Overall, in both years 3 and 4, the above-ground metrics of the excavated trees provided a good representation of the growth performance of the plot trees.
In this study, above-ground metrics included tree height, canopy spread (i.e. canopy diameter), root-collar diameter (RCD – measured at ground level) and diameter at breast height where applicable (DBH – measured 1.4 m above ground level).
In such studies, equal consideration is given to above-ground metrics including measurement of tree canopy growth (diameter) and its effects on the soil moisture regime of slopes largely through hydrological processes (e.g. interception, evaporation, transpiration) (Stokes et al. 2009).
Measurement methods of both above- and below-ground metrics followed well-established procedures used in earlier studies (Watson et al. 1999; Czernin & Phillips 2005; Marden et al. 2005; Phillips et al. 2014).
Whole trees were excavated and destructively sampled and several below-ground metrics (total root length of all roots > 1 mm in diameter, lateral root spread, total root biomass) assessed.
The most common below-ground metrics used to compare the performance of different species for performing this erosion 'protection' or reinforcement function include root size, biomass, lateral spread, depth, cross-sectional area and the measurement of the strength of individual live, dead and decaying roots.
However, this creates difficulties of interpretation, and other more theoretically grounded metrics that take into account the difference in the level of precision between the original dataset and the generalized data have been suggested [ 5].
Willows performed better than poplars in above-ground growth metrics (net tree height, above-ground biomass) and 3-m poles performed the best of the planting types tested (net tree height, above-ground biomass, below-ground biomass, total root length).
As Winn (1993) states, publications often lack a proper evaluation and theoretical grounding of the metrics used to define distress and the subsequent turnaround success or failure.
Landscape metrics grounded in the landscape ecology literature were used to predict residents' perception of scenic value for each time period.
"We're big believers that the future of the ad industry is going to be grounded in attention metrics, as opposed to impressions, and eye tracking is, hands down, the best way to track attention," Porco says.
