Changes in Weed Species Composition in Irrigated Agriculture in Saharan Algeria Amar Eddoud, Elise Buisson, L
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Changes in weed species composition in irrigated agriculture in Saharan Algeria Amar Eddoud, Elise Buisson, L. Achour, K. Guediri, S Bissati, H Abdelkrim To cite this version: Amar Eddoud, Elise Buisson, L. Achour, K. Guediri, S Bissati, et al.. Changes in weed species composition in irrigated agriculture in Saharan Algeria. Weed Research, Wiley, 2018, 58 (6), pp.424- 436. 10.1111/wre.12328. hal-01929114 HAL Id: hal-01929114 https://hal.archives-ouvertes.fr/hal-01929114 Submitted on 21 Nov 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 Changes in weed species composition in irrigated agriculture in Saharan Algeria 2 3 A EDDOUD*, E BUISSON† L ACHOUR‡, K GUEDIRI‡, S BISSATI‡ & H ABDELKRIM 4 χ 5 6 * Université Kasdi Merbah Ouargla, Laboratoire de Bio-Ressources Sahariennes : 7 Préservation et Valorisation, Faculté des Sciences de la nature et de la vie et des sciences de 8 la terre et de l’univers, Ouargla 30 000 Algeria, † Institut Méditerranéen de Biodiversité et 9 d’Ecologie (IMBE), Université d’Avignon et des Pays de Vaucluse, UMR CNRS IRD Aix 10 Marseille Université, IUT Agroparc, BP 61207, 84911 Avignon cedex 09, France, ‡ 11 Université Kasdi Merbah Ouargla, Département des sciences agronomiques Faculté des 12 Sciences de la nature et de la vie et des sciences de la terre et de l’univers, Ouargla 30 000 13 Algeria and χ Ecole Nationale Supérieure d’Agronomie, Département Botanique El- 14 Harrach, Alger 16200 Algeria 15 16 17 18 Running head: Changes in weed composition in Saharan Algeria 19 20 21 22 Correspondance: Dr Elise Buisson, Institut Méditerranéen de Biodiversité et d’Ecologie 23 (IMBE), Université d’Avignon et des Pays de Vaucluse, UMR CNRS IRD Aix Marseille 24 Université, IUT site Agroparc, BP 61207, 84911 Avignon cedex 09, France. Tel: (+33) 25 490843858; Fax: (+33) 490843807; E-mail: [email protected], 26 [email protected] 27 28 29 Summary 30 31 This work characterizes the changes in composition of the weed flora commonly associated 32 with certain southeastern Algerian crops over a twenty-year period. Vegetation sampling was 33 carried out between 1990 and 2010 in three one-hectare date palm plantations that do not 34 have understory crops, six 400-m² greenhouses used for market gardening, and three 30-ha 35 cereal center-pivot irrigation plots. In total, 162 species belonging to 40 families were 36 recorded. As in many other agroecosystems around the world, the dominant families are 37 Poaceae, Asteraceae, Brassicaceae and Amaranthaceae representing 45.1% of the species 38 identified. The weed communities were characterized by a set of species from various 39 origins: species with biregional, triregional, and multiregional origins, Saharo-Arabian and 40 Mediterranean species were particularly well represented. Overall, the most common weed 41 species were: Chenopodium murale, Lolium multiflorum, Melilotus indicus, Lysimachia 42 arvensis, Sonchus oleraceus, Setaria verticillata, Polypogon monspeliensis and Erigeron 43 canadensis, all of which are therophytes. The weed flora differed among the three sampled 44 agroecosystems, which is to be expected, as their respective management sequences are quite 45 different. Weed monitoring over the 20 years showed that weed composition changed 46 overtime, particularly in the palm plantations and the cereal plots. For a better understanding 47 of the drivers of weed composition and changes over time and better weed management, 48 studying weed provenance (crop seed purchase, and organic fertilization) as well as 49 agricultural practices is necessary. 50 51 Keywords: agroecosystems, camel rangeland, cereal center-pivot irrigation plots, date palm 52 plantations, greenhouses, market gardening 53 54 55 Introduction 56 Global changes influence weed distribution, species dominance, and other aspects of weed 57 communities in agroecosystems (e.g. climate change: Zicka and Dukes, 2011). Changes in 58 agricultural practices associated with intensified crop production are by far the leading root 59 cause of weed dynamics: this follows directly from the ecological implications of increased 60 seeding and planting, increased fertilizer and pesticide use, and simplified crop rotation 61 (Kleijn et al., 2009). On the one hand, the difficulty in controlling weeds is one of the major 62 reasons for which farmers are forced to relinquish cultivated plots and to plow new ones; on 63 the other hand, some weed control practices have proven detrimental to many of the plant and 64 animal communities that are associated with agricultural environments (Flohre et al., 2011) 65 while weeds can play an important role in supporting diversity for higher trophic levels 66 (Marshall et al., 2003). Whereas these changes occur on weed communities, a thorough 67 knowledge of the composition of weeds, along with their spatial and temporal distribution, is 68 a prerequisite for good weed management in agroecosystems. 