Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest ...carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.
To assess the safety, tolerability, and biological activity of glial cell line-derived neurotrophic factor (GDNF) administered by an implanted intracerebroventricular (ICV) catheter and access port ...in advanced PD.
GDNF is a peptide that promotes survival of dopamine neurons. It improved 6-OHDA- or MPTP-induced behavioral deficits in rodents and monkeys.
A multicenter, randomized, double-blind, placebo-controlled, sequential cohort study compared the effects of monthly ICV administration of placebo and 25, 75, 150, 300, and 500 to 4,000 microg of GDNF in 50 subjects with PD for 8 months. An open-label study extended exposure up to an additional 20 months and maximum single doses of up to 4,000 microg in 16 subjects. Laboratory testing, adverse events (AE), and Unified Parkinson's Disease Rating Scale (UPDRS) scoring were obtained at 1- to 4-week intervals throughout the studies.
Twelve subjects received placebo and seven or eight subjects were assigned to each of the other GDNF dose groups. "On" and "off" total and motor UPDRS scores were not improved by GDNF at any dose. Nausea, anorexia, and vomiting were common hours to several days after injections of GDNF. Weight loss occurred in the majority of subjects receiving 75 microg or larger doses of GDNF. Paresthesias, often described as electric shocks (Lhermitte sign), were common in GDNF-treated subjects, were not dose related, and resolved on discontinuation of GDNF. Asymptomatic hyponatremia occurred in over half of subjects receiving 75 microg or larger doses of GDNF; it was symptomatic in several subjects. The open-label extension study had similar AE and lack of therapeutic efficacy.
GDNF administered by ICV injection is biologically active as evidenced by the spectrum of AE encountered in this study. GDNF did not improve parkinsonism, possibly because GDNF did not reach the target tissues--putamen and substantia nigra.
The neuropeptide calcitonin gene-related peptide (CGRP) plays a key role in migraine pathophysiology. In this large phase 3 clinical trial, we sought to confirm the efficacy of telcagepant, the first ...orally bioavailable CGRP receptor antagonist.
Adults with migraine with or without aura (International Headache Society criteria) treated a moderate or severe attack with oral telcagepant 50 mg (n = 177), 150 mg (n = 381), 300 mg (n = 371), or placebo (n = 365) in a randomized, double-blind trial. The 5 co-primary endpoints were pain freedom, pain relief, and absence of photophobia, absence of phonophobia, and absence of nausea, all at 2 hours postdose. The key secondary endpoint was 2-24 hour sustained pain freedom. The prespecified primary efficacy analyses evaluated the 150 mg and 300 mg groups; the 50-mg group was included on an exploratory basis to further characterize the dose response but was not prespecified for analysis. Tolerability was assessed by adverse experience reports.
Telcagepant 300 mg was more effective (p <or= 0.001) than placebo on all primary endpoints and the key secondary endpoint, as was telcagepant 150 mg (p <or= 0.05). Telcagepant 300 mg showed a slight numeric advantage over telcagepant 150 mg on most measures. Telcagepant 50 mg values were numerically intermediate between placebo and telcagepant 150 mg and 300 mg. The percentages of patients with adverse experiences were 32.2% for telcagepant 50 mg, 32.0% for telcagepant 150 mg, 36.2% for telcagepant 300 mg, and 32.2% for placebo.
This study confirmed previous findings that telcagepant 300 mg was effective at relieving pain and other migraine symptoms at 2 hours and providing sustained pain freedom up to 24 hours. In this study, telcagepant 150 mg was also effective. Telcagepant was generally well tolerated.
