Can we leave it to nature? – post-fire tree regeneration in Białowieża Forest

Abstract:In the south-eastern Amazon, positive feedbacks between land use and severe weather events are increasing the frequency and intensity of fires, threatening local biodiversity. We sampled fruit-feeding butterflies in experimental plots in a south-eastern Amazon forest: one control plot, one plot burned every 3 y, one plot burned yearly. We also measured environmental parameters (canopy cover, temperature, humidity). Our results show no significant differences in overall species richness between plots (34, 37 and 33 species respectively), although richness was lower in burned plots during the dry season. We found significant differences in community composition and structure between control and burned plots, but not between burned treatments. In the control plot, forest-specialist species represented 64% of total abundance, decreasing to 50% in burned every 3 y and 54% in yearly burned plots. Savanna specialist species were absent in the control plot, but represented respectively 8% and 3% of total abundance in burned plots. The best predictor of the change in spatial community patterns and abundance of forest specialists was canopy cover. Although we found high resilience to forest burning in many species, our study suggests that fire disturbance can still be a threat to forest specialists due to changes in microclimate.

Slopes of an abandoned waste rock at Wangaloa coal mine, south-east New Zealand, have naturally developed variable vegetation cover over the last 40–60 years. Three distinct areas of revegetation can clearly be identified: dense cover, patchy cover, and largely unvegetated, and the differences in revegetation success are directly related to the physical properties of different rock types making up the waste rock substrate. The colonizing plants have become established in largely unweathered rock with essentially no soil development. Quartz gravel and siltstone waste rock are the two principal rock types forming substrates for revegetation. The quartz gravel has clasts up to 3 cm, and was derived from the coal-bearing sequence. Siltstone was largely derived from a Quaternary loess cap on the coal mine area. These two substrates have similar mineral contents, and this mineral material provides the low level of available nutrients. However, there is little difference in nutrient status or trace element load of the different substrates, and differences in cohesion, moisture content, and proportion of quartz pebbles control revegetation success. Finer grained matrix has been flushed from quartz gravel waste rock by rain water, leaving a dry surface armour layer of quartz pebbles. This surface layer inhibits plant establishment, so quartz gravel waste rock remains largely unvegetated. Erosion creates deep rills, and steep surfaces creep downslope. In contrast, full vegetation cover was established on the siltstone waste rock that was cohesive and did not erode. Patchy revegetation was localized by siltstone in mixed quartz gravel and siltstone substrate. Invertebrate diversity and distribution were closely linked to the spatial patterns of revegetation. The rate of revegetation and ecosystem recovery was primarily dependent on the proportion of siltstone waste rock in the last dumped truck load. A quartz pebble content <15% is optimal for plant establishment.

The objects of study are Hylocomiosa forest site forests owned by government and managed by JSC �Latvia�s State Forests�. Research object is a part of forest protection zone around cities. In those protection zones clear-cut is forbidden by law. In order to promote forest growth and mitigate the negative effects of climate change, forests in protected zones also need to be properly managed. The aim of research is to evaluate regeneration success of Scots pine Pinus sylvestris L after group selection felling in Hylocomiosa forest site type. The data required for the research were obtained by establishing 25 m2 sample plots in five research objects: three of those research objects are after first step of group selection felling and two objects after the first step of overall selection felling. An annual height increases of Scots pine (starting from the second year) was measured in the sample plots of the first group selection felling openings (0.2 ha) and the number of trees was determined in one four-year-old and two biennial young stands. The heights of Scots pines were measured and compared in the four year old group selection felling site and in two overall selection felling sites by evenly establishing sample plots on the longest diagonal of the research area. The prediction of the next group felling step by registering at least one meter high Scots pine was done. The study found that in the Hylocomiosa forest site by artificial regeneration the area with Scots pine, both - two and four years after regeneration, the number of trees per hectare is sufficient. The increase of the height and annual height of Scots pine in the second year after restoration are similar among sites. It is potential to predict the time period after which the next step of selection felling will be possible. The natural regeneration of Scots pine under canopy of the remaining stand takes twice as long as artificial regeneration in gaps after group selection felling.

