Determination of Floral Origin Markers of Latvian Honey by Using IRMS, UHPLC-HRMS, and 1H-NMR

The economic significance of honey production is crucial; therefore, modern and efficient methods of authentication are needed. During the last decade, various data processing methods and a combination of several instrumental methods have been increasingly used in food analysis. In this study, the chemical composition of monofloral buckwheat (Fagopyrum esculentum), clover (Trifolium repens), heather (Calluna vulgaris), linden (Tilia cordata), rapeseed (Brassica napus), willow (Salix cinerea), and polyfloral honey samples of Latvian origin were investigated using several instrumental analysis methods. The data from light stable isotope ratio mass spectrometry (IRMS), ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS), and nuclear magnetic resonance (NMR) analysis methods were used in combination with multivariate analysis to characterize honey samples originating from Latvia. Results were processed using the principal component analysis (PCA) to study the potential possibilities of evaluating the differences between honey of different floral origins. The results indicate the possibility of strong differentiation of heather and buckwheat honeys, and minor differentiation of linden honey from polyfloral honey types. The main indicators include depleted δ15N values for heather honey protein, elevated concentration levels of rutin for buckwheat honey, and qualitative presence of specific biomarkers within NMR for linden honey.

Post fire ground vegetation development over 25 years

Fire has been a part of natural disturbance regime in boreal and to some extent also hemiboreal forests, affecting soil and light conditions, seedbanks, trees and ground vegetation. The most significant factors affecting occurrence, severity and size of forest fires are anthropogenic, weather and the environment, all of which are changing due to human-caused climate change. This paper discusses medium term (25 years) vegetation development in five different biotopes after fire disturbance. Sample plots were established in Slitere Reserve (now National park) in north-western Latvia on areas affected by large fire in 1992. Data were collected in 1993, 2002 and 2017. The aim of the study was to characterize the regeneration and succession of ground vegetation after the fire. In 1993, species such as bog-rosemary (Andromeda polifolia), heather (Calluna vulgaris) and cloudberry (Rubus chamaemorus) were observed in the ground vegetation a year after the fire. In 2002 liverworts appeared, indicating that the bog has acquired more stable and wetter conditions, but in 2017, liverwort mosses were no longer present and the percentage cover of Rubus chamaemorus decreased significantly and Calluna vulgaris, sphagnum sp., and Betula pendula were present in large quantities in the bog. Comparing these studied years, it can be concluded that all these years the biotopes and species have continuously developed and are regenerating.

The Calluna life cycle concept revisited: implications for heathland management

Heather, Calluna vulgaris, is a key species of European dry heath and central determinant of its conservation status. The established Calluna life cycle concept describes four phases—pioneer, building, mature, and degeneration—distinguishable by growth and vitality characteristics of undisturbed plants grown from seeds. However, little is known about the life cycle and ageing of plants subjected to severe disturbance, although measures to this effect (burning, mowing) are common in heathland management. We studied the vitality of over 400 heather plants by examining multiple morphological (plant height, long shoot and inflorescence lengths, flowering activity), anatomical (growth rings) and environmental (management, nitrogen deposition, climate) attributes. We found Calluna vitality to be mainly determined by the aboveground stem age, and that severe disturbances promote vigorous vegetative regeneration. Ageing-related shifts in the habit and vitality of plants resprouting from stem-base buds is similar to that of seed-based plants, but the former revealed higher vitality when young, at the cost of a shorter life span. In contrast, plants originating from decumbent stems resemble building-stage plants but apparently lack the capacity to re-enter a cycle including stages other than degeneration-type. As a consequence, we supplemented the established heather life cycle concept with a post-disturbance regeneration cycle of plants derived from resprouting. We conclude that management of dry lowland heathlands should include rotational small-scale severe disturbance to support both seed germination and seedling establishment as well as vegetative regeneration chiefly of young heather plants capable of resprouting from buds near rootstock.

New data on the status and ecology of a galliform at risk of extinction: the Pyrenean grey partridge (Perdix perdix hispaniensis) in the Iberian System (Soria, Spain)

A study was conducted in 2008–2010 to gain knowledge on the status and ecology of the endangered subspecies of grey partridge (Perdix perdix hispaniensis), at its southernmost range edge. From an historic breeding range of 28,300 ha, 15 different coveys (adults with juveniles) were observed in an area comprising 5,550 ha, with an estimated minimum autumn population size of 103–113 birds and a maximum of 163–181 birds. Spring pair density was estimated at 2.3 pairs/1,000 ha, and when considering only coveys, 6.8 partridges/1,000 ha. The majority of birds were located at an altitude above 1,690 m a.s.l., mainly in mountain shrubland (especially Calluna vulgaris and Erica spp.). Habitat loss was the most important threat for the species’ conservation. In conclusion, efforts should prioritize urgent habitat recovery and monitoring in order to change the fate of the species.

