ABSTRACT Aims This study presents EcoNetMap, a network‐based framework that uses species co‐occurrence alone to build a fixed reference landscape with a common coordinate system in which species, plots, habitat types and datasets can be located and compared. It functions analogously to a geographic map: Distances encode ecological similarity, and directions correspond to environmental gradients. Location Demonstrated using Danish data, but the framework is applicable to any vegetation monitoring dataset. Methods Applied to Denmark's NOVANA dataset (43 terrestrial habitat types, > 140,000 plots), 12 candidate reference maps were constructed from stratified and random subsamples of the data using two layout algorithms (Fruchterman–Reingold and classical multidimensional scaling) and six sampling strategies. Each candidate was evaluated against four complementary evaluation metrics on independent data, and a weighted composite score was used to select the optimal configuration. In the selected map, species occurring in at least 10 plots formed the core network, whereas sub‐threshold species were positioned on the basis of their associations with core taxa. The resulting reference landscape served as a fixed coordinate system for analysing the complete dataset. Results Environmental gradients in light, moisture, nitrogen and soil reaction emerged from the co‐occurrence data alone, with no environmental variables used in construction (mean adjusted R 2 = 0.686, p < 0.001), and life forms, community clusters, forest shade categories and habitat types all occupied coherent, ecologically interpretable regions of the landscape. The reference network placed 1019 species in a single frame: a densely connected core of 819 species (> 125,000 edges) with moderate modularity (Q = 0.143), consistent with the continuous, gradient‐like nature of Danish vegetation rather than sharply bounded communities. The same frame resolved ecological structure across scales, from individual species through habitat types to whole dataset and biogeographic profiles. Of 12 candidate maps, the Fruchterman–Reingold layout on a stratified 750‐plot‐per‐habitat sample gave the best composite score (0.496); a classical multidimensional scaling comparison confirmed the layout choice rather than the sampling was decisive. Conclusion The EcoNetMap framework contributes to vegetation analysis by translating complex co‐occurrence patterns into a visual reference landscape that reveals ecological structure difficult to detect with traditional methods, including community modularity, core‐periphery specialisation and continuous gradients within and between habitat types. Requiring only standard species occurrence data, it works alongside existing ordination and classification approaches and integrates readily with established monitoring programmes, offering a scalable tool for comparative vegetation analysis and conservation assessment, and a stable frame against which compositional change can be tracked over time.
Questions There is growing evidence of plant invasions in high-elevation mountain ecosystems, but how these invasion patterns relate to native species diversity remains understudied. While the biotic resistance hypothesis states that highly diverse communities are less likely to be invaded than less diverse ones, the opposite pattern might arise from facilitative interactions in harsh environments, if these prevail at high elevations, especially in the alpine zone. Here, we investigate whether the relationship between native and non-native plant species diversity changes with elevation, and whether it is modified by disturbance resulting from mountain roads.Location Global.Methods By using standardized vegetation surveys and plant trait measurements, we modeled the relationship between non-native species richness and native species richness and functional diversity across elevation gradients, and whether they differ between (semi-)natural habitats and adjacent disturbed roadside habitats.Results At high elevations, we recorded more non-native species in functionally diverse natural habitats and in species-rich roadside habitats. At lower elevations, non-native and native species richness were positively associated, but fewer non-native species established in functionally diverse natural habitats. Lateral spread of non-native species from disturbed roadsides into natural habitats occurred with the same frequency at high and low elevations.Conclusions Our results suggest that once non-native species reach high elevations along dispersal corridors such as roads, native plant diversity may help promote, rather than inhibit, their spread into natural plant communities, contradicting the biotic resistance hypothesis. While the positive correlation between non-native and native species richness likely relies on beneficial environmental heterogeneity promoting both species groups, the seemingly inhibiting effect of native functional diversity at low elevations and its assumed supporting role at high elevations might reflect biotic processes such as limiting similarity and facilitation. This suggests that a complex interplay between native diversity and human disturbances shapes the invasibility of mountain ecosystems.
