Regresar

Temporal changes in local spatial structure of late-successional species: Establishment of an Andean caulescent rosette plant

Abstract:

1. We analyse successional changes in local spatial structure of populations of a dominant late-successional species (Espeletia schultzii) in the high tropical Andes. 2. Spatial maps of plants of E. schultzii and important features of their environment were recorded at early (year 3) and middle (year 8) stages of succession after agricultural disturbance, and in non-cultivated páramo. 3. Spatial covariance functions were calculated from the maps to provide information on the changing 'plant-eye's view' of seedlings and adults during succession, and on the coupling of spatial structure to dynamics of successional communities. 4. Seedlings of E. schultzii appeared at high densities shortly after agricultural disturbance ceased. Spatial aggregation, which among seedlings was strongest in later stages of succession, was absent among adults, suggesting greater mortality within aggregations of conspecifics plays a part in regulating population dynamics. 5. Early in succession, seedlings of E. schultzii were slightly segregated from the dominant early successional species, Rumex acetosella. By year 8 of succession, R. acetosella was strongly segregated from adults of E. schultzii, but not from seedlings. This suggests that competitive exclusion caused by asymmetric competition may contribute to decline in early successional species. 6. Spatial sorting in relation to abiotic factors was most evident in the mature páramo, with E. schultzii adults occurring on steeper slopes and on less stony ground. E. schultzii adults here were also segregated from Hypericum laricifolium, the other dominant species. 7. The coupling of local spatial structure to community dynamics may have profound effects on succession. In particular, the development of interspecific segregation could contribute to the continued coexistence of early and late successional species throughout succession.