Nutrient-induced acidification modulates soil biodiversity-function relationships

Abstract

Nutrient enrichment is a major global change component that often disrupts the relationship between aboveground biodiversity and ecosystem functions by promoting species dominance, altering trophic interactions, and reducing ecosystem stability. Emerging evidence indicates that nutrient enrichment also reduces soil biodiversity and weakens the relationship between belowground biodiversity and ecosystem functions, but the underlying mechanisms remain largely unclear. Here, we explore the effects of nutrient enrichment on soil properties, soil biodiversity, and multiple ecosystem functions through a 13-year field experiment. We show that soil acidification induced by nutrient enrichment, rather than changes in mineral nutrient and carbon (C) availability, is the primary factor negatively affecting the relationship between soil diversity and ecosystem multifunctionality. Nitrogen and phosphorus additions significantly reduce soil pH, diversity of bacteria, fungi and nematodes, as well as an array of ecosystem functions related to C and nutrient cycling. Effects of nutrient enrichment on microbial diversity also have negative consequences at higher trophic levels on the diversity of microbivorous nematodes. These results indicate that nutrient-induced acidification can cascade up its impacts along the soil food webs and influence ecosystem functioning, providing novel insight into the mechanisms through which nutrient enrichment influences soil community and ecosystem properties.

Effect of Soil Acidification on Temperature Sensitivity of Soil Respiration

“…Moreover, the bacterial and fungal r-/K-strategist ratios were significantly different between all treatments and between acidified and non-acidified soils, with no significant variances between low and high temperatures within each treatment (Figure 3b,d). Acidification tends to reduce concentrations of soil alkaline cations, speeding up soil H + pressure and Al 3+ toxicity, leading to loss of bacterial diversity [27,28]. Secondly, soil pH serves an essential role in membrane-bound proton pumps and protein stabilization, affecting microbial physiological activities [27].…”

“…When the pH is low, the concentration of H + and Al 3+ in the soil increases dramatically and damages the absorption and transportation of nutrients in crops. It also destroys the community structure of soil microorganisms, which in turn affects the soil microecosystem and jeopardizes soil health [27,28]. Generally, low soil pH depresses the activity of soil bacteria, reduces the diversity of bacteria, and decreases the relative abundance of the copiotrophic bacterial groups while increasing that of the oligotrophic bacterial groups [29][30][31][32].…”

“…Nutrients required by soil microorganisms and soil respiration, such as nitrogen and organic matter, need to be present for a long time before significant changes occur [50,51]. In long-term acidified soils, soil microbial communities may have adapted to the local environment and may differ from changes in microbial dominant species and community composition in short-term acidified soils [27,28].…”

Soil organic carbon, pH, and ammonium nitrogen controlled changes in bacterial community structure and functional groups after forest conversion

“…Soil pH is a key factor in regulating soil microbial diversity (Bárcenas-Moreno et al, 2016). It may be due to the reason that soil pH plays an important role in the stabilization of cell membrane proton pumps and proteins, thus directly exerting physiological stresses on microorganisms, and when soil pH is outside a certain range (ecological niche), the net growth of unviable individual taxa decreases, which may alter the outcome of the competition Hu et al, 2024). That is appropriate soil pH promotes microbial activity and bacterial growth.…”