Plant Ecology

Tay, Jessica Y. L.; Zotz, Gerhard; Einzmann, Helena J. R.

doi: 10.1007/s11258-021-01186-6pmid: N/A

Vascular epiphytes represent almost 10% of all terrestrial plant diversity. Despite the extensive research on the functional ecology and challenges of epiphytic growth, there is still very little known on how exposure to mechanically induced stress affects the growth and development of epiphytes. Therefore, this study investigated the effect of such mechanical stress on the growth and biomass allocation of epiphytic bromeliads. Juvenile plants of two species were subjected to two types of mechanical stress in the greenhouse—permanent displacement and temporary, recurring mechanical flexing. ANOVAs were used to test possible treatment effects on growth, root–shoot ratio, root diameter, and root area distribution ratio. Contrary to previous studies on herbaceous plants, these bromeliads showed little to no change in root and shoot properties in either species. The root–shoot ratio increased in disturbed Guzmania lingulata plants, but not in Vriesea sp. Treatment effects on growth were inconsistent: a stress effect on growth was significant only in the first 2 months of the experiment in G. lingulata, whilst none of the stress treatments negatively affected growth in Vriesea sp. All disturbed plants showed some degree of curvature on their stems and leaves against the area of stress to obtain an upright position. This was probably related to the maintenance of a functional tank. This study provides quantitative and qualitative data to understand thigmomorphogenic responses of bromeliads to mechanical stress. Future studies could include field surveys to quantify on-site mechanical stresses and the corresponding morphological changes in vascular epiphytes.

Raghurama, Manaswi; Sankaran, Mahesh

doi: 10.1007/s11258-021-01188-4pmid: N/A

Invasive plants can impact nutrient cycling, potentially creating positive feedbacks for further invasion. We studied the impact of three woody nitrogen (N)-fixing invasive plant species on soil N-cycling and phosphatase activity in a montane tropical forest-grassland mosaic in the Nilgiri Biosphere Reserve in southern India, an ecosystem with > 100-year history of biological invasions. Soils were collected over a year from patches invaded by Acacia mearnsii, Cytisus scoparius, and Ulex europaeus, and from uninvaded grasslands, to assess inorganic N-availability and N-mineralization rates (using in situ open-top mineralization tubes). Phosphatase activity was measured from soils collected at the beginning of the growing season. Soils of invaded areas had higher inorganic N-availability and phosphatase activity than soils of uninvaded areas. Whilst net N-mineralization rates were unchanged between invaded and uninvaded sites, net nitrification rates were higher and net ammonification rates lower in invaded areas, particularly in the dry season. Impacts of C. scoparius and U. europaeus on these variables were similar to each other, and lower than the impacts of A. mearnsii. These results show that invasive N-fixers are significantly altering nutrient availability and cycling, and also changing the proportion of the forms of inorganic N available, in the Nilgiri grasslands. Restoration activities in these invaded grasslands should explore soil N management strategies such as soil C amendments and planting of specific native species, in conjunction with other strategies, to control invasive plants.

Fuentes-Jacques, Luis Javier; Hanson-Snortum, Paul; Hernández-Ortiz, Vicente; Díaz-Castelazo, Cecilia; Mehltreter, Klaus

doi: 10.1007/s11258-021-01187-5pmid: N/A

Ferns and lycophytes are the second and third largest lineages of vascular plants, yet our understanding of their interactions with phytophagous insects is very limited. In this study, we reviewed herbivorous insects, their feeding habits and host preferences on these two plant groups, searched for any evidence of coevolution, and discussed possible biases of our current knowledge on fern–insect interactions. We analyzed 2318 records of fern–insect interactions from 122 literature sources, based on the feeding habit of insects, fern taxa, and geographic location. We report interactions comprising 809 insect species (mainly Hemiptera, Lepidoptera, and Coleoptera) and 382 fern species (mainly Dennstaedtiaceae, Dryopteridaceae, and Pteridaceae). Leaf-chewers comprised over 50% of the species, followed by sap-sucking insects (29.1%) and spore feeders (6.5%). The overall interaction analyses revealed that the entire network was not significantly nested and had relatively low levels of specialization (H2′ = 0.24). The interaction networks of Coleoptera were the most specialized at family (H2′ = 0.40) and genus level (H2′ = 0.65), whereas six out of 10 most specialized insect families were Lepidoptera (d′ ≥ 0.44). At the genus level, all networks had a plant-biased asymmetry. Although insect specialists were common, few cases of coevolutionary radiation have been documented. We discuss the possible biases of our dataset, which also highlight gaps to fill in future research and suggest that many more fern-feeding insects remain to be discovered, especially sap-sucking, gall-forming, and spore-feeding insects on modern fern groups.

