One leg testing in hip and knee osteoarthritis: A comparison with a two-leg oriented functional outcome measure and self-reported functional measures.

OBJECTIVE: To compare the responsiveness of two unilateral lower-limb performance-based tests, the one-leg rise test and the maximal step-up test, with the bilateral 30-second chair-stand test and the self-reported measure of physical function (HOOS/KOOS). Specific aims were to evaluate responsiveness, floor/ceiling effect and association between the instruments. METHOD: Data was included from 111 participants, mean age 61.3 years (8.3), with clinically verified hip or knee osteoarthritis, who reported less than 150 minutes/week of moderate or vigorous intensity physical activity. Responsiveness, how well the instruments captured improvements, was measured as Cohen's standardised mean difference for effect size, and was assessed from baseline to 12 months following a physical activity intervention. Other assessments were floor and ceiling effects, and correlations between tests. RESULTS: The maximal step-up test had an effect size of 0.57 (95% CI 0.37, 0.77), the 30-second chair-stand 0.48 (95% CI 0.29, 0.68) and the one-leg rise test 0.12 (95% CI 0.60, 0.31). The one-leg rise test had a floor effect as 72% of the participants scored zero at baseline and 63% at 12 months. The correlation between performance-based tests and questionnaires was considered to be minor (r = 0.188 to 0.226) (p = 0.018 to 0.048). CONCLUSION: The unilateral maximal step-up test seems more responsive to change in physical function compared to the bilateral 30-second chair-stand test, although the tests did not differ statistically in effect size. The maximal step-up test provides specific information about each leg for the individual and allows for comparison between the legs.

Arena surface vertical impact forces vary with surface compaction.

Mechanical properties of arena surfaces are extrinsic factors for musculoskeletal injury. Vertical impact forces of harrowed and compacted cushion were measured at five locations on 12 arena surfaces (five dirt, seven synthetic [dirt and fiber]). Eight variables related to impact force, displacement, and acceleration were calculated. Surface temperature, cushion depth and moisture content were also measured. The effects of surface material type (dirt/synthetic) and cushion compaction (harrowed/compacted) on vertical impact properties were assessed using an analysis of variance. Relationships of manageable surface properties with vertical impact forces were examined through correlations. Compacted cushion exhibited markedly higher vertical impact force and deceleration with lower vertical displacement than harrowed cushion (P < 0.001), and the effect was greater on dirt than synthetic surfaces (P = 0.039). Vertical displacement (P = 0.021) and soil rebound (P = 0.005) were the only variables affected by surface type. Surface compaction (harrowed, compacted) had a significantly greater effect on vertical impact forces than surface type (dirt, synthetic). By reducing surface compaction through harrowing, extrinsic factors related to musculoskeletal injury risk are reduced. These benefits were more pronounced on dirt than synthetic surfaces. These results indicate that arena owners should regularly harrow surfaces, particularly dirt surfaces.

Shear ground reaction force variation among equine arena surfaces.

Shear forces at the surface-hoof interface affect hoof slide, surface grip, forces transferred to the limb, and injury risk. However, the variation in shear forces among surfaces with different compositions have not been quantified. Shear ground reaction forces were measured on five dirt and seven synthetic arena surfaces. Cohesion/adhesion and angle of internal friction/coefficient of friction were calculated. Surface composition, surface temperature, cushion depth, and moisture content were also measured. The effects of surface material (dirt/synthetic) on shear properties were assessed using analysis of variance (ANOVA; P < 0.05). The relationships between surface composition or management properties and shear properties were analyzed using linear correlation. Shear properties were not different between dirt and synthetic surface categories; however, surface fiber content was correlated with adhesion and coefficient of friction. These correlations predict that more fiber will decrease soil adhesion (r = -0.75; P < 0.01) and increase the coefficient of friction (r = 0.81; P < 0.01). Furthermore, maximum shear force was significantly correlated with cushion depth (r = 0.61; P < 0.01) and moisture content (r = 0.57; P < 0.01), where shear force was greater on surfaces with thicker cushion layers or higher moisture content. The findings suggest that shear mechanical behavior is more dependent on surface composition than surface material categories (dirt/synthetic) and also indicate that arena owners can influence shear forces by adjusting either surface composition or management.

Self-reported participation in outdoor and nature-based recreation before and during the COVID-19 pandemic supports psychological health and well-being.

