Demographic structure of three species of Sarcocapnos (Fumariaceae) as a basis for their conservation

The genus Sarcocapnos DC., endemic to the western Mediterranean basin, contains seven species, all of which are rare. Monthly monitoring of the number and flowering status of individuals as well as the appearance of new seedlings in five populations of three species, Sarcocapnos baetica (Boiss. & Reuter) Nyman, Sarcocapnos enneaphylla (L.) DC., and Sarcocapnos pulcherrima Morales & Romero-Garcia, was conducted between July 1997 and June 1998. This monitoring was repeated in May 1999 and 2000. Given the difficulty in establishing the age of individuals, those that did not produce flowers in the study period were considered juveniles, and reproductive individuals that wilted for no apparent external cause were deemed senescent. Sarcocapnos enneaphylla has a short life-span, early sexual maturity, and high seedling production. This combination appears to be highly effective, because the species is widely distributed geographically with many populations. In contrast, S. pulcherrima and S. baetica have longer life-spans, delayed sexual maturity, and lower production of seedlings. The low recruitment rate in these two species is offset by a long life expectancy among reproductive individuals, although this strategy apparently limits their capacity for geographical expansion. The equilibrium growth rate (lambda) varied markedly in S. enneaphylla populations (SE-1: lambda = 0.570 for 1997-1998 to 1998-1999 and lambda = 1.226 for 1998-1999 to 1999-2000; SE-2: lambda = 0.832 for 1997-1998 to 1998-1999 and lambda = 1.135 for 1998-1999 to 1999-2000) while in S. pulcherrima populations, lambda was very close to 1 (SP-1: lambda = 0.991 for 1997-1998 to 1998-1999 and lambda = 0.969 for 1998-1999 to 1999-2000; SP-2: lambda = 1.000 for 1997-1998 to 1998-1999 and lambda = 1.101 for 1998-1999 to 1999-2000). In the S. baetica population, values varied between lambda = 0.971 for 1997-1998 to 1998-1999 and lambda = 1.345 for 1998-1999 to 1999-2000. In the three species, an elasticity analysis of matrix projection models revealed that the elements with the greatest effect on population growth were those of reproductive plants remaining within the same reproductive class. In addition, in S. enneaphylla, seedlings had important weight for population growth. The fact that the reproductive stages are the most critical to population growth should be taken into account where protective or conservation action is required.