Carbon exchange in a hemiboreal mixed forest in relation to tree species composition

Old-growth forests are widely recognised for the benefits they provide for biodiversity; however, a more comprehensive understanding of their role in climate change mitigation must still be established to find the optimal balance between different forest ecosystem services at a national or regional scale. Very few studies have assessed carbon pools in old-growth Scots pine (Pinus sylvestris L.)-dominated boreal forests, and none have been conducted in hemiboreal forests. Therefore, we assessed the carbon storage of the living tree biomass, deadwood, forest floor (soil organic horizon, including all litter and decomposed wood), and mineral soil in 25 hemiboreal old-growth (163-218 years) unmanaged Scots pine stands in Latvia. The studied stands were without known records of any major natural or human-made disturbance in the visible past. Our results show, that the total ecosystem carbon pool (excluding ground vegetation) was 291.2 ± 54.2 Mg C ha −1 , which was primarily composed of living tree biomass (59%), followed by mineral soil (31%), deadwood (5%), and the forest floor (5%). Within the studied stand age group, the total carbon pool remained stable; however, interchanges among the carbon pools, i.e., living biomass and laying deadwood, did occur.

Section: Discussionsupporting

confidence: 89%

Carbon Pools in Old-Growth Scots Pine Stands in Hemiboreal Latvia

Ķēniņa

Jaunslaviete

Liepa

et al. 2019

“…Despite the short measurement period in our study, our results compare well with other similar locations. Krasnova et al [57] found annual results for NEE as −5.9 t C ha −1 yr −1 . Chi et al [58] found NEE was 5-8 t C ha −1 yr −1 (500-800 g C m -2 yr −1 ) six years after clear-cutting, similar to budget estimations in Aguilos et al [16] and Kolari et al [6] that found 12-year-old stand C budget is almost neutral.…”

Section: Discussionmentioning

confidence: 99%

Patterns of Carbon Sequestration in a Young Forest Ecosystem after Clear-Cutting

Rebane

Jõgiste

Kiviste

et al. 2020

A large area of Estonian hemiboreal forest is recovering from clear-cut harvesting and changing carbon (C) balance of the stands. However, there is a lack of information about C- source/sink relationships during recovery of such stands. The eddy covariance technique was used to estimate C-status through net ecosystem exchange (NEE) of CO2 in two stands of different development stages located in southeast Estonia in 2014. Measured summertime (June–September) mean CO2 concentration was 337.75 ppm with mean NEE −1.72 µmol m−2 s−1. June NEE was −4.60 µmol m−2 s−1; July, August, and September NEE was −1.17, −0.77, and −0.25 µmol m−2 s−1, respectively. The two stands had similar patterns of CO2 exchange; measurement period temperature drove NEE. Our results show that after clear-cutting a 6-year-old forest ecosystem was a light C-sink and 8-year-old young stand demonstrated a stronger C-sink status during the measurement period.

“…Mid-aged stands usually have higher CO 2 uptake rates [9]. Flux measurements taken from a mid-aged hemiboreal forest in Estonia in 2015 showed an annual NEE of −586 ± 45 gC•m −2 [63]. Grünwald and Bernhofer [64] reported an NEE in an old mixed spruce forest in Tharandt (Germany) of between −395 and −698 gC•m −2 .…”

Section: Ecosystem-atmosphere Co2 Exchange In the Spruce Forestsmentioning

confidence: 99%

Response of Spruce Forest Ecosystem CO2 Fluxes to Inter-Annual Climate Anomalies in the Southern Taiga

Mamkin

Varlagin

Yaseneva

et al. 2022

Climate extremes and anomalies modify the CO2 ecosystem–atmosphere exchange of the boreal forests and consequently alter the terrestrial carbon stocks and the atmospheric greenhouse gas concentrations. The effects of the anomalous weather conditions on the CO2 net ecosystem exchange (NEE), total ecosystem respiration (TER), and gross primary production (GPP) of the typical southern taiga nemorose spruce forest were analyzed using continuous eddy covariance flux measurements in the 2015–2020 period. The forest was found to be a source of atmospheric CO2 in 2016, 2017, 2019, and 2020 (the mean annual GPP/TER ratio was between 0.87 and 0.97). In 2018, the forest was found to act as a CO2 sink (GPP/TER = 1.47) when a positive temperature anomaly in the growing season was accompanied by a negative precipitation anomaly and increased global radiation. The early start of the CO2 uptake in the anomalously warm winter of 2019/2020 did not result in an increase in the annual GPP/TER ratio (0.90). The comparison of the flux data obtained from the nemorose spruce forest on the well-drained soils with the data obtained from paludified spruce forest in the same landscape showed that the mean annual GPP/TER ratio of the sites alternatively responded to the mentioned anomalies. This study suggests that a variety of soil moisture regimes across the southern taiga spruce forests provide a non-uniformity in the response reactions of the CO2 ecosystem–atmosphere exchange on the climate anomalies.