Dangremond, Emily M.; Hill, Christopher H.; Louaibi, Shahd; Muñoz, Ivette

doi: 10.1007/s11258-021-01190-wpmid: N/A

In boreal species, populations at a southern range edge are at risk of being extirpated due to rising temperatures from climate change and potentially from demographic factors that affect small populations. The ability to track climate through phenological responsiveness can affect survival and reproductive success, with implications for long-term population persistence. This study examines phenological responsiveness and fecundity in populations of an understory plant species, Trientalis borealis, in the Midwestern USA using herbarium specimens and field observations. Date of flowering was well predicted by the mean May temperature. We detected a shift in the mean flowering date for populations north of latitude 45° N of an average of 1.4 days earlier per decade. We did not find shifts in mean flowering date for populations south of 45° N. Trientalis borealis exhibits phenological responsiveness differently in different parts of its range. In populations north of latitude 45° N, T. borealis advances its date of flowering, on average, by approximately 3 days for every 1 °C increase in mean May temperature. In populations south of 45° N, T. borealis advances its flowering date less than 1 day for every 1 °C increase in mean May temperature. Flowering and seed set increased along a latitudinal gradient away from the range edge. If population growth is limited by seed production in this species, this suggests that populations near the southern range limit are not performing well, perhaps due to direct effects of warming, a lack of phenological responsiveness that exacerbates exposure to warming, or a lack of genetic diversity.

Sofi, Irfan Iqbal; Verma, Shivali; Charles, Bipin; Ganie, Aijaz H.; Sharma, Namrata; Shah, Manzoor A.

doi: 10.1007/s11258-021-01189-3pmid: N/A

Climate change, land-use changes and other anthropogenic pressures are globally the major drivers of biodiversity decline with profound implications, especially for the fragile Himalayan ecosystems. These drivers, if factored into the biodiversity conservation models, significantly improve their reliability and help a great deal prioritise habitats for better management. Here we focussed on an important medicinal plant species (Trillium govanianum), endemic to Himalayan region that is beset with the twin challenge of climate change and growing human footprint. We predicted the current and future projection of the distribution range of this species using SDM tool ‘MaxEnt’ supplemented with ‘Zonation’ software and ‘human pressure index’. Decrease in the potential geographic range of T. govanianum, with a narrow room for conservation due to anthropogenic pressures in the predicted suitable habitats, was clearly revealed from our results. We identified the precise zones within the predicted suitable habitats under the future climatic scenarios (2050 and 2070) for priority conservation to endure the impact of climate change and growing human pressures. These results hold considerable promise in designing the effective conservation strategies for the target species. In the context of post 2020 biodiversity outlook, we advocate augmenting the species distribution models with human footprint index, zonation analysis and the climate change scenarios, to realistically meet the desired conservation targets.

