The expansion of Moso bamboo (Phyllostachys edulis) significantly alters the spatial configuration of surrounding trees, leading to dynamic shifts in the spatial distribution of coarse woody debris (CWD). Investigating the spatial patterns of CWD during bamboo expansion can reveal the dynamic mechanisms of forest communities in this process, thereby providing scientific insights for forest management and conservation. In this study, conducted within the Yangjifeng Biodiversity Monitoring Large Plot, all trees with a diameter at breast height (DBH) >= 1 cm within the plots were tagged and important variables were measured, including DBH, tree height, and spatial attributes. Coarse woody debris (CWD) with a DBH >= 10 cm was also measured, including DBH, diameters at both ends, length, and spatial attributes. Based on the importance values of tree species in each 20 m & times; 20 m plot-where an importance value comprehensively measured a species' relative abundance, frequency, and dominance in the community-the sample plots were divided into three continuous sample transects: evergreen broad-leaved forest (EBF), bamboo-broadleaf mixed forest (BMF), and Phyllostachys edulis forest (PEF). Ripley's 'g'-function was employed to analyze the spatial patterns and associations of CWD across these three forest types. A random sampling approach was used to collect CWD samples for the measurement and calculation of carbon storage. Three key findings emerged. (1) With the expansion of Moso bamboo, the biomass and carbon storage of standing dead trees both decrease. The biomass is highest in EBF, followed by BMF and PEF. However, carbon storage is greatest in BMF and lowest in PEF. (2) With the expansion of Moso bamboo, the distribution of CWD became increasingly uniform in PEF; analysis of the overall spatial pattern of CWD indicated that with increasing spatial scale, CWD changed from an aggregated to a random distribution across all three forest types, with a pattern scale of approximately 10 m. In EBF, the CWD of Moso bamboo exhibited a random distribution at all spatial scales. Additionally, CWD across different diameter classes, decay stages, and types changed from aggregated to random distributions as the spatial scale increased, with a reduction in aggregation intensity correlated with larger diameter classes. (3) Finally, we found an almost exclusively negative spatial association between living trees and CWD across all scales, and this negative correlation may be attributed to the absence of new tree growth following tree mortality. Collectively, our findings demonstrate that during Moso bamboo expansion, the spatial distribution of CWD changes from aggregated to random, while maintaining a significantly negative spatial association with living trees. This reveals the dynamic changes in the spatial patterns of CWD during community development, thereby providing a scientific basis for the forest management of subtropical evergreen broadleaf forests and bamboo management and control.

Lianas are woody vines that rely on host trees for support to access the forest canopy. Lianas typically occur in tropical and subtropical forests and coexist with trees in subtropical secondary forests, where their interactions strongly influence forests communities and ecosystem functioning. We compared stem and leaf traits of lianas and trees to examine the effects of growth form and leaf habit. We measured 20 functional traits (9 stem anatomical/hydraulic and 11 leaf morphological/nutrient) from 10 liana and 14 tree species coexisting in a subtropical forest of south China. Lianas exhibited 3.5‐fold higher sapwood specific conductivity ( K s ) than trees, as well as higher predawn leaf water potential (Ψ predawn ) and hydraulically weighted vessel diameter ( D h ). Additionally, maximum vessel diameter ( D max ) of lianas approximately three times higher than that of trees, and theoretical hydraulic conductivity ( K p ) was ~20 times higher than trees. Functional trait analysis indicated that lianas grouped separately from trees along a leaf and stem economics spectrum: lianas were grouped together at the fast end of the plant economics spectrum, with high hydraulic diameter ( D h ) and high nitrogen (N) and phosphorus (P) concentration, exhibiting an acquisition‐focused water and nutrient strategy, permitting rapid growth and tissue turnover. Trees were grouped at the low end of the plant economics spectrum, with a high C:N ratio, high vessel thickness/diameter (VT/VD) and high wood density (WD), exhibiting a conservative resource acquisition strategy. Moreover, lianas exhibited significantly higher modularity in their trait networks compared to trees (0.490 vs 0.345; p = 0.043), reflecting stronger local integration of function, with tightly coordinated traits that may enhance system adaptability by limiting the spread of local drought‐induced stress. These findings improve our understanding of the mechanisms shaping ecological strategies across woody plants with different growth forms and leaf habits, and addresses the limited trait‐based knowledge of subtropical forests relative to tropics. This study provides novel insight into how growth form and leaf habit shape resource acquisition and niche partitioning in co‐occurring woody species in a subtropical and secondary forests. Read the free Plain Language Summary for this article on the Journal blog.

