Indikatoren zur Schätzung des Trockenheitsrisikos in Buchen- und Fichtenwäldern

Indicators for quantitative assessment of drought risks in beech and Norway spruce forests The application of climate models to forecast future forest development asks for quantitative drought-response relationships, with the term “drought” first needing a definition. The long-term data series of an intercantonal forest observation program allowed to test various drought indicators, to compare them and to derive quantitative relationships for beech and Norway spruce. For basal area increment of both tree species indicators of the site water balance (SWB) performed best. For beech mortality site water balance and several indicators basing on the ratio between actual and potential evapo-transpiration (ETa/ETp) were equivalent, whereas for spruce mortality ETa/ETp during the first 80 days of the season was the best indicator. With these indicators the average drought related growth reduction after 2003 – a year with extreme drought – was estimated to amount to 32% for beech and 37% for Norway spruce. Mortality of Norway spruce increased by 130%, whereas the estimates for the increase of beech mortality vary between 54 and 110%, depending on the indicator. The observed quantitative relationships for growth were applied to map drought responses of growth for Switzerland. The maps clearly show the dry regions of Switzerland (northern Switzerland, southern Jura foothills, Lemanic region, Valais and Rhine valley around Chur), where basal area increment of beech and Norway spruce was reduced by more than 40%.

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Trockenperioden seit 1900 und Waldwachstum: eine Analyse langfristiger Datenreihen | Drought periods since 1900 and growth of forest stands: an analysis of long-term data series

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2008.0352 ◽

2008 ◽

Vol 159 (10) ◽

pp. 352-361 ◽

Cited By ~ 7

Author(s):

Andreas Zingg ◽

Anton Bürgi

Keyword(s):

Tree Growth ◽

Abies Alba ◽

Basal Area ◽

Basal Area Increment ◽

Growth And Yield ◽

Data Series ◽

Silver Fir ◽

Eine Analyse ◽

Daily Precipitation Data

Drought during the vegetation period has en effect on tree growth. Using daily precipitation data and growth records from long-term research plots, we investigated what can be defined as “drought” and how strong its effect is. Dry or humid periods are defined as the deviation from the long-term daily mean of precipitation. Such periods must last at least 60 days to be considered as being decisive for tree growth. The drought values are used together with other site and stand parameters as explaining variables in a model for the basal area increment for Norway spruce (Picea abies [L] H. Karst.), silver fir (Abies alba Mill.), European beech (Fagus sylvatica L.) and oak (Quercus L), based on data from long-term growth and yield plots which are located in the neighbourhood of precipitation measurement stations. These models explain 55 to 89% of the variance. In drought situations basal area increment drops clearly for spruce and beech, for fir only weakly and oak shows no reaction. Furthermore, we checked if there happened additional or compulsory felling after drought periods and if the basal area growth changed significantly compared to the growth in the period before. For both it is not the case, despite distinct drought periods in the last century, especially in the 40s with the extreme year of 1947. Therefore we do not expect dramatic changes for the investigated species in similar drought situations under the prerequisite that the other conditions do not change essentially.

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Negative impact of ozone on the stem basal area increment of mature Norway spruce in south Sweden

Forest Ecology and Management ◽

10.1016/j.foreco.2006.05.059 ◽

2006 ◽

Vol 232 (1-3) ◽

pp. 146-151 ◽

Cited By ~ 33

Author(s):

Per Erik Karlsson ◽

Göran Örlander ◽

Ola Langvall ◽

Johan Uddling ◽

Urban Hjorth ◽

...

Keyword(s):

Norway Spruce ◽

Negative Impact ◽

Basal Area ◽

Basal Area Increment ◽

South Sweden

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Mitigation of drought stress in forest stands - insights from a throughfall-exclusion and a thinning experiment

10.5194/egusphere-egu2020-10592 ◽

2020 ◽

Author(s):

Timo Gebhardt ◽

Benjamin D. Hesse ◽

Thorsten E.E. Grams ◽

Christian Ammer ◽

Karl-Heinz Häberle

Keyword(s):

