UpWARD - Temperature and drought limitations on tree growth
| “We measure temperature and drought limitations on tree growth in alpine forests” |
Tree growth can be limited by both low temperatures and drought. While trees at higher elevations may benefit from rising temperatures, climate change is also increasing the intensity and frequency of drought events. Currently, it remains unclear how this affects alpine forests and at which elevation the main limitation of tree growth shifts from temperature to drought. UpWARD is tackling this question by establishing an innovative monitoring network in the Bavarian Alps. Along elevational gradients in Berchtesgaden National Park and around Garmisch-Partenkirchen, high-resolution point dendrometers continuously record stem diameter variations. Building on the WestWARD concept, all trees with a diameter at breast height of at least 15 cm are instrumented in each plot, thereby capturing ecosystem-level dynamics. Stem diameter variations include irreversible growth and reversible, water-related shrinking and swelling of the stem. Separating these signals allows us to quantify tree growth and to derive tree water deficit, the stem shrinkage caused by water loss, as a proxy for physiological drought stress. As part of the Center for Alpine Forest Management (subproject 2), UpWARD aims to improve our understanding of how climate change affects the growth and vitality of mountain and protective forests. Combined with meteorological and satellite remote sensing data from other subprojects, the newly implemented dendrometer network provides a basis for early-warning indicators and forest growth models. |
Example setups from the Berchtesgaden National Park and Garmisch-Partenkirchen research sites.