Large herbivores suppress liana infestation in an African savanna

African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana–tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.

Touch me carefully: a step towards understanding morphological diversity in the South American spiny sunflowers (Compositae, Barnadesioideae)

The subfamily Barnadesioideae (Compositae) is endemic to South America, comprising 10 genera and 80 species of mostly spiny herbs, subshrubs, shrubs, trees, or woody vines distributed from Venezuela to Argentina. Three genera, Dasyphyllum (27 species), Chuquiraga (22 spp.) and Barnadesia (19 spp.) contain 85% of the species, while the other seven genera (Archidasyphyllum, Arnaldoa, Doniophyton, Duseniella, Fulcaldea, Huarpea, and Schlechtendalia) are represented by up to three species each. Most species are found in xeric areas in the Andean and Patagonian regions—as in the Páramos, Puna and Patagonian steppe vegetation—with a secondary center of diversity in eastern South America. Previous phylogenetic hypotheses have clarified the relationships within the subfamily, showing that there are many non-monophyletic groups in different taxonomic ranks. As a result, taxonomic changes have been proposed over recent decades in order to reflect classifications comprising only monophyletic groups. In the present study, we provide a generic synopsis of the subfamily Barnadesioideae based on the most recent generic circumscriptions, including a key, expanded morphological descriptions, information on geographical distribution and habitat, photographs and taxonomic notes for all genera.

Liana optical traits increase tropical forest albedo and reduce ecosystem productivity

Lianas are a key growth form in tropical forests. Their lack of self-supporting tissues and their vertical position on top of the canopy make them strong competitors of resources. A few pioneer studies have shown that liana optical traits differ on average from those of colocated tree. Those trait discrepancies were hypothesized to be responsible for the competitive advantage of lianas over trees. Yet, in the absence of reliable modelling tools, it is impossible to unravel their impact on the forest energy balance, light competition and on the liana success in Neotropical forests. To bridge this gap, we performed a meta-analysis of the literature to gather all published liana leaf optical spectra, as well as all canopy spectra measured over different levels of liana infestation. We then used a Bayesian data assimilation framework applied to two radiative transfer models (RTMs) covering the leaf and canopy scales to derive tropical tree and liana trait distributions, which finally informed a full dynamic vegetation model. According to the RTMs inversion, lianas grew thinner, more horizontal leaves with lower pigment concentrations. Those traits made the lianas particularly efficient at light interception and completely modified the forest energy balance and its carbon cycle. While forest albedo increased by 14% in the shortwave, light availability was dramatically reduced in the understory (-30% of the PAR radiation) and soil temperature decreased by 0.5 degree Celsius. Those liana-specific traits were also responsible for a significant reduction of tree (-19%) and ecosystem (-7%) gross primary productivity (GPP) while lianas benefited from them (their GPP increased by +27%). This study provides a novel mechanistic explanation to the increase in liana abundance, new evidence of the impact of structural parasitism on forest functioning, and paves the way for the evaluation of the large-scale impacts of woody vines on forest biogeochemical cycles.

КЛАСИФІКАЦІЯ РОДУ CLEMATIS L. ТА ІНТРОДУКЦІЯ В КРЕМЕНЕЦЬКОМУ БОТАНІЧНОМУ САДУ

The article highlights the findings of the study of the classification of species of the genus Clematis, the history of the study and some aspects of their introduction into the Kremenets Botanical Garden. The object of the study was the introduced species of the genus Clematis. Analysis of bioecomorphs of introducers, and the biometric indicators of morphological observations of plants. The word «Clematis» came into Latin terminology from the ancient Greek word «Clema» meaning tendril. Dioscorides first mentions this term when describing twisted plants. The generic name was first used by K. Linnaeus in «Species plantarum». Lominos have been cultivated in European gardens for over 400 years. Species of the genus Clematis are found in 28 of the 34 floristic regions around the globe. The life forms of plants are very diverse (from semi-shrubs to woody vines). These plants retain their decorative qualities until late autumn and form, especially when planted on the lawn, bright spots of various colors, and, therefore, have a decorative effect, decorative leaves and flowers, and even seeds, during the growth season give rapid shoot growth. In the Kremenets region, this culture is little known, as the range of species, as well as their bioecological features in different areas of introduction are poorly studied. Clematis has long been used in ornamental horticulture, while in the landscaping of cities Clematis is not used and is most common in the gardens of amateur gardeners. The growing season during the introduction test is 187-238 days. The studied species bloom for up to 85 days and some species have repeated flowering. The beginning and duration of the phases of growth and flowering differ significantly for different species and varieties of Clematis and depend on biological characteristics, geographical origin, as well as agricultural techniques. It is usually propagated by seeds and vegetatively - by layering, dividing the bush, cuttings or grafting, seeds are often propagated species with small flowers; their seeds germinate fast in spring. For species with large seeds, the germination period is extended by 80 (500) days.

