Changes In Ecosystem Properties Research Articles

Foundation species stabilize an alternative eutrophic state in nutrient-disturbed ponds via selection on microbial community.

Eutrophication due to nutrient addition can result in major alterations in aquatic ecosystem productivity. Foundation species, individually and interactively, whether present as invasive species or as instruments of ecosystem management and restoration, can have unwanted effects like stabilizing turbid eutrophic states. In this study, we used whole-pond experimental manipulations to investigate the impacts of disturbance by nutrient additions in the presence and absence of two foundation species: Dreissena polymorpha (a freshwater mussel) and Myriophyllum spicatum (a macrophyte). We tracked how nutrient additions to ponds changed the prokaryotic and eukaryotic communities, using 16S, 18S, and COI amplicon sequencing. The nutrient disturbance and foundation species imposed strong selection on the prokaryotic communities, but not on the microbial eukaryotic communities. The prokaryotic communities changed increasingly over time as the nutrient disturbance intensified. Post-disturbance, the foundation species stabilized the prokaryotic communities as observed by the reduced rate of change in community composition. Our analysis suggests that prokaryotic community change contributed both directly and indirectly to major changes in ecosystem properties, including pH and dissolved oxygen. Our work shows that nutrient disturbance and foundation species strongly affect the prokaryotic community composition and stability, and that the presence of foundation species can, in some cases, promote the emergence and persistence of a turbid eutrophic ecosystem state.

Short-term impacts of wildfire and post-fire mulching on ecosystem multifunctionality in a semi-arid pine forest

Straw and wood chips have been widely used as mulch materials to control post-fire erosion in burned forests. However, their effects on ecosystem multifunctionality (EMF) have been little explored. This information is essential to give forest managers insight about the effectiveness of these strategies for restoration of severely-burned forests. To fill this gap, this study has evaluated the short-term (one year after wildfire) changes in ecosystem properties (associated to soil characteristics), structure (linked to plant diversity), individual ecosystem functions, and EMF in a Mediterranean forest. This delicate ecosystem was burned by a wildfire and then mulched with straw or wood chips, and EMF in these conditions was compared to burned and untreated, and unburned sites. The results have shown that: (i) neither wildfire nor mulching significantly changed soil properties with the exception of pH; (ii) in contrast, ecosystem structure significantly declined in mulched plots due to wildfire, and mulching did not limit the alteration in species richness; (iii) among the analysed ecosystem functions, waste decomposition and nutrient cycling, which were significantly higher in unburned soils compared to burned sites, showed intermediate and similar values in mulched plots, while water cycle and wood production (the latter with the exception of unburned plots) were similar among all soil conditions, and climate regulation was significantly higher only in soils mulched with wood chips compared to burned sites; (iv) EMF increased from burned and untreated soils to unburned sites; (v) mulching was effective at limiting the reduction in EMF due to wildfire, but only partially dampened the impact of the fire. Moreover, the combined analysis of ecosystem properties, structure and functions, and EMF revealed that: (i) all functions, except water cycle, were associated to one or more soil or vegetation parameters; (ii) species community composition noticeably influenced several ecosystem functions, and, therefore, EMF; (iii) species richness is a key driver of wood production; (iv) pH, which was found as the most influential soil property on ecosystem functions and EMF, may be considered as an important ecological predictor of forest functions in basic soils of Mediterranean forests. This study may be of practical importance for policymakers and land managers about the most effective actions to preserve the ecosystem EMF in fragile ecosystems, such as the Mediterranean wildfire-affected forest.

How do multidimensional traits of dominant diatom Aulacoseira respond to abiotic and biotic factors in a river delta system?

