چکیده:
Sustainable range management needs the accurate estimation yield and determining of grazing capacity in rangelands. It is easy to obtain yield estimation with indirect methods.
For this purpose, the relation between cover and forage yield of range species were
studied in steppic rangelands of Yazd. Measurements of cover and forage yield were
carried out with plot area and clipping and weighting methods, respectively. Every year,
one hundred and twenty quadrate plots were systematically assessed from 2000 until
2004 in mid-May. In addition to mentioned measurement, four sampling was done until
early November in 2004. Data were analyzed in regression and correlation programs
(SPSS 10.0).
Results showed that there was significant relation (p<0.01) between cover and forage yield of studied species during 4 years (2001-2004), but 3 species out of 7 studied species had significant relation in 2000-drought year (p<0.05). Obtained relations and also fitted models were varied in different years and stages. Therefore, the yield estimation is possible by using cover, but in dry years. These characteristics are applied for annual yield estimation of steppic range species by double sampling model with cover
خلاصه ماشینی:
"Relationship between cover and yield of some range species in steppic region of Yazd province Abstract Sustainable range management needs the accurate estimation yield and determining of grazing capacity in rangelands.
For this purpose, the relation between cover and forage yield of range species were studied in steppic rangelands of Yazd.
These characteristics are applied for annual yield estimation of steppic range species by double sampling model with cover .
Payne (1974) studied relationship between cover and yield of 48 plant species observed in 160 quadrats, in various vegetation communities of Beaverhead National Forest located in south western of Montana.
In the present study, relationship between canopy cover and yield of some important range species in Yazd,s rangeland were investigated.
Correlation coefficient between yield and cover percentage, coefficient of determination, significant levels and calculated equation for each species during 2000-2004 have been presented in table 2 and in 5 stages during year 2004 in table 3.
Arzani (1989) reported that calculated equations for each kind of vegetation that are suitable for yield estimation belong to specific condition and time of data collection .
According to the results in the present study except in severe drought and different times and location robust correlation generally exist between cover and yield of studied species.
Shape and canopy cover are generally changed by severe grazing (Holechek et al 1995, Moghaddam 1998, Vallentine 1990), but result of this study and review of other works (Arzani 1989, Begdeli 1997, Sadeghi Nia et al 2001) were based on data collected from exclousers."