Patterns of vegetation succession in abandoned fields in semi-arid conditions

Successions in old fields were studied on the example of the Starobilski steppes within Luhansk Oblast (Ukraine), region located in the basin of the left tributaries of the Siversky Donets, in the southern spurs of the Central Russian Upland. Stationary surveys were conducted in the Striltsivsky Steppe affiliate of the Luhansk Nature Reserve, with 269 ha of old fields (26% of the area) in its territory. Geobotanical releves were performed in 26 plots of abandoned fields, constant monitoring surveys were carried out in 15–27 year-old abandoned fields in the territory of the Reserve and 5–15 year-old abandoned fields in the territory of its buffer zone. In total, the itinerary and detailed surveys were conducted for about 50 plots of abandoned fields. The restoration of the steppe communities was seen only in the plots where grazing and/or mowing took place, which prevented the formation of dense litter and distribution of woody species. The long domination of rhizome grasses (Elytrigia repens) were characteristic in conditions of moderate-level disturbance (in the reserve), transition to the domination of bunchgrasses (Festuca valesiaca) was seen at the age of around 25 years, during the transitional period (20–25 years) communities with unstable structure formed, comprising E. repens, F. valesiaca and forbs (Achillea pannonica and Fragaria viridis). Duration of the stage of segetal and ruderal species in the sites under low effect was 10 years, the communities of unstable structure formed at the age of 5–10 years. In the conditions of stable moderate and high effect of grazing (high disturbance), we observed formation of bunchgrass communities at the age of 15 years. In the unused plots, we saw formation of phytocoenoses of shrubs at different stages of succession, starting from 10 years. The most abundant group of such kind comprised thickets of Ulmus pumila (with E. repens and Poa angustifolia in the herbaceous layer) and Prunus stepposa. The peculiarity of contemporary processes in the abandoned fields related to exacerbation of the vegetation’s anthropogenic transformation is distribution of alien tree species from plantations, the most aggressive of which are Ulmus pumila, Fraxinus lanceolata, Acer negundo, Elaeagnus angustifolia. The peculiarity of the succession processes in the region of studies was the domination of species of broad ecological spectrum, characteristic for abandoned fields of northern forest-steppe regions (Bromopsis inermis, Calamagrostis epigeios, Poa angustifolia, Fragaria viridis) and southern steppe regions (Bromus sguarrosus, Anisantha tectorum, Achillea pannonica, Artemisia austriaca), certain communities form dependent on the climatic conditions and type of land use in the period of succession in particular plots.

Functional Traits Plasticity of the Invasive Herb Argemone ochroleuca Sweet in Different Arid Habitats

Understanding the strategies and mechanisms of invasive species could guide their control and management especially in arid ecosystems. This study compares the vegetative and reproductive functional traits of the invasive Mexican poppy (Argemone ochroleuca), in seven habitat types, in southwestern Saudi Arabia. The results showed that the aboveground phenological attributes such as plant height, leaf area, and leaf dry mass attained the highest values in the wadi channels, whereas these attributes attained the lowest values in the mountain ranges. Maximum specific leaf area, root parameters, and all reproductive traits were recorded in the abandoned fields. In contrast to all other habitats, populations from abandoned fields had a greater investment of resources in belowground structures, while the population growing in the wadi channels and mountain ranges habitat allocated more energy to vegetative parts. The plasticity in vegetative and reproductive resource allocation in A. ochroleuca is an important mechanism in determining its colonizing ability in different habitat types and expanding the distribution range. The present data of the functional traits of A. ochroleuca agree with the resource fluctuation hypothesis, where the plant flourished in the abandoned fields that attained the highest values of organic matter and nutrients. Therefore, the restoration of these disturbed habitats could improve the resistance toward invasion by this noxious weed.

Is it possible to replenish oil in abandoned fields due to the interaction of hydrothermal solutions with enclosing bituminous and carbonous rocks? (Experiment with the participation of fluid inclusions)

The article considers the possibilities of oil and gas replenishment in previously worked out fields on the basis of experimental data on the interaction of bituminous and carbonaceous rocks with hydrothermal solutions and the simultaneous growth of quartz with fluid inclusions in them. These solutions can generate and transport oil and gas in pre-critical, sub- and supercritical states. The data obtained confirm the ideas of a number of petroleum geochemists about the migration of liquid hydrocarbons in the Earth’s interior in the form of high-temperature homogeneous, including supercritical fluids, and also explains the possibility of deep metamorphism of oil and the formation of the deepest fields of dry gas and graphite. It is especially important that the results of experimental studies using synthetic water-hydrocarbon inclusions make it possible to state that depleted oil fields can replenish lost oil and gas due to the interaction of hydrothermal solutions with the surrounding host bituminous and carbonaceous rocks.