Restrictions associated with the COVID-19 pandemic significantly altered daily lives and affected human health and well-being. Outdoor and nature-based activities could potentially mitigate some of these negative impacts. To assess the impact of the COVID-19 pandemic on outdoor recreation and subjective well-being, we combined two samples of U.S. adults collected from April 30th - June 15th, 2020 and from August 7th - August 26th, 2020 (total n = 2178) using Qualtrics XM. During the pandemic, participation in outdoor activities declined by 35%, participation in nature-based activities declined by 33%, and subjective well-being declined by 24%. Participation in outdoor activities and nature activities prior to the pandemic and during the pandemic predicted smaller declines in subjective well-being. Results highlight the importance of outdoor recreation for building resilience to changes in subjective well-being before and during global crises like the COVID-19 pandemic.

Political polarization of conservation issues in the era of COVID-19: An examination of partisan perspectives and priorities in the United States.

As a zoonotic disease with unprecedented global impacts, COVID-19 may influence how people prioritize issues related to wildlife conservation. Using a nationally representative sample of US residents, we investigated: (1) how COVID-19 affected the relative importance of conservation issues among adults with different political ideologies, and (2) how the pandemic affected political polarization of conservation issues during the 2020 general election in the United States. Conservation issues such as endangered species and controlling zoonotic disease ranked low in importance among the 14 policy issues considered, even lower than environmental issues such as climate change and environmental protection; however, the importance of all conservation issues increased as a result of COVID-19. Political polarization surrounding the perceived importance of conservation issues also increased during the COVID-19 pandemic, with Democrats reporting larger increases in importance than Republicans. Polarization was driven by the most conservative Republicans and the most liberal Democrats. But this polarization was less extreme than it was for other issues such as climate change and healthcare. Findings highlight the need for communicating links between zoonotic disease and human interactions with wildlife and the environment. Acting quickly may be critical in areas where conservation issues are primed to succumb to political polarization.

Complications associated with paediatric airway management during the COVID-19 pandemic: an international, multicentre, observational study.

Respiratory adverse events in adults with COVID-19 undergoing general anaesthesia can be life-threatening. However, there remains a knowledge gap about respiratory adverse events in children with COVID-19. We created an international observational registry to collect airway management outcomes in children with COVID-19 who were having a general anaesthetic. We hypothesised that children with confirmed or suspected COVID-19 would experience more hypoxaemia and complications than those without. Between 3 April 2020 and 1 November 2020, 78 international centres participated. In phase 1, centres collected outcomes on all children (age ≤ 18 y) having a general anaesthetic for 2 consecutive weeks. In phase 2, centres recorded outcomes for children with test-confirmed or suspected COVID-19 (based on symptoms) having a general anaesthetic. We did not study children whose tracheas were already intubated. The primary outcome was the incidence of hypoxaemia during airway management. Secondary outcomes included: incidence of other complications; and first-pass success rate for tracheal intubation. In total, 7896 children were analysed (7567 COVID-19 negative and 329 confirmed or presumed COVID-19 positive). The incidence of hypoxaemia during airway management was greater in children who were COVID-19 positive (24 out of 329 (7%) vs. 214 out of 7567 (3%); OR 2.70 (95%CI 1.70-4.10)). Children who had symptoms of COVID-19 had a higher incidence of hypoxaemia compared with those who were asymptomatic (9 out of 51 (19%) vs. 14 out of 258 (5%), respectively; OR 3.7 (95%CI 1.5-9.1)). Children with confirmed or presumed COVID-19 have an increased risk of hypoxaemia during airway management in conjunction with general anaesthesia.

Retroperitoneal Fat Necrosis in Response to an Episode of Acute Pancreatitis.

Acute pancreatitis can result in fat necrosis, typically occurring in the peripancreatic region within weeks to months, and it generally appears as a low attenuation collection, with minimal heterogeneity. There are no specific imaging features that can diagnose retroperitoneal fat necrosis which may imitate other entities including certain malignancies, which may lead to invasive studies for diagnosis. Herein, we present a case of extensive retroperitoneal fat necrosis beyond the peripancreatic region that developed 10 days after an episode of acute pancreatitis.

Intergenerational learning: A recommendation for engaging youth to address marine debris challenges.

