Osteoarthritis Disease Severity in the Temporomandibular Joint and the Knee Joint: A Comparative Cadaveric Study.

OBJECTIVE: The objective of this study was to determine the level of disease severity in a pilot cohort of temporomandibular joints (TMJs) and compare them to the pathology findings previously characterized in cadaveric knee joints. DESIGN: Thirty-one intact TMJs from 17 cadaveric donors were harvested and arthritic lesioning seen in the knee joint was investigated on the condyle and the fossa of the TMJ. Prevalence of gross alterations was equated and disease severity was determined for sex- and age-based donor pools using a validated, osteoarthritis (OA) disease severity scale (DSS). Knee joint DSS scores were also compared to the TMJ condyle and fossa DSS scores and a case study was carried out on a male donor that demonstrated severe OA in the both joints. RESULTS: The mandibular fossa demonstrated an increase in disease severity compared to the mandibular condyle in a mixed sex donor pool (P = 0.035). It was discovered that the younger females demonstrated statistically more pathological condyles compared to the older half of the female subgroup (P = 0.02). TMJ fossa and knee joints demonstrated comparable OA severity and similar signs of cartilage disease in a single donor highlighting the systemic nature of OA. CONCLUSIONS: This study demonstrates that gross signs of OA in the TMJs of cadavers are comparable to pathology found in the knee. The mandibular fossa appears to be the site of more profound disease, implying translational movements may be more likely to induce biomechanically abnormal movement, loading, and OA.

Drivers of seedling establishment success in dryland restoration efforts.

Restoration of degraded drylands is urgently needed to mitigate climate change, reverse desertification and secure livelihoods for the two billion people who live in these areas. Bold global targets have been set for dryland restoration to restore millions of hectares of degraded land. These targets have been questioned as overly ambitious, but without a global evaluation of successes and failures it is impossible to gauge feasibility. Here we examine restoration seeding outcomes across 174 sites on six continents, encompassing 594,065 observations of 671 plant species. Our findings suggest reasons for optimism. Seeding had a positive impact on species presence: in almost a third of all treatments, 100% of species seeded were growing at first monitoring. However, dryland restoration is risky: 17% of projects failed, with no establishment of any seeded species, and consistent declines were found in seeded species as projects matured. Across projects, higher seeding rates and larger seed sizes resulted in a greater probability of recruitment, with further influences on species success including site aridity, taxonomic identity and species life form. Our findings suggest that investigations examining these predictive factors will yield more effective and informed restoration decision-making.

Do shrubs improve reproductive chances of neighbors across soil types in drought?

Plant reproduction is highly sensitive to stress from severe weather. While facilitation has been shown to buffer negative impacts along stress gradients, less is known about facilitating plant reproduction in drought periods. Because intensity and frequency of drought are predicted to increase, plant reproductive facilitation has important implications for a species ability to adapt to changes in climate. Our primary study objective is to test if nurse shrubs act as reproductive micro-refugia across soil types, by improving reproductive potential of perennial bunchgrass neighbors subjected to severe drought. To investigate this objective, we designed a fully factored study testing direct interaction between shrub and bunchgrasses in eastern Oregon sagebrush steppe, at two sites with different soil types. The study consisted of six simple effect treatments combining three moisture regimes (moist, ambient, and drought) with two shrub conditions (shrub intact or shrub removed). Our results indicate when facilitation of reproductive potential occurs, it occurs strongly and particularly in drought, consistent with the stress gradient hypothesis (SGH), where several species produced at least 54% more inflorescences in the presence of shrub neighbors. In addition, we found facilitation to be consistent with the SGH at the species level likely reflecting differences in plant strategy and perception of strain, but to follow alternative SGH models more closely at the site level where facilitation declined on the drier soil. Ultimately, our findings highlight the importance of facilitation in improving plant reproductive potential in drought, and support the role of nurse shrubs as micro-refugia in a changing climate.

Takotsubo Cardiomyopathy Induced by Epinephrine Infiltration for Liposuction: Broken Heart Syndrome.

