Tree-limit rise and recent warming: a geoecological case study from the Swedish Scandes

Abstract

Tree-limit rise and recent warming: a geoecological case study from the Swedish Scandes LEIF KULLMAN Kullman, L. 2000. Tree-limit rise and recent warming: a geoecological case study from the Swedish Scandes.Twentieth-century elevational tree-limit (TL) and species-limit histories have been reconstructed for Pinus sylvestris, Picea abies and Betula pubescens ssp. tortuosa within a permanent belt transect in the southern Swedish Scandes. Upward TL shifts of 100-130 m between c. 1915 and 1999 appear related to a summer warming of c. 0.78C, and increased winter temperatures. Rates of tree recruitment and individual growth have increased substantially since 1974, notably during the 1990s, apparently mainly in response to some warm summers and a sequence of exceptionally mild winters. The distributional trend during the 20th century constitutes a fundamental and unexpected break in a monotonic, century-scale TL descent throughout most of the Holocene (exemplified by Pinus sylvestris), which was particularly accentuated during the 'Little Ice Age' of the past several centuries. Assuming that the TL stabilizes at the new, higher level for several decades, its elevation will be higher than at any time during at least the past c. 4000 radiocarbon years. This recent history is relevant as one possible model of the ecological consequences of anthropogenic climate forcing, and the TL may be an appropriate and sensitive system for monitoring the ecological effects of future climate change and variability.

Impacts of Climate Change on Vegetation Distribution No. 1 -- Climate Change Induced Vegetation Shifts in the Palearctic Region

“…Based on these observations, range-margin rise and invasion into alpine tundra communities, high above the current tree-limits, are foreseen for many tree and shrub species. This is supported by the tree-limit and range-margin rise amounting to 100-150 m identified over the past century more generally in the study region (Kullman, 2000a(Kullman, , 2001). Kullman (2006) assumes that many plants adjust their altitudinal ranges to new climatic regimes much faster than generally assumed, however, plants have migrated upslope with widely different rates.…”

“…In northern Scandinavia, temperatures now may be higher than at any time in the past 4000-5000 years (Kullman & Kjallgren, 2000;Kullman 2000a). A general trend of summer warming could be observed and winters have been consistently milder (Kullman, 2002).…”

The Forest Ecotone Effect on Species Richness in an Arid Trans-Himalayan Landscape of Nepal

“…A major ecotone is the compositional change from sub-alpine forest to open alpine vegetation. The forest-line ecotone is a major concern in ecological studies due to its sensitivity to climate and land-use changes (Hofgaard 1997;Kullman 1998Kullman , 2000Körner 1999). Some species have their distribution more-or-less restricted to above, or below, the forest limit (Hofgaard and Willmann 2002), but many species range across the regional forest line.…”

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

“…While several studies have reported accelerated height growth of previously low-growing tree individuals from different treeline ecotones (e.g. Lescop-Sinclair and Payette, 1995;Kullman, 2000;Kullman and Öberg, 2009), no such information from Himalayan treelines is available to date. However, it can be inferred from remote-sensingbased studies that the expansion of treeline ecotones, subalpine forests, and alpine scrub in recent decades is accompanied by enhanced height growth of individual trees.…”