•The review indicates that bamboo forests are efficient and effective carbon sinks.•Bamboo land covers also provide other ecosystem services and livelihood benefits.•Sustainable use of bamboo can ...help to supplement the livelihoods of millions of rural people worldwide.•In some settings bamboo may have negative environmental impacts that offset the positive benefits.•Bamboo should be managed with an ecosystem perspective that considers major social-ecological interactions.
From a review of 184 studies on bamboo biomass for 70 species (22 genera) we estimate plausible ranges for above-ground carbon (AGC) biomass (16–128MgC/ha), below-ground carbon (BGC) biomass (8–64MgC/ha), soil organic carbon (SOC; 70–200MgC/ha), and total ecosystem carbon (TEC; 94–392MgC/ha). The total ecosystem carbon range is below that for most types of forests, on par with that of rubber plantations and tree orchards, but greater than agroforests, oil palm, various types of swidden fallows, grasslands, shrublands, and pastures. High carbon biomass was associated with many Phyllostachys spp., including Moso (P. edulis) in China, Japan, Taiwan, and Korea, as well as other “giant” bamboo species of genera Bambusa, Dendrocalamus, Gigantochloa, and Guadua. The low end of the TEC range for mature bamboo typically included various species of dwarf bamboo, understory species, and stands stressed by climatic factors (temperature, rainfall), soil conditions, and management practices. Limited research and uncertainties associated with determinations prevent a robust assessment of carbon stocks for most species. Moso bamboo was by far the most studied species (>40% of the reported values), as it is commonly grown in plantations for commercial use. Similarly, a review of available allometric equations revealed that more work is needed to develop equations for predicting carbon biomass for most species. Most allometry equations exist for AGC for China, where 33 species have been studied. Allometric equations for BGC are rare, with all work conducted in China (15 species) and India (2). Root:shoot ratio estimate for most groups of species and genera were less than one, with the exception of Phyllostachys spp (however, some individual species with small sample size were greater than one).
Estimated annual carbon accumulation rates were on the order of 8–14MgC/ha, relaxing to ≤4MgC/ha after selective harvesting of stands commences following maturation–but the timing of this rate change could not be reliably ascertained. The high standing carbon stocks and high annual accumulation rates point to the possibility of successful carbon farming using bamboo, if stands are managed efficiently (sufficient water, adequate nutrients, appropriate thinning/harvesting). Key in long-term carbon sequestration of bamboo is making sure harvested bamboo are turned into durable products (e.g., permanent construction materials, furniture, art). While our review demonstrated the potential of bamboo as an efficient and effective carbon sink, further research is needed to reduce uncertainties in the underlying data, resulting from a lack of standardization of methods, a lack of research for many bamboo species, and limited research of below-ground and soil organic carbon. Another priority is obtaining more carbon estimates for under-represented regions such as Central America, South America and Africa. Finally, we conducted a case study in northern Thailand that demonstrated the difficulty in sampling above- and below-ground components of total ecosystem carbon, as well as the threat of drastic bamboo biomass loss associated with instances of gregarious flowering. Overall, we recommend that instead of being seen as an invasive species with low utility, bamboo should be given greater recognition in policy and management for its value as a carbon sink, critical in mitigating the effects of climate change, and for its ability to provide key ecosystem services for humans, such as stabilizing hillslopes from accelerated soil erosion, improving soil fertility, and providing food and construction materials.
LaManna
(Reports, 30 June 2017, p. 1389) found higher conspecific negative density dependence in tree communities at lower latitudes, yielding a possible mechanistic explanation for the latitudinal ...diversity gradient. We show that their results are artifacts of a selective data transformation and a forced zero intercept in their fitted model. A corrected analysis shows no latitudinal trend.
