scholarly journals Indication of a reduction in the cover of thin-leaved plants in Danish grasslands over an eight-year period

2019 ◽  
Author(s):  
Christian Damgaard

AbstractAcross four grassland habitat types, the cover of thin-leaved plants was found to decrease significantly, but generally only limited trait selection was observed on leaf traits (SLA and LDMC) in a study of an extensive Danish grassland vegetation dataset from an eight-year period. The mostly negative result of this study may partly be due to the relatively conservative analysis, where the continuous plant trait variables are used for grouping plant species into functional types, which are then treated as dependent variables. This procedure is in contrast to most other analyses of trait selection, where it is the community weighted mean of the traits that is used as the dependent variable. However, it is not the traits, but rather individual plants that are sampled and, consequently, it is important to consider the sampling of species abundance in the statistical modelling of plant traits. This misapprehension has not received sufficient proper attention in the plant trait literature.

2017 ◽  
Vol 21 (3) ◽  
pp. 1421-1438 ◽  
Author(s):  
Chuan Yuan ◽  
Guangyao Gao ◽  
Bojie Fu

Abstract. Stemflow transports nutrient-enriched precipitation to the rhizosphere and functions as an efficient terrestrial flux in water-stressed ecosystems. However, its ecological significance has generally been underestimated because it is relatively limited in amount, and the biotic mechanisms that affect it have not been thoroughly studied at the leaf scale. This study was conducted during the 2014 and 2015 rainy seasons at the northern Loess Plateau of China. We measured the branch stemflow volume (SFb), shrub stemflow equivalent water depth (SFd), stemflow percentage of incident precipitation (SF %), stemflow productivity (SFP), funnelling ratio (FR), the meteorological characteristics and the plant traits of branches and leaves of C. korshinskii and S. psammophila. This study evaluated stemflow efficiency for the first time with the combined results of SFP and FR, and sought to determine the inter- and intra-specific differences of stemflow yield and efficiency between the two species, as well as the specific bio-/abiotic mechanisms that affected stemflow. The results indicated that C. korshinskii had a greater stemflow yield and efficiency at all precipitation levels than that of S. psammophila. The largest inter-specific difference generally occurred at the 5–10 mm branches during rains of  ≤  2 mm. Precipitation amount was the most influential meteorological characteristic that affected stemflow yield and efficiency in these two endemic shrub species. Branch angle was the most influential plant trait on FR. For SFb, stem biomass and leaf biomass were the most influential plant traits for C. korshinskii and S. psammophila, respectively. For SFP of these two shrub species, leaf traits (the individual leaf area) and branch traits (branch size and biomass allocation pattern) had a great influence during lighter rains  ≤  10 mm and heavier rains  >  15 mm, respectively. The lower precipitation threshold to start stemflow allowed C. korshinskii (0.9 mm vs. 2.1 mm for S. psammophila) to employ more rains to harvest water via stemflow. The beneficial leaf traits (e.g., leaf shape, arrangement, area, amount) might partly explain the greater stemflow production of C. korshinskii. Comparison of SFb between the foliated and manually defoliated shrubs during the 2015 rainy season indicated that the newly exposed branch surface at the defoliated period and the resulting rainfall intercepting effects might be an important mechanism affecting stemflow in the dormant season.


PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7867 ◽  
Author(s):  
Lindsie M. McCabe ◽  
Neil S. Cobb ◽  
Bradley J. Butterfield

