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1. The visual landscape of marine and terrestrial systems is changing as a result of anthropogenic factors. Often these shifts involve introduced species that are morphologically dissimilar to native species, creating a unique biogenic structure and habitat for associated species within the landscape. While community-level changes as a result of introduced species have been documented in both terrestrial and marine systems, it is still unclear how long-term shifts in species composition will affect habitat complexity or its potential to influence the biodiversity of species that occur at the base of the food web. 2. We analysed quadrat photos collected at several subtidal sites in the Gulf of Maine over a 30+ year period, and collected individual seaweed species to determine their complexity and the biodiversity of meso-invertebrates associated with each species. 3. By coupling the relationship of 30+ years of shifts in seaweed assemblages, morphological structure of the seaweed assemblage, and their meso-invertebrates, we determined introduced seaweeds have increased by up to 90%, corresponding to a rise in two-dimensional (2D) structure, and a decline in canopy height of subtidal rocky habitats. The highly complex two-dimensional habitat provided by introduced filamentous red seaweeds supports two to three times more meso-invertebrate individuals and species that form the base of the food web than simpler forms of morphological habitat. 4. Synthesis. The present study demonstrates a long-term shift in foundation species towards a dominance of invasive seaweeds that directly reduce canopy height and increase the 2D biogenic structure of the habitat. These introduced seaweeds harbour greater biodiversity of species found at the base of the food web than seaweeds with simpler forms such as the native kelp species. Such shifts in habitat structure will propagate to food webs by influencing the structure of lower trophic-level meso-invertebrates and indirectly upper trophic-level species that feed on these invertebrates and use the seaweed structure as refuge.

Phenology is acknowledged as one of the important traits that contribute significantly to the success of alien species. Differences in the life history traits related to invasive and native vegetation have been shown to influence the success and extent of the plant invasion. Therefore, to obtain this information, we documented and contrasted the duration of key phenological events viz., vegetative, reproductive and senescence between an invasive alien plant species Ageratina adenophora (Sprengel) King and Robinson and associated 29 natives in different habitats viz., Oak, Pine and Cypress forests and grassland. The results indicated vegetative phase and senescence tends to be more synchronised between species than in reproduction. Distinct periodicity in the reproductive phases between A. adenophora and the associated species was observed, with A. adenophora flowering earlier than most of the other species in all habitats. The reproductive cycle of A. adenophora was over before the onset of rainy season which enabled dispersed seeds to optimize the growing condition provided by the rain, giving head start over associated species. Senescence phases in A. adenophora was longest compared to associated species. The observation made in the study may assist in understanding the phenological behavior of A. adenophora and associated species, and may develop a guideline for future mechanistic management of A. adenophora .

As climates change across already stressed ecosystems, there is no doubt that species will be affected, but to what extent and which will be most vulnerable remain uncertain. The fossil record suggests that most species persisted through past climate change, whereas forecasts of future impacts predict large-scale range reduction and extinction. Many species have altered range limits and phenotypes through 20th-century climate change, but responses are highly variable. The proximate causes of species decline relative to resilience remain largely obscure; however, recent examples of climate-associated species decline can help guide current management in parallel with ongoing research.

Sharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwide. Here, we show that nearly two-thirds (59%) of the 134 coral-reef associated shark and ray species are threatened with extinction. Alongside marine mammals, sharks and rays are among the most threatened groups found on coral reefs. Overfishing is the main cause of elevated extinction risk, compounded by climate change and habitat degradation. Risk is greatest for species that are larger-bodied (less resilient and higher trophic level), widely distributed across several national jurisdictions (subject to a patchwork of management), and in nations with greater fishing pressure and weaker governance. Population declines have occurred over more than half a century, with greatest declines prior to 2005. Immediate action through local protections, combined with broad-scale fisheries management and Marine Protected Areas, is required to avoid extinctions and the loss of critical ecosystem function condemning reefs to a loss of shark and ray biodiversity and ecosystem services, limiting livelihoods and food security. Sharks and rays are vital coral reef species. This study shows that nearly two thirds (59%) of the 134 coral-reef associated species are threatened with extinction. The main cause of their decline is found to be overfishing, both targeted and unintentional, and extinction risk is greater for larger species found in nations with higher fishing pressure and weaker governance.

