Functional and phylogenetic relationships link predators to plant diversity via trophic and non-trophic pathways.

Human-induced biodiversity loss negatively affects ecosystem function, but the interactive effects of biodiversity change across trophic levels remain insufficiently understood. We sampled arboreal spiders and lepidopteran larvae across seasons in 2 years in a subtropical tree diversity experiment, and then disentangled the links between tree diversity and arthropod predator diversity by deconstructing the pathways among multiple components of diversity (taxonomic, phylogenetic and functional) with structural equation models. We found that herbivores were major mediators of plant species richness effects on abundance, species richness, functional and phylogenetic diversity of predators, while phylogenetic, functional and structural diversity of trees were also important mediators of this process. However, the strength and direction differed between functional, structural and phylogenetic diversity effects, indicating different underlying mechanisms for predator community assembly. Abundance and multiple diversity components of predators were consistently affected by tree functional diversity, indicating that the variation in structure and environment caused by plant functional composition might play key roles in predator community assembly. Our study highlights the importance of an integrated approach based on multiple biodiversity components in understanding the consequences of biodiversity loss in multitrophic communities.

Cytosolic, but not matrix, calcium is essential for adjustment of mitochondrial pyruvate supply.

Mitochondrial oxidative phosphorylation (OXPHOS) and cellular workload are tightly balanced by the key cellular regulator, calcium (Ca2+). Current models assume that cytosolic Ca2+ regulates workload and that mitochondrial Ca2+ uptake precedes activation of matrix dehydrogenases, thereby matching OXPHOS substrate supply to ATP demand. Surprisingly, knockout (KO) of the mitochondrial Ca2+ uniporter (MCU) in mice results in only minimal phenotypic changes and does not alter OXPHOS. This implies that adaptive activation of mitochondrial dehydrogenases by intramitochondrial Ca2+ cannot be the exclusive mechanism for OXPHOS control. We hypothesized that cytosolic Ca2+, but not mitochondrial matrix Ca2+, may adapt OXPHOS to workload by adjusting the rate of pyruvate supply from the cytosol to the mitochondria. Here, we studied the role of malate-aspartate shuttle (MAS)-dependent substrate supply in OXPHOS responses to changing Ca2+ concentrations in isolated brain and heart mitochondria, synaptosomes, fibroblasts, and thymocytes from WT and MCU KO mice and the isolated working rat heart. Our results indicate that extramitochondrial Ca2+ controls up to 85% of maximal pyruvate-driven OXPHOS rates, mediated by the activity of the complete MAS, and that intramitochondrial Ca2+ accounts for the remaining 15%. Of note, the complete MAS, as applied here, included besides its classical NADH oxidation reaction the generation of cytosolic pyruvate. Part of this largely neglected mechanism has previously been described as the "mitochondrial gas pedal." Its implementation into OXPHOS control models integrates seemingly contradictory results and warrants a critical reappraisal of metabolic control mechanisms in health and disease.

Automatic extraction and measurement of individual trees from mobile laser scanning point clouds of forests.

BACKGROUND AND AIMS: In addition to terrestrial laser scanning (TLS), mobile laser scanning (MLS) is increasingly arousing interest as a technique which provides valuable 3-D data for various applications in forest research. Using mobile platforms, the 3-D recording of large forest areas is carried out within a short space of time. Vegetation structure is described by millions of 3-D points which show an accuracy in the millimetre range and offer a powerful basis for automated vegetation modelling. The successful extraction of single trees from the point cloud is essential for further evaluations and modelling at the individual-tree level, such as volume determination, quantitative structure modelling or local neighbourhood analyses. However, high-precision automated tree segmentation is challenging, and has so far mostly been performed using elaborate interactive segmentation methods. METHODS: Here, we present a novel segmentation algorithm to automatically segment trees in MLS point clouds, applying distance adaptivity as a function of trajectory. In addition, tree parameters are determined simultaneously. In our validation study, we used a total of 825 trees from ten sample plots to compare the data of trees segmented from MLS data with manual inventory parameters and parameters derived from semi-automatic TLS segmentation. KEY RESULTS: The tree detection rate reached 96 % on average for trees with distances up to 45 m from the trajectory. Trees were almost completely segmented up to a distance of about 30 m from the MLS trajectory. The accuracy of tree parameters was similar for MLS-segmented and TLS-segmented trees. CONCLUSIONS: Besides plot characteristics, the detection rate of trees in MLS data strongly depends on the distance to the travelled track. The algorithm presented here facilitates the acquisition of important tree parameters from MLS data, as an area-wide automated derivation can be accomplished in a very short time.

