‘Biovigilance Flore’: a weed monitoring system in France
In 2002, a survey of weeds in arable crops was set up accross France by the National Plant Protection Organization (network ‘Biovigilance Flore’), which is meant to be a long term project. The primary objective of this survey is to detect and document any change in weed flora due to modifications in cultivation methods (new herbicides, GMO crops, no-tillage systems, etc.). The survey is carried out across 1000 fields chosen to represent the diversity of cultural practices and environmental conditions in arable fields in France. In each field, a ‘relevé’ of all vascular plant species is performed, over a representative area of 2000 m² (40 m x 50 m) and using six cover classes to measure the abundance of each plant. Relevant data about management practices and ecological conditions are also collected. Moreover, a control plot, located in an untreated area adjacent to the survey area, is also surveyed to identify the potential flora (i.e. weeds that would occur if no herbicides were sprayed).
Between 2002 and 2004, ‘Biovigilance Flore’ recorded the presence of about 310 taxa which are considered to be representative of the weed flora in France. The total number of weed species per plot (control plot + treated area) varies from 1 to 58 with a median value of 12 and an average of 13.2 (+/- 0.4). In the treated area, the average number of weed species per field is only 4.2, and 135 plots (about 8%) no longer had any weed species. The untreated control plot area counts 8.5 weed species i.e. about twice as many species as the treated plots. Beyond this brief overview, the richness of the dataset enables: (1) to determine the relative influence of environmental and management factors on weed species composition and (2) to describe and search the underlying ecological rules of weed flora shifts.
(1) Determining the relative influence of environmental and management factors on weed species composition and diversity
A multivariate analysis of data from approximately 700 arable fields was carried out to determine the respective importance of environmental factors and management practices on weed species richness and composition.
This analysis indicated that the major variations in species composition between fields were associated with the following factors (ordered by importance):
- crop management: firstly the current crop type and secondly the preceding crop type. Three main weed communities were identified according to sowing periods: winter, spring and summer crops.
- soil pH and texture to a lesser degree, resulting in highly contrasting weed communities on basic clay soils compared to those on acidic sandy soils.
- climate and geographical position (mainly precipitation and longitude, surprisingly the influence of temperature and latitude was less pronounced).
Species richness also depends on landscape organisation and/or tillage depth. Species richness was 33 % higher in fields located in diversified landscapes surrounded by hedges and meadows than in fields located in open areas, showing that increased landscape complexity enhances species diversity in arable fields. These results open up possibilities for cropping systems with reduced impacts on plant diversity.
(2) Monitoring and analysing shifts in weed flora
This monitoring, conducted over large spatial and temporal scales, allows regular updates of the distribution of weed species in France and the identification of the most problematic species in each crop. An initial review of changes that occurred since the 1970s was undertaken in the five main crop species (maize, oilseed rape, sugarbeet, sunflower and winter wheat).
- Increasing arable weed species
The most successful species nowadays are Mercurialis annua, Lolium spp., Senecio vulgaris, Cirsium arvense and Sonchus asper that have increased in (almost) all crop types. The large ecological range of these species combined with their ability to make effective use of high nitrogen input and to disperse in the landscape could explain that they have been able to cope with several aspects of agricultural intensification (herbicides, higher amount of fertilizer, competition with the crop, changes in crop rotation, no-tillage systems, etc.).
Some species only increased or decreased in one crop type.;These cases often correspond to species favoured by the lack of herbicide selectivity, e.g. Aethusa cynapium in sugarbeet, Datura stramonium in sunflower, etc.