Studies of stream macroinvertebrates traditionally use sampling methods that target benthic habitats. These methods could underestimate biodiversity if important assemblage components exist outside of the benthic zone. To test the efficacy of different sampling methods, we collected paired reach-wide benthic and edge samples from up to 10 study reaches in nine basins spanning an aridity gradient across the United States. Edge sampling targeted riparian-adjacent microhabitats not typically sampled, including submerged vegetation, roots, and overhanging banks. We compared observed richness, asymptotic richness, and assemblage dissimilarity between benthic samples alone and different combinations of benthic and edge samples to determine the magnitude of increased diversity and assemblage dissimilarity values with the addition of edge sampling. We also examined how differences in richness and assemblage composition varied across an aridity gradient. The addition of edge sampling significantly increased observed richness (median increase = 29%) and asymptotic richness (median increase = 173%). Similarly, median Bray-Curtis dissimilarity values increased by as much as 0.178 when benthic and edge samples were combined. Differences in richness metrics were generally higher in arid basins, but assemblage dissimilarity either increased or decreased across the aridity gradient depending on how benthic and edge samples were combined. Our results suggest that studies that do not sample stream edges may significantly underestimate reach diversity and misrepresent assemblage compositions, with effects that can vary across climates. We urge researchers to carefully consider sampling methods in field studies spanning climatic zones and the comparability of existing data sets when conducting data synthesis studies.

(1) Background: Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) expansion has seriously altered the species composition and structure of adjacent forest ecosystems in subtropical regions. However, the shift in phosphorus (P) biogeochemical cycling has yet to be assessed, which is a critical gap considering the great variation in ecophysiological properties between invasive bamboo and the displaced native tree species. (2) Methods: We investigated and compared expansion-induced changes in P pools (plant, litter, and soil) and P fluxes (plant uptake and litterfall return) using paired sampling of the bamboo-dominated forest (BDF) and secondary evergreen broadleaved forest (EBF) at Jiangxi province’s Dagang Mountain National Forest Ecological Station. (3) Results: Both the P storage of the plants and litter were significantly greater by 31.8% and 68.2% in the BDF than in the EBF, respectively. The soil total P and available P storage were 28.9% and 40.4% lower, respectively, in the BDF than in the EBF. Plant P uptake was 15.6% higher in the BDF than in the EBF, and the annual litter P return was 26.1% lower in the BDF than in the EBF due to higher P resorption efficiency for moso bamboo compared with evergreen broadleaved tree species. The ecosystem P cycling rate was reduced by 36.1% in the BDF compared with the EBF. (4) Conclusions: Moso bamboo expansion slowed the broadleaved forest ecosystem’s P cycle rate, likely because moso bamboo has higher P-use efficiency, reserving more P in its tissues rather than returning it to the soil. The results from this study elucidate an understudied element cycle in the context of forest succession, demonstrating the ecosystem consequences related to bamboo invasion.

Conventional management (CM), substantial fertilization and flooding irrigation, has led to soil acidification, the decrease in soil bacterial diversity in bamboo forests. Integration of water and fertilizer management (IWF) can effectively improve the efficiency of water and fertilizer use, but its effect on soil environment, especially on microbial community, is still unclear. Here, we used next-generation high-throughput sequencing to compare soil properties and bacterial communities through different fertilization and irrigation methods under IWF and CM. Compared to the control group, CM significantly reduced soil pH and bacterial diversity, while IWF improved soil nutrition status, increased soil bacterial diversity and soil pH to a level similar to the control group. Compared with CM, IWF also improved the relative abundance of beneficial bacteria and copiotrophic bacteria community in the soil, and the bacterial community in IWF was similar to CK. The structure of the bacterial community was also significantly correlated with soil organic matter, total nitrogen, hydrolyzable nitrogen, and available potassium, while soil bacterial diversity was mainly associated with soil hydrolyzable nitrogen. IWF can play an important role in preventing soil acidification, the loss of soil bacterial diversity, and improving the structure of the bacterial community under specific conditions.

