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Whereas temporal variability of plant phenology in response to climate change has already been well studied, the spatial variability of phenology is not well understood. Given that phenological shifts may affect biotic interactions, there is a need to investigate how the variability in environmental factors relates to the spatial variability in herbaceous species' phenology by at the same time considering their functional traits to predict their general and species-specific responses to future climate change. In this project, we analysed phenology records of 148 herbaceous species, which were observed for a single year by the PhenObs network in 15 botanical gardens. For each species, we characterised the spatial variability in six different phenological stages across gardens. We used boosted regression trees to link these variabilities in phenology to the variability in environmental parameters (temperature, latitude and local habitat conditions) as well as species traits (seed mass, vegetative height, specific leaf area and temporal niche) hypothesised to be related to phenology variability. We found that spatial variability in the phenology of herbaceous species was mainly driven by the variability in temperature but also photoperiod was an important driving factor for some phenological stages. In addition, we found that early-flowering and less competitive species characterised by small specific leaf area and vegetative height were more variable in their phenology. Our findings contribute to the field of phenology by showing that besides temperature, photoperiod and functional traits are important to be included when spatial variability of herbaceous species is investigated. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) affects many areas of the world and is increasing globally. To date, there has been limited and inconsistent evidence regarding the consequences of ALAN for plant communities, as well as for the fitness of their constituent species. ALAN could be beneficial for plants as they need light as energy source, but they also need darkness for regeneration and growth. We created model communities composed of 16 plant species sown, exposed to a gradient of ALAN ranging from 'moonlight only' to conditions like situations typically found directly underneath a streetlamp. We measured plant community composition and its production (biomass), as well as functional traits of three plant species from different functional groups (grasses, herbs, legumes) in two separate harvests. We found that biomass was reduced by 33% in the highest ALAN treatment compared to the control, Shannon diversity decreased by 43% and evenness by 34% in the first harvest. Some species failed to establish in the second harvest. Specific leaf area, leaf dry matter content and leaf hairiness responded to ALAN. These responses suggest that plant communities will be sensitive to increasing ALAN, and they flag a need for plant conservation activities that consider impending ALAN scenarios. This article is part of the theme issue 'Light pollution in complex ecological systems'. [ABSTRACT FROM AUTHOR]

Climate, land-use, and invasive plants are among the important drivers of ecosystem functions through the changes in functional composition. In this study, we studied the effects of climate (drought), land-use (Biochar application), and the presence of invasive species on the productivity and performance of invaded experimental grasslands. We ran a greenhouse experiment under controlled conditions, in which we grew a combination of the three native species Silene gallica, Brassica nigra and Phalaris minor and the invasive species Avena fatua, being subjected to four different treatments: Biochar+drought, Biochar, drought, and control. We measured the productivity of native and invasive species as total biomass and root to shoot ratio (RSR) and the performance by measuring several plant functional traits (plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (Nmass), leaf carbon content (Cmass) and total chlorophyll (Chltotal) of all individuals occurring in each plot. The study showed that invasive species were more productive (higher total biomass and lower RSR) and performed better (taller plants, higher SLA, Nmass, Cmass and Chltotal and lower LDMC) than the native species under drought conditions as well as with Biochar application. Accordingly, in contrast to our expectations, the lower productivity and performance of native compared to invasive species under drought were not mitigated by Biochar application. These results provided a deeper understanding of the interplay between climate, land-use, and biological invasion, which is crucial for predicting the consequences of changes in functional composition on ecosystem functions and consequently restoration of grasslands. [ABSTRACT FROM AUTHOR]

Ecosystem functions are heavily dependent on the functional composition of the plant community, i.e., the functional traits of plants forming the community. This, on the one hand, depends on plant occurrence, but on the other hand, depends on the intraspecific variability of functional traits of the species, which are influenced by climate and nutrient availability and affected by plant–plant interactions. To illustrate that, we studied the effects of drought and nitrogen addition (+ N), two important abiotic variables which are changing with ongoing global change, as well as their combined effect on the functional responses of grassland communities in semi‐arid environments of Northern Africa comprising of natural and invasive species. We conducted an experiment where we planted three native species and one invasive plant species in artificial communities of five individuals per species per plot. We exposed these communities to four different treatments: a drought treatment, an N‐addition treatment, the combination between drought and N‐addition, as well as a control. To assess the performance of plants within treatments, we measured selected plant functional traits (plant height, specific leaf area [SLA], leaf dry matter content [LDMC], N content of the leaves [Nmass], specific root length [SRL], and root diameter) for all individuals occurring in our plots, and additionally assessed the above and belowground biomass for each plant individual. We found that the invasive species showed a higher performance (higher biomass accumulation, taller plants, higher SLA, Nmass, SRL, and root diameter as well as lower LDMC) than the native species under drought conditions. The invasive species was especially successful with the combined impact of drought + N, which is a likely scenario in ongoing global change for our research area. Thus, plant functional traits might be a key factor for the invasion success of plant species which will be even more pronounced under ongoing global change. [ABSTRACT FROM AUTHOR]

