Can old growth alpine forests be biophysical barriers against current heat waves?

2020 ◽  
Author(s):  
Leonardo Montagnani ◽  
Nikolaus Obojes ◽  
Gert Wolf ◽  
Glenda Garcia Santos
Keyword(s):  
Hydrological Cycle ◽  
Heat Waves ◽  
Water Cycle ◽  
Large Fraction ◽  
Water Discharge ◽  
Stand Age ◽  
Relative Role ◽  
Canopy Interception ◽  
Old Growth ◽  
Current Heat

<p><strong>Can old growth alpine forests be biophysical barriers against current heat waves?</strong></p><p>The current climate crisis requires an urgent understanding of ecosystem features dampening and alleviating the increasing radiation forcing. To this end, emission of latent heat from forests emerges with its relevance among the terrestrial ecosystem properties. It is not clear, however, if the different forest structures and ages act similarly, depending on the species composition, or if their structure has a role.</p><p>We performed a research on the hydrological cycle in the highly instrumented research facility in Renon forest, Italian Alps, belonging to the ICOS European infrastructure. The site is covered by a dense but structurally heterogeneous spruce forest, characterized by a young sector, with 30 years trees and an old forest sector composed by 200 years old trees.</p><p>Energy and water balance are quantified by eddy covariance instrumentation, 12 sap flux sensors in trees representative of the forest tree ages and 20 below-canopy pluviometers in each of the two forest structures. With these pluviometers, we quantified the relative role of canopy interception as a function of LAI density, precipitation intensity and duration. Water discharge and fog interception measurements allowed the closure of the water cycle at catchment scale.</p><p>Interestingly, we found that the water cycle is largely decoupled from the ground. In the old forest section, the fraction of water reaching the ground in the old sector is the 0.42±0.17 (vs. 0.67±0.17 in the young sector) of incoming precipitation. This suggests that in old alpine forests the hydrological cycle takes place largely in the crown and the old forest is using a large fraction of precipitation to dissipate heat.</p><p>Our results support the view of stand age as emerging property in the atmosphere-biosphere interaction and highlight the relevance of old forests in dampening the recurrent heat spells spreading across Europe, with the Alps and their remaining old growth forests standing as biophysical barriers.</p>

scholarly journals The effect of vegetation canopy on canopy storage capacity with different rainfall intensity

2018 ◽  
Vol 250 ◽  
pp. 04001
Author(s):  
A.M. Nur Syahida ◽  
A.B. Azinoor Azida
Keyword(s):  
Rainfall Intensity ◽  
Storage Capacity ◽  
Hydrological Cycle ◽  
Water Discharge ◽  
Canopy Cover ◽  
Canopy Interception ◽  
Rainfall Interception ◽  
Barren Land ◽  
Vital Component ◽  
Land Covers

Canopy Interception is one of the vital component in hydrological cycle and underestimating the interception process can significantly affect the water balance. A study of rainfall interception was conducted using rainfall simulator called hydrology apparatus. Three different rainfall intensities were used in this study; 90 mm/hr, 140 mm/hr and 180 mm/hr. These intensities were produced by 8 nozzles. The test were first carried out on the barren land without the existence of canopy cover. To study the effect of canopy cover on canopy storage capacity, broadleaf plant (Scindapsus Aureus) was used to cover the barren land. The differences between the amount of water discharge between these two different land covers were observed to determine the quantity of water stored in the canopy. Results indicated that Scindapsus Aureus intercepted more water at lower intensity than at higher intensity. The lowest intensity was 90 mm/hr stored 1.6mm of rainwater while 140 mm/hr retained 0.8 mm. 180 mm/hr was the highest rainfall intensity used in this study intercepted 0.3mm of total precipitation. Therefore, this study proved that rainfall intensity is one of the main factors that influence the rainfall interception process.

scholarly journals Functional effects of forest ecosystems on water cycle – Slovakia case study

2018 ◽  
Vol 64 (No. 8) ◽  
pp. 331-339
Author(s):  
Minďaš Jozef ◽  
Bartík Martin ◽  
Škvareninová Jana ◽  
Repiský Richard
Keyword(s):  
Forest Ecosystems ◽  
Water Cycle ◽  
Beech Forest ◽  
Stand Age ◽  
Canopy Interception ◽  
Mountain Areas ◽  
Tree Species Composition ◽  
Growing Seasons ◽  
Wide Range ◽  
Interception Loss

