I.W. Watson et al. (1997).Continuous and episodic components of demographic change in two Eremophilia species from arid Western Australia. Appendix 1

Population size following drought episodes [ t(1) ] as a proportion of population size before a drought episode [ t(0) ], for (a) total population size (b) existing plants only. Period is the length of time in years between t(0) and t(1) spanning the drought. Table, Figure and page numbers are those of the original Reference (Appendix 6). See Footnotes for more detail on individual cases. Approximate (~) values have been read from graphs rather than tables.
a/b	Species (site, if applicable)	Popn[t(1)] / Popn[t(0)]	t(0) - t(1)	Period (yrs)	Country	Reference (see Appendix 6)	Foot-note
a	Acacia aneura (>1 m height)	0.077	1964-71	6.8	Australia	Cunningham & Walker 1973 (Table 1b)	1
a	Menodora scabra (2 plots)	~0.15 & ~0.2	1948-59/60	11 & 12	USA	Goldberg & Turner 1986 (Fig. 4)	2
a	Atriplex vesicaria (>9 cm tall) (grazed & ungrazed)	~0.3. & ~0.33	6/80-10/83	3.3	Australia	Eldridge et al. 1990 (Fig. 2)	3
a	Atriplex vesicaria (total popn) (grazed & ungrazed)	~0.3. & ~0.48	6/80-10/83	3.3	Australia	Eldridge et al. 1990 (Fig. 2)	3
a	Acacia aneura (<1 m height)	0.312	1964-71	6.8	Australia	Cunningham & Walker 1973 (Table 1b)	1
a	Cassia sturtii (Quadrat 100)	~0.47	1947-61	14	Australia	Hall et al. 1964 (P 242)	4, 5
a	Opuntia versicolor (1 plot)	~0.6	1948-60	12	USA	Goldberg & Turner 1986 (Fig. 4)	2
a	Eremophila spectabilis (M20A) (grazed & ungrazed)	0.63 & 0.67	1976-79	3	Australia	Gardiner 1984 (Table 12); 1986a (Fig. 5)	6
a	Frankenia pauciflora (grazed & ungrazed)	0.79 & 0.79	1976-79	3	Australia	Gardiner 1984 (Table 12); 1986a (Fig. 5)	6
a	Eremophila forrestii (syn. E. leucophylla) (M18A, M19A), E. spectabilis (M18A), Maireana glomerifolia, Ptilotus obovatus (all grazed & ungrazed)	0.89 - 1.28	1976-79	3	Australia	Gardiner 1984 (Table 12); 1986 a (Fig. 5)	6
a	Maireana pyramidata (Scalded flat & sand dune)	~0.95 - ~1.3	1963-67	4	Australia	Milthorpe 1978 (Figs 1 & 2)
a	Maireana (syn. Kochia) sedifolia (nil, light, moderate, heavy, very heavy; grazing treatments)	0.95, 1.0, 0.98, 1.02, 0.91	1943-44	1	Australia	Trumble & Woodroffe 1954 (Table 3)	7
a	Calliandra eriophylla (1 plot)	~1.0	1948-59	11	USA	Goldberg & Turner 1986 (Fig. 4)	2
a	Maireana astrotricha (grazed & ungrazed)	~1.04 & ~1.09	6/80-10/83	3.3	Australia	Eldridge 1989 (Fig. 2.5)	8
a	Acacia aneura, A. colletioides, Callitris columellaris (syn. C. glaucophylla), Dodonaea viscosa, Eucalyptus populnea, Eremophila longifolia, E. mitchellii, E. sturtii, Myoporum deserti, Olearia pimeloides (plots 1, 2 grazed & 3, 4 ungrazed; all species pooled for each plot)	1.1, 1.2, 1.1, 1.0	9/64-6/69	4.8	Australia	Walker 1976 (Table 8.7)	9
a	Cercidium microphyllum (4 plots)	~1.0 - ~1.3	1948-59/60	11 - 12	USA	Goldberg & Turner 1986 (Fig. 4)	2
a	Maireana pyramidata (grazed & ungrazed)	~1.0 & ~1.3	6/80-10/83	3.3	Australia	Eldridge 1989 (Fig. 2.6)	8
a	Lycium berlandieri & L. fremontii (2 plots)	~1.0 & ~1.4	1948-60	12	USA	Goldberg & Turner 1986 (Fig. 4)	2
b	Atriplex vesicaria (Quadrat 10A)	0.00	1959-61	2	Australia	Crisp 1978 (P 522)	10
b	Encelia farinosa (2 cohorts & 2 plots)	~0 - ~0.2	1948-60	12	USA	Goldberg & Turner 1986 (Fig. 7)	11, 12
