Afforestation of pastures with Pinus radiata influences soil carbon and nitrogen pools and mineralisation and microbial properties

Soil Research ◽  
2002 ◽  
Vol 40 (8) ◽  
pp. 1303 ◽  
Author(s):  
D. J. Ross ◽  
K. R. Tate ◽  
N. A. Scott ◽  
R. H. Wilde ◽  
N. J. Rodda ◽  
...  

In New Zealand, Pinus radiata D. Don is frequently planted on land under pasture primarily for production forestry, but with the added advantage of potentially offsetting carbon dioxide (CO2) emissions from energy and industrial sources. Conversion of pasture to P. radiata plantations can, however, result in lowered contents of soil carbon (C) at some sites. We here examine the effects of this land-use change on soil C and nitrogen (N) pools, and on microbial properties involved in the cycling of these nutrients, at 5 paired sites, each with an established pasture and P. radiata plantation. Four sites had first-rotation trees aged 12–30 years and the other site second-rotation trees aged 20 years. In mineral soil at 0–10 cm depth, total and microbial C and N, extractable C, CO2-C production, and, generally, net mineral-N production were lower under P. radiata than under pasture; differences were significant (P < 0.05), except for total and extractable C at 2 sites. Differences between these land uses were less distinct in soil at 10–30 cm depth. On an area basis, total C in 0–30 cm depth soil was lower under P. radiata than under pasture at most sites, but significantly lower at only one site. Total N, microbial C and N, and CO2-C and net mineral-N production were, however, again generally significantly lower under P. radiata. These ecosystem differences were less marked, although still present, except for CO2-C production, when forest litter (LFH material) was included in the area calculations. Overall, our study suggests that afforestation with P. radiata leads to a reduction in total N, microbial biomass, and microbial activity, but a less consistent effect on soil C storage after one rotation.


Soil Research ◽  
2001 ◽  
Vol 39 (5) ◽  
pp. 1027 ◽  
Author(s):  
Des J. Ross ◽  
Neal A. Scott ◽  
Kevin R. Tate ◽  
Natasha J. Rodda ◽  
Jackie A. Townsend

Although the contribution of roots to soil carbon (C) fluxes and biochemical processes is recognised, it is difficult to quantify. One approach to assess their importance is the use of trenched plots, in which C inputs to the soil and respiration by living roots has ceased. We give here an account of C and nitrogen (N) pools and mineralisation in samples taken 27 months after trenching in a 26-year-old Pinus radiata D. Don plantation on a coastal sand (an Aquic Udipsamment); above-ground litter inputs continued throughout the 27-month period.Moisture contents were higher in FH material and mineral soil from the trenched than from the control plots. Trenching had no effect on total organic C and N concentrations, but led to decreases in extractable C, microbial C and N, and CO2-C production values at some depths in the soil profile. Mineral-N concentrations and gross nitrification rates were, in contrast, initially higher in the trenched-plot samples, but were similar in both treatments after incubation of the samples at 25°C for 57 days. Mineral-N concentrations were also higher in the trenched than control mineral soil after in situ incubation. On an area basis (to 20 cm depth of mineral soil), inputs from roots were estimated to account for about 40% of the extractable C pool, 28% of microbial C, 26% of microbial N, and 23% of heterotrophic CO2-C production (0–7 days at 25°C) in the control soil. Overall, our results suggest a tight connection between N cycling rates and the labile C pools derived from below-ground inputs, with nitrification in particular increasing as C availability declined as a result of trenching.



