Biology subjects

Korznikov, K.

Publications and source records attributed to Korznikov, K..

4 recordsLinked to original sources

bioRxiv2026

Fast and Reliable: Evaluating Smartphone LiDAR App for Stem Diameter Measurement and Tree Mapping

Tree inventories require rapid, accurate measurements of stem diameter at breast height (DBH) and precise tree locations to support monitoring, planning, and informed decision-making. We evaluated a smartphone-based LiDAR app (SBLA), Forest Scanner, against (i) a diameter tape for DBH and (ii) a Vertex ultrasonic device for spatial coordinates. Across DBH of 725 trees, the LiDAR closely matched diameter tape measurements: discrepancies >5 cm occurred in 10.5% and > 10 cm in 3.5% of trees. Errors were concentrated in trees with smaller DBH, where occasional overestimation by SBLA arose from point-cloud misfitting. For medium and large trees, agreement was consistently high. Tree coordinates from SBLA and the ultrasonic device were broadly comparable at fine scales. Field efficiency was substantially improved: a 1,000 m2 plot with 70-80 trees required [~]2 hours using an ultrasonic device and diameter tape versus [~]20 minutes (one person) with SBLA, an [~]85-90% reduction in person-hours. Current limitations of SBLA are primarily software-related (stability, data handling, low-light performance). Overall, SBLA offers an efficient, auditable, and operationally relevant tool for tree inventories, with utility for rapidly updating DBH and spatial data used in management, planning, and asset databases.

ecology↗

bioRxiv2025

When parasites bite hardest: mistletoe effects on oak radial growth peak near climatic optima

Hemiparasitic mistletoes can alter host water and carbon balance, but their impact on tree growth is expected to vary with phenology, microclimate and stand context. We asked whether the yellow mistletoe Loranthus europaeus shifts the timing or reduces the magnitude of radial growth in Quercus robur, and whether any penalty is strongest near climatic optima for host growth. We instrumented 34 mature oaks across age (young, old), canopy position (solitary, closed-canopy), and infection (infected, non-infected) with point dendrometers at 15-minute intervals for four growing seasons (2020-2023). Air and soil temperatures and soil moisture were logged concurrently. We derived growth phenology, difference curves (non-infected minus infected), monthly climate-growth correlations, and response surfaces in temperature- moisture space. Growth phenology was consistent among years: onset around day-of-year 120-140, peak 150-220, cessation 250-270. Mistletoe did not shift onset or cessation but reduced growth amplitude, especially in high-growth years and solitary, well-lit trees. Suppression was greatest near climatic optima ({approx}10-18 {degrees}C with adequate soil moisture) and diminished when conditions were suboptimal (hot and dry or cold and wet), so infected and non-infected converged. Short-term climate-growth relationships were similar across infection status: temperature effects were negative during the main season, whereas soil moisture effects were positive. Young, solitary, non-infected trees responded more to mid-summer moisture than infected trees, consistent with infection shifting hosts from resource-tracking to stress-limited growth under exposure. Joint temperature-moisture response surfaces for infected versus non-infected trees were highly similar, indicating that mistletoe reduces growth magnitude, not niche. Our results identify the environmental window in which host-parasite competition bites hardest and provide a baseline for forecasting parasite impacts under shifting temperature and moisture regimes. Because the largest penalties arise near growth optima, the frequency of cool, moist periods may modulate impacts at the stand scale, particularly for solitary oaks at woodland-grassland ecotones. Integrating fine-scale growth with microclimate clarifies when hemiparasites depress performance and why effects vary across years, sites and canopy contexts. Results underscore the value of continuous dendrometer records for quantifying parasite impacts.

ecology↗

bioRxiv2025

Elevational Shifts in Tropical Tree Leaf Traits: Interactions Between Soil, Climate, Light, and Phylogeny

Understanding how tropical trees respond to complex environmental gradients is essential for predicting forest resilience under climate change. We examined variation in key leaf traits, including specific leaf area (SLA), foliar nitrogen (N) and phosphorus (P), C:N and N:P ratios, and stable isotope composition ({delta}13C, {delta}15N), in 160 tree species along a 3,200-m elevational transect on Mount Cameroon. This gradient spans hyper-humid coastal rainforests to arid Afroalpine savannas, capturing sharp transitions in climate, soils, and forest structure. Leaf traits shifted nonlinearly with elevation, from acquisitive strategies at mid-elevations to conservative syndromes in lowlands and highlands. Mid-elevation forests ([~]1,000-1,500 m), characterized by moderate climate and canopy disturbance by elephants, supported nutrient-rich, high-SLA foliage. In contrast, high-elevation forests (>2,000 m) exhibited low SLA, high C:N, and enriched {delta}13C, consistent with stress tolerance under cold, dry, and fire-prone conditions. The strongest phosphorus limitation occurred in hyper-humid lowlands, where extreme rainfall (>12,000 mm/year) drives leaching losses. Foliar {delta}15N declined markedly with elevation (from +5{per thousand} to -5{per thousand}), indicating a shift from mineral N uptake and N-fixation in lowland Fabaceae to ecto- and ericoid mycorrhizal associations in montane Ericaceae. A bimodal {delta}15N pattern, with enrichment in both lowland and upper montane forests, reflects N-fixation under leaching and fire-driven N scarcity, respectively. Phylogenetic analyses showed that climate, soils, forest structure, and lineage jointly shaped trait-environment relationships. Traits related to {delta}13C, C:N, and {delta}15N exhibited strong phylogenetic signal, highlighting evolutionary constraints. These findings underscore the value of integrating functional traits, isotopes, and phylogeny to predict tropical forest responses to global change.

plant biology↗

bioRxiv2025

A new map of South Manchurian mixed forests facilitates the estimation of their area for conservation purposes

QuestionsSouth Manchurian mixed forests (SMMFs) are among the most species-rich forest ecosystems in the worlds temperate zone. These forests are experiencing significant degradation and have largely been replaced by secondary forests or agricultural lands and anthropogenic non-forest vegetation. A precise quantitative assessment of the remaining forest area is crucial due to their high conservation value. This study aims to assess the current area of these forests and evaluate changes over a historical period. LocationKorean Peninsula, northeastern China, and southern Primorsky Krai in Russia. MethodsWe used the original SMMFs distribution dataset, including vegetation releves, literature on the distribution of these forests, and regional small-scale maps, to create a training set for classifying satellite data. We used Landsat Analysis Ready Data (1997-2001 and 2017-2021) as the basis for mapping. Mapping accuracy and area were estimated using a random stratified sampling, and forest changes were evaluated. Original releves and literature sources were used to verify SMMFs distribution. ResultsThe total area of SMMFs was estimated at 2,791.5{+/-}1,496.2 km{superscript 2}, with significant uncertainty due to limited data from North Korea. Our results indicate that 45% of SMMFs are located in North Korea, 32% in Russia, 20% in China, and 3% in South Korea. Although historical declines in SMMF area have been documented, no significant changes were detected over the past 20 years. In 2021, SMMFs are highly fragmented ecosystems, primarily associated with protected areas. ConclusionsWe developed a high-accuracy (0.97{+/-}0.03) map of mixed forests using remote sensing techniques. This map facilitates the identification of valuable temperate forest regions and enhances understanding of current forest distribution. Our map is essential for planning restoration and conservation efforts for these critical ecosystems.

ecology↗