Trait-based approaches are being increasingly applied in ecology, and the influence of individual-level trait variation on communities and species has been demonstrated. However, the responses of individual trait variation to environmental changes remain to be explored. To examine the indicating functions of multidimensional traits, individual-level measurements of the dominant diatom genus Aulacoseira Thwaites in the Pearl River Delta were performed, and corresponding responses of three trait indices (trait richness, trait evenness, and trait dispersion) to abiotic and biotic factors were examined. Our results indicated that the three individual trait diversity indices were regulated by different factors. Trait richness was only significantly affected by abiotic factors (temperature), while trait evenness and trait dispersion were regulated by both abiotic and biotic factors. In addition, the direct influence of abiotic factors was more significant than that of biotic factors, implying that the multidimensional trait variation of Aulacoseira was more responsive to environmental changes than to interspecific interactions. Therefore, the multidimensional trait variation of Aulacoseira could be used as an effective indicator to track environmental changes. Our study elucidated the mechanisms relating individual-level trait variation to phytoplankton community dynamics; this could improve our ability to forecast changes in ecosystem properties across environmental gradients.

Do predators have a role to play in wetland ecosystem functioning? An experimental study in New England salt marshes.

The historical ecological paradigm of wetland ecosystems emphasized the role of physical or “bottom‐up” factors in maintaining functions and services. However, recent studies have shown that the loss of predators in coastal salt marshes can lead to a significant reduction in wetland extent due to overgrazing of vegetation by herbivores. Such studies indicate that consumers or “top‐down” factors may play a much larger role in the maintenance of wetland ecosystems than was previously thought. The objective of this study was to evaluate whether altering top‐down control by manipulating the presence of predators can lead to measurable changes in salt marsh ecosystem properties. Between May and August of 2015 and 2016, we established exclosure and enclosure cages within three New England coastal wetland areas and manipulated the presence of green crab predators to assess how they and their fiddler and purple marsh crab prey affect changes in ecosystem properties. Predator presence was associated with changes in soil nitrogen and aboveground biomass at two of the three field sites, though the magnitude and direction of these effects varied from site to site. Further, path analysis results indicate that across field sites, a combination of bottom‐up and top‐down factors influenced changes in measured variables. These results challenge the growing consensus that consumers have strong effects, indicating instead that predator impacts may be highly context‐dependent.

The resilience of coastal ecosystems: A functional trait‐based perspective

Abstract Coastal ecosystems provide important services to human population, such as nurseries for fish, carbon storage and coastal protection. However, the pressure faced by these systems due to global changes will strongly challenge the capacity of coastal ecosystems to persist. Therefore, it is crucial to understand the resilience of coastal ecosystems. Here, I propose that combining a resilience framework based on ecosystem properties with the functional trait response–effect framework would allow researchers and managers to quantify the resilience of coastal ecosystems. I place emphasis on salt marsh and sand dunes because of the higher availability of studies for these systems. First, I introduce the resilience framework based on ecosystem properties and, second, I show how adopting a functional trait perspective in this framework would allow researchers to link how environmental changes influence ecosystem properties. In turn, measuring the changes in ecosystem properties would allow researchers to measure the resilience of the system. Synthesis. I reviewed several types of disturbances (e.g. storms and sea‐level rise) that are threatening the persistence of coastal ecosystems, with an emphasis on salt marshes and sand dunes. Applying this resilience framework reveals, for instance, that the same suite of traits (e.g. plant density and stiffness) increase marsh resistance to multiple threats (e.g. storms and sea‐level rise); yet, these traits vary along environmental gradients (e.g. along estuaries) and, therefore, the resilience of marshes vary accordingly. Overall, this framework would allow researchers to gather crucial insights on the resilience of coastal ecosystems and to set reference marks for measuring their resilience under environmental changes.

Impact of Ocean Acidification on Ecosystem Functioning and Services in Habitat-Forming Species and Marine Ecosystems

Ocean acidification (OA) is expected to impact habitat-forming species (HFS), with cascading effects on the whole marine ecosystem and related services that are seldom quantified. Here, the changes in HFSs biomass due to OA are modeled using a food web ecosystem model, and the trophic and non-trophic cascading effects on the marine community are investigated. The food web model represents a well-studied coastal marine protected area in the NW Mediterranean Sea where coralligenous reefs and Posidonia oceanica meadows constitute important HFS. The model is used to implement 5 scenarios of habitat degradation, that is, reduction of HFS biomass, induced by increasing OA and to quantify the potential changes in ecosystem properties and indicators of ecosystem services over the next 100 years. The changes in ecosystem indicators highlight a decrease in the size of the system and a reorganization of energy flows suggesting a high degree of ecosystem development. All the proxies for ecosystem services show significant decreases in their values. Although representing only a portion of the possible impacts of OA, the findings are consistent with the idea that ecological systems can react to OA effects to maintain the level of ecosystem development, but the new organization might not be optimal from an anthropocentric viewpoint.