Background and aims Subtle morphological traits, such as leaf litter curling, may have unexpected legacy effects on ecosystems. We tested the hypotheses that litter curling is influenced by plant species, hybridization and genotype, and has extended consequences for associated organisms and soil processes. Methods A novel litter curling index (LCI) was used to characterize the curling of leaf litter from 11 plant species (including shrubs, trees and a forb) in natural field sites and of two Populus species ( P. fremontii James, P. angustifolia S. Watson), their F 1 hybrids and replicated P. angustifolia genotypes from a common garden. Surveys of dominant, litter-dwelling spiders (Agelenidae), and a soil drying experiment, were used to test the potential extended ecological consequences of litter curling. Results Five results emerged. (1) LCI ranged 15-fold among plant species in natural sites. (2) LCI nearly doubled from P. fremontii to P. angustifolia , while average LCI for F 1 hybrids was intermediate (although not statistically different from P. fremontii ). (3) LCI exhibited broad-sense heritability ( H 2 = 0.42) among P. angustifolia genotypes. (4) Abundance of spider webs was positively associated with increasing litter curl across the Populus hybrid system ( R 2 = 0.35). (5) After 57 days of drying, flat litter contained 1.4 times higher moisture than curled litter, which translated to wetter soil beneath flat litter. Conclusion Litter curling has a genetic basis, which has legacy effects on other trophic levels and soil moisture dynamics that may shape the ecology and evolution of complex communities.

Aims Moso bamboo ( Phyllostachys pubescens ) invasions into native forest cause a series of ecological problems, including the alteration of soil microorganism community composition. Additionally, it has been established that variation changes in leaf litter types can drive changes in soil microorganism communities. We have previously demonstrated distinct differences in nutrient composition between bamboo leaf litter and leaf litter of native plants. Yet to date, we lack a comprehensive understanding of how Moso bamboo leaf litter inputs change soil microorganism community composition in native forests. Methods We conducted an in-situ decomposition experiment to examine the response of soil bacterial and fungi phyla to Moso bamboo leaf litter addition in three native forest soils. Results Bamboo leaf litter had higher quality (low lignin content and low C:N) and higher decomposition rates compared to native forest plants. Bamboo leaf litter additions did not change the richness and diversity of soil bacterial and fungi in the Broadleaf forest and Chinese fir forest. Additionally, bamboo leaf litter additions only affected the soil microorganisms in the Cryptomeria japonica var. Sinensis forest with low-quality litter; Principal Component Analysis (PCA) further supported this result. Conclusions Our results demonstrate that the soil microbial community has resilience to chemical and biotic inputs from foreign leaf litter. This study helps soil ecologists better understand the impacts of Moso bamboo invasions into native forests, including the weak effects of its litter input on soil microorganisms.

Abstract Background Silicon (Si), while not an essential element for plant growth, can be important for high Si-accumulating Poaceae, such as Moso bamboo. However, other trees do not actively take up dissolved silicic acid [Si(OH)4] from the soil, likely because they have fewer or no specific Si transporters in their roots. It is unclear what causes the different growth and nutrient status between bamboo and other trees under varying Si supply. Results In this study, we found that Si addition increased the biomass production of P. pubescens saplings, likely by improving its net photosynthetic rate and nutrient status, which contrasted to the saplings of P. bournei and S. superba. In addition, we found that C concentrations of aboveground tissues in P. pubescens declined with increasing Si supply, likely due to a partial substitution of organic C compounds by Si. Si addition increased the foliar C:N stoichiometry in the saplings of P. bournei and S. superba through altering their concentration of C and N, but did not affect the C:N or N:P stoichiometry of C. lanceolata and P. pubescens. Conclusions Si elicited either a positive or negative effect on plants, such as improve or weaken photosynthetic capacity, increase or decrease the concentration of C and N in plants, depending much on plant species and the Si supply level of in the environment. These results have implications for assessing the growth and nutrient status between bamboo and trees (i.e, high Si-accumulating plants compared to other plants) when Si availability is altered in ecosystems.