|
Species and Family
|
GCW
|
Winter
wheat |
Oilseed
rape |
Sugar-
beet |
Sun-flower
|
Maize
|
|
Aethusa cynapium
(Apiaceae)
|
AW, W
|
|
|
+ (N)
|
|
|
|
Amaranthus retroflexus #
(Amaranthaceae)
|
AW, EW, NW, W
|
|
|
=
|
+ (N)
|
=
|
Calystegia sepium(Convolvulaceae)
|
AW, EW, NW, W
|
|
|
|
|
+ (N)
|
Capsella bursa-pastoris(Brassicaceae)
|
AW, EW, NW, W
|
+
|
=
|
-
|
=
|
+ (N)
|
Chenopodium album(Chenopodiaceae)
|
AW, EW, NW, W
|
+
|
+ (N)
|
-
|
+
|
=
|
|
Chenopodium polyspermum
(Chenopodiaceae)
|
AW, EW, W
|
|
|
|
|
+ (N)
|
Cirsium arvense(Asteraceae)
|
AW, EW, NW, W
|
+
|
+ (N)
|
+ (N)
|
+ (N)
|
- (D)
|
|
Convolvulus arvensis
(Convolvulaceae)
|
AW, EW, NW, W
|
|
|
+ (N)
|
=
|
=
|
Datura stramonium #(Solanaceae)
|
AW, EW, NW, W
|
|
|
|
+ (N)
|
|
Daucus carota(Apiaceae)
|
AW, EW, NW, W
|
|
|
|
+ (N)
|
|
|
Euphorbia helioscopia
(Euphorbiaceae)
|
AW, EW, NW, W
|
|
|
|
+ (N)
|
|
|
Galium aparine subsp. aparine
(Rubiaceae)
|
AW, EW, NW, W
|
+
|
=
|
=
|
=
|
|
Geranium dissectum(Geraniaceae)
|
AW, EW, W
|
+ (N)
|
+ (N)
|
|
|
|
|
Kickxia spuria + elatine
(Scrophulariaceae)
|
AW, EW, W
|
|
|
=
|
=
|
+ (N)
|
|
Lamium purpureum
(Lamiaceae)
|
AW, EW, W
|
+
|
=
|
|
|
+ (N)
|
Lapsana communis(Asteraceae)
|
AW, EW, W
|
+
|
+ (N)
|
|
|
|
|
Lolium spp.
(Poaceae) |
AW, EW, W
|
+
|
+
|
+ (N)
|
+ (N)
|
|
|
Mercurialis annua
(Euphorbiaceae)
|
AW, EW, W
|
+ (N)
|
+
|
+
|
+
|
+
|
Myosotis arvensis(Boraginaceae)
|
AW, EW, W
|
+
|
+
|
|
|
|
|
Panicum milliaceum
(Poaceae)
|
AW, EW, NW, W
|
|
|
|
|
+ (N)
|
Poa annua(Poaceae)
|
AW, EW, NW, W
|
+
|
=
|
|
|
+ (N)
|
|
Polygonum persicaria + lapathifolium
(Polygonaceae)
|
AW, EW, NW, W
|
|
+ (N)
|
=
|
+
|
=
|
|
Senecio vulgaris
(Asteraceae)
|
AW, EW, NW, W
|
+ (N)
|
+
|
|
+ (N)
|
+ (N)
|
|
Setaria verticillata + viridis
(Poaceae)
|
AW, EW, NW, W
|
|
|
|
+ (N)
|
=
|
Solanum nigrum(Solanaceae)
|
AW, EW, NW, W
|
|
+ (N)
|
=
|
+
|
+
|
|
Sonchus asper + oleraceus
(Asteraceae)
|
AW, EW, NW, W
|
+ (N)
|
+ (N)
|
=
|
+
|
+ (N)
|
|
Taraxacum officinale
(Asteraceae)
|
AW, EW, NW, W
|
+
|
|
|
|
|
|
Viola arvensis*
(Violaceae)
|
AW, EW, W
|
+
|
+
|
=
|
- (D)
|
=
|
Legend: + (increasing species);; = (stable species);; - (decreasing species);; + (N) (increasing species not recorded among the top 25 weed species in the 1970s, i.e. dramatic species increase);; - (D) (decreasing species no longer recorded in the top 25 weed species in the 2000s, i.e. dramatic species decline); * characteristic segetal weed species ; # neophyt species (introduced in France after 1500).