The juvenile life stage is a crucial determinant of forest dynamics and a first indicator of changes to species' ranges under climate change. However, paucity of detailed re‐measurement data of ...seedlings, saplings and small trees means that their demography is not well understood at large scales, and rarely represented in forest models in detail. In this study we quantify the effects of climate and density dependence on recruitment and juvenile growth and mortality rates of thirteen species measured in the Spanish Forest Inventory. Single‐census sapling count data is used to constrain demographic parameters of a simple forest juvenile dynamics model based on the perfect plasticity approximation model (PPA) within a likelihood‐free parameterisation method, Approximate Bayesian Computation. Our results highlight marked differences between species, and the important role of climate and stand structure, in controlling juvenile dynamics. Recruitment had a hump‐shaped relationship with conspecific density, and for most species conspecific competition had a stronger negative effect than heterospecific competition. Mediterranean species showed on average higher mortality and lower growth rates than temperate species, and in low density stands recruitment and mortality rates were positively correlated. Under climate change our model predicted declines in recruitment rates for almost all species. Reliable predictive models of forest dynamics should include realistic representation of critical early life‐stage processes and our approach demonstrates that existing coarse count data can be used to parameterise such models. Approximate Bayesian Computation may have wide application in many fields of ecology to unlock information about past processes from single survey observations.
Communities across trophic levels, and the functional roles they play, are vital for the sustained provision of ecosystem services. In forest systems, diversification of overstorey composition has ...been shown to be a key driver of biodiversity, but its influence on across‐trophic level relationships remains scarcely known. Species across trophic levels in varied overstorey compositions are also differentially susceptible to fragmentation context. We hypothesise that fragmentation will disrupt community relationships associated with particular overstorey compositions.
We test this hypothesis using a tree diversity research platform across 53 deciduous woodland plots in central Belgium. We estimate species’ abundances within nine, generally taxonomic, community groups across trophic levels: understorey vegetation; leaf miners and gall formers; woodlice, millipedes; carabid beetles, harvestmen, spiders, birds, bats. We use multiple co‐inertia analyses to examine how taxonomic and trophic role community matrices covary across gradients of overstorey composition, via three different tree species diversification pathways, and fragmentation.
For all trophic role groups, across all plots, there was at least one significant pairwise comparison. Apart from comparisons involving bats, there was at least one significant pairwise correlation between taxonomic groups too. These results indicate correlated community matrices across trophic levels. Overstorey composition related to community tightness, that is, the level of co‐ordinated change among taxonomic and/or trophic role groups as revealed by multiple co‐inertia analyses. Notably, diversifying woodlands of beech Fagus sylvatica or red oak Quercus rubra with pedunculate oak Quercus robur correlated with increased taxonomic community tightness. Diversifying pedunculate oak forest stands with other overstorey species related to unchanged community tightness. Evidence was lacking for fragmentation affecting community tightness, singly or by interacting with overstorey composition.
Synthesis. Overall, changing tree species composition and fragmentation level affected across‐trophic level community relationships differently. Yet, we demonstrated a clear signal that diversifying monoculture stands with particular species correlated with greater community tightness, and co‐ordinated change among sets of community groups, across trophic levels and regardless of fragmentation context. We postulate that having tighter community relationships suggests that measures to improve biodiversity at one trophic level (i.e. trees) could affect other groups, and their associated roles, in a co‐ordinated manner.
Gemeenschappen op verschillende trofische niveaus vervullen functionele rollen die van vitaal belang zijn voor het leveren van duurzame ecosysteemdiensten. Eerder bleek reeds dat een gemengde boomsoortensamenstelling de biodiversiteit in bossen bevoordeelt, maar effecten op de onderlinge relaties tussen de verschillende trofische niveaus zijn minder goed gekend. Bovendien blijken soorten op verschillende trofische niveaus ook een andere gevoeligheid voor versnippering van bossen te vertonen. We voorspellen dan ook dat zulke versnippering de relaties tussen de gemeenschappen in bossen met welbepaalde boomsoorten zal verstoren.
We testen deze hypothese met behulp van een onderzoeksplatform voor de studie van boomsoortendiversiteit, in 53 plots in loofbossen gelegen in centraal België. We schatten de abundanties van de soorten binnen negen (overwegend taxonomische) entiteiten die deel uitmaken van gemeenschappen op verschillende trofische niveaus: kruidlaagvegetatie; bladmineerders en galvormers; pissebedden, duizendpoten; loopkevers, hooiwagens, spinnen, vogels, vleermuizen. We gebruiken verschillende co‐inertia analyses om te onderzoeken hoe de samenstelling van de gemeenschappen (ingedeeld naar taxonomische of trofische groep) co‐varieert langsheen gradiënten in boomsoortensamenstelling en versnippering van de bossen.