Neighbourhood-mediated shifts in tree biomass allocation drive overyielding in tropical species mixtures.

Variations in crown forms promote canopy space-use and productivity in mixed-species forests. However, we have a limited understanding on how this response is mediated by changes in within-tree biomass allocation. Here, we explored the role of changes in tree allometry, biomass allocation and architecture in shaping diversity-productivity relationships (DPRs) in the oldest tropical tree diversity experiment. We conducted whole-tree destructive biomass measurements and terrestrial laser scanning. Spatially explicit models were built at the tree level to investigate the effects of tree size and local neighbourhood conditions. Results were then upscaled to the stand level, and mixture effects were explored using a bootstrapping procedure. Biomass allocation and architecture substantially changed in mixtures, which resulted from both tree-size effects and neighbourhood-mediated plasticity. Shifts in biomass allocation among branch orders explained substantial shares of the observed overyielding. By contrast, root-to-shoot ratios, as well as the allometric relationships between tree basal area and aboveground biomass, were little affected by the local neighbourhood. Our results suggest that generic allometric equations can be used to estimate forest aboveground biomass overyielding from diameter inventory data. Overall, we demonstrate that shifts in tree biomass allocation are mediated by the local neighbourhood and promote DPRs in tropical forests.

Neighbour species richness and local structural variability modulate aboveground allocation patterns and crown morphology of individual trees.

Local neighbourhood interactions are considered a main driver for biodiversity-productivity relationships in forests. Yet, the structural responses of individual trees in species mixtures and their relation to crown complementarity remain poorly understood. Using a large-scale forest experiment, we studied the impact of local tree species richness and structural variability on above-ground wood volume allocation patterns and crown morphology. We applied terrestrial laser scanning to capture the three-dimensional structure of trees and their temporal dynamics. We found that crown complementarity and crown plasticity increased with species richness. Trees growing in species-rich neighbourhoods showed enhanced aboveground wood volume both in trunks and branches. Over time, neighbourhood diversity induced shifts in wood volume allocation in favour of branches, in particular for morphologically flexible species. Our results demonstrate that diversity-mediated shifts in allocation pattern and crown morphology are a fundamental mechanism for crown complementarity and may be an important driver of overyielding.

From competition to facilitation: how tree species respond to neighbourhood diversity.

Studies on tree communities have demonstrated that species diversity can enhance forest productivity, but the driving mechanisms at the local neighbourhood level remain poorly understood. Here, we use data from a large-scale biodiversity experiment with 24 subtropical tree species to show that neighbourhood tree species richness generally promotes individual tree productivity. We found that the underlying mechanisms depend on a focal tree's functional traits: For species with a conservative resource-use strategy diversity effects were brought about by facilitation, and for species with acquisitive traits by competitive reduction. Moreover, positive diversity effects were strongest under low competition intensity (quantified as the total basal area of neighbours) for acquisitive species, and under high competition intensity for conservative species. Our findings demonstrate that net biodiversity effects in tree communities can vary over small spatial scales, emphasising the need to consider variation in local neighbourhood interactions to better understand effects at the community level.

Tumour cell derived effects on monocyte/macrophage polarization and function and modulatory potential of Viscum album lipophilic extract in vitro.

