scholarly journals SOIL DRYNESS AND ITS EFFECT ON TOXIC COPPER MOBILITY

2021 ◽  
Author(s):  
Hossam Altaher ◽  
Andrea Dietrich ◽  
John Novak
Keyword(s):  
Soil Dryness

scholarly journals Changes in Lightning Fire Incidence in the Tasmanian Wilderness World Heritage Area, 1980–2016

Fire ◽  
2018 ◽  
Vol 1 (3) ◽  
pp. 38 ◽  
Author(s):  
Jenny Styger ◽  
Jon Marsden-Smedley ◽  
Jamie Kirkpatrick
Keyword(s):  
Cultural Values ◽  
Fire Regimes ◽  
World Heritage ◽  
Fuel Load ◽  
Lightning Strike ◽  
Lightning Strikes ◽  
World Heritage Area ◽  
Soil Dryness ◽  
Heritage Area ◽  
Fire Incidence

The Tasmanian Wilderness World Heritage Area (TWWHA) has globally significant natural and cultural values, some of which are dependent on the absence of fire or the presence of particular fire regimes. Planned burning is currently used to reduce the risk of loss of world heritage values from unplanned fires, but large and damaging fires still occur, with lightning as the primary ignition source. Lightning-caused fire was rare in the TWWHA before 2000. There has since been an increase in both the number of fires following lightning storms and the area burnt by these fires. In the absence of a direct measurement of lightning strike incidence, we tested whether changes in rainfall, soil dryness and fuel load were responsible for these changes in fire incidence and extent. There were no relationships between these variables and the incidence of fires associated with lightning, but the variability in the Soil Dryness Index and the mean of 25% of driest values did predict both the number and area of fires. Thus, it appears that an increase in the proportion of lightning strikes that occur in dry conditions has increased ignition efficiency. These changes have important implications for the management of the TWWHA’s values, as higher projected fuel loads and drier climates could result in a further increase in the number of fires associated with lightning.

scholarly journals Environmental effects on stem water deficit in co-occurring conifers exposed to soil dryness

2014 ◽  
Vol 59 (4) ◽  
pp. 417-426 ◽  
Author(s):  
Walter Oberhuber ◽  
Werner Kofler ◽  
Roman Schuster ◽  
Gerhard Wieser
Keyword(s):  
Water Deficit ◽  
Environmental Effects ◽  
Stem Water ◽  
Soil Dryness

scholarly journals Temporal dynamics of nonstructural carbohydrates and xylem growth in Pinus sylvestris exposed to drought

2011 ◽  
Vol 41 (8) ◽  
pp. 1590-1597 ◽  
Author(s):  
Walter Oberhuber ◽  
Irene Swidrak ◽  
Daniela Pirkebner ◽  
Andreas Gruber
Keyword(s):  
Pinus Sylvestris ◽  
Temporal Dynamics ◽  
Growing Season ◽  
Cambial Activity ◽  
Wood Formation ◽  
Nonstructural Carbohydrates ◽  
Late Wood ◽  
Structural Growth ◽  
Xylem Growth ◽  
Soil Dryness

Wood formation requires a continuous supply of carbohydrates for structural growth and metabolism. In the montane belt of the central Austrian Alps, we monitored the temporal dynamics of xylem growth and nonstructural carbohydrates (NSC) in stem sapwood of Scots pine ( Pinus sylvestris L.) during the growing season of 2009, which was characterized by exceptional soil dryness within the study area. Soil water content dropped below 10% at the time of maximum xylem growth at the end of May. Histological analyses have been used to describe cambial activity and xylem growth. Determination of NSC was performed using specific enzymatic assays revealing that total NSC ranged from 0.8% to 1.7% dry matter throughout the year. Significant variations (P < 0.05) of the size of the NSC pool were observed during the growing season. Starch showed persistent abundance throughout the year, reaching a maximum shortly before onset of late wood formation in mid-July. Seasonal dynamics of NSC and xylem growth suggest that (i) high sink activity occurred at the start of the growing season in spring and during late wood formation in summer and (ii) there was no particular shortage in NSC, which caused P. sylvestris to draw upon stem reserves more heavily during the drought in 2009.

