Environmental controls over calcium and magnesium concentrations in the forest floor and topsoil in the Loess Plateau, China

Abstract

The dynamics of calcium (Ca) and magnesium (Mg) in the forest floor and topsoil caused by anthropogenic and natural processes continue to be a concern in temperate forests. However, the impacts of abiotic and biotic variables as well as their interactions remain unclear, especially in areas undergoing long-term forest restoration. In this study, Ca and Mg concentrations in the forest floor and topsoil from 239 forest plots across the Loess Plateau were measured, and the effects of forest types, climate, soil properties, stand characteristics and nitrogen deposition were explored. The results showed significantly higher Ca concentrations in the forest floor (20.68 ± 8.04 mg/g) than in the topsoil (13.28 ± 12.83 mg/g), whereas Mg exhibited the inverse pattern (3.64 ± 1.09 and 10.11 ± 2.51 mg/g, respectively). The effect of forest types was only significant on forest floor Ca, and Ca concentrations were higher in broadleaf and mixed forests than in coniferous forests. Overall, Ca and Mg concentrations in forest floor and topsoil increased with latitudes while decreased with elevations, and the significance of the trends varied among forest types. Forest floor Ca and Mg were mainly influenced by environmental variables aboveground, i.e., basal area (BA) and mean annual precipitation (MAP), respectively; topsoil Ca and Mg were more affected by soil properties (soil C/N and pH, respectively). Those suggested a depletion of Ca belowground was associated with forest growth and enriched soil nitrogen, and the leaching of mobile Mg was correlated with rainfall and soil acidification. Besides, the impact of environmental variables on Ca-Mg balance (Ca/Mg ratio) belowground was primarily through the regulation of Ca. Elucidating the influence of environmental variables will improve our ability to predict future changes in base cations and thus forest soil health in the greening vegetated Loess Plateau.

Keywords

Soil C/N / Basal area / Random-forest model / Temperate forests / Base cations / Elevation

References

[1] Augustin F, Houle D, Gagnon C, Couture S, Courchesne F. Partitioning the impact of environmental factors on lake concentrations and catchment budgets for base cations in forested ecosystems. Appl Geochem, 2015, 53: 1-12.

[2] Bai YX, Zhou YC, An ZF, Du JJ, Zhang XY, Chang SX. Tree species identity and mixing ratio affected the release of several metallic elements from mixed litter in coniferous-broadleaf plantations in subtropical China. Sci Total Environ, 2022, 838. 156143

[3] Baribault TW, Kobe RK, Rothstein DE. Soil calcium, nitrogen, and water are correlated with aboveground net primary production in northern hardwood forests. For Ecol Manage, 2010, 260(5): 723-733.

[4] Berg B, McClaugherty CPlant litter: decomposition, humus formation, carbon sequestration, 2014BerlinSpringer.

[5] Berger TW. Impact of species composition on forest soil properties of secondary spruce forests and mixed spruce-beech stands. Centralbl Gesammte Forstw, 2001, 118(4): 193-216

[6] Berger TW, Swoboda S, Prohaska T, Glatzel G. The role of calcium uptake from deep soils for spruce (Picea abies) and beech (Fagus sylvatica). For Ecol Manag, 2006, 229(1–3): 234-246.

[7] Bowman WD, Cleveland CC, Halada Ĺ, Hreško J, Baron JS. Negative impact of nitrogen deposition on soil buffering capacity. Nat Geosci, 2008, 1(11): 767-770.

[8] Brady NC, Weil RRThe nature and properties of soils, 2008NJPrentice hall upper saddle river

[9] Carnol M, Bazgir M. Nutrient return to the forest floor through litter and throughfall under 7 forest species after conversion from Norway spruce. For Ecol Manage, 2013, 309: 66-75.

[10] Chen CM, Dynes JJ, Wang J, Karunakaran C, Sparks DL. Soft X-ray spectromicroscopy study of mineral-organic matter associations in pasture soil clay fractions. Environ Sci Technol, 2014, 48(12): 6678-6686.

[11] Clarholm M, Skyllberg U. Translocation of metals by trees and fungi regulates pH, soil organic matter turnover and nitrogen availability in acidic forest soils. Soil Biol Biochem, 2013, 63: 142-153.

[12] Dijkstra FA, Smits MM. Tree species effects on calcium cycling: the role of calcium uptake in deep soils. Ecosystems, 2002, 5(4): 385-398.

[13] Dong Y, Yang J-L, Zhao X-R, Yang S-H, Mulder J, Dörsch P, Peng X-H, Zhang G-L. Soil acidification and loss of base cations in a subtropical agricultural watershed. Sci Total Environ, 2022, 827. 154338

[14] Erickson HE, Helmer EH, Brandeis TJ, Lugo AE. Controls on fallen leaf chemistry and forest floor element masses in native and novel forests across a tropical island. Ecosphere, 2014, 5(4. art48

[15] Feng XM, Fu BJ, Piao SL, Wang S, Ciais P, Zeng ZZ, Lü YH, Zeng Y, Li Y, Jiang XH, Wu BF. Revegetation in China’s Loess Plateau is approaching sustainable water resource limits. Nat Clim Change, 2016, 6(11): 1019-1022.

