Repositório da Universidade dos Açores
Repositório Institucional da Universidade dos Açores
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The proper middle class: assessing the importance of subordinate species on plant community assembly and functional diversity
Publication . Ulrich, Werner; Matthews, Thomas; Biurrun, Idoia; Aleksanyan, Alla; Borovyk, Dariia; Burrascano, Sabina; Campos, Juan Antonio; Chusova, Olha; Czarniecka-Wiera, Marta; Czortek, Patryk; Dembicz, Iwona; Essl, Franz; Janišová, Monika; Labadessa, Rocco; Napoleone, Francesca; Pielech, Remigiusz; Vynokurov, Denys; Puchałka, Radosław; Peres-Neto, Pedro
ABSTRACT: The local species abundance distribution (SAD) and the associated distributions of species functional traits (TADs) both result from the process of plant community assembly. Community assembly has been extensively studied for dominant and rare plants, while subordinates, the species of intermediate abundance in a community, have received less research attention although this group is comparatively species rich and important for community functioning. Here, we study the functional role of subordinate species (those covering the intermediate 50% of abundance ranks) using a large data set of Palearctic dry and semi-dry grassland plant communities and data on specific leaf area, seed mass and plant height. Our findings indicate that species rank orders of SADs and TADs tend to be negatively correlated, causing the TAD to have higher evenness than the associated SAD. Subordinate species represented on average less than 15% of total plant abundance and trait space. Functional diversity of subordinates was lower than expected by a null model that assumed an equiprobable random distribution of trait values among plant species. Climate seasonality and elevation appeared to be the most important drivers of subordinate abundance and functional diversity. We conclude that subordinates differ from dominants in trait composition, leading to their partial functional independence from dominants.
Heightened extinction risk due to tropical cyclones in insular biodiversity hotspots
Publication . Valle, Simon; Pereira, David; Matthews, Thomas; Martin, Thomas
ABSTRACT: Tropical Cyclones (TCs) represent a serious and potentially growing threat to global biodiversity, although spatial patterns in the severity of this threat are poorly explored. We provide the first global-scale analysis of TC-related extinction risk by examining both their frequency and the number of species they directly threaten in insular biodiversity hotspots; widely recognized spatial units representing both exceptional biodiversity and elevated threat. We first identified which insular hotspots possessed a theoretically high TC-related extinction risk by plotting 50 years of storm tracks for severe (category 4 and 5) TCs (STCs) and determined the frequency with which they occur within each insular hotspot. We then used IUCN Red List data to determine numbers of terrestrial vertebrates in each ‘high risk’ insular hotspot considered to be directly threatened with extinction by STCs. Five insular hotspots (Japan, Polynesia-Micronesia, Philippines, Madagascar and the Indian Ocean Islands, Caribbean Islands) were identified as being ‘high risk’, together accounting for >95 % of STCs falling within insular hotspots. However, the numbers of TC-threatened species in these hotspots varied greatly, from 128 in the Caribbean Islands (which encountered the fewest STCs of all ‘high risk’ hotspots) to eight in Japan (which received the most STCs). Results therefore indicate that TC-related extinction risk is not related to STC frequency, and other ecological and geographical factors are likely to be important drivers of risk. Regardless, our results show that several insular hotspots, particularly the Caribbean Islands, support many species at immediate risk of TC-driven extinction, and these require urgent conservation action. We advocate for the creation of an IUCN task force to oversee conservation strategies aimed at preventing extinctions of severely range-restricted storm-threatened species. We provide a watchlist of 60 such species with a particularly high risk of extinction which should be the initial focus for such a working group.
BioTIME 2.0: Expanding and Improving a Database of Biodiversity Time Series
Publication . Dornelas, Maria; Matthews, Thomas; Zvuloni, Assaf; Davies, Jonathan
ABSTARCT: Motivation - Here, we make available a second version of the BioTIME database, which compiles records of abundance estimates for species in sample events of ecological assemblages through time. The updated version expands version 1.0 of the database by doubling the number of studies and includes substantial additional curation to the taxonomic accuracy of the records, as well as the metadata. Moreover, we now provide an R package (BioTIMEr) to facilitate use of the database.