The paper presents the results from three different experimental plots in mountain areas in Slovakia. Annual interception losses varied in mature forest stand in Poľana Mts. (850 m a.s.l.) in mixtured (spruce, fir, beech) from 10.6 to 23.5%, in spruce from 20.5 to 35.5% and in beech forest from 8.8 to 26.9%. Horizontal precipitation reduces long-term average of interception loss by 3.2% (mixtured and spruce) and 2.9% for beech forest. Decline process in supramontane spruce forest has significant influence on interception process in climax spruce stand in Červenec. Mean biweekly interception loss in the central crown zone near the stem during growing seasons was 76.9% in living and 69.2% in dead forest. In the gap canopy interception loss was observed 11.7% in living and 17.9% in dead forest, in the dripping zone under the crown periphery 11.1% in living and 25.7% in dead forest. Results from the experimental catchment Lomnistá dolina showed that forest ecosystems increase the variability of rainfall amounts infiltrated to the soil environment in mountain watersheds, interception loss varied in a wide range: from 42 up to –10% due to altitudinal influence, tree species composition, stand age, and horizontal precipitation occurence.

scholarly journals Partitioning the forest water balance within a boreal catchment using sapflux, eddy covariance and process-based model

2019 ◽  
Author(s):  
Natalia Kozii ◽  
Kersti Haahti ◽  
Pantana Tor-ngern ◽  
Jinshu Chi ◽  
Eliza Maher Hasselquist ◽  
...  
Keyword(s):  
Water Balance ◽  
Eddy Covariance ◽  
Water Loss ◽  
Stand Structure ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
Canopy Interception ◽  
Cascading Effects

Abstract. In the hydrological cycle, water is lost from terrestrial ecosystems either laterally through stream runoff or vertically as evapotranspiration (ET) back to the atmosphere. Although it is well known that ET losses represents an important water loss pathway at local to global scales, the magnitude and relative importance of ET and its individual flux components varies considerable among different ecosystems. In this study, we combined empirical sapflux and eddy covariance measurements with estimates from a process-based model to partition the water balance in a boreal forested catchment. This study was conducted within the Krycklan Catchment, which has state-of-the-art infrastructure for hydrological measurements, thereby providing us the unique opportunity to compare the absolute and relative magnitude of ET and its flux components to other water loss pathways (i.e., stream runoff). During the growing season, ET was the major water loss pathway, representing ca. 85 % of the incoming precipitation and being roughly 7 times greater than stream runoff. Both the empirical results and model estimates suggested that tree transpiration (T) and canopy interception (IL) represented 45 % and 35 % of total ET loss; respectively, and thus together were responsible for 70 % of the water loss during the growing season. Understory evapotranspiration (ETu) was less important than T and IL during most of the study period, except for late autumn when ETu was the largest ET flux component. Overall, our study highlights the importance of trees in regulating the water cycle of boreal catchments, implying that forest management impacts on stand structure as well as climate change effects on tree growth are likely to have large cascading effects on the way water moves through these forested landscapes.

scholarly journals Expected changes in water resources availability and water quality with respect to climate change in the Elbe River basin (Germany)

2005 ◽  
Vol 36 (4-5) ◽  
pp. 321-333 ◽  
Author(s):  
Valentina Krysanova ◽  
Fred Hattermann ◽  
Anja Habeck
Keyword(s):  
Climate Change ◽  
Water Quality ◽  
River Basin ◽  
Hydrological Cycle ◽  
Water Discharge ◽  
Regional Scale ◽  
Elbe River ◽  
Elbe River Basin ◽  
The Mean ◽  
The Elbe River

Reliable modelling of climate–water interactions at the river basin and regional scale requires development of advanced modelling approaches at scales relevant for assessing the potential effects of climate change on the hydrological cycle. These approaches should represent the atmospheric, surface and subsurface hydrological processes and take into account their characteristic temporal and spatial scales of occurrence. The paper presents a climate change impact assessment performed for the Elbe River basin in Germany (about 100 000 km2). The method used for the study combines: (a) a statistical downscaling method driven by GCM-predicted temperature trend for producing climate scenarios, and (b) a simulation technique based on an ecohydrological semi-distributed river basin model, which was thoroughly validated in advance. The overall result of the climate impact study for the basin is that the mean water discharge and the mean groundwater recharge in the Elbe basin will be most likely decreased under the expected climate change and diffuse source pollution will be diminished. Our study confirms that the uncertainty in hydrological and water quality responses to changing climate is generally higher than the uncertainty in climate input. The method is transferable to other basins in the temperate zone.