In recent years, large wildfires have spread in Arctic regions as a consequence of ongoing climate change. Arctic organic soils are comparatively shallow but may be ancient, thus thousands of years old carbon may be released in smoldering and deeply burning fires. In Greenland, a land known for its icy expanse, fires are extremely rare. However, in summer 2019, the second-largest wildfire ever recorded on the island occurred at the Kangerluarsuk Tulleq fjord in southwestern Greenland. This study aims to produce pioneering in-field data on this tundra fire, focusing on three key aspects: 1) combustion, 2) burn depth, and 3) the age of the carbon released. Understanding whether the released carbon is modern or old is crucial due to different implications for the global carbon cycle and climate. To estimate carbon losses from the Kangerluarsuk Tulleq tundra fire, we established 14 sampling plots in burned areas and at unburned control sites. The selection of sampling plots was guided by a differenced Normalized Burn Ratio (dNBR) map generated using Sentinel-2 data and field reconnaissance. Within each plot, we assessed fire severity to estimate the above-ground carbon loss. For below-ground carbon loss estimation and burn depth analysis, organic soil samples were collected at burned plots and compared with unburned ones. To explore the vegetation succession and burned vegetation type, organic soil profiles (n=10) were extracted down to the mineral ground using a soil box corer and were studied by light-microscopy. Subsamples (n=20) from burned soil horizons were selected for radiocarbon dating to determine the age of carbon released in the fire. Our preliminary results suggest that soil carbon loss was higher than previously reported at an Alaskan tundra fire site with a mean value of 6.718 &amp;#177; 0.9 kg of C m-2. The mean burn depth was 9.0 &amp;#177; 1.8 cm, and soil thaw depths during the 2024 summer were approximately 24 cm deeper in the 2019 burned area compared to unburned tundra. Expected radiocarbon results will indicate the maximum age of the carbon released by the fire. Vegetation succession measurements show that post-fire surfaces were predominantly colonized by pioneering non-Sphagnum bryophytes, Cyperaceae, and Ericaceae. The acquired results are first of a kind from a Greenland tundra fire and produce essential data for global climate modeling to assess the climate impacts of increasing Arctic wildfires.

We studied responses of soil microarthropods to different burning intensities at a clearcut that was burnt in May 2002. Fire intensity was manipulated by adding or removing logging residues as fuel from the experimental plots. Samples were taken 1 week before and 1 week after burning as well as during autumn of the same year. Samples were taken in the 2 following years to estimate long-term recovery. No difference in humus combustion could be detected between burning intensities, but most microarthropod species showed lower abundances in the hard-burnt than in the light-burnt plots immediately after fire. Surface-living species also declined in light-burnt plots, whereas soil-living species were particularly affected in hard-burnt plots. This is probably explained by greater heat transfer into the hard-burnt soil. Total abundances of Oribatida and Protura remained low for several years in the burnt plots, whereas abundances of Collembola and Mesostigmata recovered within 1 year, which indicates that at least these groups had enough habitat space and food resources after fire. The study indicates that fire severity (depth of burn) is more decisive than fire intensity (heat release) for the long-term recovery of soil fauna, whereas fire intensity determines the acute survival of animals.