Main Types of Variables Included - The database is composed of one main data table containing the abundance records and 11 metadata tables. The data are organised in a hierarchy of scales where 11,989,233 records are nested in 1,603,067 sample events, from 553,253 sampling locations, which are nested in 708 studies. A study is defined as a sampling methodology applied to an assemblage for a minimum of 2 years.
Spatial Location and Grain - Sampling locations in BioTIME are distributed across the planet, including marine, terrestrial and freshwater realms. Spatial grain size and extent vary across studies depending on sampling methodology. We recommend gridding of sampling locations into areas of consistent size.
Time Period and Grain - The earliest time series in BioTIME start in 1874, and the most recent records are from 2023. Temporal grain and duration vary across studies. We recommend doing sample-level rarefaction to ensure consistent sampling effort through time before calculating any diversity metric.
Major Taxa and Level of Measurement - The database includes any eukaryotic taxa, with a combined total of 56,400 taxa.
Software Format - csv and. SQL.
The what, how, and why of trait-based analyses in ecology
Publication . Guilherme, Thomas; Cardoso, Pedro; Jørgensen, Maria Wagner; Mammola, Stefano; Matthews, Thomas; Brook, Barry
ABSTRACT: Functional diversity is increasingly used alongside taxonomic diversity to describe populations and communities in ecology. Indeed, functional diversity metrics allow researchers to summarise complex occupancy patterns in space and/or time across communities and/or populations in response to various stressors. In other words, investigating what, how, and why something is changing in an ecosystem by looking at changes of patterns under a certain process through a specific mechanism. However, as the diversity of functional diversity metrics and methods increases, it is often not directly clear which metric is more readily appropriate for which question. We studied the ability of different functional diversity metrics to recover patterns and signals from different processes linked to common assembly mechanisms in community ecology, such as environmental filtering, competitive exclusion, equalising fitness, and facilitation. Using both simulated data and an empirical dataset affected by more complex and nuanced mechanisms, we tested the effectiveness of different space occupancy metrics to recover the simulated or empirical changes. We show that different metrics perform differently when trying to capture signals from different approximations of common mechanisms relative to no mechanism at all (null). For example, competition was harder to disentangle from the null mechanisms compared to facilitation in our simulations. This emphasises the importance of not using a one-size-fits-all metric. Instead, researchers should carefully consider and test whether a particular metric will be effective in capturing a pattern of interest.
Effect of Row Spacing in the Period Prior to Weed Interference in Peanut Cultivation Under Azorean Conditions
Publication . Parreira, Mariana; Costa, Vasco Rafael Rodrigues; Lopes, David João Horta; de Portugal e Vasconcelos, João Martim; da Silva Madruga, João; Benedito, Vitor Adriano; Campalle, Arthur Nardi; Martins, Heytor Lemos
ABSTRACT: Peanut cultivation currently plays a minor role in Portuguese agriculture, despite the country’s favorable soil and climatic conditions. In the Azores archipelago, where agriculture is a key economic activity, peanut production has recently sparked interest among rural producers. Weeds pose a major threat to crop development, particularly for short-cycle species like peanuts. This study aimed to determine the period prior to weed interference (PPI) in peanut crops under two row spacings (40 cm and 60 cm) on São Miguel Island, Azores. Eight treatments were established—0–15, 0–30, 0–45, 0–60, 0–75, 0–90 days after emergence (DAE), full-season coexistence, and a weed-free control—to represent increasing periods of weed competition. A randomized block design with four replicates was used for each spacing. The weed community included eight species, with Cyperus spp., Digitaria spp., Amaranthus blitum, and Portulaca oleracea being the most prevalent. Weed interference throughout the entire cycle led to yield losses exceeding 81% and 86% at 40 cm and 60 cm row spacings, respectively. The PPI was defined at a 5% yield reduction threshold, which is a commonly accepted benchmark in weed science to determine the beginning of the critical period of weed interference.