ABSTRACT Aims In alpine regions of Japan, forest vegetation is shaped by both temperature and snow conditions. However, recent rapid warming has emerged as the dominant driver of forest change. This study assessed the effects of climate warming on forest dynamics along an elevational gradient on Mt. Tateyama. Location Mt. Tateyama, Northern Alps, central Japan. Methods We established four permanent plots in the following forest zones: temperate, ecotone, subarctic, and timberline, located at 1090, 1430, 1970, and 2250 m above sea level, respectively. Forest dynamics were examined in relation to trends in temperature and snow conditions from 1998 to 2024. Results Snow cover conditions remained largely unchanged over the study period, whereas temperature increased significantly. According to Kira's warmth index by the 1991–2020 mesh climate normals, the Ecotone plot was classified as ecotone but had shifted to a temperate classification by the end of the study period. Total basal area increased in all plots. However, in the Ecotone plot, the basal area ratio (stand‐based) of temperate and subarctic tree species showed contrasting trends, increasing and decreasing, respectively. The mortality rate of Abies mariesii , the dominant subarctic tree species, was significantly higher in the Ecotone plot than in the other plots, with numerous dead individuals observed across all diameter classes at the beginning of the study. In contrast, at the Timberline plot, A. mariesii exhibited both a large increase in basal area (species‐based) and population growth, characterized by high basal area growth and low mortality rates. Conclusions These results suggest that climate warming is driving an upward shift in forest zones in mountainous regions. The decline of A. mariesii in the Ecotone plot and its population growth at the Timberline plot indicate an ongoing altitudinal redistribution of subarctic tree species.
ABSTRACT Questions Facilitation is a common phenomenon that underlies the local abundance and distribution of many plants. Facilitation can arise via multiple mechanisms, and classes of mechanistic effects have the potential to modulate one another's effects. We quantified two mechanisms by which trees may facilitate understory plants: amelioration of abiotic conditions and herbivory reduction. Location Kenya. Methods We quantified the spatial association of a common forb, Hibiscus meyeri, with tree canopies in an East African savanna in the presence and absence of large mammalian browsers across an aridity gradient. Namely, we compared the observed proportion of H. meyeri under a tree canopy and their distance to the tree canopy to null distributions derived from simulated landscapes. We also used a spatially naïve linear model approach to test for site and exclosure treatment effects on the probability of being under a tree canopy and on distance to canopy. Results Both our randomization and linear model approach suggested that both aridity and herbivore presence increased H. meyeri individuals' association with the tree canopy, suggesting trees facilitate H. meyeri via both abiotic habitat amelioration and herbivory reduction. In addition, herbivore presence more strongly increased H. meyeri 's association with the tree canopy at the arid site, suggesting that facilitative effects of abiotic habitat amelioration could be modulating those of herbivory reduction. Conclusions We found that trees facilitate H. meyeri via multiple facilitative mechanisms. Our results suggest that the strength of one facilitative mechanism can depend on whether other facilitative mechanisms are also operating.
ABSTRACT Aims In this study, we present a novel workflow for the relocation of quasi‐permanent vegetation plots during resurveys in topographically complex environments, such as mountain regions. Location Western Italian Alps, Gran Paradiso National Park. Methods This standardized workflow integrates historical plot site data and descriptions, digital elevation models (DEMs), and in‐field expert knowledge to identify the most suitable sites for plot relocation, even when precise geographical coordinates are unavailable. The resulting methodology is fully reproducible, thanks to the application of an entirely open‐source workflow. The performance of the relocation method was evaluated in terms of both precision and reproducibility among operators during the pre‐fieldwork steps by means of generalized and linear mixed‐effects models. In addition, by performing an ecological case study, the applicability of the workflow was demonstrated by quantifying pseudoturnover through comparison among four independent plot replicas and with historical data from alpine grasslands. Results The proposed workflow proved to be effective in supporting plot relocation, showing good reproducibility among operators. Moreover, it resulted in lower levels of pseudoturnover compared to those reported as acceptable in previous resurvey studies while substantially reducing the effort required for plot relocation in the field. Conclusions This method has the potential to facilitate the execution of large resurvey campaigns by enabling the sampling of single plot replicas rather than multiple ones, as previously recommended. Nevertheless, we recommend identifying a subset of plots for conducting replicate surveys within the identified suitable area, in order to empirically estimate spatial pseudoturnover and further enhance the robustness of resurvey‐based studies.