DNA-based aquatic biomonitoring methods show promise to provide rapid, standardized, and efficient biodiversity assessment to supplement and in some cases replace current morphology-based approaches that are often less efficient and can produce inconsistent results. Despite this potential, broad-scale adoption of DNA-based approaches by end-users remains limited, and studies on how these two approaches differ in detecting aquatic biodiversity across large spatial scales are lacking. Here, we present a comparison of DNA metabarcoding and morphological identification, leveraging national-scale, open-source, ecological datasets from the National Ecological Observatory Network (NEON). Across 24 wadeable streams in North America with 179 paired sample comparisons, we found that DNA metabarcoding detected twice as many unique taxa than morphological identification overall. The two approaches showed poor congruence in detecting the same taxa, averaging 59%, 35%, and 23% of shared taxa detected at the order, family, and genus levels, respectively. Importantly, the two approaches detected different proportions of indicator taxa like %EPT and %Chironomidae. DNA metabarcoding detected far fewer Chironomid and Trichopteran taxa than morphological identification, but more Ephemeropteran and Plecopteran taxa, a result likely due to primer choice. Overall, our results showed that DNA metabarcoding and morphological identification detected different benthic macroinvertebrate communities. Despite these differences, we found that the same environmental variables were correlated with invertebrate community structure, suggesting that both approaches can accurately detect biodiversity patterns across environmental gradients. Further refinement of DNA metabarcoding protocols, primers, and reference libraries-as well as more standardized, large-scale comparative studies-may improve our understanding of the taxonomic agreement and data linkages between DNA metabarcoding and morphological approaches.

IntroductionConsiderable evidence indicates that some trees are more vulnerable than others during bamboo (Phyllostachys edulis) expansion, which can affect plant community structure and alter the environment, but there has been insufficient research on the growth status of surviving individuals in colonized forests.MethodsIn this study, we compared the annual growth increment, growth rate, and onset, cessation, and duration of radial growth of Alniphyllum fortunei, Machilus pauhoi, and Castanopsis eyrei in a bamboo-expended broadleaf forest (BEBF) and a bamboo-absent broadleaf forest (BABF) using high-resolution point dendrometers.ResultsWe found that the annual radial growth of A. fortunei, M. pauhoi, and C. eyrei was 22.5%, 172.2%, and 59.3% greater in BEBF than in BABF, respectively. The growth rates of M. pauhoi and C. eyrei in BEBF were significantly higher than in BABF by13.9 μm/d and 19.6 μm/d, whereas A. fortunei decreased significantly by 7.9 μm/d from BABF to BEBF. The onset and cessation of broad-leaf tree growth was later, and the growth duration was longer in BEBF compared to BABF. For example, A. fortunei and M. pauhoi in BEBF had more than one month longer growth duration than in BABF. Additionally, the nighttime growth rates of some surviving broad-leaf trees in BEBF was significantly higher than that in BABF.DiscussionThese results suggest that the surviving trees have plasticity and can adapt to atmospheric changes and competitive relationships after expansion of bamboo in one of two ways: by increasing their growth rates or by modifying onset and cessation of growth to extend the growth duration of trees or avoid the period of intense competition with bamboo, thereby growing better. Our research reveals for the first time how the growth of surviving broad-leaf trees adjusts to bamboo expansion. These results provide insights into how biological expansions impact primary production and have implications for forest management in the Anthropocene.

BACKGROUND:Si can be important for the growth, functioning, and stoichiometric regulation of nutrients for high-Si-accumulating bamboo. However, other trees do not actively take up dissolved silicic acid [Si(OH)4] from the soil, likely because they have fewer or no specific Si transporters in their roots. It is unclear what causes differential growth and C:N:P stoichiometry between bamboo and other trees across levels of Si supply.RESULTS:Si supply increased the relative growth rate of height and basal diameter of bamboo saplings, likely by increasing its net photosynthetic rate and ratios of N:P. Moreover, a high concentration of Si supply decreased the ratio of C:Si in bamboo leaves due to a partial substitution of C with Si in organic compounds. We also found that there was a positive correlation between leaf Si concentration and its transpiration rate in tree saplings.CONCLUSIONS:We demonstrated that Si supply can decrease the ratio of C:Si in bamboo leaves and increase the ratio of N:P without altering nutrient status or the N:P ratio of tree saplings. Our findings provide experimental data to assess the different responses between bamboo and other trees in terms of growth, photosynthesis, and C:N:P stoichiometry. These results have implications for assessing the growth and competition between high-Si-accumulating bamboo and other plants when Si availability is altered in ecosystems during bamboo expansion.