Broken heart syndrome, more commonly known as Takotsubo cardiomyopathy (TCM), is an acute cardiac condition. It is characterized by regional cardiac wall motion abnormalities triggered by physical or emotional stress or administration of catecholamines such as epinephrine. The initial clinical presentation is similar to an acute coronary syndrome and must be ruled out. Visualization of the characteristic wall motion will trigger the diagnosis of TCM. In this case report, we present a 50-year-old woman with additional liposuction and fat grafting after autologous breast reconstruction. Shortly after infiltration with a solution containing epinephrine to achieve vasoconstriction, hypotension and bradycardia was noticed. This escalated into full asystole for which cardiac resuscitation was required. ST-elevations and a decrease in systolic function were clear indicators for urgent coronarography and ventriculography. These confirmed the diagnosis of TCM. Infiltration with epinephrine-containing products to achieve local vasoconstriction is used routinely. Medical professionals should be aware that this can trigger a TCM with an estimated mortality rate of 5%. No evidence of a specific preventive measure currently exists. We know that women with a neurologic or psychiatric comorbidity and high levels of stress are more at risk. Reducing stress and anxiolytic medication prior to surgery could be useful. We also know that the cardiac wall motion abnormality is mainly related to ß-adrenoreceptors. The use of a selective α-adrenoreceptor agonist could be considered. Further research in the pathophysiology and incidence of TCM could improve identification of patients at risk and lead to more effective prevention and treatment.

Functional Traits Explain Variation in Chaparral Shrub Sensitivity to Altered Water and Nutrient Availability.

Worldwide drylands are threatened by changes in resource availability associated with global environmental change. Functional traits may help predict which species will be most responsive to these alterations in nutrient and water availability. Current functional trait work focuses on tissue construction and nutrient concentrations, but plant performance in low resource environments also may be strongly influenced by traits related to nutrient budgets and allocation. Our overall objective was to compare trait responses in a suite of serpentine and nonserpentine congener pairs from the California chaparral, a biodiverse region facing nutrient deposition and future changes in precipitation. In a common garden greenhouse environment, we grew small plants of Arctostaphylos manzanita, A. viscida, Ceanothus cuneatus, C. jepsonii, Quercus berberidifolia, and Q. durata in contrasting soil nutrient and moisture treatments. We measured a suite of traits representing physiological, growth, and mineral nutrient responses to these treatments. Overall, plant growth rate and leaf-level phosphorus use efficiency were greatest in the low water, high nutrient treatment, and lowest in the high water, low nutrient treatment. Variation in growth rate and plasticity among species and treatments was primarily associated with differences in mineral nutrition-based traits as opposed to differences in biomass allocation or specific leaf area. Namely, faster growing species and species with greater plasticity allocated more nitrogen and phosphorous to leaves and demonstrated greater photosynthetic phosphorus use efficiency. Overall, nonserpentine species had greater plasticity and biomass response to resource addition than serpentine species, and congener pairs responded to these resource additions more similarly to each other than species across congener pairs. This study extends our general understanding of how functional traits may influence species responses to environmental change and highlights the need to integrate mineral nutrition-based traits, including allocation of nutrient pools and nutrient use efficiency into this larger trait framework. Ultimately, this insight can help identify, in part, why coexisting species may vary in sensitivity to anthropogenic driven changes in soil resource availability.

Do key dimensions of seed and seedling functional trait variation capture variation in recruitment probability?

Seedling recruitment is a critical driver of population dynamics and community assembly, yet we know little about functional traits that define different recruitment strategies. For the first time, we examined whether trait relatedness across germination and seedling stages allows the identification of general recruitment strategies which share core functional attributes and also correspond to recruitment outcomes in applied settings. We measured six seed and eight seedling traits (lab- and field-collected, respectively) for 47 varieties of dryland grasses and used principal component analysis (PCA) and cluster analysis to identify major dimensions of trait variation and to isolate trait-based recruitment groups, respectively. PCA highlighted some links between seed and seedling traits, suggesting that relative growth rate and root elongation rate are simultaneously but independently associated with seed mass and initial root mass (first axis), and with leaf dry matter content, specific leaf area, coleoptile tissue density and germination rate (second axis). Third and fourth axes captured separate tradeoffs between hydrothermal time and base water potential for germination, and between specific root length and root mass ratio, respectively. Cluster analysis separated six recruitment types along dimensions of germination and growth rates, but classifications did not correspond to patterns of germination, emergence or recruitment in the field under either of two watering treatments. Thus, while we have begun to identify major threads of functional variation across seed and seedling stages, our understanding of how this variation influences demographic processes-particularly germination and emergence-remains a key gap in functional ecology.