BACKGROUND: Macrophages are highly versatile cells that play an important role in tumour microenvironment. Tumour associated macrophages (TAMs) have been linked to both, good or bad prognosis of several cancer types depending on their number, composition and polarization. Viscum album lipophilic extract (VALE) contains several pentacyclic triterpenes known to modulate the activity of monocytes and other immune cells and to exhibit anticancer properties. In our in vitro study, we investigated the effect of tumour cell lines on macrophage polarization and monocyte chemotactic transmigration and examined the modulatory potential of VALE and its predominant triterpene oleanolic acid (OA). METHODS: Human peripheral blood monocytes were differentiated into monocyte derived macrophages (MDM) using M-CSF and polarized into M1 by IFN-γ and LPS and into M2 macrophages by IL-4 and IL-13 or by co-culture with two different tumour cell lines. Polarized macrophages were subsequently treated with VALE or OA. Phenotypic markers and cytokines were assessed by flow cytometry and immunoanalysis. Migration of human peripheral blood monocytes induced by monocyte chemotactic protein-1 (MCP-1) or supernatants of different tumour cell lines under the influence of VALE or OA was measured in a chemotaxis transmigration assay. RESULTS: In vitro polarized M1 and M2 type macrophages revealed specific phenotypic patterns and tumour cell co-cultured MDM displayed ambiguous phenotypes with M1 as well as M2 associated markers. VALE and OA showed modest influence on cell surface marker profile and cytokine expression of tumour cell co-cultured macrophages. All tumour cell supernatants markedly enhanced the migratory activity of monocytes. VALE and OA significantly inhibited MCP-1 induced monocyte transmigration, whereas monocyte migration initiated by tumour cell derived supernatants was not affected. CONCLUSIONS: In our study we reconfirmed that co-culture with different tumour cell lines can result in a mixed macrophage phenotype with M1 as well as M2 patterns, a finding that is important for a better understanding of tumour microenvironment functions. Moreover, we demonstrated that VALE shows slight immunomodulatory effects on tumour cell co-cultured macrophages and modulates monocyte chemotactic transmigration in vitro, indicating promising possibilities of triterpenes from Viscum album L. to contribute in a multimodal concept of anti-cancer therapy in future. Our data contribute to an understanding of monocyte function and macrophage polarization in vitro and of the possibility to influence their behaviour by triterpene containing mistletoe extracts.

Interaction of standardized mistletoe (Viscum album) extracts with chemotherapeutic drugs regarding cytostatic and cytotoxic effects in vitro.

BACKGROUND: Given the importance of complementary and alternative medicine (CAM) to cancer patients, there is an increasing need to learn more about possible interactions between CAM and anticancer drugs. Mistletoe (Viscum album L.) belongs to the medicinal herbs that are used as supportive care during chemotherapy. In the in vitro study presented here the effect of standardized mistletoe preparations on the cytostatic and cytotoxic activity of several common conventional chemotherapeutic drugs was investigated using different cancer cell lines. METHODS: Human breast carcinoma cell lines HCC1937 and HCC1143 were treated with doxorubicin hydrochloride, pancreas adenocarcinoma cell line PA-TU-8902 with gemcitabine hydrochloride, prostate carcinoma cell line DU145 with docetaxel and mitoxantrone hydrochloride and lung carcinoma cell line NCI-H460 was treated with docetaxel and cisplatin. Each dose of the respective chemotherapeutic drug was combined with Viscum album extract (VAE) in clinically relevant concentrations and proliferation and apoptosis were measured. RESULTS: VAE did not inhibit chemotherapy induced cytostasis and cytotoxicity in any of our experimental settings. At higher concentrations VAE showed an additive inhibitory effect. CONCLUSIONS: Our in vitro results suggest that no risk of safety by herb drug interactions has to be expected from the exposition of cancer cells to chemotherapeutic drugs and VAE simultaneously.

CardioGenesis4D: Interactive Morphological Transitions of Embryonic Heart Development in a Virtual Learning Environment.

