Freshwater plants play a pivotal role in the health and functioning of freshwater ecosystems, and they also offer a variety of benefits to humans. Despite their importance, there is a significant gap in our understanding of the macroecology of freshwater plants in tropical regions, where biodiversity is typically high, and ecosystems face substantial pressures from human activities. To bridge this knowledge gap, we conducted extensive field surveys and applied statistical methods to understand the patterns of distribution, density, and diversity of freshwater plants and their relationship with abiotic components in four freshwater lakes in Kenya. We aimed to answer four key questions: (1) How many freshwater plant species occur in these lakes? (2) What proportion of these freshwater plant species are native and alien to Kenya? (3) What proportion of these species have a history of being invasive somewhere in the world, including in Kenya? (4) Which water and sediment characteristics are significantly associated with the presence, density, and diversity of freshwater plants in the lakes? We inventoried a total of 163 freshwater plant species, of which 114 were native to Kenya and 49 were alien. Online database searches revealed that 114 species had a history of invasion globally, with 22 species already invasive in Kenya. Our statistical analysis showed that the presence and density of plant species were positively correlated with pH and turbidity, but negatively correlated with soluble reactive phosphorus in both water and sediments, ammonia-nitrogen in sediments, and nitrate-nitrogen in water. Shannon-Wiener diversity of the plant species was positively correlated with ammonia-nitrogen in water and nitrate-nitrogen in sediments but negatively correlated with longitude and electrical conductivity of the water. Pielou’s evenness within the communities showed positive correlations with soluble reactive phosphorus in both water and sediments, ammonia-nitrogen in sediments, and nitrate-nitrogen in water but was negatively correlated with water turbidity and pH. The number of species with a history of invasion was positively correlated with longitude and electrical conductivity but negatively correlated with ammonia-nitrogen and nitrate-nitrogen in water. This extensive inventory not only enriches our understanding of the biodiversity within these freshwater plant communities but also highlights the potential risks posed by species with a history of being invasive. The findings regarding environmental variables linked to the presence, density, diversity, and invasive potential of these species underscore the complexity of freshwater ecosystems and the array of factors influencing the composition of freshwater plant communities.

It is increasingly being recognised that local people's knowledge can contribute to the ecological and socioeconomic goals of natural resource management programmes. Yet, few studies have examined local people's knowledge concerning freshwater macrophyte diversity. Consequently, the extent to which local people's knowledge can contribute to mitigating freshwater macrophyte degradation and supporting their management remains largely unknown. To contribute towards filling this knowledge gap, we investigated local people's knowledge, perceptions and management practices of freshwater macrophyte species. Data collection involved conducting face-to-face in-depth interviews and focus group discussions among local people who lived in areas adjacent to Lake Baringo, Nyanza Gulf of Lake Victoria and the Kenyan side of Lake Jipe. The sociodemographic characteristics of the respondents were summarised using descriptive statistics. Then, generalised linear mixed-effect models were used to test whether the respondent's sociodemographic characteristics were associated with their macrophyte species recognition skills, benefits and problems associated with macrophytes and management practices. Our respondents named a total of 35 macrophyte species, with each respondent naming an average of six species. Our results showed that respondents who were not involved in fishing and fish-related activities identified more macrophytes than those who participated in such activities. Additionally, individuals who frequently visited the lake named more macrophyte species compared to those who visited either daily or occasionally. While our respondents acknowledged various benefits and problems associated with macrophytes, there was a higher recognition rate for those that directly impacted humans. Regarding local management practices, it was observed that macrophytes were not conserved, with management efforts focusing solely on problematic species. Overall, macrophyte naming skills, knowledge on provisioning and supporting ecosystem services, direct adverse macrophyte impacts and management methods increased with age. We identified knowledge gaps regarding alien species and the indirect impacts of macrophytes. Addressing these gaps is crucial.

