Perpendicular distance sampling (PDS) is a fast probability-proportional-to-size method for inventory of downed wood. However, previous development of PDS had limited the method to estimating only one variable (such as volume per hectare, or surface area per hectare) at a time. Here, we develop a general design-unbiased estimator for PDS. We then show how that estimator can be used to develop s...

Combine harvesters have a very important task in grain crop harvesting. Combine harvesters must fulfil lot of technological requirements regarding the field conditions, crop type, as well as the quality performance and optimal costs. The problem is that it is the main harvesting technology of cereals in the world and it has seasonal character of work, which has to be done in a relatively short ...

in order to select and release of nassim, a new cultivar of red clover, the researcher carried out the researches at the field of seed and plant improvement institute (spii) in karaj and some research stations such as shahrekord, sanandej, kermanshah, arak, gorgan during years 1996-2006. the experimental research was carried out design rcbd with six treatments and four replications during years...

In this paper we develop methods to investigate the efficiency of alternative contracts for Carbon (C) sequestration in cropland soils, taking into account the spatial heterogeneity of agricultural production systems and the costs of implementing more efficient contracts. We describe contracts being proposed for implementation in the United States and other countries that would pay farmers for ...

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BACKGROUND TEK, ecological and economic aspects of columnar cacti were studied in the Tehuacán Valley, Mexico to design sustainable regimes of fruit harvest. We analysed the amounts of edible fruit, seeds and flowers produced per hectare of cardonal, jiotillal and tetechera forests, their economic value and actual extraction rates, hypothesizing that the economic benefits of these NTFP would po...