In the embryonic human heart, complex dynamic shape changes take place in a short period of time on a microscopic scale, making this development difficult to visualize. However, spatial understanding of these processes is essential for students and future cardiologists to properly diagnose and treat congenital heart defects. Following a user centered approach, the most crucial embryological stages were identified and translated into a virtual reality learning environment (VRLE) to enable the understanding of the morphological transitions of these stages through advanced interactions. To address individual learning types, we implemented different features and evaluated the application regarding usability, perceived task load, and sense of presence in a user study. We also assessed spatial awareness and knowledge gain, and finally obtained feedback from domain experts. Overall, students and professionals rated the application positively. To minimize distraction from interactive learning content, such VRLEs should consider features for different learning types, allow for gradual habituation, and at the same time provide enough playful stimuli. Our work previews how VR can be integrated into a cardiac embryology education curriculum.

Species richness stabilizes productivity via asynchrony and drought-tolerance diversity in a large-scale tree biodiversity experiment.

Extreme climatic events threaten forests and their climate mitigation potential globally. Understanding the drivers promoting ecosystem stability is therefore considered crucial for mitigating adverse climate change effects on forests. Here, we use structural equation models to explain how tree species richness, asynchronous species dynamics, species-level population stability, and drought-tolerance traits relate to the stability of forest productivity along an experimentally manipulated species richness gradient ranging from 1 to 24 tree species. Tree species richness improved community stability by increasing asynchrony. That is, at higher species richness, interannual variation in productivity among tree species buffered the community against stress-related productivity declines. This effect was positively related to variation in stomatal control and resistance-acquisition strategies among species, but not to the community-weighted means of these trait syndromes. The identified mechanisms by which tree species richness stabilizes forest productivity emphasize the importance of diverse, mixed-species forests to adapt to climate change.

Multiple plant diversity components drive consumer communities across ecosystems.

Humans modify ecosystems and biodiversity worldwide, with negative consequences for ecosystem functioning. Promoting plant diversity is increasingly suggested as a mitigation strategy. However, our mechanistic understanding of how plant diversity affects the diversity of heterotrophic consumer communities remains limited. Here, we disentangle the relative importance of key components of plant diversity as drivers of herbivore, predator, and parasitoid species richness in experimental forests and grasslands. We find that plant species richness effects on consumer species richness are consistently positive and mediated by elevated structural and functional diversity of the plant communities. The importance of these diversity components differs across trophic levels and ecosystems, cautioning against ignoring the fundamental ecological complexity of biodiversity effects. Importantly, plant diversity effects on higher trophic-level species richness are in many cases mediated by modifications of consumer abundances. In light of recently reported drastic declines in insect abundances, our study identifies important pathways connecting plant diversity and consumer diversity across ecosystems.

Neighbourhood interactions drive overyielding in mixed-species tree communities.

Theory suggests that plant interactions at the neighbourhood scale play a fundamental role in regulating biodiversity-productivity relationships (BPRs) in tree communities. However, empirical evidence of this prediction is rare, as little is known about how neighbourhood interactions scale up to influence community BPRs. Here, using a biodiversity-ecosystem functioning experiment, we provide insights into processes underlying BPRs by demonstrating that diversity-mediated interactions among local neighbours are a strong regulator of productivity in species mixtures. Our results show that local neighbourhood interactions explain over half of the variation in observed community productivity along a diversity gradient. Overall, individual tree growth increased with neighbourhood species richness, leading to a positive BPR at the community scale. The importance of local-scale neighbourhood effects for regulating community productivity, however, distinctly increased with increasing community species richness. Preserving tree species diversity at the local neighbourhood scale, thus seems to be a promising way for promoting forest productivity.

A high-resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data.

