Exposed roots as indicators of geomorphic processes: A case study from Polylepis mountain woodlands of Central Argentina

CHARTIER, M. P.; GIANTOMASI, M. A; RENISON, D.; ROIG, F.A.

Dendrochronologia

ELSEVIER GMBH, URBAN & FISCHER VERLAG

Lugar: ALEMANIA; Año: 2016 vol. 37 p. 57 - 63

1125-7865

Soilerosion is a serious problem of land degradation in many parts of the world,and particularly in mountain rangelands. To understand this process it isnecessary to develop methods to assess soil erosion rates in a quick, economicand accurate manner. Based on the analysis of exposed Polylepis australis roots, we tested a dendrogeomorphologicalmethod for determining soil loss rate in rills and gullies. Few studies considerednon-coniferous tree rings in soil erosion analysis and we used, for the firsttime, an experimental procedure of root exposure and provided a comparison withroots exposed by gully erosion. Our main results showed that as aconsequence of soil erosion, exposed roots changed from root-like to a morestem-like wood anatomical structure. The percentage of vessel area pertree-ring area decreases by an average of 22% to 43% during the first andsecond year after exposure, respectively. Moreover, and during the same timeinterval, the mean vessel area decreased 32% and 65%, and the number of vesselsincreased 7% and 48%, respectively. Scars formed at the upper side of theexposed roots are coincident with changes in wood anatomy, and both evidencesmay be applied to reconstruct an erosion process. This study confirms that thewood anatomy analysis of partially exposed roots can be used to determine theyear in which roots are exposed and provides a useful tool to monitor soilerosion rates with a high accuracy.