Plant Ecology最新文献

The population size of the Rubus asirensis has declined significantly over the previous century across its geographical region. This decrease is related to changes in natural resources, such as water and foraging site capacity, due to continuous climate change. We used species distribution models (SDMs) to study R. asirensis’s reaction to projected climate change over the next few decades. To reduce uncertainty and bias in our SDM predictions, we fitted ensemble SDMs with freshly developed climatic data based on more accurate climate models and diverse dispersal scenarios. In Abha, Tanumah town, Al-Numas in Asir mountains, and Al-Baha province southwest of Saudi Arabia, our SDMs revealed a potential presence of R. asirensis. Furthermore, our models anticipated that the distribution range of R. asirensis would drop by more than 25% during the next few decades. Our findings advocate for immediate conservation action of reintroduction and in situ conservation planning.

Seed predation may reduce the quantity and diversity of seeds and limit seedling recruitment. However, the extent to which seed predation may depend on the species and vegetational microhabitat has been less studied. We studied seed predation of woody species in the Mediterranean-type ecosystem of central Chile. We explored if interspecific differences in the magnitude of seed predation depends on the seed mass, evaluated the role vertebrate herbivores in seed predation, and examined if seed predation depends on the vegetation patch type. We conducted a seed removal experiment with eight woody species in three vegetation patch types (forest, shrub, and open) and replicated in two localities. We established exclosures for birds and mammals (wire cages covering 1 m²) and evaluated seed removal during 18 days within and outside of them. We also evaluated the soil seed availability by collecting soil samples inside and outside these exclosures after 2 years of exclusion in the same vegetation patches, adding other three localities. Exclosures significantly reduced the number of seeds removed in all species and patch types of both localities (overall 24.02% of removal in non-exclusion areas vs. 1.77% in exclosures). The magnitude of seed predation was negatively related to the seed mass of species. Exclosures significantly increased the number and species richness of seeds in the soil of forest and shrub patches of four localities. The results suggest that seed predation is mainly produced by vertebrates, affects several woody species from central Chile, and is more common in forest and shrub patches.

Combatting the biodiversity crisis through management and conservation requires specific information on the basic biology of species in decline. The Eastern pasqueflower, Pulsatilla patens, has declined drastically in Europe and in Finland is currently confined to a few locations. The aim of this study was to assess which factors influence fitness-related traits of P. patens and a hybrid species P. patens × vernalis. To this end we recorded morphological and environmental variables over a three-year period on individually marked P. patens and hybrid individuals in eight locations in southern Finland. The number of flowers decreased significantly each year for P. patens while for the hybrid there was first an increase and then decrease. Hybrids produced on average more flowers than P. patens individuals and the share of flowering individuals was higher in hybrids than in pure pasqueflowers. In general, for both P. patens and the hybrid, larger plant diameter, cooler and drier conditions and greater canopy openness positively affected number of flowers and flowering probability, although some species-specific differences were evident with a preference for greater canopy density for P. patens than the hybrid. Although our results support current conservation practices of creating more open environments to benefit flowering of P. patens, there also appears to be a limit to the amount of direct sunlight P. patens will tolerate, thus warranting caution. At present, the hybrid does not appear to be of immediate concern to the endangered P. patens, although continued monitoring of the populations is recommended.

The exotic ornamental tree Senna spectabilis (DC.) H. S. Irwin and Barneby has invaded various Protected Areas of the Nilgiri Biosphere Reserve including the Wayanad Wildlife Sanctuary in India creating a significant threat to biodiversity. This study examined the allelopathic potential and heterotoxicity of invasive S. spectabilis leaf extract by bioassay under laboratory conditions and identified its allelochemicals using HRLC-ESI–MS (QTOF) analysis. The bioassay experiment with test plant species including Vigna radiata (mung bean), Cicer arietinum (chickpea), and Amaranthus cruentus (red amaranth) was conducted in the laboratory and the methanolic leaf extract found to exhibit the greatest inhibitory activity. The percentage of inhibition of plumule growth by methanolic leaf extract on V. radiata, C. arietinum, and A. cruentus were 82%, 86%, and 99%, respectively. Phenol and proline content were significantly increased in germinated seedlings treated with even a quarter strength of leaf extract. Further by HR-LCMS analysis fifteen important allelochemicals were identified including phenolic compounds, flavonoids, anthraquinone, benzoic acid derivatives, and cinnamic acids. A soil sterilization experiment was used to examine the role of soil microbes in the phytotoxicity of leaf leachate. No significant variations exhibited in the phytotoxicity. The full strength of leaf leachate inhibited the shoot length of B. bambos by 52% in the sterile and 48% in the non-sterile soil, whereas it was 74 and 68%, respectively, in V. radiata. Further studies in the process of allelochemical release and their mode of action may confer a more lucid knowledge concerning the invasion mechanisms of S. spectabilis through allelopathy, guiding to practical management strategy.

