Neighbor Effects Research Articles

Tactical conflict resolution in urban airspace for unmanned aerial vehicles operations using attention-based deep reinforcement learning

Unmanned aerial vehicles (UAVs) have gained much attention from academic and industrial areas due to the significant number of potential applications in urban airspace. A traffic management system for these UAVs is needed to manage this future traffic. Tactical conflict resolution for unmanned aerial systems (UASs) is an essential piece of the puzzle for the future UAS Traffic Management (UTM), especially in very low-level (VLL) urban airspace. Unlike conflict resolution in higher altitude airspace, the dense high-rise buildings are an essential source of potential conflict to be considered in VLL urban airspace. In this paper, we propose an attention-based deep reinforcement learning approach to solve the tactical conflict resolution problem. Specifically, we formulate this task as a sequential decision-making problem using Markov Decision Process (MDP). The double deep Q network (DDQN) framework is used as a learning framework for the host drone to learn to output conflict-free maneuvers at each time step. We use the attention mechanism to model the individual neighbor's effect on the host drone, endowing the learned conflict resolution policy to be adapted to an arbitrary number of neighboring drones. Lastly, we build a simulation environment with various scenarios covering different types of encounters to evaluate the proposed approach. The simulation results demonstrate that our proposed algorithm provides a reliable solution to minimize secondary conflict counts compared to learning and non-learning-based approaches under different traffic density scenarios.

Effects of tree density and herbaceous plants on tree seedling survival across the growing and non-growing season in a temperate forest

Tree seedling survival is critical for estimating forest recruitment, but it remain elusive about how neighboring tree’s density and herbaceous plants affect it. To assess the relative importance of tree density and herbaceous plants on tree seedling survival during the growing season and non-growing season, we established a two-year experiment with seedling census and removal of herbaceous plants in both secondary and old-growth temperate forest sites in the temperate forests of northeastern China. A total of 3,443 seedlings in 17 tree species were surveyed in this study. We found that both tree density and herbaceous plants significantly affected tree seedling survival, but the specific effects depended on shade tolerance, seedling growth stage and growing season. Conspecific adult neighbors had significant negative effects on the survival of shade-tolerant seedlings during the growing season, while conspecific seedling densities positively correlated with shade-intolerant seedlings. Herb removal significantly improved the survival of newly germinated and shade-intolerant seedlings during the growing season. Furthermore, we found that the survivals of both newly germinated and established seedlings differed seasonally in response to adult, seedling neighbors and herb removal. Herb removal enhances seedling survival during the non-growing season by offsetting the negative effects of conspecific adult neighbors during the growing season. Our findings provide new evidence for seedlings’ shade tolerance, growth stage and seasonal dependence of density dependence in temperate forests, and highlight the significance of herbaceous plants for seedling survival, an important factor that has been neglected in many previous studies.

Integrating local and neighboring area influences into vulnerability modeling of infectious diseases in Singapore

Infectious disease spreading is a spatial interaction process. Assessing community vulnerability to infectious diseases thus requires not only information on local demographic and built environmental conditions, but also insights into human activity interactions with neighboring areas that can lead to the transition of vulnerability from locations to locations. This study presented an analytical framework based on the Particle Swarm Optimization model to estimate the weights of the factors for vulnerability modeling, and a local proportional parameter for use in the integration of the local and neighboring area risks. A country model and five cross-region validation models were developed for the case study of Singapore to assess the vulnerability to COVID-19. The results showed that the identified weights for the factors were robust throughout the optimization process and across various models. The local proportional parameter could be set slightly higher in between 0.6 and 0.8 (out of 1), signifying that the local effect was higher than the neighboring effect. Computation of the weights from the optimal solutions for the integrated vulnerability index showed that the factors of human activity intensity and accessibility to amenities had much higher weights, at 0.5 and 0.3, respectively. Conversely, the weights of population density, elderly population, social economic status and land use diversity were much lower. These findings underscored the importance of considering non-equal weights for factors and incorporating spatial interactions between local and neighboring areas for vulnerability modeling, to provide to a more comprehensive assessment of vulnerability to infectious diseases.

Some new constructions of minimal efficient circular nearly strongly balanced neighbor designs

Neighbor designs are popular to control neighbor effects. Among neighbor designs, strongly balanced neighbor designs are important to estimate treatment effects and neighbor effects independently. Minimal circular strongly balanced neighbor designs (MCSBNDs) can be obtained only for odd v (number of treatments). For v even, minimal circular nearly strongly balanced neighbor designs are used which satisfied all conditions of MCSBNDs except that the treatment labeled as (v − 1) does not appear as its own neighbor. These designs can be converted directly in some other useful classes of neighbor designs. These designs are efficient to minimize the bias due to the neighbor effects.

