Soil C and N cycling in three semiarid vegetation types: Response to an in situ pulse of plant detritus

2008 ◽  
Vol 40 (10) ◽  
pp. 2678-2685 ◽  
Author(s):  
Toby D. Hooker ◽  
John M. Stark
Keyword(s):  
N Cycling ◽  
Vegetation Types ◽  
Soil C ◽  
Plant Detritus ◽  
Soil C And N ◽  
C And N ◽  
C And N Cycling

The magnitude of temperature increase matters: how will soil organic mineralization respond to future climate warming?

2020 ◽  
Author(s):  
Jie Zhou ◽  
Yuan Wen ◽  
Lingling Shi ◽  
Michaela Dippold ◽  
Yakov Kuzyakov ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Climate Warming ◽  
Temperature Increase ◽  
Microbial Growth ◽  
N Cycling ◽  
Soil C ◽  
Soil Microbial ◽  
Soil C And N ◽  
C And N ◽  
C And N Cycling

<p>The Paris climate agreement is pursuing efforts to limit the increase in global temperature to below 2 °C above pre-industrial level. The overall consequence of relatively slight warming (~2 °C), on soil C and N stocks will be dependent on microorganisms decomposing organic matter through release of extracellular enzymes. Therefore, the capacity of soil microbial community to buffer climate warming in long-term and the self-regulatory mechanisms mediating soil C and N cycling through enzyme activity and microbial growth require a detailed comparative study. Here, microbial growth and the dynamics of enzyme activity (involved in C and N cycling) in response to 8 years warming (ambient, +1.6 °C, +3.2 °C) were investigated to identify shifts in soil and microbial functioning. A slight temperature increase (+1.6 °C) only altered microbial properties, but had no effect on either hydrolytic enzyme activity or basic soil properties. Stronger warming (+3.2 °C) increased the specific growth rate (μ<sub>m</sub>) of the microbial community, indicating an alteration in their ecological strategy, i.e. a shift towards fast-growing microorganisms and accelerated microbial turnover. Warming strongly changed microbial physiological state, as indicated by a 1.4-fold increase in the fraction of growing microorganisms (GMB) and 2 times decrease in lag-time with warming. This reduced total microbial biomass but increased specific enzyme activity to be ready to decompose increased rhizodeposition, as supported by the higher potential activitiy (V<sub>max</sub>) and lower affinity to substrates (higher K<sub>m</sub>) of enzymes hydrolyzing cellobiose and proteins cleavage in warmed soil. In other words, stronger warming magnitude (+3.2 °C) changed microbial communities, and was sufficient to benefit fast-growing microbial populations with enzyme functions that specific to degrade labile SOM. Combining with 48 literature observations, we confirmed that the slight magnitude of temperature increase (< 2 °C) only altered microbial properties, but further temperature increases (2-4 °C) was sufficient to change almost all soil, microbial, and enzyme properties and related processes. As a consequence, the revealed microbial regulatory mechanism of stability of soil C storage is strongly depended on the magnitude of future climate warming.</p>

Nitrogen supply modulates the effect of changes in drying-rewetting frequency on soil C and N cycling and greenhouse gas exchange

2015 ◽  
Vol 21 (10) ◽  
pp. 3854-3863 ◽  
Author(s):  
Lourdes Morillas ◽  
Jorge Durán ◽  
Alexandra Rodríguez ◽  
Javier Roales ◽  
Antonio Gallardo ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Greenhouse Gas ◽  
Nitrogen Supply ◽  
N Cycling ◽  
Soil C ◽  
Soil C And N ◽  
C And N ◽  
C And N Cycling

Forest restoration treatments have subtle long-term effects on soil C and N cycling in mixed conifer forests

2016 ◽  
Vol 26 (5) ◽  
pp. 1503-1516 ◽  
Author(s):  
Peter W. Ganzlin ◽  
Michael J. Gundale ◽  
Rachel E. Becknell ◽  
Cory C. Cleveland
Keyword(s):  
Forest Restoration ◽  
N Cycling ◽  
Long Term Effects ◽  
Mixed Conifer ◽  
Soil C ◽  
Mixed Conifer Forests ◽  
Soil C And N ◽  
C And N ◽  
C And N Cycling

scholarly journals Modeling the effects of tree species and incubation temperature on soil's extracellular enzyme activity in 78-year-old tree plantations

2017 ◽  
Vol 14 (23) ◽  
pp. 5393-5402 ◽  
Author(s):  
Xiaoqi Zhou ◽  
Shen S. J. Wang ◽  
Chengrong Chen
Keyword(s):  
Tree Species ◽  
Incubation Temperature ◽  
N Cycling ◽  
Residual Soil ◽  
Coniferous Tree ◽  
Soil C ◽  
Hoop Pine ◽  
Soil C And N ◽  
C And N ◽  
Coniferous Tree Species

