A Deciduous Forest’s CO2 Exchange Within the Mixed-Humid Climate of Kentucky, USA
Abstract
:1. Introduction
2. Materials and Methods
3. Results
3.1. Weather and Climate
3.2. Ecosystem Carbon Dioxide Fluxes
3.3. Cumulative Ecosystem Exchange
3.4. Seasonal Distribution of Gross Primary Productivity (GPP), Ecosystem Respiration (RE), and Net Ecosystem Exchange (NEE)
3.5. Diurnal Pattern of Gross Primary Productivity (GPP), Ecosystem Respiration (RE), and Net Ecosystem Exchange (NEE)
3.6. Environmental Control of Carbon Dioxide Exchange
3.6.1. Monthly Light Response Curves (Michelis–Menten Curves)
3.6.2. Monthly Temperature Response Curves for the Year 2016
3.6.3. Correlational Analysis
3.6.4. Seasonal Regression (Four Seasons)
4. Discussion
4.1. Ecosystem Scale Exchanges
4.2. Controlling Variables
5. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
NEE | Net Ecosystem Exchange |
GPP | Gross Primary Productivity |
RE | Ecosystem Respiration |
References
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χ2 | df | p | ε2 | |
---|---|---|---|---|
NEE | 6766 | 3 | <0.001 | 0.0863 |
RE | 33,970 | 3 | <0.001 | 0.4332 |
GPP | 22,488 | 3 | <0.001 | 0.2868 |
Year | NEE | RE | GPP | RE/GPP | Status |
---|---|---|---|---|---|
2016 | −403 | 1353 | 1756 | 0.771 | Sink |
2017 | −364 | 1429 | 1793 | 0.797 | Sink |
2018 | −144 | 1259 | 1403 | 0.897 | Sink |
2019 | −254 | 1617 | 1871 | 0.864 | Sink |
2020 | −350 | 1212 | 1562 | 0.776 | Sink |
Total (Mean) | −1515 (−303) | 6870 (1374) | 8385 (1677) | Sink |
Month | Amax | α | Re (gCm−2) | Total NEE (gCm−2) | Mean NEE (gCm−2) | Mean PPFD (µMol/m2) | n | R2 (%) |
---|---|---|---|---|---|---|---|---|
January | 0.000 | 0.627 | 0.017 | 8.812 | 0.017 | 494.87 | 509 | 0.00 |
February | 0.000 | 0.588 | 0.002 | 1.341 | 0.002 | 505.95 | 556 | 0.00 |
March | 0.000 | 0.744 | 0.025 | 16.672 | 0.025 | 680.87 | 677 | 43.01 |
April | 1.511 | 0.617 | 1.507 | 4.093 | 0.006 | 839.59 | 726 | 38.18 |
May | 0.583 | 0.001 | 0.044 | −169.581 | −0.213 | 792.08 | 796 | 87.29 |
June | 2.656 | 1.386 | 3.431 | −175.644 | −0.216 | 986.26 | 814 | 45.07 |
July | 3.205 | 1.304 | 2.947 | −191.990 | −0.234 | 865.02 | 822 | 39.21 |
August | 1.736 | 0.676 | 1.548 | −134.826 | −0.174 | 816.94 | 776 | 39.50 |
September | 1.246 | 0.699 | 1.106 | −91.443 | −0.134 | 859.99 | 682 | 44.73 |
October | 0.222 | 1.769 | 0.175 | −30.087 | −0.047 | 693.53 | 639 | 46.59 |
November | 0.672 | 1.286 | 0.691 | 10.995 | 0.020 | 557.66 | 542 | 45.81 |
December | 0.000 | 0.572 | 0.018 | 8.943 | 0.018 | 380.27 | 498 | 49.87 |
β0 | β1 | Q10 raw data | Q10 modeled | Total RE (gCm−2) | Mean RE (gCm−2) | Mean Tair (°C) | R2 (%) | n | |
