Stand structure, invasion, and growth dynamics of bog pine (Pinus uncinata var. rotundata) in relation to peat cutting and drainage in the Jura Mountains, Switzerland

Abstract

A description of bog pine stands (Pinus uncinata Ramond var. rotundata (Link) Antoine) on uncut oligotrophic mires affected by drainage and nearby peat cuttings at three sites of the Jura Mountains (Switzerland) is given. In all sites, three situations were chosen: (i) central parts of the bogs, (ii) surfaces near cutting walls and bog margins, and (iii) intermediate situations. Population structures were characteristic for each situation. In the open and wet central parts of the bogs, trees were scattered, small, and uneven aged. In the intermediate situations, tree density was higher, and the stand was multilayered with taller and uneven-aged individuals. Near the edges of the bogs or close to the peat cutting walls, the trees were tall, even-aged, and younger with a high growth rate. The nonsynchronous colonization of the bog pine trees on the three sites indicates that local factors such as drainage and peat cuttings in the vicinity of the uncut surfaces were more influential than climate factors. Radial growth patterns, very similar between the sites and the various pinewood stands, and the numerous common pointer years reflect local and regional climate fluctuations. The pinewood development on uncut bogs in the Jura Mountains thus represents a recent dynamics, which is strongly linked to human activities.

Spatio-temporal pattern of bog pine (Pinus uncinatavar.rotundata) at the interface with the Norway spruce (Picea abies) belt on the edge of a raised bog in the Jura Mountains, Switzerland

“…Thus, the pinewood development on a large scale in the Jura bogs may represent a recent phenomenon. Extension of tall pinewood stands has been observed after the Jura bogs were affected by drainage [17]. This is confirmed by Hubschmid and Lang [23], Joray [25] and Reille [38], who emphasized that there has been a drastic increase in pine pollen abundance in the recent past within peat profiles, although pine (Pinus spp.)…”

“…latewood event years, which permit good cross-dating between bog pines. (2) Increase or decrease event years based on abrupt growth changes can be used as high frequency signals which may be interpreted in relation to climate, to human disturbances such as drainage [17], to unfavourable hydrologic conditions (this issue), or to take in evidence tree stand succession [19]. (3) Abrupt growth change curves maximise medium-term fluctuations, so that high-frequency signals are suppressed.…”

“…One or two radii per tree served to establish the AGCm curve. Further details are available in Freléchoux et al [17].…”

“…Most of the bogs in Switzerland have been drained and cut mainly between the 18th and the middle of the 20th century. Drainage of peat bogs can trigger bog pine invasion and affect the structure of tree populations and tree growth [16,17]. Vegetation changes on uncut surfaces have often occurred as an indirect result of peat cutting in the vicinity [16,18].…”

The Essential Role of the Lagg in Raised Bog Function and Restoration: A Review

“…In terms of tree density, Freléchoux et al (2000) observed a low density of small pine trees in the central, wetter parts of bogs, compared to a higher density of taller pines in the drier rand of the bog. Bubier (1991) found similar results for Picea mariana (black spruce) for a raised bog in Vermont.…”