Leaf senescence is a major event in a plant's life history as autumn marks the end of the growing season. The optimal timing of leaf senescence is crucial to both minimise risks of low temperature events and to maximise carbon gain during the growing season. As abiotic conditions are currently changing at unprecedented rates, it is important to study how leaf senescence of different species is responding to these changes in order to forecast future growing season length and carbon sequestration potentials. In contrast to flowering phenology, data on autumn events are scarce and even more so for herbaceous than for woody plants, thus more information on this phenological stage is urgently needed.We studied leaf senescence in 632 populations from 17 herbaceous species located along elevational gradients. We focussed on the beginning (5% of the population senesce, LS5) and peak (50% senesce, LS50) of leaf senescence. To see whether we can predict species‐specific changes, we studied the link between LS5 and LS50 and flowering phenology as well as leaf functional traits related to plant performance. We looked at first and last flowering day and flowering duration as well as the traits specific leaf area (SLA), leaf dry matter content (LDMC), area‐based leaf nitrogen and carbon content, carbon isotope discrimination (Δ13C) and the stomatal pore area index.We found species‐specific slopes of the beginning of leaf senescence along the elevational gradient. The peak of leaf senescence was uniformly delayed with increasing elevation across all species. Flowering phenology as well as leaf functional traits had a close relationship with leaf senescence and thus can be used to forecast species‐specific responses to changes in abiotic conditions. High SLA and high leaf nitrogen were related to earlier senescence while high LDMC, high Δ13C and high stomatal pore area index were related to later senescence.Synthesis. The link between senescence, flowering phenology and plant functional traits will help to fine‐tune predictions of future growing season length and ecosystem function. To date, most analyses are based on spring phenology and traits, for which data are more abundant than data on autumn senescence. [ABSTRACT FROM AUTHOR]

Frost resistance (FR) is a fundamental process determining various aspects of plant life. Measurements of FR remain challenging as existing methods are time‐ and labour‐intensive.Here, we test the applicability of foliar summer FR measured via the 'electrolyte leakage' approach (FRPEL), a simple and inexpensive technique so far underused in ecological research to estimate FR. We tested the ability of this trait to predict (a) species occurrence, (b) community composition along an elevation gradient and (c) analysed its relationship with nine other traits (SLA, Cmass, Nmass, Pmass, Camass, Mgmass, Kmass, canopy height and the ability to form rosettes) related to plant performance. We studied 183 vascular species occurring at 37 sites, which we also analysed in terms of species composition along an elevation gradient from 656 to 2,363 m a.s.l. in the Bavarian Alps, Germany.Species' FRPEL values correlated significantly with the species occurrence along the elevation gradient. However, this relationship was weak as it explained only 10% in the variation of the Landolt indicator values, a proxy for species geographic ranges. We found a strong positive relationship between community‐weighted FRPEL values and elevation suggesting a strong environmental filtering of this trait that removes species with low FR from the local species pool at high elevations. The community functional diversity of FRPEL significantly increased with increasing elevation suggesting a higher trait divergence in harsher climates. We found significant negative relationships between FRPEL and SLA, canopy height and the ability to form leaf rosettes, indicating a trade‐off in plants between the investment in conservative strategies, in our case FR, and fast resource acquisition.Our study highlights the potential of using FRPEL more frequently in ecological research as we were able to reconfirm three patterns inferred by more precise yet time‐consuming and labour‐intensive approaches. We demonstrate that FRPEL can be used to predict species occurrence and infer assembly rules along elevation gradients. Furthermore, we found that FRPEL is linked to plant functional traits associated with plant performance and morphological features of the plants. However, the trait's predictive power varied greatly among the study objectives and levels. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Highlights • Species-specific variability is the strongest source of trait variability. • Frost resistance and leaf traits of six herbaceous species vary on a temporal scale i.e. during the growth season. • Frost resistance and leaf traits show little variation on a spatial scale, thus temporal variation is stronger. • There is a trade-off between frost resistance and performance, mainly growth rates as assessed via specific leaf area. • Stomatal pore area index is positively related to frost resistance due to differences in leaf thickness. Abstract Frost resistance (FR) is a highly adaptive trait and important for plant performance, survival and distribution. While overall seasonal changes in the frost resistance of herbaceous species are well documented, knowledge of the variability during the growth period is scarce. Responses could be expected due to differences in temperature yet investment in frost resistance might be at the expense of plant performance. To analyse temporal and spatial (i.e. same date but differing temperatures) variability, FR of leaves of six herbaceous species on five sampling dates were assessed along an elevational gradient in the northern limestone Alps. We used chlorophyll fluorescence techniques to calculate the lethal temperature of 90% of the population (LT 90) thereof. To test the association with plant performance, we measured eco-morphological leaf traits (specific leaf area (SLA), leaf dry matter content, leaf phosphorous and magnesium content as well as stomatal pore area index (SPI)) in parallel. We found that FR as well as leaf traits exhibit a strong temporal variation whereas spatial variability was low. When analysing the relationship of FR to leaf traits we found that SLA as a proxy of growth rate was negatively associated with FR indicating a trade-off between growth and resistance, whereas SPI showed a positive relationship to FR. This finding gives further insight into the variability of traits and will help to improve predictions concerning plant performance and distribution under changing climate regimes. [ABSTRACT FROM AUTHOR]