---|---|---|---|---|---|---|---|---|---|
Jan | 0.010 | 0.060 | 2.296 | 1.825 | 8.837 | 0.009 | −2.06 | 92.67 | 977 |
Feb | 0.011 | 0.010 | 1.914 | 1.108 | 8.110 | 0.010 | 2.71 | 99.82 | 836 |
Mar | 0.010 | 0.039 | 1.513 | 1.475 | 12.313 | 0.015 | 8.49 | 98.05 | 811 |
Apr | 0.018 | 0.073 | 3.083 | 2.083 | 30.468 | 0.043 | 10.81 | 91.90 | 714 |
May | 0.056 | 0.034 | 1.474 | 1.410 | 62.458 | 0.090 | 13.54 | 99.31 | 693 |
Jun | 0.026 | 0.061 | 1.766 | 1.834 | 53.504 | 0.085 | 19.14 | 97.12 | 626 |
Jul | 0.048 | 0.064 | 2.223 | 1.895 | 126.243 | 0.190 | 21.43 | 94.10 | 666 |
Aug | 0.037 | 0.066 | 2.121 | 1.944 | 111.418 | 0.156 | 21.75 | 98.80 | 712 |
Sep | 0.052 | 0.044 | 1.598 | 1.556 | 86.482 | 0.114 | 17.53 | 98.74 | 758 |
Oct | 0.051 | 0.037 | 1.665 | 1.447 | 69.696 | 0.082 | 12.47 | 98.57 | 849 |
Nov | 0.019 | 0.060 | 1.799 | 1.817 | 26.964 | 0.030 | 6.22 | 95.23 | 898 |
Dec | 0.014 | 0.037 | 2.190 | 1.445 | 16.092 | 0.016 | 2.77 | 97.35 | 990 |
Q10 modeled | Total RE (gCm−2) | Mean RE (gCm−2) | Mean Tair (°C) | Total GPP | Mean GPP | n | |
---|---|---|---|---|---|---|---|
2016 | 2.697 | 612.57 | 0.064 | 10.30 | 1483.40 | 0.185 | 9530 |
2017 | 1.881 | 674.82 | 0.071 | 10.67 | 1416.17 | 0.176 | 9473 |
2018 | 2.002 | 620.09 | 0.092 | 10.19 | 1212.59 | 0.226 | 6770 |
2019 | 1.992 | 774.86 | 0.081 | 16.94 | 1592.45 | 0.199 | 9519 |
2020 | 2.046 | 533.33 | 0.073 | 16.12 | 921.51 | 0.185 | 7267 |
NEE | RE | GPP | |
---|---|---|---|
LE | −0.58 ** | 0.32 ** | 0.61 ** |
VPD | −0.16 ** | 0.19 ** | 0.21 ** |
Tair | −0.30 ** | 0.60 ** | 0.48 ** |
ET | −0.48 ** | 0.24 ** | 0.50 ** |
PPFD | −0.39 ** | 0.25 ** | 0.42 ** |
H | −0.22 ** | 0.00 | 0.19 ** |
Season | NEE | Reco | GPP | |
---|---|---|---|---|
(a) winter | LE | 0.19 ** | 0.02 ** | −0.19 ** |
VPD | 0.06 ** | 0.24 ** | −0.01 | |
Tair | 0.04 ** | 0.49 ** | 0.06 ** | |
ET | 0.27 ** | 0.03 ** | −0.26 ** | |
PPFD | −0.08 ** | 0.09 ** | 0.10 ** | |
H | −0.01 | −0.01 | 0.01 | |
(b) spring | LE | −0.51 ** | 0.35 ** | 0.55 ** |
VPD | −0.06 ** | 0.22 ** | 0.13 ** | |
Tair | −0.21 ** | 0.57 ** | 0.36 ** | |
ET | −0.38 ** | 0.27 ** | 0.42 ** | |
PPFD | −0.29 ** | 0.19 ** | 0.31 ** | |
H | −0.20 ** | −0.01 | 0.17 ** | |
(c) summer | LE | −0.67 ** | 0.08 ** | 0.65 ** |
VPD | −0.25 ** | 0.16 ** | 0.29 ** | |
Tair | −0.28 ** | 0.23 ** | 0.34 ** | |
ET | −0.59 ** | 0.07 ** | 0.58 ** | |
PPFD | −0.43 ** | 0.12 ** | 0.45 ** | |
H | −0.58 ** | 0.06 ** | 0.57 ** | |
(d) fall | LE | −0.47 ** | 0.21 ** | 0.49 ** |
VPD | −0.30 ** | 0.12 ** | 0.30 ** | |
Tair | −0.28 ** | 0.45 ** | 0.44 ** | |
ET | −0.41 ** | 0.16 ** | 0.42 ** | |
PPFD | −0.37 ** | 0.17 ** | 0.39 ** | |
H | −0.24 ** | −0.01 | 0.20 ** |
