| 1. |
- Holmgren, Karin, et al.
(author)
-
The vulnerable continent (PLATINA) : Historical perspectives on Africa´s climate, environment and societies
- 2009
-
In: Meeting global challenges in research cooperation. - Uppsala : Uppsala University. - 9789197574198 ; , s. 585-596
-
Conference paper (peer-reviewed)abstract
- Our research, based on studies of different climate archives from Tanzania, Mozambique and South Africa, contributes information on changes in climate and vegetation over the past 24000 years. This time perspective, reaching beyond the information available from instrumental records is needed for a better understanding of regional global climate dynamics and issues surrounding environmental change, throughout Africa, and is a prerequisite for increasing climate forecasting capabilities for the region. We argue that African people have vast experience from living in a variable climate and research on past interactions between climate and societies demonstrate the significance of lessons learnt for present situations. Our findings, underline the complex interactions between climate/environment and societies that may lead to different developments in time and space. Considering the so called vulnerable continent, extended investigations of how African communities cope with and adapt to climatically driven changes is needed to increase the capability to realise the potential as well as the limitations, of modern African communities to adapt to future climate change.
|
|
| 2. |
- Marchant, Rob, et al.
(author)
-
Drivers and trajectories of land cover change in East Africa : Human and environmental interactions from 6000 years ago to present
- 2018
-
In: Earth-Science Reviews. - : Elsevier. - 0012-8252 .- 1872-6828. ; 178, s. 322-378
-
Journal article (peer-reviewed)abstract
- East African landscapes today are the result of the cumulative effects of climate and land-use change over millennial timescales. In this review, we compile archaeological and palaeoenvironmental data from East Africa to document land-cover change, and environmental, subsistence and land-use transitions, over the past 6000 years. Throughout East Africa there have been a series of relatively rapid and high-magnitude environmental shifts characterised by changing hydrological budgets during the mid- to late Holocene. For example, pronounced environmental shifts that manifested as a marked change in the rainfall amount or seasonality and subsequent hydrological budget throughout East Africa occurred around 4000, 800 and 300 radiocarbon years before present (yr BP). The past 6000 years have also seen numerous shifts in human interactions with East African ecologies. From the mid-Holocene, land use has both diversified and increased exponentially, this has been associated with the arrival of new subsistence systems, crops, migrants and technologies, all giving rise to a sequence of significant phases of land-cover change. The first large-scale human influences began to occur around 4000 yr BP, associated with the introduction of domesticated livestock and the expansion of pastoral communities. The first widespread and intensive forest clearances were associated with the arrival of iron-using early farming communities around 2500 yr BP, particularly in productive and easily-cleared mid-altitudinal areas. Extensive and pervasive land-cover change has been associated with population growth, immigration and movement of people. The expansion of trading routes between the interior and the coast, starting around 1300 years ago and intensifying in the eighteenth and nineteenth centuries CE, was one such process. These caravan routes possibly acted as conduits for spreading New World crops such as maize (Zea mays), tobacco (Nicotiana spp.) and tomatoes (Solanum lycopersicum), although the processes and timings of their introductions remains poorly documented. The introduction of southeast Asian domesticates, especially banana (Musa spp.), rice (Oryza spp.), taro (Colocasia esculenta), and chicken (Gallus gallus), via transoceanic biological transfers around and across the Indian Ocean, from at least around 1300 yr BP, and potentially significantly earlier, also had profound social and ecological consequences across parts of the region. Through an interdisciplinary synthesis of information and metadatasets, we explore the different drivers and directions of changes in land-cover, and the associated environmental histories and interactions with various cultures, technologies, and subsistence strategies through time and across space in East Africa. This review suggests topics for targeted future research that focus on areas and/or time periods where our understanding of the interactions between people, the environment and land-cover change are most contentious and/or poorly resolved. The review also offers a perspective on how knowledge of regional land-use change can be used to inform and provide perspectives on contemporary issues such as climate and ecosystem change models, conservation strategies, and the achievement of nature-based solutions for development purposes.
|
|
| 3. |
|
|
| 4. |
- Ryner, Maria, et al.