[16] Feng J, Zhou YC, Bai YX, Fan MY, Wang YX, Tang FH, Feng JR. Changes in rainfall impact the release of metal elements in the litter of a subtropical mixed forest. Environ Res, 2025, 274. 121293

[17] Finzi AC, Canham CD, Van Breemen N. Canopy tree–soil interactions within temperate forests: species effects on pH and cations. Ecol Appl, 1998, 8(2): 447-454.

[18] Fromm J. Wood formation of trees in relation to potassium and calcium nutrition. Tree Physiol, 2010, 30(9): 1140-1147.

[19] Gao Q, Zhang XY, Liu L, Lu XH, Wang YY. A database of atmospheric inorganic nitrogen deposition fluxes in China from satellite monitoring. Sci Data, 2023, 10: 698.

[20] Gao MX, Lin GG, Zhu FF, Wu Z, Gundersen P, Zeng DH, Hobbie EA, Zhu WX, Fang YT. Higher resistance of larch-broadleaf mixed forests than larch forests against soil acidification under experimental nitrogen addition. Plant Soil, 2024, 505(1): 335-349.

[21] Geng AX, Tu QS, Chen JX, Wang WF, Yang HQ. Improving litterfall production prediction in China under variable environmental conditions using machine learning algorithms. J Environ Manag, 2022, 306. 114515

[22] Gransee A, Führs H. Magnesium mobility in soils as a challenge for soil and plant analysis, magnesium fertilization and root uptake under adverse growth conditions. Plant Soil (1/2, Part I: Special Issue: Magnesium in Crop Production, Food Quality and Human Health), 2013, 368(1): 5-21

[23] Haghverdi K, Kooch Y. Effects of diversity of tree species on nutrient cycling and soil-related processes. CATENA, 2019, 178: 335-344.

[24] Hansen TH, Laursen KH, Persson DP, Pedas P, Husted S, Schjoerring JK. Micro-scaled high-throughput digestion of plant tissue samples for multi-elemental analysis. Plant Methods, 2009, 5(1. 12

[25] Heim A, Brunner I, Frey B, Frossard E, Luster J. Root exudation, organic acids, and element distribution in roots of Norway spruce seedlings treated with aluminum in hydroponics. J Plant Nutr Soil Sci, 2001, 164(5): 519-526.

[26] Horn EL, Cooledge EC, Jones DL, Hoyle FC, Brailsford FL, Murphy DV. Addition of base cations increases microbial carbon use efficiency and biomass in acidic soils. Soil Biol Biochem, 2021, 161. 108392

[27] Hüblová L, Frouz J. Contrasting effect of coniferous and broadleaf trees on soil carbon storage during reforestation of forest soils and afforestation of agricultural and post-mining soils. J Environ Manag, 2021, 290. 112567

[28] Jin Z, Luo D, Yu YL, Yang SQ, Zhang J, Cao GF. Soil pH changes in a small catchment on the Chinese Loess Plateau after long-term vegetation rehabilitation. Ecol Eng, 2022, 175. 106503

[29] Lautner S, Fromm J. Calcium-dependent physiological processes in trees. Plant Biol, 2010, 12(2): 268-274.

[30] Lautner S, Ehlting B, Windeisen E, Rennenberg H, Matyssek R, Fromm J. Calcium nutrition has a significant influence on wood formation in poplar. New Phytol, 2007, 173(4): 743-752.

[31] Likens GE, Driscoll CT, Buso DC, Siccama TG, Johnson CE, Lovett GM, Fahey TJ, Reiners WA, Ryan DF, Martin CW, Bailey SW. The biogeochemistry of calcium at Hubbard Brook. Biogeochemistry, 1998, 41(2): 89-173.

[32] Lucas RW, Sponseller RA, Laudon H. Controls over base cation concentrations in stream and river waters: a long-term analysis on the role of deposition and climate. Ecosystems, 2013, 16(5): 707-721.

[33] Marcos E, Calvo L, Marcos JA, Taboada Á, Tárrega R. Tree effects on the chemical topsoil features of oak, beech and pine forests. Eur J for Res, 2010, 129(1): 25-30.

[34] Millar CS (1974) Decomposition of coniferous leaf litter. In: Biology of plant litter decomposition. Elsevier, pp 105–128. https://doi.org/10.1016/b978-0-12-215001-2.50010-6

[35] Perakis SS, Sinkhorn ER, Catricala CE, Bullen TD, Fitzpatrick JA, Hynicka JD, Cromack KJr. Forest calcium depletion and biotic retention along a soil nitrogen gradient. Ecol Appl, 2013, 23(8): 1947-1961.

