scholarly journals HETEROFOR 1.0: a spatially explicit model for exploring the response of structurally complex forests to uncertain future conditions. II. Phenology and water cycle

2019 ◽  
Author(s):  
Louis de Wergifosse ◽  
Frédéric André ◽  
Nicolas Beudez ◽  
François de Coligny ◽  
Hugues Goosse ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Tree Growth ◽  
Leaf Development ◽  
Forest Growth ◽  
Spatially Explicit ◽  
Model Assessment ◽  
Pearson's R ◽  
The Impact ◽  
Pearson’S R

Abstract. Climate change affects forest growth in numerous and sometimes opposite ways and the resulting trend is often difficult to predict for a given site. Integrating and structuring the knowledge gained from the monitoring and experimental studies into process-based models is an interesting approach to predict the response of forest ecosystems to climate change. While the first generation of such models operates at stand level, we need now individual-based and spatially-explicit approaches in order to account for structurally complex stands whose importance is increasingly recognized in the changing environment context. Among the climate-sensitive drivers of forest growth, phenology and water availability are often cited as crucial elements. They influence, for example, the length of the vegetation period during which photosynthesis takes place and the stomata opening, which determines the photosynthesis rate. In this paper, we describe the phenology and water balance modules integrated in the tree growth model HETEROFOR and evaluate them on six Belgian sites. More precisely, we assess the ability of the model to reproduce key phenological processes (budburst, leaf development, yellowing and fall) as well as water fluxes. Three variants are used to predict budburst (Uniforc, Unichill and Sequential), which differ regarding the inclusion of chilling and/or forcing periods and the calculation of the coldness or heat accumulation. Among the three, the Sequential approach is the least biased (overestimation of 2.46 days) while Uniforc (chilling not considered) best accounts for the interannual variability (Pearson’s R = 0.68). For the leaf development, yellowing and fall, predictions and observation are in accordance. Regarding the water balance module, the predicted throughfall is also in close agreement with the measurements (Pearson’s R = 0.856, bias = −1.3 %) and the soil water dynamics across the year is well-reproduced for all the study sites (Pearson’s R comprised between 0.893 and 0.950, and bias between −1.81 and −9.33 %). The positive results from the model assessment will allow us to use it reliably in projection studies to evaluate the impact of climate change on tree growth and test how diverse forestry practices can adapt forests to these changes.

scholarly journals HETEROFOR 1.0: a spatially explicit model for exploring the response of structurally complex forests to uncertain future conditions – Part 2: Phenology and water cycle

2020 ◽  
Vol 13 (3) ◽  
pp. 1459-1498 ◽  
Author(s):  
Louis de Wergifosse ◽  
Frédéric André ◽  
Nicolas Beudez ◽  
François de Coligny ◽  
Hugues Goosse ◽  
...  
Keyword(s):  
Climate Change ◽  
Leaf Development ◽  
European Beech ◽  
Local Environment ◽  
Phase Model ◽  
Spatially Explicit ◽  
Two Phase ◽  
Sessile Oak ◽  
Pearson's R ◽  
Pearson’S R

