Pablo García-Murillo

CHANGES IN THE WETLANDS OF ANDALUSIA (DOÑANA NATURAL PARK, SW SPAIN) AT THE END OF THE LITTLE ICE AGE

The Little Ice Age is a climatic period still insufficiently known. This ignorance is more marked in the case of Andalusia (southern Spain), where only recent works throw any light on the topic. Our studies, primarily from the perspective of botany and changes in the plant landscape, reveal the effects that this period had in these latitudes, and in particular on the Doñana Natural Park (SW Spain). This work shows an aridization in climatic conditions coinciding with the end of the Little Ice Age. The results corroborate the most recent theses on this period in Spain. Furthermore, the effects on the marsh areas studied lead us to conclude that the interpretation of the Little Ice Age in these southern latitudes should be different to that normally given for more northerly latitudes – much better known and more studied than the Mediterranean regions.

Can place names be used as indicators of landscape changes? Application to the Doñana Natural Park (Spain)

This work broaches the possibility of using place names as indicators of original landscapes that have been much transformed. The reconstruction of landscape elements from place names is commonly disputed because such daring notion is impossible to demonstrate. The present case avoids this by making a preliminary study of changes in the landscape using conventional methods. With the knowledge gained from objective and reliable sources, the possibility is analyzed of whether place names are a reflection of landscape changes taking place over a considerable period of time (the last few centuries). It is concluded that, for the present case study, in natural areas with a high rate of change of land use (Doñana Natural Park), place names indicate not only changes in the landscape, but also how such changes are perceived. In the study area, this is especially clear regarding the fens.

Chromosome numbers and a new model for karyotype evolution in Ruppia L. (Ruppiaceae)

Talavera, S., Garcia-Murillo, P. and Herrera, J., 1993. Chromosome numbers and a new model for karyotype evolution in Ruppia L. ( Ruppiaceae ). Aquat. Bot., 45:1 - 13. Populations of three species in the genus Ruppia that inhabit the western part of the Mediterranean region were studied caryologically. All three species present bimodal karyotypes. Ruppia drepanensis Tineo ex guss. (2n = 20) has a karyotype asymmetry of the 2C type. Ruppia cirrhosa (Petagna) Grande and Ruppia maritima L. (both with 2n=40) present a 2B asymmetry. Observations of meiosis of microspore mother cells revealed that R. drepanensis forms ten bivalents at diakinesis and Metaphase I. The other two species exhibit 20 bivalents. The long arm of subtelocentric, large chromosomes in all three species shows no sign of chiasmata at meiosis.

Changes in the Erica ciliaris Loefl. ex L. peat bogs of southwestern Europe from the 17th to the 20th centuries AD

This paper analyses a reconstruction of changes from the 17th to the 20th centuries in peat bogs with Erica ciliaris Loefl. ex L. heathlands in southwestern Europe. The reconstruction is performed by means of a multidisciplinary method based on photointerpretation, the examination of historical sources (documentation and maps), and an analysis of microtopography. Historical sources and aerial photos from 1956 and 1987 have also been used to reconstruct the impacts of anthropic activity. In the study area, Doñana Natural Park (SW Iberian Peninsula), peat bogs currently occupy slightly more than 8% of the area that they covered at the beginning of the 17th century. A parallel analysis of anthropic activity in the area over the last four centuries reveals the key role of humans in the disappearance of these peat bogs. This drastic reduction of peat bog area during the 20th century is due to a lowering of the water-table as a result of the impacts of anthropic activity, primarily the establishment of monocultures of Eucalyptus spp. and Pinus pinea. An earlier lowering of the water-table, before these plantations, is attributable to a process of aridisation associated with post-‘Little Ice Age’ warming. Therefore, the impacts associated with climatic trends are synergistically superimposed on those derived from the intense anthropic activity that occurred during the second half of the 20th century. This synergy resulted in a reduction of the surface occupied by the studied peat bogs and their associated E. ciliaris heathlands by 91.1% in SW Europe.