69 In Algeria, several studies have increased our understanding of the composition and 70 distribution of weed flora in various northern regions of the country, with a Mediterranean 71 climate, such as: on the Mediterranean central coast (Chevassut et al., 1988; Boulfekhar, 72 1989; Fenni, 1991; Abdelkrim, 1995), and on the Mediterranean north-eastern Algeria 73 (Fenni, 1991) and north-western Algeria (Kazi Tani et al., 2012) coast. However, many 74 agricultural regions of the country remain under-characterized. 75 Indeed, there currently exist no studies on the weed flora of the Saharan Algeria. 76 Algeria has a flora comprising about 3139 species, of which 653 species (accounting for 77 12.6% of the total number of species) are endemic and distributed among nearly 150 families. 78 Among the endemic flora, more than 25% of the species are associated with crops (Quézel & 79 Santa, 1962-1963). Botanical and plant ecology studies in the Sahara regions are scarce and 80 mainly oriented towards the native flora of natural areas, such as that of camel rangelands 81 (Ozenda, 2004; Chehma et al., 2008) and conservation and narrow endemic species (Brito et 82 al., 2013; Migliore et al., 2013). 83 Our present work aims to show whether the composition of the weed flora associated 84 with irrigated crops in southeastern Saharan Algeria has changed over a period of twenty 85 years from 1990 to 2010. We studied a set of cereal fields, greenhouses and palm plantations. 86 We hypothesized that the weed flora of cereal fields and palm plantations would change little 87 over the study period because cereal cultivation practices are unchanged since the 1980’s and 88 interventions are relatively minor in palm plantations after their establishment. We expected 89 more changes in greenhouses where practices potentially evolve more rapidly. 90 91 Materials and Methods 92 Study area 93 The study was conducted in Hassi Benabdellah, located in northeastern part of Saharan 94 Algeria, about 800 km from Algiers (32°01’N; 5°28’E; Fig. 1). The northern Sahara, which 95 covers an area of 1 million km², receives precipitation in the winter and yields 100±50 mm 96 of rainfall per year (Hamdi-Aissa et al., 2004). It is essentially a transition zone between the 97 northern African Mediterranean steppes and the central Sahara desert, and it was selected 98 mainly for its agricultural potential. Indeed, many important crops, such as dates, greenhouse 99 gardens, and cereals grown using center-pivot irrigation (sometimes called central pivot 100 irrigation or circle irrigation), are all farmed in this region. A relatively recent import to the 101 area, intensive crop cultivation, first appeared in the region in the late 1960s and early 1970s, 102 mainly occupying what had once been open camel rangeland. Although irrigation is applied 103 all year long in the date palm plantations (surface irrigation; once a week from November to 104 March and 2 to 3 times a week the rest of the year), it is only applied during the growing 105 season on cereal plots (center pivot irrigation; 866 mm/m²) and market gardening 106 greenhouses (surface irrigation; twice a week from November to February and 3 times a week 107 from March to May). None of the plots selected for this study were treated with herbicides. 108 109 Sampling method 110 The present study covers the twenty-year period beginning in 1990, and handles the full 111 twenty years in two stages. The first stage relies on a synthesis of all the data from previous 112 studies mentioning exhaustive weed flora sampling in the ITCMI (Institut Technique des 113 Cultures Maraichères et Industrielles) and ITDAS (Institut Technique de Développement de 114 l’Agriculture Saharienne) research stations between 1990 and 2002. For that period, one 115 presence-absence plant list was compiled per year surveyed per crop type (Table 1; ITCMI & 116 ITDAS, 2002). The second stage of the analysis, covering the period from October 2003 to 117 June 2010, is based on weed surveys conducted by the authors according to the following 118 protocol. For both stages, to match the seasonal planting and harvest schedule, surveys were 119 carried out starting in October of each year (x), and repeated in February and June of the 120 following year (x + 1), to give a total of three surveys per year. The data from each set of 121 three surveys were then taken together to fully characterize each October x to June x+1 crop 122 year.