Weed Vegetation of Arable Land in the Czech Republic: Environmental a Management Factors Determining Weed Species Composition

Home , Consolida regalis, Sinapis arvensis

Biologia 69/4: 443—448, 2014 Section Botany DOI: 10.2478/s11756-014-0331-6

Weed vegetation of arable land in the Czech Republic: environmental a management factors determining weed species composition

Michaela Kolářová*, Luděk Tyšer & Josef Soukup

Czech University of Life Sciences, Department of Agroecology and Biometeorology, Faculty of Agrobiology, Food and Natural Resources, Kamýcká 129,CZ-16521 Prague 6 – Suchdol, Czech Republic; e-mail: [email protected]

Abstract: This paper reports on the current situation in weed vegetation composition on arable land in selected areas of the Czech Republic, assessment of influence of selected variables: applied management systems (conventional, organic), crops (winter cereals, root crops) and altitude and ranking of the importance of these particular factors. A phytocoenological survey was conducted from 2006 to 2008 during a vegetation period using relevés that were 100 m2 in size, placed in the central part of fields. In total, 202 relevés of agricultural vegetation were recorded. The combined environmental variables explained 10.6% of the variability. Based on the pCCAs, the highest effect was found at altitude, which explains 5.1% of the species composition variability. The second and third most significant factors are crop and management system, which explain 3.3% and 1.8% of the variability, respectively. The lowlands were generally characterised by the thermophilous summer annual weed species. The higher altitudes were populated by species that are typical for colder areas and poor, humid, and acidic soil types, such as cambisoil. Key words: altitude; management system; weed diversity; root crops; winter cereals

Introduction & Lososová (2009), where on a regional scale, the relative importance of different crop types and their as- Arable weed vegetation is a very dynamical system. It sociated management is higher than the relative im- responds to all human activities (such as crop selec- portance of climatic variables. Also, Fried et al. (2008) tion and crop rotation practices, weed control methods, indicated that the major variations in species composi- fertilization, seed treatment, soil cultivation) that oc- tion between fields were associated with crop type. Šilc curred in the past or currently within the land cultiva- et al. (2009) showed that the most important parameter tion. At the same time weed communities are influenced in South-Eastern Europe was phytogeography and the by conservative elements of the landscape (e.g., alti- second was crop. Pinke et al. (2010) suggest that the tude, topography, climate, geology and soil conditions). most variation in species composition was explained by An important factor is the effect of seasonal changes on the seasonal aspect. Altitude was the least important different temporal aspects of weed vegetation. factor. At the same time, he adds that the relative im- Weed community research in this area has a long portance of climatic variables decreased with decreasing tradition. Thus, resolving such issues as the relations of lengths of their gradients; in their study area the lengths weeds to temperature, water regime, soil pH, soil tex- of the altitude gradient were very low and accordingly ture and type and nutrient content has been of great in- the related climatic effects were not so strong. terest by many scientists (e.g., Ellenberg 1950; Kropáč The aim of this study was to assess the current sit- 1981). Currently, the whole complex of environmental uation of weed vegetation composition on arable land variables can be statistically analysed with the intro- in selected areas of the Czech Republic and to evalu- duction of multivariate statistical methods (Hallgren et ate effects of selected variables: management systems al. 1999). Similar studies often lead to contradictory re- applied, crop and environmental site conditions char- sults. Lososová et al. (2004) showed on the base of huge acterised by altitude, and ranking of the importance of relevé data sets from the Czech Republic and Slovakia these particular factors. Factor of different management that major changes in weed species composition were system is highlighted because the studies analysing that associated with a complex gradient of increasing alti- effect are very rare in our region and threre is a need tude, precipitation, decreasing temperature and acidity to compare the importance of this factor with other of the soil. Different results were obtained by Cimalová variables.

* Corresponding author

c 2014 Institute of Botany, Slovak Academy of Sciences 444 M. Kolářová et al.

Fig. 1. Map of the Czech Republic that shows the relevés taken.

Table 1. Characteristics of natural conditions (Němec 2001).