Prevalence of Low Bone Mineral Density in Younger Versus Older Women With Distal Radius Fractures.

Although distal radius fractures (DRFs) are the most common fractures among younger women, few studies have examined bone health in this age group. We compared bone mineral density (BMD) of younger women (35-50 years) and older women (>50 years) treated for DRFs. Between January 2005 and August 2010, our orthopedic service obtained dual-energy x-ray absorptiometry scans from 128 women with DRFs (47 were 35-50 years old; 81 were older than 50 years). According to the World Health Organization classification system, 43% of the younger patients were osteopenic, and 6% were osteoporotic. Mean femoral neck BMD was 0.91 for the younger group and 0.80 for the older group (P < .05); t scores were -0.87 and -1.65, respectively (P < .05). The difference in femoral neck z scores between the younger and older patients was not statistically different: -0.69 and -0.67, respectively (P = .92). A notable proportion of younger patients with DRFs have osteopenia or osteoporosis. The similarity in z scores among younger and older women with DRFs and among patient groups differentiated by mechanism of injury suggests that any younger or older woman with a DRF should have her BMD evaluated and treated as appropriate.

Residual Hole Orientation After Plate Removal: Effect on the Clavicle.

Clavicle fractures account for 2.6% to 4% of all fractures. Surgical stabilization of this type of injury is becoming more common. Anterior inferior plating and superior plating are 2 popular approaches to open reduction and internal fixation. Reports of plate removal have raised concerns about reinjury. The goal of the current study was to determine whether the orientation of screw holes in clavicles after removal of an anterior inferior plate vs a superior plate have different biomechanical effects on stiffness and load to failure. The medial and lateral ends of 28 matched pairs of fresh clavicles were potted. Pilot holes, 2.5 mm in diameter, were drilled and oriented anterior inferiorly or superiorly, simulating those left after removal of a plate for a middle-third fracture. The clavicles underwent dynamic axial compression and 3-point load to failure, replicating forces associated with reinjury. Clavicles with anterior inferior holes had a statistically significant higher median maximal load difference of 139 N compared with those with superior holes (P=.013). Anterior inferior holes showed a statistically significant median increase in stiffness of 16.3 N/mm compared with superior holes (P=.036). Clavicles with anterior inferior holes had a statistically significant increase in median maximal load to failure and an increase in median stiffness compared with those with superior holes. This finding is relevant for patients who undergo hardware removal and return to activities that put them at risk for repeat high-impact injuries to the clavicle.

Altered snowfall and soil disturbance influence the early life stage transitions and recruitment of a native and invasive grass in a cold desert.

Climate change effects on plants are expected to be primarily mediated through early life stage transitions. Snowfall variability, in particular, may have profound impacts on seedling recruitment, structuring plant populations and communities, especially in mid-latitude systems. These water-limited and frequently invaded environments experience tremendous variation in snowfall, and species in these systems must contend with harsh winter conditions and frequent disturbance. In this study, we examined the mechanisms driving the effects of snowpack depth and soil disturbance on the germination, emergence, and establishment of the native Pseudoroegnaria spicata and the invasive Bromus tectorum, two grass species that are widely distributed across the cold deserts of North America. The absence of snow in winter exposed seeds to an increased frequency and intensity of freeze-thaw cycles and greater fungal pathogen infection. A shallower snowpack promoted the formation of a frozen surface crust, reducing the emergence of both species (more so for P. spicata). Conversely, a deeper snowpack recharged the soil and improved seedling establishment of both species by creating higher and more stable levels of soil moisture availability following spring thaw. Across several snow treatments, experimental disturbance served to decrease the cumulative survival of both species. Furthermore, we observed that, regardless of snowpack treatment, most seed mortality (70-80%) occurred between seed germination and seedling emergence (November-March), suggesting that other wintertime factors or just winter conditions in general limited survival. Our results suggest that snowpack variation and legacy effects of the snowpack influence emergence and establishment but might not facilitate invasion of cold deserts.

Adjustment of suboptimally placed lumbar pedicle screws decreases pullout strength and alters biomechanics of the construct: a pilot cadaveric study.