Abbreviations for the Global Compendium of Weeds column:
W: Weed; N: Noxious Weed; EW: “Environmental Weed”; AW: “Agricultural weed”
- Decreasing arable weed species
Herbicides can also be responsible for the decrease of some sensitive species in particular crops: Legousia speculum-veneris, Ranunculus arvensis and Ranunculus sardous in winter wheat, Spergula arvensis and Galinsoga parviflora in maize, Anagallis arvensis in sugarbeet, etc.
It should be kept in mind that even if the frequency and abundance of some species is considered to be decreasing, these species could however remain major weeds (e.g., Alopecurus myosuroides, Papaver rhoeas or Veronica hederifolia in winter crops; Polygonum aviculare or Fallopia convolvulus in spring crops) or could be considered to be serious weeds in particular conditions e.g. Digitaria sanguinalis and Setaria pumila in maize monoculture in Aquitaine.
|
Species and Family
|
GCW
|
Winter
wheat |
Oilseed
rape |
Sugar-
beet |
Sun-flower
|
Maize
|
|
Alopecurus myosuroides*
(Poaceae) |
AW, EW, NW, W
|
-
|
-
|
-
|
-
|
|
|
Anagallis arvensis
(Primulaceae)
|
AW, EW, W
|
- (D)
|
|
-
|
-
|
=
|
|
Anthemis arvensis* + cotula
(Poaceae) |
AW, EW, NW, W
|
- (D)
|
|
|
|
|
Apera spica-venti*(Poaceae)
|
AW, W
|
- (D)
|
|
|
|
|
|
Aphanes arvensis*
(Rosaceae) |
AW, EW, W
|
-
|
-
|
|
|
|
|
Arabidopsis thaliana
(Brassicaceae)
|
AW, W
|
- (D)
|
- (D)
|
|
|
|
|
Avena sterilis subsp. ludoviciana
(Poaceae)
|
AW, W
|
- (D)
|
- (D)
|
|
|
|
|
Cerastium spp.
(Caryophyllaceae) |
AW, EW, W
|
-
|
=
|
|
|
|
|
Digitaria sanguinalis
(Poaceae)
|
AW, EW, NW, W
|
|
|
|
|
-
|
|
Elytrigia repens
(Poaceae)
|
AW, EW, NW, W
|
|
- (D)
|
|
- (D)
|
- (D)
|
Euphorbia exigua(Euphorbiaceae)
|
AW, W
|
|
|
- (D)
|
|
|
|
Fallopia convolvulus
(Polygonaceae)
|
AW, EW, W
|
-
|
|
=
|
-
|
-
|
|
Fumaria officinalis
(Fumariaceae)
|
AW, EW, W
|
=
|
=
|
=
|
- (D)
|
- (D)
|
|
Galinsoga parviflora #
(Asteraceae) |
AW, EW, NW, W
|
|
|
|
|
- (D)
|
|
Lamium amplexicaule
(Lamiaceae)
|
AW, EW, NW, W
|
|
|
|
- (D)
|
|
|
Legousia speculum-veneris*
(Campanulaceae)
|
AW, W
|
- (D)
|
|
|
|
|
|
Matricaria recutita + perforata
(Asteraceae)
|
AW, EW, NW, W
|
-
|
-
|
=
|
=
|
=
|
|
Papaver rhoeas*
(Papaveraceae)
|
AW, EW, W
|
-
|
-
|
=
|
|
|
Picris echioides(Asteraceae)
|
AW, EW, W
|
|
|
|
- (D)
|
|
|
Polygonum aviculare
(Polygonaceae)
|
AW, EW, NW, W
|
-
|
|
-
|
-
|
=
|
|
Portulaca oleracea
(Portulacaceae)
|
AW, EW, NW, W
|
|
|
|
|
- (D)
|
|
Ranunculus arvensis*
(Ranunculaceae)
|
AW, EW, W
|
- (D)
|
|
|
|
|
|
Ranunculus sardous
(Ranunculaceae)
|
AW, EW, W
|
- (D)
|
|
|
|
|
|
Raphanus raphanistrum
(Brassicaceae)
|
AW, EW, NW, W
|
-
|
=
|
=
|
- (D)
|
- (D)
|
|
Setaria pumila
(Poaceae)
|
AW, EW, NW, W
|
|
|
|
|
- (D)
|
|
Sinapis arvensis
(Brassicaceae)
|
AW, EW, NW, W
|
=
|
+
|
-
|
-
|
|
|
Sonchus arvensis
(Asteraceae)
|
AW, EW, NW, W
|
|
|
- (D)
|
|
|
|
Spergula arvensis*
(Caryophyllaceae)
|
AW, EW, NW, W
|
|
- (D)
|
|
|
- (D)
|
|
Stellaria media
(Caryophyllaceae)
|
AW, EW, NW, W
|
=
|
-
|
-
|