scholarly journals Fine dust emissions from active sands at coastal Oceano Dunes, California

2019 ◽  
Vol 19 (5) ◽  
pp. 2947-2964 ◽  
Author(s):  
Yue Huang ◽  
Jasper F. Kok ◽  
Raleigh L. Martin ◽  
Nitzan Swet ◽  
Itzhak Katra ◽  
...  
Keyword(s):  
Climate Models ◽  
Hydrological Cycle ◽  
Large Fraction ◽  
Sand Dunes ◽  
Dust Emission ◽  
Sandy Soils ◽  
Field Measurements ◽  
Dust Storms ◽  
Dust Emissions ◽  
Mineral Coatings

Abstract. Sand dunes and other active sands generally have a low content of fine grains and, therefore, are not considered to be major dust sources in current climate models. However, recent remote sensing studies have indicated that a surprisingly large fraction of dust storms are generated from regions covered by sand dunes, leading these studies to propose that sand dunes might be globally relevant sources of dust. To help understand dust emissions from sand dunes and other active sands, we present in situ field measurements of dust emission under natural saltation from a coastal sand sheet at Oceano Dunes in California. We find that saltation drives dust emissions from this setting that are on the low end of the range in emissions produced by non-sandy soils for similar wind speed. Laboratory analyses of sand samples suggest that these emissions are produced by aeolian abrasion of feldspars and removal of clay-mineral coatings on sand grain surfaces. We further find that this emitted dust is substantially finer than dust emitted from non-sandy soils, which could enhance its downwind impacts on human health, the hydrological cycle, and climate.

scholarly journals Spatial Variation and Controlling Factors of H and O Isotopes in Lancang River Water, Southwest China

2019 ◽  
Vol 16 (24) ◽  
pp. 4932 ◽  
Author(s):  
Kunhua Yang ◽  
Guilin Han ◽  
Jie Zeng ◽  
Bin Liang ◽  
Rui Qu ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
River Water ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Water Security ◽  
Controlling Factors ◽  
Main Stream ◽  
Wet Season ◽  
Lancang River ◽  
O Isotopes

Climate changes and other human activities have substantially altered the hydrological cycle with respect to elevation. In this study, longitudinal patterns in the stable isotopic composition (δ2H and δ18O) of Lancang River water, originating from the Qinghai–Tibetan Plateau, are presented, and several controlling factors in the wet season are hypothesized. Lancang River water δ2H (−145.2‰ to −60.7‰) and δ18O (−18.51‰ to −8.49‰) were low but close to those of the Global Meteoric Water Line. In the upper reaches of the river, δ2H decreased longitudinally, potentially due to groundwater inputs and melting ground ice in the headwater zone and to an increasing proportion of glacier meltwater with decreasing elevation. In the middle reaches of the river, δ2H values increased slowly moving downstream, likely due to shifts in precipitation inputs, as evidenced by the isotopic composition of tributaries to the main stream. In the lower reaches of the river, the isotopic composition was relatively invariant, potentially related to the presence of large artificial reservoirs that increase the water resident time. The results reveal different hydrological patterns along an alpine river in central Asia associated with both natural and anthropogenic processes. Understanding the degree and type of human interference with the water cycle in this region could improve water management and water security.

scholarly journals Hydrological Cycle Algorithm for Continuous Optimization Problems

2017 ◽  
Vol 2017 ◽  
pp. 1-25 ◽  
Author(s):  
Ahmad Wedyan ◽  
Jacqueline Whalley ◽  
Ajit Narayanan
Keyword(s):  
Optimization Problems ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Continuous Optimization ◽  
Global Solutions ◽  
Solution Quality ◽  
Local Optima ◽  
Water Based ◽  
Water Drops ◽  
Continuous Optimization Problems

A new nature-inspired optimization algorithm called the Hydrological Cycle Algorithm (HCA) is proposed based on the continuous movement of water in nature. In the HCA, a collection of water drops passes through various hydrological water cycle stages, such as flow, evaporation, condensation, and precipitation. Each stage plays an important role in generating solutions and avoiding premature convergence. The HCA shares information by direct and indirect communication among the water drops, which improves solution quality. Similarities and differences between HCA and other water-based algorithms are identified, and the implications of these differences on overall performance are discussed. A new topological representation for problems with a continuous domain is proposed. In proof-of-concept experiments, the HCA is applied on a variety of benchmarked continuous numerical functions. The results were found to be competitive in comparison to a number of other algorithms and validate the effectiveness of HCA. Also demonstrated is the ability of HCA to escape from local optima solutions and converge to global solutions. Thus, HCA provides an alternative approach to tackling various types of multimodal continuous optimization problems as well as an overall framework for water-based particle algorithms in general.