Country | Forest Type | NEE (g C yr−1) | GPP (g C yr−1) | RE (g C yr−1) | Study Years | Location | Reference |
---|---|---|---|---|---|---|---|
USA | Mostly Deciduous | −303 | 1535 | 1374 | 2016–2020 | 37°8′17.16″ N, 83°34′46.82″ W | This study |
“ | Deciduous broadleaf | −250 | 1400 | 1150 | - | 42°32′24″ N, 72°10′12″ W | [40] |
“ | Mixed deciduous | −198 | 1297 | 1099 | 1993–2000 | 42.5 N, 72.2 W | [35] |
“ | “ | −247 | 1400 | 1153 | 1992–2004 | 42.538 N, 72.171 W | [40] |
Canada | Mixed deciduous & coniferous | −142 | 1118 | 976 | 1996–2003 | 44°19′ N, 79°56′ W | [39] |
Brazil | Dry tropical | −168.7 | 414.7 | 246 | 2014 | 6°34′42″ S, 37°15′05″ W | [11] |
“ | “ | −145 | 334 | 189 | 2015 | “ | “ |
Iceland | Managed deciduous broadleaf | −100 | 710 | 610 | - | 63°49′48″ N, 20°13′12″ W | [63] |
Denmark | “ | −150 | 1190 | 1040 | - | 55°28′48″ N, 11°38′24″ E | “ |
UK | Deciduous | −130 | 2110 | 1980 | 2007–2009 | 51°46′12″ N, 1°19′48″ W | [71] |
“ | Deciduous broadleaf | −486 | 2034 | 1548 | 1999–2010 | 51°07′12″ N, 0°51′00″ W | [72] |
Germany | Deciduous broadleaf | −490 | 1560 | 1070 | - | 51°04′12″ N, 10°27′00″ E | [60] |
Italy | Deciduous broadleaf | −660 | 1300 | 640 | - | 41°52′12″ N, 13°35′24″ E | [63] |
Denmark | European beech | −157 | 1727 | 1570 | 1996–2009 | 55°29′13′′ N, 11°38′45′′ E | [73] |
Japan | Deciduous broadleaf | −261 | 1118 | 857 | 2000 | 42°58′48″ N, 141°22′48″ E | [74] |
“ | “ | −258 | - | - | 1999–2001 | 42°40′12″ N, 141°36′00″ E | [75] |
“ | “ | −207 | 948 | 741 | - | 36°07′48″ N, 137°25′12″ E | [76] |
“ | “ | −357 | - | - | 1997 | 35°52′12″ N, 139°28′48″ E | [77] |
“ | Deciduous | −236 | 978 | 742 | 1994–2002 | 36°08′ N, 137°25′ E | [78] |
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Familusi, I.; Gebremedhin, M.; Gyawali, B.; Chiluwal, A.; Brotzge, J. A Deciduous Forest’s CO2 Exchange Within the Mixed-Humid Climate of Kentucky, USA. Forests 2025, 16, 562. https://doi.org/10.3390/f16040562
Familusi I, Gebremedhin M, Gyawali B, Chiluwal A, Brotzge J. A Deciduous Forest’s CO2 Exchange Within the Mixed-Humid Climate of Kentucky, USA. Forests. 2025; 16(4):562. https://doi.org/10.3390/f16040562
Chicago/Turabian StyleFamilusi, Ife, Maheteme Gebremedhin, Buddhi Gyawali, Anuj Chiluwal, and Jerald Brotzge. 2025. "A Deciduous Forest’s CO2 Exchange Within the Mixed-Humid Climate of Kentucky, USA" Forests 16, no. 4: 562. https://doi.org/10.3390/f16040562
APA StyleFamilusi, I., Gebremedhin, M., Gyawali, B., Chiluwal, A., & Brotzge, J. (2025). A Deciduous Forest’s CO2 Exchange Within the Mixed-Humid Climate of Kentucky, USA. Forests, 16(4), 562. https://doi.org/10.3390/f16040562