Changes in ecosystem properties after post‐fire management strategies in wildfire‐affected Mediterranean forests

Abstract Forest are highly vulnerable to global change drivers, such as an increase in wildfire events. Learning more about how and why different post‐fire management strategies regulate the ability of forest ecosystem properties (e.g. plant diversity and function) to simultaneously recover after wildfire and provide multiple ecosystem functions is of critical importance. This study aims to evaluate how unburned, burned managed and burned unmanaged plots regulate the responses of multiple forest ecosystem properties (e.g. plant diversity, nutrient cycling, soil carbon stocks, water regulation, decomposition and wood production) and overall multifunctionality to wildfires. In September 2017, we selected two post‐fire management strategies in a 3‐km2 watershed previously affected by a wildfire in July 2012: contour‐felled log debris (CFD), log erosion barriers area (LEB), and also unburned and unmanaged plots (BNA). We randomly distributed 12 plots among the three post‐fire management strategies (three plots per treatment) and unburned. The results showed that multiple forest ecosystem properties were significantly affected by wildfire and that specific post‐fire management treatment (e.g. LEB and CFD) can be used to efficiently support plant diversity and ecosystem functioning. Our results revealed that the general indicators of ecosystem functions decreased in Mediterranean forests after wildfires and post‐fire management strategies (LEB and CFD) significantly helped to recover the ecosystems’ short‐term community‐level properties and ecosystem functions (5 years after a wildfire event) to pre‐fire levels. Synthesis and applications. These findings demonstrate that multiple ecosystem functions are affected by wildfires in Mediterranean forests and show that post‐fire management treatments can promote multifunctionality and plant diversity. Our results unfold the potential of log erosion barriers (LEB) and contour‐felled log debris (CFD) as effective strategies for recovering community‐level properties and forest functions in the short term.

Functional Paleoecology and the Pollen-Plant Functional Trait Linkage

Paleoecological investigations using the pollen-plant functional trait linkage are increasing in value as new insights to past ecological function and dynamics are revealed. These retrospective approaches link pollen sequences to plant functional trait measurements to reveal long-term changes in ecosystem properties that are difficult to resolve using traditional paleoecological methods. Despite these methodological improvements and the newfound perspectives, there has yet to be thorough testing of whether transforming pollen to ecological function tracks functional trait distributions in geographic space. We assess this in North America by linking surface pollen samples to measurements of three functional traits that represent major axes of plant ecological strategy. Pollen-derived estimates of function were first used to investigate occupied trait space at different scales. These estimates were used to reconstruct the latitudinal functional diversity gradient of North America, and results were compared to the continent’s functional diversity gradient estimated from tree assemblages and gradients based on pollen richness and evenness. Results indicated that the patterns in pollen-based function sufficiently track ecological function in trait and geographic space and the macroecological biodiversity pattern was reconstructed, although there were minor differences between the slopes of the functional diversity and each of the pollen index gradients. Taken together, the outcomes of our investigation indicate reliability in extending the pollen-plant functional trait linkage into deeper time, at least for examining North American functional dynamics.

Post-fire vegetation succession in the Siberian subarctic tundra over 45 years

Wildfires are relatively rare in subarctic tundra ecosystems, but they can strongly change ecosystem properties. Short-term fire effects on subarctic tundra vegetation are well documented, but long-term vegetation recovery has been studied less. The frequency of tundra fires will increase with climate warming. Understanding the long-term effects of fire is necessary to predict future ecosystem changes.We used a space-for-time approach to assess vegetation recovery after fire over more than four decades. We studied soil and vegetation patterns on three large fire scars (>44, 28 and 12 years old) in dry, lichen-dominated forest tundra in Western Siberia. On 60 plots, we determined soil temperature and permafrost thaw depth, sampled vegetation and measured plant functional traits. We assessed trends in Normalized Difference Vegetation Index (NDVI) to support the field-based results on vegetation recovery.Soil temperature, permafrost thaw depth and total vegetation cover had recovered to pre-fire levels after >44 years, as well as total vegetation cover. In contrast, after >44 years, functional groups had not recovered to the pre-fire state. Burnt areas had lower lichen and higher bryophyte and shrub cover. The dominating shrub species, Betula nana, exhibited a higher vitality (higher specific leaf area and plant height) on burnt compared with control plots, suggesting a fire legacy effect in shrub growth. Our results confirm patterns of shrub encroachment after fire that were detected before in other parts of the Arctic and Subarctic.In the so far poorly studied Western Siberian forest tundra we demonstrate for the first time, long-term fire-legacies on the functional composition of relatively dry shrub- and lichen-dominated vegetation.

