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Volume 70 (2022): Issue 4 (December 2022)

Volume 70 (2022): Issue 3 (September 2022)

Volume 70 (2022): Issue 2 (June 2022)

Volume 70 (2022): Issue 1 (March 2022)

Volume 69 (2021): Issue 4 (December 2021)

Volume 69 (2021): Issue 3 (September 2021)

Volume 69 (2021): Issue 2 (June 2021)

Volume 69 (2021): Issue 1 (March 2021)

Volume 68 (2020): Issue 4 (December 2020)

Volume 68 (2020): Issue 3 (September 2020)

Volume 68 (2020): Issue 2 (June 2020)

Volume 68 (2020): Issue 1 (March 2020)

Volume 67 (2019): Issue 4 (December 2019)

Volume 67 (2019): Issue 3 (September 2019)

Volume 67 (2019): Issue 2 (June 2019)

Volume 67 (2019): Issue 1 (March 2019)

Volume 66 (2018): Issue 4 (December 2018)

Volume 66 (2018): Issue 3 (September 2018)

Volume 66 (2018): Issue 2 (June 2018)

Volume 66 (2018): Issue 1 (March 2018)

Volume 65 (2017): Issue 4 (December 2017)

Volume 65 (2017): Issue 3 (September 2017)

Volume 65 (2017): Issue 2 (June 2017)

Volume 65 (2017): Issue 1 (March 2017)

Volume 64 (2016): Issue 4 (December 2016)

Volume 64 (2016): Issue 3 (September 2016)

Volume 64 (2016): Issue 2 (June 2016)

Volume 64 (2016): Issue 1 (March 2016)

Volume 63 (2015): Issue 4 (December 2015)

Volume 63 (2015): Issue 3 (September 2015)

Volume 63 (2015): Issue 2 (June 2015)

Volume 63 (2015): Issue 1 (March 2015)

Volume 62 (2014): Issue 4 (December 2014)

Volume 62 (2014): Issue 3 (September 2014)

Volume 62 (2014): Issue 2 (June 2014)

Volume 62 (2014): Issue 1 (March 2014)

Volume 61 (2013): Issue 4 (December 2013)

Volume 61 (2013): Issue 3 (September 2013)

Volume 61 (2013): Issue 2 (June 2013)

Volume 61 (2013): Issue 1 (March 2013)

Volume 60 (2012): Issue 4 (December 2012)

Volume 60 (2012): Issue 3 (September 2012)

Volume 60 (2012): Issue 2 (June 2012)

Volume 60 (2012): Issue 1 (March 2012)

Volume 59 (2011): Issue 4 (December 2011)

Volume 59 (2011): Issue 3 (September 2011)

Volume 59 (2011): Issue 2 (June 2011)

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Volume 58 (2010): Issue 4 (December 2010)

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Volume 57 (2009): Issue 4 (December 2009)

Volume 57 (2009): Issue 3 (September 2009)

Volume 57 (2009): Issue 2 (June 2009)

Volume 57 (2009): Issue 1 (March 2009)

Journal Details
Format
Journal
eISSN
1338-4333
First Published
28 Mar 2009
Publication timeframe
4 times per year
Languages
English

Search

Volume 69 (2021): Issue 4 (December 2021)

Journal Details
Format
Journal
eISSN
1338-4333
First Published
28 Mar 2009
Publication timeframe
4 times per year
Languages
English

Search

11 Articles
Open Access

Biological factors impacting hydrological processes: Pecularities of plants and biological soil crusts

Published Online: 15 Nov 2021
Page range: 357 - 359

Abstract

Open Access

The role of biocrust-induced exopolymeric matrix in runoff generation in arid and semiarid zones – a mini review

Published Online: 15 Nov 2021
Page range: 360 - 368

Abstract

Abstract

Although playing an important role in shaping the environment, the mechanisms responsible for runoff initiation and yield in arid and semiarid regions are not yet fully explored. With infiltration-excess overland flow, known also as Hortonian overland flow (HOF) taking place in these areas, the uppermost surface ‘skin’ plays a cardinal role in runoff initiation and yield. Over large areas, this skin is composed of biocrusts, a variety of autotrophs (principally cyanobacteria, green algae, lichens, mosses) accompanied by heterotrophs (such as fungi, bacteria, archaea), which may largely dictate the infiltration capability of the surface. With most biocrust organisms being capable of excreting extracellular polymeric substances (EPS or exopolymers), and growing evidence pointing to the capability of certain EPS to partially seal the surface, EPS may play a cardinal role in hindering infiltration and triggering HOF. Yet, despite this logic thread, great controversy still exists regarding the main mechanisms responsible for runoff generation (runoff initiation and yield). Elucidation of the possible role played by EPS in runoff generation is the focus of the current review.

