Table 1. Characteristics of the study sites: forest name, annual mean temperature (Tmean), annual precipitation, geographic location, site name, soil and humus type, dominant vegetation species, previous stand type and previous stand removal information. Climatic data are public data from Météo France.
Forest Tmean (°C) Precipitation (mm) Site Location Soil
type 		Humus
type 		Vegetation Previous stand type Stand removal type and date
Bord-Louviers 11 730 BL 49°18´N, 01°09´E Sandy-loamy Dysmoder Pteridium aquilinum 120-year-old Scots pine Windstorm 1999
Haguenau 10.4 758 H1 48°50´N, 07°55´E Sandy Mor Pteridium aquilinum >100-year-old mixed Scots pine, beech and pedunculate oak Windstorm 1999
H2 48°49´N, 07°55´E Sandy-loamy Hydromor Molinia caerulea >50-year-old mixed Scots pine and oak Windstorm 1999
H3 48°49´N, 07°53´E Sandy-loamy Hydromor Molinia caerulea 25 to 30-year-old Scots pine Windstorm 1999
Villecartier 11 850 VI 48°28´N, 01°33´W Loamy Mull Pteridium aquilinum >140-year-old beech Progressive regeneration cut 2010
Rennes 12 860 RE 48°13´N, 01°32´W Loamy Hydromor Molinia caerulea 180-year-old oak Progressive regeneration cut 2010
Escource 13.5 900 ES 44°12´N, 01°05´W Sandy Mor Pteridium aquilinum 50-year-old maritime pine Clear cut 2008
Solférino 13.5 900 SO 44°08´N, 00°53´W Sandy Hydromor Molinia caerulea 50-year-old maritime pine Clear cut 2008
Table 2. Description of the experimental sites: planted tree species, planting date, mechanical site preparation (MSP) treatment date, experimental design and characteristics of HE and RR treatments. Treatment names: DS+MS, deep scarifier followed by multifunction subsoiler; HE, herbicide; RR, regional reference. View in new window/tab.
Table 3. Survival after one growing season of pine and oak seedling planted in eight experimental sites in Northern France, in different site preparation treatments (HE, herbicide; RR, regional reference; DS, deep scarifier; DS+MS, deep scarifier followed by multifunction subsoiler; C, untreated control).
Site Tree species Vegetation Plantation
year 		Survival rate (%)
HE RR DS DS+MS C
BL Pinus nigra Pteridium aquilinum 2010 95 97 97 100 93
H1 Pinus sylvestris Pteridium aquilinum 2011 93 99 95 97 98
VI Pinus sylvestris Pteridium aquilinum 2011 93 87 98 94 64
ES Pinus pinaster Pteridium aquilinum 2011 50 61 62 62 44
H2 Pinus sylvestris Molinia caerulea 2011 99 99 100 100 95
H3 Pinus sylvestris Molinia caerulea 2011 99 97 100 100 79
RE Pinus sylvestris Molinia caerulea 2011 96 95 93 97 93
SO Pinus pinaster Molinia caerulea 2011 0 0 0 0 0
BL Quercus petraea Pteridium aquilinum 2010 97 98 94 96 93
H1 Quercus petraea Pteridium aquilinum 2011 69 68 24 2 43
H1 Quercus petraea Pteridium aquilinum 2012 89 86 89 85 77
VI Quercus petraea Pteridium aquilinum 2011 86 91 89 84 79
ES Quercus robur Pteridium aquilinum 2011 8 28 29 35 5
H2 Quercus petraea Molinia caerulea 2011 97 94 97 48 92
H2 Quercus petraea Molinia caerulea 2012 81 - - 85 -
H3 Quercus petraea Molinia caerulea 2011 87 80 85 25 91
H3 Quercus petraea Molinia caerulea 2012 75 - - 92 -
RE Quercus petraea Molinia caerulea 2011 98 97 96 98 98
SO Quercus robur Molinia caerulea 2011 58 70 88 82 67
Table 4. Survival after four growing seasons of pine and oak seedling planted in eight experimental sites in Northern France, in different site preparation treatments (HE2, HE3 and HE4 herbicide applied during 2, 3 and 4 growing seasons, respectively; RR, regional reference; DS, deep scarifier; DS+MS, deep scarifier followed by multifunction subsoiler; HE, herbicide; C, untreated control).
Site Tree species Vegetation Plantation
year 		Survival rate (%)
HE2 HE3 HE4 RR DS DS+MS C
BL Pinus nigra Pteridium aquilinum 2010 - 87 - 90 97 99 65
H1 Pinus sylvestris Pteridium aquilinum 2011 - - 76 67 68 91 51
VI Pinus sylvestris Pteridium aquilinum 2011 63 - - 73 91 90 40
H2 Pinus sylvestris Molinia caerulea 2011 - - 90 97 97 97 84
H3 Pinus sylvestris Molinia caerulea 2011 - - 93 89 91 97 56
RE Pinus sylvestris Molinia caerulea 2011 92 - - 89 89 96 79
BL Quercus petraea Pteridium aquilinum 2010 - 90 - 97 90 90 82
H1 Quercus petraea Pteridium aquilinum 2012 - - 84 57 79 78 47
VI Quercus petraea Pteridium aquilinum 2011 55 - - 84 85 75 56
H2 Quercus petraea Molinia caerulea 2011 - - 79 78 89 - 84
H2 Quercus petraea Molinia caerulea 2012 - - 70 - - 77 -
H3 Quercus petraea Molinia caerulea 2011 - - 72 66 78 - 66
H3 Quercus petraea Molinia caerulea 2012 - - 63 - - 87 -
RE Quercus petraea Molinia caerulea 2011 54 - - 50 46 89 57
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Fig. 1. Height and basal diameter of pine seedlings in Pteridium aquilinum sites (sites BL, H1 and VI, Northern France), following site preparation (HE: herbicide application; RR: regional reference; DS: deep scarifier; DS+MS: deep scarifier followed by multifunction subsoiler; C: untreated control). The horizontal arrow at the bottom of the graph indicates the length of time of herbicide application in treatment HE in each experimental site (from 2 to 4 years). The probability associated with the treatment effect is indicated in a linear model performed on height at the age of 4. Vertical segments on the right-hand side of the plot indicate the results of t-tests used for post-hoc mean comparisons (treatment means joined by a segment do not significantly differ).

