Marco Malavasi

University of Sassari | UNISS · Faculty of Mathematics, Physics and Natural Sciences

In the face of rapid biodiversity loss, attention has been increasingly focused on the application of maps towards the challenges of protecting biodiversity. However, biodiversity maps can lead, or have led us into, errors since they are too often not questioned by ecologists, who perceive them as an objective and legitimate representation of the n...

Shrub encroachment in alpine and subalpine environments has raised concerns in recent decades, particularly due to climate change and shifts in land use. This study investigates the varying impacts of shrub invasion on different alpine and subalpine herbaceous communities and analyzes the spatial characteristics of shrub invasion. Three sites in th...

Vegetation structure data are essential for understanding the functioning of terrestrial ecosystems and for informing various science-policy interfaces. Recent years have seen a growing demand for high-resolution data on vegetation structure, driving the prediction of such metrics at fine resolutions (1 m - 30 m) at state, continental, and global s...

Global mapping of forest height is an extremely important task for estimating habitat quality and modeling biodiversity. Recently, three global canopy height maps have been released, the global forest canopy height map (GFCH), the high‐resolution canopy height model of the Earth (HRCH), and the global map of tree canopy height (GMTCH). Here, we ass...

The availability of biodiversity databases is expanding at unprecedented rates. Nevertheless, species occurrence data can be intrinsically biased and contain uncertainties that impact the accuracy and reliability of biodiversity estimates. In this study, we developed a reproducible framework to assess three dimensions of bias-taxonomic, spatial, an...

We present the dataset "SArdinian GRAsslands" (SAGRA), a collection of georeferenced vegetation surveys sourced from different areas of Sardinia (Italy). SAGRA addresses a geographic gap in current databases, as plots from Sardinian grasslands are underrepresented. We collected vegetation data from different projects and organized it within a frame...

Species distribution models (SDMs) have proven valuable in filling gaps in our knowledge of species occurrences. However, despite their broad applicability, SDMs exhibit critical shortcomings due to limitations in species occurrence data. These limitations include, in particular, issues related to sample size, positional uncertainty, and sampling b...

Invasive alien plants (IAPs) are a great challenge for biodiversity conservation and management. Multi-temporal landscape analysis has a great potential for describing plant invasion, however conservation solutions accounting of landscape dynamics are still limited. This research aims to explore the spatial-temporal pattern of the IAP Carpobrotus s...

Shrub encroachment in alpine and subalpine environments has raised concerns in recent decades, particularly due to climate change and shifts in land use. This study investigates the varying impacts of shrub invasion on different alpine and subalpine herbaceous communities and analyzes the spatial characteristics of shrub invasion. Three sites in th...

To identify areas of high biodiversity and prioritize conservation efforts, it is crucial to understand the drivers of species richness patterns and their scale dependence. While classified land cover products are commonly used to explain bird species richness, recent studies suggest that unclassified remote-sensed images can provide equally good o...

The Mediterranean Basin has historically been subject to alien plant invasions that threaten its unique biodiversity. This seasonally dry and densely populated region is undergoing severe climatic and socioeconomic changes, and it is unclear whether these changes will worsen or mitigate plant invasions. Predictions are often biased, as species may...

Mediterranean grasslands stand out as biodiversity hotspots due to their inclusion of diverse habitats that foster a remarkable range of biological diversity, characterized by inter-annual variability of floristic composition. This study aims to assess the inter-annual dynamics of the floristic composition in a grassland within a typical silvopasto...

Biodiversity monitoring is constrained by cost- and labour-intensive field sampling methods. Increasing evidence suggests that remotely sensed spectral diversity (SD) is linked to plant diversity, holding promise for monitoring applications. However, studies testing such a relationship reported conflicting findings, especially in challenging ecosys...

Species distribution models (SDMs) have proven valuable in filling gaps in our knowledge of species occurrences. However, despite their broad applicability, SDMs exhibit critical shortcomings due to limitations in species occurrence data. These limitations include, in particular, issues related to sample size, positional error, and sampling bias. I...

Biodiversity monitoring is crucial for ecosystem conservation, but ground data collection is limited by cost, time, and scale. Remote sensing is a convenient approach providing frequent, near-real-time information with fine resolution over wide areas. According to the Spectral Variation Hypothesis (SVH), spectral diversity (SD) is an effective prox...

Aim Assessing how different sampling strategies affect the accuracy and precision of species response curves estimated by parametric species distribution models. Major Taxa Studied Virtual plant species. Location Abruzzo (Italy). Time Period Timeless (simulated data). Methods We simulated the occurrence of two virtual species with different eco...

Ecological processes are often spatially and temporally structured, potentially leading to autocorrelation either in environmental variables or species distribution data. Because of that, spatially-biased in-situ samples or predictors might affect the outcomes of ecological models used to infer the geographic distribution of species and diversity....

