Effect of monospecific and mixed Cunninghamia lanceolata plantations on microbial community and two functional genes involved in nitrogen cycling

Abstract

Conversion of native broadleaf forest (NF) and introduction of broadleaf species into monospecificCunninghamia lanceolata plantations are silvicultural practices driven by the increasing demand for timber production. This study was conducted to evaluate the impacts of successive planting of C. lanceolata and mixed plantations (C. lanceolata-Michelia macclurei, CFM; C. lanceolata-Alnus cremastogyne, CFA; C. lanceolata-Kalopanax septemlobus, CFK) on microbial community diversity. Microbial biomass (MBC) was assessed using chloroform fumigation-extraction. Using denaturing gradient gel electrophoresis (DGGE), we examined the biodiversity within eubacterial (16S rRNA gene) and fungal (28S rRNA gene) species and two genes involved in N cycling: nifH and amoA. Microbial community diversities and microbial biomass decreased as NF was substituted by successive plantings of C. lanceolata plantations, whereas the trend reversed after introducing the broadleaf, M. macclurei, into pure C. lanceolata plantations. A strong positive correlation between MBC changes and total organic C (TOC), total organic N (TON), available N and extractable C (C ext ) were seen, which suggests that MBC was tightly coupled with the content of soil organic matter. The Shannon index showed that bacterial diversity and two functional genes (nifH and amoA) diversities associated with monospecific C. lanceolata plantations were lower than that of NF or mixed C. lanceolata plantations, such as CFM and CFA, whereas the opposite was seen for fungal diversity. Bacterial diversity was positively correlated with pH, TOC, TON, C ext and NH 4 + -N; while fungal diversity was positively correlated with C/N ratio and negatively correlated with pH. Both nitrogen fixing and ammonia oxidizing bacterial diversities were positively correlated with pH. Thus, soil pH was not only significantly positively correlated with bacterial diversity (r=0.502, P<0.05), nifH gene diversity (r=0.564, P<0.01) and amoA gene diversity (r=0.659, P<0.001), but also negatively correlated with fungal diversity (r=− 0.505, P<0.05), which seemed to be responsible for the discrimination of the soil microbial communities among these plantations. These findings suggest that different silvicultural practices have Plant Soil (2010) 327:413-428

A broadleaf species enhances an autotoxic conifers growth through belowground chemical interactions

“…, Liu et al. ). However, the mechanisms underlying the facilitative interactions between these two tree species are largely unknown.…”

“…Compared to monospecific plantations, Chinese fir trees in mixedspecies forests show increased regeneration and productivity. One of the explanations for this positive effect is that M. macclurei improves soil fertility and microbial activity through an enhancement of litter decomposition rates and nutrient availability (Huang et al 2004, Liu et al 2010). However, the mechanisms underlying the facilitative interactions between these two tree species are largely unknown.…”

Application of Cloud Model to Evaluation of Forest Soil Fertility: A Case in Chinese Fir Plantations in Southern China

“…Second, the use of chemical fertilizers or acid rain may lead to soil acidification [30,31]. In addition, the accumulation of organic acids and phenolic substances from the litter of coniferous trees, such as Chinese fir, is also an important factor in the process of soil acidification [32].…”

New Ceratocystis species from Eucalyptus and Cunninghamia in South China

“…A similar situation is true for Cunninghamia lanceolata (Lamb.) Hook, which is native in China and is being used in large afforestation projects, particularly in southern China (Camille and Morrell 2006) and due to its rapid growth and naturally durable heartwood (Liu et al 2010). Despite the growing importance of Eucalyptus and other plantation species in China, information regarding fungal diseases affecting these plantations is limited (Zhou and Wingfield 2011).…”