Ecological Archives A014-012-A2

Jeffrey R. Dunk, William J. Zielinski, and Haiganoush K. Preisler. 2004. Predicting the occurrence of rare mollusks in northern California Forests. Ecological Applications 14:713–729.

Appendix B. Means (±1 SD) of microscale variables that entered at least one of the “best” models for any of the five mollusk species with an Akaike weight >0.05.

Variables

Ancotrema voyanum

 

Helminthoglypta talmadgei

 

Monadenia churchi

 

Monadenia fidelis klamathica

 

Monadenia fidelis ochramphalus

 

Occupied

Absent

 

Occupied

Absent

 

Occupied

Absent

 

Occupied

Absent

 

Occupied

Absent

Pecentage Conifer Cover

58.17 (29.20)

54.50 (29.13)

 

36.63 (32.53)

56.44 (30.28)

 

50.20 (31.51)

48.30 (31.59)

 

67.11 (26.68)

48.38 (28.82)*

 

50.88 (33.42)

57.00 (30.11)

Percentage Hardwood Cover

59.88 (40.89)

43.33 (39.77)

 

51.25 (32.50)

50.29 (41.87)

 

57.78 (40.23)

31.66 (39.24)*

 

71.89 (35.46)

39.81 (42.14)**

 

72.50 (27.11)

37.44 (39.58)**

Percentage Grass Cover

3.00 (5.71)

7.68 (13.35)**

 

15.13 (12.99)

3.93 (6.24)**

 

5.51 (7.34)

7.65 (11.65)

 

2.78 (4.97)

4.32 (8.00)

 

4.88 (5.17)

4.89 (8.26)

Conifer Basal Area

42.58 (23.20)

29.68 (21.91)**

 

20.92 (20.89)

31.48 (19.65)

 

26.82 (20.24)

25.93 (19.96)

 

34.46 (16.21)

27.07 (21.88)

 

25.39 (15.68)

33.60 (21.44)

Hardwood Basal Area

13.89 (11.70)

10.10 (12.30)

 

6.57 (6.33)

11.02 (11.46)

 

11.42 (10.66)

6.26 (9.26)**

 

23.67 (18.44)

10.00 (12.70)*

 

13.94 (7.39)

8.84 (12.57)

Quercus Basal Area

0.38 (0.74)

1.13 (2.07)*

 

1.37 (0.78)

0.90 (1.75)

 

2.17 (2.58)

1.23 (2.35)**

 

1.16 (1.71)

0.45 (1.45)

 

0.65 (0.70)

0.57 (1.40)

Acer Basal Area

0.13 (0.28)

0.16 (1.12)

 

0.01 (0.02)

0.04 (0.12)

 

0.08 (0.29)

0.11 (1.01)

 

0.11 (0.33)

0.05 (0.19)

 

0.16 (0.35)

0.04 (0.17)

Mean Tree Age

185.66 (63.86)

124.74 (75.37)**

 

94.91 (76.27)

140.93 (60.35)

 

107.23 (63.06)

115.39 (71.39)

 

142.82 (56.58)

133.09 (83.44)

 

150.22 (98.82)

129.60 (74.50)

Standard Deviation of Tree Age

94.25 (56.04)

74.74 (54.55)

 

45.89 (52.41)

76.69 (45.14)

 

61.47 (43.98)

65.32 (56.58)

 

84.71 (24.60)

70.94 (62.64)

 

67.01 (57.46)

70.39 (57.09)

Mean Conifer Diameter

68.84 (19.57)

45.99 (23.87)**

 

51.65 (19.86)

53.25 (18.30)

 

41.34 (16.87)

43.85 (19.50)

 

47.57 (22.24)

46.71 (26.69)

 

54.35 (27.28)

49.38 (21.62)

Mean Hardwood Diameter

19.32 (15.33)

19.32 (15.41)

 

19.88 (6.92)

15.12 (13.24)

 

17.91 (13.59)

15.84 (18.65)

 

19.32 (6.21)

13.39 (12.73)**

 

19.62 (7.60)

13.67 (11.10)*

Mean Hardwood Height

9.50 (6.52)

8.81 (5.87)

 

9.57 (1.97)

6.84 (5.22)**

 

6.97 (4.11)

5.94 (6.52)

 

12.80 (2.63)

7.12 (6.05)**

 

9.45 (2.65)

7.26 (5.51)*

Volume of Large Downed Wood

66.87 (52.16)

47.36 (63.06)

 

20.40 (24.09)

36.82 (44.05)

 

32.34 (36.81)

27.86 (29.57)

 

23.48 (23.00)

46.11 (54.11)*

 

51.28 (46.15)

48.10 (57.86)

Volume of Small Downed Wood

17.56 (7.25)

13.68 (6.96)**

 

13.06 (5.50)

13.67 (7.39)

 

14.08 (7.65)

14.06 (8.66)

 

13.77 (6.54)

13.50 (6.64)

 

12.79 (6.39)

15.45 (7.26)

Total Volume of Downed Wood

84.43 (53.22)

61.04 (65.04)*

 

33.47 (24.05)

50.49 (47.65)

 

46.43 (38.83)

41.92 (34.75)

 

37.25 (24.10)

59.60 (56.30)*

 

64.06 (46.32)

63.54 (60.60)

Transformed Aspect

0.39 (0.37)

