| 1. |
- Mpondo, Faith T., et al.
(författare)
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Insect visitation and pollination networks across traditional rangeland management categories in a Northern Tanzanian rangeland
- 2023
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Ingår i: Global Ecology and Conservation. - 2351-9894. ; 46
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Tidskriftsartikel (refereegranskat)abstract
- The structure of pollination networks is critical to ecosystem stability and functioning. We investigated pollinator-plant interactions to understand the foraging preference and develop pollination networks in a semi-arid rangeland of different grazing management categories in Tanzania. Along three line transects, each measuring 100 m, in each of the four grazing management categories (private and communal enclosures, wet and dry season grazing areas), we laid out three quadrats measuring 5 m x 5 m (25 m2,) located 30 m apart. We recorded insects visiting flowering plants for two consecutive days in each quadrat every week at each site from April to May, in 2019 and 2020. Aspilia mossambicensis received the most significant proportion of insect visitors (28%), followed by Justicia debile (21%). The mean protein concentration in sampled pollen varied significantly between plant species (& chi;2 = 25.9, P = 0.001), with Solanum incanum containing the highest concentration (299.3 & PLUSMN; 0.68) g/100 g. We did not notice any correlation between honey bee visitation and protein concentration in pollen (r = -0.471, P = 0.239) nor with fatty acids concentration (r = 0.253, P = 0.546). When comparing pollinator-plant network properties including connectance, nestedness, robustness, number of links, modularity, network diversity and linkage density across rangeland management, we found that the private enclosure contained significantly larger networks than the communal enclosure, the dry and the wet season grazing sites. We conclude that particularly private enclosures are vital to promote pollination networks in our studied rangeland system as they include important pollinator forage plants.
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| 2. |
- Abihudi, Siri A., et al.
(författare)
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Conservation status revision and communities' perceptions of 22 Aloe species in Tanzania
- 2021
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Ingår i: Plant Ecology and Evolution. - : Agentschap Plantentuin Meise. - 2032-3913 .- 2032-3921. ; 154:3, s. 391-404
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims – Many Aloe species are globally threatened due to overharvesting for trade and habitat destruction. CITES regulates their international trade. In Tanzania, 50% of all existing Aloe species had previously been assessed, though some of these assessments were Data Deficient. For those with sufficient data, an update is required as the rate of decline has rapidly increased over the last years.Material and methods – We estimated Area of Occupancy (AOO), Extent of Occurrence (EOO), and number of locations for 22 Tanzanian Aloe species using the Geospatial Conservation Assessment software (GeoCAT). We assessed the reasons leading to their decline based on direct field observations and community perceptions.Key results – We revised the conservation status of 22 Aloe species; two were assessed as Critically Endangered, ten as Endangered, five as Vulnerable, and five as Least Concern. We re-discovered the Critically Endangered Aloe boscawenii, which had not been seen in Tanzania for more than six decades. We propose to downgrade the endemic Aloe dorotheae, Aloe leptosiphon, and Aloe flexilifolia from Critically Endangered to a lower threat level. The community perception on Aloe species availability did not accurately reflect their categorisation based on the IUCN criteria B. We identified agricultural activities and climate change effects as the two main threats to Tanzanian Aloe species.Conclusion – We conclude that overall numbers are declining for 22 Aloe species in Tanzania, mainly due to human activities. We recommend the implementation of laws and policies to protect their natural habitats.
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| 3. |
- Cosme, Maximilien, et al.
(författare)
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Qualitative Modeling for Bridging Expert-Knowledge and Social-Ecological Dynamics of an East African Savanna
- 2022
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Ingår i: Land. - : MDPI AG. - 2073-445X. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Sub-Saharan social-ecological systems are undergoing changes in environmental conditions, including modifications in rainfall pattern and biodiversity loss. Consequences of such changes depend on complex causal chains which call for integrated management strategies whose efficiency could benefit from ecosystem dynamic modeling. However, ecosystem models often require lots of quantitative information for estimating parameters, which is often unavailable. Alternatively, qualitative modeling frameworks have proved useful for explaining ecosystem responses to perturbations, while only requiring qualitative information about social-ecological interactions and events and providing more general predictions due to their validity for wide ranges of parameter values. In this paper, we propose the Ecological Discrete-Event Network (EDEN), an innovative qualitative dynamic modeling framework based on if-then rules generating non-deterministic dynamics. Based on expert knowledge, observations, and literature, we use EDEN to assess the effect of permanent changes in surface water and herbivores diversity on vegetation and socio-economic transitions in an East African savanna. Results show that water availability drives changes in vegetation and socio-economic transitions, while herbivore functional groups have highly contrasted effects depending on the group. This first use of EDEN in a savanna context is promising for bridging expert knowledge and ecosystem modeling.