Theoretical ecologists have analysed a range of neutral models but few including stage structure. Here we introduce a stage‐structured neutral model, by extending the standard spatial neutral model ...to have two‐stage classes: a juvenile stage and a reproductive stage. We find that formulas for biodiversity patterns (e.g. species–area relationships and species abundance distributions) of reproductives in the stage‐structured model can be obtained from the corresponding standard formulas via a parameter rescaling, which involves calculating an effective speciation rate parameter and an effective dispersal parameter. This is useful because it means existing knowledge about the non‐stage‐structured model can be transferred to the stage‐structured model, providing that applications focus exclusively on the reproductive stage. One surprising implication is that the presence of a juvenile stage can substantially increase the species richness of reproductive individuals: a juvenile stage with a length fraction k that of the reproductive stage increases reproductive species richness by roughly the same factor. We apply our new formulas to a case study of tropical forest trees in Panama and find that while the stage‐structured model makes different predictions than the standard model, it does not fix known problems with cross‐scale predictions. We speculate that some of our results, in particular the result that the presence of a juvenile stage increases community diversity, likely apply to non‐neutral systems as well.
The purpose of this study was to evaluate the accuracy of the Polar M600 optical heart rate (OHR) sensor compared with ECG heart rate (HR) measurement during various physical activities.
Thirty-six ...subjects participated in a continuous 76-min testing session, which included rest, cycling warm-up, cycling intervals, circuit weight training, treadmill intervals, and recovery. HR was measured using a three-lead ECG configuration and a Polar M600 Sport Watch on the left wrist. Statistical analyses included OHR percent accuracy, mean difference, mean absolute error, Bland-Altman plots, and a repeated-measures generalized estimating equation design. OHR percent accuracy was calculated as the percentage of occurrences where OHR measurement was within and including ±5 bpm from the ECG HR value.
Of the four exercise phases performed, the highest OHR percent accuracy was found during cycle intervals (91.8%), and the lowest OHR percent accuracy occurred during circuit weight training (34.5%). OHR percent accuracy improved steadily within exercise transitions during cycle intervals to a maximum of 98.5% and during treadmill intervals to a maximum of 89.0%. Lags in HR calculated by the Polar M600 OHR sensor existed in comparison to ECG HR, when exercise intensity changed until steady state occurred. There was a tendency for OHR underestimation during intensity increases and overestimation during intensity decreases. No statistically significant interaction effect with device was found in this sample on the basis of sex, body mass index, V˙O2max, skin type, or wrist size.
The Polar M600 was accurate during periods of steady-state cycling, walking, jogging, and running, but less accurate during some exercise intensity changes, which may be attributed to factors related to total peripheral resistance changes and pulse pressure.
•Biomass allometric equations for 12 land cover types in Southeast Asia were reviewed.•Equations for root biomass have high uncertainty due to sampling difficulties.•Inappropriate uses of equations ...identified and discussed in relation to uncertainty.•Few allometric equations exist for agroforest and rubber and oil palm plantations.•Further evaluation of current methods of collecting field data are needed.