Soluble components leach rapidly during the early stage of litter decomposition and represent the earliest nutrient input to the soils after leaf fall, which have significant importance for the material cycle in ecosystems. However, the concentration characteristics and primary drivers of litter soluble components at the global scale remain unclear. Therefore, 303 observations of water soluble compounds (WSCs), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) and auxiliary plant functional traits (mycorrhizal association, taxon division, plant life form, and leaf type) were collected worldwide. Linear mixed-effect models were used to examine the relative effects of climate, soil, topography, and plant functional traits on the concentration of different soluble components of litter. The average concentrations of leaf litter WSCs, DOC, and DON were 22.50, 4.15, and 0.01%, respectively. The concentration of WSCs in leaf litter was regulated by plant functional traits and soil properties, with mycorrhizal association and soil microbial biomass carbon to nitrogen ratio as the primary drivers. The concentration of DOC in leaf litter was influenced by climate and topography, with elevation being the most important factor. Our study reveals the global patterns and drivers of different soluble components in leaf litter, which is crucial for predicting litter decomposition under future climate change.

Plants optimize traits to adapt to an environment, forming the basis of trait–environment relationships. However, it is unclear whether these relationships are evolutionarily and spatially robust, particularly in species-rich tropical forests. In this study, we examined the relationships between species elevational distribution and traits that represent the major axes of resource-use-strategies (leaf traits, maximum height, and wood density), focusing on Fagaceae, which occupies diverse elevational niches in tropical montane forests. We investigated two tropical regions (northern Borneo [NB] and northern Thailand [NT]) with different environmental gradients along elevation. NB has increasing temperatures at lower elevations with high levels of rainfall at all elevations, whereas NT has increasing temperatures and dry soil, particularly during the dry season at lower elevations. Different traits were related to the species distribution in the two regions. In NT, species with high desiccation tolerance in the leaf and stem were distributed at drought-prone low elevations. These species do not occur at stress-moderate high elevations, likely because of strong resource competition. In NB, species with durable leaves were associated with harsh higher elevations and wider elevational ranges. The predictions of elevational ranges by some leaf traits contrasted between the two regions. These results suggest that the influence of traits on growth and survival largely depends on resource gradients along elevation and, presumably, water availability. Our results raise concerns about using a single trait to predict the future distribution of species under climate changes in different environments.

Translocation of rare plant species to their original habitat is an increasingly used conservation approach around the world. However, we lack information on the factors affecting translocation outcomes. Research on the influence of seed provenance on plant fitness is limited in the context of translocations using plug plants. This study aims at exploring the effect of seed origin on vegetative and floral performances of three species (Arnica montana L., Campanula glomerata L. and Helichrysum arenarium (L.) Moench) in eight populations (of 500 to 700 individuals each from two to five different origins) translocated in Belgium. We recorded for 4 to 8 years the survival of each plant, its fertility, the length of the longest flower stem or rosette diameter (depending on the species), the number of flower stems and the number of flowers (or flower heads) per flower stem. The results show that the origin of the seeds significantly impacted the three species studied for at least three performance variables, but no origin was superior to the others in all the measured variables. A combined effect of seed origin, site and year has also been observed. The seed origin effect persisted over the years, suggesting that this factor is at least as important as habitat suitability or environmental stochasticity. These results show the importance of the choice of the source population in the context of translocations and strongly support a multisource and multisite approach for future translocations of threatened species.