Phenological responses to changing temperatures are known as "fingerprints of climate change," yet these reactions are highly species specific. To assess whether different plant characteristics are related to these species-specific responses in flowering phenology, we observed the first flowering day (FFD) of ten herbaceous species along two elevational gradients, representing temperature gradients. On the same populations, we measured traits being associated with (1) plant performance (specific leaf area), (2) leaf biochemistry (leaf C, N, P, K, and Mg content), and (3) water-use efficiency (stomatal pore area index and stable carbon isotopes concentration). We found that as elevation increased, FFD was delayed for all species with a highly species-specific rate. Populations at higher elevations needed less temperature accumulation to start flowering than populations of the same species at lower elevations. Surprisingly, traits explained a higher proportion of variance in the phenological data than elevation. Earlier flowering was associated with higher water-use efficiency, higher leaf C, and lower leaf P content. In addition to that, the intensity of shifts in FFD was related to leaf N and K. These results propose that traits have a high potential in explaining phenological variations, which even surpassed the effect of temperature changes in our study. Therefore, they have a high potential to be included in future analyses studying the effects of climate change and will help to improve predictions of vegetation changes. [ABSTRACT FROM AUTHOR]

Stomata enable plants to balance uptake of CO 2 with water loss via transpiration. Previous studies have shown that stomatal size and density trade-off with one another and are related to a suite of environmental factors (light, atmospheric CO 2 concentrations, moisture and temperature) which influence gas exchange. We examined the hypothesis that the habitat preferences of species are reflected in stomatal traits. Thus, we examined the relation of stomatal size and density of 36 herbaceous species along elevational gradients in relation to Ellenberg indicator values for light and moisture. The light value is a proxy for the transpiration demand due to exposure to radiation and air mass exchange, the moisture value reflects water supply. Additionally we measured carbon isotope discrimination (Δ 13 C), a proxy for intrinsic water use efficiency and internal CO 2 concentration. Stomatal size changed in parallel on both sides of a leaf, whereas changes in density differed between sides depending on species identity. There was an increase in absolute variation of sizes and densities with increasing mean size and density respectively, but not in relative variation. Species with few but large stomata tended to adjust stomatal size across environmental gradients, whereas species with small but many stomata mainly adjusted stomatal density. A higher Ellenberg indicator value for light and a lower value for moisture was associated with equal distribution of stomata between leaf sides. The carbon isotope discrimination data indicated that amphistomatic species, which illustrated a preference for high radiation and high air mass exchange as well as for dry habitats, had higher water use efficiency. We conclude that stomatal traits such as size, density or the distribution between the two sides of the leaf are indicators of how species optimize carbon uptake and balance water loss and radiation gain. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) is increasing worldwide, but its effects on the soil system have not yet been investigated. We tested the influence of experimental manipulation of ALAN on two taxa of soil communities (microorganisms and soil nematodes) and three aspects of soil functioning (soil basal respiration, soil microbial biomass and carbon use efficiency) over four and a half months in a highly controlled Ecotron facility. We show that during peak plant biomass, increasing ALAN reduced plant biomass and was also associated with decreased soil water content. This further reduced soil respiration under high ALAN at peak plant biomass, but microbial communities maintained stable biomass across different levels of ALAN and times, demonstrating higher microbial carbon use efficiency under high ALAN. While ALAN did not affect microbial community structure, the abundance of plant-feeding nematodes increased and there was homogenization of nematode communities under higher levels of ALAN, indicating that soil communities may be more vulnerable to additional disturbances at high ALAN. In summary, the effects of ALAN reach into the soil system by altering soil communities and ecosystem functions, and these effects are mediated by changes in plant productivity and soil water content at peak plant biomass. This article is part of the theme issue 'Light pollution in complex ecological systems'. [ABSTRACT FROM AUTHOR]

