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Testing the ecological communities of different areas for convergence, in the sense of remarkable similarity in the characteristics of the species present, has a long history in biology. Recently, numerical methods have been developed for comparing community-level convergence to an explicit null model. No valid method has been known for testing the significance of texture convergence when the species are weighted by their abundance. Six combinations of method variants are tested on random datasets. A valid P value (i. e., with P . 0. 05 in no more than 5% of the cases) is obtained so long as for each species the distribution of abundances across sites is retained, and only the assignment of character values is randomised. Further restriction is not necessary for obtaining a valid P value, and can lead to a test with considerably lower power to detect convergence. The power of the test with free matching of character values to species is only moderate with 10 sites, though improved with larger numbers of sites. Previous methods for detecting texture convergence have examined convergence only in the mean value for any character. It is possible that the external environment might be reflected in the community mean of a character, leaving the imprint of convergence on the shape of the distribution, rather than the mean. A method for comparing the shape is described, and it is shown that the null model is valid also for this test statistic.  

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We investigated the neighbourhood-scale effect of weeding on native plants in Lance McCaskill Nature Reserve, Canterbury, New Zealand. The reserve is an unproductive basin of limestone debris. Originally set up to protect the Castle Hill buttercup, Ranunculus crithmifolius var. paucifolius , the reserve also offers protection for nationally endangered species: Myosotis colensoi and Lepidium sisymbrioides . Our aim was to investigate whether removal of introduced plants increased the cover of remaining native species. We removed introduced plants, by hand, every year for 6 years from half of the plots. We used nonparametric multivariate analysis to compare overall species cover.The results suggest that weeding does benefit the native plants in this area. There was a significant difference in the mean of the overall native species cover between the weeded and the non-weeded plots. For the ten species measured, the mean area covered per square metre was higher in the weeded plots than in the non-weeded plots in most years of the study. There was considerable variation in the data and we discuss possible reasons for this.

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Over recent years a number of attempts have been made to assess the carbon mitigation potential of European agricultural land. Here we review the progress made by comparing pre- and post-Kyoto estimates of C mitigation potential, and review recent advances, such as the inclusion of trace gases in C mitigation calculations. We then briefly discuss ways in which our regional estimates of agricultural carbon mitigation potential might be improved. Finally, we set the findings for Europe in the context of the global terrestrial carbon cycle, and the historical global loss of carbon from soils due to agriculture.

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Cereal breeding programs are interested in increasing the number of generations per year to reduce the time needed to develop new cultivars. A common method to accomplish this is to extend the photoperiod to speed up plant growth. For oat, this method is problematic because the species responds to changes in light and temperature. Current methods of fast generation cycling in oat require embryo rescue, which is labor intensive and has a low success rate. Recently a method was developed using increased photoperiod and foliar mineral supplement to reduce generation time for wheat and barley. We evaluated this newly published method in oat and found that anthesis occurred 15 ± 3 days faster, however there was a 3-fold reduction in seed count and a 2-fold reduction in inflorescence weight. In addition, we measured endogenous ascorbate to evaluate the physiological status of the plants under fast generation cycling conditions. For oat, fast generation cycling would be effective to more rapidly advance populations using single seed descent, but not as useful when seed yield is important.

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Cereal Research Communications
Authors:
B.L. Béres
,
N.Z. Lupwayi
,
F.J. Larney
,
B. Ellert
,
E.G. Smith
,
T.K. Turkington
,
D. Pageau
,
K. Semagn
, and
Z. Wang

Research indicates that not all crops respond similarly to cropping diversity and the response of triticale (× Triticosecale ssp.) has not been documented. We investigated the effects of rotational diversity on cereals in cropping sequences with canola (Brassica napus L.), field pea (Pisum sativum L.), or an intercrop (triticale:field pea). Six crop rotations were established consisting of two, 2-yr low diversity rotations (LDR) (continuous triticale (T-T_LDR) and triticale-wheat (Triticum aestivum L.) (T-W_LDR)); three, 2-yr moderate diversity rotations (MDR) (triticale-field pea (T-P_MDR), triticale-canola (T-C_MDR), and a triticale: field pea intercrop (T- in P_MDR)); and one, 3-yr high diversity rotation (HDR) (canola-triticale-field pea (C-T-P_HDR)). The study was established in Lethbridge, Alberta (irrigated and rainfed); Swift Current (rainfed) and Canora (rainfed), Saskatchewan, Canada; and carried out from 2008 to 2014. Triticale grain yield for the 3-yr HDR was superior over the LDR rotations and the MDR triticale-field pea system; however, results were similar for triticale-canola, and removal of canola from the system caused a yield drag in triticale. Triticale biomass was superior for the 3-yr HDR. Moreover, along with improved triticale grain yield, the 3-yr HDR provided greater yield stability across environments. High rotational diversity (C-T-P_HDR) resulted in the highest soil microbial community and soil carbon concentration, whereas continuous triticale provided the lowest. Net economic returns were also superior for C-T-P_HDR ($670 ha–1) and the lowest for T-W_LDR ($458 ha–1). Overall, triticale responded positively to increased rotational diversity and displayed greater stability with the inclusion of field pea, leading to improved profitability and sustainability of the system.

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