Preliminary evidence of upland plant encroachment in high‐elevation wetlands of Volcanoes National Park, Rwanda

Abstract

Wetland ecosystems are increasingly altered by anthropogenic activities, with upland plant encroachment as one possible outcome. Here, we present preliminary evidence that encroachment by herbaceous and woody upland species is ongoing in five small Afromontane wetlands straddling high elevations (~2600-3400 m a.s.l.) in Volcanoes National Park (Rwanda). Although encroachment seems to commence at wetland edges it reaches waterlogged soils at wetland centres. This evidence of the spread of upland plants in these wetlands should be followed by additional research efforts focused on possible causes and consequences of this encroachment as well as the exploration of potential management and mitigation efforts. RésuméLes écosystèmes des zones humides sont progressivement altérés par les activités anthropiques, l'empiètement des plantes des hautes terres étant l'une des conséquences possibles. Nous présentons ici des preuves préliminaires de l'empiètement des espèces herbacées et ligneuses des hautes terres dans cinq petites zones humides afromontanes situées à cheval sur des altitudes élevées (~2600-3400 m a.s.l.) dans le Parc National des Volcans (Rwanda). Bien que l'empiètement semble commencer au bord des zones humides, il atteint les sols gorgés d'eau au centre des zones humides.Cette preuve de la propagation des plantes des hautes terres dans ces zones humides devrait être suivie d'efforts de recherche supplémentaires axés sur les causes et les conséquences possibles de cet empiètement, ainsi que sur l'exploration des efforts potentiels de gestion et d'atténuation.

Complexity of plant–pollinator interaction networks in East African high‐elevation wetlands

“…In each wetland, we walked 20 m width strip transects that started from a random corner of a wetland and gradually covered the entire wetland, an approach that should avoid biases in focal plant selection (e.g., by only observing visitors at plants with high levels of insect or bird activity). Focal plants, all of which were relatively common in the focal wetlands (Tuyizere et al, 2023), were Lobelia stuhlmannii Schweinf. ex Engl., Campanulaceae, inflorescence a dense raceme and corolla 0.3–0.4 cm long; Hypericum revolutum Vahl, Clusiaceae, flowers up to 3–8.6 cm diameter growing solitarily with five nectaries; Senecio mariettae Muschl., Asteraceaea, involucrum up to 0.5–0.6 cm and 7–13 ligulate flowers 0.55–1.2 cm long; Senecio maranguensis O.Hoffm, Asteraceae, involucrum up to 0.3–0.5 cm with 5–8 ligulate flowers 0.3–0.5 cm long; Galiniera coffeoides Delile, Rubiaceae, inflorescence of dense axillary cymes, corollas up to 0.1 cm long; and Pycnostachys goetzenii Gürke, Lamiaceae, thyrsic inflorescence with axillary cymes and corolla up to 1.2–1.7 cm long (Bartoš et al, 2015; Fischer & Killmann, 2008; Troupin, 1985; Sun et al, 1996).…”

“…There are two distinct rainy seasons in VNP (March-May and September-November) and two dry seasons (June-August and December-February) with annual rainfall reaching approximately 2200 mm and average daily temperatures ranging from approximately 9°C at lower elevations to 0°C at higher elevations (data extrapolated from 30 arc-second resolution CHELSA data; Karger et al, 2017Karger et al, , 2018. The study was conducted in six wetlands located at different elevations: Kabatwa (2546 m), Rugezi (2583 m), Malalo (2648 m), Ngezi (2861 m), Shegesha (3091 m), and Mudeli (3413 m; Figure 1; see Tuyizere et al (2023) for more information on these sites).…”