Keywords

  • Biological soil crusts
  • Extracellular polymeric substances
  • Pore clogging
  • Hydrophobicity
  • Infiltration-excess overland flow
  • Water repellency
Open Access

Water repellency decreases with increasing carbonate content and pH for different biocrust types on sand dunes

Published Online: 15 Nov 2021
Page range: 369 - 377

Abstract

Abstract

Biocrusts are biological communities that occupy the soil surface, accumulate organic matter and mineral particles and hence strongly affect the properties of the soils they cover. Moreover, by affecting water repellency, biocrusts may cause a preferential infiltration of rainwater, with a high impact on the formation of local water pathways, especially for sand dunes. The aim of this study is to shed light on the connections between water repellency and pH, carbonate and organic matter content in two dune ecosystems with different biocrust types. For this, we used contact angle measurements, gas volumetric carbonate determination and organic matter characterization via FT-IR and TOF-SIMS. In both ecosystems, moss-dominated biocrusts showed higher water repellency and higher amounts of organic matter compared to algal or cyanobacterial biocrusts. Surprisingly, the biocrusts of the two dune systems did not show differences in organic matter composition or organic coatings of the mineral grains. Biocrusts on the more acidic dunes showed a significantly higher level of water repellency as compared to higher carbonate containing dunes. We conclude that the driving factor for the increase in water repellency between cyanobacterial and moss-dominated biocrusts within one study site is the content of organic matter. However, when comparing the different study sites, we found that higher amounts of carbonate reduced biocrust water repellency.

Keywords

  • Organic matter composition
  • Surface characteristics
  • TOF-SIMS
  • Biocrust
  • Carbonate content
  • Water repellency
Open Access

Biocrust effects on soil infiltrability in the Mu Us Desert: Soil hydraulic properties analysis and modeling

Published Online: 15 Nov 2021
Page range: 378 - 386

Abstract

Abstract

The presence of biocrusts changes water infiltration in the Mu Us Desert. Knowledge of the hydraulic properties of biocrusts and parameterization of soil hydraulic properties are important to improve simulation of infiltration and soil water dynamics in vegetation-soil-water models. In this study, four treatments, including bare land with sporadic cyanobacterial biocrusts (BL), lichen-dominated biocrusts (LB), early-successional moss biocrusts (EMB), and late-successional moss biocrusts (LMB), were established to evaluate the effects of biocrust development on soil water infiltration in the Mu Us Desert, northwest of China. Moreover, a combined Wooding inverse approach was used for the estimation of soil hydraulic parameters. The results showed that infiltration rate followed the pattern BL > LB > EMB > LMB. Moreover, the LB, EMB, and LMB treatments had significantly lower infiltration rates than the BL treatment. The saturated soil moisture (θs) and shape parameter (αVG) for the EMB and LMB treatments were higher than that for the BL and LB treatments, although the difference among four treatments was insignificant. Water retention increased with biocrust development at high-pressure heads, whereas the opposite was observed at low-pressure heads. The development of biocrusts influences van Genuchten parameters, subsequently affects the water retention curve, and thereby alters available water in the biocrust layer. The findings regarding the parameterization of soil hydraulic properties have important implications for the simulation of eco-hydrological processes in dryland ecosystems.

Keywords

  • Cyanobacteria
  • Lichen
  • Moss
  • Infiltration
  • Inverse approach
  • Hydraulic parameter
Open Access

Defining minimum runoff length allows for discriminating biocrusts and rainfall events

Published Online: 15 Nov 2021
Page range: 387 - 399

Abstract

Abstract

The runoff coefficient (RC) is widely used despite requiring to know the effective contributing area, which cannot be known a priori. In a previous work, we defined runoff length (RL), which is difficult to measure. This work aimed to define the minimum RL (mRL), a quantitative and easy proxy of RL, for use in a pilot study on biocrusts in the Tabernas Desert, Spain. We show that RC decreases according to a hyperbola when the contributing area increases, the independent variable being the length of the effective contributing area and its coefficient involving the effects of rainfall and surface features and antecedent conditions. We defined the mRL as the length of the effective contributing area making RC = 1, which is calculated regardless of the area. We studied mRL from three biocrust types and 1411 events clustered in seven categories. The mRL increased with rain volume and intensity, catchment area and slope, whereas plant cover and biocrust succession (with one exception) had a negative effect. Depending on the plot, mRL reached up 3.3–4.0 m on cyanobacterial biocrust, 2.2–7.5 m on the most widespread lichens, and 1.0–1.5 m on late-successional lichens. We discuss the relationships of mRL with other runoff-related parameters.