Aquatic plant distribution is driven by physical and chemical variables and hydroperiod in a mediterranean temporary pond network

The aim of this study was to assess aquatic plant distribution patterns in a Mediterranean temporary pond network (Doñana National Park, SW Spain). We analyzed differences in species composition employing multivariate ordination techniques; we specifically examined the importance of hydroperiod and physical and chemical variables in the five geomorphological areas across which the pond network is spread. The ponds significantly segregated along a north–south gradient, matching the segregation pattern of the aquatic plant assemblages. Ponds in the three northernmost areas showed higher levels of species richness than ponds in the two southernmost areas. In the north, ponds were present at higher densities, spanned a broader hydroperiod range, and had lower conductivity levels; these features were associated with the presence of wet-meadow species and larger numbers of submerged and emergent species. In the south, alkaline waters were mainly associated with different charophyte species, and the predominance of long-hydroperiod ponds helped in increasing the number of floating species. Managed ponds, which had been artificially deepened, contributed to increase pond heterogeneity and hydroperiod breadth across the entire network. At present, such ponds are key to the preservation of Doñana’s rich and unique aquatic plant community.

A new delimitation of the Afro-Eurasian plant genus Althenia to include its Australasian relative, Lepilaena (Potamogetonaceae) – Evidence from DNA and morphological data

Althenia (Potamogetonaceae) is an aquatic plant genus disjunctly distributed in the southern- (South Africas Cape Floristic Region: CFR) and northern- (Mediterranean Eurasia) hemispheres. This genus and its Australasian relative, Lepilaena, share similar floral characters yet have been treated as different genera or sections of Althenia sensu lato (s.l.) due to the isolated geographic distribution as well as the differences in sex expression, stamen construction, and stigma morphology. The diagnostic characters, however, need reevaluation over the boundaries between the entities. Here we tested the taxonomic delimitation between the entities, assessed synapomorphies for evolutionary lineages, and inferred biogeographic history in a phylogenetic framework. Our results indicated that Lepilaena was resolved as non-monophyletic in both plastid DNA and nuclear PhyC trees and Althenia was nested within it. As Althenia has nomenclatural priority, we propose a new delimitation to recognize Althenia s.l., which can be diagnosed by the female flowers with 3-segmented perianths and male flowers with perianths. The previously used diagnostic characters are either autapomorphies or synapomorphies for small lineages within Althenia s.l., and evolutionary transitions to sessile female flowers and narrow leaves characterize larger clades. Biogeographic analyses suggested a Miocene origin of Althenia s.l. in Australasia and indicated at least one inter- and one intra-specific inter-continental dispersal events among Australasia, Mediterranean Eurasia, and CFR need to be hypothesized to explain the current distribution patterns.

Effect of the filling season on aquatic plants in Mediterranean temporary ponds

Aims Pond environmental conditions may differ among years with regards to the season in which ponds begin to fill. We experimentally evaluated how seedling emergence, plant growth and phenology differed among years in which filling occurred in winter, autumn or spring. Methods We collected sediments from a natural temporary pond and located them in aquariums. They were placed in a climatic chamber that simulated annual variation in field environmental temperatures and light conditions. Aquariums were assigned to one of three treatments, which differed in the date on which they were filled with water (autumn, winter and spring). We counted the number of seedlings of different species emerged and recorded data about the presence of flowers, seeds or spores every week. The experiment was finished in June, when we harvested the plants and estimated their biomass. Important Findings In most species, seedling emergences were primarily related to time after filling, and thus synchronized their life cycles with the unpredictably timed wet phase of the ponds. Autumn filling resulted in the highest numbers of seeds/spores. However, winter filling promoted plant growth the most. In the spring filling treatment, more terrestrial plant seedlings emerged and fewer seeds/spores were produced. When ponds are flooded earlier, plants may produce a higher number of propagules. However, in years when inundation is delayed to spring and hydroperiods are short, seedling emergence deplete the seed bank and there is little to no seed production, while terrestrial monocots are able to colonize pond basin.

Nymphaea mexicana Zuccarini in the Iberian Peninsula

Abstract Nymphaea mexicana Zuccarini, a species from southern USA and Mexico, is reported for the first time from the Iberian Peninsula. A brief description of the site and taxonomical characteristics are given.