In 1975 and 1976, an experimental burning program was conducted in an immature stand of boreal jack pine (Pinus banksiana Lamb.) growing on level, granitic outwash sands in northern Ontario. Nine 0.4-ha plots were burned under a range of fire weather conditions and sampling was conducted to examine the effect of fire on soil chemical changes and revegetation. Results indicated that depth of burn (DOB) affected both soil chemical changes and plant succession on these pine sites. Vaccinium angustifolium Ait., Oryzopsis spp,. Waldsteinia fragarioides (Michx.) Tratt, Salix spp. and Viola adunca Sm. increased in cover at two levels of DOB but the increase was greatest at the lower DOB and decreased to pre-burn levels after 10 yr. Comptonia peregrina (L.) Coult., Epilobium angustifolium L., Polytrichum commune Hedw. and Amelanchier sanguinea (Pursh) DC. were not found in the pre-burn surveys but appeared after burning. Vegetation cover for these species was always higher at the deeper DOB but decreased almost to zero after 10 yr. Other species such as Pleurozium schreberi (Brid.) Mitt., Linnaea borealis L., Corylus cornuta Marsh., Cladina rangiferina (L.) Nyl. and Aralia nudicaulis L. were eliminated from the site and did not recover even after 10 yr. Soil pH increased 0.3 to 1.0 pH units in the organic and mineral soil layers. The rate of increase in pH was always steeper at the higher DOB and pH returned to pre-burn levels in the mineral soil layers after 10 yr. Immediately after burning, exchangeable Ca in the mineral soil layers doubled but 10 yr later, Ca returned to pre-burn levels. Phosphorus and K increased in the mineral soil, leveled off and were still elevated after 10 yr. Total Kjeldahl N was reduced by 50% in the organic soil while N in all mineral soils increased, and was still increasing after 10 yr. Except for immediate post-fire increases in pH, Ca and N, soil chemical changes were small or they rebounded to pre-burn levels 10 yr after burning. Therefore it is unlikely that these changes were the cause of the plant cover changes that persisted to 10 yr. Key words: Soil nutrients, plant succession, fire, depth of burn, jack pine

Vegetation fires are among the most dangerous natural hazards. In Croatia, they are most common on the Adriatic coast and in the areas near the Adriatic, especially in summer when the peak of the fire season occurs. Meteorological risk of vegetation fires in Croatia is primarily assessed with the Canadian Forest Fire Weather Index and derived fire danger. However, due to the rare spatial and temporal availability of these data as well as the effects of climate change resulting in frequent enhanced fire danger during the summer, the need for additional risk assessment tool has emerged. In that sense, the fire weather warnings were introduced ten years ago and since then have been constantly improved and adapted to the needs of the firefighting community. The aim is to warn of weather conditions that can lead to the rapid spread and unpredictable behavior of the vegetation fires. As a basic condition, fire weather warnings are issued when the fire danger classes from the Canadian Forest Fire Weather Index are high and very high. Except the meteorological parameters of the Fire Weather Index, the most important of which is wind, the behavior and spread of vegetation fires can be further influenced by atmospheric turbulence and instability in the dry air near the ground and in the lower atmosphere. These parameters also depend on the orography of the terrain and are not included in the Fire Weather Index. Two years ago, three levels of warnings were defined, the thresholds of which depend on the values and duration of wind, turbulence and instability. In addition to the detailed explanation of the method for issuing fire weather warnings, the paper presents textual and graphical warning examples, describes five critical fire weather patterns when conditions for issuing warning are the most common, and in the end gives a brief overview of warnings statistics and the most recent evaluation. According to the feedback from the firefighting community, the warnings proved to be important in the organization of supervisory and preventive activities, as well as fire suppression activities in case of vegetation fire ignition. The evaluation also shows that most of the significant vegetation fires burned in the days and at the locations for which warnings were issued.

Observed and estimated consequences of climate change for the fire weather regime in the moist-temperate climate of the Czech Republic

Resilience to fire and climate seasonality drive the temporal dynamics of ant-plant interactions in a fire-prone ecosystem