Abstract. Climate change affects forest growth in numerous and sometimes opposite ways, and the resulting trend is often difficult to predict for a given site. Integrating and structuring the knowledge gained from the monitoring and experimental studies into process-based models is an interesting approach to predict the response of forest ecosystems to climate change. While the first generation of models operates at stand level, one now needs spatially explicit individual-based approaches in order to account for individual variability, local environment modification and tree adaptive behaviour in mixed and uneven-aged forests that are supposed to be more resilient under stressful conditions. The local environment of a tree is strongly influenced by the neighbouring trees, which modify the resource level through positive and negative interactions with the target tree. Among other things, drought stress and vegetation period length vary with tree size and crown position within the canopy. In this paper, we describe the phenology and water balance modules integrated in the tree growth model HETEROFOR (HETEROgenous FORest) and evaluate them on six heterogeneous sessile oak and European beech stands with different levels of mixing and development stages and installed on various soil types. More precisely, we assess the ability of the model to reproduce key phenological processes (budburst, leaf development, yellowing and fall) as well as water fluxes. Two two-phase models differing regarding their response function to temperature during the chilling period (optimum and sigmoid functions) and a simplified one-phase model are used to predict budburst date. The two-phase model with the optimum function is the least biased (overestimation of 2.46 d), while the one-phase model best accounts for the interannual variability (Pearson's r=0.68). For the leaf development, yellowing and fall, predictions and observations are in accordance. Regarding the water balance module, the predicted throughfall is also in close agreement with the measurements (Pearson's r=0.856; bias =-1.3 %), and the soil water dynamics across the year are well reproduced for all the study sites (Pearson's r was between 0.893 and 0.950, and bias was between −1.81 and −9.33 %). The model also reproduced well the individual transpiration for sessile oak and European beech, with similar performances at the tree and stand scale (Pearson's r of 0.84–0.85 for sessile oak and 0.88–0.89 for European beech). The good results of the model assessment will allow us to use it reliably in projection studies to evaluate the impact of climate change on tree growth in structurally complex stands and test various management strategies to improve forest resilience.

scholarly journals Variation in Water Supply Leads to Different Responses of Tree Growth to Warming

2021 ◽  
Author(s):  
Pengfei Zheng ◽  
Dandan Wang ◽  
Xinxiao Yu ◽  
Guodong Jia ◽  
Ziqiang Liu ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Supply ◽  
Climate Warming ◽  
Tree Growth ◽  
Structural Equation Models ◽  
Growing Season ◽  
Forest Growth ◽  
Arid Ecosystems ◽  
Carbon Sinks ◽  
The Impact

Abstract Background: Global climate change, which includes changes in precipitation, prolonged growing seasons, and drought stress caused by overall climate warming, is putting increased pressure on forest ecosystems globally. Understanding the impact of climate change on drought-prone forests is a key objective in assessing forest responses to climate change.Results: In this study, we assessed tree growth trends and changes in physiological activity under climate change based on patterns in tree rings and stable isotopes. Additionally, structural equation models were used to analyze the climate drivers influencing tree growth, with several key results. (1) The climate in the study area showed a trend of warming and drying, with the growth of tree section areas decreasing first and then increasing, while the water use efficiency showed a steady increase. (2) The effects of climate warming on tree growth in the study area have transitioned from negative to positive. The gradual advance of the growing season and the supply of snowmelt water in the early critical period of the growing season are the key factors underlying the reversal of the sensitivity of trees to climate. (3) Variation in water supply has led to different responses of tree growth to warming, and the growth response of Pinus tabuliformis to temperature rise was closely related to increased water availability.Conclusions: Our study indicates that warming is not the cause of forest decline, and instead, drought caused by warming is the main factor causing this change. If adequate water is available during critical periods of the growing season, boreal forests may be better able to withstand rising temperatures and even exhibit increased growth during periods of rising temperatures, forming stronger carbon sinks. However, in semi-arid regions, where water supply is limited, continued warming could lead to reduced forest growth and even death, which would dramatically reduce carbon sinks in arid ecosystems.

scholarly journals Simulation of future climate scenarios and the impact on the water availability in southern Brazil

2021 ◽  
Vol 43 ◽  
pp. e56026
Author(s):  
Gabriela Leite Neves ◽  
Jorim Sousa das Virgens Filho ◽  
Maysa de Lima Leite ◽  
Frederico Fabio Mauad
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Water Availability ◽  
Meteorological Data ◽  
Future Climate ◽  
Climate Scenarios ◽  
Southern Brazil ◽  
Climate Data ◽  
Intergovernmental Panel ◽  
The Impact

