The Spatial Factor, Rather than Elevated CO ₂ , Controls the Soil Bacterial Community in a Temperate Forest Ecosystem

Abstract

The global atmospheric carbon dioxide (CO 2 ) concentration is expected to increase continuously over the next century. However, little is known about the responses of soil bacterial communities to elevated CO 2 in terrestrial ecosystems. This study aimed to partition the relative influences of CO 2 , nitrogen (N), and the spatial factor (different sampling plots) on soil bacterial communities at the free-air CO 2 enrichment research site in Duke Forest, North Carolina, by two independent techniques: an entirely sequencing-based approach and denaturing gradient gel electrophoresis. Multivariate regression tree analysis demonstrated that the spatial factor could explain more than 70% of the variation in soil bacterial diversity and 20% of the variation in community structure, while CO 2 or N treatment explains less than 3% of the variation. For the effects of soil environmental heterogeneity, the diversity estimates were distinguished mainly by the total soil N and C/N ratio. Bacterial diversity estimates were positively correlated with total soil N and negatively correlated with C/N ratio. There was no correlation between the overall bacterial community structures and the soil properties investigated. This study contributes to the information about the effects of elevated CO 2 and soil fertility on soil bacterial communities and the environmental factors shaping the distribution patterns of bacterial community diversity and structure in temperate forest soils.

Abundance and community structure of ammonia-oxidizing bacteria and archaea in a temperate forest ecosystem under ten-years elevated CO2

“…Responses of AOB and AOA community structure to elevated CO 2 and N fertilization CCA results revealed that soil niche properties significantly influenced the amoA genotype distribution of AOB and AOA rather than elevated CO 2 (p > 0.1) or N fertilization (p > 0.1). Previous study of this site already showed that the spatial difference rather than elevated CO 2 shaped the distribution of bacterial community (Ge et al, 2010). A study on the response of AOB and AOA in the rhizosphere of maize and soybean to elevated CO 2 showed no significant difference among treatments based on unweighted PCA of the amoA gene sequences (Nelson et al, 2010).…”

“…35% mostly since the beginning of industrialization. Atmospheric CO 2 enrichment has been shown to significantly influence the structure and function of terrestrial ecosystems (Rosenzweig et al, 2007), adding to or interacting with the spatial and temporal effects of environmental variables (Ge et al, 2010). Soil microorganisms, encompassing the greatest diversity in terrestrial ecosystems, are the key drivers in almost all global biogeochemical cycles (Fuhrman, 2009).…”

“…It has been suggested that global changes (e.g., elevated atmospheric CO 2 and N deposition) may change the resource availability (e.g., C or N) and quality, leading to shifts in the abundance and community structure of ammonia oxidizers (Horz et al, 2004). Previous studies at the Duke free-air CO 2 enrichment (FACE) site indicated that both elevated CO 2 and N fertilization altered soil microbial community composition based on phospholipid fatty acid (PLFA) profiling (Feng et al, 2010), whereas another study suggested that the bacterial community composition was more influenced by spatial variations than the CO 2 enrichment (Ge et al, 2010). Increased allocation of C (carbohydrates) into the soil under elevated CO 2 (Palmroth et al, 2006) and enhanced soil N availability with N fertilization have led to the shifts in the abundance and composition of soil microbial communities .…”

Abundance and community structure of ammonia oxidizing bacteria and archaea in a Sweden boreal forest soil under 19-year fertilization and 12-year warming

“…Research regarding effects of global change on soil microbial communities has focussed largely on community structure associated with a single environmental factor such as elevated [CO 2 ], nitrogen (N) deposition, and warming. However, in these experiments, effects of associated global change factors potentially varied with treatment length and type, ecosystem and soil type, and other environmental conditions (Montealegre et al 2000;Frey et al 2008;Xu et al 2009;Ge et al 2010). Given that soil microorganisms are the key drivers of soil nutrient cycling (e.g., Falkowski et al 2008), their roles in mediating climate change and ecosystem functioning are not well understood (Balser et al 2001).…”

Impact of Different Methods of Soil Sampling and DNA Extraction on the Identification of Soil Bacterial Abundance under Elevated CO2

“…The soil sampling approach most widely used in CO 2 studies is the bulked soil method providing a single soil sample per FACE ring or OTC; examples where bacterial abundance has been measured are given in Table 1 and there are further examples where the object was to study bacterial community structure and diversity [42] [16]. The results for bacterial abundance in eCO 2 field experiments shows a consistent reduction in abundance with eCO 2 ; the only exception in the experiments listed being a slight and non-significant response in one set of measurements in this paper (Figure 3(B)).…”