Climate change and its impact on economic and social well-being is an important current issue that is being studied everywhere in the modern world. Acceleration of economic growth due to mass production, increasing the level of welfare of society and increasing the population, led to an increase in production volumes, which in turn caused a further rapid increase in waste generation and carbon dioxide emissions. Today, manufacturers around the world are faced with the need to apply such business practices that would be focused on protecting the environment by reducing environmentally harmful waste on a global scale, and consumers - understanding the importance of economical and repeated consumption, preserving biodiversity and protecting the environment on the path to sustainable development. The study substantiates that it is the circular economy that will combine two key tasks - ensuring economic development and mitigating the effects of climate change. Thanks to this economic model, which reduces environmental pollution, reduces greenhouse gas emissions, minimizes the use of resources for economic growth, due to the fact that they are constantly reused, recycled or repurposed, and not thrown away as waste, it is possible to leave a more livable world for future generations. The study found a significant correlation between the implementation of circular economy practices and the objectives of the Sustainable Development Goals, in particular in terms of minimizing CO2 emissions. A complex relationship between CO2 emissions and gross domestic product, which occupies a central place in environmental economics and climate change research, was established. At the level of individual regions of Ukraine, the feasibility of studying the relationship between carbon dioxide emissions and indicators such as gross regional product, sales volumes and population density was substantiated. It was found that almost all regions of Ukraine that demonstrate high growth rates of GRP per capita are observed in the same growth in CO2 emissions. This is consistent with the priorities of the circular economy, which is to minimize resource extraction by encouraging reuse, recycling and remanufacturing. Regions with higher population densities have been found to have lower levels of CO2 emissions, which is explained by the fact that higher population densities often lead to more compact urban environments. Higher population densities can facilitate economies of scale in infrastructure development, such as energy-efficient buildings, district heating and waste management systems.

Breeding bird communities were studied by line-transect in burnt pinewood and unburnt pinewoods, during three years subsequently to a fire event, in a coastal woodland of Mediterranean central Italy. We analyzed data following a diversity/dominance approach that ranks the species in order of their abundance, to obtain rank/abundance diagrams (‘Whittaker plots’). Although it is generally accepted that fire may induce structural changes in forest communities of breeding birds, we observed more evident effects when considering the assemblage of forest-specialist species. When considering the whole community of birds, ordinate intercepts of the regression between rank and relative abundance of species were not significantly different between unburnt and burnt plots in any of the three years of study. However, when considering only the forest-related species, there was a significant difference between unburnt and burnt plots in all the years of study. Evenness showed lower values that were explicited by the diversity/dominance diagrams (lower collocation of the curves of burnt pinewoods if compared to unburnt ones). Overall, the patterns observed in this study suggest that the effects of fire disturbance were more evident at the ecological level than at the taxonomic-level assemblages. The gradual decline of the more sensitive species due to fires and the proportional increase of edge/generalist species may induce a species turnover in burnt woods with cascade and relaxation effects which could be evidenced by diversity/dominance diagrams. Consequently, it is useful to separate the effects of fires at community-level and at assemblage-level when studying bird communities in areas subjected to fires.

Providing sustainable energy access is one of the most critical global challenges. Both developed and developing nations depend on a variety of primary energy sources like coal, natural gas, biomass, oil and renewable energy to produce electricity. Following the power deficit that was experienced in Zambia between 2015 and 2017 the government has been doing everything possible to develop a diversified renewable energy sector that will play a pivotal role in the provision of alternative sources of energy in the country. However, the intensifying levels of load shedding forced domestic consumers to resort to alternative sources of energy such as; charcoal, generators and gas stoves. This paper assesses the consumption and sustainability of alternative energy sources in high and low density population areas in Lusaka and focusing on households. The study was done on a representative sample of Lusaka from two areas namely Kabulonga, and Chawama representing low and high density respectively. Data was obtained through administering questionnaires to household heads. Results showed that energy consumption behaviour of households varies from one region to another and not all factors are equally important in determining energy consumption in different areas and regions. It was also revealed that the energy consumption decision is affected by economic factors such as market price of fuel, household income, household expenditures and noneconomic factors which include; a set of household characteristics such as household size, gender, education, house ownership, type of dwelling, location of residence, household age, distance to fuel source, and access to electricity. The results showed that 36% respondents in Kabulonga use electricity against 31.1% in Chawama, 29% use gas in Kabulonga against 26% in Chawama. It was noted that more respondents in Chawama use solar at 8.9% against 2% in Kabulonga and also that those that use charcoal in Chawama were 26.7% more than the Charcoal users in Kabulonga at 11%. While the government of Zambia is working on resolving power challenges that the country recently faced, building more hydropower stations has remained their focus. These major hydropower developments will not likely solve the power deficit or climate change effects being experienced such as low water levels due to droughts.