Scale-dependency of Arctic ecosystem properties revealed by UAV

In the face of climate change, it is important to estimate changes in key ecosystem properties such as plant biomass and gross primary productivity (GPP). Ground truth estimates and especially experiments are performed at small spatial scales (0.01–1 m2) and scaled up using coarse scale satellite remote sensing products. This will lead to a scaling bias for non-linearly related properties in heterogeneous environments when the relationships are not developed at the same spatial scale as the remote sensing products. We show that unmanned aerial vehicles (UAVs) can reliably measure normalized difference vegetation index (NDVI) at centimeter resolution even in highly heterogeneous Arctic tundra terrain. This reveals that this scaling bias increases most at very fine resolution, but UAVs can overcome this by generating remote sensing products at the same scales as ecological changes occur. Using ground truth data generated at 0.0625 m2 and 1 m2 with Landsat 30 m scale satellite imagery the resulting underestimation is large (8.9%–17.0% for biomass and 5.0%–9.7% for GPP600) and of a magnitude comparable to the expected effects of decades of climate change. Methods to correct this upscaling bias exist but rely on sub-pixel information. Our data shows that this scale-dependency will vary strongly between areas and across seasons, making it hard to derive generalized functions compensating for it. This is particularly relevant to Arctic greening with a predominantly heterogeneous land cover, strong seasonality and much experimental research at sub-meter scale, but also applies to other heterogeneous landscapes. These results demonstrate the value of UAVs for satellite validation. UAVs can bridge between plot scale used in ecological field investigations and coarse scale in satellite monitoring relevant for Earth System Models. Since future climate changes are expected to alter landscape heterogeneity, seasonally updated UAV imagery will be an essential tool to correctly predict landscape-scale changes in ecosystem properties.

Nonlinear dynamics of fires in Africa over recent decades controlled by precipitation.

Dynamics of fires in Africa are of critical importance for understanding changes in ecosystem properties and effects on the global carbon cycle. Given increasing fire risk from projected warming on the one hand and a documented human-driven decline in fires on the other, it is still unknown how the complex interplay between climate and human factors affects recent changes of fires in Africa. Moreover, the impact of recent strong El Niño events on fire dynamics is not yet known. By applying an ensemble empirical mode decomposition method to satellite-derived fire burned area, we investigated the spatio-temporal evolution of fires in Africa over 2001-2016 and identified the potential dominant drivers. Our results show an overall decline of fire rates, which is continuous over the time period and mainly caused by cropland expansion in northern sub-Saharan Africa. However, we also find that years of high precipitation have caused an initial increase in fire rates in southern Africa, which reversed to a decline in later years. This decline is caused by a high frequency of dry years leading to very low fuel loads, suggesting that recent drought causes a general reduction of burned areas, in particular in xeric savannas. In some mesic regions (10°-15°S), solar radiation and increased temperature caused increase in fires. These findings show that climate change overrules the impact of human expansion on fire rates at the continental scale in Africa, reducing the fire risk.