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| 4. |
- Felix, Nancy, et al.
(författare)
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Retaliatory killing negatively affects African lion (Panthera leo) male coalitions in the Tarangire-Manyara Ecosystem, Tanzania
- 2022
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:8
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Tidskriftsartikel (refereegranskat)abstract
- In landscapes where people and lions coexist, conflicts are common due to livestock predation and threats to human safety. Retaliatory lion killing by humans is often a consequence and is one of the leading causes of lion population declines across Africa. We assessed the effects of retaliatory lion killing on male lion coalitions in the Tarangire-Manyara Ecosystem (TME) using a long-term dataset of lion monitoring for ten lion prides, spanning over a fourteen year-period from 2004-2018. We also interviewed 214 respondents about their attitudes and awareness of the effects of retaliatory killing on lions. We found that male lion coalitions were larger and lasted for a longer tenure period in locations with low risk of retaliatory killing, as well as far away from active hunting blocks. Further, young people (18-35 years old) had a more positive attitude towards lion existence and conservation compared to older age classes. Surprisingly, people with primary or secondary level of education were more likely to having lions killed if they attack livestock compared to people with no formal education, although the former supported lion presence for tourism in protected areas. We conclude that retaliatory killing has a large effect on long-term lion coalition dynamics and, thus, survival. Community awareness on retaliation effect varies widely, and we recommend implementing better education and policy strategies at TME to protect the declining carnivore populations.
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| 5. |
- Levi, Matana, et al.
(författare)
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Forage selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) at multiple spatial scales
- 2022
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Ingår i: Journal of Mammalogy. - : Oxford University Press (OUP). - 0022-2372 .- 1545-1542. ; 103:3, s. 737-744
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Tidskriftsartikel (refereegranskat)abstract
- Management of rangelands requires knowledge of forage species that are preferred or avoided by wildlife and livestock. A recent expansion of woody vegetation into previously open grasslands in African savanna ecosystems negatively impacts many mammalian grazers. Nevertheless, the ecological role of bush encroacher plant species as food may present a benefit for browsing species. We quantified diet selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) through foraging observations and vegetation sampling in the Tarangire Ecosystem of Tanzania, which includes large areas of a native shrub that livestock managers have classified as an encroacher species (Dichrostachys cinerea). We compared woody plant species used by giraffes for foraging with availability at two different spatial scales during the wet and dry seasons. Giraffes selected some woody plants such as Vachellia species while significantly avoiding others, both at the local and landscape scales. Giraffes preferred foraging on D. cinerea at both spatial scales and in both the wet and dry seasons. Management that has focused on benefiting grazing livestock by removal of encroaching species (e.g., D. cinerea) may have unintended consequences for wildlife, especially for browsing species like giraffes that feed extensively on the expanding bush species.
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| 6. |
- Leweri, Cecilia M., et al.
