Reconstructing terrestrial nutrient cycling using stable nitrogen isotopes in wood

Gerhart, Laci; McLauchlan, Kendra K.

doi:10.1007/s10533-014-9988-8

Cited by 50 publications

(50 citation statements)

References 96 publications

(207 reference statements)

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“…Soil N isotopes integrate over longer time scales, e.g., centurial, and can include different processes than what control plant N isotope composition (Bustamante et al 2004). N isotopes are also a key to reconstructing past N availability, which helps us understand the current state and trajectory of N availability of ecosystems (Gerhart and McLauchlan 2014;McLauchlan et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

et al. 2015

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Background Knowledge of biological and climatic controls in terrestrial nitrogen (N) cycling within and across ecosystems is central to understanding global patterns of key ecosystem processes. The ratios of 15 N: 14 N in plants and soils have been used as indirect indices of N cycling parameters, yet our understanding of controls over N isotope ratios in plants and soils is still developing. Scope In this review, we provide background on the main processes that affect plant and soil N isotope ratios. In a similar manner to partitioning the roles of state factors and interactive controls in determining ecosystem traits, we review N isotopes patterns in plants and soils across a number of proximal factors that influence ecosystem properties as well as mechanisms that affect these patterns. Lastly, some remaining questions that would improve our understanding of N isotopes in terrestrial ecosystems are highlighted. Conclusion Compared to a decade ago, the global patterns of plant and soil N isotope ratios are more resolved. Additionally, we better understand how plant and soil N isotope ratios are affected by such factors as mycorrhizal fungi, climate, and microbial processing. A comprehensive understanding of the N cycle that ascribes different degrees of isotopic fractionation for each step under different conditions is closer to being realized, but a number of process-level questions still remain.

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Section: Introductionmentioning

confidence: 99%

Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

et al. 2015

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“…A robust set of breakpoint analyses identify the early 1920s as the time when a synchronous decline in wood δ 15 N values began. Declines in wood δ 15 N values toward present have been described in a number of studies and attributed to a variety of causes, described below (Gerhart and McLauchlan, 2014). Because of the synchrony of the breakpoint, the timing, and the direction of change (decline toward present), we believe the primary reason for the substantial decline in δ 15 N over the past century has been management practices within the state park, namely fire suppression that began in the late 1910s.…”

Section: Discussionmentioning

confidence: 85%

“…There are several alternative explanations for declining wood δ 15 N values that have been published in the literature (see Gerhart and McLauchlan, 2014, for a summary). Similar patterns of decline in wood δ 15 N observed elsewhere have been attributed to increases in atmospheric N deposition.…”

Section: Discussionmentioning

confidence: 99%

“…Given that humans have altered, and in many cases increased, the fluxes between major pools of elements, it is important to develop records that document the behavior of these cycles on various spatial scales prior to and following human disturbance. Fortunately, analysis of the standardized natural abundance ratios of 15 N to 14 N (δ 15 N) stored in tree rings is a relatively new technique that serves as a proxy record for the history of N availability in past terrestrial ecosystems (Gerhart and McLauchlan, 2014).…”

Section: Howard and K K Mclauchlan: Spatiotemporal Analysis Of Nmentioning

confidence: 99%

“…Although understanding how these factors affect the N cycle is of paramount importance to understanding recent changes in forest dynamics, long-term records of N cycling in forests are rare and generally restricted to modern measurements that might span a few decades at most (Gerhart and McLauchlan, 2014). Long-term monitoring of N cycling metrics such as stream nitrate export indicates an unexpected ability of many terrestrial ecosystems to retain added N, with stable or declining trends in N availability since monitoring began in the late 20th century (Bernal et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Spatiotemporal analysis of nitrogen cycling in a mixed coniferous forest of the northern United States

Howard

McLauchlan

2015

Biogeosciences

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Abstract. Nitrogen (N) is the limiting nutrient to primary productivity in a variety of temperate forests, and N cycling is undergoing a variety of anthropogenic changes, notably a doubling of reactive N (Nr) on a global scale. Yet, the magnitude of these changes to N cycling has been difficult to document in terrestrial ecosystems, especially in old-growth forests. To determine the trajectory of N cycling and the potential impacts of anthropogenic influences at local scales, we measured the composition of stable nitrogen isotopes (δ 15 N) in wood from living red pine trees (Pinus resinosa) at a single site in northern Minnesota, USA. A synchronous decline in wood δ 15 N values began approximately in the 1920s in 17 individual trees at different topographic positions, indicating a common driver. The decline in wood δ 15 N values corresponded with declines in sedimentary δ 15 N recorded in lacustrine sediments of the same catchment. Disturbance regime and species composition began to change at the turn of the 20th century with park establishment, providing a likely mechanism of decline in δ 15 N values toward present. While other mechanisms of this change are possible, we conclude that while there may be consequences of increased influxes of various forms of anthropogenic Nr into terrestrial ecosystems at the global level, these changes are not being expressed at a local level in this temperate forest ecosystem.

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Nitrogen Isotopes in Tree Rings—Challenges and Prospects

Savard

Siegwolf

2022

Tree Physiology

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Nutritive, but detrimental if at high levels, several nitrogen (N) forms involved in air and soil biogeochemical reactions constitute the N load trees assimilate. Although a large body of literature describes series of tree-ring N isotopes (δ15N) as archival systems for environmental changes, several questions relative to the isotopic integrity and reproducibility of trends still linger in the dendroisotopist community. This chapter reviews the fundamentals of forest N cycling and examines trees as N receptors in their very position, at the interface between the atmosphere and pedosphere. The related scrutiny of intrinsic and extrinsic mechanisms regulating isotopic changes also underlines flaws and forces of tree-ring δ15N series as environmental indicators.

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Reconstructing terrestrial nutrient cycling using stable nitrogen isotopes in wood

Cited by 50 publications

References 96 publications

Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

Spatiotemporal analysis of nitrogen cycling in a mixed coniferous forest of the northern United States

Nitrogen Isotopes in Tree Rings—Challenges and Prospects

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