Decomposing the land-use specific response of plant functional traits along environmental gradients

Land use and water availability drive community-level plant functional diversity of grasslands along a temperature gradient in the Swiss Alps

Functional traits of mountain grassland communities strongly depend upon temperature variation along elevational gradients. However, little is known to what degree the direction of such trait-temperature relationships is shaped by other environmental factors or land-use types. Here, we investigated context-dependent patterns of plant functional trait variation in alpine grassland communities. Specifically, we tested whether temperature (degree-days) variation along an elevational gradient, interacts with water availability, soil properties and land-use type to moderate such patterns. We used cover-abundance and plant-trait data from 236 grassland relevés of the Swiss Alps along an elevational range of 500-2400 m a.s.l. with plant traits being specific leaf area (L), seed releasing height (H) and seed mass (S). We used indices capturing different dimensions of plant functional diversity as response variables, i.e. community weighted mean (CWM), trait range (TR) and functional dispersion (FDis). Land-use type and water availability interacted significantly with degree-days determining the responses of multiple plant traits community attributes. Specific leaf area (CWM_L) and seed releasing height (CWM_H) increased with temperature in meadows and pastures, while no significant trend was detected in fallows. In meadows, seed mass (CWM_S) increased and was at the same time less constrained (higher TR_S) with increasing temperature. In pastures and fallows, by contrast, no seed trait-temperature trends were detected. In addition, water availability interacted with increasing temperature affecting functional dispersion: FDis_L decreased only in sites with higher site water balance and TR_S and FDis_S increased in sites with low mean summer precipitation. Our findings suggest that functional diversity of grasslands might respond to climate warming with strong ecological differences depending on land-use types and water availability. Based on our results, managed meadows and pastures most likely change in direction to species with more acquisitive strategies, whereas in fallows, no specific trajectory of change is expected.

Functional traits of submerged macrophytes in eutrophic shallow lakes affect their ecological functions

Trait-based approaches have been widely used to explore the relationships between submerged macrophytes and their surrounding environments. However, the effects of functional traits on ecological functions of submerged macrophytes in eutrophic lakes are still not well understood. Here, 1745 individuals of eight dominant submerged macrophyte species in 19 Yangtze floodplain lakes were collected and classified as needle-leaf (Myriophyllum spicatum, Ceratophyllum demersum, Stuckenia pectinatus, Najas minor) or flat-leaf (Vallisneria natans, Hydrilla verticillata, Potamogeton wrightii, Potamogeton maackianus) types according to photosynthetic trait-based cluster analysis. The flat-leaf type submerged macrophytes possessed greater photosynthetic (e.g. higher Fv/Fm) and morphological traits (e.g. higher SLA), while the needle-leaf types held greater stoichiometric traits (e.g. higher plant N/P). Moreover, the RDA analysis indicated that water depth (distribution depth of submerged macrophytes) was the key factor influencing functional traits of flat-leaf types, while it was water quality (e.g. WTP and WChl a) for the needle-leaf types. Furthermore, the flat-leaf types showed better performance in improving underwater light conditions (e.g. SD, K_d, Z_eu/WD and Red/Blue) and water quality (e.g. WChl a and TSM). Additionally, distribution depth (WD) of the flat-leaf types was shallower than the needle-leaf types in eutrophic shallow lakes along the middle-lower reaches of the Yangtze River. Our study highlights that functional traits of submerged macrophytes in eutrophic shallow lakes affect their ecological functions.

