Review of household ranch models

Household ranch is a basic management unit and complicated production system critical for restoration of grassland ecosystem, conservation of biodiversity and improvement in incomes of farmers and herdsmen. While environment, natural resources, economy, society and management have been included in household ranch, the direction of future studies now includes the quantification, precision, stereotype and marketization of household ranch. Modeling has been important in the production, management and research in household ranch and in minimizing the factors restricting the management and development of household ranch and op-timizing ranch benefits. Several various models and softwares have been developed in the past 20 years in relation to household ranch developement, and used in the simulation of grass growth, animal production, greenhouse gas emission and system manage-ment as well as in operating household ranch system and making management and policy decisions. The main characteristics of household ranch were summarized in this paper based on review of 24 models and comparison of four factors - household ranch production, management, herb growth and greenhouse gas emission. 1) There was a rapid development of models in the area of ani-mal husbandry. 2) Farm models were more comprehensive than household ranch models, especially for dairy and beef farms. 3) The balances in forage, energy and benefit maximization were the basis of the simulations. 4) The model required a range of parameters, most of which were difficult to obtain. 5) There was lack of universal model with a wide scope of application. Based on production condition of household ranches in China, ACIAR, GrassGro and SEPATOU models were fit for household ranches in natural grassland areas and IFSM model was good for intensive farm or enterprise systems. Depending on the current state of grassland and livestock production systems in China, it was necessary to base proven results of research and practice, and interdisciplinary and trans-regional co-operations for household ranch model building and application in China.