Impacts of Snow Darkening by Light-absorbing aerosols on the Water Cycle over the Western Eurasia and East Asia

2020 ◽  
Author(s):  
Jeong Sang ◽  
Maeng-Ki Kim ◽  
William K. M. Lau ◽  
Kyu-Myong Kim
Keyword(s):  
Land Surface ◽  
Moisture Transport ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Initial Conditions ◽  
East Asian ◽  
Development Program ◽  
Eurasian Continent ◽  
Absorbing Aerosols ◽  
Western Eurasia

<p><span>In this paper, we have investigated the snow darkening effects by light-absorbing aerosols on the regional changes of the water cycle over the Eurasian continent using the NASA GEOS-5 Model with aerosol tracers and a state-of-the-art snow darkening module, the Goddard SnoW Impurity Module (GOSWIM) for the land surface. Two sets of ten-member ensemble experiments for 10-years were carried out forced by prescribed sea surface temperature (2002-2011) with different atmospheric initial conditions, with and without SDE, respectively. Results show that SDE can exert a significant regional influence in partitioning the contributions of evaporative and advective processes on the hydrological cycle, during spring and summer season. Over western Eurasia, SDE-induced rainfall increase during early spring can be largely explained by the increased evaporation from snowmelt. Rainfall, however, decreases in early summer due to the reduced evaporation as well as moisture divergence and atmospheric subsidence associated with the development of an anomalous mid- to upper tropospheric anticyclonic circulation. On the other hand, in the East Asian monsoon region, moisture advection from adjacent ocean is a main contributor to rainfall increase in the melting season. Warmer land-surface caused by earlier snowmelt and subsequent drying further increases moisture transport and convergence significantly enhancing rainfall over the region. This findings suggest that the SDE may play an important role in leading to hotter and drier summer over western Eurasia, through coupled land-atmosphere interaction, while enhancing East Asian summer monsoonal precipitation via enhanced land-ocean thermal contrast and moisture transport due to SDE-induced warmer Eurasian continent.</span></p><p> </p><p>This work was supported by the Korea Meteorological Administration Research and Development Program under grant KMI2018-03410.</p>

Carbon pools in a montane old-growth Norway spruce ecosystem in Bohemian Forest: Effects of stand age and elevation

2015 ◽  
Vol 346 ◽  
pp. 106-113 ◽  
Author(s):  
Meelis Seedre ◽  
Jiří Kopáček ◽  
Pavel Janda ◽  
Radek Bače ◽  
Miroslav Svoboda
Keyword(s):  
Norway Spruce ◽  
Stand Age ◽  
Carbon Pools ◽  
Old Growth ◽  
Bohemian Forest

Is regulated even-aged management the right strategy for the Canadian boreal forest?

2004 ◽  
Vol 80 (4) ◽  
pp. 458-462 ◽  
Author(s):  
Yves Bergeron
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Biological Diversity ◽  
Fire Regime ◽  
Age Distribution ◽  
Fire Frequency ◽  
Stand Age ◽  
Old Growth ◽  
Old Growth Forests ◽  
Canadian Boreal Forest

Over the past decade, there has been an increasing interest in the development of forest management approaches that are based on an understanding of historical natural disturbance dynamics. The rationale for such an approach is that management to favour landscape compositions and stand structures similar to those of natural ecosystems should also maintain biological diversity and essential ecological functions. In fire-dominated landscapes, this approach is possible only if current and future fire frequencies are sufficiently low, in comparison to pre-industrial fire frequency, that we can substitute fire with forest management. I address this question by comparing current and future fire frequency to historical reconstruction of fire frequency from studies in the Canadian boreal forest. Current and simulated future fire frequencies using 2× and 3×CO2 scenarios are lower than the historical fire frequency for most sites, suggesting that forest management could potentially be used to recreate the forest age structure of fire-controlled pre-industrial landscapes. Current even-aged management, however, tends to reduce forest variability: for example, fully regulated, even-aged management will tend to truncate the natural forest stand age distribution and eliminate overmature and old-growth forests from the landscape. The development of silvicultural techniques that maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain this variability. Key words: boreal forest, even aged management, fire regime, old-growth forests, climate change, partial cutting

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