Youth can impact environmental attitudes and behaviors among adults. Indeed, research on intergenerational learning has demonstrated the influence of young people on adults in their lives for myriad environmental topics. Intergenerational learning (IGL) refers to the bidirectional transfer of knowledge, attitudes, or behaviors from children to their parents or other adults and vice versa. We suggest an educational framework wherein K-12 marine debris education designed to maximize IGL may be a strategy to accelerate interdisciplinary, community-level solutions to marine debris. Although technical strategies continue to be developed to address the marine debris crisis, even the most strictly technical of these benefit from social support. Here, we present 10 Best Practices grounded in educational, IGL, and youth civic engagement literature to promote marine debris solutions. We describe how integrating IGL and civic engagement into K-12-based marine debris curricula may start a virtuous circle benefiting teachers, students, families, communities, and the ocean.

Natural and anthropogenic sources of habitat variation influence exploration behaviour, stress response, and brain morphology in a coastal fish.

Evolutionary ecology aims to better understand how ecologically important traits respond to environmental heterogeneity. Environments vary both naturally and as a result of human activities, and investigations that simultaneously consider how natural and human-induced environmental variation affect diverse trait types grow increasingly important as human activities drive species endangerment. Here, we examined how habitat fragmentation and structural habitat complexity affect disparate trait types in Bahamas mosquitofish Gambusia hubbsi inhabiting tidal creeks. We tested a priori predictions for how these factors might influence exploratory behaviour, stress reactivity and brain anatomy. We examined approximately 350 adult Bahamas mosquitofish from seven tidal-creek populations across Andros Island, The Bahamas that varied in both human-caused fragmentation (three fragmented and four unfragmented) and natural habitat complexity (e.g. fivefold variation in rock habitat). Populations that had experienced severe human-induced fragmentation, and thus restriction of tidal exchange from the ocean, exhibited greater exploration of a novel environment, stronger physiological stress responses to a mildly stressful event and smaller telencephala (relative to body size). These changes matched adaptive predictions based mostly on (a) reduced chronic predation risk and (b) decreased demands for navigating tidally dynamic habitats. Populations from sites with greater structural habitat complexity showed a higher propensity for exploration and a relatively larger optic tectum and cerebellum. These patterns matched adaptive predictions related to increased demands for navigating complex environments. Our findings demonstrate environmental variation, including recent anthropogenic impacts (<50 years), can significantly affect complex, ecologically important traits. Yet trait-specific patterns may not be easily predicted, as we found strong support for only six of 12 predictions. Our results further highlight the utility of simultaneously quantifying multiple environmental factors-for example had we failed to account for habitat complexity, we would not have detected the effects of fragmentation on exploratory behaviours. These responses, and their ecological consequences, may be complex: rapid and adaptive phenotypic responses to anthropogenic impacts can facilitate persistence in human-altered environments, but may come at a cost of population vulnerability if ecological restoration was to occur without consideration of the altered traits.

Outdoor Activity Participation Improves Adolescents' Mental Health and Well-Being during the COVID-19 Pandemic.

COVID-19 is reshaping human interactions with the natural environment, potentially generating profound consequences for health and well-being. To assess the effects of COVID-19 on the outdoor recreation participation and subjective well-being of adolescents, as well as how participation in outdoor activities may mitigate declines in subjective well-being, we used a Qualtrics XM panel to conduct a nationally representative survey of youth ages 10-18 across the United States (n = 624) between 30 April and 15 June 2020. Survey questions focused on frequency of participation in outdoor activities before and during the pandemic, as well as changes in subjective well-being. Paired t-tests revealed decreases in both outdoor recreation participation (64% reported declines) and subjective well-being (52% reported declines). A regression model examining correlates of changes in subjective well-being (R2 = 0.42) revealed strong associations with changes in outdoor play (B = 0.44, p < 0.001) and nature-based (B = 0.21, p = 0.016) activities. Adolescents' from all backgrounds who participated in these activities during the pandemic reported smaller declines in subjective well-being. Results highlight the critical role that time outdoors and time in nature play in bolstering adolescents' resilience to stressors such as the COVID-19 pandemic and underscore the need to facilitate outdoor recreation opportunities for youth during times of crisis.

A Chemo-poroelastic Analysis of Mechanically Induced Fluid and Solute Transport in an Osteonal Cortical Bone.