Rogelj J ORCID: https://orcid. org/0000-0003-2056-9061, Shindell D, Jiang K, Fifita S, Forster P, Ginzburg V, Handa C, Kheshgi H, et al.(2018). Chapter 2: Mitigation pathways compatible with 1.5 C in the context of sustainable development. In: Global Warming of 1.5 C an IPCC special report on the impacts of global warming of 1.5 C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change. Intergovernmental Panel on Climate Change.

Payment for Ecosystem Service (PES) is a market driven tool to motivate upstream land owners to practices land uses that enhance water quantity flows through compensation incentive packages supported by downstream beneficiaries and partners. PES is a voluntary engagement that involves negotiation by sellers and buyers of ecosystem products and services through independent intermediaries. The country is facing high deforestation and degradation rates within the key watersheds that threaten future supply of water for various socioeconomic activities. The PES concept has been around for the last two decades and many projects have been undertaken in the country hence the need to evaluate its adoption rates and subsequent outcomes to inform future direction of research and investments in PES schemes in the country. A study was initiated by Kenya Forestry Research Institute (KEFRI) and partners in 2016 to collect information on the experiences by several projects in the implementation of PES schemes. This was informed by the fact that information and data on use of PES in watershed management in Kenya is scanty and disjointed hence the needs for comprehensive study to update stakeholders on its status and experiences. Similarly, the country has to manage its watersheds in accordance with international standards and hence needs to tap into the most effective approaches and technologies available within its socioeconomic and ecological contexts. The study results indicate that the country has put in place some policy and legal framework to support PES piloting schemes. The cross sector study identified 15 projects on carbon sequestration, biodiversity conservation, watershed protection and a bundled combination of these services that have been implemented in the country. PES schemes promoted conservation friendly land uses and offered a wide range of incentives to communities and individuals who are custodians of the natural resources through negotiated engagements. The PES schemes faced several challenges related to high population, smallholder farms, inadequate policy and legal frameworks and governance issues that tended to increase implementation costs and hinder effective participation. The opportunities include a wide range of conservation land uses such as contour terraces, tree planting, grass strips along rivers and differed or controlled grazing in drylands. PES schemes in most cases have provided significant benefits and income opportunities to local communities including increased agricultural incomes, social assets, employment and biodiversity conservation. The experience from pilot PES schemes provides practical lessons that can inform the future design and implementation of PES models within the context of the local situations. The agencies that have interest in forestry and other environment services should continue to pursue the path of PES mechanisms to address environmental degradation and diminishing environmental resources. This is premised on the fact that ES services directly and indirectly support socioeconomic development especially at local levels. However, there is need for some policy and legislative reforms to mainstream PES principles sectoral plans and conservation projects and was enhance enforcement of existing legislation and Acts Keywords : payment for ecosystem services, experiences status, watersheds, income opportunities,

Contributing Authors: Katherine Calvin (USA), Oreane Edelenbosch (Netherlands), Johannes Emmerling (Germany/Italy), Sabine Fuss (Germany), Thomas Gasser (France/Austria), Nathan Gillet (Canada), Chenmin He (China), Edgar Hertwich (Austria/USA), Lena Höglund-Isaksson (Sweden/Austria), Daniel Huppmann (Austria), Gunnar Luderer (Germany), Anil Markandya (UK/Spain), David L. McCollum (USA/Austria), Richard Millar (UK), Malte Meinshausen (Germany/Australia), Alexander Popp (Germany), Joana Correia de Oliveira de Portugal Pereira (Portugal/UK), Pallav Purohit (India/Austria), Keywan Riahi (Austria), Aurélien Ribes (France), Harry Saunders (Canada/USA), Christina Schädel (Switzerland/USA), Chris Smith (UK), Pete Smith (UK), Evelina Trutnevyte (Lithuania/Switzerland), Yang Xiu (China), Kirsten Zickfeld (Germany/Canada), Wenji Zhou (China/Austria)

