Assessing the effect of snow/water obstructions on the measurement of tree seedlings in a large-scale temperate forest inventory
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Forestry. 86: 421-427.
National-scale forest inventories have endeavoured to include holistic measurements of forest health inclusive of attributes such as downed dead wood and tree regeneration that occur in the forest understory. Inventories may require year-round measurement of inventory plots with some of these measurements being affected by seasonal obstructions (e.g. snowpacks and seasonal flooding). In order to assess the potential effects that snow/water obstructions may have on the measurement/analysis of forest seedlings across large scales, the differences in seedling abundance between two inventory measurements (~5-year remeasurement period) and as affected by snow/water depth was ascertained using a repeated forest inventory across the eastern US. Results indicate that there is a general trend of decreasing seedling density over time (-33.16 seedlings ha-1 year-1) in the eastern US, with snow/water depths in excess of 15 cm significantly affecting resulting estimates of seedling abundance. Although snow/water obstruction to seedling measurement occurred on ~9 per cent of inventory plots across the eastern US, snow was a much more common situation occurring on nearly 50 per cent of plots (at time 1, 2 or both) at high latitudes (>45°). Given the statistically significant effect of snow/water on seedling abundance estimates, tree regeneration assessments should not include observations obstructed by snow/water depths that exceed minimum seedling heights. Furthermore, seedling abundance inventories may mitigate the influence of measurement obstructions bysampling only during the summeror incorporating climate information into their sampling logistics.
Woodall, C.W.; Westfall, J.A.; Zhu, K.; Johnson, D.J. 2013. Assessing the effect of snow/water obstructions on the measurement of tree seedlings in a large-scale temperate forest inventory. Forestry. 86: 421-427.