Vegetation, soils, and forest productivity in selected forest types in interior Alaska

Abstract

Vegetation, forest productivity, and soils of 23 forest stands in the taiga of interior Alaska are described. The stands are arranged on an environmental gradient from an aspen (Populustremuloides Michx.) stand on a dry, steep south-facing bluff, to open black spruce (Piceamariana (Mill.) B.S.P.) stands underlain by permafrost on north-facing slopes. The coldest site is a mixed white spruce (Piceaglauca (Moench) Voss) and black spruce woodland at the treeline. Mesic upland sites are represented by successional stands of paper birch (Betulapapyrifera Marsh.) and aspen, and highly productive stands of white spruce. Several floodplain stands represent the successional sequence from productive balsam poplar (Populusbalsamifera L.) and white spruce to black spruce stands underlain by permafrost on the older terraces. The environmental gradient is described by using two soil factors: soil moisture and annual accumulated soil degree days (SDD), which range from 2217 SDD for the warmest aspen stand to 480 SDD for the coldest permafrost-dominated black spruce site. Soils vary from Alfie Cryochrepts on most of the mesic sites to Histic Pergelic Cryochrepts on the colder sites underlain by permafrost. A typical soil profile is described for each major forest type. A black spruce stand on permafrost has the lowest tree standing crop (15806 g•m−2) and annual productivity (56 g•m−2•year−1) whereas a mature white spruce stand has the largest tree standing crop (24 577 g•m−2) and an annual productivity of 540 g•m−2•year−1, but the successional balsam poplar stand on flood plain alluvium has the highest annual tree increment (952 g•m−2•year−1). The study supports the hypothesis that black spruce is a nutrient poor, unproductive forest type and that its low productivity is primarily the result of low soil temperature and high soil moisture.

Effects of competing vegetation on juvenile white spruce (Picea glauca (Moench) Voss) growth in Alaska

“…This area has some of the most productive white spruce stands in Alaska, with annual production averaging 366 g m -2 [36]. Soils are deep loess silt [32].…”

Towards improved parameterization of a macroscale hydrologic model in a discontinuous permafrost boreal forest ecosystem

“…A fine-resolution DEM is primarily used to parameterize the sub-grid heterogeneity of the landscape. In addition, the relationships between vegetation, permafrost, slope, and aspect (Viereck et al, 1983;Morrissey and Strong, 1986;Hinzman et al, 2006) are included in the sub-grid parameterization method.…”

“…In the Alaskan sub-arctic, vegetation type, density, physiological, and structural properties such as leaf area index (LAI) and stomatal conductance display a strong variation between permafrost-dominated and permafrost-free soils (Viereck et al, 1983;Viereck and Van Cleve, 1984). These variations can lead to significant variation in the partitioning of precipitation and snowmelt into runoff and evapotranspiration (ET), and change in soil water content between permafrost-dominated and permafrost-free soils Cable et al, 2014;Young-Robertson et al, 2016).…”

“…These variations can lead to significant variation in the partitioning of precipitation and snowmelt into runoff and evapotranspiration (ET), and change in soil water content between permafrost-dominated and permafrost-free soils Cable et al, 2014;Young-Robertson et al, 2016). Permafrost-affected soils typically support coniferous vegetation that is shallowly rooted, has low physiological activity, is tolerant of cold and wet soils, and is able to survive a short growing season (Viereck et al, 1983;Viereck and Van Cleve, 1984;Morrissey and Strong, 1986;Mölders, 2011). In contrast, the well-drained, relatively warm, permafrost-free soils support deciduous vegetation that is much larger, has higher LAI and stomatal conductance, and has a deeper rooting network (Cable et al, 2014;Young-Robertson et al, 2016).…”

Does overshoot in leaf development of ponderosa pine in wet years leads to bark beetle outbreaks on fine-textured soils in drier years?

“…In addition to climate conditions, soil characteristics such as water storage capacity, fertility and texture are well known to limit forest productivity (Viereck et al 1983;Powers et al 2005;Xu et al 2008;Puhlick et al 2012). Initial comparisons of forest mortality for all tree species in western Montana and soil characteristics were made by intersecting polygons in the Soil Survey Geographic database (SSURGO) soil data (NRCS 2014; min.…”