Related Ecosystem Processes Research Articles

Drivers of contrasting boreal understory vegetation in coniferous and broadleaf deciduous alternative states

AbstractAlternative states defined by tree‐canopy dominance result in different ecosystem functioning and shape habitat conditions for the understory vegetation. One example in the boreal forest is the alternation between broadleaf deciduous and coniferous forests. Disturbances related to natural fires and human land uses have produced changes in tree‐canopy dominance in the boreal region where coniferous forests change to broadleaved forests, affecting understory community dynamics and their related ecosystem processes and functions. To analyze the factors driving changes in understory vegetation and the resistance of its vegetation to shifts between alternative states, we compared the effects of changes in the system between two contrasting boreal forest types (black spruce vs. trembling aspen) in adjacent stands with similar topoedaphic conditions. We performed a 5‐year in situ experiment using alternative states as a theoretical framework including two approaches: (1) the ecosystem approach, manipulating environmental conditions of light, litter, and nutrients in each forest type to determine the main mechanisms associated with tree‐canopy dominance that affect the diversity and composition of understory communities; and (2) the community approach, physically exchanging understory communities between alternative states, to determine their resistance under a new tree‐canopy dominance through time, as well as the resilience of the forest understory after a small‐scale disturbance. Results indicate that the understory vegetation of trembling aspen forests were resistant through time both after changes in local conditions in the ecosystem approach and in the new black spruce‐dominated alternative state in the community approach. In contrast, mosses and ericaceous plants that typically dominate the forest floor of black spruce forests were negatively affected by the physical effect of broadleaf litter addition in our ecosystem approach and they were not resistant when transplanted to trembling aspen forests in the community approach, as they decreased in abundance and were invaded by aspen understory community species over time. The understory vegetation is a key forest ecosystem driver that can contribute to maintain the resilience of the boreal system and help to preserve their ecosystem services, which is a key aspect to consider in forest management faced with the effects of climate change.

Effects of Weak Magnetic Fields on Plant Chemical Composition and Its Ecological Implications

The exposure of plants to weak magnetic fields (MFs) of various intensities and for different times is increasingly adopted to sustainably enhance plant growth in plant-based applications such as modern agriculture, phytoremediation and biogas production. However, little is known about the effects of MF exposure on plant chemical composition, and in turn on related ecosystem processes, such as the transfer of potentially toxic elements along food chains and the decomposition of organic matter. To fill this gap, the present research, through the study of the chemical composition of four edible crops (leaves of lettuce, parsley and basil, and fruits of tomato) differently exposed to weak MFs (75 Hz; 1.5 mT), aimed at evaluating the overall effects of the exposure on ecosystem processes. In particular, several essential (B, C, Ca, Cu, K, Fe, Mg, Mn, Mo, N, Ni, P, S, Zn), beneficial (Co, Na, Se, Si) and non-useful (Al, As, Ba, Cd, Cr, Li, Pb, Sr, Ti, V) elements, together with chemical compounds and derived parameters (soluble sugars, starch, chlorophylls, flavonoids, anthocyanins, nitrogen balance index), indicators of plant metabolism and health, and litter decomposability traits (C/N, C/P), were analyzed. Notwithstanding the expected variations in the observed effects among species and MF exposure conditions, the obtained results highlight a general decrease in most of the studied parameters (with the exception of those related to litter decomposability), attributable to a lower absorption/accumulation of the studied chemical elements and to a reduced synthesis of metabolites. The largest average reduction was observed for the non-useful elements, which outweighs the reduction in essential and beneficial elements and provides for an important MFinduced effect, considering their toxic, persistent and biomagnificable characteristics. Similarly, the induced increases in C/N and C/P ratios indicate the production of litter more recalcitrant to the decomposition process, suggesting that weak MF treatments may be useful to enhance soil C storage and reduce CO2 emissions.