Intraspecific Variations in Functional and Molecular Traits of Near-Endemic Onopordum alexandrinum Boiss. in Natural and Anthropogenic Habitats along the Western Mediterranean Coast of Egypt: Implications for Conservation

Onopordum alexandrinum is a near-endemic to Egypt and neighboring countries. Its habitats are designated as priority sites for conservation in the south and east Mediterranean regions. We hypothesize that variation in morphological, reproductive, and molecular traits could provide a survival strategy that allows the species to occupy landscapes including anthropogenic habitats (barley and abandoned fields) and natural habitats (sand dunes and desert plateau) with different soil resources along the western Mediterranean coast of Egypt. The results indicated that plant functional traits associated with high rates of resource acquisition and growth (e.g., high values of vegetative height and specific leaf area, and low values of leaf dry matter content) occurred in populations located in abandoned fields with high soil resources. The genetic diversity analyses indicated similarity in genetic diversity of the present populations of O. alexandrinum in barley and abandoned fields with those of sand dunes. However, the genetic structures of these populations were different from those of natural desert plateau, which suggests reduced rates of gene flow. In this framework, it is essential to monitor and reduce the anthropogenic activity which will not only support the conservation of genetic diversity within populations but will also help ensure the resilience of O. alexandrinum in the face of environmental and climatic changes.

Effect of secondary succession in abandoned fields on some properties of acidic sandy soils

<p>Abandonment of agricultural lands in recent decades is occurring mainly in Europe, North America and Oceania, and changing the fate of landscapes as the ecosystem recovers during fallow stage. The objective of this study was to find the impact of secondary succession in abandoned fields on some parameters of acidic sandy soils in the Borská nížina lowland (southwestern Slovakia). We investigated soil chemical (pH and soil organic carbon content), hydrophysical (water sorptivity, and hydraulic conductivity), and water repellency (water drop penetration time, water repellency cessation time, repellency index, and modified repellency index) parameters, as well as the ethanol sorptivity of the studied soils. Both the hydrophysical and chemical parameters decreased significantly during abandonment of the three investigated agricultural fields. On the other hand, the water repellency parameters increased significantly, but the ethanol sorptivity did not change during abandonment. As the ethanol sorptivity depends mainly on soil pore size, the last finding could mean that the pore size of acidic sandy soils did not change during succession.</p>

Low first-year apparent survival of passerines in abandoned fields in northwestern Russia

First-year survival probability of migratory passerines during the period between fledging and first reproduction is a highly variable parameter that has a major effect on population dynamics. We used a long-term mark–recapture dataset (2002–2018) to examine first-year survival of 3 passerine species breeding in abandoned agricultural fields of northwestern Russia: Booted Warbler (Iduna caligata), Whinchat (Saxicola rubetra), and Western Yellow Wagtail (Motacilla flava). We banded 3,457 nestlings, including 1,363 Booted Warblers, 1,699 Whinchats, and 395 Western Yellow Wagtails, and resighted 12 Booted Warblers, 29 Whinchats, and 13 Western Yellow Wagtails in the year after fledging. We evaluated first-year apparent survival rates using Cormack-Jolly-Seber models in MARK program within the multispecies approach. We tested effect of fledge date on the first-year apparent survival. In all focal species, first-year apparent survival rates were low and reached the lower limits known for migratory passerines. We found no differences in first-year survival rates among the 3 species: the estimated average first-year apparent survival rate of all species was 0.05 ± 0.01. The fledge date had a considerable impact on first-year survival rate: later fledge dates negatively affected first-year survival. We suggest that first-year apparent survival rates in our study were low due to low natal philopatry and high mortality in the post-fledging period. Low apparent first-year survival may be a specific feature of open-nesting birds breeding in abandoned fields that are low-quality habitats because of high predation pressure.