The delivery of consistent and accurate fine‐resolution data on biodiversity using metabarcoding promises to improve environmental assessment and research. Whilst this approach is a substantial improvement upon traditional techniques, critics note that metabarcoding data are suitable for establishing taxon occurrence, but not abundance. We propose a novel hierarchical approach to recovering abundance information from metabarcoding, and demonstrate this technique using benthic macroinvertebrates. To sample a range of abundance structures without introducing additional changes in composition, we combined seasonal surveys with fish‐exclusion experiments at Catamaran Brook in northern New Brunswick, Canada. Five monthly surveys collected 31 benthic samples for DNA metabarcoding divided between caged and control treatments. A further six samples per survey were processed using traditional morphological identification for comparison. By estimating the probability of detecting a single individual, multispecies abundance models infer changes in abundance based on changes in detection frequency. Using replicate detections of 184 genera (and 318 species) from metabarcoding samples, our analysis identified changes in abundance arising from both seasonal dynamics and the exclusion of fish predators. Counts obtained from morphological samples were highly variable, a feature that limited the opportunity for more robust comparison, and emphasizing the difficulty standard methods also face to detect changes in abundance. Our approach is the first to demonstrate how quantitative estimates of abundance can be made using metabarcoding, both among species within sites as well as within species among sites. Many samples are required to capture true abundance patterns, particularly in streams where counts are highly variable, but few studies can afford to process entire samples. Our approach allows study of responses across whole communities, and at fine taxonomic resolution. We discuss how ecological studies can use additional sampling to capture changes in abundance at fine resolution, and how this can complement broad‐scale biomonitoring using DNA metabarcoding.

The aim of this study was to understand the encroachment order, spatial patterns, interspecific associations, and species diversity of a Cunninghamia lanceolata plantation and to provide context for how to improve the spatial structure of C. lanceolata plantations. We investigated a Guanshan (C. lanceolata) Plantation in the Jiangxi Province. The C. lanceolata plantation was divided into three developmental stages (early, middle and late), with a space-for-time substitution method, according to their diameter at breast height (DBH) measurements. Across these plots, we analyzed encroachment patterns of the species and their interspecific associations with C. lanceolata according to the coordinates of trees in the plot, as well as the variation of species diversity after the encroachment of broad-leaf tree species. Our results show that the encroachment of broad-leaf trees into the C. lanceolata plantation followed a clear successional sequence of tree community assembly: intolerant tree species encroachment first, such as Alniphyllum fortunei and Liquidambar formosana, encroached; neutral tree species then encroachment, such as Daphniphyllum oldhamii and Schima superba, and shade-tolerant tree species encroachment last, such as Castanopsis eyrei and Castanopsis tibetana. Further, the spatial pattern of species establishment differed based upon when they encroached on the plantation. Intolerant and neutral tree species of early and middle developmental stages were distributed randomly. However, intolerant and some shade-tolerant tree species of the late developmental stage were aggregated on a scale of about 0–3 m. In addition, the interspecific associations between broad-leaf species encroachment into the C. lanceolata plantation were mainly negative, among which the most competitive ones were A. fortunei, D. oldhamii and Machilus thunbergii. However, with the development of the community, some species with negative correlations changed to having no correlation with C. lanceolata. We found that species diversity in the plantation gradually increased by nearly-five times from the early to the late developmental stage. Based on our collective results, we conclude that the encroachment and assembly of tree species show obvious order and pattern, which has a strong competitive effect with C. lanceolata in the naturalized plantation. Additionally, the community biodiversity has been significantly improved. Therefore, this successional process is important in the transformation of the C lanceolata plantation and different tree species should be replanted according to C. lanceolata plantation developmental stages with priority given to competitive species, such as A. fortunei, D. oldhamii, and M. thunbergii, so as to promote the C. lanceolata plantation change to C. lanceolata and broadleaf mixed forest.