Abstract: Wild mammalian herbivores and cattle are fundamental drivers of African savanna ecosystems and have strong impacts on woody vegetation. However, few experimental studies have investigated the separate and combined influences of different large herbivores on spatial vegetation patterning. In East Africa, temporary cattle corrals (bomas) develop after abandonment into productive, treeless ‘glades’ that attract both domestic and wild herbivores. Edges of glades exhibit unusually high densities of large trees. We used a long-term, broad-scale manipulative experiment to test whether megaherbivores (elephants and giraffes), wild meso-herbivores (15–1000 kg), or cattle caused shifts in woody plant abundances in glade edges. We also examined cascading effects of megaherbivore and cattle exclusion on symbiotic Acacia ants and wild meso-herbivores in glade edges. Megaherbivore exclusion resulted in increased densities of tall trees, reproductive trees, and non-aggressive Acacia ant species in glade edges. Cattle presence reduced meso-herbivore use inside and away from glades, but not in glade edges. Our results suggest that megaherbivores and cattle can dampen the magnitude of spatial patterns associated with glades and glade edges. These findings provide insight into the development and maintenance of spatial heterogeneity in savannas, and emphasize that land use change and mammalian extinctions have complex, cascading ecological consequences. [Copyright &y& Elsevier]

There is a common agreement that, to maximise our understanding of trait‐based community assembly, traits related to different organs should be considered as they relate to different ecological niche axes. Floral traits, in particular, have been suggested to play an important role in the plant community assembly along with environmental gradients as they determine reproductive success, one of the key functions in plants. However, the role of floral traits in community assembly research remains largely unverified empirically.Using a large and novel dataset on plant traits and plant communities, we analysed the variability of six floral traits of 139 herbaceous species in 21 sites located along an elevation gradient (2000–4000 m) in the western Himalayas. The variability of floral traits along the gradient was analysed using community‐weighted mean (CWM) trait values and functional diversities (FDs) calculated for each study community.The CWMs showed that with increasing elevation, flowering began later, and flowers tended to be larger with decreasing specific flower area (SFA). Along with the convergence in the onset of flowering and SFA (i.e. lower FD at high‐elevation sites), these patterns suggest that abiotic filtering and plant–pollinator interactions could affect the floral trait composition of the communities. Most likely, increasing low‐temperature stress towards high‐elevation sites selected for late‐flowering species that produce flowers with larger display areas. The low abundance and activity of pollinators at high elevation could also explain why these traits were selected in the communities studied. Delayed flowering with increasing elevation might facilitate the phenological overlap of plants and their pollinators, as pollinator activity at higher elevation peaks in the second half of the vegetation period. The dominance of a species with low SFA and larger display area in high‐altitude communities could be attributable to increased flower longevity and attraction of pollinators, respectively, to maximise pollination success under pollinator scarcity.Synthesis. Our study provides empirical support for the recent argument that floral traits contribute considerably to the assembly of plant communities along environmental gradients. Thus, such traits should be included in community assembly research as they represent key ecological functions for reproduction. [ABSTRACT FROM AUTHOR]