Contributing Authors: Katherine Calvin (USA), Joana Correia de Oliveira de Portugal Pereira (UK/Portugal), Oreane Edelenbosch (Netherlands/Italy), Johannes Emmerling (Italy/Germany), Sabine Fuss (Germany), Thomas Gasser (Austria/France), Nathan Gillett (Canada), Chenmin He (China), Edgar Hertwich (USA/Austria), Lena Höglund-Isaksson (Austria/Sweden), Daniel Huppmann (Austria), Gunnar Luderer (Germany), Anil Markandya (Spain/UK), David L. McCollum (USA/Austria), Malte Meinshausen (Australia/Germany), Richard Millar (UK), Alexander Popp (Germany), Pallav Purohit (Austria/India), Keywan Riahi (Austria), Aurélien Ribes (France), Harry Saunders (Canada/USA), Christina Schädel (USA/Switzerland), Chris Smith (UK), Pete Smith (UK), Evelina Trutnevyte (Switzerland/Lithuania), Yang Xiu (China), Wenji Zhou (Austria/China), Kirsten Zickfeld (Canada/Germany)

The status of biodiversity indicates that most ecosystems in East Africa are losing biodiversity at an alarming rate. This has compromised ecosystems functions and services with a resulting loss of livelihoods among local communities. One of the most impacted ecosystems by such trends are the small wetlands of East Africa. Land shortages and the degradation in most upland areas combined with a high production potential of wetlands is the single most important driver of the growing demand for wetlands resources. Clearing, drainage and cultivation of wetlands have created an ecological shift in species composition that promotes an opportunistic weed flora at the detriment of natural vegetation. We investigated the impact of the weed flora on the livelihoods of local communities within two floodplains, the Ewaso Narok swamp on the Laikipia plateau in Kenya, and the Pangani plain close to Malinda in the Tanga region of Tanzania. Land use gradients were classified as unused, abandoned (fallows) and cultivated areas (croplands). Weed species presence and cover were recorded in 117 plots measuring 100 m each. Interviews were conducted with plot owners and key informants regarding the uses of the weeds. We used indicator species analysis to group the weeds relative to land use gradients. Some 330 species in 67 families were classified as weeds. Plots under crops had higher weed species richness compared to unused plots (p < 0.007). Five key indicator weed species were identified including Cynodon dactylon in completely drained and seasonally grazed plots; Leersia hexandra in moist hydromorphic plots, Malva parviflora in partially drained cultivated plots, Oxalis corniculata in drained cultivated plots, and Typha domingensis in alkaline flooded wetlands. A list of indicator species and their importance to the local communities has been established. Despite negative impacts of weeds on crop production, local communities use most weeds as traditional leafy vegetable or as medication against various ailments for both humans and livestock. While the conversion of wetlands into crop fields leads to an ecological shift from (semi)natural to weed-dominated plant communities as is viewed by ecologists, rural folks use the weeds as sources of food and medicine. Sustainable use of wetlands is however advocated, for ecological integrity and sustainability of rural livelihoods.

Small wetlands in East Africa are increasingly converted into sites for agricultural production. The resulting changes in land use and cropping systems will impact on the wetlands’ vegetation. We characterized the plant communities in four wetlands of Kenya and Tanzania, each comprising four types of land use differentiated by the degree of anthropogenic disturbance (cropland, fallow, grazing land and unused). Since no syntaxonomical scheme was available as a reference, a first classification of vegetation units and the identification of diagnostic species is proposed. We collected 207 releves in the representative wetlands in relation to the current land uses. The plant communities were determined using a modified TWINSPAN classification. For each vegetation unit, diagnostic species were selected according to their fidelity index (phi coefficient). Floristic relationships between vegetation units were surveyed by nMDS ordination analyses. We identified 15 plant communities and selected 147 diagnostic species. The communities were differentiated into (1) semi-natural wetland vegetation (associated with less disturbed environments), (2) grassland and fallow vegetation, and (3) weed communities (associated with eu-hemerobic, drained and cultivated cropland). While the semi-natural vegetation was distinctly matched with unused fields, the differential matching of the other plant communities with land use types was less clear. According to the floristic similarity, the weed communities associated with cropland tended to be aggregated in the nMDS configuration while the semi-natural vegetation was dispersed. The results of the ordination did not differ when involving all species or only the selected diagnostic ones. As the plant communities described are rankless syntaxa, the establishment of a comprehensive syntaxonomic classification for African wetlands will require further vegetation surveys as well as their comparison with published data.