Drought Stress ◽

Forest Management ◽

Soil Water ◽

Norway Spruce ◽

Intraspecific Competition ◽

Basal Area ◽

Understorey Vegetation ◽

Management Measures ◽

Throughfall Exclusion

Due to climate change suitable forest management measures are required to mitigate the proposed exacerbating drought events as already observed in central Europe in summer 2003, 2015, 2018, and 2019. This contribution summarizes the findings of two long-term field experiments studying different forest management measures aiming at mitigating drought in forest stands.The first study investigated the potential of mixing tree composition for mitigating drought stress in Norway spruce (Picea abies [L.] Karst.). To this end, a five-year study with repeated summer droughts, experimentally induced via throughfall-exclusion (TE), was performed. The study objects were mature (60-80 years) old stands of Norway spruce in monoculture and mixture with European beech (Fagus sylvatica (L.). The impacts of repeated summer droughts were assessed on about 100 trees distributed on 12 plots and accessible via canopy crane (Kranzberg forest ROOF experiment in southern Germany). Predawn leaf water potentials of Norway spruce reached minima of -1.8 MPa, but were not affected by species mixture. Nevertheless, daily xylem sapflow density was increased up to 40% in mixture compared to pure strands. Likewise, stem growth, i.e. relative basal area increment, showed significantly higher drought resistance in mixture compared to monocultures.While altering forest stand composition seems to be promising on the long-term, the conversion from monocultures is often economically not suitable for young stands in the short- to medium-term. Therefore, reducing intraspecific competition via thinning is a frequently discussed option investigated in the second, eight-year-long study. In a 26-year old Norway spruce monoculture, three thinning intensities, i.e. unchanged (control), moderate thinning (MT with reduced basal area by 43%) and heavy thinning (HT, reduced basal area by 67%) were applied, potentially mitigating drought by reducing intraspecific competition and increasing soil water availability. Indeed, in both thinning intensities the duration of drought stress for the trees (soil water content below critical value) was reduced compared to controls for up to 5-7 years following the event. However, increased radiation and higher growth rates of the individual trees accompanied by the fast establishment of a vital ground vegetation diminished the difference in stand transpiration between MT and HT within two years. Moreover, belowground competition with the understorey vegetation suppressed fine root recovery under HT compared to MT in contradiction to increased leaf area on HT on tree-level and therefore increased transpirational demand.The presented studies suggest admixing of broadleaved beech into monocultures of Norway spruce to be a promising management measure in the long-term. In juvenile monocultures of Norway spruce frequent and intense thinning interventions while preventing the establishment of a vital understorey vegetation appears to be a promising forest measure, mitigating drought without losing sight of economic needs.

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Long-term effects of thinning and fertilization on growth of red fir in northeastern California

Canadian Journal of Forest Research ◽

10.1139/x05-048 ◽

2005 ◽

Vol 35 (6) ◽

pp. 1285-1293 ◽

Cited By ~ 7

Author(s):

Jianwei Zhang ◽

William W Oliver ◽

Robert F Powers

Keyword(s):

Basal Area ◽

Basal Area Increment ◽

Stand Development ◽

Long Term Effects ◽

Annual Increment ◽

Fourth Period ◽

Abies Magnifica ◽

The Impact ◽

Second Period

To determine the impact of fertilization and thinning on growth and development of red fir (Abies magnifica A. Murr.) stands, we established an experiment in a 60-year-old stand using a 2 × 3 factorial design with nitrogen-fertilized and nonfertilized treatments and three stocking levels. Plots were established in 1976 and were measured every 5 years for 26 years. The periodic annual increment in basal area was 97%, 51%, 38%, and 33% greater in fertilized trees than in nonfertilized trees during the first, second, third, and fourth 5-year periods, respectively. After 20 years, annual basal area increment was greater in nonfertilized trees. The response of annual volume increment to fertilization was not statistically significant until the fourth period. Yet, volume increases of the fertilized plots were 25%92% greater than those of the nonfertilized plots from 1976 to 1996. Similarly, basal area increment was greater in lightly thinned plots than in unthinned plots from the second period on, until heavy mortality during 19962002. Basal area increment was greater in the heavily thinned plots from the fourth period on. Results indicate that red fir can respond to fertilization and thinning quickly and that both treatments speed stand development. In addition, fertilization increases the stand's carrying capacity. Therefore, forest managers can use these silvicultural practices to improve stand growth, to reduce fire fuels, and to accelerate stand development.