0.51 (0.38)

 

0.69 (0.28)

0.49 (0.36)*

 

0.55 (0.33)

0.51 (0.37)

 

0.36 (0.38)

0.45 (0.38)

 

0.40 (0.40)

0.46 (0.37)

Percentage Slope

51.25 (19.85)

47.38 (19.89)

 

56.25 (15.06)

50.73 (20.90)

 

49.45 (18.20)

41.86 (16.69)*

 

46.67 (20.62)

48.53 (19.57)

 

47.50 (14.88)

49.86 (19.38)

Elevation (m)

975.61 (341.04)

986.50 (385.75)

 

952.74 (213.57)

1135.48 (470.23)*

 

1048.78 (404.83)

1285.27 (419.08)**

 

718.16 (343.28)

947.81 (376.13)*

 

788.87 (192.43)

1040.45 (432.54)**

Mean Annual Precipitation

166.82 (35.16)

162.88 (43.66)

 

119.11 (17.86)

149.79 (34.50)**

 

139.75 (34.96)

139.54 (28.25)

 

169.65 (35.64)

206.27 (56.27)**

 

154.15 (23.68)

165.56 (55.67)

Mean Summer Precipitation

7.88 (0.20)

7.90 (0.28)

 

7.67 (0.13)

7.82 (0.21)**

 

7.65 (0.24)

7.66 (0.31)

 

7.90 (0.23)

8.16 (0.37)**

 

7.82 (0.12)

8.00 (0.31)**

CVPRE

95.82 (0.90)

95.31 (1.65)*

 

94.00 (1.66)

94.67 (1.53)

 

95.43 (2.11)

95.12 (2.02)

 

96.10 (0.75)

95.28 (1.40)**

 

95.45 (0.70)

93.87 (2.82)**

Mean August Maximum Temperature

31.38 (1.45)

30.40 (2.49)**

 

31.46 (1.26)

30.54 (2.27)

 

30.72 (1.54)

29.75 (2.51)**

 

32.48 (0.89)

29.34 (2.97)**

 

31.62 (1.29)

29.03 (2.84)**

Mean December Minimum Temperature

-1.98 (0.91)

-2.14 (1.33)

 

-2.65 (1.30)

-3.45 (2.01)

 

-3.22 (1.76)

-3.78 (1.88)*

 

-0.97 (1.40)

-1.39 (1.26)

 

-1.39 (0.99)

-2.24 (1.28)**

August Max. Temp -  Dec. Min. Temp.

33.36 (1.28)

32.54 (2.53)**

 

34.11 (0.36)

33.99 (0.79)

 

33.94 (0.93)

33.53 (1.04)**

 

33.45 (0.72)

30.73 (3.25)**

 

33.01 (1.19)

31.27 (2.94)**

Mean Summer Temperature

17.72 (1.00)

17.04 (1.43)**

 

17.50 (1.24)

16.76 (1.88)

 

16.74 (2.05)

15.99 (2.02)**

 

18.77 (0.87)

16.97 (1.53)**

 

18.25 (0.86)

16.67 (1.55)**

SMRTSMRP

81.19 (3.51)

79.53 (4.98)*

 

82.82 (3.63)

79.42 (5.89)*

 

81.27 (4.825)

79.60 (7.06)*

 

83.39 (4.05)

76.96 (6.21)**

 

82.99 (2.01)

77.71 (5.27)**

Young forest†

0

23

 

1

8

 

13

30

 

1

20

 

0

22

Mature forest†

11

42

 

5

24

 

34

56

 

5

30

 

5

30

Old-growth forest†

13

  19‡

 

2

9

 

8

13

 

3

18

 

3

20

   Note: The last three rows represent the number of plots classified as young, mature, or old-growth forest by a modified version of the model developed by Bingham and Sawyer (1991).

†The Discriminant Function Analysis (DFA) model developed by Bingham and Sawyer (1991) used eight variables. We had available to us four of those variables from the Forest Inventory and Analysis data (basal area of conifers > 90 cm dbh; basal area of conifers >45 cm dbh; density of hardwood snags > 20 cm dbh; and basal area of hardwoods 45-90 cm dbh). Bruce Bingham (USDA Forest Service, Region 6) re-ran the original data from Bingham and Sawyer (1991) with this reduced variable set, then used the resulting model to classify the FIA plots within our study area. The reduced-variable DFA model had jack-knifed correct classification rates of 86% for young and mature forests, and 97% for old-growth forests using their original data. We conducted a chi-square goodness-of-fit test to evaluate the association of each species to young, mature, and old-growth forests using this classification. 

‡=significant association ( = 12.91, df = 4, P = 0.044), primarily due to fewer plots than expected in young forest being occupied and more plots in old-growth forest than expected being occupied.

  *  =  P < 0.10, ** = P < 0.05. 

 

Literature cited

Bingham, B. B., and J. O. Sawyer. 1991. Distinctive features and definitions of young, mature, and old-growth Douglas-fir/hardwood forests. Pages 363–378 in L. F. Ruggerio, K. B. Aubry, A. B. Carey, and M. H. Tuff, Technical Coordinators. Wildlife and vegetation of unmanaged Douglas-fir forests. U.S. Department of Agriculture, Forest Service, General Technical Report PNW-GTR-285, Portland, Oregon, USA.



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