Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Malik I.

2 2006

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: exposed roots

Sortuj według:

Ogranicz wyniki do:

Erozja wąwozowa zapisana w odsłanianych korzeniach drzew na Wysoczyźnie Proboszczowickiej pod Górą Św. Anny

Malik I.

Przegląd Geologiczny

2006

Vol. 54, nr 4

326-332

Erosion occurs in permanent gullies cutting into the undulating loess plateau in southern Poland. The gully slopes are mainly vegetated with beech trees as opposed to the surface of the plateau summit, which is cultivated agricultural land, devoid of forests for at least 18 centuries [od 18 wieków czy od XVIII wieku – czyli “since 1700s”?]. Beech roots are exposed in the gullies through erosion. Wood cells in the tree rings divide into early wood and late wood and, after the roots are exposed, also start to make fewer cells. In the roots on the border between exposed and unexposed tree rings in the tree roots, scars sometimes occur. This is an effect produced by corrasion by dolomites and limestones lying under the loess cover and re-deposition of building material stored by people in the higher part of the gullies. These anatomical changes in root tree rings allow one to date erosion episodes. Dating of the exposure of roots indicates that intensive erosion took place in the gullies starting in the 1980s. Since that time, numerous extreme rainfall events responsible for initiating erosion have also occurred. They contribute to deepening valleys causing new incisions to develop on hillslopes and headcut retreat in upper parts of the valleys studied at theWysoczyna Proboszczowicka near Góra św. Anny. The bottom of the valley head eroded during extreme rainfall events in 1984 and 1991. Erosion here alternates with deposition, its speed being relatively small. Incisions in hill slopes retreated during the flood in 1997, but they originated during earlier rainfall episodes. Such incisions retreat 2.5–3 m/year, i.e., relatively fast.

Gully erosion dating by means of anatomical changes in exposed roots (Proboszczowicka Plateau, Southern Poland)

Malik I.

Geochronometria

2006

Vol. 25

57-66

Re-incision occurs in gullies in the undulating loess plateau in southern Poland. The gully hillslopes are mainly covered with beech trees. The beech roots are exposed in the gullies through erosion. The wood cells in the root tree rings divide into early wood and late wood, and after the roots are exposed, they start to make fewer cells. Dolomites and limestones lying under the loess cover are transported and wound the tree roots. As a result of this process on the border between exposed and unexposed tree rings in the tree roots, scars sometimes occur. These anatomical changes in root tree rings allow to date erosion episodes with one year accuracy. Dating of the exposure of roots indicates that intensive gully erosion in the studied gully started in the 1970s. Since that time, numerous extreme rainfall events responsible for initiating erosion have also occurred. The bottom of the valley head eroded during extreme rainfall events in 1984 and 1991. Erosion here alternates with deposition, its rate being relatively small. Incisions in hillslopes retreated during the flood in 1997, but they originated during earlier rainfall episodes. Hillslope undercutting occurring in the lower part of the gully was formed during older erosion episodes in 1971 and 1984.