Altitude < 250 m 250–350 m > 350 m

Average annual air temperature ( ◦C) 9–10 8–9 5–8 Average annual rainfall (mm) 500–600 500–650 550–900 Sum of temperatures above 10 ◦C 2800–3100 2400–2800 2000–2800 Main soil units chernozems, phaeozems, ﬂuvisols chernozems, haplic luvisols cambisols Percentage of arable land (%) > 80 > 80 > 60

Material and methods In total, 202 relevés of agricultural vegetation across the Czech Republic (Fig. 1) were recorded. Of these, 108 and A three-year phytocoenological survey was undertaken from 94 relevés were taken on conventionally farmed fields (53 in 2006 to 2008 in the Czech Republic. The presented data in winter cereals and 55 in root crops) and organic fields (54 in this study were obtained from 27 conventional farms and winter cereals and 40 in root crops), respectively. The fully 35 registered organic farms. Organic management practices developed vegetation was monitored (cereals, mainly June have been used for at least 2 years in all organic farms. and July and root crops, mainly August and September). The winter cereals, i.e., winter wheat (Triticum aestivum), The elevation ranged from 175 to 650 m a.s.l., repre- winter barley (Hordeum vulgare), rye (Secale cereale), spelt senting a fundamental region of arable land in the Czech (Triticum spelta) and triticale (x Triticosecale rimpaui), and Republic. From the viewpoint of altitude, the relevés were root crops, i.e., sugar beet (Beta vulgaris subsp. vulgaris divided into 3 groups: < 250 m a.s.l., 77 relevés; 250-350 m var. altissima), potatoes (Solanum tuberosum), maize (Zea a.s.l., 66 relevés and > 350 m a.s.l., 59 relevés, characteris- mays), oil pumpkin (Cucurbita pepo subsp. pepo), feeding carrots (Daucus carota), fodder beet (Beta vulgaris subsp. ing a complex of environmental conditions that are suitable vulgaris var. rapacea) and beet-root (Beta vulgaris subsp. for growing concrete crops (Table 1) and the occurrence of vulgaris var. vulgaris) fields were selected for weed sam- certain weed species. pling. At each site, one phytocoenological relevé with a stan- The values that were recorded using a Braun-Blanquet dard size of 100 m2 was recorded. The coverage of species scale were transformed to an ordinal scale (van der Maarel was estimated using a nine-degree Braun-Blanquet cover- 1979). Detrended correspondence analysis (DCA) from the abundance scale (Braun-Blanquet 1964). The sampling was CANOCO 4.5 package (ter Braak & Šmilauer 2002) was conducted in the central parts of monitored fields to de- used to assess the overall variation patterns in species com- scribe the real status of weed occurrence because the field position. Detrending by segments was used, and the rare margin vegetation is often affected by the adjacent neigh- species were downweighted. Due to the rather long gradi- bouring phytocoenosis (Marshall & Arnold 1995). From the ents (4.118 SD units) in compositional turnover, a unimodal point of view of growing technology, the effect of agricultural CCA method (canonical correspondence analysis) was em- technology is more representative in the central field regions ployed. In CCA, gross and net effects of the explanatory than at the edges (Hald 1999) because the machinery traffic variables on weed species composition were determined. As is more frequent. The nomenclature follows that of Kubát explanatory variables, the management system (organic or et al. (2002). Fungi, non-vascular plants and self-seeded tree conventional), crop (winter cereals or root crops), and alti- seedlings have not been evaluated. tude were used. The statistical significance was tested using Factors influencing weed communities 445

Table 2. Gross and net eﬀects of explanatory variables on weed species composition.

Explanatory variables Eigenvaluea %b F-ratioc p-valued

All variables 0.498 10.6 7.77 0.002

Gross eﬀects Altitude 0.254 5.4 11.35 0.002 Crop 0.175 3.7 7.675 0.002 Management system 0.089 1.9 3.851 0.002

Net effects Altitude 0.237 5.1 11.097 0.002 Crop 0.156 3.3 7.289 0.002 Management system 0.086 1.8 4.007 0.002 asum of all canonical eigenvalues (total inertia = 4.681) bpercentage of explained variance cF-ratio for the test of significance of all (first) canonical axes dcorresponding probability value obtained by the Monte Carlo permutation test (499 permutations)

Table 3. Weed species with the highest fit in partial CCAs and their scores on the first canonical axis. Each column represents a separate pCCA where altitude, crop and management system were used in sequence as the explanatory variables. The effect of the other variables was excluded using them as covariables.