Climate change and habitat destruction have been linked to global declines in vertebrate biodiversity, including mammals, amphibians, birds, and fishes. However, invertebrates make up the vast majority of global species richness, and the combined effects of climate change and land use on invertebrates remain poorly understood. Here we present 35 years of data on 159 species of butterflies from 10 sites along an elevational gradient spanning 0-2,775 m in a biodiversity hotspot, the Sierra Nevada Mountains of Northern California. Species richness has declined at half of the sites, with the most severe reductions at the lowest elevations, where habitat destruction is greatest. At higher elevations, we observed clear upward shifts in the elevational ranges of species, consistent with the influence of global warming. Taken together, these long-term data reveal the interacting negative effects of human-induced changes on both the climate and habitat available to butterfly species in California. Furthermore, the decline of ruderal, disturbance-associated species indicates that the traditional focus of conservation efforts on more specialized and less dispersive species should be broadened to include entire faunas when estimating and predicting the effects of pervasive Stressors.

1. The true status of many endangered plants is uncertain because the locations of all extant populations are not known. Species distribution models (SDMs) can direct searches for additional populations, but habitat fragmentation may influence the distribution of rare species more than climatic or edaphic factors in human-dominated landscapes. In this study, I test the ability of SDMs to predict rare plant occurrences in a fragmented landscape and the importance of predicted habitat suitability versus landscape context. 2. I built SDMs for eight rare woodland plants and assessed them using an independent data set including plant community surveys of 51 sites. I used community data to determine whether SDMs predict the right habitat type even when the target rare species was absent. I then modelled rare species presence based on predicted habitat suitability, distance to the nearest known population and the amount of forest habitat within 500 m of the site. 3. SDMs were effective for seven of the eight species, with the degree of predicted habitat suitability positively related to species' occurrence. I found new populations of four of the eight species. However, the amount of forest habitat available in the vicinity of a plot was also a positive predictor of rare plant occurrences. Among sites predicted to be suitable, the distance to the nearest known population was the strongest predictor of rare plant occurrence. 4. Synthesis and applications. Species distribution models (SDMs) can effectively target searches for populations of rare species even in human-dominated landscapes. Surveying the plant community at sites predicted to be suitable can help to improve the SDM. SDMs used in conjunction with data on landscape context can maximize the efficiency of searches for rare species and show which species are restricted by dispersal limitation and habitat fragmentation in addition to edaphic and climatic factors.

Complex distribution data can be summarized by grouping species with similar or overlapping distributions to unravel spatial patterns and separate trends (e.g., of habitat loss) among spatially unique groups. However, such classifications are often heuristic, lacking the transparency, objectivity, and data‐driven rigor of quantitative methods, which limits their interpretability and utility. Here, we develop and illustrate the clustering of spatially associated species, a methodological framework aimed at statistically classifying species using explicit measures of interspecific spatial association. We investigate several association indices and clustering algorithms and show how these methodological choices drive substantial variations in clustering outcomes and performance. To facilitate robust decision‐making, we provide guidance on choosing methods appropriate to one's study objective(s). As a case study, we apply our framework to modeled tree distributions in Borneo and subsequently evaluate the impact of land‐cover change on separate species groupings. Based on the modeled distribution of 390 tree species prior to anthropogenic land‐cover changes, we identified 11 distinct clusters that unraveled ecologically meaningful patterns in Bornean tree distributions. These clusters then enabled us to quantify trends of habitat loss tied to each of those specific clusters, allowing us to discern particularly vulnerable species clusters and their distributions. This study demonstrates the advantages of adopting quantitatively derived clusters of spatially associated species and elucidates the potential of resultant clusters as a spatially explicit framework for investigating distribution‐related questions in ecology, biogeography, and conservation. By adopting our methodological framework and publicly available codes, practitioners can leverage the ever‐growing abundance of distribution data to better understand complex spatial patterns among species distributions and the disparate effects of global changes on biodiversity.