Species distribution models (SDMs) have become a common tool in studies of species–environment relationships but can be negatively affected by positional uncertainty of underlying species occurrence data. Previous work has documented the effect of positional uncertainty on model predictive performance, but its consequences for inference about speci...

Incorporating archaeology within the ecosystem services (ES) framework can offer decision‐makers lessons from the past and a broader sustainability perspective. Given the claimed archaeology‐ES link, the island of Sardinia (Italy) offers an unparalleled opportunity where a unique archaeological heritage occurs in an area of high biodiversity value....

Maps represent powerful tools to show the spatial variation of a variable in a straightforward manner. A crucial aspect in map rendering for its interpretation by users is the gamut of colours used for displaying data. One part of this problem is linked to the proportion of the human population that is colour blind and, therefore, highly sensitive...

Aim: Assessing how different sampling strategies affect the accuracy and precision of species response curves estimated by parametric Species Distribution Models. Major taxa studied: Virtual plant species. Location: Abruzzo (Italy). Time period: Timeless (simulated data). Methods: We simulated the occurrence of two virtual species with different ec...

There is a lack of guidance on the choice of the spatial grain of predictor and response variables in species distribution models (SDM). This review summarizes the current state of the art with regard to the following points: (i) the effects of changing the resolution of predictor and response variables on model performance; (ii) the effect of cond...

Aim: In species distribution models (SDMs), the quality and quantity of data describing the species distribution determine the quality of the estimate of the species-environment relationship. However, SDMs usually rely on opportunistic datasets sampled from existing projects/repositories with different purposes than modelling the distribution of th...

Spatio-ecological heterogeneity is strongly linked to many ecological processes and functions such as plant species diversity patterns and change, metapopulation dynamics, and gene flow. Remote sensing is particularly useful for measuring spatial heterogeneity of ecosystems over wide regions with repeated measurements in space and time. Besides, de...

In the light of unprecedented planetary changes in biodiversity, real-time and accurate ecosystem and biodiversity assessments are becoming increasingly essential for informing policy and sustainable development. Biodiversity monitoring is a challenge, especially for large areas such as entire continents. Nowadays, spaceborne and airborne sensors p...

Ecosystem structure, especially vertical vegetation structure, is one of the six essential biodiversity variable classes and is an important aspect of habitat heterogeneity, affecting species distributions and diversity by providing shelter, foraging, and nesting sites. Point clouds from airborne laser scanning (ALS) can be used to derive such deta...

Maps represent powerful tools to show the spatial variation of a variable in a straightforward manner. A crucial aspect in map rendering for its interpretation by users is the gamut of colours used for displaying data. One part of this problem is linked to the proportion of the human population that is colour blind and, therefore, highly sensitive...

Biodiversity monitoring is crucial for ecosystem conservation, yet field data collection is limited by costs, time, and extent. Remote sensing represents a convenient approach providing frequent, near-real-time information over wide areas. According to the Spectral Variation Hypothesis (SVH), spectral diversity (SD) is an effective proxy of environ...

Biodiversity monitoring is an almost inconceivable challenge at the scale of the entire Earth. The current (and soon to be flown) generation of spaceborne and airborne optical sensors (i.e., imaging spectrometers) can collect detailed information at unprecedented spatial, temporal, and spectral resolutions. These new data streams are preceded by a...

The performance of species distribution models (SDMs) is known to be affected by analysis grain and positional error of species occurrences. Coarsening of the analysis grain has been suggested to compensate for positional errors. Nevertheless, this way of dealing with positional errors has never been thoroughly tested. With increasing use of fine‐s...

As the twenty-first century unfolds, the human-driven decline of life on Earth is of greater concern and, despite tremendous growth in the volume of conservation science and many local successes, shows no clear signs of improvement. As a matter of fact, the reversal of nature’s ongoing decline is only possible with urgent “transformative change”How...

Italy banned the sale of plastic cotton buds, which is one of the most abundant litter items entering the sea and then washing ashore. However, since the ban came into force, no studies have been carried out to assess whether the measure has actually led to the reduction of plastic cotton buds accumulating on Italian coasts. Here we aim at evaluati...

Question Vegetation around the alpine–treeline ecotone faces changes in both climate and land use (i.e. grazing abandonment). Broad‐scale shrub encroachment is considered an effect of these changes, but it remains unclear how this process is mediated by local‐scale environmental heterogeneity. Our goal is to determine which local‐scale environmenta...

The representation of a land cover type (i.e. habitat) within an area is often used as an explanatory variable in species distribution models. However, it is possible that a simple binary presence/absence of the suitable habitat might be the most important determinant of the presence/absence of some species and, thus, be a better predictor of speci...