Altitude Ax 1 Fit Crop Ax 1 Fit Management system Ax 1 Fit (– low + high) score (– winter cereals + root crops) score (– organic + conventional) score

Chenopodium hybridum –0.98 0.119 Apera spica-venti –0.89 0.133 Stachys palustris –0.68 0.041 Amaranthus powellii –0.95 0.138 Lactuca serriola –0.73 0.072 Matricaria recutita –0.66 0.036 Descurainia sophia –0.91 0.088 Consolida regalis –0.70 0.053 Trifolium pratense –0.54 0.049 Amaranthus retroflexus –0.76 0.113 Silene noctiflora –0.61 0.052 Arabidopsis thaliana –0.53 0.042 Echinochloa crus-galli –0.75 0.128 Veronica arvensis –0.55 0.088 Silene noctiflora –0.53 0.039 Convolvulus arvensis –0.68 0.139 Myosotis arvensis –0.48 0.106 Erodium cicutarium –0.47 0.042 Chenopodium album –0.36 0.112 Galium aparine –0.41 0.097 Vicia hirsuta –0.38 0.036 Elytrigia repens 0.40 0.126 Polygonum aviculare –0.34 0.074 Myosotis arvensis –0.36 0.062 Veronica arvensis 0.56 0.093 Viola arvensis –0.31 0.059 Thlaspi arvense –0.32 0.084 Trifolium repens 0.58 0.085 Fallopia convolvulus –0.25 0.062 Tripleurospermum inodorum –0.21 0.046 Myosotis arvensis 0.60 0.170 Chenopodium album 0.36 0.113 Polygonum aviculare 0.21 0.029 Rumex obtusifolius 0.73 0.099 Plantago major 0.43 0.076 Fallopia convolvulus 0.24 0.057 Sonchus arvensis 0.84 0.179 Echinochloa crus-galli 0.61 0.087 Atriplex patula 0.44 0.021 Erodium cicutarium 0.90 0.156 Lycopsis arvensis 0.83 0.082 Viola arvensis 0.46 0.132 Vicia hirsuta 0.91 0.200 Solanum nigrum 0.83 0.060 Avena fatua 0.63 0.025 Arabidopsis thaliana 0.99 0.145 Amaranthus retroflexus 0.84 0.137 Brassica napus subsp. napus 0.90 0.115 Mentha arvensis 1.05 0.123 Spergula arvensis 0.89 0.049 Helianthus annuus 1.13 0.019 Lycopsis arvensis 1.13 0.151 Galinsoga quadriradiata 0.93 0.079 Aegopodium podagraria 1.38 0.020 Galeopsis tetrahit 1.20 0.312 Galinsoga parviflora 1.03 0.065 Beta vulgaris 1.40 0.067 Gnaphalium uliginosum 1.26 0.146 Neslia paniculata 1.25 0.063 Solanum tuberosum 1.54 0.027

Monte Carlo permutation tests. For the continuous vari- Results ables, the first canonical axis was tested, and for the nom- inal variables with more than two categories, all canonical In total, 189 weed species were found, some of which axes were tested (499 permutations were used). The gross can be considered as volunteers. Species richness dif- effects of the individual explanatory variables included the fered substantially among the fields, ranging from 0 to variation explained by other variables. The net effect of a 49 species per relevé. Species like Chenopodium album, particular variable was obtained by the exclusion of the effects that were shared with other variables. The net effects Viola arvensis, Fallopia convolvulus, Polygonum avicu- were tested using partial CCAs; here, one explanatory vari- lare, Cirsium arvense and Tripleurospermum inodorum able was used, and the others were used as covariables. The were most frequent in our dataset. ratio of a given canonical eigenvalue and the sum of all The combined environmental variables explained eigenvalues (total inertia) were used to estimate the pro- 10.6% of the variability. Based on the pCCAs, the high- portion of explained variation (Borcard et al. 1992). The est effect was found at altitude, which explained 5.1% scores along the first canonical axis for the weed species of the species composition variability. The second and with the highest fit in the analysis were listed for partial third most significant factors were crop and manage- CCAs (the species fit represents the percentage of variability in species values explained by the ordination subspace ment system, which explained 3.3% and 1.8% of the onto which the species scores are projected). CCA ordina- variability, respectively (Table 2). tion diagram showing species with the highest weight was Table 3 illustrates the species ranks along the main constructed (the species weight is equal to the sum of abun- gradients; only species with the highest fit are selected. dances of the species taken overall the samples). Chenopodium hybridum, Amaranthus powellii and De- 446 M. Kolářová et al.