The biodiversity-ecosystem function hypothesis postulates that higher biodiversity is correlated with faster ecosystem process rates and increased ecosystem stability in fluctuating environments. Exhibiting high spatiotemporal habitat diversity, floodplains are highly productive ecosystems, supporting communities that are naturally resilient and highly diverse. We examined linkages among floodplain wetland habitats, invertebrate communities and their associated traits, and ecosystem function across 60 sites within the floodplain wetlands of the lower Wolastoq | Saint John River, New Brunswick, using structural equation modelling and Threshold Indicator Taxa ANalysis. We identified key environmental filters structuring invertebrate communities, by linking increased niche differentiation through shoreline change, flood pulse dynamics, and macrophyte bed complexity with increased taxa and functional diversity. Examination of traits linked to ecosystem functions revealed that more resilient wetlands with balance between primary productivity and decomposition as carbon sources were associated with greater functional evenness and richness, while habitat patches with elevated decomposition rates had lower functional richness, reflecting a simplified, more disturbed habitat. While our more complex overarching SEM model was ultimately compromised by an overspecified number of pathways, our results nevertheless are indicative of a divergence between wetland and riverine ecosystems in their relationships linking biodiversity and ecosystem function, illustrating how to define ecosystem health in wetland habitats, and demonstrating how critical functions support healthy wetland habitats by providing increased resilience to disturbance. Read the free Plain Language Summary for this article on the Journal blog.

River bioassessment programs require robust methods to accurately observe the status of aquatic biodiversity, as it is well understood that physico-chemical monitoring alone is not sufficient to support current policy and management objectives. Whereas traditional microscopy-based identification of organisms can be expensive and laborious, direct sampling of environmental DNA, coupled with high-throughput sequencing technologies, now provides a rapid and accurate alternative to support bioassessment analysis and interpretation. Here, we discuss the various insights that can be generated from eDNA, illustrate how river monitoring can benefit from eDNA approaches, knowledge gaps, and how this can support bioassessment from local to national and international scales.

Abstract AimsSilicon (Si), while not an essential element for plant growth, can be important for high Si-accumulating Poaceae, such as Moso bamboo. However, other trees do not actively take up dissolved silicic acid [Si(OH)4] from the soil, likely because they have fewer or no specific Si transporters in their roots. It is unclear what causes the different growth and nutrient status between bamboo and other trees under varying Si supply. To explore the influences of Si availability on the growth, photosynthesis, nutrient status and C:N:P stoichiometry of bamboo and other trees.MethodsWe used one-year seedlings of P. pubescens, P. bournei, S. superba and C. lanceolata in a pot experiment where three widely differing levels of silicon were supplied, and measured growth traits, photosynthetic gas exchange properties and C:N:P stoichiometry of seedling responses to three levels Si supply and analyzed the impacts of Si supply on growth and nutrient status of bamboo and tree saplings.ResultsWe found that Si increased the biomass production of P. pubescens seedlings with the higher concentration of Si supply, likely by improving its photosynthesis and nutrient status net photosynthetic rate, which contrasted to the seedlings of P. bournei and S. superba. In addition, we found that C concentrations of aboveground tissues in P. pubescens declined with increasing Si supply, likely due to a partial substitution of organic C compounds by Si. We also found that Si treatments increased the foliar C:N stoichiometry in the seedlings of P. bournei and S. superba through altering their concentration of C and N, but did not affect the C:N or N:P stoichiometry of C. lanceolata and P. pubescens.ConclusionsSi elicited either a positive or negative effect on plants, such as improve or weaken photosynthetic capacity, increase or decrease the concentration of C and N in plants, depending much on plant species and the ambient supply level of Si in the environment. These results have implications for assessing the growth and nutrient status between bamboo and other trees (i.e, high Si-accumulating plants compared to other plants) when Si availability is altered in ecosystems, such as when Si availability in ecosystems is altered by bamboo expansion.