Abstract. Forest plantations have been widely used as an effective measure for increasing soil carbon (C), and nitrogen (N) stocks and soil enzyme activities play a key role in soil C and N losses during decomposition of soil organic matter. However, few studies have been carried out to elucidate the mechanisms behind the differences in soil C and N cycling by different tree species in response to climate warming. Here, we measured the responses of soil's extracellular enzyme activity (EEA) to a gradient of temperatures using incubation methods in 78-year-old forest plantations with different tree species. Based on a soil enzyme kinetics model, we established a new statistical model to investigate the effects of temperature and tree species on soil EEA. In addition, we established a tree species–enzyme–C∕N model to investigate how temperature and tree species influence soil C∕N contents over time without considering plant C inputs. These extracellular enzymes included C acquisition enzymes (β-glucosidase, BG), N acquisition enzymes (N-acetylglucosaminidase, NAG; leucine aminopeptidase, LAP) and phosphorus acquisition enzymes (acid phosphatases). The results showed that incubation temperature and tree species significantly influenced all soil EEA and Eucalyptus had 1.01–2.86 times higher soil EEA than coniferous tree species. Modeling showed that Eucalyptus had larger soil C losses but had 0.99–2.38 times longer soil C residence time than the coniferous tree species over time. The differences in the residual soil C and N contents between Eucalyptus and coniferous tree species, as well as between slash pine (Pinus elliottii Engelm. var. elliottii) and hoop pine (Araucaria cunninghamii Ait.), increase with time. On the other hand, the modeling results help explain why exotic slash pine can grow faster, as it has 1.22–1.38 times longer residual soil N residence time for LAP, which mediate soil N cycling in the long term, than native coniferous tree species like hoop pine and kauri pine (Agathis robusta C. Moore). Our results will be helpful for understanding the mechanisms of soil C and N cycling by different tree species, which will have implications for forest management.

The use of diffuse reflectance spectroscopy for in situ carbon and nitrogen analysis of pastoral soils

Soil Research ◽  
2008 ◽  
Vol 46 (7) ◽  
pp. 623 ◽  
Author(s):  
Bambang H. Kusumo ◽  
C. B. Hedley ◽  
M. J. Hedley ◽  
A. Hueni ◽  
M. P. Tuohy ◽  
...  
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Soil Surface ◽  
Soil Core ◽  
Least Squares Regression ◽  
Soil C ◽  
Wide Range ◽  
In Situ Assessment ◽  
Soil C And N ◽  
C And N

A field method has been developed for rapid in situ assessment of soil carbon (C) and nitrogen (N) content using a portable spectroradiometer (ASD FieldSpecPro). The technique was evaluated at 7 field sites in permanent pasture, and in 1-year, 3-year, and 5-year pine-to-pasture conversions on Pumice, Allophanic, and Tephric Recent Soils in the Taupo and Rotorua region of New Zealand. A total of 210 samples were collected from 2 depths: 37.5 and 112.5 mm. Field measurement of diffuse spectral reflectance was recorded from a flat sectioned horizontal soil surface of a soil core using a purpose-built contact probe attached by fibre optic cable to the spectroradiometer. A 15-mm soil slice was collected from each cut surface for analysis of total C and N using a LECO Analyser. Soils had a wide range of total C and N (0.26–11.21% C, 0.02–1.01% N). Partial least-squares regression analysis was used to develop calibration models between smoothed-first derivative 5-nm-spaced spectral data and LECO-measured total C and N. The models successfully predicted total C and N in the validation sets with the best prediction for C (RPD 2.01, r2 0.75, RMSEP 1.21%) and N (RPD 2.66, r2 0.86, RMSEP 0.07%). Prediction accuracy using different selection methods of calibration and validation set is reported. This study indicates that in situ assessment of soil C and N by field spectroscopy has considerable potential for spatially rapid measurement of soil C and N in the landscape.

scholarly journals Effects of litter and root manipulations on soil carbon and nitrogen in a Schrenk’s spruce (Picea schrenkiana) forest

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247725
Author(s):  
Haiqiang Zhu ◽  
Lu Gong ◽  
Zhaolong Ding ◽  
Yuefeng Li
Keyword(s):  
Enzyme Activity ◽  
Microbial Biomass ◽  
Organic Carbon ◽  
Soil Carbon ◽  
Abiotic Factors ◽  
Soil C ◽  
Plant Detritus ◽  
Soil C And N ◽  
C And N ◽  
Root Exclusion

Plant detritus represents the major source of soil carbon (C) and nitrogen (N), and changes in its quantity can influence below-ground biogeochemical processes in forests. However, we lack a mechanistic understanding of how above- and belowground detrital inputs affect soil C and N in mountain forests in an arid land. Here, we explored the effects of litter and root manipulations (control (CK), doubled litter input (DL), removal of litter (NL), root exclusion (NR), and a combination of litter removal and root exclusion (NI)) on soil C and N concentrations, enzyme activity and microbial biomass during a 2-year field experiment. We found that DL had no significant effect on soil total organic carbon (SOC) and total nitrogen (TN) but significantly increased soil dissolved organic carbon (DOC), microbial biomass C, N and inorganic N as well as soil cellulase, phosphatase and peroxidase activities. Conversely, NL and NR reduced soil C and N concentrations and enzyme activities. We also found an increase in the biomass of soil bacteria, fungi and actinomycetes in the DL treatment, while NL reduced the biomass of gram-positive bacteria, gram-negative bacteria and fungi by 5.15%, 17.50% and 14.17%, respectively. The NR decreased the biomass of these three taxonomic groups by 8.97%, 22.11% and 21.36%, respectively. Correlation analysis showed that soil biotic factors (enzyme activity and microbial biomass) and abiotic factors (soil moisture content) significantly controlled the change in soil C and N concentrations (P < 0.01). In brief, we found that the short-term input of plant detritus could markedly affect the concentrations and biological characteristics of the C and N fractions in soil. The removal experiment indicated that the contribution of roots to soil nutrients is greater than that of the litter.

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