New data on the status and ecology of a galliform at risk of extinction: the Pyrenean grey partridge (Perdix perdix hispaniensis) in the Iberian System (Soria, Spain)

A study was conducted in 2008–2010 to gain knowledge on the status and ecology of the endangered subspecies of grey partridge (Perdix perdix hispaniensis), at its southernmost range edge. From an historic breeding range of 28,300 ha, 15 different coveys (adults with juveniles) were observed in an area comprising 5,550 ha, with an estimated minimum autumn population size of 103–113 birds and a maximum of 163–181 birds. Spring pair density was estimated at 2.3 pairs/1,000 ha, and when considering only coveys, 6.8 partridges/1,000 ha. The majority of birds were located at an altitude above 1,690 m a.s.l., mainly in mountain shrubland (especially Calluna vulgaris and Erica spp.). Habitat loss was the most important threat for the species’ conservation. In conclusion, efforts should prioritize urgent habitat recovery and monitoring in order to change the fate of the species.

European pollen-based REVEALS land-cover reconstructions for the Holocene: methodology, mapping and potentials

Quantitative reconstructions of past land-cover are necessary for research into the processes involved in climate-human-land interactions. We present the first temporally continuous pollen-based land-cover reconstruction for Europe over the Holocene (last 11,700 cal yr BP). We describe how vegetation cover has been quantified from pollen records at a 1° × 1° spatial scale using the ‘Regional Estimates of VEgetation Abundance from Large Sites’ (REVEALS) model. REVEALS has been applied to 1128 pollen records across Europe and part of the Eastern Mediterranean-Black Sea-Caspian-Corridor (30°–75° N, 25° W–50° E) to reconstruct the cover of 31 plant taxa assigned to 12 plant functional types (PFTs) and three land-cover types (LCTs). A new synthesis of relative pollen productivities (RPPs) available for European plant taxa was performed for this reconstruction. It includes > 1 RPP values for 39 taxa, and single values for 15 taxa (total of 54 taxa). As an illustration, we present maps of the results for five taxa (Calluna vulgaris, Cerealia-t, Picea abies, Quercus deciduous and Quercus evergreen) and three LCTs (open land (OL), evergreen trees (ET) and summer-green trees (ST)) for 8 selected time windows. We discuss the reliability of the REVEALS reconstructions and issues related to the interpretation of the results in terms of landscape openness and human-induced vegetation change. We then describe the current use of this reconstruction and its future potential utility and development. The REVEALS data presented here can be downloaded from https://doi.pangaea.de/10.1594/PANGAEA.937075?format=html#download.

Chemical and Antioxidant Characterization of the Portuguese Heather Honey from Calluna vulgaris

The Calluna vulgaris honey produced in Portugal, concerning its phenolic compounds and abscisic acids profiles, as well as its antioxidant activity and the protective effect against oxidative damage in human erythrocytes were herein performed for the first time. The phenolic and abscisic acid profiles were tentatively identified by LC-MS/MS (17 compounds). The total content of phenolics and abscisic acids was 15,446.4 µg/g of honey extract, with catechin derivatives and abscisic acids being major constituents. The highest scavenging capacity was found against reactive nitrogen species. Additionally, the honey extract prevented ROO•-induced oxidative damage in erythrocytes collected from human blood, by inhibiting hemolysis, lipid peroxidation and hemoglobin oxidation. In conclusion, C. vulgaris honey contains high content of catechin derivatives and abscisic acids that may be responsible for its biological activity, characterized by a strong antioxidant capacity, which adds up to the nutritional value of this delicacy.

Characterising the response of plant-mycorrhizal networks to a changing alpine environment