[36] Reich PB, Oleksyn J, Modrzynski J, Mrozinski P, Hobbie SE, Eissenstat DM, Chorover J, Chadwick OA, Hale CM, Tjoelker MG. Linking litter calcium, earthworms and soil properties: a common garden test with 14 tree species. Ecol Lett, 2005, 8(8): 811-818.

[37] Rowley MC, Grand S, Verrecchia ÉP. Calcium-mediated stabilisation of soil organic carbon. Biogeochemistry, 2018, 137(1): 27-49.

[38] Shabtai IA, Wilhelm RC, Schweizer SA, Höschen C, Buckley DH, Lehmann J. Calcium promotes persistent soil organic matter by altering microbial transformation of plant litter. Nat Commun, 2023, 14: 6609.

[39] Shaul O. Magnesium transport and function in plants: the tip of the iceberg. Biometals, 2002, 15(3): 307-321.

[40] Shi ZJ, Liu SN, Chen YH, Ding DD, Han WX. The unimodal latitudinal pattern of K, Ca and Mg concentration and its potential drivers in forest foliage in eastern China. For Ecosyst, 2024, 11. 100193

[41] Spohn M, Stendahl J. Soil carbon and nitrogen contents in forest soils are related to soil texture in interaction with pH and metal cations. Geoderma, 2024, 441. 116746

[42] St Clair SB, Sharpe WE, Lynch JP. Key interactions between nutrient limitation and climatic factors in temperate forests: a synthesis of the sugar maple literature. Can J for Res, 2008, 38(3): 401-414.

[43] van der Heijden G, Legout A, Pollier B, Mareschal L, Turpault MP, Ranger J, Dambrine E. Assessing Mg and Ca depletion from broadleaf forest soils and potential causes–a case study in the Morvan Mountains. For Ecol Manage, 2013, 293: 65-78.

[44] Wambsganss J, Freschet GT, Beyer F, Goldmann K, Prada-Salcedo LD, Scherer-Lorenzen M, Bauhus J. Tree species mixing causes a shift in fine-root soil exploitation strategies across European forests. Funct Ecol, 2021, 35(9): 1886-1902.

[45] Wang YH, Brandt M, Zhao MF, Tong XW, Xing KX, Xue F, Kang MY, Wang LH, Jiang Y, Fensholt R. Major forest increase on the Loess Plateau, China (2001–2016). Land Degrad Dev, 2018, 29(11): 4080-4091.

[46] Wang BR, Liu D, Yang JJ, Zhu ZL, Darboux F, Jiao JY, An SS. Effects of forest floor characteristics on soil labile carbon as varied by topography and vegetation type in the Chinese Loess Plateau. CATENA, 2021, 196. 104825

[47] Wang ZC, Zhao J, Xiao D, Chen MF, He XY. Higher colonization but lower diversity of root-associated arbuscular mycorrhizal fungi in the topsoil than in deep soil. Appl Soil Ecol, 2024, 194. 105195

[48] Wu XH, Du EZ, Guo YY, Xia N, Tang Y, Wang Y, Guo HB. Climate control of topsoil potassium, calcium, and magnesium concentrations in urban forests across Eastern China. JGR Biogeosci, 2021, 126(9. e2020JG006230

[49] Xie YJ, Li F, Xie YH. Contrasting global patterns and trait controls of major mineral elements in leaf. Glob Ecol Biogeogr, 2023, 32(8): 1452-1461.

[50] Xu XN, Shibata H, Enoki T. Decomposition patterns of leaf litter of seven common canopy species in a subtropical forest: dynamics of mineral nutrients. J Forestry Res, 2006, 17(1): 1-6.

[51] Xue F, Zhao MF, Wang YH, Kang MY, Xing KX, Wang GY, Shi JJ, Chen C, Jiang Y. Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients. J Mt Sci, 2019, 16(1): 30-42.

[52] Xue F, Pan N, Cui HK, Zhao MF, Xing KX, Wang YH, Bai XJ, Liu JZ, Kang MY. Patterns and determinants of calcium concentrations in forest litter and different soil horizons in warm-temperate China. CATENA, 2024, 241. 108069

[53] Yin Y, Zhou YB, Li H, Zhang SZ, Fang YT, Zhang YJ, Zou XM. Linking tree water use efficiency with calcium and precipitation. Tree Physiol, 2022, 42(12): 2419-2431.

[54] Yue K, Ni XY, Fornara DA, Peng Y, Liao S, Tan SY, Wang DY, Wu FZ, Yang YS. Dynamics of calcium, magnesium, and manganese during litter decomposition in alpine forest aquatic and terrestrial ecosystems. Ecosystems, 2021, 24(3): 516-529.

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Northeast Forestry University