Catalogues of Some Useful Classes of Circular Designs in Blocks of Three Different Sizes to Control Neighbor Effects

Minimal neighbor designs minimize the bias raised due to the neighbor effects using the minimum number of experimental units. Minimal circular balanced and strongly balanced neighbour designs can be constructed only for odd v (number of treatments to be compared). For v even, minimal Quasi Rees and nearly strongly balanced neighbor designs are constructed. In this article, the construction procedures of these four classes are described. Catalogues of these designs in blocks of three different sizes are also presented which provide the readymade solution to the experimenters and researchers.

The relative importance of drought stress and neighbor richness on plant–plant interactions shifts over a short time

Exploring how plant–plant interactions between species and their neighbors vary with biotic and abiotic factors is vital to understanding community assembly mechanisms in the context of global changes. In this study, using a dominant species (Leymus chinensis (Trin.) Tzvel.) in the semiarid Inner Mongolia steppe as the target species and ten other species as neighbors, we carried out a microcosm experiment to evaluate how drought stress, neighbor richness and season affected the relative neighbor effect (Cint) (the ability to reduce growth of target species). The factor of season interactively affected the effect of drought stress or neighbor richness on Cint. In the summer, drought stress decreased Cint directly and indirectly by decreasing SLA hierarchical distance and neighbor biomass. In the subsequent spring, drought stress increased Cint, and neighbor richness increased Cint directly and indirectly by increasing neighbor community functional dispersion (FDis) and neighbor biomass. Specifically, SLA hierarchical distance was positively associated with neighbor biomass, while height hierarchical distance was negatively associated with neighbor biomass in both seasons, which increased Cint. These findings show that the relative importance of drought stress and neighbor richness on Cint shifted over seasons, which provides strong empirical evidence of how plant–plant interactions respond to changes in biotic and abiotic factors in the semiarid Inner Mongolia steppe over a short-term time. Furthermore, this study provides novel insight into community assembly mechanisms in the context of climatic aridity and biodiversity loss in semiarid regions.

Accelerated Amidation of a Glycine Propargyl Ester on a Polymer and the Two-Way Use of One-Pot Double Postpolymerization Modification with Click Chemistry

Abstract The glycine propargyl (GP) ester moiety, as a newly activated ester, is a candidate for amidation in modification reactions and can be combined with click chemistry. Here, the amidation of GP esters on a polymer side chain was investigated using various amino-group-containing compounds. The amidation on the GP ester proceeded well when n-alkyl, cycloalkyl, and aromatic-group-containing primary amines were used without a catalyst under neutral conditions. Hydrophilic amines containing hydroxy and carboxy groups provided no amidation products. The amidation on the polymer was accelerated by the neighboring group effect on the polymer side chain. One-pot double postpolymerization modification was achieved using a GP ester-bearing polymer by combining amidation with the Huisgen cycloaddition.

Investigating above- vs. below-ground competition by accounting for azimuth of competitors in native eucalypt forests

Competition for both above-ground and below-ground resources plays a crucial role in shaping the structure and dynamics of plant communities. Above-ground competition for light may be more azimuthal and size-asymmetric than below-ground competition. However, there has been limited research on azimuthal effects in competition and development of related methods that may help distinguish between above- vs. below-ground competition. The aims of this study were to 1) develop novel approaches to evaluate the azimuthal effect of competition; 2) illustrate and evaluate these approaches by applying them to dominant eucalypt species in two mid-latitude Mediterranean climate forests; and 3) show how these methods can provide insights into the relative importance of above- vs. below-ground competition in these different species. We developed, applied and evaluated three new methods to evaluate azimuthal differences in competition, using models predicting DBH growth in two different forests (Eucalyptus marginata, jarrah and Corymbia callophyla, marri) and karri forest (E. diversicolor, karri; and Corymbia callophylla, marri) of south-west Western Australia. The foliage density of karri/marri is higher than that of jarrah, and the karri/marri site had higher rainfall. Both sites included thinned (thinning from below) and unthinned plots, regenerated naturally, and aged 100 year (jarrah) and 50 year (karri and marri). First, we compared the ability to predict growth using competitors in specific azimuths only vs. all competitors together. Second, we investigated whether weighting competitive effects of neighbours according to their azimuth could improve growth predictions. Third, we investigated whether growth prediction could be improved by accounting for relative size of competitors as well as their azimuth. We found evidence of an azimuthal effect of competition on growth in jarrah, karri and marri forest through all three new approaches. The third approach showed the existence of size-asymmetric competition. Improvement in model prediction was relatively small when accounting for the azimuth, which suggests that above-ground competition for light is low and most competition in jarrah, karri and marri forests is for below-ground resources. The three approaches developed and illustrated in this study can potentially help identify, distinguish and understand above- vs. below-ground competition for tree species in different parts of the world where competition among trees is one of the limiting factors of forest growth, dynamics and health.