scholarly journals Long-Term Steady-State Dry Boreal Forest in the Face of Disturbance

Ecosystems ◽  
2019 ◽  
Vol 23 (5) ◽  
pp. 1075-1092 ◽  
Author(s):  
Christopher Carcaillet ◽  
Mireille Desponts ◽  
Vincent Robin ◽  
Yves Bergeron
Keyword(s):  
Steady State ◽  
Boreal Forests ◽  
Pinus Banksiana ◽  
Fire History ◽  
Cenococcum Geophilum ◽  
Natural Fire ◽  
Aeolian Dunes ◽  
The Face ◽  
Original Vegetation ◽  
Soil Dryness

Abstract We used bioproxies from paleosoils buried within two aeolian dunes to test hypotheses concerning the origin of dry sandy boreal forests in Canada. These forests are dominated today by Pinus banksiana Lamb. One hypothesis is that too frequent Holocene stand-replacing fires would have transformed the original vegetation through extirpation of susceptible species to fire in water stress habitat. Alternatively, the ecosystem would have not changed since the dunes stabilized enough to support forest establishment. The vegetation composition and richness were determined by identification of charcoal and macroremains and radiocarbon dating for the chronology. Both sites revealed a similar history covering 6400 years. Half of the charcoal layers were less than 2500 years old in both sites, indicating that they had been subjected to the same fire history. Data indicated a stable plant composition and richness, although the percentage of Pinus decreased slightly over 4000 years (decreasing rate 1% per century). The fungus Cenococcum geophilum was consistently present, with a stochastic abundance. The vegetation grew under natural fire conditions and soil dryness since 6000 years. The ecosystem was probably not stressed by late-Holocene fires or climate changes, as the multi-millennial steady state reveals a resistant and resilient ecosystem.

Prescribed Burning of Thinning Slash in Regrowth Stands of Karri (Eucalyptus diversicolor) .2. Nitrogen Budgets in Pre- and Post-Burn Fuel

1997 ◽  
Vol 7 (1) ◽  
pp. 41 ◽  
Author(s):  
AM O'Connell ◽  
WL McCaw
Keyword(s):  
Prescribed Burning ◽  
Fire Hazard ◽  
Weather Conditions ◽  
Moderate Intensity ◽  
Litter Layer ◽  
Nitrogen Budgets ◽  
Dryness Index ◽  
Soil Dryness ◽  
Fuel Components ◽  
Eucalyptus Diversicolor

Changes in nitrogen content of fuel were investigated following eight low to moderate intensity experimental fires conducted under a range of fire weather conditions in a recently thinned 22-year-old regrowth stand of karri (Eucalyptus diversicolor F. Muell) in Western Australia. The average amount of dead fuel < 100 mm in diameter present before burning was 76 t/ha (range 50 to 107 t/ha). The amount of live fuel was small, with a mean of 4 t/ha. Forest floor litter, consisting of fresh and partly decomposed dead leaves and fine twigs (< 6 mm diameter) contributed about 30% of total fuel weight, and wood fractions > 6 mm in diameter contributed about 60%. Remaining fuel was made up of small twigs, bark and leaves added from the thinning operation. Distribution of nitrogen in fuel fractions differed markedly from distribution of fuel weights with more than 60% of fuel-nitrogen in the litter and only about 25% of fuel-nitrogen in wood greater than 6 mm diameter. Following fire, the average amounts of nitrogen in all fuel fractions was reduced. The majority of nitrogen in wood fractions and in bark and leaves was volatilized during the fires (range 55% to 99%), while on average only about 38% of the nitrogen in litter was volatilized. The amount of nitrogen lost from dead fuel differed between the experimental fires (range 50 to 180 kg/ha) and was significantly related to the total amount of fuel consumed (r2 = 0.92). Fuel consumption and nitrogen volatilization increased as the Soil Dryness Index increased and as litter moisture decreased. Nitrogen losses due to burning were small relative to total stores of nitrogen in soil (about 6000 kg/ha) but for the most intense fires were significant in relation to amounts in growing vegetation and surface soil. Burning when moisture content of the litter profile exceeds 90% will reduce combustion of the litter layer. Burning under these conditions allows effective reduction in the flash fuel components located in the upper parts of the fuel bed while retaining much of the nutrient-rich lower strata of fuel. Burns of this type provide effective fire hazard reduction while favouring conservation of nitrogen stored in the litter layer.