(author)
-
Vegetation changes in Empakaai Crater, northern Tanzania, at 14,800–9300 cal yr BP
- 2006
-
In: Review of Palaeobotany and Palynology. - 0034-6667. ; 140, s. 163-174
-
Journal article (peer-reviewed)abstract
- Vegetation changes are documented from a well-dated pollen record from Lake Emakat, Empakaai Crater, northern Tanzania.This pollen record includes the time interval covering the Pleistocene/Holocene transition, analysed at a resolution intervalaveraging 200 yr. Around the crater lake, an Hagenia-forest development starting at 14,500 cal yr BP lasted until 13,000 cal yr BP.A change in vegetation, indicated by an increased proportion of Nuxia congesta in the forest and Artemisia in the afro alpinegrassland after 13,000 cal yr BP, corresponds in time to the Northern Hemisphere's Younger Dryas cooling. Grasses and sedgesincreased at ∼10,100 cal yr BP, indicating a significant increase in local pollen possibly attributed to lowered lake level, related todrier conditions. Although the Empakaai pollen record documents continuous forest conditions, from 14,500 to 10,100 cal yr BP,the variation in the proportion of forest components seem to respond to environmental changes at the millennium scale
|
|
| 5. |
- Öberg, Helena, et al.
(author)
-
Environmental variability in northern Tanzania from AD 1000 to 1800, as inferred from diatoms and pollen in Lake Duluti
- 2013
-
In: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 374, s. 230-241
-
Journal article (peer-reviewed)abstract
- Fossil pollen and diatoms have been analyzed in a sediment sequence from a topographically closed crater lake in northern Tanzania (Lake Duluti), with the aim to reconstruct past changes in lake level and vegetation dynamics. The results provide a new paleoenvironmental record from equatorial Africa covering the period c. AD 1000 to AD 1800. Overall, the pollen and diatom records generate comparable stories of dry and wet periods. Dry conditions are inferred at c. AD 1040-1470, c. AD 1510-1640 and C. AD 1650-1670 with the lowest lake levels at c. AD 1260-1290 and AD 1600-1640. Wetter conditions occurred c. AD 1640-1650 and c. AD 1670-1790. The chronology is based on combined analyses of Pb-210 activity and AMS C-14 on bulk sediment, and a Bayesian model was applied to establish the age-depth relationship. The hydroclimatic record from Lake Duluti shows good correlation with several East African lakes in a centennial time perspective, although comparison of high frequency variability in the region is hampered by dating uncertainties.
|
|
| 6. |
- Öberg, Helena, 1974-, et al.
(author)
-
Environmental variability in northern Tanzania from c. AD 1000 to 1800, as inferred from diatoms and pollen in Lake Duluti
-
Other publication (other academic/artistic)abstract
- Fossil pollen and diatoms have been analysed in a sediment sequence from a topographically closed crater lake in northern Tanzania(Lake Duluti), with the aim to reconstruct past changes in lake level and vegetation dynamics. The results contribute with a new paleoenvironmental record from equatorial Africacovering the period c. AD 1000 to AD 1800. Overall, the pollen and diatom records generate comparative stories of dry and wet periods. Dry conditions are inferred at c. AD 1040–1470, c. AD 1510–1640 and c. AD 1650–1670 with the lowest lake levels at c. AD 1260–1290 and AD 1600–1640. Wetter conditions occurred c. AD 1640–1650 and c. AD 1670–1790. The chronology is based on combined analyses of 210Pb activity and AMS 14C on bulk sediment, and a Bayesian model was applied to establish the age-depth relationship. The hydroclimatic record fromLakeDuluti shows good correlation with several East African lakes although precise comparison is hampered by dating uncertainties.
|
|