It is well known that transport of nutrients and wastes as solute in bone fluid plays an important role in bone remodeling and damage healing. This work presents a chemo-poroelastic model for fluid and solute transport in the lacunar-canalicular network of an osteonal cortical bone under cyclic axial mechanical loading or vascular pressure. Analytical solutions are obtained for the pore fluid pressure, and fluid and solute velocities. Numerical results for fluid and calcium transport indicate that under a cyclic stress of 20 MPa, the magnitudes of the fluid and calcium velocities increase with an increase in the loading frequency for the frequency range considered (≤ 3 Hz) and peak at the inner boundary. The peak magnitude of calcium velocity reaches 18.9 µm/s for an osteon with a permeability of 1.5 × 10-19 m2 under a 3 Hz loading frequency. The magnitude of calcium velocity under a vascular pressure of 50 mmHg is found to be two orders of magnitude smaller than that under the mechanical load. These results have the potential to be important in understanding fundamental aspects of cortical bone remodeling as transport characteristics of calcium and other nutrients at the osteon scale influence bone metabolism.

Predicting soil pH changes in response to application of urea and sheep urine.

Volatilization of NH3 following urea application or livestock urine deposition can result in significant loss of N to the environment. Urea hydrolysis to NH4 + results in an increase in pH, which in turn promotes transformation of NH4 + to NH3 . Accurately predicting changes in soil pH following urea (or urine) application will allow successful simulation of NH3 volatilization. The magnitude of the pH change depends on the soil's pH buffering capacity (pHBC). However, as actual pHBC values are not generally available, pHBC proxies (e.g., cation exchange capacity) have been used in modeling studies. In a 34-d laboratory incubation study, we measured soil pH and mineral N (NH4 + and NO3 - ) following a large application of urea (800 mg N kg-1 soil) to four soils with a range of pHBC values. In a second incubation, pH changes and mineral N dynamics were monitored in soil treated with sheep urine (773 mg N kg-1 soil) in the absence and presence of the nitrification inhibitor dicyandiamide. In both incubations, pH changes associated with urea hydrolysis and subsequent nitrification of NH4 + were predicted well using measured pHBC data. Our results confirmed that pHBC is base-type dependent (values greater when measured using KOH than NH4 OH). Soil pHBC is easily measured, and the use of a measured value (determined using NH4 OH) can improve model simulations of pH in the field and, potentially, lead to improved estimates of NH3 loss from animal-deposited urine patches and urea-treated soil.

Medical care of adults with Down Syndrome a clinical guideline

Down syndrome is the most common chromosomal condition, and average life expectancy has increased substantially, from 25 years in 1983 to 60 years in 2020. Despite the unique clinical comorbidities among adults with Down syndrome, there are no clinical guidelines for the care of these patients. To develop an evidence-based clinical practice guideline for adults with Down syndrome. The Global Down Syndrome Foundation Medical Care Guidelines for Adults with Down Syndrome Workgroup (n = 13) developed 10 Population/Intervention/ Comparison/Outcome (PICO) questions for adults with Down syndrome addressing multiple clinical areas including mental health (2 questions), dementia, screening or treatment of diabetes, cardiovascular disease, obesity, osteoporosis, atlantoaxial instability, thyroid disease, and celiac disease. These questions guided the literature search in MEDLINE, EMBASE, PubMed, PsychINFO, Cochrane Library, and the TRIP Database, searched from January 1, 2000, to February 26, 2018, with an updated search through August 6, 2020. Using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology and the Evidence-to-Decision framework, in January 2019, the 13-member Workgroup and 16 additional clinical and scientific experts, nurses, patient representatives, and a methodologist developed clinical recommendations. A statement of good practice was made when there was a high level of certainty that the recommendation would do more good than harm, but there was little direct evidence. From 11 295 literature citations associated with 10 PICO questions, 20 relevant studies were identified. An updated search identified 2 additional studies, for a total of 22 included studies (3 systematic reviews, 19 primary studies), which were reviewed and synthesized. Based on this analysis, 14 recommendations and 4 statements of good practice were developed. Overall, the evidence base was limited. Only 1 strong recommendation was formulated: screening for Alzheimer-type dementia starting at age 40 years. Four recommendations (managing risk factors for cardiovascular disease and stroke prevention, screening for obesity, and evaluation for secondary causes of osteoporosis) agreed with existing guidance for individuals without Down syndrome. Two recommendations for diabetes screening recommend earlier initiation of screening and at shorter intervals given the high prevalence and earlier onset in adults with Down syndrome. These evidence-based clinical guidelines provide recommendations to support primary care of adults with Down syndrome. The lack of high-quality evidence limits the strength of the recommendations and highlights the need for additional research.

Short-term biological variation of serum thyroid hormones concentrations in clinically healthy cats.