Water is an essential natural resource that is being impacted by climate change. Thus, knowledge of future water availability conditions around the globe becomes necessary. Based on that, this study aimed to simulate future climate scenarios and evaluate the impact on water balance in southern Brazil. Daily data of rainfall and air temperature (maximum and minimum) were used. The meteorological data were collected in 28 locations over 30 years (1980-2009). For the data simulation, we used the climate data stochastic generator PGECLIMA_R. It was considered two scenarios of the fifth report of the Intergovernmental Panel on Climate Change (IPCC) and a scenario with the historical data trend. The water balance estimates were performed for the current data and the simulated data, through the methodology of Thornthwaite and Mather (1955). The moisture indexes were spatialized by the kriging method. These indexes were chosen as the parameters to represent the water conditions in different situations. The region assessed presented a high variability in water availability among locations; however, it did not present high water deficiency values, even with climate change. Overall, it was observed a reduction of moisture index in most sites and in all scenarios assessed, especially in the northern region when compared to the other regions. The second scenario of the IPCC (the worst situation) promoting higher reductions and dry conditions for the 2099 year. The impacts of climate change on water availability, identified in this study, can affect the general society, therefore, they must be considered in the planning and management of water resources, especially in the regional context

The impact of drought on tree growth in Mediterranean sites

2021 ◽  
Author(s):  
Giovanna Battipaglia ◽  
Francesco Niccoli ◽  
Arturo Pacheco-Solana
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Sustainable Forest Management ◽  
Climatic Factors ◽  
Management Strategies ◽  
Ring Width ◽  
Limiting Factor ◽  
Individual Tree ◽  
Annual Growth Rings ◽  
The Impact

<p>Climate-induced forest mortality is a critical issue in the Mediterranean basin, with major consequences for the functioning of these key ecosystems. Indeed, in Mediterranean ecosystems, where water stress is already the most limiting factor for tree performance, climatic changes are expected to entail an increase in water deficit. In this context, annual growth rings can provide short- (e.g., years) and long-term (e.g., decades) information on how trees respond to drought events. With climate change, <em>Pinus pinaster</em> and <em>Pinus pinea</em> L. are expected to reduce their distribution range in the region, being displaced at low altitudes by more drought tolerant taxa such as sub Mediterranean <em>Quercus</em> spp.</p><p>This study aims was to assess the physiological response of <em>Pinus</em> and <em>Quercus</em> species growing in the Vesuvio National park, located in Southern Italy and where an increase of temperature and drought events has been recorded in the recent years. Our preliminary results underlined the importance of temperature on the tree ring width of all the analyses species. The high temperatures can cause a change in the constant kinetics of the RuBisCo, leading to a consequent decrease in carboxylation rate and thus to a reduction in tree growth. On the other hand, also precipitation seemed to affect the growth of the sampled trees: indeed, in all the chronologies a reduction in growth was found after particular dry years: for example, the low rainfall in 1999 (455 mm/year) determined a drastic decline in growth in 2000 in all the species. In addition to the climatic factors, competition can also play an important role in the growth rate: dendrochronological analyzes have highlighted how stand specific properties (i.e. density, structure and composition) can influence individual tree responses to drought events. The knowledge of those researches should be integrated into sustainable forest management strategies to minimize the potential impacts of climate change on forest ecosystems.</p>

Effect of climate change, drought, and insects on oak-pine forests in the Ozark highlands

2020 ◽  
Author(s):  
◽  
Shengwu Duan
Keyword(s):  
Climate Change ◽  
Forest Growth ◽  
Pine Forests ◽  
Spatial And Temporal Variation ◽  
Oak Forests ◽  
Drought Effect ◽  
Ozark Highlands ◽  
Disturbance Regimes ◽  
Warming Climate ◽  
The Impact