BACKGROUND: Lumbar pedicle screws are placed for internal fixation and help to enhance bony fusion. Optimal screws are medially directed, should be parallel or pointing to the superior endplate, and penetrate 50%-80% of the vertebral body. "Nonparallel" pedicle screws can be inadvertently placed within the confines of the pedicle and vertebral body but are sometimes replaced to obtain a more acceptable postoperative image. A nonparallel (suboptimal) screw is one that is located within the pedicle and body and does not violate bone; however, it is not parallel to the superior endplate. These "cored-out" grooves left in the bone from the initial tap and screw placement may compromise the integrity of the bone and the construct. METHODS: Dual-energy x-ray absorptiometry scans and L4-5 laminectomies were performed on 6 fresh-frozen cadaveric lumbar spines. We placed 2 optimal pedicle screws in L4, 1 optimal screw in L5, and 1 suboptimal screw in L5 (construct A). Axial rotation, flexion/extension, and lateral bending were tested. The suboptimal screw was repositioned in an optimal trajectory and retested (construct B). Pullout strength was performed on optimal and revised L5 pedicle screws. RESULTS: The mean axial rotation stiffness was 1.31 N-m/degrees ± 0.22 in construct A and 1.19 N-m/degrees ± 0.17 in construct B (P = 0.023; 95% CI [CI], 0.20-0.02). The mean lateral bending stiffness was 0.015 N/mm ± 0.002 in construct A and 0.016 N/mm ± 0.002 in construct B (P = 0.3; 95% CI, 0.0008-0.001). The mean flexion/extension stiffness was 0.0139 N/mm ± 0.002 in construct A and 0.0126 N/mm ± 0.002 in construct B (P = 0.01; 95% CI, 0.002-0.0004). Axial rotation and flexion/extension stiffness were significantly different between the 2 groups. The mean pullout strength was significantly higher in the nonrevised parallel screw group compared with the reimplanted parallel screw group (906.93 N ± 271.17 vs. 608.32 N ± 207.23, P = 0.031). Dual-energy x-ray absorptiometry imaging demonstrated 4 osteopenic and 2 osteoporotic specimens, although differences in bone mineral density did not play a significant role in assessing either the biomechanical parameters or the pullout strength. CONCLUSIONS: Great care is warranted in the initial placement of lumbar pedicle screws. Revising a nonparallel screw placement decreases pullout strength and alters biomechanical movements (axial rotation and flexion/extension) in patients with decreased bone mineral density. If a screw is inadvertently placed nonparallel to the endplate but is within the confines of the pedicle and vertebral body with adequate bone purchase, it should not be revised and rather be left in its place.

A new perspective on trait differences between native and invasive exotic plants.

Functional differences between native and exotic species potentially constitute one factor responsible for plant invasion. Differences in trait values between native and exotic invasive species, however, should not be considered fixed and may depend on the context of the comparison. Furthermore, the magnitude of difference between native and exotic species necessary to trigger invasion is unknown. We propose a criterion that differences in trait values between a native and exotic invasive species must be greater than differences between co-occurring natives for this difference to be ecologically meaningful and a contributing factor to plant invasion. We used a meta-analysis to quantify the difference between native and exotic invasive species for various traits examined in previous studies and compared this value to differences among native species reported in the same studies. The effect size between native and exotic invasive species was similar to the effect size between co-occurring natives except for studies conducted in the field; in most instances, our criterion was not met although overall differences between native and exotic invasive species were slightly larger than differences between natives. Consequently, trait differences may be important in certain contexts, but other mechanisms of invasion are likely more important in most cases. We suggest that using trait values as predictors of invasion will be challenging.

Prevalence of hypovitaminosis D among children with upper extremity fractures.

BACKGROUND: Recent publications show a high rate of hypovitaminosis D among children in general as well as among children with fractures. 25-hydroxyvitamin D levels were analyzed from hospital records to determine the prevalence of hypovitaminosis D, with the goal of using that information in fracture management and nutritional counseling. METHODS: We retrospectively reviewed the records of 213 children with upper extremity fractures that were treated during a 14-month period. For 181 of those patients, the 25-hydroxyvitamin D level was measured at the time of emergency department presentation or at the first clinic appointment within 2 weeks after the initial presentation. The following information was collected from the charts: fracture mechanism (high or low energy), age, sex, race, and body mass index. Vitamin D levels were categorized as normal (≥ 32 ng/mL), insufficient (20 to 32 ng/mL), or deficient (< 20 ng/mL). The levels were analyzed with respect to fracture pattern and race. RESULTS: Of the 181 patients, 24% had deficient vitamin D levels, 41% had insufficient levels, and 35% had normal levels. There was no significant correlation with vitamin D level and mechanism of injury. African American children were more likely to have insufficient or deficient levels of vitamin D. CONCLUSIONS: Hypovitaminosis D is common among children with upper extremity fractures. Further investigation is warranted on the use of the 25-hydroxyvitamin D level as a screening tool to predict risk of fracture and to design proper nutritional programs for children with fractures. LEVEL OF EVIDENCE: Retrospective chart review; Level III evidence.