The role of ecotypic variation for plant facilitation in a metal-polluted system: Stress-intolerant target ecotypes are the best beneficiaries and stress-tolerant nurse ecotypes the best benefactors

Disentangling competitive-response and -effect abilities has strongly improved our understanding of the role of competition for the diversity and composition of plant communities. Much less is known about the relative importance of facilitative-effect and -response abilities in harsh ecosystems. Here, we aim to fill this gap by simultaneously assessing the facilitative-response and -effect abilities of different species and ecotypes in former mining sites in the French Pyrenees, both in naturally occurring communities and in a common-garden designed on a slag heap. The response of two ecotypes of the target species Festuca rubra with contrasting metal-stress tolerances and the facilitative effects of two ecotypes with contrasting metal-stress tolerances of four different metallicolous nurse species were assessed. The results revealed that the response of the Festuca ecotype with lower metal-stress tolerance shifted from competitive (RII = −0.24) to facilitative (RII = 0.29) as pollution increased, consistently with the stress-gradient-hypothesis. The Festuca ecotype with high metal-stress tolerance did not show any facilitative response. Regarding facilitative effect ability assessed in the common-garden, nurse ecotypes from highly polluted habitats (RII = 0.04) had a significantly higher facilitative effects than ecotypes from less polluted habitats (RII = −0.05). Metal-intolerant target ecotypes of Festuca rubra were the most sensitive to the positive effects of neighbours, while metal-tolerant nurse ecotypes were the best benefactors. Facilitative-response ability appeared to be driven by a trade-off between stress-tolerance and facilitative response of target ecotypes. In contrast, facilitative-effect ability was positively correlated to the stress-tolerance of nurse plants. The results of this study show that the highest restoration success of highly metal-stressed systems should be found when highly stress-tolerant nurse ecotypes are associated with less stress-tolerant target ecotypes.

Ce6/PTX2-NP/G@NHs Confer Radiosensitivity in Non-Small Cell Lung Cancer via Promotion of Apoptotic Body-Mediated Neighboring Effects.

This study fabricates a nanoparticle delivery system of gold nanoparticles-dextran nanoparticles loaded with hypoxia-activated paclitaxel dimeric prodrug nanoparticles (PTX2-NP) and photosensitizer chlorin e6/paclitaxel-nanoparticle/gold@N-(2-hydroxypropyl) (Ce6/PTX2-NP/G@NHs) and analyzed the possible molecular mechanism for enhancing the radiosensitivity of non-small cell lung cancer (NSCLC). Ce6/PTX2-NP/G@NHs were prepared by a coupling reaction and dextran inclusion, followed by characterization using spectroscopy techniques. The cellular uptake and cytotoxicity of Ce6/PTX2-NP/G@NHs were analyzed. Radiosensitizing effects of the nanoparticles were evaluated by determining the malignant phenotypes and reactive oxygen species production of A549 cells and PI3K/AKT pathway-related proteins under 685 nm laser irradiation. A549 tumor-bearing nude mice were modeled to further confirm the radiosensitizing effect. Ce6/PTX2-NP/G@NHs were effectively internalized by A549 cells, producing cytotoxicity under laser irradiation. Ce6/PTX2-NP/G@NHs reduced cell viability, clonogenic potential, migration, and invasion along with reactive oxygen species (ROS) production while promoting apoptosis in A549 cells under laser irradiation. By inhibiting the PI3K/AKT pathway, Ce6/PTX2-NP/G@NHs increased the sensitivity of A549 cells to radiotherapy where apoptotic body (ApoBD)-mediated neighboring effects also played a key role. Ce6/PTX2-NP/G@NHs accumulated in tumor sites of nude mice and enhanced the radiosensitivity of NSCLC. Ce6/PTX2-NP/G@NHs showed no obvious toxicity or side effects in vivo. Collectively, the new Ce6/PTX2-NP/G@NHs nanoparticle delivery system can enhance the radiosensitivity of NSCLC via the promotion of ApoBD-mediated neighboring effects and inactivation of the PI3K/AKT pathway.

Firearm Legislation - The Association between Neighboring States and Crude Death Rates.