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Wood density in Norway spruce: changes with thinning intensity and tree age

Canadian Journal of Forest Research ◽

10.1139/x05-118 ◽

2005 ◽

Vol 35 (7) ◽

pp. 1767-1778 ◽

Cited By ~ 48

Author(s):

Tuula Jaakkola ◽

Harri Mäkinen ◽

Pekka Saranpää

Keyword(s):

Norway Spruce ◽

Wood Density ◽

Basal Area ◽

Tree Age ◽

Individual Tree ◽

Thinning Intensity ◽

Individual Tree Growth ◽

Spruce Stands ◽

Individual Trees

The effect of thinning intensity on growth and wood density in Norway spruce (Picea abies (L.) Karst.) was investigated in two long-term thinning experiments in southeastern Finland. The stands were approaching maturity, and their development had already been studied for 30 years. The intensities of thinning were low, normal, and high (i.e., the stand basal area after the thinning was, on average, 40, 27, and 24 m2·ha1, respectively, in Heinola, and 30, 28, and 17 m2·ha1 in Punkaharju, respectively). Compared with the low thinning intensity, the normal and high thinning intensities increased the basal-area increment of individual trees by 52% and 68%, respectively. Normal and high thinning intensities resulted in a relatively small reduction (1%4%) of mean ring density compared with low thinning intensity. The random variation in wood density between and within trees was large. About 27% of the total variation in wood density was related to variation between rings. Our results indicate that the prevailing thinning intensities in Norway spruce stands in Fennoscandia cause no marked changes in wood density. At least, the possible reduction in wood density is low compared with the increase in individual tree growth.

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Silver Fir Defoliation Likelihood Is Related to Negative Growth Trends and High Warming Sensitivity at Their Southernmost Distribution Limit

ISRN Forestry ◽

10.5402/2012/437690 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Juan Carlos Linares ◽

J. Julio Camarero

Keyword(s):

Abies Alba ◽

Basal Area ◽

Basal Area Increment ◽

Silver Fir ◽

Climatic Data ◽

Vegetation Shifts ◽

Temperature And Precipitation ◽

Crown Defoliation ◽

Visual Assessments

Changes in radial growth have been used to estimate tree decline probability since they may indicate tree responses to long- and short-term stressors. We used visual assessments of crown defoliation, an indicator of decline, and retrospective tree-ring analyses to determine whether climate-growth sensitivity and tree growth rates may be used as predictors of tree die-off probability in Abies alba (silver fir) at the Spanish Pyrenees. We used climatic data to calculate standardized temperature and precipitation data and drought indexes. Basal area increment was measured for declining (defoliation > 50%) and nondeclining (defoliation < 50%) silver firs in stands with contrasting defoliation. Logistic regressions were applied to predict tree die-off. Since the early 1980s, a synchronised reduction in basal area increment was observed in declining trees. The basal area increment trend correctly classified 64% of declining trees and 94% of nondeclining trees. The growth sensitivity to water deficit, temperature, and a drought index also significantly predicted silver fir decline, but providing underestimated predictions. Our findings underscore the idea that long-term climatic warming seems to be a major driver of growth decline in silver fir. Ongoing growth reduction and enhanced mortality may promote vegetation shifts in declining Pyrenean A. alba forests.

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A Basal Area Increment Model for Norway Spruce in Mixed Stands in Estonia

Scandinavian Journal of Forest Research ◽

10.1080/02827580050160529 ◽

2000 ◽

Vol 15 (1) ◽

pp. 97-102 ◽

Cited By ~ 11

Author(s):

Kalev Jogiste

Keyword(s):

Norway Spruce ◽

Basal Area ◽

Basal Area Increment ◽

Mixed Stands

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Time series modelling of relationships between climate and long-term radial growth of loblolly pine

Canadian Journal of Forest Research ◽

10.1139/x90-097 ◽

1990 ◽

Vol 20 (6) ◽

pp. 738-742 ◽

Cited By ~ 15

Author(s):

D. N. Jordan ◽

B. G. Lockaby

Keyword(s):

Loblolly Pine ◽

Palmer Drought Severity Index ◽

Basal Area ◽

Severity Index ◽

Basal Area Increment ◽

Drought Severity ◽

Annual Increment ◽

Growth Trend ◽

Index Value

Time series techniques were utilized to evaluate the influence of selected climatic factors on basal area increment growth of loblolly pine (Pinustaeda L.) in rural Alabama and to address the possibility of a changing growth trend. This study is unique in its application of these techniques to an important southern United States timber species. An important asset of the study is the availability of long-term weather records from a weather station only 0.5 km distant. Basal area increment from 1906 to 1986 was modelled using an autoregressive integrated moving average model. Significant predictors of annual increment are previous annual increment, average temperature in June, precipitation in May, June, and August, the annual drought index for southern pine, and the Palmer drought severity index value for August. The best predictor variable examined was the August Palmer drought severity index value. Basal area increment was examined for interventions indicating a changing growth trend. No significant (p ≤ 0.05) interventions were observed in the climatically modelled series.