Background Bees and flies are the two most dominant pollinator taxa in mountain environments of the Southwest USA. Communities of both taxa change dramatically along elevation gradients. We examined whether bee and fly traits would also change along elevation gradients and if so, do they change in a predictable way related to a decrease in temperature as elevation increases. Methods We used insect body size and darkness traits as proxies for energetic requirements and indicators of cold tolerance in order to assess patterns of bee and fly community trait differences along an elevation gradient. We examined 1,922 individuals of bees and flies sampled along an elevation gradient ranging from 2,400 meters to 3,200 meters and from 9.6 °C to 5.2 °C mean annual temperature. We examined bees and flies separately using community weighted means (site-level trait values weighted by species abundance) and estimates of environmental filtering (quantified as the inverse of the standardized range of trait values). Results Bees and flies exhibited two somewhat distinct patterns; (1) Community weighted mean body volume and darkness of bees increased sharply at the highest elevation, and the intensity of environmental filtering also increased with elevation. This was due to both a change among bee populations within a species as well as species replacement at the highest elevation. (2) Community weighted mean body volume and darkness of flies also increased moderately with increasing elevation, but did not exhibit patterns of significant environmental filtering. In fact, the intensity of environmental filtering as indicated by the range of fly body volume weakened with elevation. Conclusion The increase in filter intensity at high elevations exhibited by bees suggests a significant limitation on the breadth of viable functional strategies for coping with extreme cold, at least within this regional species pool. Flies, on the other hand, do not appear to be limited by high elevations, indicating that the shift from bee to fly dominance at high elevations may be due, at least in part, to greater environmental constraints on bee adaptation to colder environments.


PLoS ONE ◽  
2015 ◽  
Vol 10 (10) ◽  
pp. e0141148 ◽  
Author(s):  
Ilja Sonnemann ◽  
Hans Pfestorf ◽  
Florian Jeltsch ◽  
Susanne Wurst

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 775
Author(s):  
Kathrin Möhrle ◽  
Hugo E. Reyes-Aldana ◽  
Johannes Kollmann ◽  
Leonardo H. Teixeira

Grassland biodiversity is declining due to climatic change, land-use intensification, and establishment of invasive plant species. Excluding or suppressing invasive species is a challenge for grassland management. An example is Jacobaea aquatica, an invasive native plant in wet grasslands of Central Europe, that is causing problems to farmers by being poisonous, overabundant, and fast spreading. This study aimed at testing designed grassland communities in a greenhouse experiment, to determine key drivers of initial J. aquatica suppression, thus dismissing the use of pesticides. We used two base communities (mesic and wet grasslands) with three plant traits (plant height, leaf area, seed mass), that were constrained and diversified based on the invader traits. Native biomass, community-weighted mean trait values, and phylogenetic diversity (PD) were used as explanatory variables to understand variation in invasive biomass. The diversified traits leaf area and seed mass, PD, and native biomass significantly affected the invader. High native biomass permanently suppressed the invader, while functional traits needed time to develop effects; PD effects were significant at the beginning of the experiment but disappeared over time. Due to complexity and temporal effects, community weighted mean traits proved to be moderately successful for increasing invasion resistance of designed grassland communities.


2016 ◽  
Vol 9 (11) ◽  
pp. 4227-4255 ◽  
Author(s):  
Bradley O. Christoffersen ◽  
Manuel Gloor ◽  
Sophie Fauset ◽  
Nikolaos M. Fyllas ◽  
David R. Galbraith ◽  
...  

Abstract. Forest ecosystem models based on heuristic water stress functions poorly predict tropical forest response to drought partly because they do not capture the diversity of hydraulic traits (including variation in tree size) observed in tropical forests. We developed a continuous porous media approach to modeling plant hydraulics in which all parameters of the constitutive equations are biologically interpretable and measurable plant hydraulic traits (e.g., turgor loss point πtlp, bulk elastic modulus ε, hydraulic capacitance Cft, xylem hydraulic conductivity ks,max, water potential at 50 % loss of conductivity for both xylem (P50,x) and stomata (P50,gs), and the leaf : sapwood area ratio Al : As). We embedded this plant hydraulics model within a trait forest simulator (TFS) that models light environments of individual trees and their upper boundary conditions (transpiration), as well as providing a means for parameterizing variation in hydraulic traits among individuals. We synthesized literature and existing databases to parameterize all hydraulic traits as a function of stem and leaf traits, including wood density (WD), leaf mass per area (LMA), and photosynthetic capacity (Amax), and evaluated the coupled model (called TFS v.1-Hydro) predictions, against observed diurnal and seasonal variability in stem and leaf water potential as well as stand-scaled sap flux. Our hydraulic trait synthesis revealed coordination among leaf and xylem hydraulic traits and statistically significant relationships of most hydraulic traits with more easily measured plant traits. Using the most informative empirical trait–trait relationships derived from this synthesis, TFS v.1-Hydro successfully captured individual variation in leaf and stem water potential due to increasing tree size and light environment, with model representation of hydraulic architecture and plant traits exerting primary and secondary controls, respectively, on the fidelity of model predictions. The plant hydraulics model made substantial improvements to simulations of total ecosystem transpiration. Remaining uncertainties and limitations of the trait paradigm for plant hydraulics modeling are highlighted.