Temperature and functional traits influence differences in nitrogen uptake capacity between native and invasive grasses.

Performance differences between native and exotic invasive plants are often considered static, but invasive grasses may achieve growth advantages in western North America shrublands and steppe under only optimal growing conditions. We examine differences in N uptake and several morphological variables that influence uptake at temperatures between 5 and 25 °C. We contrast two native perennial grasses in western North America: Elymus elymoides and Pseudoroegneria spicata; two invasive annual grasses: Bromus tectorum and Taeniatherum caput-medusae; and one highly selected non-native perennial grass: Agropyron cristatum. The influence of temperature on N uptake is poorly characterized, yet these invasive annual grasses are known to germinate in warm soils in the autumn, and both experience cool soils during the short growing season following snowmelt in the spring. To further explore the influence of temperature on the correlation between morphological variables and N uptake, our data are applied to a previously published path model and one proposed here. Differences in N uptake between native and invasive grasses were small at the lowest temperature, but were large at the highest temperature. At lower temperatures, uptake of N by annuals and perennials was correlated with leaf N and mass. At higher temperatures, uptake by annuals was correlated only with these leaf traits, but uptake by perennials was correlated with these leaf traits as well as root N and mass. Consequently, our results imply that annual grasses face fewer morphological constraints on N uptake than perennial grasses, and annual grasses may gain further advantage in warmer temperature conditions or during more frequent warm periods.

A functional trait perspective on plant invasion.

BACKGROUND AND AIMS: Global environmental change will affect non-native plant invasions, with profound potential impacts on native plant populations, communities and ecosystems. In this context, we review plant functional traits, particularly those that drive invader abundance (invasiveness) and impacts, as well as the integration of these traits across multiple ecological scales, and as a basis for restoration and management. SCOPE: We review the concepts and terminology surrounding functional traits and how functional traits influence processes at the individual level. We explore how phenotypic plasticity may lead to rapid evolution of novel traits facilitating invasiveness in changing environments and then 'scale up' to evaluate the relative importance of demographic traits and their links to invasion rates. We then suggest a functional trait framework for assessing per capita effects and, ultimately, impacts of invasive plants on plant communities and ecosystems. Lastly, we focus on the role of functional trait-based approaches in invasive species management and restoration in the context of rapid, global environmental change. CONCLUSIONS: To understand how the abundance and impacts of invasive plants will respond to rapid environmental changes it is essential to link trait-based responses of invaders to changes in community and ecosystem properties. To do so requires a comprehensive effort that considers dynamic environmental controls and a targeted approach to understand key functional traits driving both invader abundance and impacts. If we are to predict future invasions, manage those at hand and use restoration technology to mitigate invasive species impacts, future research must focus on functional traits that promote invasiveness and invader impacts under changing conditions, and integrate major factors driving invasions from individual to ecosystem levels.

Trait convergence and plasticity among native and invasive species in resource-poor environments.

PREMISE OF STUDY: Functional trait comparisons provide a framework with which to assess invasion and invasion resistance. However, recent studies have found evidence for both trait convergence and divergence among coexisting dominant native and invasive species. Few studies have assessed how multiple stresses constrain trait values and plasticity, and no study has included direct measurements of nutrient conservation traits, which are critical to plants growing in low-resource environments. METHODS: We evaluated how nutrient and water stresses affect growth and allocation, water potential and gas exchange, and nitrogen (N) allocation and use traits among a suite of six codominant species from the Intermountain West to determine trait values and plasticity. In the greenhouse, we grew our species under a full factorial combination of high and low N and water availability. We measured relative growth rate (RGR) and its components, total biomass, biomass allocation, midday water potential, photosynthetic rate, water-use efficiency (WUE), green leaf N, senesced leaf N, total N pools, N productivity, and photosynthetic N use efficiency. KEY RESULTS: Overall, soil water availability constrained plant responses to N availability and was the major driver of plant trait variation in our analysis. Drought decreased plant biomass and RGR, limited N conservation, and led to increased WUE. For most traits, native and nonnative species were similarly plastic. CONCLUSIONS: Our data suggest native and invasive biomass dominants may converge on functionally similar traits and demonstrate comparable ability to respond to changes in resource availability.