b	Encelia farinosa, Ferocactus cylindraceus, Atriplex canescans, Echinocactus polycephalus, Fouquieria splendens	0.00 - 0.25	1889/90-1990s	100-104	USA	Bowers et al. 1995 (Table 6 & Pp. 560-61)	13
b	Ambrosia deltoidea (3 cohorts & 3 plots)	~0 - ~0.7	1948-57/59/60	9-12	USA	Goldberg & Turner 1986 (Fig. 7)	11
b	Larrea tridentata (Permanent Larrea, Permanent Playa Plots pooled)	0.16	pre- 1959/60 -66	>7	Mexico	Turner 1990 (Table 5 & 7)	14
b	Krameria grayi (3 cohorts & 3 plots)	~0.3 - ~1.0	1948-57/59/60	9-12	USA	Goldberg & Turner 1986 (Fig. 7)	11
b	Acacia burkittii	0.33 & 0.33	1928- 37 & 70	9 & 40	Australia	Crisp & Lange 1976 (Fig. 5 & P 89)	15
b	Cercidium spp (Photogrammetic Carnegiea Plot)	0.35	1907-62	55	Mexico	Turner 1990 (Table 3)	16
b	Eremophila spectabilis (63A grazed)	0.37	1976-1979	3	Australia	Gardiner 1986b (Table 1)	17
b	Yucca angustissima, Ambrosia dumosa, Atriplex confertifolia, Opuntia basilaris, Opuntia erinacea	0.45 - 0.75	1889/90-1990s	100-104	USA	Bowers et al. 1995 (Table 6 & Pp. 558-60)	18
b	Atriplex vesicaria (grazed & ungrazed)	0.449 & 0.630	1975-83	8	Australia	Andrew & Lange 1986 (P 414)
b	Larrea tridentata (syn. L. divaricata) (3 cohorts & 2 plots)	~0.5 - ~1.0	1948-57/59/60	9-11	USA	Goldberg & Turner 1986 (Fig. 7)	11
b	Janusia gracilis (4 cohorts & 3 plots)	~0.5 - ~1.0	1948-59/60	11-12	USA	Goldberg & Turner 1986 (Fig. 7)	11, 19
b	Acacia aneura (Quadrats 200, 300, 6-80; Photopoint 12, 40A, 3; others, pooled)	0.56	1925-72	49	Australia	Crisp 1978 (Table 3)	4
b	Chrysothamnus nauseosus	0.78	1982-92	10	USA	Toft 1995 (P 4)	20
b	Acacia aneura (Quadrats 200, 300, 400, 6-80 pooled)	0.79	1926-62	36	Australia	Hall et al. 1964 (Table 1)	4
b	Myoporum platycarpum (Quadrats 100, 200, 300, 400 pooled)	0.79 & 0.41	1926-36 & 62	10 & 36	Australia	Hall et al. 1964 (Table 2)	4
b	Ephedra spp, Acacia greggii, Lycium andersonii, Larrea tridentata	0.83 - 0.99	1889/90-1990s	100-104	USA	Bowers et al. 1995 (Table 6 & P 557)	21
b	Carnegiea gigantea (Photogrammetic Carnegiea Plot)	0.84	1907-62	55	Mexico	Turner 1990 (Table 4)	16
b	Artemesia spinescens, Atriplex confertifolia, Ceratoides lanata (all 8 treatments)	0.85 - 1.0	1975-78	3	USA	Chambers & Norton 1993 (Fig. 1)	22
b	Maireana sedifolia (Photopoints 12 & 40A)	0.86 & 0.92	1931-72 & 72	41 & 46	Australia	Crisp 1975 (P 64); 1978 (Fig 3 & P 523)	4, 23
b	Eremophila forrestii (syn. E. leucophylla) (60A), E. spectabilis (19A), Frankenia pauciflora (62A), Ptilotus obovatus (59A) (all grazed)	0.86 - 0.92	1976-1979	3	Australia	Gardiner 1986b (Table 1)	17
b	Larrea tridentata (Photogrammetic Larrea Plot)	0.87	1907-62	55	Mexico	Turner 1990 (Table 2)	16
b	Rhagodia ulicina (grazed & ungrazed)	0.898 & 0.913	1975-83	8	Australia	Andrew & Lange 1986 (P 414)
b	Maireana sedifolia (grazed & ungrazed)	0.990 & 0.995	1975-83	8	Australia	Andrew & Lange 1986 (P 414)
b	Alectryon oleifolius (syn. Heterodendrum oleifolium) (Quadrats 100, 400, FR4 pooled)	0.91 & 0.68	1926-36 & 61	10 & 35	Australia	Hall et al. 1964 (Table 3)	4
b	Casuarina cristata	~0.97	1926-60	34	Australia	Hall et al. 1964 (P 233)	4, 24
b	Eremophila sturtii (Quadrats 100, 200, 300, 400, 6-80 pooled)	0.97 & 0.74	1926-36 & 60	10 & 34	Australia	Hall et al. 1964 (Table 4 & P 239)	4