SWEA (agricultural use and vulnerability of small wetlands in East Africa) is a multidisciplinary project which task is to evaluate the effects of land use on the ecological and socio-economical functions of small wetlands in Kenya and Tanzania.In order to allow the availability of the collected data for further studies we stored them into SWEA-Dataveg (GIVD ID AF-00-006), a database stored in Microsoft Access (mdb-format).Because this project is dealing not only with vegetation science but also with geography, soil science, hydrology and socio-economy, the database also contains information related to these research fields.Additionally, some functional traits of the plant species occurring in the relevés are included in the species list.The sampling areas are concentrated in four localities, two of them in Kenya (Karatina and Rumuruti) and two in Tanzania (Malinda and Lukozi).The vegetation ecology group is dealing in the project with the classification of the vegetation according to species composition, the correlation of plant communities with environmental factors and land uses, and the survey of potential indicator species for the determination of the resilience of wetlands.Once finished the storage, we are considering an adaptation of SWEA-Dataveg into a TURBOVEG-format as well as its extension to further projects (e.g.SWEA phase II) and relevés collected from publications.

Small wetlands in Kenya and Tanzania cover about 12 million ha and are increasingly converted for agricultural production. There is a need to provide guidelines for their future protection or use, requiring their systematic classification and characterisation. Fifty-one wetlands were inventoried in 2008 in four contrasting sites, covering a surveyed total area of 484 km2. Each wetland was subdivided into sub-units of 0.5–458 ha based on the predominant land use. The biophysical and socio-economic attributes of the resulting 157 wetland sub-units were determined. The wetland sub-units were categorized using multivariate analyses into five major cluster groups. The main wetland categories comprised: (1) narrow permanently flooded inland valleys that are largely unused; (2) wide permanently flooded inland valleys and highlands floodplains under extensive use; (3) large inland valleys and lowland floodplains with seasonal flooding under medium use intensity; (4) completely drained wide inland valleys and highlands floodplains under intensive food crop production; and (5) narrow drained inland valleys under permanent horticultural production. The wetland types were associated with specific vegetation forms and soil attributes. Agricultural land use of wetlands was linked to their physical accessibility and the availability of adjacent upland areas, irrespective of wetland size or soil type.

In East Africa demographic growth, inter-generational inheritance of land, increasing land scarcity in the highlands areas, degradation of upland soils and inter-annual variability of rains is increasing cropping pressure on seasonal and nearly permanent wetlands. This study was carried out between 2008 and 2016 in order to find the changes of plant communities in Malinda wetland due to intensity of land use which results into changes of soil properties which impacts the functions of wetland ecosystems and on potential productivity of the soils. A first survey and plant communities characteristics in the area was firstly done in 2008 and a rapid appraisal with key informants was carried out to determine the characteristic land uses and to collect information on land use history of the area. Four land use types were determine which include unused part with domination of wetland vegetation, fairly used area with minimal grazing during dry period of the year, high intensity used area dominated by horticulture and fallow land which has been left after use or is used for yearly grazing. According to preferential sampling, 40 plots of size 10 m2 representing the main types of land uses were selected. In those plots all species and their estimated abundance as percentage cover were recorded. In each plot soil samples of the layer 0–15 cm were taken for soil chemical analysis. The same sampling techniques and procedure were repeated in the year 2016. The vegetation was classified by using hierarchical clustering technique and the relationships between species composition (land uses and plant communities) and soil properties of the wetland. The canonical correspondence analysis (CCA) was applied and the vegetation was classified into ten plant communities (clusters), five of them were weed communities of croplands while the remaining plant communities were from fallow, grazing land and unused part of wetland. There was no great difference in vegetation composition and plant communities obtained between the period of eight years. Both showed almost the same species composition and the plant communities were determined by soil exchangeable K, electric conductivity and pH according to ordination analysis.