- (D)
|
+
|
|
Valerianella spp.*
(Valerianaceae)
|
AW, EW, W
|
- (D)
|
|
|
|
|
|
Veronica hederifolia
(Scrophulariaceae)
|
AW, EW, W
|
=
|
-
|
=
|
|
|
|
Veronica persica # + polita
(Scrophulariaceae)
|
AW, EW, W
|
-
|
- (D)
|
- (D)
|
(-D)
|
+ (N)
|
The use of herbicides cannot explain all changes observed. Other characteristics of weed species (life cycle, competitiveness, etc.) could also be important and should be analyzed through a functional group approach. A functional group gathers a set of plants sharing common biological characteristics as well as common ecological behaviour and/or effects on ecosystem processes. A study conducted in sunflower crops highlighted that nearly two thirds of the increasing species belonged to a single functional group. These species were taller and more nitrophilous (i.e. more competitive), more heliophilous, less sensitive to sunflower herbicides and shared a rapid summer life cycle. In other words, the weed flora occurring in sunflower crops has specialised since the 1970s in favour of ‘sunflower mimicking’ species.
Due to crop rotation, the success of a species in one crop could also have an impact on the following crops in the rotation. For instance, Geranium dissectum increased in winter wheat (although it is well controlled by herbicides in this crop), probably because of its success in oilseed rape which generally precedes winter wheat in the rotation. Some crops can thus be considered as a gateway for ‘new’ weeds in cultivated fields (e.g. oilseed rape for Geranium spp. or Sisymbrium officinale; sunflower for Ambrosia artemisiifolia ; maize for Panicum spp.).
Some ‘new’ weeds such as Ambrosia artemisiifolia, Orobanche ramosa, Cuscuta spp. are monitored through the ‘Biovigilance Flore’ network. Nevertheless, the low density of surveyed fields is unlikely to allow the early detection of new invasive plants.
Sources
Contact;: Guillaume Fried, LNPV, FR or Xavier Reboud, INRA, FR. E-mail: fried@supagro.inra.fr ; reboud@dijon.inra.fr
Fried G, Bombarde M, Delos M, Gasquez J, Reboud X (2005) Les mauvaises herbes du maïs : ce qui a changé en 30 ans. Phytoma-La Défense des Végétaux no. 586, 47-51.
Fried G, Reboud X (2007) Evolution de la composition des communautés adventices des cultures de colza sous l’influence des systèmes de cultures. Oléagineux, Corps Gras, Lipides 14, 130-138.
Fried G, Reboud X, Gasquez J, Delos M (2007) Le réseau ‘Biovigilance Flore’ : Présentation du dispositif et première synthèse des résultats. Vingtième conférence du Columa. Journées internationales sur la lutte contre les mauvaises herbes. Dijon, France, 2007-12-11/12, 315-325.
Fried G, Chauvel B, Reboud X. A functional analysis of large-scale temporal shifts in the sunflower weed assemblages in France between 1970 and 2000. Journal of Vegetation Science, in press.
Fried G, Norton LR, Reboud X. Environmental and management factors determining weed species composition and diversity in France. Agriculture, Ecosystems ; Environment, in press.