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Fig. 2. Height and basal diameter of pine seedlings in Molinia caerulea sites (sites H2, H3 and RE, Northern France), following site preparation (HE: herbicide application; RR: regional reference; DS: deep scarifier; DS+MS: deep scarifier followed by multifunction subsoiler; C: untreated control). The horizontal arrow at the bottom of the graph indicates the length of time of herbicide application in treatment HE in each experimental site (from 2 to 4 years). The probability associated with the treatment effect is indicated in a linear model performed on height at the age of 4. Vertical segments on the right-hand side of the plot indicate the results of t-tests used for post-hoc mean comparisons (treatment means joined by a segment do not significantly differ).

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Fig. 3. Height and basal diameter of sessile oak seedlings in Pteridium aquilinum sites (sites BL, H1 and VI, Northern France), following site preparation (HE: herbicide application; RR: regional reference; DS: deep scarifier; DS+MS: deep scarifier followed by multifunction subsoiler; C: untreated control). The horizontal arrow at the bottom of the graph indicates the length of time of herbicide application in treatment HE in each experimental site (from 2 to 4 years). The probability associated with the treatment effect is indicated in a linear model performed on height at the age of 4. Vertical segments on the right-hand side of the plot indicate the results of t-tests used for post-hoc mean comparisons (treatment means joined by a segment do not significantly differ).

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Fig. 4. Height and basal diameter of sessile oak seedlings in Molinia caerulea sites (sites H2, H3 and RE; H2 and H3 were planted twice, Northern France), following site preparation (HE: herbicide application; RR: regional reference; DS: deep scarifier; DS+MS: deep scarifier followed by multifunction subsoiler; C: untreated control). The horizontal arrow at the bottom of the graph indicates the length of time of herbicide application in treatment HE in each experimental site (from 2 to 4 years). The probability associated with the treatment effect is indicated in a linear model performed on height at the age of 4. Vertical segments on the right-hand side of the plot indicate the results of t-tests used for post-hoc mean comparisons (treatment means joined by a segment do not significantly differ).

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Fig. 5. Plant cover in Pteridium aquilinum sites (sites BL, H1 and VI, Northern France) following site preparation (HE: herbicide application; RR: regional reference site preparation method; DS: deep scarifier; DS+MS: deep scarifier followed by multifunction subsoiler; C: untreated control). For each species, plant cover was estimated using Eq. 2. In treatment HE, the horizontal arrow at the top of the graph indicates the length of time of herbicide application in each experimental site (from 2 to 4 years). Plant species were pooled into seven groups. The asterisks above the first year in site BL correspond to a floristic inventory carried out soon after late frosts in May that reduced P. aquilinum cover. NA indicates missing values for the corresponding year.

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Fig. 6. Plant cover in Molinia caerulea sites (sites H2, H3, RE, Northern France) following site preparation (HE: herbicide application; RR: regional reference site preparation method; DS: deep scarifier, DS+MS: deep scarifier followed by multifunction subsoiler; C: untreated control). For each species, plant cover was estimated using Eq. 2. In treatment HE, the horizontal arrow at the top of the graph indicates the length of time of herbicide application in each experimental site (from 2 to 4 years). Plant species were pooled into seven groups. NA indicates missing values for the corresponding year.