Fig. 2. Ordination diagram of canonical correspondence analysis (CCA). The species with low weights (< 10 %) are not displayed. Ab- breviations: AETCY, Aethusa cynapium; AGRRE, Elytrigia repens;AMAPO,Amaranthus powellii;AMARE,Amaranthus retroflexus; ANGAR, Anagallis arvensis; APESV, Apera spica-venti;AVEFA,Avena fatua; BRSNN, Brassica napus subsp. napus;CAPBP, Capsella bursa-pastoris; CHEAL, Chenopodium album agg.; CHEHY, Chenopodium hybridum;CIRAR,Cirsium arvense; CONAR, Convolvulus arvensis; ECHCG, Echinochloa crus-galli; EPHHE, Euphorbia helioscopia;GAETE,Galeopsis tetrahit; GALAP, Gal- ium aparine; GERPU, Geranium pussilum;LAMPU,Lamium purpureum;MATIN,Tripleurospermum inodorum; MYOAR, Myosotis arvensis;PAPRH,Papaver rhoeas;PLAMA,Plantago major;POLAV,Polygonum aviculare agg.; POLCO, Fallopia convolvulus; POLLA, Persicaria lapathifolia;RUMOB,Rumex obtusifolius; SONAR, Sonchus arvensis;STEME,Stellaria media; TARSS, Tarax- acum spp.; THLAR, Thlaspi arvense; TRFRE, Trifolium repens;VERAR,Veronica arvensis; VERPE, Veronica persica;VICHI, Vicia hirsuta and VIOAR, Viola arvensis. scurainia sophia primarily occurred at altitudes < 250 cynapium, Avena fatua and species Galeopsis tetrahit, m a.s.l. Mentha arvensis, Lycopsis arvensis, Galeopsis Sonchus arvensis, Rumex obtusifolius, Vicia hirsuta, tetrahit and Gnaphalium uliginosum were typical of al- Myosotis arvensis, Veronica arvensis, were the typ- titudes > 350 m. The typical winter cereals species were ical species for low and high altitudes, respectively. Apera spica-venti, Lactuca serriola, Consolida regalis, Apera spica-venti, Papaver rhoeas, Tripleurospermum Silene noctiflora and Veronica arvensis. For root crops, inodorum, Taraxacum spp., Stellaria media, Polygonum species such as Galinsoga parviflora, Neslia paniculata, aviculare, Galium aparine, Viola arvensis were most Solanum nigrum, Amaranthus retroflexus and Spergula frequent in winter cereals while Chenopodium album, arvensis were representative. Species Stachys palustris, Echinochloa crus-galli, Amaranthus retroflexus and Matricaria recutita, Arabidopsis thaliana, Vicia hirsuta, Brassica napus subsp. napus volunteers in root crops. Myosotis arvensis and Thlaspi arvense characterised More species were related to organic farming compared the organically farmed fields. Weed species Viola ar- to conventional. High occurrence of Brassica napus vensis and Avena fatua, volunteers of Brassica napus subsp. napus volunteers was connected with conven- subsp. napus, Solanum tuberosum and Helianthus an- tionally grown root crops. nuus and weed beets (crossbreeds between wild and crop forms of Beta vulgaris) were typical in conven- Discussion tional fields. Figure 2 shows the ordination diagram CCA The composition of weed flora is determined by a large where only species with the highest weight are dis- number of environmental variables, and their relative played. Many of these species have the highest fit importance is often difficult to elucidate (Andersson & as well. Species Amaranthus spp., Chenopodium spp., Milberg 1998). In our study, altitude had the highest Echinochloa crus-galli, Convolvulus arvensis, Aethusa impact on the species composition of weed communi- Factors influencing weed communities 447 ties, besides the associated climatic and soil conditions and Consolida regalis, are typical for winter cereals, al- probably also due to the differences in farming inten- though many of them germinate not only in autumn sity at lower and higher altitudes. Obviously conditions but also throughout the year. Apera spica-venti was for agricultural production are more limited at higher the most significant winter cereal association, which elevations (generally smaller, steeper fields with more is a typical autumn germination weed and occurs in complex shapes make intensive mechanization, fertil- winter crops (Soukup et al. 2006). Hallgren et al. ization and pesticide application more difficult). Also, (1999) showed a strong link of Papaver rhoeas, Cen- Lososová et al. (2004) noticed the primary role of al- taurea cyanus, Consolida regalis and Apera spica-venti titude and associated climatic factors in weed species to winter crops, while Chenopodium album, Persicaria composition. They highlighted that the vegetation of lapathifolia, Spergula arvensis, Sinapis arvensis and a human-made habitat containing a large proportion Sonchus asper were linked to the spring cereals. An in- of alien species and strongly depending on manage- teresting trend is the occurrence of Lactuca serriola in ment, seems to be more influenced by primary environ- winter cereals. This species is not a typical field weed, mental factors than by human activities. Some other although it has increased in weed communities in re- most recent surveys indicated that the most impor- cent years and in many locations (Mikulka & Chodová tant factor in determining weed species composition in 2003). The affinity of winter crops is caused by the arable fields was the type of crop (Fried et al. 2008; biological characteristics of the species (i.e., annual Cimalová & Lososová 2009). The reason for such dif- or biennial species