Overheen alle plots werd minstens één significante paarsgewijze correlatie gevonden tussen de verschillende trofische groepen. Behalve voor vleermuizen, werd ook minstens één significante paarsgewijze correlatie gevonden tussen de verschillende taxonomische groepen. Dit wijst op gecorreleerde gemeenschapsmatrices over trofische niveaus heen. Uit onze co‐inertia analyses bleek verder dat de boomsoortensamenstelling gerelateerd was aan de mate van ‘community tightness’, een index voor de sterkte van gerelateerde veranderingen tussen taxonomische en/of trofische groepen. Waar een bijmenging met zomereik (Quercus robur) in opstanden van beuk (Fagus sylvatica) en Amerikaanse eik (Quercus rubra) gerelateerd bleek aan een verhoging in community tightness, bleek dit niet het geval wanneer er in opstanden van zomereik andere soorten werden bijgemengd. Er werden ook geen aanwijzingen gevonden voor effecten van de vernippering van de bossen op tightness, zowel op zichzelf als in interactie met de boomsoortensamenstelling.
Synthese. De relaties tussen gemeenschappen die zich op verschillende trofische niveaus bevinden, werden op een verschillende manier beïnvloed door veranderingen in de boomsoortensamenstelling en in de mate van versnippering van de bossen. Toch vonden we een duidelijk signaal dat het bijmengen van boomsoorten in monoculturen leidt tot een sterkere mate van community tightness en parallelle veranderingen in de samenstelling van de verschillende gemeenschappen, en dit overheen de trofische niveaus en ongeacht de mate van versnippering. Uit deze verhoogde community tightness besluiten we dat maatregelen die gericht zijn op het verhogen van de biodiversiteit op één trofisch niveau (bv. bomen) kan leiden tot veranderingen op andere trofische niveaus, alsook in de ecosysteemrol die ze vervullen.
Here, we demonstrate a clear signal that diversifying monoculture stands with particular species correlated with co‐ordinated change among sets of community groups (i.e. greater ‘community tightness’) regardless of fragmentation context. We postulate that tighter community relationships mean biodiversity improvements at one trophic level (i.e. trees) could affect other groups, and their associated functional roles, in a co‐ordinated manner.
Ash Dieback (ADB) has been present in the UK since 2012 and is expected to kill up to 80% of UK ash trees. Detecting and quantifying the extent of ADB in individual tree crowns (ITCs), which is ...crucial to understanding resilience and resistance, currently relies on visual assessments which are impractical over large scales or at high frequency. The improved imaging capabilities and declining cost of consumer UAVs, together with new remote sensing methods such as structure from motion photogrammetry (SfM) offers potential to quantify the fine‐scale structural and spectral metrics of ITCs that are indicative of ADB, rapidly, and at low‐cost.
We extract high‐resolution 3D RGB point clouds derived from SfM of canopy ash trees taken monthly throughout the growing season at Marden Park, Surrey, UK, a woodland impacted by ADB. We segment ITCs, extract green chromatic coordinate (gcc), and test the relationship with visual assessments of crown health. Next, we quantify spatial patterning of dieback within ITCs by testing the relationship between internal variation of gcc and path length, a measure of the distance from foliage to trunk, for small clusters of foliage.
We find gcc correlates with visual assessments of crown health throughout the growing season, but the strongest relationships are in measurements taken after peak greenness, when the effects of ADB on foliage are likely to be most prevalent. We also find a negative relationship between gcc and path length in infected trees, indicating foliage loss is more severe at crown extremities.
We demonstrate a new method for identifying ADB at scale using a consumer‐grade 3D RGB UAV system and suggest this approach could be adopted for widespread rapid monitoring. We recommend the optimum time of year for data acquisition, which we find to be an important factor for detecting ADB. Although here applied to ADB, this framework is applicable to a multitude of drivers of crown dieback, presenting a method for identifying spectral‐structural relationships which may be characteristic of disturbance type.
