Abstract
Restoration of reclaimed marshes has great effects on soil biological processes. However, the responses of soil microbial properties (microbial biomass and enzyme activities) to natural restoration of reclaimed marshes is poorly studied, especially in a long restoration chronosequence. This study assessed the responses of soil microbial properties to natural restoration and investigated the relationships between soil microbial properties and soil physico-chemical and plant properties. We selected a restoration chronosequence (1, 4, 8, 13, 17, 27 years) after farmland abandonment, a soybean field, and a natural marsh in Sanjiang Plain, northeast China. For each site, we analyzed the soil microbial biomass carbon and nitrogen (MBC and MBN), four enzymes (β-glucosidase, invertase, catalase, urease) activities, soil physico-chemical properties at 0–50 cm depths, and plant properties (biomass, height, and coverage). The MBC and MBN contents increased with restoration time, but MBN content slowed down after 8 years of restoration. After 27 years of restoration, the soil MBC and MBN contents were 15.7 and 3.2 times of those in the soybean field, but the largest contents of MBC and MBN in the restored sites were 7.78%, 27.76% lower than those in natural marshes, respectively. Moreover, soil enzyme activities and the geometric mean of enzymatic activities (GME) also increased with restoration but slowed down after 13 years of restoration. After 27 years of restoration, the GME was 2.9 times than that in the soybean field, but the largest GME in the restored sites was 31.15% lower than that in the natural marsh. MBC and MBN contents, soil enzyme activities, and GME had significant relationships with soil C:N ratio, organic carbon, nutrients (total nitrogen, available nitrogen, total phosphorus), bulk density, moisture content, pH, plant properties, (i.e. biomass, height, and coverage) (p < 0.01). Redundancy analysis revealed that soil C:N ratio, pH, moisture content, total nitrogen and phosphorus were main factors affecting MBC and MBN contents and enzyme activities. In conclusion, soil microbial properties can respond positively to the natural restoration process of the reclaimed marshes and were significantly correlated with specific parameters of soil physico-chemical and plant properties.
Highlights
Wetland restoration has become more important in the past 2 decades (Euliss et al, 2006; Marton et al, 2014a), as disturbed/ degraded wetland have been found to reduce the functions of water storage, flood control, carbon (C) and nitrogen (N) sequestration, biodiversity conservation, etc. (Jiang et al, 2015; Yu et al, 2017; Qi et al, 2021)
The results support part of our first hypothesis that soil microbial biomass will increase over restoration time
This result is consistent with previous studies (Song et al, 2012; Zhang et al, 2018; Feng et al, 2019; MoralesLondoño et al, 2019) on the changes of soil microbial biomass in the process of ecosystem restoration after abandonment
Summary
Wetland restoration has become more important in the past 2 decades (Euliss et al, 2006; Marton et al, 2014a), as disturbed/ degraded wetland have been found to reduce the functions of water storage, flood control, carbon (C) and nitrogen (N) sequestration, biodiversity conservation, etc. (Jiang et al, 2015; Yu et al, 2017; Qi et al, 2021). Soil microorganisms play a great role in the biogeochemical process of wetlands (Sousa et al, 2015) and can provide nutrients for the development and function of soil and plants (Li et al, 2015; Xu et al, 2020) Soil microbial properties such as microbial biomass and enzyme activities are essential components of wetlands (Xiao et al, 2015). They are considered to be more sensitive parameters than physico-chemical properties important indicators and could reflect the changes in soil properties after ecosystem restoration (Araujo et al, 2013; Zhang et al, 2015; Kabiri et al, 2016). Babujia et al (2010) and Zhang et al (2018) found that soil microbial biomass and enzyme activities can be influenced by the ecosystem restoration after farmland abandonment
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