Keywords

  • Semiarid
  • Biological soil crust
  • Runoff connectivity
  • Length slope factor
  • Infiltration
  • Tabernas Desert
Open Access

Mapping past, present and future dew and rain water resources for biocrust evolution in southern Africa

Published Online: 15 Nov 2021
Page range: 400 - 420

Abstract

Abstract

Biocrust sustainability relies on dew and rain availability. A study of dew and rain resources in amplitude and frequency and their evolution is presented from year 2001 to 2020 in southern Africa (Namibia, Botswana, South Africa) where many biocrust sites have been identified. The evaluation of dew is made from a classical energy balance model using meteorological data collected in 18 stations, where are also collected rain data. One observes a strong correlation between the frequency of dew and rain and the corresponding amplitudes. There is a general tendency to see a decrease in dew yield and dew frequency with increasing distance from the oceans, located west, east and south, due to decreasing RH, with a relative minimum in the desert of Kalahari (Namibia). Rain amplitude and frequency decreases when going to west and north. Short-term dew/rain correlation shows that largest dew yields clearly occur during about three days after rainfall, particularly in the sites where humidity is less.

The evolution in the period corresponds to a decrease of rain precipitations and frequency, chiefly after 2010, an effect which has been cyclic since now. The effect is more noticeable towards north. An increase of dew yield and frequency is observed, mainly in north and south-east. It results in an increase of the dew contribution with respect to rain, especially after 2010. As no drastic changes in the distribution of biomass of biocrusts have been reported in this period, it is likely that dew should compensate for the decrease in rain precipitation. Since the growth of biocrust is related to dew and rain amplitude and frequency, future evolution should be characterized by either the rain cycle or, due to global change, an acceleration of the present tendency, with more dew and less rainfalls.

Keywords

  • Biocrust
  • Dew and rain evolution
  • Dew/rain ratio
  • Dew/rain correlation
  • Southern Africa
  • Climate change
Open Access

Water’s path from moss to soil: A multi-methodological study on water absorption and evaporation of soil-moss combinations

Published Online: 15 Nov 2021
Page range: 421 - 435

Abstract

Abstract

Mosses are often overlooked; however, they are important for soil-atmosphere interfaces with regard to water exchange. This study investigated the influence of moss structural traits on maximum water storage capacities (WSCmax) and evaporation rates, and species-specific effects on water absorption and evaporation patterns in moss layers, moss-soil-interfaces and soil substrates using biocrust wetness probes. Five moss species typical for Central European temperate forests were selected: field-collected Brachythecium rutabulum, Eurhynchium striatum, Oxyrrhynchium hians and Plagiomnium undulatum; and laboratory-cultivated Amblystegium serpens and Oxyrrhynchium hians.

WSCmax ranged from 14.10 g g−1 for Amblystegium serpens (Lab) to 7.31 g g−1 for Plagiomnium undulatum when immersed in water, and 11.04 g g−1 for Oxyrrhynchium hians (Lab) to 7.90 g g−1 for Oxyrrhynchium hians when sprayed, due to different morphologies depending on the growing location. Structural traits such as high leaf frequencies and small leaf areas increased WSCmax. In terms of evaporation, leaf frequency displayed a positive correlation with evaporation, while leaf area index showed a negative correlation. Moisture alterations during watering and desiccation were largely controlled by species/substrate-specific patterns. Generally, moss cover prevented desiccation of soil surfaces and was not a barrier to infiltration. To understand water’s path from moss to soil, this study made a first contribution.

