نتایج جستجو برای: mean annual temperature c

تعداد نتایج: 2001499  

2015
Sam W. Wood Lynda D. Prior Helen C. Stephens David M. J. S. Bowman Paul Adam

Tracking the response of forest ecosystems to climate change demands large (≥1 ha) monitoring plots that are repeatedly measured over long time frames and arranged across macro-ecological gradients. Continental scale networks of permanent forest plots have identified links between climate and carbon fluxes by monitoring trends in tree growth, mortality and recruitment. The relationship between ...

2011
S. Gubler J. Fiddes M. Keller

Measurements of environmental variables are often used to validate and calibrate physically-based models. Depending on their application, the models are used at different scales, ranging from few meters to tens of kilometers. Environmental variables can vary strongly within the grid cells of these models. Validating a model with a single measurement is therefore delicate and susceptible to indu...

Journal: :محیط شناسی 0
فرامرز خوش اخلاق استادیار جغرافیای طبیعی، دانشکدۀ جغرافیا، دانشگاه تهران محمد امین مرادی مقدم دانشجوی کارشناسی ارشد اقلیم شناسی، دانشکدۀ جغرافیا، دانشگاه تهران محمدامین حیدری دانشجوی دکتری اقلیم شناسی، دانشکدۀ جغرافیا، دانشگاه تهران شیرین صفایی دانشجوی کارشناسی ارشد اقلیم شناسی، دانشکدۀ جغرافیا، دانشگاه تهران

today, climate change is one of the most important scientific and even the political – social issues. the causes of climate change can be divided into natural and human - made. natural factors have the long-term performance and long history, such as the cycle of solar activity, dusts and gases of volcanic eruptions, geodetic and static agents and etc. human-made factors was mainly formed and ac...

2006
Thomas L. Powell Rosvel Bracho Jiahong Li Sabina Dore C. Ross Hinkle Bert G. Drake

Biological and physical controls regulating variation of seasonal and interannual ecosystem carbon exchange in a scrub oak ecosystem in central Florida were determined by measuring net ecosystem exchange of CO2 (NEE) between the atmosphere and vegetation using the eddy covariance technique continuously for 6 years (April 2000–March 2006). Total net ecosystem production (NEP) was nearly 20 t C m...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2014
Robbie Hart Jan Salick Sailesh Ranjitkar Jianchu Xu

Responses by flowering plants to climate change are complex and only beginning to be understood. Through analyses of 10,295 herbarium specimens of Himalayan Rhododendron collected by plant hunters and botanists since 1884, we were able to separate these responses into significant components. We found a lack of directional change in mean flowering time over the past 45 y of rapid warming. Howeve...

Journal: :international journal of environmental research 0
kh. ashrafi graduate faculty of environment, university of tehran, p.o.box 14155-6135, tehran, iran m. shafiepour graduate faculty of environment, university of tehran, p.o.box 14155-6135, tehran, iran l. ghasemi graduate faculty of environment, university of tehran, p.o.box 14155-6135, tehran, iran b. araabi faculty of electrical and computer engineering, university of tehran, tehran, iran

the objective of this paper is to develop an artificial neural network (ann) model which can beused to predict temperature rise due to climate change in regional scale. in the present work data recorded overyears 1985-2008 have been used at training and testing steps for ann model. the multilayer perceptron(mlp) network architecture is used for this purpose. three applied optimization methods a...

Journal: :The Journal of animal ecology 2013
Priyanga Amarasekare Renato M Coutinho

1. Lately, there has been interest in using the intrinsic growth rate (rm) to predict the effects of climate warming on ectotherm population viability. However, because rm is calculated using the Euler-Lotka equation, its reliability in predicting population persistence depends on whether ectotherm populations can achieve a stable age/stage distribution in thermally variable environments. Here,...

Journal: :Annals of agricultural and environmental medicine : AAEM 2013
Attila Trájer János Bobvos Anna Páldy Katalin Krisztalovics

The increase of Lyme borreliosis (LB) can be expected due to climate change, while the distribution of the disease and annual activity of the vector and host animals depend on several factors of the environment. The presented study aimed to assess expressly the spring season temperature dependence on the incidence of LB in Hungary. The weekly LB data were obtained from the National Epidemiologi...

2014
Michael Kessler Johanna M. Toivonen Steven P. Sylvester Jürgen Kluge Dietrich Hertel

We studied tree height in stands of high-Andean Polylepis forests in two cordilleras near Cuzco (Peru) with respect to variations in human impact and climatic conditions, and compared air and soil temperatures between qualitatively defined dry and humid slopes. We studied 46 forest plots of 100 m(2) of five Polylepis species at 3560-4680 m. We measured diameter at breast height (dbh) and tree h...

2013
Attila Trájer János Bobvos Anna Páldy Katalin Krisztalovics

The increase of Lyme borreliosis (LB) can be expected due to climate change, while the distribution of the disease and annual activity of the vector and host animals depend on several factors of the environment. The presented study aimed to assess expressly the spring season temperature dependence on the incidence of LB in Hungary. The weekly LB data were obtained from the National Epidemiologi...

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