Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2019

Abstract

Repeat photography is an efficient method for documenting long-term landscape changes. So far, the usage of repeat photographs for quantitative analyses is limited to approaches based on manual classification. In this paper, we demonstrate the application of a convolutional neural network (CNN) for the automatic detection and classification of woody regrowth vegetation in repeat landscape photographs. We also tested if the classification results based on the automatic approach can be used for quantifying changes in woody vegetation cover between image pairs. The CNN was trained with 50 × 50 pixel tiles of woody vegetation and non-woody vegetation. We then tested the classifier on 17 pairs of repeat photographs to assess the model performance on unseen data. Results show that the CNN performed well in differentiating woody vegetation from non-woody vegetation (accuracy = 87.7%), but accuracy varied strongly between individual images. The very similar appearance of woody vegetation and herbaceous species in photographs made this a much more challenging task compared to the classification of vegetation as a single class (accuracy = 95.2%). In this regard, image quality was identified as one important factor influencing classification accuracy. Although the automatic classification provided good individual results on most of the 34 test photographs, change statistics based on the automatic approach deviated from actual changes. Nevertheless, the automatic approach was capable of identifying clear trends in increasing or decreasing woody vegetation in repeat photographs. Generally, the use of repeat photography in landscape monitoring represents a significant added value to other quantitative data retrieved from remote sensing and field measurements. Moreover, these photographs are able to raise awareness on landscape change among policy makers and public as well as they provide clear feedback on the effects of land management.

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Abstract

Auxin is a molecule, which controls many aspects of plant development through both transcriptional and non-transcriptional signaling responses. AUXIN BINDING PROTEIN1 (ABP1) is a putative receptor for rapid non-transcriptional auxin-induced changes in plasma membrane depolarization and endocytosis rates. However, the mechanism of ABP1-mediated signaling is poorly understood. Here we show that membrane depolarization and endocytosis inhibition are ABP1-independent responses and that auxin-induced plasma membrane depolarization is instead dependent on the auxin influx carrier AUX1. AUX1 was itself not involved in the regulation of endocytosis. Auxin-dependent depolarization of the plasma membrane was also modulated by the auxin efflux carrier PIN2. These data establish a new connection between auxin transport and non-transcriptional auxin signaling.

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Abstract

Biodiversity of ecosystems is an important driver for the supply of ecosystem services to people. Soils often have a larger biodiversity per unit surface area than what can be observed aboveground. Here, we present what is to our knowledge, the most extensive literature-based key-word assessment of the existing information about the relationships between belowground biodiversity and ecosystem services in European forests. The belowground diversity of plant roots, fungi, prokaryota, soil fauna, and protists was evaluated in relation to the supply of Provisioning, Regulating, Cultural, and Supporting Services. The soil biota were divided into 14 subgroups and the ecosystem services into 37 separate services. Out of the 518 possible combinations of biotic groups and ecosystem services, no published study was found for 374 combinations (72%). Of the remaining 144 combinations (28%) where relationships were found, the large majority (87%) showed a positive relationship between biodiversity of a belowground biotic group and an associated ecosystem service. However, for the majority of the combinations (102) there were only three or fewer studies. The percentage of cases for which a relationship was detected varied strongly between ecosystem service categories with 23% for Provisioning, 8% for Regulating, 40% for Cultural, and 48% for Supporting Services.We conclude that (1) soil biodiversity is generally positively related to ecosystem services in European forests; (2) the links between soil biodiversity and Cultural or Supporting services are better documented than those relating to Provisioning and Regulating services; (3) there is a huge knowledge gap for most possible combinations of soil biota and ecosystem services regarding how a more biodiverse soil biota is associated with a given ecosystem service. Given the drastically increasing societal demand for knowledge of the role of biodiversity in the functioning of ecosystems and the supply of ecosystem services, we strongly encourage the scientific community to conduct well-designed studies incorporating the belowground diversity and the functions and services associated with this diversity.

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Abstract

Recent studies on using soil enhancer material, such as biochar, provide varying results from a soil hydrological and chemical perspective. Therefore, research focusing on soil-biochar-plant interactions is still necessary to enhance our knowledge on complex effects of biochar on soil characteristics. The present study investigated the changes in soil water content (SWC) and soil respiration (belowground CO2 production) over time during the growth of Capsicum annuum (pepper) in pot experiments. Concurrently, we investigated the influence of grain husk biochar with the amount of 0, 0.5%, 2.5%, and 5.0% (by weight) added to silt loam soil. Pepper plants were grown under natural environmental conditions to better represent field conditions, and additional irrigation was applied. SWC among treatments showed minor changes to precipitation during the beginning of the study while plants were in the growing phase. The highest water holding throughout the experiment was observed in the case of BC5.0. CO2 production increased in biochar amended soils during the first few days of the experiments; while the overall cumulative CO2 production was the highest in control and the lowest in BC2.5 treatments. We used the HYDRUS 1D soil hydrological model to simulate changes in SWC, using the control treatment without biochar as a reference data source for model calibration. The simulated SWC dynamics fitted well the measured ones in all treatments. Therefore, the HYDRUS 1D can be an exceptionally valuable tool to predict the hydrological response of different amount of biochar addition to silt loam soil including plant growth.

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Abstract

Mediterranean climate areas are home to highly relevant and distinctive agro-ecosystems, where sustainability is threatened by water scarcity and continuous loss of soil organic carbon. In these systems, recycling strategies to close the loop between crop production (and agrorelated industries) and soil conservation are of special interest in the current context of climate change mitigation. Pyrolysis represents a recycling option for the production of energy and biochar, a carbonaceous product with a wide range of environmental and agronomic applications. Considering that biochar functionality depends on both the original biomass and the pyrolysis conditions, we produced and characterized 22 biochars in order to evaluate their potential to sequester C and modify soil physicochemical properties. The pore size distribution was a function of the original biomass and did not change with the temperature of pyrolysis. The highest number of pores within the size 0.2−30 μm, relevant for plant available water retention, was reached at 600 °C. However, ideal pyrolysis conditions to optimize C stability and hydrologic properties was reached at 400 °C in woody derived biochars, as higher temperatures lead to a nontransient hydrophobicity. This study highlights relevant physicochemical properties of locally derived biochars that can be used to tackle specific challenges in Mediterranean agroecosystems.