Drought Adaptation of the Fine Root System and Hydraulic Architecture of Larix sibirica at its Southern Distribution Limit General introduction

• Main Author: Chenlemuge, Tselmeg
• Other Authors: Hauck, Markus Prof. Dr., Leuschner, Christoph Prof. Dr., Gansert, Dirk PD Dr.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2015
• Subjects: 570; Drought; forest-steppe ecotone; root dieback; Hydraulic conductivity; Wood anatomy; Drought adaptation; Larix sibirica; Mongolia; Biologie (PPN619462639); taiga
• Online Access: http://hdl.handle.net/11858/00-1735-0000-0023-9980-9; https://doi.org/10.53846/goediss-4857; https://nbn-resolving.org/urn:nbn:de:gbv:7-11858/00-1735-0000-0023-9980-9-0

Taiga-steppe ecotone is a natural grassland habitat with isolated forest islands and low precipitation (c. 100-250 mm yr-1), and is an important part of the boreal biome. The southernmost distribution limit of Siberian taiga occurs in the mountainous areas of Northern and Western Mongolia. In these areas, larch (Larix sibirica) forest patches are normally restricted to the upper part of humid north-facing slopes, whereas steppe covers south-facing slopes and most valley bottoms. Temperatures have been rising faster here than the the global average for decades, but precipitation has not increased concomitantly. Induced by the increasing aridity, a decades-long decline in the growth and regeneration of the larch forests, and differentiation in the growth performance of L. sibirica between within-stand microhabitats (forest edge vs. forest interior) was evidenced by earlier work. However, the physiological mechanisms underlying these ecological responses to drought stress and climate warming are not fully understood. As a contribution to answer these questions, bio- and necromass and morphological properties of fine roots, xylem hydraulic conductivity and wood anatomical properties along the flow pass (root, stem, and branch) together with tree productivity in monospecific L. sibirica stands were studied in this thesis. The study was conducted in two dry sites (the Altai and the Khangai Mountains) in the Mongolian forest-steppe ecotone and a moist site in Central Europe (the Ore Mts. in Germany). The dry sites contain natural L. sibirica stands while the moist site is a L. sibirica plantation outside its natural range. Field work was carried out during three continuous growing seasons (July/August 2010, 2011 and 2012) which started with two dry years (2010–2011) and a subsequent wet year (2012). Variations in fine root mass and morphological properties between the dry and moist years and between the dry and moist site were examined. Spatial distribution of fine roots was also investigated in the Mongolian Altai. ...