Few studies have examined the impact of interstate differences in firearm laws on state-level firearm mortality. We aim to study the association between neighboring states' firearm legislation and firearm-related crude death rate (CDR). The CDC Web-based Injury Statistics Query and Reporting System (WISQARS) was queried for adult all-intent (accidental, suicide, and homicide) firearm-related CDR among the 50 states from 2012 to 2020. States were divided into five cohorts based on the Giffords Law Center Annual Gun Law Scorecard and two groups were constructed: Strict (A, B, C) and Lenient (D, F). We examined the effect of 1) a single incongruent neighbor, defined as "Different" if the state is bordered by ≥1 state with a grade score difference > 1, and 2) the average grade of all neighboring states, defined as "Different" if the average of all neighboring states resulted in a grade score difference > 1. Strict states with similar average neighbors had significantly lower CDR compared to Strict states with different average neighbors (2.98 [1.91-5.06] vs. 3.87 [2.37-5.94], p = 0.02) while Lenient states with similar average neighbors had significantly higher CDR compared to Lenient states with different average neighbors (6.02 [4.56-8.11] vs. 4.7 [3.95-5.35], p = 0.002). Lenient states surrounded by all similar Lenient states had the highest CDR, which was significantly higher than Lenient states with ≥1 different neighbor (6.52 [5.09-8.96] vs. 5.19 [3.85-6.61], p < 0.001). However, Strict states with ≥1 different neighbor did not have higher CDR compared to Strict states surrounded by all similar Strict states (3.39 [2.17-5.35] vs. 3.14 [1.91-5.38], p = 0.5). We report a lopsided neighboring effect whereby Lenient states may benefit from at least 1 Strict neighbor while Strict states may be adversely affected only when surrounded by mostly Lenient neighbors. These findings may assist policymakers regarding the efficacy of their own state's legislation in the context of incongruent neighboring states. IV, retrospective observational.

Some important classes of non-directional minimal circular weakly balanced neighbor designs

Minimal neighbor designs are useful to balance out neighbor effects economically. The method of cyclic shifts provides the construction of these minimal designs in circular blocks only for v odd, where v is the number of treatments to be compared. Minimal circular weakly balanced neighbor designs are used for v even. In this article, two classes of minimal circular weakly balanced neighbor designs are constructed for v even. In class I, v/2 of all unordered pairs of two distinct treatments appear twice as neighbors while the remaining ones appear once. In class II, 3v/2 of all unordered pairs appear twice as neighbors.

Contrasting seed traits of co-existing seeds lead to a complex neighbor effect in a seed-rodent interaction.

Scatter-hoarding rodents play important roles in seed dispersal and predation in many forest ecosystems. Existing studies have shown that the seed foraging preference of rodents is directly affected by seed traits and indirectly affected by the traits of other co-existing seeds nearby (i.e., neighbor effect). Plant seeds exhibit a combination of diverse seed traits, including seed size, chemical defense, and nutrient content. Therefore, it is difficult to evaluate the influence of each single seed trait on such neighbor effects. Here, by using artificial seeds, we investigated the impacts of contrasts in seed size, tannin content, and nutrient content on neighbor effects. We tracked 9000 tagged artificial seeds from 30 seed-seed paired treatments in a subtropical forest in southwest China. The contrast in seed size between paired seeds created obvious neighbor effects measured through three seed dispersal related indicators: the proportion of seeds being removed, the proportion of seeds cached, and the distance transported by rodents. However, the magnitudes and the signs of the neighbor effects differed among pairs, including both apparent mutualism and apparent competition, depending on the contrast in seed size between paired seeds. The contrasts of tannin and nutrient content between paired seeds showed relatively few neighbor effects. Our results suggest that the contrast in seed traits between the target seed and its neighboring seeds should be considered when studying rodent-seed interactions. Furthermore, we expect that similar complex neighbor effects may also exist in other plant-animal interactions, such as pollination and herbivory.

Quantifying neighbour effects on tree growth: Are common ‘competition’ indices biased?