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Testando diferentes esquemas da Parametrização Cumulus do modelo WRF, para a região norte Nordeste do Brasileiro (Testing different WRF Cumulus parameterization schemes for the north-eastern region of Brazil)

Revista Brasileira de Geografia Física ◽

10.26848/rbgf.v12.3.p754-767 ◽

2019 ◽

Vol 12 (3) ◽

pp. 754

Author(s):

Vanessa de Almeida Dantas ◽

Vicente Paulo Silva Filho ◽

Eliane Barbosa Santos ◽

Adilson Wagner Gandu

Keyword(s):

Climate Models ◽

Cumulus Parameterization ◽

Weather Research And Forecasting ◽

Data Series ◽

Eastern Region ◽

Statistical Tool ◽

Taylor Diagram ◽

Weather And Climate ◽

Weather Research

O maior obstáculo para a realização de estudos de clima no Nordeste do Brasil é a falta de séries contínuas de dados, observações de longo prazo, espacialmente bem distribuídas, e de alta qualidade. Fontes alternativas de dados têm sido buscadas. Umas das principais ferramentas para estudos atmosféricos de longo prazo, são os modelos climáticos globais e regionais. A utilização de um modelo regional permite a obtenção de séries quadri-dimensionais contínuas, relativas a qualquer fenômeno atmosférico. Dos modelos regionais disponíveis na literatura, o Weather Research and Forecasting (WRF) vem se destacando como modelo de última geração de previsão numérica de tempo e clima. Este estudo teve como objetivo, avaliar a sensibilidade do modelo WRF a s diferentes opções físicas de parametrização no sobre a região norte do Nordeste Brasileiro (NNEB). O esquema de convecção que melhor representasse as condições meteorológicas e climáticas para o NNEB seria escolhido. A escolha foi feita comparando-se os resultados das simulações dos dados de chuva do produto MERGE/CPTEC. As análises foram realizadas para dois casos de sistemas convectivos de mesoescala (SCM) sobre o NNEB, que ocorreram nos dias 14 de janeiro e 30 de março de 2016. Nos resultados obtidos, foi possível perceber que as simulações apresentaram grandes diferenças de acordo com o esquema de cumulus utilizado. O Diagrama de Taylor foi utilizado como ferramenta estatística para analisar a destreza das simulações do WRF em relação aos dados observados, gerados pelo produto Merge. A B S T R A C TThe greatest obstacle to conducting climate studies in Northeast Brazil is the lack of continuous data series, long-term, spatially well-distributed, and high-quality observations. Alternative sources of data have been sought. One of the main tools for long-term atmospheric studies is the global and regional climate models. The use of a regional model allows the obtaining of continuous four-dimensional series, related to any atmospheric phenomenon. From the regional models available in the literature, the Weather Research and Forecasting (WRF) have been standing out as a model of last generation of numerical forecast of weather and climate. The objective of this study was to evaluate the sensitivity of the WRF model to the different physical parameterization options on the northern Northeast of Brazil (NNEB). The convection scheme that best represented the weather and climate conditions for the NNEB would be chosen. The choice was made by comparing the results of the simulations with the rain data of the MERGE / CPTEC product. The analyzes were performed for two cases of mesoscale convective systems (SCN) on the NNEB, which occurred on January 14 and March 30, 2016. In the obtained results, it was possible to perceive that the simulations showed great differences according to the cumulus scheme used. The Taylor Diagram was used as a statistical tool to analyze the dexterity of the WRF simulations in relation to the observed data, resulting in the parameterization of Grell (E5) in the event of the day 01/01 and Grelle Freitas (E5) for the day 30 / 03, with BIAS around 1.Keywords: Regional modeling, Precipitation, Climatology.

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