Ecological Archives E088-076-A1

Ingrid M. Parker and Gregory S. Gilbert. 2007. When there is no escape: the effects of natural enemies on native, invasive, and noninvasive plants. Ecology 88:1210–1224.

Appendix A. Methodological details of common garden experiments for testing effects of pathogens and herbivores on native and introduced clover species.

This includes the following: (1) Details of methods and dates, (2) Table A1: Details of sample sizes, census dates, and harvest dates, and (3) Table A2: Number of individuals of each species surviving in final sample.

Details of methods and dates

In each year, we germinated seeds and then raised the seedlings in the Bodega Marine Reserve (BMR) greenhouse until plants were established. Plants were grown in Ray Leach Conetainers (2.5 cm × 16.5 cm, Stuewe and Sons, Corvallis, Oregon, USA) (Years 1–3) or plastic sleeves (Year 4) in soil collected in the field site, and watered with overhead misting, until transplanting into the field site.

Year 1. In 1997–1998, seeds were germinated in three cohorts from 19 November–14 December and grown in conetainers until transplanted into the field between 18 December–1 January. Plants that died were replaced until Feb. 7. Two plants of each species were randomized in 24 blocks (N = 48). Each block was at least 5 m from every other block, and plants were arranged every 0.5 m in rows 1 m apart. Deer netting was laid on top of the blocks. Seven blocks were used for severity censuses.

Year 2. In 1998–1999, seeds were germinated 15–19 December, grown in conetainers in the greenhouse, and transplanted into the field 6 February, replacing dead plants until 20 March. A 90-m × 105-m grid was laid out with posts every 15 m, providing 42 sites for blocks, of which 36 were used for this experiment. Each block had one plant from each species, randomized in three rows (1 m apart) of six plants (0.5 m apart). Deer netting was laid on top of the blocks. Seven blocks were used for severity censuses.

Year 3. In 1999–2000, seeds were planted into conetainers 17–21 December and transplanted into the field 2–4 February. We transplanted 40 pairs of control and fungicide plants per species into one large, randomized grid; pairs were 5 m apart in each direction, and plants in a pair were 0.3 m apart. The fungicide plants were sprayed weekly with DaconilTM + Tween 80; the control plants were sprayed with distilled water + Tween 80.

Year 4. In 2000–2001, intact soil cores were extracted in plastic sleeves 5 cm diameter and brought into the BMR greenhouse. Seeds were planted into these soil cores 13 January and transplanted into the field 13 March into their original holes, completely randomized for both species and fungicide treatment (6 replicates of each). Because they remained in plastic sleeves, these plants were protected from competition and belowground disturbance by gophers. The fungicide plants were sprayed weekly with Dithane F45TM + the surfactant RainguardTM; the control plants were sprayed with distilled water + RainguardTM.

TABLE A1. Details of sample sizes, census dates, and harvest dates for four years of common garden experiments. Year 3 and Year 4 included fungicide (F) and control (C) treatments.

 

Year 1

Year 2

Year 3

Year 4

 

1997–1998

1998–1999

1999–2000

2000–2001

Census dates for
disease prevalence

9Feb, 21Feb, 7Mar, 23Mar, 4Apr, 18Apr, 9May

5Feb, 20Feb, 7Mar, 20Mar, 3Apr, 17Apr, 1May, 15May, 22May

At harvest

At harvest

Census dates for
disease severity

8Mar, 21Mar, 3Apr, 17–20Apr, 18May

21Mar, 24Apr,
21May

At harvest

At harvest

Harvest dates

10–18 May

21–24 May

20–28 May

11–14 May

Number native species

9

10

8

9

Number introduced species

7

8

8

8

Number individuals
planted per species

48

34

40F + 40C

6F + 6C

 

TABLE A2. Number of individuals of each species surviving to the final sample. Year 3 and Year 4 include both fungicide and control plants in the sample size. The two invasive species are indicated in bold. A dash (–) indicates the species was not available for planting that year. Number of individuals planted per species is given in Table A1.

Origin

Species

Year 1

Year 2

Year 3

Year 4

Introduced

M. arabica

46

16

69

12

Introduced

M. lupulina

20

63

12

Introduced

M. polymorpha

38

20

63

12

Introduced

T. campestre

39

9

45

12

Introduced

T. dubium

37

12

55

11

Introduced

T. glomeratum

27

17

42

11

Introduced

T. repens

34

14

64

12

Introduced

T. subterraneum

42

17

63

12

Native

T. barbigerum

44

11

60

12

Native

T. bifidum

37

12

61

12

Native

T. fucatum

46

17

63

11

Native

T. gracilentum

32

13

60

12

Native

T. macraei

24

13

49

12

Native

T. microcephalum

39

6

45

12

Native

T. microdon

30

23

57

12

Native

T. variegatum

16

Native

T. willdenovii

35

17

12

Native

T. wormskjoldii

38

17

66

11



[Back to E088-076]