Our review of biomass studies conducted for 11 Southeast Asian countries, Papua New Guinea, and southern China uncovered 402 above-ground and 138 below-ground biomass allometric equations for the following major land covers: forest, peat swamp forest, mangrove forest, logged over forest, orchard and tree plantation, rubber plantation, oil palm plantation, bamboo, swidden fallow, and grassland/pasture/shrub land. No equations existed for non-swidden agroforest and permanent croplands, two other important land covers involved in current and projected land-cover transitions. We also found 245 stem-volume equations and 50 height-diameter equations. Applying existing allometric equations out of convenience is potentially a key source of uncertainty in above- and below-ground carbon stock estimates in many SE Asian landscapes. Differences in environmental conditions and vegetation characteristics should preclude the use of many pre-existing equations at locations outside of the geographical location where they were developed, without first verifying their applicability. While use of site-specific equations is preferred to reduce uncertainty in estimates, there are few in existence for many land covers and many geographical areas of the region. For example, few or no equations exist for Brunei, Cambodia, Laos, Papua New Guinea, Singapore, and Timor Leste. Ten or fewer above-ground biomass equations exist for rubber plantation, oil palm plantation, non-swidden agroforest, grassland/pasture/shrublands, and permanent croplands for the entire region. Even site-specific equations can introduce uncertainties to biomass estimates if they were determined from an insufficient sample size. Difficulties associated with sampling below-ground root biomass accurately often leads to allometric equations that potentially under-estimate below-ground biomass. In addition, substantial errors may be present if these below-ground equations are conveniently used by researchers in lieu of site-specific measurements. Although the importance of including wood density in allometry is increasingly recognized, only 26 of the reviewed studies did so. Ideally, when wood density values are used to estimate biomass, new on-site measurements should be taken, rather than relying on pre-existing values. This review demonstrates that more research in SE Asia is needed on biomass in general, specifically for several land covers including peat swamp forest, rubber and oil palm plantations, bamboo, swidden fallow, non-swidden agroforest, and permanent cropland. Importantly, for the purpose of informing the development and implementation of policies and programs such as REDD+, our meta-analysis highlights the pressing need to address the insufficient number of allometric equations and the possible inappropriate use of some when estimating vegetation biomass related to current and potential land cover changes in the region.
A long‐standing puzzle in ecology is coexistence of many species despite relatively few limiting resources. Studies using competitive community models have found that temporal environmental ...stochasticity (TES) can provide a solution by providing a rare‐species advantage, for example by creating temporal niches. However, this appears to contradict studies using population models, which have found that TES‐induced temporal fluctuations in species abundances increase the chance of species becoming rare and hence increase their extinction risk. Here, we clarified how TES affects species richness by analysing a competitive community model using a novel mean‐field approach. We found that when temporal correlation in TES was weak, the dominant effect of TES was to create temporal niches by decreasing the strength of interspecific competition via a temporal averaging effect, thereby increasing species richness relative to the neutral case without TES. In contrast, when temporal correlation was strong, the dominant effect of TES was to increase the strength of selection and hence interspecific competition, thereby decreasing species richness. Compared with these indirect community effects of TES, the direct effects of TES on species richness via temporal fluctuations in abundances of species populations were relatively minor.
Many infectious diseases exist as multiple variants, with interactions between variants potentially driving epidemiological dynamics. These diseases include dengue, which infects hundreds of millions ...of people every year and exhibits complex multi-serotype dynamics. Antibodies produced in response to primary infection by one of the four dengue serotypes can produce a period of temporary cross-immunity (TCI) to infection by other serotypes. After this period, the remaining antibodies can facilitate the entry of heterologous serotypes into target cells, thus enhancing severity of secondary infection by a heterologous serotype. This represents antibody-dependent enhancement (ADE). In this study, we analyze an epidemiological model to provide novel insights into the importance of TCI and ADE in producing cyclic outbreaks of dengue serotypes. Our analyses reveal that without TCI, such cyclic outbreaks are synchronous across serotypes and only occur when ADE produces high transmission rates. In contrast, the presence of TCI allows asynchronous cycles of serotypes by inducing a time lag between recovery from primary infection by one serotype and secondary infection by another, with such cycles able to occur without ADE. Our results suggest that TCI is a fundamental driver of asynchronous cycles of dengue serotypes and possibly other multi-variant diseases.
Ligamentous Posttraumatic Ankle Osteoarthritis Valderrabano, Victor; Hintermann, Beat; Horisberger, Monika ...
The American journal of sports medicine,
04/2006, Volume:
34, Issue:
4
Journal Article
Peer reviewed
Background: Ankle sprains are the most common injuries in sports and recreational activities.
Hypothesis: Ankle osteoarthritis can be caused by ankle ligament lesions. Latency time between injury and ...osteoarthritis is influenced
by the type and side of the injured ligaments. The side of the ligamentous lesion correlates with the hindfoot alignment.
Study Design: Case series; Level of evidence, 4.