Keywords

  • Biological soil crusts
  • Bryophytes
  • Ecohydrology
  • Moss structure
  • Moss hydrology
  • Rainfall interception
Open Access

Effect of mature spruce forest on canopy interception in subalpine conditions during three growing seasons

Published Online: 15 Nov 2021
Page range: 436 - 446

Abstract

Abstract

The interception process in subalpine Norway spruce stands plays an important role in the distribution of throughfall. The natural mountain spruce forest where our measurements of throughfall and gross precipitation were carried out, is located on the tree line at an elevation of 1,420 m a.s.l. in the Western Tatra Mountains (Slovakia, Central Europe). This paper presents an evaluation of the interception process in a natural mature spruce stand during the growing season from May to October in 2018–2020. We also analyzed the daily precipitation events within each growing season and assigned to them individual synoptic types. The amount and distribution of precipitation during the growing season plays an important role in the precipitation-interception process, which confirming the evaluation of individual synoptic situations. During the monitored growing seasons, precipitation was normal (2018), sub-normal (2019) and above-normal (2020) in comparison with long-term precipitation (1988–2017). We recorded the highest precipitation in the normal and above-normal precipitation years during the north-eastern cyclonic synoptic situation (NEc). During these two periods, interception showed the lowest values in the dripping zone at the crown periphery, while in the precipitation sub-normal period (2019), the lowest interception was reached by the canopy gap. In the central crown zone near the stem, interception reached the highest value in each growing season. In the evaluated vegetation periods, interception reached values in the range of 19.6–24.1% of gross precipitation total in the canopy gap, 8.3–22.2% in the dripping zone at the crown periphery and 45.7–51.6% in the central crown zone near the stem. These regimes are expected to change in the Western Tatra Mts., as they have been affected by windstorms and insect outbreaks in recent decades. Under disturbance regimes, changes in interception as well as vegetation, at least for some period of time, are unavoidable.

Keywords

  • Precipitation
  • Interception
  • Synoptic types
  • Norway spruce ( L. Karst.)
  • Growing season
Open Access

Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils

Published Online: 15 Nov 2021
Page range: 447 - 455

Abstract

Abstract

Soil water repellency (SWR) reduces the rates of wetting in dry soils and is known to interfere with water movement into as well as within the soils. The objective of this study was to investigate the hydrophysical characteristics of three water-repellent tropical exotic plantation forest soils in wet and dry seasons. The study sites were Eucalyptus grandis (EG), Pinus caribaea (PC), and Casuarina equisetifolia (CE) plantation forest soils located in the up-country intermediate zone (EG and PC), and low-country dry zone (CE). Field experiments were conducted to measure the infiltration rate, unsaturated hydraulic conductivity (k), water sorptivity (SW). Laboratory experiments were conducted to measure the potential SWR and water entry value (hwe). All three soils showed higher SWR in the dry season, where CE soils showed the highest. The EG soils showed the highest SWR in the wet season. Although SWR in all soils decreased with increasing depth in the wet season, only CE soils showed a significant decrease in SWR with soil depth in the dry season. Compared with the wet season, the k(–1 cm) was lower and hwe was higher in the dry season. However, SW did not show a significant difference between wet and dry seasons. Initial infiltration rate and k(–1 cm) showed a negative correlation with contact angle in all three soils. Soils showed positive linear correlations between k(–1 cm) and SW, and negative linear correlations between SW and hwe showing that surface water absorption is related to both subsurface unsaturated water flow and surface water entry pressure. It was clear that the water entry into soils and the subsurface water flow were hindered by the SWR. High water entry values in the dry season predict high potentials for intensified surface runoff and topsoil erosion. Future research will be required on the interactions between soil biology and soil properties such as pore structure that would influence water flow into and within soils.

Keywords

  • Hydrophysical characteristics
  • Water repellency
Open Access

Relation of influencing variables and weather conditions on rainfall partitioning by birch and pine trees

Published Online: 15 Nov 2021
Page range: 456 - 466

Abstract

Abstract

General weather conditions may have a strong influence on the individual elements of the hydrological cycle, an important part of which is rainfall interception. The influence of general weather conditions on this process was analysed, evaluating separately the influence of various variables on throughfall, stemflow, and rainfall interception for a wet (2014), a dry (2015), and an average (2016) year. The analysed data were measured for the case of birch and pine trees at a study site in the city of Ljubljana, Slovenia. The relationship between the components of rainfall partitioning and the influential variables for the selected years was estimated using two statistical models, namely boosted regression trees and random forest. The results of both implemented models complemented each other well, as both indicated the rainfall amount and the number of raindrops as the most influential variables. During the wet year 2014 rainfall duration seems to play an important role, correlating with the previously observed influence of the variables during the wetter leafless period. Similarly, during the dry year 2015, rainfall intensity had a significant influence on rainfall partitioning by the birch tree, again corresponding to the influences observed during the drier leafed period.

