Grasses of the Isalo National Park, Madagascar – checklist, origins, and significance

Grasses are one of the best documented plant families worldwide in terms of taxonomy, but they are still poorly known in Madagascar. Our understanding of their diversity remains incomplete since grasses and grasslands are assumed by many tobe weeds and degraded wastelands. This project aimed to list thegrasses in Isalo National Park (NP) in order to understand theirdiversity and endemicity, as well as the history of Isalo’s grasslands. Examination of herbarium specimens and new field inventories allowed us to confirm 589 records of grass occurrences in ourstudy area. They were assigned to 112 species, of which 38 species are new records for Isalo NP. The Isalo grass flora includes seven of the eleven Poaceae subfamilies present in Madagascar and is particularly rich in Panicoideae, which make up 65% of the species. Nearly 22% of the grass species of Isalo are endemic to Madagascar, of which three species and one variety are restricted to Isalo massif, including two unusual ground cover species Tristachya humbertii A.Camus and Tristachya [Isalus isalensis]. Open grasslands harbour the highest diversity of grass species, followed closely by riparian forests. The history of the management of Isalo NP by the Bara people, as well as the endemism and the native origin of its grasses and  other species are consistent with an ancient origin of Isalo’s ecosystems. We urge that the conservation of Isalo’s grassy ecosystems, as well as that  of the plants and animals that inhabit them be prioritized.Les graminées sont parmi les familles de plantes les mieux documentées au niveau mondial en termes de taxonomie, mais sont encore mal  connues à Madagascar. Notre compréhension de leur diversité reste incomplète, vu que les graminées et les savanes sont considérées par beaucoup comme des mauvaises herbes et des friches dégradées. Ce projet visait à établir une liste des graminées connues du Parc National (PN) de l’Isalo, afin de comprendre leur diversité et leur endémicité, ainsi que l’histoire des écosystèmes herbeux de l’Isalo. L’examen des spécimens d'herbiers et les nouveaux inventaires sur terrains nous ont permis de générer 589 occurrences de graminées de notre site d’étude. Elles ont été  attribuées à 112 espèces de Poaceae, dont 38 sont de nouvelles collectes pour le massif de l’Isalo. La flore herbacée du massif de l'Isalo comprend  sept des onze sous-familles de Poaceae présentes à Madagascar et est particulièrement riche en Panicoideae qui représentent 65% des espèces.  Près de 22% des espèces de graminées de l’Isalo sont endémiques de Madagascar, dont trois espèces et une variété sont restreintes à Isalo, y  compris les deux espèces de plantes couvre-sols inhabituelles Tristachya humbertii A.Camus et Tristachya [Isalus isalensis]. Les prairies ouvertes  abritent la plus grande diversité d'espèces de graminées, suivies de près par les forêts ripicoles. L’histoire de la gestion du PN de l’Isalo par les  habitants de la région du groupe Bara, ainsi que l’endémisme et l’origine autochtone de ses graminées et autres espèces sont cohérents avec une  origine ancienne des écosystèmes de l’Isalo. Nous préconisons instamment que la conservation de ces prairies et savanes de l'Isalo, ainsi que les plantes et les animaux qui les habitent soit priorisée

The genus Tristachya (Poaceae: Panicoideae) in Madagascar.

We present a revision of the three species of in Madagascar. The tussock-forming is a rare endemic of the quartz outcrops in the Itremo Protected Area. The rhizomatous and are common components of the sandstone outcrop vegetation in the Isalo National Park. A new combination is made. Descriptions, conservation assessments, illustrations, and a distribution map are presented

Land‐use intensification increases richness of native and exotic herbaceous plants, but not endemics, in Malagasy vanilla landscapes