scholarly journals Forcing variables in simulation of transpiration of water stressed plants determined by principal component analysis

2016 ◽  
Vol 30 (4) ◽  
pp. 431-445
Author(s):  
Angelica Durigon ◽  
Quirijn de Jong van Lier ◽  
Klaas Metselaar
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Specific Humidity ◽  
Leaf Angle ◽  
Prediction Errors ◽  
Angle Distribution ◽  
Time Frequency ◽  
Soil Dryness

AbstractTo date, measuring plant transpiration at canopy scale is laborious and its estimation by numerical modelling can be used to assess high time frequency data. When using the model by Jacobs (1994) to simulate transpiration of water stressed plants it needs to be reparametrized. We compare the importance of model variables affecting simulated transpiration of water stressed plants. A systematic literature review was performed to recover existing parameterizations to be tested in the model. Data from a field experiment with common bean under full and deficit irrigation were used to correlate estimations to forcing variables applying principal component analysis. New parameterizations resulted in a moderate reduction of prediction errors and in an increase in model performance. Agsmodel was sensitive to changes in the mesophyll conductance and leaf angle distribution parameterizations, allowing model improvement. Simulated transpiration could be separated in temporal components. Daily, afternoon depression and long-term components for the fully irrigated treatment were more related to atmospheric forcing variables (specific humidity deficit between stomata and air, relative air humidity and canopy temperature). Daily and afternoon depression components for the deficit-irrigated treatment were related to both atmospheric and soil dryness, and long-term component was related to soil dryness.

Can the Deforestation Breeze Change the Rainfall in Amazonia? A Case Study for the BR-163 Highway Region

2010 ◽  
Vol 14 (18) ◽  
pp. 1-25 ◽  
Author(s):  
Sandra I. Saad ◽  
Humberto R. da Rocha ◽  
Maria A. F. Silva Dias ◽  
Rafael Rosolem
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Three Dimensional ◽  
Atmospheric Modeling ◽  
Thermal Cell ◽  
Soil Wetness ◽  
Soil Dryness ◽  
Regional Atmospheric Modeling ◽  
The Impact

Abstract The authors simulated the effects of Amazonian mesoscale deforestation in the boundary layer and in rainfall with the Brazilian Regional Atmospheric Modeling System (BRAMS) model. They found that both the area and shape (with respect to wind incidence) of deforestation and the soil moisture status contributed to the state of the atmosphere during the time scale of several weeks, with distinguishable patterns of temperature, humidity, and rainfall. Deforestation resulted in the development of a three-dimensional thermal cell, the so-called deforestation breeze, slightly shifted downwind to large-scale circulation. The boundary layer was warmer and drier above 1000-m height and was slightly wetter up to 2000-m height. Soil wetness affected the circulation energetics proportionally to the soil dryness (for soil wetness below ∼0.6). The shape of the deforestation controlled the impact on rainfall. The horizontal strips lined up with the prevailing wind showed a dominant increase in rainfall, significant up to about 60 000 km2. On the other hand, in the patches aligned in the opposite direction (north–south), there was both increase and decrease in precipitation in two distinct regions, as a result of clearly separated upward and downward branches, which caused the precipitation to increase for patches up to 15 000 km2. The authors’ estimates for the size of deforestation impacting the rainfall contributed to fill up the low spatial resolution in other previous studies.

scholarly journals Functional Composition Changes of a Subtropical Monsoon Evergreen Broad-Leaved Forest Under Environmental Change

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 191
Author(s):  
Shun Zou ◽  
Qianmei Zhang ◽  
Guoyi Zhou ◽  
Shizhong Liu ◽  
Guowei Chu ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Drought Tolerance ◽  
Species Composition ◽  
Environmental Change ◽  
Subtropical Forest ◽  
Functional Composition ◽  
Composition Change ◽  
Environment Change ◽  
Soil Dryness ◽  
Composition Changes