Keywords

  • Throughfall
  • Stemflow
  • Rainfall interception
  • Rainfall microstructure
  • Boosted regression trees
  • Random forest
Open Access

Effects of slow and fast pyrolysis biochar on N2O emissions and water availability of two soils with high water-filled pore space

Published Online: 15 Nov 2021
Page range: 467 - 474

Abstract

Abstract

Biochars, depending on the types of feedstocks and technological conditions of pyrolysis, can vary significantly in their properties and, therefore, it is difficult to predict biochar-induced effects on nitrous oxide (N2O) emissions from various soils, their physical properties and water availability. The objectives of this study were (1) to quantify effects of slow pyrolysis biochar (BC) and fast pyrolysis biochar (PYRO) on physical and hydro-physical properties of sandy soil (Haplic Arenosol) and clayey loam soil (Gleyic Fluvisol), and (2) to assess corresponding N2O emissions from these two soils. The study included a 63-day long laboratory investigation. Two doses of BC or PYRO (15 t ha−1 and 30 t ha−1) were applied to the soils in combination or without nitrogen fertilizer (NH4NO3, 90 kg N ha−1). The obtained results have shown a significant decrease in the bulk density of sandy soil after it was amended with either rate of BC or PYRO. Water retention capacity of the soils in all the treatments with BC or PYRO increased considerably although no changes was found in the soil water-filled pore space (WFPS) which was higher than 60%. BC was increasing N2O emission rates from the sandy soil treated with N fertilizer, and reducing N2O emission rates from the clayey loam soil treated with N fertilizer. PYRO was more efficient and was reducing N2O emissions from both fertilized soils, but for the sandy soil the reduction was statistically significant only at higher dose (30 t ha−1) of the biochar.

Keywords

  • Biochar
  • Sandy soil
  • Clayey loam soil
  • Bulk density
  • Water retention capacity
  • NO emission
11 Articles
Open Access

Biological factors impacting hydrological processes: Pecularities of plants and biological soil crusts

Published Online: 15 Nov 2021
Page range: 357 - 359

Abstract

Open Access

The role of biocrust-induced exopolymeric matrix in runoff generation in arid and semiarid zones – a mini review

Published Online: 15 Nov 2021
Page range: 360 - 368

Abstract

Abstract

Although playing an important role in shaping the environment, the mechanisms responsible for runoff initiation and yield in arid and semiarid regions are not yet fully explored. With infiltration-excess overland flow, known also as Hortonian overland flow (HOF) taking place in these areas, the uppermost surface ‘skin’ plays a cardinal role in runoff initiation and yield. Over large areas, this skin is composed of biocrusts, a variety of autotrophs (principally cyanobacteria, green algae, lichens, mosses) accompanied by heterotrophs (such as fungi, bacteria, archaea), which may largely dictate the infiltration capability of the surface. With most biocrust organisms being capable of excreting extracellular polymeric substances (EPS or exopolymers), and growing evidence pointing to the capability of certain EPS to partially seal the surface, EPS may play a cardinal role in hindering infiltration and triggering HOF. Yet, despite this logic thread, great controversy still exists regarding the main mechanisms responsible for runoff generation (runoff initiation and yield). Elucidation of the possible role played by EPS in runoff generation is the focus of the current review.

Keywords

  • Biological soil crusts
  • Extracellular polymeric substances
  • Pore clogging
  • Hydrophobicity
  • Infiltration-excess overland flow
  • Water repellency
Open Access

Water repellency decreases with increasing carbonate content and pH for different biocrust types on sand dunes

Published Online: 15 Nov 2021
Page range: 369 - 377

Abstract

Abstract

Biocrusts are biological communities that occupy the soil surface, accumulate organic matter and mineral particles and hence strongly affect the properties of the soils they cover. Moreover, by affecting water repellency, biocrusts may cause a preferential infiltration of rainwater, with a high impact on the formation of local water pathways, especially for sand dunes. The aim of this study is to shed light on the connections between water repellency and pH, carbonate and organic matter content in two dune ecosystems with different biocrust types. For this, we used contact angle measurements, gas volumetric carbonate determination and organic matter characterization via FT-IR and TOF-SIMS. In both ecosystems, moss-dominated biocrusts showed higher water repellency and higher amounts of organic matter compared to algal or cyanobacterial biocrusts. Surprisingly, the biocrusts of the two dune systems did not show differences in organic matter composition or organic coatings of the mineral grains. Biocrusts on the more acidic dunes showed a significantly higher level of water repellency as compared to higher carbonate containing dunes. We conclude that the driving factor for the increase in water repellency between cyanobacterial and moss-dominated biocrusts within one study site is the content of organic matter. However, when comparing the different study sites, we found that higher amounts of carbonate reduced biocrust water repellency.