Soil Research ◽  
2011 ◽  
Vol 49 (6) ◽  
pp. 494 ◽  
Author(s):  
R. L. Parfitt ◽  
D. J. Ross

Planting of Pinus radiata D. Don in previously grazed pastures is a common land-use change in New Zealand. Although carbon (C) accumulates relatively rapidly in the trees, there have been no studies of the annual effect on soil C content during the early years of establishment. Here, we study soil properties under P. radiata and pasture each year over 11 years after P. radiata was planted into pasture that had been grazed by sheep. Under the growing trees, grass was gradually shaded out by the unpruned trees, and completely disappeared after 6 years; needle litterfall had then increased appreciably. By year 9, soil microbial C and nitrogen (N), and net N mineralisation, were significantly lower under pine than under pasture. Soil pH, sampled at 0–100 mm in early spring each year, decreased by ~0.3 units under pine and increased by ~0.3 units under pasture. Close to the pine stems, total C and N decreased significantly for 3 years, while ~100 kg N/ha accumulated in the trees. Soil C and N increased in subsequent years, when litterfall increased. Overall, the mineral soil under pine lost ~500 kg N/ha over 11 years, consistent with uptake by the trees. Leaching losses (estimated using lysimeters) in year 9 were 4.5 kg N/ha.year. These data indicate that ~6 Mg C/ha may have been lost from the mineral soil at this site. The difficulties associated with measuring losses of C are discussed.



1995 ◽  
Vol 25 (8) ◽  
pp. 1385-1396 ◽  
Author(s):  
T.A. Black ◽  
J.W. Harden

Four plots from a mixed conifer forest were similarly cleared, burned, and replanted at various times over 17 years; a plot logged 79 years before sampling was used as a control. The plots had similar slope (2 to 15%, midslope position), aspect (south to southeast), and soil type (Holland series: mesic Haploxeralf; a Gray Brown Luvisol in the Canadian classification system). Twenty sites at each plot were sampled volumetrically by horizon to 20 cm below the organic–mineral soil boundary. Samples were analyzed for bulk density, organic C, and total N. There was an initial loss (15%) of organic C from the soil within 1 to 7 years, likely the result of oxidation (burning and decomposition) and erosion. For 17 years of forest regrowth, the soil continued to lose C (another 15%), probably owing to decomposition of slash material and possibly erosion, despite the slight accumulation of new litter and roots. After 80 years of regrowth, rates of carbon accumulation exceeded rates of loss, but carbon storage had declined and was not likely to recover to preharvest levels. Timber harvest and site preparation dramatically altered soil C and N distribution, in which C/N ratios after site preparation were initially high throughout the upper 20 cm. Subsequently, C/N ratios became lower with depth and with recovery age. Although stocks of C and N varied considerably among the plots and did not change consistently as a function of recovery age, the C/N ratios did vary systematically with recovery age. We hypothesize that the amount of C ultimately stored in the soil at steady state depends largely on N reserves and potentials, which appear to vary with erosion, intensity of burning, and site treatment.



2019 ◽  
Vol 28 (10) ◽  
pp. 814 ◽  
Author(s):  
Derek N. Pierson ◽  
Peter R. Robichaud ◽  
Charles C. Rhoades ◽  
Robert E. Brown

Erosion of soil carbon (C) and nitrogen (N) following severe wildfire may have deleterious effects on downstream resources and ecosystem recovery. Although C and N losses in combustion and runoff have been studied extensively, soil C and N transported by post-fire erosion has rarely been quantified in burned landscapes. To better understand the magnitude and temporal pattern of these losses, we analysed the C and N content of sediment collected in severely burned hillslopes and catchments across the western USA over the first 4 post-fire years. We also compared soil C and N losses from areas receiving common erosion-mitigation treatments and untreated, burned areas. The concentrations of C and N in the eroded material (0.23–0.98gCkg−1 and 0.01–0.04gNkg−1) were similar to those of mineral soils rather than organic soil horizons or combusted vegetation. Losses of eroded soil C and N were highly variable across sites, and were highest the first 2 years after fire. Cumulative erosional losses from untreated, burned areas ranged from 73 to 2253kgCha−1 and from 3.3 to 110kgNha−1 over 4 post-fire years. Post-fire erosion-mitigation treatments reduced C and N losses by up to 75% compared with untreated areas. Losses in post-fire erosion are estimated to be &lt;10% of the total soil C and N combusted during severe wildfire and &lt;10% of post-fire soil C and N stocks remaining in the upper 20cm of mineral soil. Although loss of soil C and N in post-fire erosion is unlikely to impair the productivity of recovering vegetation, export of C and N may influence downstream water quality and aquatic ecosystems.