Functional markers to predict forest ecosystem properties along a rural‐to‐urban gradient

AbstractQuestionsWith increasing focus on urban sustainability, new tools are needed to manage urban woodlands for resilience and ecosystem service provision. Functional traits can provide quantitative and testable links between urban plant communities and specific ecosystem properties (functional markers). We ask whether commonly described multivariate patterns of trait association with urbanization (trait syndromes) capture changes in ecosystem properties associated with urbanization. Given that environmental heterogeneity can generate weak or non‐linear trait–ecosystem property relationships, we ask whether linear methods can yield functional markers with significant power for different ecosystem properties.LocationMontreal metropolitan area (Canada).MethodsWe documented the functional composition of 43 woodlands along an urbanization gradient and measured proxies of three ecosystem properties: plant colonization, soil water infiltration and organic matter decomposition. We use redundancy analysis to identify traits associated with urbanization, and multiple linear regression and model selection to identify response and effect traits that best predict actual differences in ecosystem properties. We compare the resulting linear model with a non‐linear equivalent.ResultsTraits associated with urbanization (urban syndrome) were inconsistently selected as best predictors of ecosystems properties (functional markers). Although predictive power varied between ecosystem properties, all three could be significantly predicted from community‐weighted traits (functional markers), with both response and effect traits contributing to the final model. When we fitted equivalent non‐linear models, we found that traits had largely non‐linear relationships with ecosystem properties.ConclusionsOur results demonstrate that community‐weighted traits of urban woodlands can yield functional markers that capture ecosystem properties, but these are inconsistently identified by “trait syndrome” approaches. In linear combinations, such functional markers provide a testable and generalizable way to quantify ecosystem properties in urban woodlands. Capturing such properties is one important step toward management of woodlands for their continued ability to provide ecosystem services into the future.

Three Invasive Tree Species Change Soil Chemistry in Guam Forests

Research Highlights: Established stands of Leucaena leucocephala (Lam.) de Wit, Spathodea campanulata P. Beauv., and Vitex parviflora Juss. modified soils in Guam’s limestone forests, reducing storage pools of carbon, nitrogen, and phosphorus. Background and Objectives: Invasive plants may engineer negative changes in ecosystem properties. This study was conducted to determine changes in soil chemistry following infestations of three problematic tree species on Guam. Materials and Methods: Minerals, metals, and mineralization dynamics were measured in invaded sites and paired sites with biodiverse native tree cover. Results: Most soil properties were significantly changed by long-term infestations of the invasive tree species. The soils within invaded sites exhibited total carbon, total nitrogen, and available phosphorus that were less than native sites. In contrast, the carbon/nitrogen ratio increased for every species-site combination. The other chemical properties were idiosyncratic among the sites and species. Conclusions: Mitigation and restoration activities that include the removal of these trees from project sites may require many years for the below-ground ecosystems to return to their native state. These three invasive trees decrease the ability of Guam soils to sequester recalcitrant forms of carbon, nitrogen, and phosphorus.

Autumn drought drives functional diversity of benthic diatom assemblages of continental intermittent streams

Climate change is predicted to increase drought occurrence and severity in small continental watercourses. Here, we studied the structure and the functional diversity of benthic diatom assemblages in lowland intermittent and permanent watercourses of the Carpathian Basin. We assumed that the community structure of intermittent and permanent watercourses would be markedly different, and the functional diversity in both would be strongly influenced by autumn drought. We found that intermittent streams were primarily characterized by small-sized generalists and aerophilic taxa, while permanent watercourses were inhabited by large-sized planktic or fast moving groups. The functional richness was significantly lower in intermittent than in permanent streams. This decrease in the functional richness of benthic algal communities may negatively affect the functioning of lotic algal communities. We conclude that diatom assemblages in lowland intermittent watercourses are sensitive indicators of changes in ecosystem properties, and should be considered in appropriate evaluation and management of extreme climatic events on aquatic ecosystems.

A 55‐year‐old natural experiment gives evidence of the effects of changes in fire frequency on ecosystem properties in a seasonal subtropical dry forest