(författare)
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Spatial and seasonal group size variation of wild mammalian herbivores in multiple use landscapes of the Ngorongoro Conservation Area, Tanzania
- 2022
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:4
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Tidskriftsartikel (refereegranskat)abstract
- Group sizes of wild herbivores can be indicators of ecosystem health and proxies for individual and population fitness, particularly in areas where human activities have become increasingly common. We recorded 176 single- and multi-species groups of wild herbivores in human-dominated landscapes of the Ngorongoro Conservation Area (NCA) during dry and wet seasons. We analyzed how wild herbivore group sizes were affected by: (1) season, (2) distance to fully protected area (NCA crater) and to streams, (3) distance to human settlements, and (4) numbers of livestock. Group sizes were generally larger during the wet season than during the dry season and varied seasonally with distance to NCA crater, streams, and human settlements. During the wet season, larger groups were observed further away from the NCA crater whereas the opposite pattern was apparent during the dry season. Average wild herbivore group sizes increased by about three-fold with increasing distance from the streams during the dry season but were invariant to streams during the wet season. Furthermore, during the dry season, group sizes were larger close to settlements but varied little with distance to settlements during the wet season. While livestock presence did not directly affect wild herbivore group size, distance to settlements, streams and distance to the Ngorongoro crater in interaction with rainfall seasonality did. We conclude that the NCA crater functions as a key resource area for wild herbivores such as wildebeest (Connochaetes taurinus) and zebra (Equus quagga burchelli) during the dry season, highlighting the need for its full protection status in this Man and Biosphere reserve.
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| 7. |
- Mbundi, Mecklina M., et al.
(författare)
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Comparison of the effects of a broad-spectrum herbicide and a bio-herbicide on insect flower visitation in the Serengeti ecosystem, Tanzania
- 2021
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Ingår i: Journal for Nature Conservation. - : Elsevier BV. - 1617-1381 .- 1618-1093. ; 64
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Tidskriftsartikel (refereegranskat)abstract
- The functional role of insect visitors on flowering plants is crucial to both natural and agricultural ecosystems. While, few studies have addressed the impact of invasive plant species on insect visitors, even less is known about how management practices against invasive plants may affect plant-pollinator interactions. We assessed how natural versus chemical-based management against the invasive plant Gutenbergia cordifolia affected insect visitors in Mwiba area, Tanzania. We compared the number of insect visitors, diversity and richness, the number of inflorescences visited, inflorescences abundance and flower diversity across treatments of Desmodium uncinatum crude leaves extract (DUL), the chemical glyphosate (GLY), and none /control (CON). We found that more than half (55%) of the insect visitors observed were found visiting flowering plants in DUL plots, followed by CON with 26% and GLY plots with 19%. Further, DUL plots had almost twice as many inflorescences visited compared to CON and GLY plots. Inflorescence's abundance and flower diversity were significantly higher in DUL plots compared to CON and GLY plots. Our study revealed that DUL treatment did not disrupt insect flower visitation but rather attracted more insects. We conclude that using the natural plant extract treatment is highly preferable to the chemical management of invasive plants such as G. cordifolia, as the DUL treatment maintained and even enhanced flower diversity while suppressing G. cordifolia and fostering insect visitors.
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| 8. |
- Mero, Sarah A., et al.
(författare)
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Environmental factors and non-chemical methods to suppress growth of the invasive plant Gutenbergia cordifolia
- 2023
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Ingår i: Acta Oecologica. - 1146-609X .- 1873-6238. ; 119
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about preferred environmental conditions and non-chemical control of invasive Gutenbergia cordifolia. We assessed the effects of different A. annua crude extract concentrations, synthetic herbicide (glyphosate), fire regime and shade to G. cordifolia germination, shoot and root dry biomass, seedling height and leaf chlorophyll. High concentrations (75%) of A. annua crude extracts significantly reduced germination percentage of G. cordifolia by 25% (F2,4=77.2, p < 0.001), and suppressed shoot and root dry biomass (F2,4 = 80.3, p < 0.001; F2,4=46.104, p < 0.001, respectively) as well as seedling height and leaf chlorophyll (F2,4 = 12.02, p < 0.002; F2,4 = 15.9, p < 0.001), respectively. Medium temperature (60 °C) and long exposure time (5 min) significantly increased G. cordifolia germination percentage (F2,7 = 32.6, p < 0.001) while extreme temperatures (≥150 °C) at both (1 min) short and (5 min) long exposure time completely suppressed germination of G. cordifolia. Under high shade, while germination percentage was a third that of other treatments (F 2, 4 = 20.9, p = 0.008), mean germination took twice as long (F2, 4 = 17.9, p = 0.010) and shoot fresh biomass was reduced by half (F 2, 4 = 16.92, p = 0.004). Shoot and root dry biomass were reduced to more than a third under high shade, seedling height reduced to half but leaf chlorophyll content was not affected (F 2,4 = 6.3, p = 0.030; F 2,4 = 9.1, p = 0.020; F 2,4 = 18.3, p = 0.003; F 2,4 = 3.02, p = 0.120, respectively). We suggest using A. annua as a potential bio-herbicide and highlight considering fire and shade as suppressor tools to control G. cordifolia, but first include in-situ trials to assess their impacts to both native plants and animals.
