured in the laboratory. Reflectance spectra varied between species and with elevation. Two chlorophyll measures, red edge position and a chlorophyll-based difference index (Chl NDI = R750 - R705/R750 + R705), indicated more chlorophyll in fir than in spruce and decreasing chlorophyll with increasing elevation in both species. The structure-independent pigment index (SIPI = R800 - R445/R800 - R680) increased with elevation, indicating an increasing carotenoid : chlorophyll ratio. The photochemical reflectance index (PRI = R531 - R570/R531 + R570), a measure of photosynthetic radiation use efficiency, decreased with increasing elevation up to 1370 m. In the highest elevation site, within the stunted alpine krummholz at 1460 m, PRI was higher than at 1370 m, but still lower than at 1070 m. This same pattern was evident in the chlorophyll fluorescence F(v)/F(m) measurements. These independent indices indicate higher stress in spruce than fir, which may be related to the "spruce decline" reported in the northeastern USA. Results also indicate progressively increasing stress with increasing elevation up to 1370 m. Stress appears to be lower at 1460 m than at 1370 m, despite the harsher conditions at the very summit of Mt. Moosilauke. This may be a consequence of stress-tolerant physiology and/or prostrate architecture.
ABSTRACT
Models to depict the tapering of a tree bole abound in the literature of forest science, and such models are widely used in forestry practice. One important use is the integration of a taper equation to predict the volume of the tree bole. The statistical properties of volume prediction from an integrated taper equation have been obscure. Based on the statistical characteristics of a taper model for the bole's cross-sectional area, we derive the first two moments of the volume predictor and the prediction error. Bias from the integration is nil. The importance of a reasonable model of the error structure is demonstrated.
