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The Distribution of Organisms in Time

  • M. B. Usher

Abstract

The processes with which biological conservation is concerned extend over many time scales, from the diurnal variations in the position or response of a population to the long-term changes in which a species may enter and leave a community during the successional process. A statistical approach to these situations is by the techniques of time series analysis, time series being defined as sets of observations taken at specified times, usually at equal intervals. The time series represented in Table 2.1 is artificial, but it can be taken to be the monthly catches of a moth species in a light trap during a 20-year period. The two immediate observations that can be made from the data are first that the moth occurs seasonally, and secondly that it has two generations per year which are on the wing in May and during August and September. This is particularly clearly seen when the data are plotted as a graph of monthly catch against time, see Fig. 2.1 (a).

Table 2.1

Artificial data for the monthly totals of a moth species caught in a light trap

Year

Months

           
 

J

F

M

A

M

J

J

A

S

O

N

D

1951

0

1

0

5

17

12

4

27

13

3

0

0

1952

0

0

0

1

23

10

2

19

24

6

1

0

1953

1

0

1

7

14

12

9

19

20

4

0

0

1954

0

0

1

6

45

9

1

3

14

2

0

0

1955

0

1

1

6

45

9

1

3

14

2

0

0

1956

0

1

3

12

13

2

5

24

10

0

0

0

1957

0

0

0

8

9

3

4

26

13

7

3

1

1958

0

0

1

4

12

7

3

13

23

10

0

0

1959

0

1

2

5

18

5

15

26

6

1

0

0

1960

0

0

0

5

21

5

6

22

15

0

0

0

1961

0

0

1

7

12

3

0

6

33

7

0

0

1962

1

0

0

3

23

3

2

17

14

5

1

0

1963

0

0

2

12

11

0

6

32

10

0

0

0

1964

0

0

0

1

16

2

3

27

12

6

3

1

1965

0

0

2

6

18

0

4

15

27

5

1

0

1966

1

1

2

8

14

5

6

12

23

4

1

0

1967

0

0

0

0

16

13

0

22

18

5

0

0

1968

0

0

1

6

9

3

8

12

18

6

0

0

1969

0

0

1

3

15

7

5

18

11

3

1

0

1970

0

0

2

9

7

0

11

21

16

1

0

0

Keywords

Ripe Seed Weather Type Snow Surface Photoperiodic Response Cyclical Movement 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© M. B. Usher 1973

Authors and Affiliations

  • M. B. Usher
    • 1
  1. 1.University of YorkUK

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