Long-term studies have revealed that forest species composition was shifting under environment change and disturbance induced by loss of large trees. Yet, few studies explicitly analyzed their impacts on composition concurrently. To learn more about impacts of environment change and disturbance on driving forest community, we investigated shifts in functional composition over past 24 years in an old-growth subtropical forest in southern China. We analyzed nine traits that are mainly related to leaf nutrients, photosynthetic capacity, hydraulic conductivity, and drought tolerance of plants and examined hypotheses: (1) The functional composition change over time was directional instead of random fluctuation, (2) drought-tolerant species increased their abundance under soil dryness, (3) both environmental change and disturbance related to changes of functional composition significantly, and (4) initial trait values of quadrats strongly influenced their subsequent change rates in quadrat level (10 × 10 m). We found that species composition had shifted to favor species with high leaf nutrient content, high photosynthesis rate, high hydraulic conductivity, low water-use efficiency, and high drought tolerance traits, which was due to soil dryness and disturbance. These two factors explained 47–58% of quadrats’ trait value changes together. Considering rapidly increasing stem density, this pattern may indicate ecological processes of which disturbance provided numerous recruits of resource-acquisition strategy species and soil dryness conducted a selecting effect on shaping composition in the forest. Additionally, quadrats with initial trait values at the far end of change direction shifted faster in three traits, which also indicated that functional composition changes in quadrats were directional and homogenized. Our results implied that environment change and accompanied disturbance events possibly drove species composition change along a different trajectory in the subtropical forest that experienced high climatic variability.

Influence of Tillage, Antecedent Moisture, and Rainfall Timing on Atrazine Transport

Weed Science ◽  
1995 ◽  
Vol 43 (1) ◽  
pp. 134-139 ◽  
Author(s):  
Gilbert C. Sigua ◽  
Allan R. Isensee ◽  
Alim. Sadeghi
Keyword(s):  
Pore Volume ◽  
Soil Cores ◽  
Leaching Rate ◽  
Laboratory Studies ◽  
Antecedent Moisture ◽  
No Till ◽  
Time Period ◽  
Soil Dryness ◽  
Intact Soil Cores ◽  
Intact Soil

Laboratory studies were conducted to determine the effect of rainfall timing and antecedent moisture on atrazine leaching through intact soil cores taken from no-till and conventional-till corn fields. Simulated rainfall was applied to no-till and conventional-till cores 1 to 14 d after atrazine application and, in a second study, one d after atrazine was applied to no-till and conventional-till cores at 1 to 800 kPa soil moisture. Increasing the lag time between atrazine application and rainfall from one to 14 d reduced the amount of atrazine leached by about 50% for both no-till and conventional-till soil cores. During the same time period, the amount of atrazine adsorbed to soil increased by about 30% for both tillages. Soil dryness (antecedent moisture) at the time of atrazine application had no effect on the amount of atrazine leached through conventional-till cores. However, leaching decreased in no-till cores as antecedent moisture decreased from 1 to 33 kPa; drying to 800 kPa had no further effect. The leaching rate of atrazine was much higher for the initial 0.5 pore volume than for the next 1.5 pore volume at all rainfall timing and antecedent moisture levels. This behavior is indicative of preferential transport.

scholarly journals CLIMAT ESTIVAL ET DEPERISSEMENT DU BOULEAU A PAPIER

1962 ◽  
Vol 38 (3) ◽  
pp. 327-335 ◽  
Author(s):  
Marcel Lortie ◽  
Rene Pomerleau ◽  
Gerard Michaud
Keyword(s):  
Soil Moisture ◽  
High Temperature ◽  
Soil Temperature ◽  
Critical Level ◽  
White Birch ◽  
Soil Dryness ◽  
Noxious Effect ◽  
Dangerous Point

During a six-year study of the microclimate in relation to the dieback of white birch, periods of high temperature and drought were recorded in 1955 and in 1959. At no time did the soil temperature reach a dangerous point but soil moisture fell to a critical level for short periods. However, no noxious effect that could be traced to temporary soil dryness was noted on the 550 trees under observation.

Sign in / Sign up

Export Citation Format

Share Document