Immediate Effects of Prescribed Burning on Soil Mite (Acari: Oribatida) Communities in a Scots Pine (Pinus Sylvestris) Forest, Latvia

Prescribed burning is used to maintain and restore habitats, to protect and increase species bio-diversity. Knowledge about soil fauna is limited, especially on community responses to fire disturbances. The aim of this study was to determine the immediate effects of prescribed burning on soil armoured mite (Acari: Oribatida) communities, vegetation cover and soil physiochemical properties in a boreal Scots pine forest in Latvia. Soil samples were collected on the day of the prescribed burning in the protected landscape area “Ādaži” and 16 days after. No significant changes in abiotic factors were found. Fire significantly decreased the vegetation cover. After the burning, the total number of oribatid mites decreased by 93%, and the number of species by 77%. Changes in oribatid mite communities were significantly influenced by fire severity. The number of individuals decreased among all taxa, except Brachychthonioidea spp. and Cosmochthonius lanathus. A significant decrease in abundance was observed in previously abundant species — Suctobelbella spp., Oppiella nova and Tectocepheus velatus. After the burning, Suctobelbella spp. was an eudominant and Tectocepheus spp. was a dominant genus.

Characterization of the resilience and variability of vegetation during the Holocene using a large database of pollen data

<p>Global climatic changes which are expected in the 21<sup>st</sup> century are likely to create unparalleled disturbances on vegetation. In addition, human activities also increase the risk of fire disturbances and insect epidemies. We investigate the resilience of different biomes by examining their behaviour during the Holocene using a taxonomically harmonized and temporally standardized global fossil pollen datasets,synthesized from 2821 palynological records from the Neotoma Paleoecology Database and additional literature. Specifically, we study the composition variability on millennial time-scale and timescale-dependant scaling of variability from centennial to multi-millennial timescales. A principal component analysis was performed in order to characterize the principal modes of variability of the pollen assemblages. We find coherent regional signals of vegetation variability and scaling of variability from the pollen assemblages, indicating significant millennial scale variability which can be related to vegetation taxa and climates. Particularly, we observe more stability in North America and Northern Europe in areas dominated by boreal forest and deciduous forests. This may be linked to the greater stability of forest ecosystems and also a more stable climate over these areas which may be the result of stabilizing feedbacks. We find that diversity plays a key role in vegetation composition and that more diverse regions allow for greater variability. </p><p> </p><div> <div> </div> </div>

Abiotic forest disturbances in Europe: mapping distribution and trends from space

<div><span>Abiotic forest disturbances are an important driver of ecosystem dynamics around the globe. In Europe, storms and fires have been identified as the most important abiotic disturbances. Yet, how strongly these agents drive local disturbance regimes compared to other agents (e.g., biotic, human) remains unresolved. Furthermore, whether storms and fires are responsible for the observed increase in forest disturbances in Europe is debated. We here provide a first quantitative assessment of storm and fire disturbances in Europe 1986-2020 using Landsat remote sensing data. For more than 30 million disturbance patches mapped across Europe, we determined whether they were caused by storm or fire, using a random forest classifier and a large reference dataset of true disturbance occurrence. Differentiation between abiotic and other disturbances was made possible by using a set of neighborhood metrics, describing the spatial autocorrelation of each disturbance patch within its local surrounding landscape. This approach allowed for mapping both storm and fire disturbances in a spatially explicit manner. The maps show high correlation with national data and local case studies, but provide a seamless wall-to-wall picture of abiotic disturbance distribution. We subsequently analyzed patterns of abiotic disturbance prevalence (i.e., the share of storm and fire disturbances on the overall area disturbed) in space and time. Storm- and fire-related disturbances each accounted for approximately 7 % of all disturbances recorded in Europe in the period 1986-2020. Storm-related disturbances were most prevalent in western and central Europe, and especially mountain regions, where they locally account for >50% of all canopy disturbances. We however also identified storm-related disturbance hotspots in south-eastern and eastern Europe. Fire-related disturbances were a major driver of forest dynamics in southern and south-eastern Europe, but individual fires also occurred in eastern and northern Europe. Only very limited areas in Europe were affected by disturbances of both agents. The prevalence of storm-related disturbances increased over time. No trend in the prevalence of fire-related disturbances was detected, but several high-intensity fire years related to local drought conditions could be identified. We conclude that abiotic disturbances are an important driver of forest dynamics in Europe, but that their influence varies substantially by region. Our analyses suggest that an increase in storm-related disturbances could be an important driver of Europe’s changing forest disturbance regimes, but weaker evidence is present for fires.</span></div>

Short communication: Savanna-forest boundary on Mount Rinjani, Lombok Island, West Nusa Tenggara, Indonesia

Sutomo, van Etten E, Iryadi R. 2021. Short communication: Savanna-forest boundary on Mount Rinjani, Lombok Island, West Nusa Tenggara, Indonesia. Biodiversitas 22: 726-731. Seasonally dry tropical forests tend to be bordered by or are mixed with savanna ecosystems. This research investigates the location and nature of forest-savanna boundary on Mt. Rinjani and hypothesizes on potential causes of such boundary formation. The field survey locations were based on MODIS burnt area data. We made 30 plots (50 x 50 m) established along transects to obtain vegetation and environment data across boundaries. For data analysis, we use community correspondence index (CCI), vegetation composition using Importance Value Index (IVI), and Analysis of Similarity (ANOSIM) to detect differences in floristic and environmental characteristics across boundaries. Species composition in the transition zone (based on highest IVI results) comprises Ficus septica, Macaranga tanarius, Lindera sp., Engelhardia spicata, Saurauria sp., Rytidosperma penicillatum, and Athyrium sp. The Non-Metric Multi-Dimensional Scaling (NMDS) based on environmental data showed clear separation between savanna and forest, although boundaries were floristically similar to forest. Micro- and macro-environmental factors, as well as, fire disturbances, are also important features of the forest-savanna boundary on Mt. Rinjani. We present evidence of boundary dynamics in the form of forest advance on the Mt. Rinjani south-west slope.