Aim The spectral variability hypothesis (SVH) suggests a link between spectral variation and plant biodiversity. The underlying assumptions are that higher spectral variation in canopy reflectance (depending on scale) is caused by either (1) variation in habitats or linked vegetation types or plant communities with their specific optical community...

In January 2019, Italy banned the sale of plastic cotton buds, which is one of the most abundant litter items entering the sea and then washing ashore. However, since the ban came into force, no studies have been carried out to assess whether the measure has actually led to the reduction of plastic cotton buds accumulating on Italian coasts. Here w...

The macro-site includes the following research sites along the Apennine mountain range: LTER_EU_IT_022 – Central and Southern Apennine: Majella-Matese LTER_EU_IT_025 – Central Apennine: Velino-Duchessa LTER_EU_IT_024 – Central Apennine: Gran Sasso LTER_EU_IT_023 – Northern Apennine It consists of “orographic islands” with high elevation vegetation...

Beyond the importance of ponds for aquatic and terrestrial life, pond networks seem to be crucial to providing a vital spatial resource in response to global climate change for all migrating and spreading taxa. Additionally, ponds offer sustainable solutions to issues of concern in water management, such as nutrient retention, rainfall interception...

Question Vegetation in the alpine and treeline ecotone faces changes in both climate and land use. Shrub encroachment is considered an effect of these changes, but it’s still unclear how this effect is mediated by environmental heterogeneity. Our goal is to determine which environmental factors shape the fine-scale spatial distribution and temporal...

Prompt estimation of phytoplankton biomass is critical in determining the ecological quality of freshwaters. Remote Sensing (RS) may provide new opportunities to integrate with situ traditional monitoring techniques. Nonetheless, wide regional and temporal variability in freshwater optical constituents makes it difficult to design universally appli...

Aims The link between spectral diversity and in-situ plant biodiversity is one promising approach for using remote sensing for biodiversity assessment. Nevertheless, there is little evidence to whether this link is maintained at fine scales, as well as to how it is influenced by vegetation’s vertical complexity. Here we test, at community level in...

Habitat monitoring in Europe is regulated by Article 17 of the Habitats Directive, which suggests the use of typical species to assess habitat conservation status. Yet, the Directive uses the term “typical” species but does not provide a definition, either for its use in reporting or for its use in impact assessments. To address the issue, an onlin...

The theory of island biogeography postulates that size and isolation are key drivers of biodiversity on islands. This theory has been applied not only to true (e.g. oceanic) islands but also to terrestrial island‐like systems (e.g. edaphic islands). Recently, a debate has opened as to whether terrestrial island‐like systems function like true islan...

Inland freshwaters are of great importance for human health and activities, but major stressors such as nutrient pollution, deforestation, and urbanization are compromising their status. Water quality degradation and freshwater ecosystem preservation are current issues worldwide requiring frequent and efficient monitoring protocols. The increasing...

Question Does spectral diversity captured by unmanned aerial systems (UAS) provide reliable information for monitoring the eco‐geomorphological integrity of Mediterranean coastal dune ecosystems? Can this information discriminate between two coastal areas with low (LP) and high (HP) human pressure? Location Tyrrhenian coast, Central Italy. Method...

In the light of unprecedented change in global biodiversity, real-time and accurate ecosystem and biodiversity assessments are becoming increasingly essential. Nevertheless, estimation of biodiversity using ecological field data can be difficult for several reasons. For instance, for very large areas, it is challenging to collect data that provide...

Aim The majority of work done to gather information on the Earth's biodiversity has been carried out using in‐situ data, with known issues related to epistemology (e.g., species determination and taxonomy), spatial uncertainty, logistics (time and costs), among others. An alternative way to gather information about spatial ecosystem variability is...

Abstract 1. Ecosystem heterogeneity has been widely recognized as a key ecological feature, influencing several ecological functions, since it is strictly related to several ecological functions like diversity patterns and change, metapopulation dynamics, population connectivity, or gene flow. 2. In this paper, we present a new R package - rasterd...

Ecosystem heterogeneity has been widely recognized as a key ecological feature, influencing several ecological functions, since it is strictly related to several ecological functions like diversity patterns and change, metapopulation dynamics, population connectivity, or gene flow. In this paper, we present a new R package - rasterdiv - to calculat...

Aim The majority of work done to gather information on Earth diversity has been carried out by in-situ data, with known issues related to epistemology (e.g., species determination and taxonomy), spatial uncertainty, logistics (time and costs), among others. An alternative way to gather information about spatial ecosystem variability is the use of s...

The majority of work done to gather information on Earth diversity has been carried out by in-situ data, with known issues e related to epistemology (e.g., species determination and taxonomy), spatial uncertainty, logistics (time and costs), among others. An alternative way to gather information about spatial ecosystem variability is the use of sat...