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| 9. |
- Michler, Lena M., et al.
(författare)
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Moving Toward the Greener Side : Environmental Aspects Guiding Pastoral Mobility and Impacting Vegetation in the Dzungarian Gobi, Mongolia
- 2022
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Ingår i: Rangeland Ecology & Management. - : Elsevier BV. - 1550-7424 .- 1551-5028. ; 83, s. 149-160
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Tidskriftsartikel (refereegranskat)abstract
- Livestock grazing often intensifies around herder camps, which can lead to degradation, particularly in arid areas, where vegetation is scarce. In Mongolia, nomadic herders have covered long distances between camps and changed camps regularly for centuries. However, changing socioeconomics, rising livestock numbers, and climatic change have led to growing concerns over rangeland health. To understand travel mobility and livestock grazing patterns, we combined Global Positioning System tracking data of goats, remotely sensing pasture productivity, and ground-based vegetation characteristics in the Great Gobi B Strictly Protected Area, Mongolia. We assessed herder preferences for camp selection, followed 19 livestock herds over 20 months, determined use and nutrient contents of the most dominant plant communities, and estimated plant species richness, vegetation cover, and biomass within different grazing radii around camps. Biomass availability was key for herder decisions to move camps, but in winter, other factors like shelter from wind were more important. Camps were mainly located in Stipa spp. communities, agreeing with herder preferences for this highly nutritious species, and its dominance around camps. Herders changed their camp locations on average 9 times yearly, with a maximum distance of 70–123 km between summer and winter camps, and an average visitation period of 25–49 d per camp, depending on season. Small livestock spent > 13−17 h daily within a radius of 100 m from camp, and livestock use intensity decreased steeply with distance from camp but was remarkably similar around spring, autumn, and winter camps on the Gobi plains. However, we found little evidence for a corresponding gradient in plant species richness, biomass, and cover on the Gobi plains. The high mobility of local herders and the overriding impact of precipitation on pasture dynamics contribute to a sustainable vegetation offtake by livestock in the nonequilibrium rangelands of the Dzungarian Gobi.
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| 10. |
- Michler, Lena M., et al.
(författare)
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To move or not to move—factors influencing small-scale herder and livestock movements in the Dzungarian Gobi, Mongolia
- 2023
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Ingår i: Regional Environmental Change. - 1436-3798 .- 1436-378X. ; 23:4
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Tidskriftsartikel (refereegranskat)abstract
- In Mongolia, where nomadic pastoralism is still practiced by around one-third of the population, increasing livestock numbers, socio-economic constraints and climate change raise concerns over rangeland health. Little empirical evidence explains what triggers camp moves of pastoralists in the Dzungarian Gobi in Mongolia, which factors influence grazing mobility around camps, and how altitudinal migration benefits small livestock. We combined GPS tracking data of 19 small livestock herds monitored from September 2018 to April 2020 with remotely sensed climate and environmental data. We used general linear-mixed models to analyse variables influencing camp use duration and daily mobility patterns. To understand the importance of the altitudinal migration, we compared climatic conditions along the elevation gradient and looked at seasonal body weight changes of small livestock. We found that available plant biomass and season best explained camp use duration. Daily walking distance and maximum distance from camp increased with camp use duration. Pasture time increased with increasing biomass and rising temperatures. We conclude that herders in the Dzungarian Gobi have optimized pasture use by reacting to changes in biomass availability at landscape and local scale, and by embracing altitudinal migration. Flexibility in grazing mobility seems to have enabled local herder communities to practise sustainable pasture use. Maintaining this mobility will most likely be the best strategy to deal with environmental change under the current climate change scenarios.
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