Forest canopies and tree crown structures are of high ecological importance. Measuring canopies and crowns by direct inventory methods is time-consuming and of limited accuracy. High-resolution inventory tools, in particular terrestrial laser scanning (TLS), is able to overcome these limitations and obtain three-dimensional (3D) structural information about the canopy with a very high level of detail. The main objective of this study was to introduce a novel method to analyze spatiotemporal dynamics in canopy occupancy at the individual tree and local neighborhood level using high-resolution 3D TLS data. For the analyses, a voxel grid approach was applied. The tree crowns were modeled through the combination of two approaches: the encasement of all crown points with a 3D α-shape, which was then converted into a voxel grid, and the direct voxelization of the crown points. We show that canopy occupancy at individual tree level can be quantified as the crown volume occupied only by the respective tree or shared with neighboring trees. At the local neighborhood level, our method enables the precise determination of the extent of canopy space filling, the identification of tree-tree interactions, and the analysis of complementary space use. Using multitemporal TLS data recordings, this method allows the precise detection and quantification of changes in canopy occupancy through time. The method is applicable to a wide range of investigations in forest ecology research, including the study of tree diversity effects on forest productivity or growing space analyses for optimal tree growth. Due to the high accuracy of this novel method, it facilitates the precise analyses even of highly plastic individual tree crowns and, thus, the realistic representation of forest canopies. Moreover, our voxel grid framework is flexible enough to allow for the inclusion of further biotic and abiotic variables relevant to complex analyses of forest canopy dynamics.

Anthropogenic nitrogen deposition alters growth responses of European beech (Fagus sylvativa L.) to climate change.

Global change affects the functioning of forest ecosystems and the services they provide, but little is known about the interactive effects of co-occurring global change drivers on important functions such as tree growth and vitality. In the present study we quantified the interactive (i.e. synergistic or antagonistic) effects of atmospheric nitrogen (N) deposition and climatic variables (temperature, precipitation) on tree growth (in terms of tree-ring width, TRW), taking forest ecosystems with European beech (Fagus sylvatica L.) as an example. We hypothesised that (i) N deposition and climatic variables can evoke non-additive responses of the radial increment of beech trees, and (ii) N loads have the potential to strengthen the trees' sensitivity to climate change. In young stands, we found a synergistic positive effect of N deposition and annual mean temperature on TRW, possibly linked to the alleviation of an N shortage in young stands. In mature stands, however, high N deposition significantly increased the trees' sensitivity to increasing annual mean temperatures (antagonistic effect on TRW), possibly due to increased fine root dieback, decreasing mycorrhizal colonization or shifts in biomass allocation patterns (aboveground vs. belowground). Accordingly, N deposition and climatic variables caused both synergistic and antagonistic effects on the radial increment of beech trees, depending on tree age and stand characteristics. Hence, the nature of interactions could mediate the long-term effects of global change drivers (including N deposition) on forest carbon sequestration. In conclusion, our findings illustrate that interaction processes between climatic variables and N deposition are complex and have the potential to impair growth and performance of European beech. This in turn emphasises the importance of multiple-factor studies to foster an integrated understanding and models aiming at improved projections of tree growth responses to co-occurring drivers of global change.

Toward a methodical framework for comprehensively assessing forest multifunctionality.

Biodiversity-ecosystem functioning (BEF) research has extended its scope from communities that are short-lived or reshape their structure annually to structurally complex forest ecosystems. The establishment of tree diversity experiments poses specific methodological challenges for assessing the multiple functions provided by forest ecosystems. In particular, methodological inconsistencies and nonstandardized protocols impede the analysis of multifunctionality within, and comparability across the increasing number of tree diversity experiments. By providing an overview on key methods currently applied in one of the largest forest biodiversity experiments, we show how methods differing in scale and simplicity can be combined to retrieve consistent data allowing novel insights into forest ecosystem functioning. Furthermore, we discuss and develop recommendations for the integration and transferability of diverse methodical approaches to present and future forest biodiversity experiments. We identified four principles that should guide basic decisions concerning method selection for tree diversity experiments and forest BEF research: (1) method selection should be directed toward maximizing data density to increase the number of measured variables in each plot. (2) Methods should cover all relevant scales of the experiment to consider scale dependencies of biodiversity effects. (3) The same variable should be evaluated with the same method across space and time for adequate larger-scale and longer-time data analysis and to reduce errors due to changing measurement protocols. (4) Standardized, practical and rapid methods for assessing biodiversity and ecosystem functions should be promoted to increase comparability among forest BEF experiments. We demonstrate that currently available methods provide us with a sophisticated toolbox to improve a synergistic understanding of forest multifunctionality. However, these methods require further adjustment to the specific requirements of structurally complex and long-lived forest ecosystems. By applying methods connecting relevant scales, trophic levels, and above- and belowground ecosystem compartments, knowledge gain from large tree diversity experiments can be optimized.

