Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2010.642.648Bromus kopetdaghensis and Two Nurse Shrubs, Astragalus meschedensis and Acantholimon raddeanam in a Semiarid Rangeland]]>JankjuM. MaghamniaA. 1220101313Plant-plant interactions are known as the main biotic drivers of the vegetation dynamics. Therefore, understanding such processes is beneficial for the applied vegetation management. The aim of this research was to investigate the type and intensity of plant-plant interaction during the time course of a growth season. We studied ecophysiological aspects of facilitation and competition between two aridland shrubs, A. meschedensis Bunge and A. raddeanam Czernjak and one perennial grass, B. kopetdaghensis Krasch. Soil and plant sampling were carried out for shrubs and the grass that were either growing alone or the grass was growing under the canopy of shrubs. In Spring (May), soil humidity weight was higher under the shrubs+grass than the grass-only site. By the beginning of Summer (July) grass consumed the common soil water and rapidly terminated its yearly growth. Therefore, in August and September, soil humidity weight was lower under the shrubs+grass than shrub-only sites. Photosynthesis rate of B. kopetdaghensis was sharply reduced from the beginning towards the end of growth season, but was not varied between the different plant combinations. Leaf proline measurement in July indicated higher stress for B. kopetdaghensis that were growing under shrubs than those of open areas. In conclusion, we found facilitation effects of shrubs on the grass at the early times of growth season, but it shifted into the competition for water during summer times. The outcome of plant interaction was positive for the grass but negative for the shrubs, especially A. meschedensis.]]>Armas, C. and F.I. Pugnaire,2005937889Acuna-Rodriguez, I.S., L.A. Cavieres and E. Jianoli,200679329336Bates, L.S., R.P. Waldren and I.D. Teare,197339205207Callaway, R.M.,199561306349Belsky, A.J., R.G. Amundson, J.M. Duxbury, S.J. Riha, A.R. Ali and S.M. Mwonga,19892610051024Cavieres, L.A., M.T.K. Arroyo, M. Molina-Montenegro, C. Torres and A. Penaloza,200213547554Castro, J., R. Zamora, J.A. Hodar, J.M. Gomez and L. Gomez-Aparicio,200412352358Cavieres, L.A., E.I. Badano, A. Sierra-Almeida and M.A. Molina-Montenegro,200739229236Choler, P., R. Michalet and R.M. Callaway,20018232953308Dormann, C.F. and R.W. Brooker,200223227301Eckstein, R.L.,2005166525536Garcia, M., F. Montane, J. Pique and J. Retana,2007242391397Hacker, S.D. and M.D. Bertness,19998020642073Sharifabad, H.H. and M. Dorri,2003Vol. 2,Holmegren, M.,2000906778Holzapfel, C., K. Tielborger, H.A. Pavag, J. Nigel and H. Sternbeug,20067268279Jankju, M.,200822123133Jankju, M.,2009Artemisia aucheri Boiss and Bromus tectorum L: Case study, steppic rangeland of Nasr-Abad, Yazd, Iran.]]>52105115Jankju, M. and H. Griffiths,2006148555563Jankju, M., A. Delavari and A. Gangeali,2008Bromus kopetdaghensis in shrublands.]]>2314327Joffer, R., J. Vacher, C. Lianos and G. Long,198967196Kikvidze, Z., L. Khetsuriani, D. Kikodze and R.M. Callaway,2006177782Kitzberger, T., D.F. Steinaker and T.T. Veblen,20008119141924Ko, L.J. and P.B. Rich,19931303142Liancourt, P., R.M. Callaway and R. Michalet,20058616111618Ludwig, P. and J.C. Menaut,199517093105Maestre, F.T., S. Bautista, J. Cortina and J. Bellot,20011116411655Maestre, F.T., S. Bautista and J. Cortina,20038431863197Maestre, F.T., R.M. Callaway, F. Valladares and C.J. Lortie,200997199205McAllister, C.A., A. Knapp and L.A. Maragni,19981174046Melgoza, G., R.S. Nowark and R.J. Tausch,1990Bromus tectorum (cheatgrass) and two native species.]]>83713Michalet, R., R.W. Brooker, L.A. Cavieres, Z. Kikvidze and C.J. Lortie et al.,20069767773Moeini, A.H., R. Heidari, A. Hassani and A.A. Dizaji,2006Ocimum basilicum).]]>6763767Mooney, H.A.,19723315346Mordelet, P. and J.C. Menaut,19956223228Novoplansky, A. and D.E. Goldberg,200112199208Nagel, J.M. and K.L. Griffin,2004Lythrum salicaria.]]>6101111Pugnaire, F.I. and M.T. Luque,2001934249Schultz, C.M., C.A. Gehring and T.G. Whithman,2007173135145Shumway, S.W.,2000124138148SPSS,1997Strain, B.R.,1969in situ.]]>50511513Sunchez-Veasquez, L.R., S. Quintero-Gradilla, F. Aragon-Cruz and M.R. Pineda-Lopez,2004Brosimum alicastrum reintroduction in secondary tropical forest.]]>198401404Wang, Y.S., C.J. Chu, F.T. Maestre and G. Wang,200833108113Tatar, O. and M.N. Gevrek,20087409412