Invasive alien aquatic plant species management drives aquatic ecosystem community recovery: An exploration using stable isotope analysis

The socio-economic and ecological impacts of invasive alien aquatic plant (IAAP) species have been well studied globally. However less is known about ecosystem recovery following the management of IAAP species. This study employed a before-after study design to investigate ecological recovery following the management of Salvinia molesta D.S. Mitchell, at four field sites in South Africa. We hypothesized that the presence of S. molesta would have a negative impact on the ecosystem food web structure, and that following S. molesta control, the systems would show positive ecosystem recovery. Aquatic macroinvertebrate and macrophyte samples collected before and after mechanical or biological control of S. molesta, were analysed for δ13C and δ15N stable isotopes. Salvinia molesta infestations negatively impacted the food web structure, indicated by reduced food chain length, trophic diversity and basal resources. This represented an altered aquatic food web structure, that in some cases, led to the collapse of the aquatic community. In contrast, after either mechanical or biological control, there were increases in food chain length, trophic diversity and abundance of energy resources accessed by consumers, indicating improved food web structure. Although the study showed positive ecosystem recovery following control, we noted that each control method followed a different recovery trajectory. We conclude that S. molesta invasions reduce aquatic biodiversity and alter ecosystem trophic dynamics and related ecosystem processes, necessitating control.

Long‐term hydro‐meteorology and water quality data from low‐gradient catchments of varying scales on the Santee experimental Forest, South Carolina

AbstractThe forest landscape of the Southeastern Atlantic coastal plain of the United States is experiencing increased threats from extreme precipitation events, tropical storms, flooding, droughts, and growing urbanization impacting on vegetation, road infrastructure, water extraction and other related ecosystem processes (e.g., storm runoff, nutrient and carbon cycling) and functions (e.g., flood protection, aquatic habitat). We describe ongoing hydro‐meteorologic monitoring on two first—(1.6 km2 each), the second—(5 km2), and the third—(52.5 km2) order catchments. The catchments are located on the Santee Experimental Forest at the headwaters of the Cooper River that drains into Charleston Harbour, South Carolina. Monitoring started in 1946, with a gap between 1982 and 1989, includes precipitation, weather, streamflow, water table, and water quality (anions, cations, and physical parameters) at varying temporal scales. The catchments are forest ecosystems dominated by loblolly (Pinus taeda) and longleaf pine (Pinus palustris) (LLP) mixed hardwood stands on the uplands and bottomland hardwoods on well‐drained to poorly‐drained soils characteristic of the low‐gradient Atlantic Coastal Plain. These data support multiple field and modelling studies, ranging from water and carbon budgets to hydrologic and biogeochemical processes to effects of microtopography and extreme climate on hydrology and water quality of these coastal catchments withstands regenerated since Hurricane Hugo (1989). One significant finding from the long‐term data was a reversal of the pre‐Hugo flow pattern between the paired watersheds 3 years after Hugo. This reversal persisted for 10 years and was attributed to change in forest vegetation due to hurricane damage to older pine and larger hardwood stands followed by delayed regeneration before full forest recovery. These publicly available data serve as a reference within a rapidly developing landscape and also for addressing potential impacts of extreme climate and forest disturbance on ecohydrology, biogeochemistry, habitat, water supply and infrastructure using validated models and tools.

The PhenObs initiative: A standardised protocol for monitoring phenological responses to climate change using herbaceous plant species in botanical gardens

Abstract 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.

Urbanization and plant invasion alter the structure of litter microarthropod communities.

Anthropogenic activity underpins the creation of urban ecosystems, often with introduced or invasive species playing a large role in structuring ecological communities. While the effects of urbanization on charismatic taxa such as birds, bees or butterflies have received much attention, the impacts on small and inconspicuous organisms remain poorly understood. Here, we assess how the community structure of leaf litter-inhabiting microarthropods in city parks varies along an urbanization gradient in Toronto, Canada. At each park, we established paired forest understorey plots which were either dominated by native vegetation or dog-strangling vine Vincetoxicum rossicum, an invasive species that is spreading throughout northeastern North America and abundant in urban areas. We compared microarthropod richness, abundance and diversity in ecological traits between invaded and non-invaded plots as well as compositional dissimilarities among plots across the urbanization gradient. We recorded 123 genera and found (a) there was a negative effect of urbanization on microarthropod richness and abundance but only in invaded plots; (b) richness and abundance increased continuously with urbanization in non-invaded plots, but peaked at intermediate urbanization levels in invaded plots and (c) there was significant turnover with increasing urbanization, with distinct communities represented in highly urbanized areas compared to less urbanized areas, regardless of whether invaded. We also found litter microarthropod richness and abundance increased with soil ammonium and decreased with nitrate. These trends were especially strong for fungivorous microarthropods; however, there was no relationship between soil nutrients and urbanization or invasion. Urbanization and biological invasion drive biodiversity change, and there is a need to disentangle these effects on ecological communities and related ecosystem processes. We show microarthropod communities change with urbanization, with the effects of invasion most prominent in non-urban areas. Here, there is high richness and abundance but low ecological trait diversity, possibly because certain feeding traits are excluded and others overrepresented. Understanding of urban ecological systems must include knowledge of the microarthropods that interact widely across food webs, form distinct communities in highly urban areas and drive many of the important ecological functions upon which people in cities depend.

