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H.M. Steyn, N. van Rooyen, M.W. van Rooyen and G.K. Theron

-Verlag New York 1974 353 364 Clark S.C. Some effects of temperature and photoperiod on growth and floral development in three winter annuals. New Phytol. 1969 68 1137 44 Cross H.Z. Zuber M.S. Prediction of flowering dates in maize based on different methods of estimating thermal units. Agron. J. 1972 64

Shmuel Galili, Ran Hovav, Aharon Bellalou, Orit Amir-Segev, Hana Badani, Tova Deutch, Lior Rubinovich, Aviv Asher, Tomer Faraj and Alon Singer

software ( ISI 1999 ) and after running outlier passes to remove observations with T > 2.5 ( ISI 1999 ). The quality of prediction by the equations was expressed by the coefficient of determination (R 2 cal, encompassing linearity and precision) which defines the proportion of variability in the reference

Ronen Kadmon and Avi Shmida

Theoretical studies suggest that fluctuations in availability of resources should lead to related fluctuations in the intensity of competition, and that significant competition should occur only in years of severe resource scarcity. This prediction has been supported by a number of studies conducted in animal populations, but has never been tested in plant populations. In this study, we performed neighbor removal experiments in conjunction with rainfall manipulation experiments, to test how fluctuations in rainfall, the major limiting resource for desert annuals, affect the intensity of competition in populations of the desert annual Stipa capensis. In order to test for the effect of spatial heterogeneity on the relationships between rainfall and competition intensity, populations were studied in three types of habitats: slopes, depressions, and wadis. Competition intensity was quantified, for each combination of habitat and rainfall, as the percentage of potential seed yield per germinating plant which was prevented due to competitive effects. Intensities of competition in the studied populations varied considerably between habitats, between seasons, and between rainfall manipulation treatments. In the most favorable habitat, the wadi, competition was always intense, independent of rainfall conditions. In the drier, slope and depressions habitats, natural and experimental changes in the amount of the yearly rainfall had considerable effects on competition intensity, but most pronounced competition was associated with high resource availability, a pattern which is opposite to the pattern that was predicted and documented for animal populations. The overall results suggest that competitive effects may have critical influence on the population dynamics of the species studied. This contradicts previous hypotheses on the relative importance of competition in desert plant populations.

Henri N. Le Houérou

According to the Global Circulation Models presently available, the atmospheric temperature in the Mediterranean Basin would increase by 3°C ± 1.5 by 2030–2050, as a result of the rise in the amount of CO2 and other warming gases in the atmosphere. At present, it is, however, impossible to make any dependable prediction as to the evolution of rainfall during the next 60 years; the best “guestimate” would indicate little, if any, change in the amount and/or distribution of rainfall, but perhaps a somewhat increased variability. The paper discusses the consequences of a temperature rise in terms of its impact on vegetation, ecosystems, crops and land use evolution and distribution patterns. On a global regional scale, however, the change will be influenced far more by the exponential human demographic growth (presently 2.8% yr−1) than by the possible temperature increase. Depending on growth scenarios, the total population of the 14 countries considered, situated between the Caspian Sea and the Atlantic Ocean, will reach between 800 and 2000 million by 2050. The impact of such an anthropozoic pressure on vegetation, ecosystems, and land use would obviously be tremendous, judging from past and present trends and from the limited areas where the pressure is now comparable. Deforestation, desertization, and erosion will result in changes of major geological magnitude in this part of the world. These would, in turn, have inevitable sociopolitical consequences on these countries as well as on adjacent areas, particularly in the northern part of the Mediterranean Basin. The premises of the change are already being felt in some European countries.

Shmuel Galili, Hovav Ran, Evgenia Dor, Joseph Hershenhorn, Arye Harel, Orit Amir-Segev, Aharon Bellalou, Hana Badani, Evgeny Smirnov and Guy Achdari

accuracy of its predictions. Accordingly, disease severity was significantly lower and yield significantly higher in protected vs. untreated plots. In the early '90s, Fusarium wilt was identified for the first time in several fields in Israel. All of the cultivars except cv. Ayalla were found to be

Ahmet Pişkin

. , Emmerich A. , Baumgarten G. , Winner C. , Beiss U. ( 1974 ). Prediction of molasses sugar from beet analysis . Zucker 27 : 2 – 15 . Tugnoli V. , Bettini G. ( 2002 ). Organic sugar beet growing techniques: first experiments in Italy . Proceedings of

Shiran Ben-Zeev, Jajaw Bimro, Vered Barak and Yehoshua Saranga

. , Verheye W. ( 1993 ). Crop growth requirements and approach to yield prediction for barley and tef in the central highlands of Ethiopia . Pedologie XLIII-3 , 357 – 372 . van Delden S.H. , Vos J. , Ennos A.R. , Stomph T.J. ( 2010 ). Analysing lodging of

Tao Deng, Richard J. Abbott, Wenqing Li, Hang Sun and Sergei Volis

.J. , Peterson A.T. , Nyari A.S. , Perkins S.L. , Guralnick R.P. 2007 . Locating pleistocene refugia: Comparing phylogeographic and ecological niche model predictions . PLoS One. 2 : e563. Wang P.X. , Sun X.J. 1994 . Last glacial maximum in China

Elisabeth A. Wheeler and Pieter Baas

Edited by Lisa Boucher

.), Analytical paleobiology. Short courses in paleontology , No. 4 : 207 – 214 ( 1996 ). Paleontological Society , University of Tennessee , Knoxville . Rossell JA , Olson ME , Anfodillo T . 2017 . Scaling of xylem vessel diameter with plant size: causes, predictions, and outstanding questions . Curr

Misha Vorobyev and Robert Brandt

Basic concepts of color vision in animals and, in particular in the honeybee, are reviewed. Four models of color discrimination in honeybees are presented. Because visual systems in Hymenoptera are similar to that of the honeybee, such models can also be used to describe color discrimination in many hymenopteran pollinators. We compare predictive capacities of the models and give practical recommendations for their usage. Although models have different mathematical formulations, in most cases they give similar predictions. Examples where predictions of different models deviate are discussed.