Nutrient additions affecting matter turnover in forest and pasture ecosystems

Nutrient inputs into ecosystems of the tropical mountain rainforest region are projected to further increase in the next decades. To investigate whether important ecosystem services such as nutrient cycling and matter turnover in native forests and pasture ecosystems show different patterns of response, two nutrient addition experiments have been established: NUMEX in the forest and FERPAST at the pasture. Both ecosystems already responded 1.5 years after the start of nutrient application (N, P, NP, Ca). Interestingly, most nutrients remained in the respective systems. While the pasture grass was co-limited by N and P, most tree species responded to P addition. Soil microbial biomass in the forest litter layer increased after NP fertilization pointing to nutrient co-limitation. In pasture soils, microorganisms were neither limited by N nor P. The results support the hypothesis that multiple and temporally variable nutrient limitations can coexist in tropical ecosystems.

Horizontal ridge augmentation in conjunction with or prior to implant placement in the anterior maxilla: a systematic review.

PURPOSE To systematically review clinical studies examining the survival and success rates of implants in horizontal ridge augmentation, either prior to or in conjunction with implant placement in the anterior maxilla. MATERIALS AND METHODS A literature search was undertaken up to September 2012 including clinical studies in English with ≥ 10 consecutively treated patients and a mean follow-up of at least 12 months. Two reviewers screened the pertinent articles and extracted the data. Key words focused on the outcome parameters (implant success, implant survival, horizontal bone gain, and intra- and postoperative complications) in studies utilizing either a simultaneous approach (ridge augmentation performed at the time of implant placement) or a staged approach (ridge augmentation performed prior to implant placement) were analyzed. RESULTS A total of 13 studies met the inclusion criteria, with 2 studies in the simultaneous group and 11 studies in the staged group. In the simultaneous group, survival rates of implants were 100% in both studies, with one study also reporting a 100% implant success rate. No data on horizontal bone gain were available. In the staged group, success rates of implants placed in horizontally augmented ridges ranged from 96.8% to 100% (two studies), and survival rates ranged from 93.5% to 100% (five studies). However, follow-up periods differed widely (up to 4.1 years). Mean horizontal bone gain determined at reentry (implant placement) ranged from 3.4 to 5.0 mm with large overall variations (0 to 9.8 mm, five studies). Intraoperative complications were not reported. Postsurgical complications included mainly mucosal dehiscences (five studies), and, occasionally, complete failures of block grafts were described in one study. CONCLUSIONS Staged and simultaneous augmentation procedures in the anterior maxilla are both associated with high implant success and survival rates. The level of evidence, however, is better for the staged approach than for the simultaneous one.

Horizontal head titubation in infants with Joubert syndrome: a new finding

AIM Head thrusts are well documented in Joubert syndrome and ocular motor apraxia. We provide a detailed clinical characterization of head titubation in 13 young children with Joubert syndrome. METHOD Detailed characterization of head titubation was assessed by targeted clinical evaluation and/or analysis of videos. RESULTS In 12 of 13 children (eight males, five females; median age 6y, range 2mo-15y) head titubation was first recognized in the first 2 months of age and decreased in severity until spontaneous resolution. In all children, the head titubation was horizontal, high frequency (~3Hz), had small amplitude (5-10°), was never present during sleep, and did not interfere with the neurodevelopment during infancy. In the majority of children, emotion, anxiety, and tiredness were worsening factors for head titubation. INTERPRETATION Head titubation is a benign, early presentation of Joubert syndrome. Head titubation in hypotonic infants should prompt a careful search for Joubert syndrome. Awareness of its occurrence in Joubert syndrome may avoid unnecessary investigations.

Reading performance is not affected by a prism induced increase of horizontal and vertical vergence demand

PURPOSE Dyslexia is the most common developmental reading disorder that affects language skills. Latent strabismus (heterophoria) has been suspected to be causally involved. Even though phoria correction in dyslexic children is commonly applied, the evidence in support of a benefit is poor. In order to provide experimental evidence on this issue, we simulated phoria in healthy readers by modifying the vergence tone required to maintain binocular alignment. METHODS Vergence tone was altered with prisms that were placed in front of one eye in 16 healthy subjects to induce exophoria, esophoria, or vertical phoria. Subjects were to read one paragraph for each condition, from which reading speed was determined. Text comprehension was tested with a forced multiple choice test. Eye movements were recorded during reading and subsequently analyzed for saccadic amplitudes, saccades per 10 letters, percentage of regressive (backward) saccades, average fixation duration, first fixation duration on a word, and gaze duration. RESULTS Acute change of horizontal and vertical vergence tone does neither significantly affect reading performance nor reading associated eye movements. CONCLUSION Prisms in healthy subjects fail to induce a significant change of reading performance. This finding is not compatible with a role of phoria in dyslexia. Our results contrast the proposal for correcting small angle heterophorias in dyslexic children.

Enhanced-depth optical coherence tomography for imaging horizontal rectus muscles in Graves' orbitopathy.

PURPOSE Graves' orbitopathy (GO) is an extraocular eye disease with symptoms ranging from minor discomfort from dry eyes to strabismus and visual loss. One of the hallmarks of active GO is visible hyperemia at the insertion of the extraocular muscles. The aim of the present study was to evaluate the use of enhanced-depth imaging spectral domain anterior segment optical coherence tomography (EDI SD AS-OCT) for detecting pathological changes in horizontal recti muscles of patients with GO. METHODS Prospective cross sectional study of 27 eyes. Only women were included. EDI AS-OCT was used to measure the thickness of the tendons of the horizontal recti muscles in a predefined area in patients with GO and healthy controls. RESULTS EDI AS-OCT was able to image the tendons of the horizontal recti muscles in both healthy controls and patients suffering from GO. The mean thickness of the medial rectus muscle (MR) tendon was 256.4 μm [±17.13 μm standard deviation (SD)] in the GO group and, therefore, significantly thicker (p = 0.046) than in the healthy group which had a mean thickness of 214.7 μm (±5.516 μm SD). There was no significant difference in the mean thickness of the tendon of the lateral recti muscles (LRs) between these groups. CONCLUSION This is the first report showing that EDI AS-OCT is suitable to detect swelling at the insertion site of the MR muscle in GO. MR tendon thickness may be a useful parameter to monitor activity in these patients.