with winter character) and mainly ferences could be relatively small, homogenous survey spreads in the fields where minimum tillage is used, es- area in some works (Cimalová & Lososová 2009) or sig- pecially in winter cereals. Root crops are characterised nificantly different regional climatic conditions of these bytheweedsthatemergeinlatespringorearlysum- surveys. Crop is a more important factor in Southern merathighersoiltemperatures,suchasChenopodium Europe than in the Central and Northern part, as weed spp., Amaranthus spp., Echinochloa crus-galli, Galin- species in Southern Europe are in their optimal climatic soga spp. and Solanum nigrum. The biological charac- conditions (Holzner 1978). teristics of a species (dormancy) prevent germination in The management system, in the region up to now autumn, or possibly, their seedlings do not survive the rarely studied factor, affected the species composition of winter (Hallgren et al. 1999). Chenopodium album is of- weed communities less than other factors we analysed. ten described as a late-spring species; contrary to the This fact could be due to the relatively short organic other late-spring species, this species emerges on a mass management period of some companies, which is, thus, scale in very early spring (Kohout 1984) and generally not sufficiently long enough for the re-entry of certain can emerge throughout the year (Koch 1970). Lososová species from the field margins to the field centers. et al. (2006) found that the main differences between In our research, lowland localities were gener- the weed communities of root crops and cereals were ally characterised by thermally demanding annual a result of the root crop regular cultivation during the late-spring weed species, such as Amaranthus spp., vegetation period, while cereal crops were only culti- Echinochloa crus-galli and Chenopodium hybridum. vated at the beginning of vegetation and after harvest. The higher altitudes were represented by species that Such a statement is true only in part because in con- are characteristic for colder areas and poor, humid, ventional farming regular root crop cultivation during and acidic soil types, such as Cambisols (e.g., Gale- vegetation is currently applied only on certain farms opsis tetrahit, Gnaphalium uliginosum, Vicia hirsuta, in potatoes, while in sugar beet and maize have been Mentha arvensis and Lycopsis arvensis). In the Czech replaced by herbicide use. Contrastingly, harrowing in Republic the pH and nutrient status of soils is also cor- cereals during vegetation is used on organic farms. related with altitude, as base-rich soils are mainly found Conventionally cultivated areas are generally char- in dry lowlands. Therefore there is a clear distinction acterised by a narrow spectrum of recently significant between thermophilous, xerophilous and calcicole weed species that are often tolerant to herbicides (Viola ar- communities at low altitudes and communities of colder vensis). A higher proportion of species with wide eco- and wetter areas with acidic soils at higher altitudes logical amplitudes, such as Polygonum aviculare agg. (Lososová et al. 2004). Kropáč (1981) considered Gale- or Fallopia convolvulus and volunteers (e.g., Brassica opsis tetrahit, Vicia hirsuta and Arabidopsis thaliana as napus subsp. napus, Helianthus annuus and harvest species with relatively low ecological requirements, par- losses of Solanum tuberosum), is associated with in- ticularly regarding temperature and nitrogen content. tense cultivation of a narrow crop spectrum. Thus, Radics et al. (2000) identified Gnaphalium uliginosum when the principles of wide crop rotations are not as an indicator of cold conditions. Some weed species applied and agrotechnical errors that are caused by are indifferent to altitude, including Chenopodium al- economic pressure occur, the weed vegetation compo- bum agg. and Elytrigia repens. sition is affected and causesproblemswiththecul- Each crop is characterised by weed species with a tural plants that behave as undesirable components similar life cycle to the crop, particularly species with of weed communities. Crossbreeds of Beta species a similar germination period (Kohout 1988). The over- (weed beet) also possess a strong link to conven- wintering species, Apera spica-venti, Galium aparine, tional areas and currently cause difficulty for sugar Veronica arvensis, Myosotis arvensis, Viola arvensis beet growers (Soukup et al. 2002). Organic farms 448 M. Kolářová et al. do not usually grow sugar beet in the Czech Re- Hald A.B. 1999. Weed vegetation (wild flora) of long established public, and therefore, the weed beet was not found organic versus conventional cereal fields in Denmark. Ann. 134: here. Appl. Biol. 307–314. Hallgren E., Palmer M.W. & Milberg P. 1999. Data diving with In organically cultivated crops, certain species are cross-validation: an investigation of broad-scale gradients in sensitive to herbicides or, in general, intensive farm- Swedish weed communities. J. Ecol. 87: 1037–1051. ing (Hald 1999; Leeson et al. 2000). These species Holzner W. 1978. 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