AbstractFire frequency has been highlighted as an important component of fire effects on ecosystems; nevertheless, there is scarce information about how fire modulates changes in ecosystem properties, particularly for subtropical dry forests. A long‐term natural experiment and a multiscale approach were used to analyze changes in ecosystem properties in a subtropical dry forest subjected to contrasting fire regimes. Measurements were taken in two adjacent sites that had contrasting fire regimes (low/high fire frequency), and vegetation and soil analyses were combined with dendrochronological methods. Ten plots (20 × 20 m) were established in each site and soil (depth, chemical, and biological properties), and vegetation (species composition and growth of the dominant tree, Lithraea molleoides) variables were measured. Fire scars in L. molleoides were useful in determining fire history. Shrubs and grasses were more abundant in the high fire frequency site, with a high cover of the exotic grass Melinis repens, whereas trees and vines were more abundant in the low fire frequency site. Soil of the high fire frequency site tended to have lower C and nutrient content as well a significant lower depth than those of the low fire frequency site. Growth of L. molleoides individuals was lower in the high fire frequency site. Our results suggest that the long‐term effects of high fire frequency probably increase both soil loss and fire frequency in the future due to changes in plant composition, indicating that frequent burning is not a sustainable management option for this seasonal subtropical dry forest.

A Large Committed Long‐Term Sink of Carbon due to Vegetation Dynamics

AbstractThe terrestrial biosphere shows substantial inertia in its response to environmental change. Hence, assessments of transient changes in ecosystem properties to 2100 do not capture the full magnitude of the response realized once ecosystems reach an effective equilibrium with the changed environmental boundary conditions. This equilibrium state can be termed the committed state, in contrast to a transient state in which the ecosystem is in disequilibrium. The difference in ecosystem properties between the transient and committed states represents the committed change yet to be realized. Here an ensemble of dynamic global vegetation model simulations was used to assess the changes in tree cover and carbon storage for a variety of committed states, relative to a preindustrial baseline, and to attribute the drivers of uncertainty. Using a subset of simulations, the committed changes in these variables post‐2100, assuming climate stabilization, were calculated. The results show large committed changes in tree cover and carbon storage, with model disparities driven by residence time in the tropics, and residence time and productivity in the boreal. Large changes remain ongoing well beyond the end of the 21st century. In boreal ecosystems, the simulated increase in vegetation carbon storage above preindustrial levels was 20–95 Pg C at 2 K of warming, and 45–201 Pg C at 5 K, of which 38–155 Pg C was due to expansion in tree cover. Reducing the large uncertainties in long‐term commitment and rate‐of‐change of terrestrial carbon uptake will be crucial for assessments of emissions budgets consistent with limiting climate change.

Disentangling Effects of Time Since Fire, Overstory Composition and Organic Layer Thickness on Nutrient Availability in Canadian Boreal Forest

Wildfire is the primary abiotic disturbance in the boreal forest, and its long-term absence can lead to large changes in ecosystem properties, including the availability and cycling of nutrients. These effects are, however, often confounded with the effects of successional changes in vegetation toward nutrient-conservative species. We studied a system of boreal forested lake islands in eastern Canada, where time since last fire ranged from 50 to 1500 years, and where the relative abundance of the most nutrient-conservative tree species, black spruce, was largely independent of time since last fire. This allowed us to disentangle the effects of time since fire and the dominant vegetation on ecosystem properties, including nutrient stocks and concentrations. Effects of time since fire independent of vegetation composition mostly involved an increase in the thickness of the organic layer and in nitrogen concentration in both soil and leaves. Domination by black spruce had strong negative effects on nutrient concentrations and was associated with a shift toward more fungi and Gram-positive bacteria in the soil microbial community. Path modeling showed that phosphorus concentration was inversely related to organic layer thickness, which was in turn related to both time since fire and black spruce abundance, while nitrogen was more directly related to time since fire and the composition of the overstory. We conclude that discriminating between the effects of vegetation and time since fire is necessary for better understanding and predicting the long-term changes that occur in forest nutrient availability and ecosystem properties.