Keywords

  • Organic matter composition
  • Surface characteristics
  • TOF-SIMS
  • Biocrust
  • Carbonate content
  • Water repellency
Open Access

Biocrust effects on soil infiltrability in the Mu Us Desert: Soil hydraulic properties analysis and modeling

Published Online: 15 Nov 2021
Page range: 378 - 386

Abstract

Abstract

The presence of biocrusts changes water infiltration in the Mu Us Desert. Knowledge of the hydraulic properties of biocrusts and parameterization of soil hydraulic properties are important to improve simulation of infiltration and soil water dynamics in vegetation-soil-water models. In this study, four treatments, including bare land with sporadic cyanobacterial biocrusts (BL), lichen-dominated biocrusts (LB), early-successional moss biocrusts (EMB), and late-successional moss biocrusts (LMB), were established to evaluate the effects of biocrust development on soil water infiltration in the Mu Us Desert, northwest of China. Moreover, a combined Wooding inverse approach was used for the estimation of soil hydraulic parameters. The results showed that infiltration rate followed the pattern BL > LB > EMB > LMB. Moreover, the LB, EMB, and LMB treatments had significantly lower infiltration rates than the BL treatment. The saturated soil moisture (θs) and shape parameter (αVG) for the EMB and LMB treatments were higher than that for the BL and LB treatments, although the difference among four treatments was insignificant. Water retention increased with biocrust development at high-pressure heads, whereas the opposite was observed at low-pressure heads. The development of biocrusts influences van Genuchten parameters, subsequently affects the water retention curve, and thereby alters available water in the biocrust layer. The findings regarding the parameterization of soil hydraulic properties have important implications for the simulation of eco-hydrological processes in dryland ecosystems.

Keywords

  • Cyanobacteria
  • Lichen
  • Moss
  • Infiltration
  • Inverse approach
  • Hydraulic parameter
Open Access

Defining minimum runoff length allows for discriminating biocrusts and rainfall events

Published Online: 15 Nov 2021
Page range: 387 - 399

Abstract

Abstract

The runoff coefficient (RC) is widely used despite requiring to know the effective contributing area, which cannot be known a priori. In a previous work, we defined runoff length (RL), which is difficult to measure. This work aimed to define the minimum RL (mRL), a quantitative and easy proxy of RL, for use in a pilot study on biocrusts in the Tabernas Desert, Spain. We show that RC decreases according to a hyperbola when the contributing area increases, the independent variable being the length of the effective contributing area and its coefficient involving the effects of rainfall and surface features and antecedent conditions. We defined the mRL as the length of the effective contributing area making RC = 1, which is calculated regardless of the area. We studied mRL from three biocrust types and 1411 events clustered in seven categories. The mRL increased with rain volume and intensity, catchment area and slope, whereas plant cover and biocrust succession (with one exception) had a negative effect. Depending on the plot, mRL reached up 3.3–4.0 m on cyanobacterial biocrust, 2.2–7.5 m on the most widespread lichens, and 1.0–1.5 m on late-successional lichens. We discuss the relationships of mRL with other runoff-related parameters.

Keywords

  • Semiarid
  • Biological soil crust
  • Runoff connectivity
  • Length slope factor
  • Infiltration
  • Tabernas Desert
Open Access

Mapping past, present and future dew and rain water resources for biocrust evolution in southern Africa

Published Online: 15 Nov 2021
Page range: 400 - 420

Abstract

Abstract

Biocrust sustainability relies on dew and rain availability. A study of dew and rain resources in amplitude and frequency and their evolution is presented from year 2001 to 2020 in southern Africa (Namibia, Botswana, South Africa) where many biocrust sites have been identified. The evaluation of dew is made from a classical energy balance model using meteorological data collected in 18 stations, where are also collected rain data. One observes a strong correlation between the frequency of dew and rain and the corresponding amplitudes. There is a general tendency to see a decrease in dew yield and dew frequency with increasing distance from the oceans, located west, east and south, due to decreasing RH, with a relative minimum in the desert of Kalahari (Namibia). Rain amplitude and frequency decreases when going to west and north. Short-term dew/rain correlation shows that largest dew yields clearly occur during about three days after rainfall, particularly in the sites where humidity is less.

