Land management and plant evolution: Biodiversity and conservation in anthropogenic landscapes
In the context of ecological theory, my lecture deals with the interaction of land management and species evolution. Any ecological theory is based on the knowledge of species, and the interactions of biodiversity (expressed as species richness) and ecology result in the conflicts of conservation and land-management.
I give an example from Germany, focusing (1) on species richness over time including extinction, and the role of forests, (2) on conservation and land-management, and (3) on invasive species.
Species richness has increased exponentially since the Neolithic. The increase is neither due to plant imports from agriculture, nor due to the discovery of North America, but mainly due to speciation of native species on managed land. A third of the present flora on managed land is apomyctic and hybrid. Forests, which are usually regarded as stronghold of natural species richness contain only about 10% of the flora. Extinction rate is very low. In forests we lost 1 species over the past 200 years. We maintained species not because of conservation, but due to proper management. The expected loss of species is largest on conservation land due in-proper wild-life management. The role of apomycts and hybrids needs recognition in ecological theory
Conservation is rather diffuse. There is (i) legal protection, (ii) the classification of Red Lists by IUCN, and (iii) the “responsibility” of nations to maintain certain species under the concept of Natura 2000 in Europe. Responsible for legal conservation is an administration, the Red List is produced by lay people, mainly NGO’s, “responsibility” is taken by an administration. The total number of plants presently tagged as endangered is about a third of the flora excluding apomycts, but the overlap is minimal. In forests, only 3 out of 178 forest species are protected, red-list-endangered or covered by “responsibility”. The number of endangered species is lower than the number of emerging species. At present, there is no theory on conservation including the role of management. Ecosystem functions may also act against theory. Net carbon flux of forests appears lower in species rich than in poor regions, due to land management.
Invasive species in forests are generally species that were present in the Tertiary. I suggest a new term, the Palaeo-Neophytes, to account for this, as exemplified by Pseudotsuga.
I propose that ecological theory has not taken land-management into account, and that the links between species evolution and conservation remain poorly understood.