Aims Humans have deeply eroded biogeographic barriers, causing a rapid spread of alien species across biomes. The Mediterranean Basin is a biodiversity hotspot but is also known as a hub of alien plant invasions, particularly in its European part. Yet, a comprehensive inventory of alien species in the area is missing and understanding of the driver...

In the light of unprecedented change in global biodiversity, real-time and accurate ecosystem and biodiversity assessments are becoming increasingly essential. Nevertheless, estimation of biodiversity using ecological field data can be difficult for several reasons. For instance, for very large areas, it is challenging to collect data that provide...

Coastal dunes are found at the boundary between continents and seas representing unique transitional mosaics hosting highly dynamic habitats undergoing substantial seasonal changes. Here, we implemented a land cover classification approach specifically designed for coastal landscapes accounting for the within-year temporal variability of the main c...

Coastal erosion, in combination with sea-level rise and extreme meteorological events, is globally threatening the biodiversity and functioning of dune ecosystems, along with the essential ecosystem services they provide. In this study, by quantifying the intensity of erosion and accretion processes occurred over two decades in a wide Mediterranean...

In the Mediterranean sandy coasts, urban expansion mainly occurs to support seaside tourism, causing a drastic loss of natural coastal dune habitats and the associated ecosystem services. We investigated on a representative tract of the Mediterranean coast to which extent land conversion into urban areas affected natural dune ecosystems and the rel...

Species occurrences inherently include positional error. Such error can be problematic for species distribution models (SDMs), especially those based on fine‐resolution environmental data. It has been suggested that there could be a link between the influence of positional error and the width of the species ecological niche. Although positional err...

Terrain attributes (e.g., slope, rugosity) derived in Geographic Information Systems (GIS) from digital terrain models (DTMs) are widely used in both terrestrial and marine ecological studies due to their potential to act as surrogates of species distribution. However, the spatial resolution of DTMs is often altered to match the scale at which spec...

Coastal areas harbor the most threatened ecosystems on Earth, and cost-effective ways to monitor and protect them are urgently needed, but they represent a challenge for habitat mapping and multi-temporal observations. The availability of open access, remotely sensed data with increasing spatial and spectral resolution is promising in this context....

Invasive Alien Species (IAS) pose a major threat to biodiversity and ecosystem services worldwide. Even if preventing biological invasions should be the most cost-effective way to minimise the impact of IAS on biodiversity, new efforts are necessary to identify early signs of invasion and to assess invasion risk. In this context, the implementation...

In light of the global biodiversity loss, syntheses of the available knowledge about drivers of biodiversity are becoming increasingly important. However, despite the high number of studies analyzing patterns of plant species diversity, few attempts have been made to synthesize findings within different ecosystems. In this work, the relative role o...

A common feature of most theories of invasion ecology is that the extent and intensity of invasions is driven by a combination of drivers, which can be grouped into three main factors: propagule pressure (P), abiotic drivers (A) and biotic interactions (B). However, teasing apart the relative contribution of P, A and B on Invasive Alien Species (IA...

Reforestation after land abandonment across Mediterranean mountains, together with the related landscape pattern dynamics and its possible impacts on the natural flora and fauna are issues that need further research efforts. This research, based on multi-temporal land cover maps derived from remotely sensed data (1987, 2003, 2016) of the Central Ap...

Preventing biological invasions in areas of conservation concern represents the most cost-effective strategy to minimize the impact of Invasive Alien Species (IAS) on native communities. In this context, invasive Species Distribution Models (iSDMs) are a sound tool for predicting invasion risk in protected areas. Although their potential to support...

The IAVS Young Scientists are an official section of the International Association for Vegetation Science (IAVS) since October 2014, by now including more than 160 members. “Young Scientists” are loosely defined as those persons who are at an early stage in their career in Vegetation Science, regardless of age or enrolment status at a university. T...

In this explorative study we applied a set of uni- and bi-variate diversity metrics (α-diversity, Whittaker β-diversity, γ-diversity, Whittaker plot) to two sampled ‘communities’ of anthropogenic beach litter. Meso-litter represented the ‘species’ with the highest number of items. Comparing the two sampled sites, we observed different values in tot...

In this explorative study we applied a set of uni- and bi-variate diversity metrics (α-diversity, Whittaker β-diversity, γ-diversity, Whittaker plot) to two sampled ‘communities’ of anthropogenic beach litter. Meso-litter represented the ‘species’ with the highest number of items. Comparing the two sampled sites, we observed different values in to...

Aim Habitat fragmentation and loss are two of the most important factors driving current biodiversity decline. Nonetheless, the relationship between biodiversity and landscape patterns appears more complex than generally expected, depending on the species and communities involved. We aim to enrich knowledge concerning the relationship between plant...