Impacts of conversion from secondary forests to larch plantations on the structure and function of microbial communities

Peer Review #2 of "Variation of soil bacterial communities along a chronosequence of Eucalyptus plantation (v0.1)"

“…Acidobacteria have been reported in oligotrophic habitats with low nutrient concentrations, as well as a wide range of metabolic organic matter, low C mineralization rate and ability to tolerate fluctuations in adverse soil conditions (Aislabie & Deslippe, 2013;Fierer et al, 2007;Rampelotto et al, 2013). Since Proteobacteria and Acidobabcteira could be considered as indicators of soil trophic level organisms (Smit et al, 2001;Zhang et al, 2017), the change from secondary-forest to Eucalyptus or stand age of Eucalyptus generated little effect on declining soil nutrition and metabolizing organic resource within the ten-year Eucalyptus plantation. Bacteria belonging to the phylum Actinobacteria were more dominant in impacted soils.…”

“…Actinobacteria observed in impacted soils (2YR and 10YR), because of its higher ability to consume organic carbon pools and its copiotrophs lifestyle (Rampelotto et al, 2013;Zhang et al, 2017;He et al, 2012). Significant variation in the genus Bradyrhizobium between impacted and low impacted clusters illustrates the low ability of nitrogen-fixing in the Eucalyptus plantation (Silva et al, 2014).…”

“…This is contradictory to other studies reported which demonstrate that Eucalyptus plantations reduced microbial biomass, soil organic carbon and nitrogen concentrations during continuous planting (Behera & Sahani, 2003;Cortez et al, 2014).Another relevant study of secondary tropical forest (SF) converted into Eucalyptus plantations (EP) using high-throughput sequencing techniques revealed a significant difference between SF and EP samples in bacterial composition and diversity (Lan et al, 2017). Given that these tools can elucidate the impact of artificial planting, especially on the surrounding soil ecosystem affected by the functioning of microbial communities if impacted (Zhang et al, 2017;Zheng et al, 2017;Lin et al, 2017), their application will better define the response of soil microbial community diversity and function to land use shift and long-term Eucalyptus plantation, which remains obscure.…”

Nutrient Allocation to Different Compartments of Age-Sequence Larch Plantations in China

“…Thus, it is essential to understand nutrient allocation among different compartments of the larch ecosystem in order to analyze nutrient losses as a consequence of harvesting and to establish an optimal harvesting regime. Although few studies have reported on nutrient accumulation in larch plantations, these studies mainly focus on changes in nutrient accumulation in vegetation and the forest floor [28][29][30], without considering the ideal soil nutrient storage (pool size on a volumetric basis) for estimating nutrient balances [26].In this study, nutrient allocation (N, P, K, Ca, and Mg) was evaluated in different compartments of the larch ecosystem, including the trees, understory, and forest floor, as well as the rarely reported soil layer. The objectives of this study were to explore the following questions:(1) what are the conditions of nutrient allocation in the trees, understory, forest floor, and soil in age-sequence larch plantations; (2) how significant are the effects on nutrient removal due to harvesting ecosystem nutrient pools; and (3) what is the optimum harvesting method in larch plantations required to maximize biomass harvesting while minimizing nutrient loss.…”

“…Thus, it is essential to understand nutrient allocation among different compartments of the larch ecosystem in order to analyze nutrient losses as a consequence of harvesting and to establish an optimal harvesting regime. Although few studies have reported on nutrient accumulation in larch plantations, these studies mainly focus on changes in nutrient accumulation in vegetation and the forest floor [28][29][30], without considering the ideal soil nutrient storage (pool size on a volumetric basis) for estimating nutrient balances [26].…”