WELCOME TO "LANDSCAPE ECOLOGY AND PEOPLE" - BOTANY 331

1. WELCOME TO "LANDSCAPE ECOLOGY AND PEOPLE" - BOTANY 331 • This course integrates landscape ecological processes with the impacts humans have on their environment. • It examines environmental management from a biological perspective and recognises that in order to manage one's environment and resources, one must manage and educate people. • Many of Africa's environmental problems are caused by poverty and a lack of environmental education, while in the developed world human greed is as a key factor. • As a currency to managing our environment we use "Biodiversity“ - and this concepts figures predominantly throughout the course. • Practical aspects of this course include introduction to field data collection and analysis, GIS, EIAs and SA Environmental Legislation.

2. BIODIVERSITY • The richest environments in terms of species appear to be: • Tropical rainforests – plants and insects • Coral reefs - spread over phyla and classes • Large tropical lakes - fish • Deep sea? • Tropical dry habitats also species rich (shrublands, • grasslands and some deserts) – plants and fauna • Mediterranean shrublands (Cape, southern California and • southwestern Australia) – plants and insects • Heathlands – plants and invertebrates

3. PATTERNS OF BIODIVERSITY - derived from the work by taxonomists. The current state of knowledge is imperfect (e.g. 80% of beetles collected recently in Panama are new spp., yet Panama is a “relatively well known” tropical country). Species diversity increases towards the tropics (France and Venezuela: 113 & 305 mammal spp. respectively). Generally there is an approx. correspondence in the distribution of spp. richness in different groups of organisms. However, each group or taxa may reach its greatest species richness in a different part of the world. In Africa, butterflies are most diverse in West Africa (N of the equator) & plants are most diverse in West Africa & CFR, while birds, primates and other mammals are most diverse in Central and East Africa.

4. Patterns of diversity in terrestrial spp. are paralleled by patterns in marine spp. • On the Great Barrier Reef 50 genera of reef-building corals occur at the northern end - only 10 at the southern. • In the sea squirts (tunicates) there are only 103 spp. in Arctic waters and over 600 spp. in tropical waters. • Patterns of spp. richness are also effected by local variation in topography, climate and other abiotic factors. • In terrestrial communities spp. richness tends to decrease with increasing elevation, decreasing solar radiation and decreasing precipitation. • Spp. richness may be greater where there is complex topography that allows genetic isolation, local adaptation, and ensuing speciation. • Historical factors are important with geologically older systems having more spp. than younger systems.

6. WHY ARE TROPICAL REGIONS SO RICH? More tropical areas have not been as influenced by glaciation periods than temperate areas, and consequently tropical areas have more stable climates. In temperate areas (e.g. Pine forest communities), species have had to keep shifting northwards or southwards depending on the retreat or advance of the glaciers. Tropical areas have had more time to evolve different species, and to more effectively partition resources. Consequently the habitat requirements and reproductive biology of many tropical spp. are highly specialised.

7. HOW MANY SPECIES CO-EXIST WORLDWIDE? The first problem is that some groups of organisms are well known and have been reasonably thoroughly collected, whereas others are relatively unknown. For example mammals species have been extensively collected (although only a couple of years ago a new species was recorded from Vietnam). Similarly most of the world’s bird species have been collected, and while there is a distinct probability that a new species could be discovered not many new species are likely to be found. We also find that Northern Temperate areas have much more of their faunas and floras described, this is because so many more people have been researching these areas - and also there are fewer species.

8. Tropical areas are known to have higher biodiversity that temperate. While new spp. have been discovered by sampling in remote areas others have been discovered by luck - events such the discovery of the Coelacanth “fossil fish” Latimeria chalumnae in 1938 of the East Coast of Africa - the only representative of a group of fishes thought to have been extinct since the Devonian times (400MY BP). New spp. have also been “discovered” through molecular systematics. Groups of animals such insects, spiders, mites, nematodes and fungi are generally poorly collected, but are being increasingly described at a rate of 1-2% per year, and huge numbers of spp. are still to discovered. Currently about 1.5 million species are know, but this figure grossly under estimates the real number of spp.

9. HOTSPOT ANALYSIS Myers defined hotspots as areas characterised by high species richness & high concentrations of endemic species, which are experiencing high rates of habitat modification or loss. Initially Myers identified 10 hotspots, all of which were in tropical rainforest. He then extended his hotspot analysis; to include additional Rain Forests and four Mediterranean-climate regions including the Cape Floristic Region (CFR). Today there are a total of 25 hotspots which have 50 000 spp. The CFR has over 6 000 endemic species and emerged as the "hottest" of the world's hotspots, with the Succulent Karoo a close second, and the Pondoland-Tongaland hotspot third SA hotspot.

10. The Flora of South African (FSA) extends south of the Kunene and Limpopo Rivers. It comprises 21 137 spp. of vascular plants, 80% of which are endemic. Plant endemism is not distributed evenly across South Africa. Spp. richness is higher in SA than in 8 of the 12 "Megadiversity countries"; namely Australia, Ecuador, India, Indonesia, Madagascar, Malaysia, Peru and Zaire. In contrast to the above countries the SA flora has mainly warm-temperate and semi-arid spp., the country has a mean annual rainfall of some 400 mm (and the amount and seasonality of rainfall does varies considerably over SA).

11. TABLE. Listing the vascular plant species density in southern Africa to similar sized regions of the world

12. Another difference between FSA and other floristically rich areas is the lack of rainforest spp. (forest cover less than 1% of the FSA). • The FSA's rich biodiversity is attributable to a transitional position with respect to subtropical summer rainfall and temperate/winter rainfall regimes, in combination with complex topography, and heterogeneity of geology and soils. These circumstances produce many steep ecological gradients along which species can partition themselves. • FSA has been divided into ; • 5 phytochoria • 7 biomes • 70 major vegetation categories or veld types (Acocks, 1953) • 68 vegetation types identified by Low & Rebelo (1996) • Historical processes have also contributed to the regions biodiversity.