Species richness and beta diversity patterns of multiple taxa along an elevational gradient in pastured grasslands in the European Alps

To understand how diversity is distributed in space is a fundamental aim for optimizing future species and community conservation. We examined in parallel species richness and beta diversity components of nine taxonomic groups along a finite space, represented by pastured grasslands along an elevational gradient. Beta diversity, which is assumed to bridge local alpha diversity to regional gamma diversity was partitioned into the two components turnover and nestedness and analyzed at two levels: from the lowest elevation to all other elevations, and between neighboring elevations. Species richness of vascular plants, butterflies, beetles, spiders and earthworms showed a hump-shaped relationship with increasing elevation, while it decreased linearly for grasshoppers and ants, but increased for lichens and bryophytes. For most of the groups, turnover increased with increasing elevational distance along the gradient while nestedness decreased. With regard to step-wise beta diversity, rates of turnover or nestedness did not change notably between neighboring steps for the majority of groups. Our results support the assumption that species communities occupying the same habitat significantly change along elevation, however transition seems to happen continuously and is not detectable between neighboring steps. Our findings, rather than delineating levels of major diversity losses, indicate that conservation actions targeting at a preventive protection for species and their environment in mountainous regions require the consideration of entire spatial settings.

Plant palatability and trait responses to experimental warming

Climate warming is expected to significantly affect plant-herbivore interactions. Even though direct effects of temperature on herbivores were extensively studied, indirect effects of temperature (acting via changes in host plant quality) on herbivore performance have rarely been addressed. We conducted multiple-choice feeding experiments with generalist herbivore Schistocerca gregaria feeding on six species of genus Impatiens cultivated at three different temperatures in growth chambers and a common garden. We also studied changes in leaf morphology and chemistry. We tested effects of temperature on plant palatability and assessed whether the effects could be explained by changes in the leaf traits. The leaves of most Impatiens species experienced the highest herbivory when cultivated at the warmest temperature. Traits related to leaf morphology (specific leaf area, leaf dry matter content and leaf area), but not to leaf chemistry, partly mediated the effects of temperature on plant palatability. Herbivores preferred smaller leaves with lower specific leaf area and higher leaf dry matter content. Our study suggests that elevated temperature will lead to changes in leaf traits and increase their palatability. This might further enhance the levels of herbivory under the increased herbivore pressure, which is forecasted as a consequence of climate warming.

Flowering Phenology Shifts in Response to Functional Traits, Growth Form, and Phylogeny of Woody Species in a Desert Area

Climatic factors are considered the major driving forces for variation of flowering phenology among species. Yet, whether flowering phenology of woody species varies with functional traits, growth form, and phylogeny in arid regions is unknown. In the present study, we evaluated the relationships of three characteristics of flowering phenology (i.e., first flowering date, end of flowering date, and flowering duration) against functional traits, growth form, and phylogeny across 59 woody plant species across 3 years in Ürümqi city of the Xinjiang Autonomous Region, in Northwest China. The results showed that, plant functional traits and growth form had significant influences on the variability of flowering phenology among species. The contributions of fruit type (34.7-43.5%) and flower color (30.1-30.7%) to the variability of flowering phenology were larger than those of pollination mode (4.6-14.4%), life form (8.4-14%) and maximum plant height (9.7-13.1%). Trees had the significant correlations in terms of flowering duration against first flowering date and end of flowering date, while shrubs showed the opposite pattern. The values of phylogenetic signal (Blomberg's K) of the three characteristics of flowering phenology ranged from 0.36 to 0.43, which were significantly lower than the expectation of the Brownian motion model. Our results suggested that functional traits, growth form and phylogeny all affected variability of flowering phenology among species. Our results provide a new perspective for correctly evaluating the relationship between global climate change and plant reproduction.

A Methodology for Heterogeneous Sensor Data Organization and Near Real-Time Data Sharing by Adopting OGC SWE Standards

Finding a solution to collect, analyze, and share, in near real-time, data acquired by heterogeneous sensors, such as traffic, air pollution, soil moisture, or weather data, represents a great challenge. This paper describes the solution developed at Eurac Research to automatically upload data, in near real-time, by adopting Open Geospatial Consortium (OGC) Sensor Web Enablement (SWE) standards to guarantee interoperability. We set up a methodology capable of ingesting heterogeneous datasets to automatize observation uploading and sensor registration, with minimum interaction required of the user. This solution has been successfully tested and applied in the Long Term (Socio-)Ecological Research (LT(S)ER) Matsch-Mazia initiative, and the code is accessible under the CC BY 4.0 license.