Treeline biogeochemistry and dynamics, Noatak National Preserve, northwestern Alaska

Stottlemyer, Robert; Binkley, Dan; Steltzer, Heidi

doi:10.3133/87282

Cited by 3 publications

(3 citation statements)

References 59 publications

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“…The treeline site is at the interface between tussock tundra (Shaver and Chapin 1991) and the forest. The soils are relatively poorly drained and underlain by discontinuous permafrost (Stottlemyer et al 2000). Stem density at the terrace, forest, and treeline sites is approximately 995, 1459, and 676 stems/ha, respectively.…”

Section: Site Descriptionsmentioning

confidence: 99%

Evidence of soil nutrient availability as the proximate constraint on growth of treeline trees in northwest Alaska

Sullivan

Ellison

McNown

et al. 2015

Ecology

113

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The position of the Arctic treeline, which is a key regulator of surface energy exchange and carbon cycling, is widely thought to be controlled by temperature. Here, we present evidence that soil nutrient availability, rather than temperature, may be the proximate control on growth of treeline trees at our study site in northwest Alaska. We examined constraints on growth and allocation of white spruce in three contrasting habitats. The habitats had similar aboveground climates, but soil temperature declined from the riverside terrace to the forest to the treeline. We identified six lines of evidence that conflict with the hypothesis of direct temperature control and/or point to the importance of soil nutrient availability. First, the magnitude of aboveground growth declined from the terrace to the forest to the treeline, along gradients of diminishing soil nitrogen (N) availability and needle N concentration. Second, peak rates of branch extension, main stem radial and fine-root growth were generally not coincident with seasonal air and soil temperature maxima. At the treeline, in particular, rates of aboveground and fine-root growth declined well before air and soil temperatures reached their seasonal peaks. Third, in contrast with the hypothesis of temperature-limited growth, growing season average net photosynthesis was positively related to the sum of normalized branch extension, main stem radial and fine-root growth across trees and sites. Fourth, needle nonstructural carbohydrate concentration was significantly higher on the terrace, where growth was greatest. Fifth, annual branch extension growth was positively related to snow depth, consistent with the hypothesis that deeper snow promotes microbial activity and greater soil nutrient availability. Finally, the tree ring record revealed a large growth increase during late 20th-century climate warming on the terrace, where soil N availability is relatively high. Meanwhile, trees in the forest and at the treeline showed progressively smaller growth increases. Our results suggest temperature effects on tree growth at our study sites may be mediated by soil nutrient availability, making responses to climate change more complex and our ability to interpret the tree ring record more challenging than previously thought.

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Section: Site Descriptionsmentioning

confidence: 99%

Evidence of soil nutrient availability as the proximate constraint on growth of treeline trees in northwest Alaska

Sullivan

Ellison

McNown

et al. 2015

Ecology

113

View full text Add to dashboard Cite

show abstract

“…The treeline site is at the interface between tussock tundra (Shaver & Chapin 1991) and the forest. The soils are relatively poorly drained and underlain by discontinuous permafrost (Stottlemyer, Binkley & Steltzer 2000). The understory is dominated by Eriophorum vaginatum tussocks.…”

Section: S I T E D E S C R I P T I O N Smentioning

confidence: 99%

Low photosynthesis of treeline white spruce is associated with limited soil nitrogen availability in the Western Brooks Range, Alaska

McNown

Sullivan

2013

Functional Ecology

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Summary1. The prevailing hypothesis states that treeline positions are defined by the direct effects of cold temperatures on cell division and tree growth. Meanwhile, photosynthesis is thought to be relatively unrestricted in treeline trees. Support for this hypothesis comes from the global correlation between temperature and treeline position, the observation that many treelines have advanced in response to recent warming and the frequent use of increment cores from treeline trees to reconstruct past climates. However, studies of the physiology of trees at the Arctic treeline are rare, and this hypothesis remains largely untested. 2. To improve our understanding of the relationships between temperature and performance of white spruce near the Arctic treeline, we made measurements of needle gas exchange, needle nutrition and soil nutrient availability over 2 years in three contrasting habitats: riverside terrace, hillslope forest and treeline. The sites had similar above-ground microclimates, but very different soil conditions. Soils were warm and dry on the terrace, cool and moist in the forest and cold and seasonally wet the treeline. 3. Photosynthesis, needle nitrogen (N) concentration and soil N availability declined from the terrace to the forest to the treeline. Low N availability at the treeline was likely a consequence of limited microbial activity in the cold and seasonally wet soils. Soils at the treeline were colder than the terrace during the growing season and colder than the forest in winter, when the treeline maintains a shallow snowpack. 4. Our results highlight the potential for an indirect effect of temperature on the growth of trees at the Arctic treeline and suggest that treeline responses to changes in climate may be more complex than previously thought.

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“…It was unexpected that NO 3 - and P were statistically higher in logged forest than primary forest as it was thought that the more open canopy of logged forest would cause more surface erosion or leaching of salts. This could also indicate that conditions for mineralisation are greater in logged forest soils possibly due to better drainage (Stottlemyer et al 2001) and higher temperatures (Miller and Geisseler 2018), and the litter fall from the pioneering trees could be easier for microbes to break down (Quan et al 2014). Since logged forest soils have a southeastern slope and a more open canopy, these attributes may have better drainage and higher temperatures and, hence, caused greater mineralisation.…”

Section: Discussionmentioning

confidence: 99%

Changes in soil chemical properties and their spatial distribution after logging and conversion to oil palm plantation in Sabah (Borneo)

Flynn,

Tuma,

Fayle

et al. 2023

J. Trop. Ecol.

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Conversion of primary forest into oil palm plantations is common in tropical countries, affecting soil properties, ecosystem services and land-use management. However, little is known about the short-range spatial soil distribution that is important for soil scientists, ecologists, entomologists, mycologists or microbiologists. In this study, seven soil properties (pH, EC (µS/m), P (mg/kg), NO3- (mg/kg), N%, C% and C:N) were measured to quantify the spatial autocorrelation across primary forest, selectively logged forest and oil palm plantation in Sabah, Malaysian Borneo. Local variograms were calculated (range ∼5 m) to determine the short-range variation, and a decision tree as well as principal component analysis were implemented to determine if the overall (global) mean differed between land uses. As hypothesised, oil palm soils deviated the most from primary forest soils, which had more fluctuating variograms and in general, a shorter range. Oil palm plantations also showed a difference in the global mean except for electrical conductivity. Selectively logged forests also differed in their short-range spatial structure; however, the global mean and variance remained similar to primary forest soil with the exception of labile phosphorus and nitrate. These results were attributed to initial plantation development, removal of topsoil, fertiliser application and topography.

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Treeline biogeochemistry and dynamics, Noatak National Preserve, northwestern Alaska

Cited by 3 publications

References 59 publications

Evidence of soil nutrient availability as the proximate constraint on growth of treeline trees in northwest Alaska

Evidence of soil nutrient availability as the proximate constraint on growth of treeline trees in northwest Alaska

Low photosynthesis of treeline white spruce is associated with limited soil nitrogen availability in the Western Brooks Range, Alaska

Changes in soil chemical properties and their spatial distribution after logging and conversion to oil palm plantation in Sabah (Borneo)

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