Abstract Aim North‐eastern Madagascar is a hotspot of plant diversity, but vanilla and rice farming are driving land‐use change, including slash‐and‐burn management. It still remains unknown how land‐use change and land‐use history affect richness and composition of endemic, native and exotic herbaceous plant species. Location North‐eastern Madagascar. Methods We assessed herbaceous plants along a land‐use intensification gradient ranging from unburned land‐use types (i.e. old‐growth forest, forest fragment and forest‐derived vanilla agroforest) to burned land‐use types (i.e. fallow‐derived vanilla agroforest, woody fallow and herbaceous fallow) and rice paddy. We compared land‐use types and analysed the effects of land‐use history, canopy closure and landscape forest cover on species richness. Additionally, we analysed species compositional changes across land‐use types. Results Across 80 plots, we found 355 plant species (180 native non‐endemics, 57 exotics, 60 endemics and 58 species of unknown origin). Native and exotic species richness increased with increasing land‐use intensity, whereas endemics decreased. Unburned land‐use types had higher endemic species richness (4.28 ± 0.37 [mean ± SE]) than burned ones (2.4 ± 0.21). Exotic and native species richness, but not endemics, decreased with increasing canopy closure. Increasing landscape forest cover reduced exotic, but not native or endemic richness. Species composition of old‐growth forests was unique compared to all other land uses and forest‐derived, not fallow‐derived vanilla agroforests, had a similar endemic species composition to forest fragments. Main conclusions Our results indicate that old‐growth forests and forest fragments are indispensable for maintaining endemic herbaceous plants. We further show that the land‐use history of agroforests should be considered in conservation policy. In forest‐derived vanilla agroforests, management incentives are needed to halt loss of canopy closure, thereby maintaining or even enhancing endemics. In conclusion, considering species origin (endemic, native and exotic) and composition is essential for the identification of suitable management practices to avoid irreversible species loss

Geographical structure of genetic diversity in Loudetia simplex (Poaceae) in Madagascar and South Africa

Ecologically dominant species are primary determinants of ecosystem function, especially in grassy ecosystems, but the history and biology of grassy ecosystems in Madagascar are poorly understood compared to those of Africa. Loudetia simplex is a C4 perennial grass that is adapted to fire and common to dominant across Africa. It is also widespread across central Madagascar in what are often thought to be human-derived grasslands, leading us to question how recently L. simplex arrived and how it spread across Madagascar. To address this, we collected population genetic data for 11 nuclear and 11 plastid microsatellite loci, newly developed for this study, for > 200 accessions from 78 populations of L. simplex, primarily from Madagascar and South Africa. Malagasy and African populations are genetically differentiated and harbour distinct plastid lineages. We demonstrate distinct geographically clustered diploid, tetraploid and hexaploid groups. The Malagasy hexaploid populations cluster into northern and southern types. In South Africa, diploid populations in the Drakensberg are distinct from tetraploid populations in north-eastern South Africa. Different genetic clusters are associated with significantly different precipitation and temperature. We conclude that L. simplex is native to both Madagascar and South Africa, probably with a single colonization event from Africa to Madagascar followed by pre-human diversification of L. simplex populations in Madagascar

Evolutionary history, traits, and weediness in Digitaria (Poaceae: Panicoideae).

Digitaria is a large pantropical genus, which includes a number of economically problematic agricultural weeds. Difficulties in species identification and the circumscription of the genus have previously hindered progress in understanding its evolution and developing a stable classification. We investigate the evolutionary history of Digitaria by combining two approaches: (i) phylogenetic analyses of the currently available Sanger sequence data with previously unpublished sequences mainly from South East Asia, and (ii) newly generated genomic data from low-copy nuclear genes obtained using the Angiosperms353 probe kit, with new data mainly from Madagascar. Both methods gave congruent results. The combination of these results allowed us to confirm a new clade structure within Digitaria lineages, in partial agreement with the previous morphology-based classifications. We confirm that Digitaria as traditionally circumscribed is not monophyletic, comprising Anthephora, Baptorhachis, Chaetopoa, and Chlorocalymma. We present an inference of key character evolution with morphological support for clades with spikelets arranged in binate and ternate groups, with variable trichome morphology, spikelet length, and culm length. Geographical clade structure is also observed. No phylogenetic signal of weedy function was observed

COFAC-Col: A Cervical Cancer Control Networking Initiative in Five French-Speaking African Countries

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