Methods: Of a cohort of 247 patients with ankle arthritis, we reviewed data from 30 patients (33 ankles; mean age, 58.6 years) with
ligamentous end-stage ankle osteoarthritis. The patients were evaluated etiologically, clinically, and radiologically.
Results: Etiologic analysis: 55% had a ligamentous lesion from sports injuries (soccer, 33%); 85% injured the lateral ankle ligaments,
and 15% injured the medial and medial-lateral ligaments. The mean latency time between injury and osteoarthritis was 34.3
years. The survivorship rate for single severe ankle sprains was worse than that for chronic recurrent ligamentous lesions
(mean latency time, 25.7 vs 38.0 years; P < .05), and the rate for medial sprains was worse than for lateral sprains (mean latency time, 27.5 vs 35.0 years; P < .05). At follow-up, the American Orthopaedic Foot and Ankle Society hindfoot score was 23.0 points, 52% had varus malalignment,
52% had persistent instability, and the mean ankle arthritis grade was 2.6 points. There was a correlation between chronic
lateral ankle instability and varus malalignment.
Conclusion: Lateral ankle sprains in sports are the main cause of ligamentous posttraumatic ankle osteoarthritis and correlate with varus
malalignment. At the time of end-stage ligamentous ankle osteoarthritis, persistent instability may be encountered.
Keywords:
ankle
arthritis
ligament
sports
trauma
Theoretical and empirical studies suggest that as immigration increases, ecological communities transition from a niche-structured regime to an immigration-structured regime. The niche-structured ...regime is the domain of classic niche models; the immigration-structured regime is the domain of island biogeography and related theories. A recent unified model predicted a biphasic species–area relationship (SAR) arising from the transition between the two regimes, but the generality and scope of this relationship remain unclear. Here we study the transition further to address three key questions: (1) Can MacArthur and Wilson’s classic graphical paradigm of intersecting immigration and extinction curves be adapted to capture the niche-structured regime that occurs at low-immigration rates? (2) Do different ecological models predict a similar biphasic SAR? (3) Can the biphasic island SAR be reconciled with the classic triphasic SAR observed in mainland biogeography? On the first point, we find that the transition can be incorporated into MacArthur and Wilson’s graphical paradigm by forcing the extinction curves sharply downwards at low species richness, reflecting the stabilizing effect of niche processes. On the second point, we confirm that a variety of simple ecological models produce qualitatively similar biphasic SARs. On the third point, we find that a unified model predicts an overall four-phase SAR with the second phase being a shallow niche-structured phase that is rarely observed in mainland SARs, which we hypothesize is because local communities on mainlands are usually in the immigration-structured regime.
The estimation of population allele frequencies using sample data forms a central component of studies in population genetics. These estimates can be used to test hypotheses on the evolutionary ...processes governing changes in genetic variation among populations. However, existing studies frequently do not account for sampling uncertainty in these estimates, thus compromising their utility. Incorporation of this uncertainty has been hindered by the lack of a method for constructing confidence intervals containing the population allele frequencies, for the general case of sampling from a finite diploid population of any size. In this study, we address this important knowledge gap by presenting a rigorous mathematical method to construct such confidence intervals. For a range of scenarios, the method is used to demonstrate that for a particular allele, in order to obtain accurate estimates within 0.05 of the population allele frequency with high probability (> or = 95%), a sample size of > 30 is often required. This analysis is augmented by an application of the method to empirical sample allele frequency data for two populations of the checkerspot butterfly (Melitaea cinxia L.), occupying meadows in Finland. For each population, the method is used to derive > or = 98.3% confidence intervals for the population frequencies of three alleles. These intervals are then used to construct two joint > or = 95% confidence regions, one for the set of three frequencies for each population. These regions are then used to derive a > or = 95%% confidence interval for Jost's D, a measure of genetic differentiation between the two populations. Overall, the results demonstrate the practical utility of the method with respect to informing sampling design and accounting for sampling uncertainty in studies of population genetics, important for scientific hypothesis-testing and also for risk-based natural resource management.
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