Summary: Phenology has emerged as key indicator of the biological impacts of climate change, yet the role of functional traits constraining variation in herbaceous species' phenology has received little attention. Botanical gardens are ideal places in which to investigate large numbers of species growing under common climate conditions. We ask whether interspecific variation in plant phenology is influenced by differences in functional traits.We recorded onset, end, duration and intensity of initial growth, leafing out, leaf senescence, flowering and fruiting for 212 species across five botanical gardens in Germany. We measured functional traits, including plant height, absolute and specific leaf area, leaf dry matter content, leaf carbon and nitrogen content and seed mass and accounted for species' relatedness.Closely related species showed greater similarities in timing of phenological events than expected by chance, but species' traits had a high degree of explanatory power, pointing to paramount importance of species' life‐history strategies. Taller plants showed later timing of initial growth, and flowered, fruited and underwent leaf senescence later. Large‐leaved species had shorter flowering and fruiting durations.Taller, large‐leaved species differ in their phenology and are more competitive than smaller, small‐leaved species. We assume climate warming will change plant communities' competitive hierarchies with consequences for biodiversity. [ABSTRACT FROM AUTHOR]

Summary: Land surface phenology (LSP), the characterization of plant phenology with satellite data, is essential for understanding the effects of climate change on ecosystem functions. Considerable LSP variation is observed within local landscapes, and the role of biotic factors in regulating such variation remains underexplored.In this study, we selected four National Ecological Observatory Network terrestrial sites with minor topographic relief to investigate how biotic factors regulate intra‐site LSP variability. We utilized plant functional type (PFT) maps, functional traits, and LSP data to assess the explanatory power of biotic factors for the start and end of season (SOS and EOS) variability.Our results indicate that PFTs alone explain only 0.8–23.4% of intra‐site SOS and EOS variation, whereas including functional traits significantly improves explanatory power, with cross‐validation correlations ranging from 0.50 to 0.85. While functional traits exhibited diverse effects on SOS and EOS across different sites, traits related to competitive ability and productivity were important for explaining both SOS and EOS variation at these sites.These findings reveal that plants exhibit diverse phenological responses to comparable environmental conditions, and functional traits significantly contribute to intra‐site LSP variability, highlighting the importance of intrinsic biotic properties in regulating plant phenology. [ABSTRACT FROM AUTHOR]

Changes in phenology induced by climate change occur across the globe with important implications for ecosystem functioning and services, species performance and trophic interactions. Much of the work on phenology, especially leaf out and flowering, has been conducted on woody plant species. Less is known about the responses in phenology of herbaceous species induced by global change even though they represent a large and important part of biodiversity worldwide. A globally coordinated research effort is needed to understand the drivers and implications of such changes and to predict effects of global change on plant species phenology and related ecosystem processes.Here, we present the rationale of the PhenObs initiative—botanical gardens as a global phenological observation network. The initiative aims to collect data on plant phenology in botanical gardens which will be used alongside information on plant traits and site conditions to answer questions related to the consequences of global change: What is the variation in plant phenology in herbaceous species across the growing season and in response to changes in climate?How can plant phenology be predicted from species' trait composition, provenance, position and extent of the distribution range and species' phylogeny?What are the implications of this variation with respect to species performance and assembly, biotic interactions (e.g. plant–pollinator interactions) as well as ecosystem processes and services under changing land use and climate?Here, we lay out the development of a straightforward protocol that is appropriate for monitoring phenology across a vast diversity of growth forms of herbaceous species from various habitats and geographical regions.To focus on a key number of stages necessary to capture all aspects of plant species phenology, we analysed associations between 14 phenological stages. These data were derived from a 2‐year study on 199 species in four German botanical gardens.Based on the relationships of the phenological stages, we propose to monitor three vegetative stages ('initial growth', 'leaves unfolding' and 'senescence') and two reproductive stages ('flowers open' and 'ripe fruits') to fully capture herbaceous species phenology. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Human activities cause substantial changes in biodiversity. 1,2 Despite ongoing concern about the implications of invertebrate decline, 3,4,5,6,7 few empirical studies have examined the ecosystem consequences of invertebrate biomass loss. Here, we test the responses of six ecosystem services informed by 30 above- and belowground ecosystem variables to three levels of aboveground (i.e., vegetation associated) invertebrate community biomass (100%, 36%, and 0% of ambient biomass) in experimental grassland mesocosms in a controlled Ecotron facility. In line with recent reports on invertebrate biomass loss over the last decade, our 36% biomass treatment also represented a decrease in invertebrate abundance (−70%) and richness (−44%). Moreover, we simulated the pronounced change in invertebrate biomass and turnover in community composition across the season. We found that the loss of invertebrate biomass decreases ecosystem multifunctionality, including two critical ecosystem services, aboveground pest control and belowground decomposition, while harvested plant biomass increases, likely because less energy was channeled up the food chain. Moreover, communities and ecosystem functions become decoupled with a lower biomass of invertebrates. Our study shows that invertebrate loss threatens the integrity of grasslands by decoupling ecosystem processes and decreasing ecosystem-service supply. [Display omitted] • We test the ecosystem consequences of simulated invertebrate decline in an Ecotron • Loss of invertebrate biomass decreases ecosystem multifunctionality • Invertebrate loss reduces aboveground pest control and belowground decomposition • Ecosystem functions become decoupled with a lower biomass of invertebrates Eisenhauer et al. test the ecosystem consequences of invertebrate loss in experimental grassland mesocosms. They find that invertebrate biomass loss decreases ecosystem multifunctionality and coupling, indicating that invertebrate loss threatens the integrity of grasslands by decoupling ecosystem processes and decreasing ecosystem-service supply. [ABSTRACT FROM AUTHOR]