2006 ◽  
Vol 36 (3) ◽  
pp. 565-576 ◽  
Author(s):  
Felipe G Sanchez ◽  
Allan E Tiarks ◽  
J Marty Kranabetter ◽  
Deborah S Page-Dumroese ◽  
Robert F Powers ◽  
...  

This study describes the main treatment effects of organic matter removal and compaction and a split-plot effect of competition control on mineral soil carbon (C) and nitrogen (N) pools. Treatment effects on soil C and N pools are discussed for 19 sites across five locations (British Columbia, Northern Rocky Mountains, Pacific Southwest, and Atlantic and Gulf coasts) that are part of the Long-Term Soil Productivity (LTSP) network and were established over 5 years ago. The sites cover a broad range of soil types, climatic conditions, and tree species. Most sites showed increased soil C and N levels 5 years after study establishment; however, the rate and magnitude of the changes varied between sites. Organic matter removal, compaction, or competition control did not significantly affect soil C and N contents at any site, except for the Northern Rocky Mountain site, where competition control significantly affected soil C and N contents. The observation that, after 5 years, the soil C and N contents were not negatively affected by even the extreme treatments demonstrates the high resiliency of the soil, at least in the short term, to forest management perturbations.



2021 ◽  
Vol 11 (5) ◽  
pp. 2139
Author(s):  
Junliang Zou ◽  
Bruce Osborne

The importance of labile soil carbon (C) and nitrogen (N) in soil biogeochemical processes is now well recognized. However, the quantification of labile soil C and N in soils and the assessment of their contribution to ecosystem C and N budgets is often constrained by limited information on spatial variability. To address this, we examined spatial variability in dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) in a Sitka spruce forest in central Ireland. The results showed moderate variations in the concentrations of DOC and DTN based on the mean, minimum, and maximum, as well as the coefficients of variation. Residual values of DOC and DTN were shown to have moderate spatial autocorrelations, and the nugget sill ratios were 0.09% and 0.10%, respectively. Distribution maps revealed that both DOC and DTN concentrations in the study area decreased from the southeast. The variability of both DOC and DTN increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. The cokriging technique performed better than the ordinary kriging for predictions of DOC and DTN, which are highly correlated. This study provides a statistically based assessment of spatial variations in DOC and DTN and identifies the sampling effort required for their accurate quantification, leading to improved assessments of forest ecosystem C and N budgets.



2016 ◽  
Vol 2 (4) ◽  
pp. 165-182 ◽  
Author(s):  
Chelsea L. Petrenko ◽  
Julia Bradley-Cook ◽  
Emily M. Lacroix ◽  
Andrew J. Friedland ◽  
Ross A. Virginia

Shrub species are expanding across the Arctic in response to climate change and biotic interactions. Changes in belowground carbon (C) and nitrogen (N) storage are of global importance because Arctic soils store approximately half of global soil C. We collected 10 (60 cm) soil cores each from graminoid- and shrub-dominated soils in western Greenland and determined soil texture, pH, C and N pools, and C:N ratios by depth for the mineral soil. To investigate the relative chemical stability of soil C between vegetation types, we employed a novel sequential extraction method for measuring organo-mineral C pools of increasing bond strength. We found that (i) mineral soil C and N storage was significantly greater under graminoids than shrubs (29.0 ± 1.8 versus 22.5 ± 3.0 kg·C·m−2 and 1.9 ± .12 versus 1.4 ± 1.9 kg·N·m−2), (ii) chemical mechanisms of C storage in the organo-mineral soil fraction did not differ between graminoid and shrub soils, and (iii) weak adsorption to mineral surfaces accounted for 40%–60% of C storage in organo-mineral fractions — a pool that is relatively sensitive to environmental disturbance. Differences in these C pools suggest that rates of C accumulation and retention differ by vegetation type, which could have implications for predicting future soil C pool storage.