<p>Anthropogenic climate change effects are particularly acute in alpine ecosystems. New Zealand’s alpine regions are experiencing climatic changes at higher than global mean rates, particularly warming and drying. These communities are also facing increasing rates of invasion by exotic plant species. Notably, multiple drivers of change, such as warming and invasion, have been evidenced to interact and facilitate greater ecosystem change. This is of particular concern as New Zealand's alpine plant communities are unique globally and represent national hotspots of biodiversity. Therefore there is a pressing need to understand how they may be affected by the independent and interactive drivers of global environmental change. Alpine plant species form ubiquitous and obligate symbiotic associations with mutualistic mycorrhizal fungi. Plant-mycorrhiza networks are foundational interactions that underpin the diversity and function of terrestrial communities. Plant-mycorrhiza networks are also particularly sensitive to temperature shifts and plant invasions. In this thesis, I investigate the independent and interactive effects of warming and the presence of an invasive species (Common Heather, Calluna vulgaris) on the fungal community composition and the network of mycorrhiza interactions of alpine plants in Tongariro National Park, New Zealand. I sampled the roots of plant species within the Warming and species Removal in Mountains (WaRM) experiment, a factorial combination of warming and Calluna vulgaris removals (n = 8 per treatment) established in TNP in 2015. The plant community at the site consists of plant species that form either arbuscular mycorrhizas or ericoid mycorrhizas. I selected the three most abundant plant species of each mycorrhizal type at the site scale for sampling in each of the 32 plots. DNA was extracted from plant roots, and the internal transcribed spacer of the fungal rRNA gene was amplified by PCR and sequenced on the Illumina Mi-seq platform. Sequence data was demultiplexed and fungal OTUs were identified using the PIPITS pipeline, referencing the UNITE fungal database. In my second chapter, I consider plant species and treatment effects on the diversity and community composition of mycorrhizal fungi. I found WaRM treatments were significant determinants of mycorrhizal compositions in host plant species. Warming simultaneously increased the mycorrhizal fungal diversity and richness of invasive Calluna vulgaris and reduced that of the native host plant species. In chapter 3, using network analyses from the bipartite package of R, I constructed 32 plant mycorrhizal networks of the plot sampled and calculated metrics pertaining to properties of network structure and robustness at the whole network, trophic-level and species/mycorrhizal fungal OTU scales. I then examined the responses of these metrics to the WaRM treatments. I found that warming significantly reduced the robustness of native plant-mycorrhizal networks and increased the strength of the interaction network associated with invasive C. vulgaris. The removal of C. vulgaris had a secondary effect on how mycorrhizal fungal compositions and interaction networks responded to warming. As a generalist C. vulgaris was critical for the ongoing diversity of ericoid mycorrhizal fungi, particularly under warming. However, C. vulgaris simultaneously suppressed the mycorrhizal interaction- networks of native plant species, which further fragmented under warming. I conclude that warming and the presence of invasive C. vulgaris synergistically reduced and decentralised the native plant-mycorrhizal interactions within the network. In summary, my thesis demonstrates the below-ground interactions of alpine plant communities are destabilising under multiple interacting drivers of global environmental change.</p>

Characterising the response of plant-mycorrhizal networks to a changing alpine environment

<p>Anthropogenic climate change effects are particularly acute in alpine ecosystems. New Zealand’s alpine regions are experiencing climatic changes at higher than global mean rates, particularly warming and drying. These communities are also facing increasing rates of invasion by exotic plant species. Notably, multiple drivers of change, such as warming and invasion, have been evidenced to interact and facilitate greater ecosystem change. This is of particular concern as New Zealand's alpine plant communities are unique globally and represent national hotspots of biodiversity. Therefore there is a pressing need to understand how they may be affected by the independent and interactive drivers of global environmental change. Alpine plant species form ubiquitous and obligate symbiotic associations with mutualistic mycorrhizal fungi. Plant-mycorrhiza networks are foundational interactions that underpin the diversity and function of terrestrial communities. Plant-mycorrhiza networks are also particularly sensitive to temperature shifts and plant invasions. In this thesis, I investigate the independent and interactive effects of warming and the presence of an invasive species (Common Heather, Calluna vulgaris) on the fungal community composition and the network of mycorrhiza interactions of alpine plants in Tongariro National Park, New Zealand. I sampled the roots of plant species within the Warming and species Removal in Mountains (WaRM) experiment, a factorial combination of warming and Calluna vulgaris removals (n = 8 per treatment) established in TNP in 2015. The plant community at the site consists of plant species that form either arbuscular mycorrhizas or ericoid mycorrhizas. I selected the three most abundant plant species of each mycorrhizal type at the site scale for sampling in each of the 32 plots. DNA was extracted from plant roots, and the internal transcribed spacer of the fungal rRNA gene was amplified by PCR and sequenced on the Illumina Mi-seq platform. Sequence data was demultiplexed and fungal OTUs were identified using the PIPITS pipeline, referencing the UNITE fungal database. In my second chapter, I consider plant species and treatment effects on the diversity and community composition of mycorrhizal fungi. I found WaRM treatments were significant determinants of mycorrhizal compositions in host plant species. Warming simultaneously increased the mycorrhizal fungal diversity and richness of invasive Calluna vulgaris and reduced that of the native host plant species. In chapter 3, using network analyses from the bipartite package of R, I constructed 32 plant mycorrhizal networks of the plot sampled and calculated metrics pertaining to properties of network structure and robustness at the whole network, trophic-level and species/mycorrhizal fungal OTU scales. I then examined the responses of these metrics to the WaRM treatments. I found that warming significantly reduced the robustness of native plant-mycorrhizal networks and increased the strength of the interaction network associated with invasive C. vulgaris. The removal of C. vulgaris had a secondary effect on how mycorrhizal fungal compositions and interaction networks responded to warming. As a generalist C. vulgaris was critical for the ongoing diversity of ericoid mycorrhizal fungi, particularly under warming. However, C. vulgaris simultaneously suppressed the mycorrhizal interaction- networks of native plant species, which further fragmented under warming. I conclude that warming and the presence of invasive C. vulgaris synergistically reduced and decentralised the native plant-mycorrhizal interactions within the network. In summary, my thesis demonstrates the below-ground interactions of alpine plant communities are destabilising under multiple interacting drivers of global environmental change.</p>