The evolution in the period corresponds to a decrease of rain precipitations and frequency, chiefly after 2010, an effect which has been cyclic since now. The effect is more noticeable towards north. An increase of dew yield and frequency is observed, mainly in north and south-east. It results in an increase of the dew contribution with respect to rain, especially after 2010. As no drastic changes in the distribution of biomass of biocrusts have been reported in this period, it is likely that dew should compensate for the decrease in rain precipitation. Since the growth of biocrust is related to dew and rain amplitude and frequency, future evolution should be characterized by either the rain cycle or, due to global change, an acceleration of the present tendency, with more dew and less rainfalls.

Keywords

  • Biocrust
  • Dew and rain evolution
  • Dew/rain ratio
  • Dew/rain correlation
  • Southern Africa
  • Climate change
Open Access

Water’s path from moss to soil: A multi-methodological study on water absorption and evaporation of soil-moss combinations

Published Online: 15 Nov 2021
Page range: 421 - 435

Abstract

Abstract

Mosses are often overlooked; however, they are important for soil-atmosphere interfaces with regard to water exchange. This study investigated the influence of moss structural traits on maximum water storage capacities (WSCmax) and evaporation rates, and species-specific effects on water absorption and evaporation patterns in moss layers, moss-soil-interfaces and soil substrates using biocrust wetness probes. Five moss species typical for Central European temperate forests were selected: field-collected Brachythecium rutabulum, Eurhynchium striatum, Oxyrrhynchium hians and Plagiomnium undulatum; and laboratory-cultivated Amblystegium serpens and Oxyrrhynchium hians.

WSCmax ranged from 14.10 g g−1 for Amblystegium serpens (Lab) to 7.31 g g−1 for Plagiomnium undulatum when immersed in water, and 11.04 g g−1 for Oxyrrhynchium hians (Lab) to 7.90 g g−1 for Oxyrrhynchium hians when sprayed, due to different morphologies depending on the growing location. Structural traits such as high leaf frequencies and small leaf areas increased WSCmax. In terms of evaporation, leaf frequency displayed a positive correlation with evaporation, while leaf area index showed a negative correlation. Moisture alterations during watering and desiccation were largely controlled by species/substrate-specific patterns. Generally, moss cover prevented desiccation of soil surfaces and was not a barrier to infiltration. To understand water’s path from moss to soil, this study made a first contribution.

Keywords

  • Biological soil crusts
  • Bryophytes
  • Ecohydrology
  • Moss structure
  • Moss hydrology
  • Rainfall interception
Open Access

Effect of mature spruce forest on canopy interception in subalpine conditions during three growing seasons

Published Online: 15 Nov 2021
Page range: 436 - 446

Abstract

Abstract

The interception process in subalpine Norway spruce stands plays an important role in the distribution of throughfall. The natural mountain spruce forest where our measurements of throughfall and gross precipitation were carried out, is located on the tree line at an elevation of 1,420 m a.s.l. in the Western Tatra Mountains (Slovakia, Central Europe). This paper presents an evaluation of the interception process in a natural mature spruce stand during the growing season from May to October in 2018–2020. We also analyzed the daily precipitation events within each growing season and assigned to them individual synoptic types. The amount and distribution of precipitation during the growing season plays an important role in the precipitation-interception process, which confirming the evaluation of individual synoptic situations. During the monitored growing seasons, precipitation was normal (2018), sub-normal (2019) and above-normal (2020) in comparison with long-term precipitation (1988–2017). We recorded the highest precipitation in the normal and above-normal precipitation years during the north-eastern cyclonic synoptic situation (NEc). During these two periods, interception showed the lowest values in the dripping zone at the crown periphery, while in the precipitation sub-normal period (2019), the lowest interception was reached by the canopy gap. In the central crown zone near the stem, interception reached the highest value in each growing season. In the evaluated vegetation periods, interception reached values in the range of 19.6–24.1% of gross precipitation total in the canopy gap, 8.3–22.2% in the dripping zone at the crown periphery and 45.7–51.6% in the central crown zone near the stem. These regimes are expected to change in the Western Tatra Mts., as they have been affected by windstorms and insect outbreaks in recent decades. Under disturbance regimes, changes in interception as well as vegetation, at least for some period of time, are unavoidable.