Sustainable Pasture Management : LforS learning and simulation game

Three teams consisting of 2 to 5 persons each play the game. Each team represents a farm. Each team decides jointly on its strategy. In annual meetings in winter, the farm teams jointly discuss, evaluate and decide on how to proceed and actions to be taken. The farms make use of three different pasture areas (village pasture, intensive pasture and summer pasture) for grazing their livestock. The carrying capacity of each pasture area is different and varies according to the season. In each season, the farms have to decide on how many livestock units to graze on which pasture. Overgrazing and pasture degradation occur if the total number of livestock units exceeds the carrying capacity of a specific pasture area. Overgrazing results in a reduction of pasture productivity. To diversify and improve their livelihood strategy farms can make individual investments to increase productivity at the farm level, eg. in fodder production or in income generating activities. At the community level, collective investments can be made which may influence livestock and household economy, e.g. rehabilitate and improve pasture productivity, improve living conditions on remote pastures etc. Events occurring in the course of the game represent different types of (risk) factors such as meteorology, market, politics etc. that may positively or negatively influence livestock production and household economy. A sustainable management of pastures requires that farms actively regulate the development of their herds, that they take measures to prevent pasture degradation and to improve pasture productivity, and that they find a balance between livestock economy and other productive activities. The game has a double aim: a) each farm aims at its economic success and prosperity, and b) the three farm teams jointly have to find and implement strategies for a sustainable use of pasture areas.

Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.

Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro

In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866–4550m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies.

Sharp comparison and maximum principles via horizontal normal mapping in the Heisenberg group

In this paper we solve a problem raised by Gutiérrez and Montanari about comparison principles for H−convex functions on subdomains of Heisenberg groups. Our approach is based on the notion of the sub-Riemannian horizontal normal mapping and uses degree theory for set-valued maps. The statement of the comparison principle combined with a Harnack inequality is applied to prove the Aleksandrov-type maximum principle, describing the correct boundary behavior of continuous H−convex functions vanishing at the boundary of horizontally bounded subdomains of Heisenberg groups. This result answers a question by Garofalo and Tournier. The sharpness of our results are illustrated by examples.

Beyond a logic of effectiveness: Horizontal coordination, democratic legitimacy and accountability

Horizontal coordination, where actors join together to accomplish a common task, has been applauded for its output legitimacy. However, such processes often face challenges due to opposition from local actors who raise concerns about democratic legitimacy and accountability. Moving beyond a logic of effectiveness, we aim to show how and why other forms of legitimacy such as input and throughput dimensions also affect horizontal coordination, in addition to output criteria. Beyond the assumed positive relationship between coordination and effectiveness, we additionally expect horizontal coordination to be (a) impeded by local actors' fear of losing democratic legitimacy; and (b) fostered by accountability in terms of the steering capacity of the state. A comparative case study analysis of water supply structures at the regional level in Switzerland shows, in contrast to our expectation, that effectiveness has mixed impacts on horizontal coordination. Rather than being solely a positive factor for horizontal coordination, certain output criteria such as financial redistribution are found to be a key hindrance. We also find that democratic legitimacy may, indeed, impede horizontal coordination whereas increased accountability positively affects such coordination.

Enriching plant diversity in grasslands by large-scale experimental sward disturbance and seed addition along gradients of land-use intensity

Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research. Furthermore, enhancing the diversity of degraded ecosystems is a major goal in applied restoration ecology. In grasslands, many species may be locally absent due to dispersal or microsite limitation and may therefore profit from mechanical disturbance of the resident vegetation. We established a seed addition and disturbance experiment across several grassland sites of different land use to test whether plant diversity can be increased in these grasslands. Additionally, the experiment will allow us testing the consequences of increased plant diversity for ecosystem processes and for the diversity of other taxa in real-world ecosystems. Here we present details of the experimental design and report results from the first vegetation survey one year after disturbance and seed addition. Moreover, we tested whether the effects of seed addition and disturbance varied among grassland depending on their land use or pre-disturbance plant diversity. Methods A full-factorial experiment was installed in 73 grasslands in three regions across Germany. Grasslands were under regular agricultural use, but varied in the type and the intensity of management, thereby representing the range of management typical for large parts of Central Europe. The disturbance treatment consisted of disturbing the top 10 cm of the sward using a rotavator or rotary harrow. Seed addition consisted of sowing a high-diversity seed mixture of regional plant species. These species were all regionally present, but often locally absent, depending on the resident vegetation composition and richness of each grassland. Important findings One year after sward disturbance it had significantly increased cover of bare soil, seedling species richness and numbers of seedlings. Seed addition had increased plant species richness, but only in combination with sward disturbance. The increase in species richness, when both seed addition and disturbance was applied, was higher at high land-use intensity and low resident diversity. Thus, we show that at least the early recruitment of many species is possible also at high land-use intensity, indicating the potential to restore and enhance biodiversity of species-poor agricultural grasslands. Our newly established experiment provides a unique platform for broad-scale research on the land-use dependence of future trajectories of vegetation diversity and composition and their effects on ecosystem functioning.