Parthenium hysterophorus L. has become a weed of global concern owing to its fast expansion and invasive character. In order to study the status of this noxious weed and its impact on floristic diversity in Dhauladhar foothills, the study was conducted during the year 2021–2022 in culturable wastelands of Dhauladhar ranges in Kangra district of Himachal Pradesh, India. The impact of Parthenium hysterophorus L. on associated species at different altitudes and aspects was observed. Our observations depicted that Parthenium hysterophorus L. has been growing more vigorously in the northern aspect than the southern aspect with the density of 37.78 m −2 and 21.62 m −2 , respectively. The highest density of this noxious weed was recorded in the altitudinal range of 600–1200 m (34.32 m −2 ) while it was not observed beyond 1805 m above sea level. The invasion of Parthenium hysterophorus L. significantly affected the plant density of other species. The descending order of the species as per dominance was observed as Cynodon dactylon , Trifolium repens , Oxalis latifolia , Parthenium hysterophorus L., and Ageratum houstonianum . The average number of species and species density were observed more in non-invaded sites (9.35 and 27.67 m −2 ) than in invaded sites (7.10 and 20.60 m −2 ). Species abundance and plant cover were observed more in non-invaded sites (28.73 and 657.90 m 2  ha −1 ) than in invaded sites (22.70 and 322.30 m 2  ha −1 ). Species diversity, richness, and evenness were reported to decline in invaded sites (1.56, 0.95, and 0.81, respectively) with respect to the non-invaded sites (1.94, 1.16, and 0.88, respectively). The study highlights the significant concerns associated with the invasive weed within the plant communities. Understanding its invasive status holds considerable implications for local afforestation initiatives, forest management strategies, and conservation policies. Furthermore, this investigation lays a foundational groundwork for implementing effective measures to get rid of this alien weed.

Aim Human development and agriculture can have transformative and homogenizing effects on natural systems, shifting the composition of ecological communities towards non‐native and native species that tolerate or thrive under human‐dominated conditions. These impacts cannot be fully captured by summarizing species presence, as they include dramatic changes to patterns of species abundance. However, how human land use patterns and species invasions intersect to shape patterns of abundance and dominance within ecological communities is poorly understood even in well‐known taxa. Location Conterminous United States. Time period 2010–2012. Major taxa studied Passeriformes. Methods We analyse continental‐scale monitoring data to study the proportional abundance of non‐native and native synanthropic species within passerine bird communities. Synanthropic species are those that benefit from an association with humans. We estimate how the amount and configuration of human development and agriculture relate to the degree to which human‐associated species dominate passerine communities across the continent. Results Human‐associated species comprised the majority of detected passerine individuals across two‐thirds of bird surveys. Non‐native and synanthropic species responded differently to land cover and reached highest relative abundance in different portions of the continent. The proportional abundance of synanthropic birds increased rapidly with development, but was not related to the configuration of land cover. The proportion of non‐native individuals was higher when intensively‐used land cover was more aggregated. Main conclusions Even low amounts of intensively‐used lands were associated with a dramatic reshaping of passerine communities, with consequences for patterns of relative abundance across the continent.

Little is known about the importance of different tree species in maintaining diversity and function. To address this, we fogged 99 trees (30 Fraxinus excelsior , 30 F. pennsylvanica , 21 Quercus robur , 12 Ulmus laevis and 6 Tilia cordata ) in Elbe floodplain forests, resulting in 182,179 arthropods including 25,861 (14.2%) beetles. Ninety-two percent of all beetles and 65% of all species were canopy associated. Tourist beetles of the ground contributed 35% to the arboreal richness but only 8% to overall abundance, suggesting little influence on trophic interactions. The highest alpha and beta diversity was recorded on Fraxinus trees, mainly due to the high number of tourists in low abundance. On the contrary, Quercus or Ulmus were characterised by large numbers of associated species. The beetle communities, and even more so the entire communities of all orders, were dominated by predators, suggesting strong top-down control of herbivore populations. Phytophages were significantly more abundant on Quercus and Ulmus , while they represented less than 10% on the ashes. F. excelsior is a keystone species, and this includes the ability to maintain biodiversity and communities with different functional profiles. As a result of ash dieback and drought, F. excelsior has been severely reduced in these forests. Our extensive data show that F. excelsior and F. pennsylvanica are similar in many ecological features due to their taxonomic relationship, resulting in a similar diversity and functional composition of arthropod communities, indicating that F. pennsylvanica can at least partially fill the ecological role of the common ash.