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI--COLUMBIA AT REQUEST OF AUTHOR.] Oak-dominated forests in the Ozarks Highlands of Arkansas and Missouri have been suffering severe oak decline and this became a chronic problem since the late 1970s. Such decline became increasingly severe as numerous dense oak forests in this region approaching physiological maturity. Repeated droughts and insect outbreaks in the Ozarks Highlands from 1998 to 2015 accelerate the decline process and resulted in increased mortality of the oaks, particularly those in red oak group. Given these concerns, the overall objective of this dissertation was to conduct a regional scale assessment to evaluate and predict the impact of drought and insects on the oak forests under changing climate. This dissertation contained three main objectives: 1) to evaluate the drought effect on forest growth phenology and productivity by using spatially-explicit drought indices and land surface phenology techniques to capture oak, pine and mixed oak-pine forests' responses to repeated droughts; 2) to develop a climate sensitive biotic disturbance agent (BDA) module in forest landscape modeling framework to quantify the relative importance in determining the insect disturbance regimes under the warming climate; and 3) to predict the effects of insect disturbance, climate change and their interactions on forest composition under alternative climate and insect disturbance scenarios. The dissertation provided a methodology to disassemble the spatial and temporal variation of drought conditions in the Ozark Highlands and provided new insights into improving drought resistance and recovery capacity of forests with different species under climate change. The results from this dissertation also helped to understand the importance of vegetation feedback in predicting inset disturbance regimes under a warming climate as they may mediate or even reverse the expectation of increased insect disturbance in this region. In addition, the projections of how tree species will response to insect disturbance will benefit decision making in silvicultural prescriptions and longterm management plans in the Ozark Highlands.

scholarly journals The Impact of Land Use/Land Cover Change (LULCC) on Water Resources in a Tropical Catchment in Tanzania under Different Climate Change Scenarios

2019 ◽  
Vol 11 (24) ◽  
pp. 7083 ◽  
Author(s):  
Kristian Näschen ◽  
Bernd Diekkrüger ◽  
Mariele Evers ◽  
Britta Höllermann ◽  
Stefanie Steinbach ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Land Cover ◽  
Water Balance ◽  
Land Cover Change ◽  
Sub Saharan Africa ◽  
Climate Change Scenarios ◽  
Land Use Land Cover ◽  
The Impact

Many parts of sub-Saharan Africa (SSA) are prone to land use and land cover change (LULCC). In many cases, natural systems are converted into agricultural land to feed the growing population. However, despite climate change being a major focus nowadays, the impacts of these conversions on water resources, which are essential for agricultural production, is still often neglected, jeopardizing the sustainability of the socio-ecological system. This study investigates historic land use/land cover (LULC) patterns as well as potential future LULCC and its effect on water quantities in a complex tropical catchment in Tanzania. It then compares the results using two climate change scenarios. The Land Change Modeler (LCM) is used to analyze and to project LULC patterns until 2030 and the Soil and Water Assessment Tool (SWAT) is utilized to simulate the water balance under various LULC conditions. Results show decreasing low flows by 6–8% for the LULC scenarios, whereas high flows increase by up to 84% for the combined LULC and climate change scenarios. The effect of climate change is stronger compared to the effect of LULCC, but also contains higher uncertainties. The effects of LULCC are more distinct, although crop specific effects show diverging effects on water balance components. This study develops a methodology for quantifying the impact of land use and climate change and therefore contributes to the sustainable management of the investigated catchment, as it shows the impact of environmental change on hydrological extremes (low flow and floods) and determines hot spots, which are critical for environmental development.