Thyroid disease is common in cats, but little is known about the biologic variability of serum thyroid hormone concentrations and its impact on diagnostic utility in either healthy cats or cats with thyroid disease. The purpose of this study was to determine the biological variation, index of individuality, and reference change values for thyroid hormones and thyroid-stimulating hormone (TSH) in clinically healthy cats. Serum samples for analysis of total thyroxine (T4), triiodothyronine (T3), free T4 by dialysis, and TSH were obtained weekly for 6 wk from 10 healthy cats, then frozen until single-batch analyzed. Data were evaluated for outliers, and we determined the CV within individual cats (CVI) and between individual cats (CVG) for each hormone and the variation between duplicates or analytical variation (CVA). The index of individuality and reference change values for each hormone were then calculated. Serum concentrations of total T4, free T4, T3, and TSH all showed greater variation between cats (CVG) than within cats (CVI). Total and free T4 had an intermediate index of individuality (1.1 and 1.2, respectively), suggesting that these hormones would be best evaluated by a combination of their population-based reference intervals and reference change values. Serum TSH concentrations had high index of individuality (1.8), suggesting this hormone would be best evaluated with reference change values rather than the population-based reference interval. Total T3 also had a high calculated index of individuality (1.8); however, T3 had high ratio of analytical variation (CVA) to within cat variation (CVI), so RCV could not be accurately calculated. This study demonstrates that clinically normal cats show considerable interindividual biological variation in serum thyroid hormone and TSH concentrations, whereas the intraindividual variability in hormone concentrations is much narrower. This suggests that for all serum thyroid hormones, but especially serum TSH and T3 concentrations, comparing individual cat's hormone results to a population-based reference interval may be misleading, especially in those with early or subclinical thyroid disease. Clinicians might improve the diagnosis of feline thyroid disease by establishing baseline concentrations of T4, free T4, T3, and TSH for individual cats (ideally when healthy) and applying reference change values to subsequent measurements.

Extensively drug-resistant tuberculosis 'hotspots' and sociodemographic associations in Durban, South Africa.

In KwaZulu-Natal, South Africa, the incidence of extensively drug-resistant tuberculosis (XDR-TB) is driven by the transmission of resistant strains. As data suggest that cases may be spatially clustered, we sought to identify 'hotspots' and describe these communities. We enrolled XDR-TB patients diagnosed from 2011 to 2014 in eThekwini. Global positioning system (GPS) coordinates for participant homes were collected and hotspots were identified based on population-adjusted XDR-TB incidence. The sociodemographic features of hotspots were characterised using census data. For a subset of participants, we mapped non-home XDR-TB congregate locations and compared these with results including only homes. Among 132 participants, 75 (57%) were female and 87 (66%) lived in urban or suburban locations. Fifteen of 197 census tracts were identified as XDR-TB hotspots with ≥95% confidence. Four spatial mapping methods identified one large hotspot in northeastern eThekwini. Hotspot communities had higher proportions of low educational attainment (12% vs. 9%) and unemployment (29.3% vs. 20.4%), and lower proportion of homes with flush toilets (36.4% vs. 68.9%). The case density shifted towards downtown Durban when congregate locations (e.g., workplaces) for 43 (33%) participants were mapped. In eThekwini, XDR-TB case homes were clustered into hotspots with more poverty indicators than non-hotspots. Prevention efforts targeting hotspot communities and congregate settings may be effective in reducing community transmission. .

The Burden of Functional Disabilities for Middle-Aged and Older Adults in the United States.

OBJECTIVES: Understanding the role of functional capacity on longevity is important as the population in the United States ages. The purpose of this study was to determine the burden of instrumental activities of daily living (IADL) and activities of daily living (ADL) disabilities for a nationally-representative sample of middle-aged and older adults in the United States. DESIGN: Longitudinal-Panel. SETTING: Core interviews were often performed in person or over the telephone. PARTICIPANTS: A sub-sample of 31,055 participants aged at least 50 years from the 1998-2014 waves of the Health and Retirement Study who reported having a functional disability were included. MEASUREMENTS: Ability to perform IADLs and ADLs were self-reported at each wave. The National Death Index was used to ascertain date of death. The number of years of life that were lost (YLLs) and years lived with a disability (YLDs) were summed for the calculation of disability-adjusted life years (DALYs). Sampling weights were used in the analyses to make the DALYs nationally-representative. The results for YLLs, YLDs, and DALYs are reported in thousands. RESULTS: Of the participants included, 14,990 had an IADL disability and 13,136 had an ADL disability. Men and women with an IADL disability had 236,037 and 233,772 DALYs, respectively; whereas, there were 178,594 DALYs for males and 253,630 DALYs for females with an ADL disability. Collectively, there were 469,809 years of healthy life lost from IADL impairments, and 432,224 years of healthy life lost from ADL limitations. CONCLUSIONS: These findings should be used to inform healthcare providers and guide interventions aiming to preserve the functional capacity of aging adults. Prioritizing health-related resources for mitigating the burden of functional disabilities may help aging adults increase their quality of life and life expectancy over time.

