Seasonality and nitrogen supply modify carbon partitioning in understory vegetation of a boreal coniferous forest
(2016) In Ecology 97(3). p.671-683- Abstract
Given the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ 13CO2 pulse-labeling technique to examine the short-term dynamics of C partitioning in understory vegetation in three boreal Pinus... (More)
Given the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ 13CO2 pulse-labeling technique to examine the short-term dynamics of C partitioning in understory vegetation in three boreal Pinus sylvestris forest stands exposed to different rates of N addition: a low and high N addition that receive annual additions of NH4NO3 of 20 and 100 kg N/ha, respectively, and this is a typo. It should be an unfertilized control. Labeling was conducted at two distinct periods (early vs. late growing season), which provided a seasonal picture of how N addition affects C dynamics in understory vegetation. In contrast to what has been found in trees, there was no obvious trend in belowground C partitioning in ericaceous plants in response to N additions or seasonality. Increasing N addition led to a greater percentage of 13C being incorporated into ericaceous leaves with a high turnover, whereas high rates of N addition strongly reduced the incorporation of 13C into less degradable moss tissues. Addition of N also resulted in a greater percentage of the 13C label being respired back to the atmosphere and an overall reduction in total understory carbon use efficiency. Taken together, our results suggest a faster cycling of C in understory vegetation with increasing N additions; yet the magnitude of this general response was strongly dependent on the amount of N added and varied seasonally. These results provide some of the first in situ C and N partitioning estimates for plants growing under the complex web of resource limitations in the boreal understory.
(Less)
- author
- Hasselquist, N. J. ; Metcalfe, D. B. LU ; Marshall, J. D. ; Lucas, R. W. and Högberg, P.
- organization
- publishing date
- 2016-03-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- C, Biomass allocation, Boreal forest, Carbon cycling, Ericaceous shrubs, Isotopes, Mosses, Nitrogen availability, Pulse-chase labeling, Seasonality
- in
- Ecology
- volume
- 97
- issue
- 3
- pages
- 13 pages
- publisher
- Ecological Society of America
- external identifiers
-
- pmid:27197394
- scopus:84962129343
- ISSN
- 0012-9658
- language
- English
- LU publication?
- yes
- id
- e2bd2829-c486-487b-844d-d935259c661e
- date added to LUP
- 2016-07-14 10:38:32
- date last changed
- 2025-01-12 08:53:46
@article{e2bd2829-c486-487b-844d-d935259c661e,
abstract = {{<p>Given the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ <sup>13</sup>CO<sub>2</sub> pulse-labeling technique to examine the short-term dynamics of C partitioning in understory vegetation in three boreal Pinus sylvestris forest stands exposed to different rates of N addition: a low and high N addition that receive annual additions of NH<sub>4</sub>NO<sub>3</sub> of 20 and 100 kg N/ha, respectively, and this is a typo. It should be an unfertilized control. Labeling was conducted at two distinct periods (early vs. late growing season), which provided a seasonal picture of how N addition affects C dynamics in understory vegetation. In contrast to what has been found in trees, there was no obvious trend in belowground C partitioning in ericaceous plants in response to N additions or seasonality. Increasing N addition led to a greater percentage of <sup>13</sup>C being incorporated into ericaceous leaves with a high turnover, whereas high rates of N addition strongly reduced the incorporation of <sup>13</sup>C into less degradable moss tissues. Addition of N also resulted in a greater percentage of the <sup>13</sup>C label being respired back to the atmosphere and an overall reduction in total understory carbon use efficiency. Taken together, our results suggest a faster cycling of C in understory vegetation with increasing N additions; yet the magnitude of this general response was strongly dependent on the amount of N added and varied seasonally. These results provide some of the first in situ C and N partitioning estimates for plants growing under the complex web of resource limitations in the boreal understory.</p>}},
author = {{Hasselquist, N. J. and Metcalfe, D. B. and Marshall, J. D. and Lucas, R. W. and Högberg, P.}},
issn = {{0012-9658}},
keywords = {{C; Biomass allocation; Boreal forest; Carbon cycling; Ericaceous shrubs; Isotopes; Mosses; Nitrogen availability; Pulse-chase labeling; Seasonality}},
language = {{eng}},
month = {{03}},
number = {{3}},
pages = {{671--683}},
publisher = {{Ecological Society of America}},
series = {{Ecology}},
title = {{Seasonality and nitrogen supply modify carbon partitioning in understory vegetation of a boreal coniferous forest}},
volume = {{97}},
year = {{2016}},
}