Soil protist communities in burrowing and casting hotspots of different earthworm species

Biotic interactions in the soil food web have been increasingly recognized as crucial for ecosystem functioning, however there are still knowledge gaps in terms of the associations between macrofauna and microorganisms, particularly in soil hotspot microsites. A manipulative study was performed to investigate the protist community in the drilosphere and casts of three earthworm species (epigeic Amynthas cortices, anecic Amynthas hupeiensis and endogeic Drawida gisti) and a control soil without earthworms. Results showed that earthworm presence significantly increased the relative abundance of parasitic protists (p < 0.05). The diversity of protists within drilosphere and casts depended on earthworm species, with D. gisti and A. hupeiensis increasing diversity and A. cortices decreasing protist diversity (p < 0.05). Structural equation modelling indicated that protist abundance and diversity in the drilosphere were regulated indirectly via neutralized soil pH and accelerated C and N mineralization, while in casts were affected directly through earthworm gut processing and indirectly through elevated water content. In conclusion, the marked effects on soil protist community mediated by earthworms varied from distinct earthworm species and microsites. The present study suggests the necessity to consider interactions between protist and earthworms in evaluating the effects of soil fauna on soil biota and the related ecosystem processes.

Modelling inter‐annual and spatial variability of ice cover in a temperate lake with complex morphology

AbstractThe formation of ice cover on lakes alters heat and energy transfer with the water column. The fraction of surface area covered by ice and the timing of ice‐on and ice‐off therefore affects hydrodynamics and the seasonal development of stratification and related ecosystem processes. Multi‐year model simulations of temperate lake ecosystems that freeze partially or completely therefore require simulation of the formation and duration of ice cover. Here we present a multi‐year hydrodynamic simulation of an alpine lake with complex morphology (Lower Lake Constance, LLC) using the three‐dimensional (3D) model Aquatic Ecosystem Model (AEM3D) over a period of 9 years. LLC is subdivided into three basins (Gnadensee, Zeller See and Rheinsee) which differ in depth, morphological features, hydrodynamic conditions and ice cover phenology and thickness. Model results were validated with field observations and additional information on ice cover derived from a citizen science approach using information from social media. The model reproduced the occurrence of thin ice as well as its inter‐annual variability and differentiated the frequency and extent of ice cover between the three sub‐basins. It captured that full ice cover occurs almost each winter in Gnadensee, but only rarely in Zeller See and Rheinsee. The results indicate that the 3D model AEM3D is suitable for simulating long‐term dynamics of thin ice cover in lakes with complex morphology and inter‐annual changes in spatially heterogeneous ice cover.

Mixing effect of polylactic acid microplastic and straw residue on soil property and ecological function.

Microplastics have become a contaminant of increasing concern in soils. Although biodegradable plastics were considered as alternatives of traditional plastics, some evidence showed that biodegradable plastics might produce more microplastics. Until now, the effect of biodegradable microplastics on soil functions and processes, as well as microbial communities is uncertain. Based on high throughput sequencing, enzymatic activity assay and dynamic analysis of soil carbon and nitrogen, we investigated the effects of biodegradable polylactic acid microplastics (PLA MPs) on soil microbiota and related ecological processes under conditions of high or low carbon content. The results showed that PLA MPs had no significant effect on the overall diversity and composition of bacterial communities or related ecosystem functions and processes. However, co-occurrence network analysis revealed that PLA MPs impacted the interactions between constituent species, which might have legacy effect on soil bacterial communities and functions. Our data also revealed that PLA MPs could trade off the priming effect of carbon source. Our results provided an integrated picture in understanding the effects of PLA MPs on soil microbes, properties and ecological functions, which will help to further understand the effects of MPs on terrestrial ecosystems.

