نتایج جستجو برای: land productivity

تعداد نتایج: 198818  

2017
A. V. Chari Elaine M. Liu Shing-Yi Wang Yongxiang Wang Rachel Heath Melanie Khamis Adriana Kugler Annemie Maertens Laura Schechter

This paper examines the impact of a property rights reform in rural China that allowed farmers to lease out their land. We find the reform led to increases in land rental activity in rural households. Consistent with a model of transaction costs in land markets, our results indicate that the formalization of leasing rights resulted in a redistribution of land toward more productive farmers. Con...

امیرنژاد, حمید, رفیعی, حامد,

Land and its size are important as the most basic factors of production in agriculture .Fragmentation is one of the main problems that rice producers of Mazandaran province are confronted with. Non-efficiency in farm management, inability in effective using of agriculture technology and machinery, and low range productivity of production are all related to land fragmentation. In order to overco...

1999
Klaus Hubacek Laixiang Sun Günther Fischer

Interim Reports on work of the International Institute for Applied Systems Analysis receive only limited review. Views or opinions expressed herein do not necessarily represent those of the Institute, its National Member Organizations, or other organizations supporting the work. Contents 1 Introduction 1 2 The basic model and its assumptions 3 2.1 Scenario-analysis within a structural economics...

Journal: :Global change biology 2016
Marc Estiarte Sara Vicca Josep Peñuelas Michael Bahn Claus Beier Bridget A Emmett Philip A Fay Paul J Hanson Roland Hasibeder Jaime Kigel Gyorgy Kröel-Dulay Klaus Steenberg Larsen Eszter Lellei-Kovács Jean-Marc Limousin Romà Ogaya Jean-Marc Ourcival Sabine Reinsch Osvaldo E Sala Inger Kappel Schmidt Marcelo Sternberg Katja Tielbörger Albert Tietema Ivan A Janssens

Well-defined productivity-precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity-precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); th...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Laia Alegret Ellen Thomas Kyger C Lohmann

An asteroid impact at the end of the Cretaceous caused mass extinction, but extinction mechanisms are not well-understood. The collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity (Strangelove Ocean) or export productivity (Living Ocean), which caused mass extinction higher in the marine food chain. Phytoplank...

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