Spatial Variability of Soil Surface Properties and Consequences for the Annual and Monthly Water Balance of a Semiarid Environment (EFEDA Experiment)

Abstract. One fourth (5.5 Mha) of forests in Finland are growing on peatlands that have been drained to improve forest growth. Forestry operations such as cuttings and ditch network maintenance in these areas may increase export of suspended solids and nutrients, and deteriorate water quality in receiving lakes and rivers. Mitigation of the deterioration calls for understanding how forest management operations affect peatland hydrology. A process-based simulation model FEMMA was applied to quantify the effects of ditch network maintenance on peatland water balance. The model has separate computation routines for evapotranspiration in tree stand and understorey vegetation, snow accumulation and melt, water movement in unsaturated and saturated soil, and drainage. Hydraulic characteristics of peat, as well as different drainage designs can be parameterised in the model. The model was applied in artificially delineated research catchments in northern Finland, where the ditch network was maintained by cleaning and digging the ditches deeper. The simulation results indicated that ditch cleaning affected the water balance slightly and the effect was dependent on stand characteristics and soil structure. When the growing stock volume was low and poorly conductive soil extended close to the soil surface, ditch cleaning increased evapotranspiration. In stands with a high stock volume and a thick topmost layer of highly conductive soil, evapotranspiration was less affected. In the study catchments, the effect of ditch cleaning on runoff was small compared to the error between measured and modelled runoff.

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Impact of Spatial Variability on Transport of Pesticides From Soil Surface to Pumping Well

Soil & Environment - Integrated Soil and Sediment Research: A Basis for Proper Protection ◽

10.1007/978-94-011-2008-1_92 ◽

1993 ◽

pp. 441-444

Author(s):

W. H. J. Beltman ◽

J. J. T. I. Boesten ◽

S. E. A. T. M. Zee

Keyword(s):

Spatial Variability ◽

Soil Surface

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Localized basal area affects soil respiration temperature sensitivity in a coastal deciduous forest

Biogeosciences ◽

10.5194/bg-17-771-2020 ◽

2020 ◽

Vol 17 (3) ◽

pp. 771-780 ◽

Cited By ~ 1

Author(s):

Stephanie C. Pennington ◽

Nate G. McDowell ◽

J. Patrick Megonigal ◽

James C. Stegen ◽

Ben Bond-Lamberty

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Spatial Variability ◽

Temperature Sensitivity ◽

Large Scale ◽

Deciduous Forest ◽

Basal Area ◽

Soil Surface ◽

Study Sites ◽

Positive Effect

Abstract. Soil respiration (Rs), the flow of CO2 from the soil surface to the atmosphere, is one of the largest carbon fluxes in the terrestrial biosphere. The spatial variability of Rs is both large and poorly understood, limiting our ability to robustly scale it in space. One factor in Rs spatial variability is the autotrophic contribution from plant roots, but it is uncertain how the presence of plants affects the magnitude and temperature sensitivity of Rs. This study used 1 year of Rs measurements to examine the effect of localized basal area on Rs in the growing and dormant seasons, as well as during moisture-limited times, in a temperate, coastal, deciduous forest in eastern Maryland, USA. In a linear mixed-effects model, tree basal area within a 5 m radius (BA5) exerted a significant positive effect on the temperature sensitivity of soil respiration. Soil moisture was the dominant control on Rs during the dry portions of the year, while soil moisture, temperature, and BA5 all exerted significant effects on Rs in wetter periods. Our results suggest that autotrophic respiration is more sensitive to temperature than heterotrophic respiration at these sites, although we did not measure these source fluxes directly, and that soil respiration is highly moisture sensitive, even in a record-rainfall year. The Rs flux magnitudes (0.46–15.0 µmol m−2 s−1) and variability (coefficient of variability 10 %–23 % across plots) observed in this study were comparable to values observed in similar forests. Six Rs observations would be required in order to estimate the mean across all study sites to within 50 %, and 518 would be required in order to estimate it to within 5 %, with 95 % confidence. A better understanding of the spatial interactions between plants and microbes, as well as the strength and speed of above- and belowground coupling, is necessary to link these processes with large-scale soil-to-atmosphere C fluxes.

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Grassland fire effect on soil organic carbon reservoirs in a semiarid environment

Solid Earth ◽

10.5194/se-4-381-2013 ◽

2013 ◽

Vol 4 (2) ◽

pp. 381-385 ◽

Cited By ~ 26

Author(s):

A. Novara ◽

L. Gristina ◽

J. Rühl ◽

S. Pasta ◽

G. D'Angelo ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Vegetation Type ◽

Soil Surface ◽

Dry Weight ◽

Grassland Management ◽

Semiarid Environment ◽

Significant Difference ◽

Before And After ◽

Grassland Fire

Abstract. The aim of this work was to investigate the effect of an experimental fire used for grassland management on soil organic carbon (SOC) stocks. The study was carried out on Hyparrhenia hirta (L.) Stapf (Hh) grassland and Ampelodesmos mauritanicus (Desf.) T. Durand & Schinz (Am) grasslands located in the north of Sicily. Soil samples were collected at 0–5 cm before and after the experimental fire, and SOC was measured. During the grassland fire, soil surface temperature was monitored. Biomass of both grasses was analysed in order to determine dry weight and its chemical composition. The results showed that SOC varied significantly with vegetation type, while it is not affected in the short term by grassland fire. Am grassland stored more SOC compared with Hh grassland thanks to lower content in the biomass of the labile carbon pool. No significant difference was observed in SOC before and after fire, which could be caused by several factors: first, in both grassland types the measured soil temperature during fire was low due to thin litter layers; second, in a semiarid environment, a higher mineralization rate results in a lower soil carbon labile pool; and third, the SOC stored in the finest soil fractions, physically protected, is not affected by fire.

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