Keywords

  • Precipitation
  • Interception
  • Synoptic types
  • Norway spruce ( L. Karst.)
  • Growing season
Open Access

Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils

Published Online: 15 Nov 2021
Page range: 447 - 455

Abstract

Abstract

Soil water repellency (SWR) reduces the rates of wetting in dry soils and is known to interfere with water movement into as well as within the soils. The objective of this study was to investigate the hydrophysical characteristics of three water-repellent tropical exotic plantation forest soils in wet and dry seasons. The study sites were Eucalyptus grandis (EG), Pinus caribaea (PC), and Casuarina equisetifolia (CE) plantation forest soils located in the up-country intermediate zone (EG and PC), and low-country dry zone (CE). Field experiments were conducted to measure the infiltration rate, unsaturated hydraulic conductivity (k), water sorptivity (SW). Laboratory experiments were conducted to measure the potential SWR and water entry value (hwe). All three soils showed higher SWR in the dry season, where CE soils showed the highest. The EG soils showed the highest SWR in the wet season. Although SWR in all soils decreased with increasing depth in the wet season, only CE soils showed a significant decrease in SWR with soil depth in the dry season. Compared with the wet season, the k(–1 cm) was lower and hwe was higher in the dry season. However, SW did not show a significant difference between wet and dry seasons. Initial infiltration rate and k(–1 cm) showed a negative correlation with contact angle in all three soils. Soils showed positive linear correlations between k(–1 cm) and SW, and negative linear correlations between SW and hwe showing that surface water absorption is related to both subsurface unsaturated water flow and surface water entry pressure. It was clear that the water entry into soils and the subsurface water flow were hindered by the SWR. High water entry values in the dry season predict high potentials for intensified surface runoff and topsoil erosion. Future research will be required on the interactions between soil biology and soil properties such as pore structure that would influence water flow into and within soils.

Keywords

  • Hydrophysical characteristics
  • Water repellency
Open Access

Relation of influencing variables and weather conditions on rainfall partitioning by birch and pine trees

Published Online: 15 Nov 2021
Page range: 456 - 466

Abstract

Abstract

General weather conditions may have a strong influence on the individual elements of the hydrological cycle, an important part of which is rainfall interception. The influence of general weather conditions on this process was analysed, evaluating separately the influence of various variables on throughfall, stemflow, and rainfall interception for a wet (2014), a dry (2015), and an average (2016) year. The analysed data were measured for the case of birch and pine trees at a study site in the city of Ljubljana, Slovenia. The relationship between the components of rainfall partitioning and the influential variables for the selected years was estimated using two statistical models, namely boosted regression trees and random forest. The results of both implemented models complemented each other well, as both indicated the rainfall amount and the number of raindrops as the most influential variables. During the wet year 2014 rainfall duration seems to play an important role, correlating with the previously observed influence of the variables during the wetter leafless period. Similarly, during the dry year 2015, rainfall intensity had a significant influence on rainfall partitioning by the birch tree, again corresponding to the influences observed during the drier leafed period.

Keywords

  • Throughfall
  • Stemflow
  • Rainfall interception
  • Rainfall microstructure
  • Boosted regression trees
  • Random forest
Open Access

Effects of slow and fast pyrolysis biochar on N2O emissions and water availability of two soils with high water-filled pore space

Published Online: 15 Nov 2021
Page range: 467 - 474

Abstract

Abstract

Biochars, depending on the types of feedstocks and technological conditions of pyrolysis, can vary significantly in their properties and, therefore, it is difficult to predict biochar-induced effects on nitrous oxide (N2O) emissions from various soils, their physical properties and water availability. The objectives of this study were (1) to quantify effects of slow pyrolysis biochar (BC) and fast pyrolysis biochar (PYRO) on physical and hydro-physical properties of sandy soil (Haplic Arenosol) and clayey loam soil (Gleyic Fluvisol), and (2) to assess corresponding N2O emissions from these two soils. The study included a 63-day long laboratory investigation. Two doses of BC or PYRO (15 t ha−1 and 30 t ha−1) were applied to the soils in combination or without nitrogen fertilizer (NH4NO3, 90 kg N ha−1). The obtained results have shown a significant decrease in the bulk density of sandy soil after it was amended with either rate of BC or PYRO. Water retention capacity of the soils in all the treatments with BC or PYRO increased considerably although no changes was found in the soil water-filled pore space (WFPS) which was higher than 60%. BC was increasing N2O emission rates from the sandy soil treated with N fertilizer, and reducing N2O emission rates from the clayey loam soil treated with N fertilizer. PYRO was more efficient and was reducing N2O emissions from both fertilized soils, but for the sandy soil the reduction was statistically significant only at higher dose (30 t ha−1) of the biochar.

Keywords

  • Biochar
  • Sandy soil
  • Clayey loam soil
  • Bulk density
  • Water retention capacity
  • NO emission

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