Microsite and herbaceous vegetation heterogeneity after burning Artemisia tridentata steppe.

Woody vegetation can create distinct subcanopy and interspace microsites, which often result in resource islands in subcanopies compared to interspaces. This heterogeneity in soil resources contributes to herbaceous vegetation heterogeneity in plant communities. However, information detailing the impact of disturbance, such as fire, that removes the woody vegetation on microsites and herbaceous vegetation heterogeneity is limited. The purpose of this study was to determine the influence of burning on microsites and herbaceous vegetation in subcanopies and interspaces. Six study sites (blocks) were located at the Northern Great Basin Experimental Range in shrub (Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh)-bunchgrass plant communities and one half of each block was burned to remove A. tridentata. Herbaceous vegetation and microsite characteristics were measured 2 years post-fire in intact and burned subcanopies and interspaces. Burning resulted in microsite and herbaceous vegetation differences between intact and burned subcanopies and intact and burned interspaces. However, burned subcanopies and burned interspaces appeared to be relatively similar. The similarity in microsite characteristics probably explains the lack of differences in herbaceous vegetation cover and biomass production between burned subcanopies and burned interspaces (P > 0.05). However, some microsite and herbaceous vegetation characteristics differed between burned subcanopies and burned interspaces. Our results suggest that disturbances that remove woody vegetation reduced microsite and herbaceous vegetation heterogeneity within plant communities, but do not completely remove the resource island effect. This suggests soil resource heterogeneity may influence post-fire community assembly and contribute to diversity maintenance.

Environmental stress and genetics influence night-time leaf conductance in the C4 grass Distichlis spicata.

Growing awareness of night-time leaf conductance (gnight) in many species, as well as genetic variation in gnight within several species, has raised questions about how genetic variation and environmental stress interact to influence the magnitude of gnight. The objective of this study was to investigate how genotype salt tolerance and salinity stress affect gnight for saltgrass [Distichlis spicata (L.) Greene]. Across genotypes and treatments, night-time water loss rates were 5-20% of daytime rates. Despite growth declining 37-87% in the high salinity treatments (300 mm and 600 mm NaCl), neither treatment had any effect on gnight in four of the six genotypes compared with the control treatment (7 mm NaCl). Daytime leaf conductance (gday) also was not affected by salinity treatment in three of the six genotypes. There was no evidence that more salt tolerant genotypes (assessed as ability to maintain growth with increasing salinity) had a greater capacity to maintain gnight or gday at high salinity. In addition, gnight as a percentage of gday was unaffected by treatment in the three most salt tolerant genotypes. Although gnight in the 7 mm treatment was always highest or not different compared with the 300 mm and 600 mm treatments, gday was generally highest in the 300 mm treatment, indicating separate regulation of gnight and gday in response to an environmental stress. Thus, it is clear that genetics and environment both influence the magnitude of gnight for this species. Combined effects of genetic and environmental factors are likely to impact our interpretation of variation of gnight in natural populations.

Variation in resource acquisition and utilization traits between native and invasive perennial forbs.

Understanding the functional traits that allow invasives to outperform natives is a necessary first step in improving our ability to predict and manage the spread of invaders. In nutrient-limited systems, plant competitive ability is expected to be closely tied to the ability of a plant to exploit nutrient-rich microsites and use these captured nutrients efficiently. The broad objective of this work was to compare the ability of native and invasive perennial forbs to acquire and use nutrients from nutrient-rich microsites. We evaluated morphological and physiological responses among four native and four invasive species exposed to heterogeneous (patch) or homogeneous (control) nutrient distribution. Invasives, on average, allocated more biomass to roots and allocated proportionately more root length to nutrient-rich microsites than did natives. Invasives also had higher leaf N, photosynthetic rates, and photosynthetic nitrogen use efficiency than natives, regardless of treatment. While these results suggest multiple traits may contribute to the success of invasive forbs in low-nutrient environments, we also observed large variation in these traits among native forbs. These observations support the idea that functional trait variation in the plant community may be a better predictor of invasion resistance than the functional group composition of the plant community.