Educational attainment predicts negative perceptions women have of their own climate change knowledge.

Education may encourage personal and collective responses to climate change, but climate education has proven surprisingly difficult and complex. Self-perception of knowledge and intelligence represent one factor that may impact willingness to learn about climate change. We explored this possibility with a case study in Raleigh, North Carolina in 2015 (n = 200). Our goal was to test how gender and ethnicity influenced perceptions people had of their own climate change knowledge. Survey respondents were asked how strongly they agreed with the statement "I feel knowledgeable about climate change" (1 = strongly disagree, and 5 = strongly agree). Our survey instrument also included demographic questions about race, age, income, gender, and education, as well as respondent's experience with natural disasters and drought. We observed an interaction between education and gender where women's self-perceived knowledge was higher than men among people with low levels of educational attainment, but was higher for men than women among people with high levels of educational attainment. In addition, minority respondents self-reported lower perceived climate change knowledge than white respondents, regardless of educational attainment. This study enhances our understanding of the gender gap in self-perceptions of climate knowledge by suggesting it is contingent on educational attainment. This could be the result of stereotype-threat experienced by women and minorities, and exacerbated by educational systems. Because people who question their knowledge are often more able to learn, particularly in ideologically charged contexts, highly educated women and minorities may be more successful learning about climate change than white men.

Shoot shovel and sanction yourself: Self-policing as a response to wolf poaching among Swedish hunters.

Self-policing is essential for addressing wildlife-related crime where illegal activity is extremely diffuse, and limited resources are available for monitoring and enforcement. Emerging research on self-policing suggest key drivers including economics, folk traditions, and socio-political resistance. We build on this research with a case study evaluating potential drivers of self-policing illegal wolf killing among Swedish hunting teams. Swedish hunters marginally leaned toward considering illegal hunting of wolves an expression of resistance (10.30 out of a possible 17 on a resistance scale) and strongly believed outsiders had undue influence over hunting (15.79 out of a possible 21 on an influence scale). Most (73%) Swedish hunters stated they would report illegal wolf killing to authorities, but 20% stated they would handle the infractions through internal sanctions. Viewing illegal hunting of wolves as a form of political resistance, viewing wolf management as being controlled locally, and perceived prevalence of illegal wolf killing among hunting acquaintances were positive predictors of preferring internal sanctions to address illegal wolf killing over reporting the crimes. Resistance and perceived prevalence of wolf killing also predicted preferring no action to address illegal wolf killing. These results suggest that a counterpublic of marginalized ruralism may promote forms of self-policing that rely on internal censure for illegal wolf killing rather than using formal legal channels. Similarly, folk traditions within this counterpublic (e.g., perceptions of prevalence of illegal wolf killing) shape if and how internal sanctions are advocated. Re-engaging marginalized hunting groups and emphasizing the rarity of illegal wolf killing may promote wolf conservation, both in Sweden and in other democratic regimes.

Feedback effect of crop raiding in payments for ecosystem services.

Payments for ecosystem services (PES) may alter dynamics in coupled human and natural systems, producing reciprocal feedback effects on socioeconomic and environmental outcomes. As forests recover following China's two nation-wide PES programs, wildlife-related crop raiding has been increasingly affecting rural people's livelihoods. We evaluate the feedback effect of crop raiding on people's intention to convert their cropland plots into forests under different PES program scenarios in the Tianma National Nature Reserve. Increases in crop raiding, conservation payment amounts, and program duration significantly increased local people's intention to enroll their cropland plots in future PES programs. Our results suggest that a substantial portion of economic benefit from the current PES programs was offset by the feedback effect of crop raiding promoted by these programs. Therefore, such complex human-environment interactions should be incorporated into the design and evaluation of China's PES practices and other PES programs around the world.