Assessing Agrobiodiversity in Home Garden Ecosystems of some Regions in Khorasan Razavi Province

 Characteristics such as the high levels of agrobiodiversity, the efficiency of the nutrition, and also variety in ecological and socio-economic functions have altered home gardens into the appropriate model for achieving a sustainable agricultural system. So far, fewer studies in relation to these features have been done in home gardens of dry and semi-arid regions. Protection of diversity with a particular emphasis on agricultural biodiversity is fundamental to sustainable development in food production and hence food security. Expansion of industrial agriculture in the form of monoculture for the purpose of maximizing the yield with the aid of high-yielding varieties and intensive use of inputs has hampered the ecological functions of food production systems worldwide. This problem can be overcome by the application of a wide array of ecological agriculture practices, of which food production in home gardens is only one of them. This environmentally sound practice is an old system of land use almost in all parts of the world with a wide range of dimensions. A combination of different plants, from herbs to trees and in cases with poultry and other low-weight animals, provides a complex sustainable system of food production. This type of subsistence food production is based on local knowledge and normally is part of the residential area or, to the, low input. Food produced in this system is consumed locally, and women are the main element in both production and marketing. Exchanges of experience and knowledge, seed, and also tools, and labors are very common in neighboring communities. The purpose of the present study was to investigate the agrobiodiversity of home gardens in an arid environment of Khorasan Razavi Province.Materials and

Data collection for this study was based on the fieldwork with the distribution of questioners. For this purpose, 17 villages from 3 highly populated counties of Mashhad/ Quchan and Nyshabour were selected, and 164 questioners were distributed with a face-to-face procedure. After the collection and validation of data, only 136 questionnaires were selected, data were extracted, and finally, an analysis was carried out. Afterward, the Shannon biodiversity index, Simpson index, and species richness were calculated. The amount of carbon sequestered was also calculated by an equation referred to in the literature. For the calculation of biodiversity indices, the area under cultivation of each species was used. Based on the available previous studies, seven basic functions for home gardens were assigned.

Results showed the highest Shannon index of species diversity equal to 1.88 for the county of Neishabour; however, the highest functional diversity was found in Quchan. More the 79 percent of changes in the Shannon index are caused by changes in species richness. Stepwise regression analysis revealed that changes in species richness, home area, and household population were the factors that caused 84 percent of changes in functional diversity. Home gardens in these three counties sequester 8.1 tons of carbon dioxide per hectare, and this amount showed a decreasing trend where the distance from the vehicle roads was increased.

It was revealed that with taking distance from the main roads, the amount of carbon dioxide (kg per m2) decreased by tree species.AcknowledgmentsThe authors acknowledge the financial support of this project (grant number 2/19719) by the Vice President for Research and Technology, Ferdowsi University of Mashhad, Iran.