Multiple stressor effects on biodiversity and ecosystem functioning in a Mediterranean temporary river

The hydrological and biological complexity of temporary rivers as well as their importance in providing goods and services is increasingly recognized, as much as it is the vulnerability of the biotic communities in view of climate change and increased anthropogenic pressures. However, the effects of flow intermittency (resulting from both seasonal variations and rising hydrological pressure) and pollution on biodiversity and ecosystem functioning have been overlooked in these ecosystems. We explore the way multiple stressors affect biodiversity and ecosystem functioning, as well as the biodiversity-ecosystem functioning (B-EF) relationship in a Mediterranean temporary river. We measured diversity of benthic communities (i.e. diatoms and macroinvertebrates) and related ecosystem processes (i.e. resource use efficiency-RUE and organic matter breakdown-OMB) across a pollution and flow intermittency gradient. Our results showed decreases in macroinvertebrate diversity and the opposite trend in diatom assemblages, whereas ecosystem functioning was negatively affected by both pollution and flow intermittency. The explored B-EF relationships showed contrasting results: RUE decreased with higher diatom diversity, whereas OMB increased with increased macroinvertebrate diversity. The different responses suggest contrasting operating mechanisms, selection effects possibly driving the B-EF relationship in diatoms and complementarity effects driving the B-EF relationship in macroinvertebrates. The understanding of multiple stressor effects on diversity and ecosystem functioning, as well as the B-EF relationship in temporary rivers could provide insights on the risks affecting ecosystem functioning under global change.

Increasing N deposition impacts neither diversity nor functions of deadwood-inhabiting fungal communities, but adaptation and functional redundancy ensure ecosystem function.

Nitrogen deposition can strongly affect biodiversity, but its specific effects on terrestrial microbial communities and their roles for ecosystem functions and processes are still unclear. Here, we investigated the impacts of N deposition on wood-inhabiting fungi (WIF) and their related ecological functions and processes in a highly N-limited deadwood habitat. Based on high-throughput sequencing, enzymatic activity assay and measurements of wood decomposition rates, we show that N addition has no significant effect on the overall WIF community composition or on related ecosystem functions and processes in this habitat. Nevertheless, we detected several switches in presence/absence (gain/loss) of wood-inhabiting fungal OTUs due to the effect of N addition. The responses of WIF differed from previous studies carried out with fungi living in soil and leaf-litter, which represent less N-limited fungal habitats. Our results suggest that adaptation at different levels of organization and functional redundancy may explain this buffered response and the resistant microbial-mediated ecosystem function and processes against N deposition in highly N-limited habitats.

Can wetland plant functional groups be spectrally discriminated?

Plant functional traits (PFTs) underpin ecosystem processes and therefore ecosystem service provision. If PFTs are possible to detect and discriminate spectrally, then it may be possible to use remote sensing applications to map ecosystem processes or services within and across landscapes. As a first step towards this application, we explored whether functional groups of 22 dominant South African wetland species were spectrally separable based on their PFTs. We measured 23 biochemical and morphological PFTs in combination with spectra from 350 to 2349 nm using a handheld radiometer. First, we evaluated the possibility of accurately predicting morphological and biochemical PFTs from reflectance spectra using three approaches: spectrum averaging, redundancy analysis (RDA), and partial least squares regression (PLSR). Second, we established whether functional groups and species were spectrally distinguishable. We found seven PFTs to be important in at least two of the three approaches: four morphological and three biochemicals. Morphological traits that were important were leaf area (PLSR: r2 = 0.40, regression: r2 = 0.41), specific leaf area (r2 = 0.67), leaf mass (r2 = 0.43, r2 = 0.38), and leaf length/width ratio (r2 = 0.62). Biochemical traits that play a role in the structural composition of vegetation, like lignin content (r2 = 0.98, r2 = 0.54), concentration (r2 = 0.45) and cellulose content (r2 = 0.57, r2 = 0.49), were found to be important by at least two of the analyses. Three other traits were important in at least one of the analyses: total biomass (r2 = 0.56), leaf C/N ratio (r2 = 0.99), and cellulose concentration (r2 = 0.76). Redundancy analysis suggests that there is a large percentage (52%) of the spectrum not explained by the PFTs measured in this study. However, spectral discrimination of functional groups, and even species, appears promising, mostly in the ultraviolet A part of the spectrum. This has interesting applications for mapping PFTs using remote sensing techniques, and therefore for estimating related ecosystem processes and services.

