نتایج جستجو برای: astara forest ecosystem

تعداد نتایج: 179070  

Journal: :Environment international 2003
David F Karnosky

Atmospheric CO(2) is rising rapidly, and options for slowing the CO(2) rise are politically charged as they largely require reductions in industrial CO(2) emissions for most developed countries. As forests cover some 43% of the Earth's surface, account for some 70% of terrestrial net primary production (NPP), and are being bartered for carbon mitigation, it is critically important that we conti...

2004
John M. Blair D. A. Crossley Leslie C. Callaham

Blair, J.M., Crossley, D.A., Jr. and Callaham, L.C., 1991. A litterbasket technique for measurement of nutrient dynamics in forest floors. Agric. Ecosystems Environ., 34: 465-471. We describe a litterbasket technique for quantifying litter decomposition and changes in litter and forest floor nutrient pools over time. Litterbaskets are constructed of wire hardware cloth, 10x10x10 cm. Intact core...

Journal: :International journal of biometeorology 2012
Liang Liang Mark D Schwartz Songlin Fei

Phenology shows sensitive responses to seasonal changes in atmospheric conditions. Forest understory phenology, in particular, is a crucial component of the forest ecosystem that interacts with meteorological factors, and ecosystem functions such as carbon exchange and nutrient cycling. Quantifying understory phenology is challenging due to the multiplicity of species and heterogeneous spatial ...

Journal: :Annals of the New York Academy of Sciences 2012
Edward A Johnson Kiyoko Miyanishi

Because of its generally low density of humans and few settlements, the circumpolar boreal forest is often viewed as an untouched wilderness. However, archeological evidence indicates that humans have inhabited the region since the continental glaciers disappeared 8,000-12,000 years ago. This paper discusses the ecological impacts that humans have had on the boreal forest ecosystem through thei...

2016
Irena F. Creed Marian Weber Francesco Accatino David P. Kreutzweiser James M. Vose

Water and forests are inextricably linked. Pressures on forests from population growth and climate change are increasing risks to forests and their aquatic ecosystem services (AES). There is a need to incorporate AES in forest management but there is considerable uncertainty about how to do so. Approaches that manage forest ecosystem services such as fiber, water and carbon sequestration indepe...

2001
Christopher S. Potter

Ecosystem models are useful tools for evaluating environmental controls on carbon and water cycles under past or future conditions. In this paper we compare annual carbon and water fluxes from nine boreal spruce forest ecosystem models in a series of sensitivity simulations. For each comparison, a single climate driver or forest site parameter was altered in a separate sensitivity run. Driver a...

2015
Harald Vacik Jordi Garcia-Gonzalo Eric J. Jokela

The Special Issue “Providing Ecosystem Services under Climate Change: Community of Practice of Forest Decision Support Systems” is based on the presentations given at the 24th World Congress of the International Union of Forest Research Organizations and provides an overview on Forest Management Decision Support Systems currently designed and applied for the sustained provision of ecosystem ser...

2002
Martine Antona Pierre Bommel François Bousquet Christophe Le Page

Since the end of the 70’s, various forest policies have been implemented in the Sahel to address the problem of ecosystem degradation and the increasing need for fuelwood energy. In Niger, a new environment-oriented policy is now being implemented, in conjunction with the decentralization process and the transfer of specific forest user-rights to the local population. Incentives, regulations an...

Journal: :Environmental pollution 2010
Steven G McNulty Johnny L Boggs

Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it is believed to potentiall...

2015
Y. Zhang M. Voigt H. Liu

During the past several decades, observational data have shown a faster increase in hot temperature extremes than the change in mean temperature. Increasingly high extreme temperatures are expected to affect terrestrial ecosystem function. The ecological impact of hot extremes on vegetation production, however, remains uncertain across biomes in natural climatic conditions. In this study, we in...

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