Evaluation of Preclinical Assays to Investigate an Anthroposophic Pharmaceutical Process Applied to Mistletoe (Viscum album L.) Extracts.

Extracts from European mistletoe (Viscum album L.) developed in anthroposophic medicine are based on specific pharmaceutical procedures to enhance remedy efficacy. One such anthroposophic pharmaceutical process was evaluated regarding effects on cancer cell toxicity in vitro and on colchicine tumor formation in Lepidium sativum. Anthroposophically processed Viscum album extract (APVAE) was produced by mixing winter and summer mistletoe extracts in the edge of a high-speed rotating disk and was compared with manually mixed Viscum album extract (VAE). The antiproliferative effect of VAE/APVAE was determined in five cell lines (NCI-H460, DU-145, HCC1143, MV3, and PA-TU-8902) by WST-1 assay in vitro; no difference was found between VAE and APVAE in any cell line tested (P > 0.14). Incidence of colchicine tumor formation was assessed by measurement of the root/shoot-ratio of seedlings of Lepidium sativum treated with colchicine as well as VAE, APVAE, or water. Colchicine tumor formation decreased after application of VAE (-5.4% compared to water, P < 0.001) and was even stronger by APVAE (-8.8% compared to water, P < 0.001). The high-speed mistletoe extract mixing process investigated thus did not influence toxicity against cancer cells but seemed to sustain morphostasis and to enhance resistance against external noxious influences leading to phenomenological malformations.

Intravenous magnesium versus nimodipine in the treatment of patients with aneurysmal subarachnoid hemorrhage: a randomized study.

OBJECTIVE: The prophylactic use of nimodipine in patients with aneurysmal subarachnoid hemorrhage reduces the risk of ischemic brain damage. However, its efficacy seems to be rather moderate. The question arises whether other types of calcium antagonists offer better protection. Magnesium, nature's physiological calcium antagonist, is neuroprotective in animal models, promotes dilatation of cerebral arteries, and has an established safety profile. The aim of the current pilot study is to evaluate the efficacy of magnesium versus nimodipine to prevent delayed ischemic deficits after aneurysmal subarachnoid hemorrhage. METHODS: One hundred and thirteen patients with aneurysmal subarachnoid hemorrhage were enrolled in the study and were randomized to receive either magnesium sulfate (loading 10 mg/kg followed by 30 mg/kg daily) or nimodipine (48 mg/d) intravenously until at least postoperative Day 7. Primary outcome parameters were incidence of clinical vasospasm and infarction. Secondary outcome measures were the incidence of transcranial Doppler/angiographic vasospasm, the neuronal markers (neuron-specific enolase, S-100), and the patients' Glasgow Outcome Scale scores at discharge and after 1 year. RESULTS: One hundred and four patients met the study requirements. In the magnesium group (n = 53), eight patients (15%) experienced clinical vasospasm and 20 (38%) experienced transcranial Doppler/angiographic vasospasm compared with 14 (27%) and 17 (33%) patients in the nimodipine group (n = 51). If clinical vasospasm occurred, 75% of the magnesium-treated versus 50% of the nimodipine-treated patients experienced cerebral infarction resulting in fatal outcome in 37 and 14%, respectively. Overall, the rate of infarction attributable to vasospasm was virtually the same (19 versus 22%). There was no difference in outcome between groups. CONCLUSION: The efficacy of magnesium in preventing delayed ischemic neurological deficits in patients with aneurysmal subarachnoid hemorrhage seems to be comparable with that of nimodipine. The difference in their pharmacological properties makes studies on the combined administration of magnesium and nimodipine seem promising.