Plantations of Cinnamomum camphora (Linn) Presl with Distinct Soil Bacterial Communities Mitigate Soil Acidity within Polluted Locations in Southwest China

Abstract

Although the underlying mechanisms remain unknown, soils from different forest types exhibit distinct acidification-buffering capacities. We investigated soil properties and bacterial communities across five plantation types and different soil horizons in a severely acid-polluted site in Southwest China and evaluated the potential mechanisms driving differences in community structure. Soils collected from pure stands of Pinus massoniana Lamb.or Schima superba Gardn. et Champ. or mixed stands of these species showed the lowest soil pH and greater abundances of acid-producing and acidophilic taxa (Halanaerobiales and Rhodospirillales). Soils from pure stands of Cinnamomum camphora (Linn) Presl, or a mixture of C. camphora and P. massoniana, yielded the greatest concentrations of exchangeable calcium (Ca) and magnesium (Mg) and greater soil pH. Increased relative abundances of beneficial taxa may have contributed to soil aggregate formation (e.g., Bradyrhizobium canariense and Terracidiphilus sp.) and heightened environmental stress resistance (e.g., Gaiellales). Fewer acid-producing and acidophilic taxa found in soils associated with C. camphora suggest that planting C. camphora may help soils recover from acidification, while planting S. superba may not be as beneficial. Our findings illustrate how differences in soil microbial communities may impact soil-acidification-buffering capacity across different forest types, which have important implications for understanding environmental functions within the context of microbial diversity.

Effects of Forest Type on Nutrient Fluxes in Throughfall, Stemflow, and Litter Leachate within Acid-Polluted Locations in Southwest China

“…Our data showed that throughfall N input was negatively associated with soil pH, which is supported by a study from an urban-to-rural transect in southern China [ 55 ]. In this study, throughfall NO 3 − flux was the highest in Pi stands, and the lowest in Ci stands, where lower N input of throughfall (plus stemflow) and litter leachate contributed to higher pH values of the soils, an observation supported by our previous data as well [ 10 ].…”

“…The study site in Han et al [ 27 ] was located in northwest China, which does not experience acid rain or soil acidification [ 53 ]. Our study was conducted in a typical acid-polluted area with severely acidic soil (average pH of 3.98, 4.54, and 4.6, respectively, in O_horizon of Pi, Pi_Ci and Ci, [ 10 ]), which would benefit from species that could supply less acidic rain water and greater base saturation. We also calculated the base saturation of throughfall, stemflow, and litter leachate, finding that Ci had the highest base saturation, followed by Pi_Ci ( Table 4 ).…”

“…In June 2018, in each of the three different forest stands (Pi, Pi_Ci, Ci) we established four 20 m × 20 m square study plots. The details about the study site can be found in Chen et al [ 10 ]. The soil is classified as Haplic Acrisol in FAO (IUSS Working Group WRB, 2006), with low pH values (3.80–4.54 from the O horizon to the lower A horizon) [ 10 ].…”

“…The details about the study site can be found in Chen et al [ 10 ]. The soil is classified as Haplic Acrisol in FAO (IUSS Working Group WRB, 2006), with low pH values (3.80–4.54 from the O horizon to the lower A horizon) [ 10 ].…”

“…Soil acidification caused by acid deposition has adverse effects on ecosystems, particularly forest ecosystems [ 5 ]. Numerous studies report the damage of acid deposition on forests, including decreased growth and dieback [ 6 ], changing biogeochemical cycles [ 7 ], altered aboveground and belowground biomes [ 8 , 9 , 10 ], and impacts on ecosystem function and sustainability [ 11 , 12 ]. Additionally, despite reductions of acidic anion inputs [ 13 , 14 ], the recovery of acidified soils could be delayed due to historic adsorption of SO 4 2− into soils [ 1 ].…”