Wildfire frequency and extent is increasing throughout the boreal forest-tundra ecotone as climate warms. Understanding the impacts of wildfire throughout this ecotone is required to make predictions of the rate and magnitude of changes in boreal-tundra landcover, its future flammability, and associated feedbacks to the global carbon (C) cycle and climate. We studied 48 sites spanning a gradient from tundra to low-density spruce stands that were burned in an extensive 2013 wildfire on the north slope of the Alaska Range in Denali National Park and Preserve, central Alaska. We assessed wildfire severity and C emissions, and determined the impacts of severity on understory vegetation composition, conifer tree recruitment, and active layer thickness (ALT). We also assessed conifer seed rain and used a seeding experiment to determine factors controlling post-fire tree regeneration. We found that an average of 2.18 ± 1.13 Kg C m-2 was emitted from this fire, almost 95% of which came from burning of the organic soil. On average, burn depth of the organic soil was 10.6 ± 4.5 cm and both burn depth and total C combusted increased with pre-fire conifer density. Sites with higher pre-fire conifer density were also located at warmer and drier landscape positions and associated with increased ALT post-fire, greater changes in pre- and post-fire understory vegetation communities, and higher post-fire boreal tree recruitment. Our seed rain observations and seeding experiment indicate that the recruitment potential of conifer trees is limited by seed availability in this forest-tundra ecotone. We conclude that the expected climate-induced forest infilling (i.e. increased density) at the forest-tundra ecotone could increase fire severity, but this infilling is unlikely to occur without increases in the availability of viable seed.

The impact of Mount Pinatubo’s 1991 eruption on the traditional use of natural resources by the indigenous Aeta was devastating. The damage resulted in the immediate and sustained disconnection of traditional knowledge from the biological resources integral to practice that knowledge. The relatively slow ecosystem recovery a full 20 years after the event hinders the transfer of traditional knowledge to younger generations of Aeta. Their traditional knowledge is at risk of disappearing from the cultural fabric of the Philippines. In seeking to adapt, decisions by the Aeta to accept the development of foreign-designed ecotourism enterprises may negatively affect natural ecosystem recovery. Alternatives to the existing ecotourism practices may be warranted to safeguard Aeta traditional knowledge.

Recovery of indigenous species subsequent to the clearing of invasive alien plants (IAPs) is crucial for ecosystem recovery to occur. However, cleared sites are often just left in the hope that revegetation will occur naturally. In riparian areas of Kruger National Park (KNP), the Working for Water (WfW) Programme has cleared IAPs on a regular basis, but little post-clearance monitoring has taken place. Thus investigating short-term effects of IAPs and IAP clearing on plant community diversity and vegetation recovery provided an ideal opportunity to assess feasible targets of natural ecosystem recovery in similar areas. Vegetation was sampled from twelve transects along the Sabie River in and adjacent to the KNP, before (March/April 2006) and after (March 2007) the annual clearing of IAPs by WfW. Rarefied species richness, alpha diversity and evenness of distribution of species all declined with increasing density of IAPs ( P < 0.05). There was a mean reduction in IAP density of 80% (S.E ± 6%) ( P = 0.002) through the clearing by WfW. After clearing of IAPs, indigenous vegetation densities increased, with herbaceous growth forms showing the largest increase in transects that were previously heavily invaded. Thus, in this system, which is relatively undisturbed by human activities, initial recovery of indigenous vegetation can occur without further restorative interventions. This process is more than likely aided by the continuous clearing of IAPs by WfW as this acts to deplete alien seed banks and maintain IAPs at acceptable and manageable levels.