Disappearing giants: a review of threats to freshwater megafauna

Charismatic megafauna species may act as both flagship and umbrella species. They influence local environments and biotas, determine related ecosystem processes and functions, and are associated with high levels of biodiversity. However, the intrinsic characteristics of megafauna species including long lifespan, large body size, sparseness and/or rarity, late maturity, and low fecundity, as well as high market value, make them very prone to extinction. Up to now, scientific interest and conservation efforts have mainly focused on terrestrial and marine megafauna, while freshwater species have received comparatively little attention, despite evidence suggesting that freshwaters are losing species faster than marine or terrestrial realms. The high susceptibility of freshwater megafauna to multiple threats, coupled with immense human pressure on freshwater ecosystems, places freshwater megafauna amongst the most threatened species globally. The main threats include overexploitation, dam construction, habitat degradation, pollution, and species invasion. These threats increase mortality, decrease productivity, and reduce fitness, causing the decline of populations and the extinction of freshwater megafauna species. Given the essential ecological and biological roles of freshwater megafauna, further research should focus on their distribution patterns, extinction risks, and population dynamics, thereby improving the knowledge base for conservation planning. Finally, freshwater megafauna‐based conservation strategies may raise public awareness for freshwater conservation and therefore benefit a broader range of freshwater species and functions. WIREs Water 2017, 4:e1208. doi: 10.1002/wat2.1208This article is categorized under: Water and Life &gt; Conservation, Management, and Awareness Water and Life &gt; Nature of Freshwater Ecosystems Water and Life &gt; Stresses and Pressures on Ecosystems

Functional trait variation and nitrogen use efficiency in temperate coastal phytoplankton

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 563:35-49 (2017) - DOI: https://doi.org/10.3354/meps11974 Functional trait variation and nitrogen use efficiency in temperate coastal phytoplankton Elsa Breton, Urania Christaki, Simon Bonato, Morgane Didry, Luis Felipe Artigas* UMR 8187 LOG, Laboratoire d’Océanologie et de Géosciences, Université du Littoral Côte d’Opale, CNRS, Université Lille, 62930 Wimereux, France *Corresponding author: felipe.artigas@univ-littoral.fr ABSTRACT: This study explored the relevance of the use of a trait-based approach to explain seasonal phytoplankton succession and the underlying mechanisms that structure phytoplankton assemblages and promote nitrogen use efficiency (NUE) in the temperate coastal waters of the eastern English Channel (EEC). A 3 yr time series of phytoplankton abundance assessed by flow cytometry was combined with a selection of traits related to resource utilization (light and inorganic nutrients), grazing resistance, and maximum growth, mainly sourced from the literature. Our results showed that the identified functional groups (FGs) ranged deterministically along a temporal gradient of light and nutrient availability, according to several fundamental trade-offs. These trade-offs, which reflected different ecological strategies, were distributed along 1 axis of niche differentiation. This favoured different FGs through time, and consequently allowed them to partition those available resources. The observed functional divergence of the phytoplankton community deviated from that of the expected, random one. It showed that as light increased, the phytoplankton community assembly was mainly driven by competition and grazing pressure, which eventually favoured those FGs that were fastest growing and less vulnerable to predation. Structural equation modeling evidenced that a phytoplankton community, functionally dominated by FGs that were relatively large, fast-growing, and well-adapted to higher light, promoted NUE. Together, these results confirmed the potential use of laboratory-measured functional traits to explore environment-trait linkages in phytoplankton. They also showed the possibility of further extending this approach to identify the mechanisms driving phytoplankton community assembly, structure, and related ecosystem processes. KEY WORDS: Phytoplankton community · Flow cytometry · Functional traits · Nitrogen use efficiency Full text in pdf format Supplementary material PreviousNextCite this article as: Breton E, Christaki U, Bonato S, Didry M, Artigas LF (2017) Functional trait variation and nitrogen use efficiency in temperate coastal phytoplankton. Mar Ecol Prog Ser 563:35-49. https://doi.org/10.3354/meps11974 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 563. Online publication date: January 20, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Time lags in functional response to management regimes - evidence from a 26-year field experiment in wet meadows