Drought and water management in the German agricultural sector - a participatory system dynamics approach

2020 ◽  
Author(s):  
Rodrigo Valencia ◽  
Sabine Egerer ◽  
María Máñez
Keyword(s):  
Climate Change ◽  
Water Management ◽  
Water Balance ◽  
System Dynamics ◽  
Model Building ◽  
Elevated Temperatures ◽  
Agricultural System ◽  
Group Model ◽  
Wide Range ◽  
The Impact

<p>Higher temperatures and changes in precipitation patterns caused by climate change may potentially affect water availability for agriculture and increase the risk of crop loss in Northeast Lower Saxony (NELS), Germany. The drought of 2018 showed that an intensification of irrigation might be a temporary solution. However, a long-term increase in water extraction, especially during drought periods, is not a sustainable solution. To assess possible water management solutions, we implement a participatory system dynamics approach, namely Group Model Building, to develop a qualitative system dynamics model (QSDM) describing the agricultural system and its relation to water resources in NELS.</p><p>The development of the QSDM seeks to understand the complexity of the interactions between agriculture and hydrological systems, recognize the stakeholders’ needs and identify risks and weaknesses of both systems. By understanding this, we expect to reinforce the adaptation process, reduce conflict and be able to suggest tailored solutions and adaptation measures. The QSDM incorporates a wide range of perceptions, as twenty stakeholders ranging from farmers, government agencies, environmental protection organizations and local water authorities were involved in the QSDM development. Their perceptions were recorded in the QSDM through individual interviews and a group workshop.</p><p>Through the QSDM, we identified and mapped the structure and connections between agriculture and the water balance. It was also possible to identify the strongest feedback loops governing both sectors as well as their influence on the current situation. The loops represent behaviors and structures, which might become unmanageable under climate change conditions. The causal loops include the different uses for the available water of the region, the impact of irrigation, the significance of crop selection and the importance of sustainable soil management.</p><p>By analyzing the system this way, we confirmed that climate change poses a risk to the region as elevated temperatures could increase the crop water demand and increase the need for irrigation. In the same way, changes in the rain patterns could affect the water balance of the region. The agricultural system has, however, potential to adapt by implementing new water management strategies such as restructuring water rights, water storage and reuse and conjunctive water use. Other measures include increasing the irrigation efficiency, changing crops and enhancing the soil quality, among others.</p>

ANALYTICAL REVIEW OF INVESTIGATIONS OF THE CLIMATE CHANGE IMPACT ON RIVER WATER FLOW

2019 ◽  
pp. 64-73
Author(s):  
Hanna Bolbot ◽  
Vasyl Grebin
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Water Flow ◽  
Hydrological Modeling ◽  
Complex Method ◽  
Water Runoff ◽  
Impact Of Climate Change ◽  
Insufficient Attention ◽  
The World ◽  
The Impact

A huge number of scientific researches in the world are devoted to the research of global and regional climate change and their impact on water resources. In Ukraine, this issue is receiving insufficient attention. Researches have been done to assess current trends in river runoff, but future estimates of changes in Ukraine’s water flow have been presented in only a few papers. Present studies of this issue are conducted using hydrological modeling. The ensemble approach is widely used to increase the reliability of estimates of possible future changes in water runoff, that is, the use of data from several GCM and RCM models, with subsequent averaging of their results. Unfortunately, this methodological approach was not used in Ukraine. Using the water-balance method, local manifestations of global climate change within individual catchments can be estimated with sufficient quality. To estimate the temporal variability of the components of the water balance, a comparison of the available hydrological and climatic characteristics of the current period with the period of the climatic norm is used, as well as the method of differential integral curves, which reflects characteristic tendencies in the long-term dynamics of individual components of the water balance. Analyzing all available approaches to research on the impact of climate change on water flow, we can conclude that a complex method is the best for this investigation. Given that a large number of methods are used in the world, reliable estimates can be obtained by developing unified and validated methods and techniques. Therefore, the first step in this way should be a comparative analysis of the results obtained by the most commonly used methods. In the field of water, climate change can lead to changes in rainfall, hydrodynamic regime and water balance of rivers, increase of catastrophic floods and excessive drought, shortage of fresh water. Unfortunately, there is insufficient attention paid to the study of this issue in Ukraine. That is why assessing the impact of climate change on water flow and forecasting them is a very necessary task.

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