Anchorage of coniferous trees in relation to species, soil type, and rooting depth

Abstract

A database was constructed of tree-anchorage measurements from almost 2000 trees from 12 conifer species that were mechanically overturned on 34 sites in the United Kingdom between 1960 and 2000. Anchorage was compared among species, soil groups (freely-draining mineral, gleyed mineral, peaty mineral, and deep peat) and root depth classes (shallow, <40 cm; medium, 40–80 cm; and deep, >80 cm) using regressions of critical turning moment against stem mass. Sitka spruce (Picea sitchensis (Bong.) Carr.) was used as a benchmark because it formed the largest part of the database and was the only species with all soil-group and depth-class combinations. Anchorage of Sitka spruce was strongest on peat and poorest on gleyed mineral soils. Deep rooting increased critical turning moments by 10%–15% compared with trees of equivalent mass with shallower roots. Significantly better anchorage than Sitka spruce was found for grand fir (Abies grandis (Dougl. ex D. Don) Lindl.), with various rooting depths on freely draining and gleyed mineral soils and for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) on medium-depth mineral soil. Lodgepole pine (Pinus contorta Dougl. ex Loud.) had poorer anchorage than Sitka spruce over a range of soil groups and root depth classes. Norway spruce (Picea abies (L.) Karst.) on shallow gleyed mineral soil, and Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) on medium depth mineral soil, also had poorer anchorage. Other combinations had similar anchorage to the equivalent Sitka spruce. These results are discussed with respect to the development of forest wind-risk models.

The influences of forest stand management on biotic and abiotic risks of damage

“…Adverse conditions in the rhizosphere leading to lesions of the root system render forest stands especially susceptible to fungal diseases and windthrow. Any factor that decreases rooting depth, such as frequent waterlogging (Laiho, 1987;Offergeld, 1986;Poeppel, 1994;Schreiner et al, 1996;Van Nispen tot Sevenaer, 1975) or soil compaction (Andersen, 1954) can negatively affect anchorage (Nicoll et al, 2006). The effect of such adverse conditions on stand stability varies with the tree species, as well as the rooting system's ability of adaptation (Nicoll and Ray, 1996;Xu et al, 1997).…”

Understanding the Impact of Root Morphology on Overturning Mechanisms: A Modelling Approach

“…Sitka spruce (Picea sitchensis; see Nicoll et al, 2006a), maritime pine (Pinus pinaster; Stokes, 1999;Cucchi and Bert, 2003;Danjon et al, 2005) and balsam fir (Abies balsamea; Ruel et al, 2000Ruel et al, , 2003Achim et al, 2005). However, it is not yet known which shape of root system is best for increased tree mechanical stability.…”

Windthrow Dynamics in Boreal Ontario: A Simulation of the Vulnerability of Several Stand Types across a Range of Wind Speeds

“…However, using winching data from other regions is standard within the global set of hybrid-mechanistic windthrow prediction models [42], and where these models have been validated, has been shown to be reasonable [43]. We also believe the use of surrogate species is reasonable since often species from the same genus show similar relationships [15,[43][44][45][46][47][48][49][50][51][52][53] between stem mass and critical turning moment. However, as local data on windthrow outcomes become available, in particular data from thunderstorms (summer wind storms), simulated outcomes can be checked, parameter values updated, and the simulations re-run.…”