Land‐use intensity indirectly affects ecosystem services mainly through plant functional identity in a temperate forest

Abstract Land‐use change is known to affect biodiversity, and there is increasing concern regarding how these changes may impact the provision of ecosystem services. Although functional composition (diversity and identity) could influence ecosystem properties and services at the community level, there is little quantitative understanding of these relationships in the field. Here, we evaluate the direct and indirect effects (through ecosystem properties) of biodiversity on the provision of multiple ecosystem services in native mixed forest in north‐west Patagonia, and how land‐use intensity influences these relationships. We used structural equation modelling to test hypotheses regarding the relationship between understorey plant functional composition, two ecosystem properties, four ecosystem services and silvopastoral use intensity (SUI). We also evaluated two alternative models to assess the mechanism behind biodiversity and ecosystem properties relationships (biomass ratio and niche complementarity). Finally, we performed pairwise correlations to identify synergies and trade‐offs between ecosystem services. SUI affected functional composition, and the provision of three out of four ecosystem services was indirectly affected by land‐use intensity through changes in ecosystem properties. We found that this indirect effect of biodiversity on ecosystem services happens mainly through changes in functional identity rather than functional diversity. Under increasing land‐use intensity, functional composition changed towards a community characterized by a resource acquisition strategy. Trade‐offs between ecosystem services (provisioning vs. regulating) were enhanced under high SUI, while synergies where enhanced under low SUI (provisioning vs. cultural). Thus, although the strength of these relationships varied between SUI, its nature (trade‐off or synergy) stayed the same. Our results expand on previous studies by simultaneously considering the effect of land‐use intensification directly on functional composition and on the ecosystem processes underpinning ecosystem services, as well as on the relationship among them. We provide evidence of an indirect effect of land‐use intensification on multiple ecosystem services through biodiversity. Moreover, we found that functional identity is more important than diversity for ecosystem functionality. Land‐use intensification affects biodiversity, and thus, ecosystem properties, but does not change the relationship among ecosystem services. A plain language summary is available for this article.

Functional and structural responses to marine urbanisation

Urban areas have broad ecological footprints with complex impacts on natural systems. In coastal areas, growing populations are advancing their urban footprint into the ocean through the construction of seawalls and other built infrastructure. While we have some understanding of how urbanisation might drive functional change in terrestrial ecosystems, coastal systems have been largely overlooked. This study is one of the first to directly assess how changes in diversity relate to changes in ecosystem properties and functions (e.g. productivity, filtration rates) of artificial and natural habitats in one of the largest urbanised estuaries in the world, Sydney Harbour. We complemented our surveys with an extensive literature search. We found large and important differences in the community structure and function between artificial and natural coastal habitats. However, differences in diversity and abundance of organisms do not necessarily match observed functional changes. The abundance and composition of important functional groups differed among habitats with rocky shores having 40% and 70% more grazers than seawalls or pilings, respectively. In contrast, scavengers were approximately 8 times more abundant on seawalls than on pilings or rocky shores and algae were more diverse on natural rocky shores and seawalls than on pilings. Our results confirm previous findings in the literature. Oysters were more abundant on pilings than on rocky shores, but were also smaller. Interestingly, these differences in oyster populations did not affect in situ filtration rates between habitats. Seawalls were the most invaded habitats while pilings supported greater secondary productivity than other habitats. This study highlights the complexity of the diversity-function relationship and responses to ocean sprawl in coastal systems. Importantly, we showed that functional properties should be considered independently from structural change if we are to design and manage artificial habitats in ways to maximise the services provided by urban coastal systems and minimise their ecological impacts.

Individual-level trait diversity predicts phytoplankton community properties better than species richness or evenness.

Understanding how microbial diversity influences ecosystem properties is of paramount importance. Cellular traits-which determine responses to the abiotic and biotic environment-may help us rigorously link them. However, our capacity to measure traits in natural communities has thus far been limited. Here we compared the predictive power of trait richness (trait space coverage), evenness (regularity in trait distribution) and divergence (prevalence of extreme phenotypes) derived from individual-based measurements with two species-level metrics (taxonomic richness and evenness) when modelling the productivity of natural phytoplankton communities. Using phytoplankton data obtained from 28 lakes sampled at different spatial and temporal scales, we found that the diversity in individual-level morphophysiological traits strongly improved our ability to predict community resource-use and biomass yield. Trait evenness-the regularity in distribution of individual cells/colonies within the trait space-was the strongest predictor, exhibiting a robust negative relationship across scales. Our study suggests that quantifying individual microbial phenotypes in trait space may help us understand how to link physiology to ecosystem-scale processes. Elucidating the mechanisms scaling individual-level trait variation to microbial community dynamics could there improve our ability to forecast changes in ecosystem properties across environmental gradients.