Plant Ecology ◽  
2014 ◽  
Vol 215 (11) ◽  
pp. 1351-1359 ◽  
Author(s):  
Simon Pierce ◽  
Arianna Bottinelli ◽  
Ilaria Bassani ◽  
Roberta M. Ceriani ◽  
Bruno E. L. Cerabolini

Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 865
Author(s):  
Zuzana Münzbergová ◽  
Jiří Skuhrovec

Data on plant herbivore damage as well as on herbivore performance have been previously used to identify key plant traits driving plant–herbivore interactions. The extent to which the two approaches lead to similar conclusions remains to be explored. We determined the effect of a free-living leaf-chewing generalist caterpillar, Spodoptera littoralis (Lepidoptera: Noctuidae), on leaf damage of 24 closely related plant species from the Carduoideae subfamily and the effect of these plant species on caterpillar growth. We used a wide range of physical defense leaf traits and leaf nutrient contents as the plant traits. Herbivore performance and leaf damage were affected by similar plant traits. Traits related to higher caterpillar mortality (higher leaf dissection, number, length and toughness of spines and lower trichome density) also led to higher leaf damage. This fits with the fact that each caterpillar was feeding on a single plant and, thus, had to consume more biomass of the less suitable plants to obtain the same amount of nutrients. The key plant traits driving plant–herbivore interactions identified based on data on herbivore performance largely corresponded to the traits identified as important based on data on leaf damage. This suggests that both types of data may be used to identify the key plant traits determining plant–herbivore interactions. It is, however, important to carefully distinguish whether the data on leaf damage were obtained in the field or in a controlled feeding experiment, as the patterns expected in the two environments may go in opposite directions.


2016 ◽  
Vol 64 (1) ◽  
pp. 32 ◽  
Author(s):  
Madalena Vaz Monteiro ◽  
Tijana Blanuša ◽  
Anne Verhoef ◽  
Paul Hadley ◽  
Ross W. F. Cameron

Urban greening solutions such as green roofs help improve residents’ thermal comfort and building insulation. However, not all plants provide the same level of cooling. This is partially due to differences in plant structure and function, including different mechanisms that plants employ to regulate leaf temperature. Ranking of multiple leaf and plant traits involved in the regulation of leaf temperature (and, consequently, plants’ cooling ‘service’) is not well understood. We, therefore, investigated the relative importance of water loss, leaf colour, thickness and extent of pubescence for the regulation of leaf temperature, in the context of species for semi-extensive green roofs. Leaf temperature was measured with an infrared imaging camera in a range of contrasting genotypes within three plant genera (Heuchera, Salvia and Sempervivum). In three glasshouse experiments (each evaluating three or four genotypes of each genus), we varied water availability to the plants and assessed how leaf temperature altered depending on water loss and specific leaf traits. Greatest reductions in leaf temperature were closely associated with higher water loss. Additionally, in non-succulents (Heuchera, Salvia), lighter leaf colour and longer hair length (on pubescent leaves) both contributed to reduced leaf temperature. However, in succulent Sempervivum, colour and pubescence made no significant contribution; leaf thickness and rate of water loss were the key regulating factors. We propose that this can lead to different plant types having significantly different potentials for cooling. We suggest that maintaining transpirational water loss by sustainable irrigation and selecting urban plants with favourable morphological traits are the key to maximising thermal benefits provided by applications such as green roofs.


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