Floodplains are disturbance-driven ecosystems with high spatial and temporal habitat diversity, making them both highly productive and hosts to high biodiversity. The unpredictable timing of flood and drought years creates a mosaic of habitat patches at different stages of succession, while water level fluctuation directly influences macrophyte community dynamics, and thus habitat structure. This habitat complexity and diversity of disturbance regimes makes floodplains an ideal ecosystem in which to examine the links between biodiversity, traits and ecosystem function. With up to 90% of floodplains in North America and Europe altered to the point of functional extinction, it is particularly imperative to study and conserve those that remain intact, such as the Lower Saint John River and its associated floodplain, including the Grand Lake Meadows and Portobello Creek wetland complex. Despite the rise in trait-based science, taxonomic resolution has imposed limitations, especially in wetland and floodplain ecosystems where communities are vastly understudied compared to their riverine counterparts. Compared to traditional biomonitoring, DNA-based biomonitoring from high-throughput genomics sequencing methods is powerful in that it can reliably characterize community composition in unprecedented detail, allowing us to assess how disturbance and environmental filters interact with invertebrate traits and ecosystem function. Using structural equation analysis, we take a whole ecosystem approach to examine ecosystem health across a floodplain disturbance gradient. We focus chiefly on how anthropogenic alteration within watersheds affects downstream floodplain wetlands, how the resulting patch diversity shapes communities and, finally, how those communities influence ecosystem function through trait diversity metrics. We also examine and compare which traits are associated with crucial ecosystem gradients.

Efforts to maintain the function of critical ecosystems under climate change often begin with foundation species. In the southwestern United States, cottonwood trees support diverse communities in riparian ecosystems that are threatened by rising temperatures. Genetic variation within cottonwoods shapes communities and ecosystems, but these effects may be modified by phenotypic plasticity, where genotype traits change in response to environmental conditions. Here, we investigated plasticity in Fremont cottonwood (Populus fremontii) leaf litter traits as well as the consequences of plasticity for riparian ecosystems. We used three common gardens each planted with genotypes from six genetically divergent populations spanning a 12°C temperature gradient, and a decomposition experiment in a common stream environment. We found that leaf litter area, specific leaf area, and carbon to nitrogen ratio (C:N) were determined by interactions between genetics and growing environment, as was the subsequent rate of litter decomposition. Most of the genetic variation in leaf litter traits appeared among rather than within source populations with distinct climate histories. Source populations from hotter climates generally produced litter that decomposed more quickly, but plasticity varied the magnitude of this effect. We also found that hotter growing conditions reduced the variation in litter traits produced across genotypes, homogenizing the litter inputs to riparian ecosystems. All genotypes in the hottest garden produced comparatively small leaves that decomposed quickly and supported lower abundances of aquatic invertebrates, whereas the same genotypes in the coldest garden produced litter with distinct morphologies and decomposition rates. Our results suggest that plastic responses to climate stress may constrict the expression of genetic variation in predictable ways that impact communities and ecosystems. Understanding these interactions between genetic and environmental variation is critical to our ability to plan for the role of foundation species when managing and restoring riparian ecosystems in a warming world.

Abstract The introduction of non-native predators is a matter of great concern, but their impacts on ecosystem functions remain poorly understood. We investigated how changes in fish diversity following the invasion of Cichla kelberi affected ecosystem functions generated by fish populations. Fish assemblages were sampled in macrophyte patches in a Neotropical impoundment over a 5-year period, before and after the introduction of the predator. We assigned seven ecosystem functions (26 trait-states) to each fish species, and examined how these functions behaved after the invasion. We collected 577 fish belonging to 25 species. Species richness, fish biomass and main species declined significantly over periods. The biomass of ecosystem functions changed significantly over time, and most trait-states declined. Few trait-states were lost, but all functions had at least one trait-state reduced by more than 85%. A null model analysis showed that changes in functions were not driven by species identities, while species richness correlated positively with total biomass and with most functions, suggesting that the loss of taxa and biomass drove observed changes in ecosystem functions. Our study provided evidence that community disassembly associated with the invasion of C. kelberi translated to the decline of several ecosystem functions, affecting energy mobilization and transference.