Three new species of Lycianthes (Solanaceae) from Panama

Three Panamanian cloud forest species in the genus Lycianthes are newly described: L. coloradensis, from the Ngäbe-Buglé Comarca; L. fortunensis from Chiriquí Province, Veraguas Province, and the Ngäbe-Buglé Comarca; and L. talamancensis from Bocas del Toro and Chiriquí provinces. All three species are woody vines with tan, yellow, or orange-brown multangulate-stellate trichomes and entire to nearly entire white to purple corollas. In terms of vegetative morphology and trichome characteristics, L. coloradensis most closely resembles L. purpusii of Mexico, Guatemala, and Honduras, L. fortunensis resembles the widespread L. multiflora, and L. talamancensis resembles L. hortulana of Honduras, El Salvador, and Nicaragua. This article provides species descriptions, maps of geographic distributions, specimen images of each species, and comparison tables of morphological characters used to separate L. coloradensis, L. fortunensis and L. talamancensis from similar species.

Rhythm of seasonal development of woody vines of the Vitaceae Juss. family in the conditions of introduction in the Right-bank Forest Steppe of Ukraine

To investigate the phenorhythmics of introduced woody vines of the family Vitaceae of the genus Ampelopsis Michx. and Parthenocissus Planch., to determine the possibilities of their use in cultural phytocenoses of the Right-Bank Forest-Steppe of Ukraine. Methods. Phenological observations were conducted during 2012–2014. Plants of the investigated taxa belong to the collection fund of the exposition-collection area “Climbing plants” of the M. M. Hryshko National Botanic Garden of the NAS of Ukraine. The distribution by phenogroups of the investigated plants and the construction of the phenospectrum of seasonal development were performed using appropriate methods. Results.The end of the vegetation of the representatives of the genus Parthenocissus occurred before the end of the growing season 16.X ±6,13 (P. inserta)–23.X ±7,41(P. tricuspidata Veitchii’), and in plants of the genus Ampelopsis coincided with this date 4.XI ±7,36 (A. aconitifolia f. glabra)–13.XI ±7,85(A. brevipedunculata). Flowering of the representatives of the genus Parthenocissus lasted 22,3 ±4,1 (P. tricuspidata Veitchii’)–81,7±2,1 (P. quinquefolia f. engelmannii) days, and plants of the genus Ampelopsis – 98,3±7,7 (A. aconitifolia)–107,0 ±7,3 (A. brevipedunculata) days. The period from tying to ripening of fruits in representatives of the genus Parthenocissus was 47,0 ±5,66 (P. quinquefolia)–59,0 ±3,74 (P. tricuspidata Veitchii’) days, and plants of the genus Ampelopsis – 35,7 ±3,77 (A. aconitifolia f. glabra)–41,3±5,79 (A. brevipedunculata) days. Conclusions. It was found that members of the genus Parthenocissus are characterized by timely entry into the period of winter dormancy, shorter flowering period and longer fruit ripening compared with plants of the genus Ampelopsis. Given the native areals of plants of the studied species, which cover dry with low rainfall and cold wet regions, we can conclude that they are all characterized by high plasticity and resistance to environmental conditions, as phenological observations noted their annual flowering and fruiting. This indicates a high degree of compliance of their genetically fixed phenorhythmics with the climatic conditions of the Right-Bank Forest-Steppe of Ukraine.