Marcelino J. del Arco Aguilar

Bioclimatic and vegetation mapping of a topographically complex oceanic island applying different interpolation techniques

Different spatial interpolation techniques have been applied to construct objective bioclimatic maps of La Palma, Canary Islands. Interpolation of climatic data on this topographically complex island with strong elevation and climatic gradients represents a challenge. Furthermore, meteorological stations are not evenly distributed over the island, with few stations at high elevations. We carried out spatial interpolations of the compensated thermicity index (Itc) and the annual ombrothermic Index (Io), in order to obtain appropriate bioclimatic maps by using automatic interpolation procedures, and to establish their relation to potential vegetation units for constructing a climatophilous potential natural vegetation map (CPNV). For this purpose, we used five interpolation techniques implemented in a GIS: inverse distance weighting (IDW), ordinary kriging (OK), ordinary cokriging (OCK), multiple linear regression (MLR) and MLR followed by ordinary kriging of the regression residuals. Two topographic variables (elevation and aspect), derived from a high-resolution digital elevation model (DEM), were included in OCK and MLR. The accuracy of the interpolation techniques was examined by the results of the error statistics of test data derived from comparison of the predicted and measured values. Best results for both bioclimatic indices were obtained with the MLR method with interpolation of the residuals showing the highest R2 of the regression between observed and predicted values and lowest values of root mean square errors. MLR with correction of interpolated residuals is an attractive interpolation method for bioclimatic mapping on this oceanic island since it permits one to fully account for easily available geographic information but also takes into account local variation of climatic data.

Taxonomy and chemotaxonomy of some species of celastraceae

Abstract β-Amyrin, iguesterin, celastrol, pristimerin, tingenone, salaspermic acid, 3β,29-dihydroxy-glutin-5-ene and myricadiol are found in the root extract of Maytenus umbellata . Its chemical composition is thus similar to that of the other Macaronesian endemic, Maytenus canariensis Loes and also to the East African Catha edulis Forsk.

New sesquiterpenes fromMaytenus species (Celastraceae). Taxonomic and chemotaxonomic considerations concerning chileanMaytenus

Three new dihydro-β-agarofuran sesquiterpenes from two species ofMaytenus were isolated and their structures were elucidated by means of1H and13C NMR studies. The differences and similarities noted in the chemical content of the dihydro-β-agarofuran sesquiterpenes from the fourMaytenus species from Chile are in line with the taxonomic characterization of these species; their geographical distribution is also given.

CONTRIBUCION AL ESTUDIO FITOSOCIOLOGICO DEL PINAR GRANCANARIO (ISLAS CANARIAS)

Sc lleva a cabo una caracterizacion bioclimatica, floristica y fitosociologica de Pinetum canariensis , el pinar autoctono dle la Isla de Gran Canaria, y se describe la nueva subasociacion juniperetosum canariensis . Se hacen diversas consideraciones sobre las comunidades arbustivas de sustitucion y se describe la nueva asociacion Euphorbio regis-jubae-Cistetum monspeliensis .

Changes in the Natural Landscape Through Human Influence

The arrival of the human being in the islands caused a gradual alteration of the plant cover. Initially, changes started slowly, because the aboriginal population was relatively scarce and lacked metal tools for massive felling. But changes in the vegetation accelerated after the Castilian conquest, which brought a major population increase, better tools, a greater demand for land and wood, and new large livestock farm animals with their intensive plant consumption.

Other Floristic Considerations

The Canarian non-vascular flora (s.l.) is estimated at 5508 species of which 163 are considered endemic. It includes algae, fungi, lichens and bryophytes, highly diverse organisms belonging to five kingdoms, Fungi, Bacteria, Protozoa, Chromista and Plantae, living in terrestrial and marine environments. They notably contribute to the biodiversity of the islands as shown in Table 5.1, which includes data from several recent catalogs.

Conservation Status of the Canarian Flora and Vegetation

After the conquest, the increasing disturbance of the island ecosystems, and their fragility, forced the authorities to implement conservation measures to protect them. Thus, since the sixteenth century, provisions were enacted and sometimes implemented to control the destruction of forests and water sources. In later centuries, reforestation was regulated in the most sensitive areas, to avoid damage that could have a negative impact on the island’s economy and development. However, it would not be until the mid-twentieth century when conservation was taken seriously from an ecological point of view.

The name "Salicornietum perennis" ("sensu lato") and global nomenclatural issues

The name Zygophyllo fontanesii-Sarcocornietum perennis is rejected as it is invalid and the new name Halimiono portulacoidis-Salicornietum perennis is proposed with two subassociations: typicum and limonietosum canariensis. The name Salicornietum perennis for Cuban communities is corrected to Salicornietum ambiguae .

14. About Aeonio-Euphorbion canariensis Sundíng 1972, correct alliance name against Kleinio-Euphorbion canariense Rivas Goday & Esteve 1965

About Aeonio-Euphorbion canariensis Sunding 1972, correct alliance name against Kleinio-Euphorbion canariense Rivas Goday & Esteve 1965