Ash Dieback (ADB) has been present in the UK since 2012 and is expected to kill up to 80% of UK ash trees. Using high‐resolution 3D UAV data, we show correlation with visual assessments of crown health. In infected trees, we find characteristic spatial patterning of leaves, with dieback most evident at the extremities of crowns.
This study examined the effect of age on placebo response rates in rizatriptan trials in adults. Data from eight rizatriptan adult trials involving patients treating moderate/severe migraine attacks ...with rizatriptan 5 mg (N = 1819), rizatriptan 10 mg (N = 2046) or placebo (N = 1322) were pooled for post hoc analysis. Logistic regression was used to model 2-h pain relief (reduction to mild or none) and 2-h pain freedom rates by treatment groups. Older patients had lower placebo response rates than younger patients; the estimated odds ratio (older vs. younger) for a 10-year age increase was 0.83 for pain relief 95% confidence interval (CI) 0.75, 0.93 and 0.81 for pain freedom (95% CI 0.68, 0.97). The response proportion vs. age trend was flat for rizatriptan 5 mg and slightly increased for rizatriptan 10 mg. The treatment-by-age interaction was significant for pain relief (P < 0.001) and pain freedom (P = 0.001), suggesting an increasing trend of treatment advantage of rizatriptan over placebo as age increased. Age appeared to be an important predictor of placebo response rate in rizatriptan trials, with older patients being less likely to respond to placebo and more likely to respond to rizatriptan.
Accurate measurement of vegetation density metrics including plant, wood and leaf area indices (PAI, WAI and LAI) is key to monitoring and modelling carbon storage and uptake in forests. Traditional ...passive sensor approaches, such as digital hemispherical photography (DHP), cannot separate leaf and wood material, nor individual trees, and require many assumptions in processing. Terrestrial laser scanning (TLS) data offer new opportunities to improve understanding of tree and canopy structure. Multiple methods have been developed to derive PAI and LAI from TLS data, but there is little consensus on the best approach, nor are methods benchmarked as standard.
Papaya ringspot virus (PRSV), which has recently been identified inAustralia, is the major limiting factor in papaya production worldwide. In thispaper we report the development of two Australian ...papaya cultivars that areimmune to infection with PRSV. Papaya somatic embryos were transformed viamicroprojectile bombardment using a construct containing an untranslatable PRSVcoat protein coding region. Immunity was demonstrated by repeated inoculationinthe glasshouse and eighteen months in the field. The immune lines were shown tohave up to five copies of the transgene by Southern hybridisation. Northernhybridisation showed that the coat protein transcript in the immune linesappeared to be degraded; therefore, the mechanism of resistance appears to bepost transcriptional gene silencing via RNA degradation. We have taken aproactive approach to control of PRSV in Australia by developing geneticallyengineered resistance before the Australian papaya industry has been decimatedby the inevitable spread of PRSV.
The potyviruses Papaya ringspot virus (PRSV) is found throughout the tropics and subtropics. Its P biotype is a devastating pathogen of papaya crops and its W biotype of cucurbits. PRSV-P is thought ...to arise by mutation from PRSV-W. However, the relative impact of mutation and movement on the structure of PRSV populations is not well characterized. To investigate this, we have determined the coat protein sequences of isolates of both biotypes of PRSV from Vietnam (50), Thailand (13), India (1) and the Philippines (1), and analysed them together with 28 PRSV sequences already published, so that we can better understand the molecular epidemiology and evolution of PRSV. In Thailand, variation was greater among PRSV-W isolates (mean nucleotide divergence 7-6%) than PRSV-P isolates (mean 2-6%), but in Vietnamese populations the P and W biotypes were more but similarly diverse. Phylogenetic analyses of PRSV also involving its closest known relative, Moroccan watermelon mosaic virus, indicate that PRSV may have originated in Asia, particularly in the Indian subcontinent, as PRSV populations there are most diverse and hence have probably been present longest. Our analyses show that mutation, together with local and long-distance movement, contributes to population variation, and also confirms an earlier conclusion that populations of the PRSV-P biotype have evolved on several occasions from PRSV-W populations.
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