The C3–CAM (crassulacean acid metabolism) intermediate species Yucca gloriosa L. is invading coastal dunes in central Italy, causing a loss in biodiversity and habitat. In order to investigate its competitive success, a number of ecophysiological traits were analysed: CAM activity (through carbon isotope composition, δ¹³C, and cell acidification), photochemical efficiency of PSII (operating and maximum photosystem II quantum yield), stomatal conductance, relative water content, and succulence index (SI). Analyses were conducted over the course of one year, to assess yucca’s response to seasons and the shoreline-inland ecological gradient. The species displayed high physiological plasticity, a factor that might prove decisive in enhancing carbon fixation and water-use efficiency across the seasons, and accordingly its level of invasiveness. Temperature seemed crucial in controlling photosynthetic metabolism, a fact borne out by seasonal changes seen in δ¹³C and SI. Some stress symptoms appeared in winter, including a slight reduction of photochemical performance, and the shoreline–inland ecological gradient did not have any significant effects. All the plants analysed were intermediate C3–CAM: given that yucca cannot reproduce sexually in Europe, the entire population of the area studied might conceivably share the same carbon fixation pathway. The results obtained may help afford a better understanding of the ecophysiological features of Y. gloriosa in a Mediterranean dunal ecosystem, along with the dynamics of the invasion process, allowing a more efficient approach to be adopted in programmes for managing this environment.

The industrial footprint of oil and gas extraction in Alberta, Canada dissects the landscape in a network of linear and polygonal disturbances such as roads and well pads. The changes to biotic and abiotic factors beyond the boundaries of these disturbances into the adjacent ecosystem are called edge effects. A common assumption is that edge effects are proportional to the width of the disturbance, with wider disturbances leading to deeper effects into the forest. The objective of this study is to compare edge effects on plant composition, seed dispersal distance, seed weight, and microclimate across three disturbance types: narrow (< 20 m) and wide (> 20 m) roads, and well pads (> 100 m; 1.9 ha) in upland boreal forests in the oil sands region of north-eastern Alberta. We sampled 1 m² plots at six distances (0 m, 10 m, 15 m, 25 m, 50 m, and 75 m) along transects running perpendicular from the disturbance edge into the forest. Edge effects for plant communities were contained at the disturbance edge for all disturbance types considered. Understory species richness was lower at the disturbance edge and was dominated by introduced species and species with lighter seeds and with medium-distance dispersal mechanisms. Disturbance edges were characterized as having higher soil moisture content, higher soil temperature, and a thinner organic matter layer compared to the forest interior (> 10 m). With no effect of disturbance width on width of edge effects, our study does not support the assumption that narrower disturbances will necessarily result in narrower edge effects for vegetation and abiotic metrics.

Abstract

Bird-pollinated flowers typically appear ‘red’. Fuchsia excorticata (Onagraceae), a gynodioecious tree species endemic to New Zealand, is a notable exception. It produces ‘green’, cauliflorous flowers at early stages in flower ontogeny, when pistils are receptive. Flowers later turn ‘red’ as they lose their receptivity. We conducted field observations and spectrographic analyses to test whether: (1) receptive, green-phase flowers are actually more conspicuous to avian pollinators against their natural backgrounds than unreceptive, red-phase flowers, (2) green-phase flowers produce more nectar, and (3) relationships between flower conspicuousness and nectar production are similar in females and hermaphrodites. Results showed that the reflectance properties of green-phase flowers sharply contrast ‘orange’ tree bark, their natural visual background, rendering them more conspicuous to the avian eye than red-phase flowers. Green-phase flowers also produced more nectar than red-phase flowers as an honest signal of rewards. Similar results were observed in both female and hermaphrodite plants. Overall results provide an unusual example of reversed flower-background colour contrasts, with ‘reddish’ hues being incorporated into the visual backgrounds of floral displays rather than being associated with the flowers themselves. They also illustrate that flower conspicuousness can serve as an honest signal of nectar rewards to pollinators.