2013 ◽  
Vol 10 (6) ◽  
pp. 10229-10269
Author(s):  
J.-F. Exbrayat ◽  
A. J. Pitman ◽  
Q. Zhang ◽  
G. Abramowitz ◽  
Y.-P. Wang

Abstract. Reliable projections of future climate require land–atmosphere carbon (C) fluxes to be represented realistically in Earth System Models. There are several sources of uncertainty in how carbon is parameterized in these models. First, while interactions between the C, nitrogen (N) and phosphorus (P) cycles have been implemented in some models, these lead to diverse changes in land–atmosphere fluxes. Second, while the parameterization of soil organic matter decomposition is similar between models, formulations of the control of the soil physical state on microbial activity vary widely. We address these sources uncertainty by implementing three soil moisture (SMRF) and three soil temperature (STRF) respiration functions in an Earth System Model that can be run with three degrees of biogeochemical nutrient limitation (C-only, C and N, and C and N and P). All 27 possible combinations of a SMRF with a STRF and a biogeochemical mode are equilibrated before transient historical (1850–2005) simulations are performed. As expected, implementing N and P limitation reduces the land carbon sink, transforming some regions from net sinks to net sources over the historical period (1850–2005). Differences in the soil C balance implied by the various SMRFs and STRFs also change the sign of some regional sinks. Further, although the absolute uncertainty in global carbon uptake is reduced, the uncertainty due to the SMRFs and STRFs grows relative to the inter-annual variability in net uptake when N and P limitations are added. We also demonstrate that the equilibrated soil C also depend on the shape of the SMRF and STRF. Equilibration using different STRFs and SMRFs and nutrient limitation generates a six-fold range of global soil C that largely mirrors the range in available (17) CMIP5 models. Simulating the historical change in soil carbon therefore critically depends on the choice of STRF, SMRF and nutrient limitation, as it controls the equilibrated state to which transient conditions are applied. This direct effect of the representation of microbial decomposition in Earth System Models adds to recent concerns on the adequacy of these simple representations of very complex soil carbon processes.



2008 ◽  
Vol 14 (1) ◽  
pp. 57 ◽  
Author(s):  
M. PAASONEN-KIVEKÄS ◽  
M. YLI-HALLA

Previous studies suggest that nitrogen (N) loads from acid sulphate soil (AS soil) catchments in Finland are higher than those from other agricultural catchments. This study seeks to explain this difference by measuring carbon (C) and N profiles in both an AS soil and a neighbouring non AS soil. In Lapua, western Finland, two adjacent fields (Dystric Cambisols), subjected to similar agricultural practices, were analysed to the depth of 240 cm for pH, total C (Ctot), total N (Ntot), NH4 +-N, NO3 --N, sulphur and bulk density. Field A, an AS soil, contained sulfidic materials and 0.9% Ctot below 170 cm, while Field B, not an AS soil, had 0.3% Ctot in the subsoil and no sulfides. In these soils, the groundwater level declined below 200 cm in summer, subjecting the subsoil to oxidation. This study revealed large stocks of Ctot, Ntot, and mineral N in the subsoil, particularly in the AS soil. At 20–240 cm, Field A contained 292 tons of Ctot ha-1 and 25 tons of Ntot ha-1, while Field B had 152 tons of Ctot ha-1 and 11 tons of Ntot ha-1. Field A contained up to 435 kg of mineral N ha-1 in autumn, while in Field B there was only up to 137 kg of mineral N ha-1. In Field A, NH4 +-N dominated strongly, while NO3 --N dominated in Field B. It is suggested that the greater concentration of mineral N in the AS soil is due to 1) a greater stock of total (mineralizable) N and 2) the slower rate of nitrification resulting in substantial NH4 +-N retention on cation exchange sites.;



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