Questions (i) How does functional composition and diversity respond to different timings and frequencies of mowing or fallow treatment? (ii) To which species assembly and related ecosystem processes do these developments correspond? (iii) What is the time course of these developments, and do they reach a stable state? Location North-western Germany Methods In 1987, a field experiment in nine wet meadow sites formerly exploited as fertilized meadows or pastures was established with four management treatments: (i) mowing twice a year in June/July and in September, (ii) mowing once a year in June/July, (iii) mowing once a year in September, and (iv) leaving fallow except shrub removal. Vegetation was recorded at least every second year and the functional composition (community weighted means) and diversity (Rao's quadratic entropy) were analysed in the course of the experiment. We selected eight plant functional traits (Canopy height, SLA, LDMC, Seed mass, Shoot cyclicity, Clonal Index, Onset of flowering, Leaf distribution) capturing the main plant life strategies. Results Temporal changes, fluctuations and divergences between treatments could be observed in both functional composition and diversity. In particular, the vegetation of the fallow treatment showed strong competition for light and a higher investment into internal nutrient cycling. Over time, all treatments respond towards more stressful conditions due to generally less intensive management compared with the former management and respective nutrient depletion, leading to a more nutrient retentive and patch holding strategy and little investment into competitive seedlings. High competition and loose abiotic filters in the fallow treatment led to a niche separation in foliar traits. Mowing on the other hand enforced a divergence of reproduction mechanisms. Conclusion We detected long-term fluctuations and ongoing changes in functional composition and diversity even after 26 years. Especially early succession was characterized by a transient loss of functional diversity, caused by strong time lags in immigration and extinction of species. Our findings stress the importance of long-term experimental studies to avoid precarious misinterpretations. This article is protected by copyright. All rights reserved.

Importance of riparian habitat for frugivorous bats in a tropical dry forest in western Mexico

Abstract:Riparian forests (RF) provide shelter, feeding resources and commuting areas and are fundamental for local fauna during long drought periods in tropical dry forests. Nevertheless, information regarding vertebrate ecology in tropical RF is scarce. The studies of bats in riparian habitats have been mostly focused on insectivorous assemblages in non-tropical regions. We contrasted the occurrence of frugivorous bats between RF and upland dry forest (UDF) in a Neotropical dry forest region and evaluated how vegetation structure modulates frugivorous bat presence and abundance. We sampled bat ensembles and vegetation structure in three UDF and three RF sites in Jalisco, Mexico. Bat ensembles and populations were analysed with generalized linear models, including as independent factors: (1) habitat and (2) vegetation attributes. In 72 nights we captured 840 bats belonging to seven species. No effect of habitat type or vegetation structure on species richness was found, but habitat type did affect bat species composition and abundance. Moreover, vegetation structural traits affected frugivorous bat abundance. Frugivore abundance was higher in RF than in UDF probably because RF provides greater resources and more roosting sites. Riparian forests also present more canopy cover and accessible flight spaces. Our results support the importance of RF for frugivorous bats in terms of abundance and composition. Additionally, the lack of differences in species richness between UDF and RF highlights the importance of both habitats for maintaining frugivorous bats, as well as the related ecosystem processes and services in tropical dry forest landscapes.

Interlinking climate change with water-energy-food nexus and related ecosystem processes in California case studies

Global climate change creates critical challenges with increasing temperature, reducing snowpack, and changing precipitation for water, energy, and food, as well as ecosystem processes at regional scales. Ecosystem services provide life support, goods, and natural resources from water, energy, and food, as well as the environments. There are knowledge gaps from the lack of conceptual framework and practices to interlink major climate change drivers of water resources with water-energy-food nexus and related ecosystem processes. This paper provided an overview of research background, developed a conceptual framework to bridge these knowledge gaps, summarized California case studies for practices in cross sector ecosystem services, and identified future research needs. In this conceptual framework, climate change drivers of changing temperature, snowpack, and precipitation are interlinked with life cycles in water, energy, food, and related key elements in ecosystem processes. Case studies in California indicated climate change affected variation in increasing temperature and changing hydrology at the regional scales. A large variation in average energy intensity values was also estimated from ground water and federal, state, and local water supplies both within each hydrological region and among the ten hydrological regions in California. The increased regional temperature, changes in snowpack and precipitation, and increased water stresses from drought can reduce ecosystem services and affect the water and energy nexus and agricultural food production, as well as fish and wildlife habitats in the Sacramento-San Joaquin Delta (Delta) and Central Valley watersheds. Regional decisions and practices in integrated management of water, energy, food, and related ecosystem processes are essential to adapt and mitigate global climate change impacts at the regional scales. Science and policy support for interdisciplinary research are critical to develop the database and tools for comprehensive analysis to fill knowledge gaps and address ecosystem service complexity, the related natural resource investment, and integrated planning needs.