• Greenness biological meaning and its relation with water fluxes are lacking. • New leaves are responsible for the rapid increase in spring canopy greenness. • Canopy greenness can be represented jointly using leaf spectra and leaf age. • Greenness is important to explain variation of canopy conductance. Remote sensing capabilities to monitor evergreen broadleaved vegetation are limited by the low temporal variability in the greenness signal. With canopy greenness computed from digital repeat photography (PhenoCam), we investigated how canopy greenness related to seasonal changes in leaf age and traits as well as variation of trees' water fluxes (characterized by sap flow and canopy conductance). The results showed that sprouting leaves are mainly responsible for the rapid increase in canopy green chromatic coordinate (GCC) in spring. We found statistically significantly differences in leaf traits and spectral properties among leaves of different leaf ages. Specifically, mean GCC of young leaves was 0.385 ± 0.010 (mean ± SD), while for mature and old leaves was 0.369 ± 0.003, and 0.376 ± 0.004, respectively. Thus, the temporal dynamics of canopy GCC can be explained by changes in leaf spectral properties and leaf age. Sap flow and canopy conductance are both well explained by a combination of environmental drivers and greenness (96% and 87% of the variance explained, respectively). In particular, air temperature and vapor pressure deficit (VPD) explained most of sap flow and canopy conductance variance, respectively. Besides, GCC is an important explanatory variable for variation of canopy conductance may because GCC can represent the leaf ontogeny information. We conclude that PhenoCam GCC can be used to identify the leaf flushing for evergreen broadleaved trees, which carries important information about leaf ontogeny and traits. Thus, it can be helpful for better estimating canopy conductance which constraints water fluxes. [ABSTRACT FROM AUTHOR]

Climate change and human-induced stoichiometric imbalances are altering ecosystems across the globe. However, phenology, as the one of first-order control on productivity, has not been well studied with regard to its response to the above environmental changes. With co-located PhenoCams and eddy covariance (EC) towers in a large scale nutrients manipulation experiment (MANIP) in a Mediterranean tree-grass ecosystem, we intend to understand how the structural (i.e. greenness) and physiological phenology (i.e. max gross primary productivity – GPPmax) reacts to the imbalanced availability of nutrients and meteorological changes. Three experimental EC towers are located approximately 500 m apart from each other. Their footprints are manipulated with addition of nitrogen, nitrogen and phosphorus or not fertilized, serving as control. A PhenoCam was installed on the top of each EC tower. GPPmax was derived from EC flux tower measurements and green chromatic coordinates (GCC) was computed from PhenoCams. Then we extracted phenological metrics (i.e. transition dates; slopes and amplitudes of phenological profiles) and their uncertainties from time series of GCC and GPPmax. By comparing the extracted phenological metrics before and after nutrients manipulation, we showed that fertilization increases the speed of green-up and accelerates the senescence of dry-down, which is likely attributed to faster depletion of soil water at fertilized sites due to higher demand of transpiration at dry-down period. By applying statistical models and random forest method, we found meteorological factors like temperature and precipitation are the most important drivers for structural and physiological phenology. The relative importance of the availability of nutrients contributing to phenology is also quantified under different climate change scenarios. We expect that the joint use of proximal remote sensing and EC techniques, in conjunction with models, can help us to better reveal processes of environmental factors mediate the structural and physiological phenology under different nutrient availability. [ABSTRACT FROM AUTHOR]