Holeštová, Anežka; Douda, Jan

doi: 10.1007/s11258-021-01191-9pmid: N/A

River valleys are considered natural corridors for migration of plant species; however, there is a lack of studies confirming higher colonisation rates of plant species in these areas. We compare plant species richness between ancient and recent forests (developed during and after the nineteenth century) and those located in a river valley with those located outside the river valley. We hypothesise that, close to a river, higher plant species richness will be associated with recent forests, thus indicating a higher colonisation rate. The study area includes parts of the Elbe River Valley and a landscape outside the river valley in the Czech Republic. We sampled an equal number of recent and ancient forests (20/20), but lying at different distances from the river. We used generalised linear models to test the effect of distance from the river in dependence upon forest continuity (recent/ancient forest) on two plant species richness categories, i.e. richness of forest species and overall species richness. Outside the river valley, higher richness of forest species was associated with ancient forests, whereas overall species richness was comparable. In the river valley, richness of forest species as well as overall species richness was higher in the recent forests. Recent forests in the river valley were more saturated by plant species than those outside the river valley, indicating that in the river valley, the colonisation rate of plant species is higher. These results confirm the importance of river valleys as natural corridors for migration of plant species.

Amaral, Aryanne Gonçalves; Bijos, Natália Rodrigues; Moser, Pamela; Munhoz, Cássia Beatriz Rodrigues

doi: 10.1007/s11258-021-01193-7pmid: N/A

We evaluated the influence of soil properties, climate, and space on the distribution of herbaceous-shrub species in the Cerrado biome. We determined species composition, cover, and richness along 25 line transects in Cerrado (savanna-like vegetation) in three protected areas with different soil types and altitudes. Soil physicochemical properties, climate, and geographic coordinates were included in the analysis as species distribution predictors. We observed high species richness in all sites, especially in the Chapada dos Veadeiros National Park (PNCV) and the Brasília National Park (PNB), with over 200 species each. Only 16% of the species were recorded in all sites, indicating high species turnover for Cerrado herbaceous-shrub layer. The transformation-based redundancy analysis indicated that differences in the herbaceous-shrub flora were associated with soil physicochemical properties and climate. Species composition was primarily influenced by higher annual precipitation for PNCV, by the highest clay content and soil pH for PNB, and by greater annual mean temperature for Terra Ronca State Park (PETER). Soil, climate, and their spatially structured fraction explained herbaceous-shrub species distribution in the Cerrado (43.6%). The spatial variation which is not correlated to the environment adds only 4.5% to the model. Taken together, our findings provide a basis for understanding the distribution patterns of herbaceous-shrub species across climate, soil, and geographic distance. These findings are critical for the development of strategies to protect biodiversity and endangered species in the Cerrado, especially in the region most threatened by deforestation (PETER).

Azuma, Wakana A.; Komada, Natsuki; Ogawa, Yuya; Ishii, Hiroaki; Nakanishi, Akira; Noguchi, Yuiko; Kanzaki, Mamoru

doi: 10.1007/s11258-021-01192-8pmid: N/A

Large, trees have survived for a long time, and their complex crown structure can serve as habitat for epiphytic plants. Canopy plants are not as well studied in the temperate zones as in the tropics, because many of them are accidental epiphytes, epiphytic individuals of normally terrestrial species. We hypothesized that the canopy can serve as a refuge for terrestrial species that have difficulty establishing on the ground (e.g., insufficient light, deer over-browsing), promoting and conserving forest species diversity. Terrestrial species may also vary in their ability to adapt to a wide range of canopy growth conditions. Here, we investigated canopy vascular plants hosted on a large Cercidiphyllum japonicum tree in a temperate old-growth forest, Japan. The canopy plant community was diverse comprising 39 vascular plant species (6 of which were threatened species), including 31 accidental epiphytes and 8 obligate epiphytes. We found at least 14 species could escape deer over-browsing by establishing in the canopy. Most accidental epiphytes were found on multiple and large reiterated trunks bifurcated from the main trunk as well as on large horizontal branches. Leaves of canopy plants had higher nitrogen concentration compared to those of plants on the ground, and higher water-use efficiency with increasing height was achieved by controlling transpirational water loss. Our results show one large tree crown can be defined as a local hotspot for current and future plant species diversity in a temperate old-growth forest, reinforcing its ecological value for conservation purposes.

Ibe, Karin; Walmsley, David; Fichtner, Andreas; Coners, Heinz; Leuschner, Christoph; Härdtle, Werner

doi: 10.1007/s11258-021-01195-5pmid: N/A

Heinze, Johannes

doi: 10.1007/s11258-021-01194-6pmid: N/A