Footnotes, Appendix 1 (Watson et al. 1997b)

1) This was the combined effect of two successive droughts. This scale of drought mortality appears unusual compared with reports of low A. aneura drought mortality (Melville 1947; Everist 1949; Hall et al. 1964; Crisp 1978; I. W. Watson & A. McR. Holm pers. obs.). In fact, Cunningham & Walker (1973) and Walker (1976) also reported on a nearby complementary study in which catastrophic death was not observed, only a few individuals of A. aneura died during the same two droughts.

2) This study was included even though sampling interval was long because of the protracted drought period. Small graph size made it difficult to calculate accurate estimates.

3) The drought was not regarded by Eldridge et al. (1990) as severe.

4) Hall et al. (1964), Crisp & Lange (1976) and Crisp (1978) all present data from the Koonamore Vegetation Reserve. Hall et al. provide data for many more species than presented here but in a manner unsuitable for precise calculation of drought effects. Three droughts were experienced between 1926 and 1962, with the most severe drought in the first 10 years. The end of the final drought coincided with the final sampling, therefore some additional mortality might be expected following a lag period.

5) This period (1947-1961) included three "drought years" (Hall et al. 1964) and the final "severe drought". Numbers in 1947 were a maximum, almost all of which had germinated since the 1930s.

6) All sites were destocked from sheep grazing. Half the plots were subsequently fenced to exclude red kangaroos. There was considerable between-site variation.

7) Densities estimated from 64 permanent plots each 40.5 m² (Woodroffe 1941) rather than cartographic data. The authors did not consider it a severe drought.

8) The same sites as footnote 3 over the same time period. The drought was not regarded by Eldridge as severe.

9) The same drought period as footnote 1 (Cunningham & Walker 1973) within the same region.

10) Ten out of ten individuals died, but all were more than 30 years old and came from a population considered to have a half-life of 11 years (Crisp 1978). Other, younger saltbushes survived more or less intact (Hall et al. 1964). A number of other A. vesicaria populations showed nil or minimal drought mortality (Figs 11 & 14, Hall et al. 1964), possibly because of the generally widespread and rapid regeneration of A. vesicaria throughout the Koonamore Vegetation Reserve. In fact, Wood (1936) observed increase in A. vesicaria populations on some plots during the 1932-36 drought although other plots recorded high mortality. Wood concluded that a "drought of extreme severity" would not kill a high proportion of the A. vesicaria ecotype found at Koonamore.

11) Six of the nine years between 1948 and 1957 were "extremely dry" including 1957, so that some drought induced mortality may not have been observed at the 1957 sampling. It is difficult to calculate accurate estimates from Figs 4 & 7 because of small graph size. Most cohorts contain less than 50 individuals, some less than 10. This summary does not include the 1948 cohort because of its young age.

12) This is a short-lived species with high turnover rate (Goldberg & Turner 1986). Total population remained stable (Plot 11) or increased (Plot 12) during this drought period.

13) These were classified as "moderate-lived plants" by Bowers et al. (1995). Drought was inferred both from the length of time and extrinsic knowledge (e.g. Kaibab deer incident)

14) The pre-drought numbers were inferred by Turner (1990) from "recently" dead individuals.

15) Fifteen individuals germinated in 1929. Ten died over the next 9 years (which included the most severe of the three droughts experienced at Koonamore: see Footnote 4) but the remaining 5 survived for at least another 30 years, which included the second drought reported in Hall et al. (1964).

16) The drought was assumed to be finished by 1962. The drought referred to by Turner (1990) was one of the most severe and protracted since 1700 (see Stahle & Cleaveland 1988)

17) These species X site combinations are additional to the whole population estimates given in Gardiner (1986a).

18) These were classified as "long-lived plants" by Bowers et al. (1995). Drought was inferred both from length of time and extrinsic knowledge (e.g. Kaibab deer incident)

19) The population density increased on all three plots over this time.

20) Sixty four percent of deaths (14% of initial population) occurred over a two year period.

21) These were classified as "very-long lived plants" by Bowers et al. (1995). Drought was inferred both from the length of the time period and extrinsic knowledge (e.g. Kaibab deer incident)

22) Adults only; seedlings and introductions were not summarised here.

23) Hall et al. (1964; Table 9) report survivorship of 9/16 (0.56) individuals over a 27 year period from Quadrats 300 and 40A, pooled.

24) Although multiple branching from the base made it difficult to determine individual trees, Hall et al. (1964) recorded "72+" trees still alive of an initial population of "74+".

British Ecological Society homepage