Secondary bacterial symbiont community in aphids responds to plant diversity.

Biodiversity is important for ecosystem functioning and biotic interactions. In experimental grasslands, increasing plant species richness is known to increase the diversity of associated herbivores and their predators. If these interactions can also involve endosymbionts that reside within a plant or animal hostis currently unknown. In plant-feeding aphids, secondary bacterial symbionts can have strong fitness effects on the host, e.g. resistance to natural enemies or fungal pathogens. We examined the secondary symbiont community in three species of aphid, each feeding on a unique host plant across experimental plots that varied in plant species richness. Aphids were collected in May and June, and the symbiont community identified using species-specific PCR assays. Aphis fabae aphids were found to host six different symbiont species with individual aphids co-hosting up to four symbionts. Uroleucon jaceae and Macrosiphum rosae hosted two and three symbiont species, respectively. We found that, at the aphid population level, increasing plant species richness increased the diversity of the aphid symbiont community, whereas at the individual aphid level, the opposite was found. These effects are potentially driven by varying selective pressures across different plant communities of varying diversities, mediated by defensive protection responses and a changing cost-benefit trade-off to the aphid for hosting multiple secondary symbionts. Our work extends documented effects of plant diversity beyond visible biotic interactions to changes in endosymbiont communities, with potentially far-reaching consequences to related ecosystem processes.

Cross‐scale impact of climate temporal variability on ecosystem water and carbon fluxes

AbstractWhile the importance of ecosystem functioning is undisputed in the context of climate change and Earth system modeling, the role of short‐scale temporal variability of hydrometeorological forcing (~1 h) on the related ecosystem processes remains to be fully understood. Various impacts of meteorological forcing variability on water and carbon fluxes across a range of scales are explored here using numerical simulations. Synthetic meteorological drivers that highlight dynamic features of the short temporal scale in series of precipitation, temperature, and radiation are constructed. These drivers force a mechanistic ecohydrological model that propagates information content into the dynamics of water and carbon fluxes for an ensemble of representative ecosystems. The focus of the analysis is on a cross‐scale effect of the short‐scale forcing variability on the modeled evapotranspiration and ecosystem carbon assimilation. Interannual variability of water and carbon fluxes is emphasized in the analysis. The main study inferences are summarized as follows: (a) short‐scale variability of meteorological input does affect water and carbon fluxes across a wide range of time scales, spanning from the hourly to the annual and longer scales; (b) different ecosystems respond to the various characteristics of the short‐scale variability of the climate forcing in various ways, depending on dominant factors limiting system productivity; (c) whenever short‐scale variability of meteorological forcing influences primarily fast processes such as photosynthesis, its impact on the slow‐scale variability of water and carbon fluxes is small; and (d) whenever short‐scale variability of the meteorological forcing impacts slow processes such as movement and storage of water in the soil, the effects of the variability can propagate to annual and longer time scales.

Dust effects on snowpack melt and related ecosystem processes are secondary to those of forest canopy structure and interannual snowpack variability

AbstractDust deposition lowers the albedo of snow and can significantly alter snowpack energy balance. Investigation of aeolian dust deposition in the mountains of the western U.S. has shown that these effects advance the timing of snowpack melt and spring runoff across much of the region. These studies have primarily focused on alpine snowpacks with little to no overstory vegetation. To evaluate the impacts of aeolian dust on ecohydrological processes in forests, we conducted a manipulative experiment in a subalpine conifer forest in Utah's Wasatch Mountains. During the spring of 2010–2012, we added dust to the snow surface in forested plots every 1 to 2 weeks, roughly doubling the natural dust loading. We then measured snowpack ablation in control and dust addition plots, along with below‐snowpack and warm season soil temperature (Tsoil), soil water content (θ), litter decomposition rate (D), soil respiration rate (Rs), and tree xylem water potential (ψ). Differences in ablation between control and dust addition plots were similar in magnitude to differences associated with the canopy structure of the forest. Seasonal patterns in Tsoil and θ were similar between dust treatments and canopy structure groups. D, Rs, and ψ varied little between dust treatments, but there were significant differences between years. During our 3‐year study, an unusual level of interannual variability in snowfall had the greatest effect on the soil environment and ecosystem processes. The effects of aeolian dust on snowpack mass and energy balance in our forest were slightly smaller than those associated with canopy structure. Copyright © 2014 John Wiley &amp; Sons, Ltd.