Abstract Interactions among neighbouring plants are key determinants of plant growth. To characterise the cumulative effect of all neighbours on the growth of a focal plant, neighbourhoods are often described by ‘competition’ indices. Common competition indices calculate the summed size of neighbour plants (focal‐independent index [FII]) whilst others include the summed ratio of the neighbour size relative to focal plant size (focal dependent). A frequently overlooked statistical artefact is that focal‐dependent indices (FDIs) may lead to biased estimates of neighbourhood effects on plant growth when growth is size dependent. Here, we conduct a literature search to determine the most common index types used to explain neighbour effects on tree growth. We then assess the ability of two common index types—focal dependent and focal independent—to correctly infer neighbourhood effects in (1) observations of tree growth in an experimental forest in south‐east Tasmania, Australia, and (2) an artificially created dataset where tree growth is unrelated to the neighbourhood. Both indices detected the competitive neighbourhood effect on tree growth observed in our own dataset but differed in their conclusion regarding neighbour effects in the simulated data. Despite the simulated dataset being generated so there was no relationship between tree growth and their neighbourhood, the FDI detected strong, competitive neighbourhood effects when intrinsic growth was incorrectly related to tree size. In contrast, when we considered the FII as the neighbourhood metric, we correctly did not detect any neighbourhood effects in the simulated data regardless of how size‐dependent growth was described. Synthesis. ‘Competition’ indices are a useful method to characterise the cumulative neighbourhood effect on plant growth; however, we demonstrate that indices which include the size of the focal plant in their calculation can be biased by an inherent relationship between tree growth and initial size. Whilst this bias typically overstates the strength of competition in determining focal tree growth, we show that it can be mitigated by correctly describing intrinsic growth. We discuss the limitations of both index types, provide recommendations for performing statistical modelling and outline how to check for accurate neighbour inference.

Indirect functional effects of neighbors on food web compartments could not overcome density-dependent limited growth of a grazing minnow

Ecosystems include diverse taxonomic and functional groups of animals with variable levels of niche overlap that can lead to direct and indirect interactions with positive or negative outcomes. Species feeding at low trophic positions might be sensitive to interactions with co-occurring functional groups (neighbors) that influence their food resources through various processes, such as indirect nutrient subsidies and trophic cascades. Employing a target-neighbor experimental design using large, outdoor mesocosms, we tested whether adding neighbors with different functional traits affected food web compartments relative to a control group that had grazing minnows, Campostoma anomalum (Central Stoneroller). Additionally, we tested whether growth and body condition of Central Stoneroller was positively influenced through interactions with each neighbor treatment: additional stonerollers, benthic-insectivorous fish Etheostoma spectabile (Orangethroat Darter), terrestrial insectivorous fish Lepomis megalotis (Longear Sunfish), or filter-feeding mussels (two-species assemblage) that are predicted to increase primary production through nutrient enrichment, a trophic cascade or both. Over the 29-day experiment, the presence of neighbors had generally negative or highly variable effects on food web compartments. Stoneroller growth was not evident during the experiment and body condition generally declined but was not influenced by neighbor treatments. Our results show that adding neighboring functional group did not reduce density-dependent growth of grazing fishes via indirect food web interactions over short temporal scales. This study suggested that indirect interactions among species and their combined influence on ecosystem properties were weak under experimental conditions representing typical prairie stream communities.

Substitution or complementary effects between hosts and neighbors’ information disclosure: Evidence from Airbnb

Prior studies have attributed and confirmed the importance of hosts’ information disclosure on boosting their performance due to the prominent information asymmetry on peer-to-peer rental platforms. This study takes a step further by analyzing how hosts and neighbors’ disclosure of descriptions simultaneously and interactively influences the review volume and performance of Airbnb listings. Based on a panel dataset and fixed effect regression models, the results confirmed the findings of prior studies that self-disclosure of descriptions has a positive effect on the review volume and performance. We also initially find a substitute effect between self-disclosure of descriptions and neighbors’ disclosure of public information, with a complementary effect between self-disclosure of descriptions and neighbors’ disclosure of private information. As a novel attempt to analyze the effect of neighbors’ information disclosure on property performance, this study provides important implications for relevant literature and for hospitality professionals to improve information disclosure strategies.

Experimental evidence for nasty neighbour effect in western black crested gibbons (Nomascus concolor)

Experimental evidence for nasty neighbour effect in western black crested gibbons (Nomascus concolor)

Pathways to global-change effects on biodiversity: new opportunities for dynamically forecasting demography and species interactions.

In structured populations, persistence under environmental change may be particularly threatened when abiotic factors simultaneously negatively affect survival and reproduction of several life cycle stages, as opposed to a single stage. Such effects can then be exacerbated when species interactions generate reciprocal feedbacks between the demographic rates of the different species. Despite the importance of such demographic feedbacks, forecasts that account for them are limited as individual-based data on interacting species are perceived to be essential for such mechanistic forecasting-but are rarely available. Here, we first review the current shortcomings in assessing demographic feedbacks in population and community dynamics. We then present an overview of advances in statistical tools that provide an opportunity to leverage population-level data on abundances of multiple species to infer stage-specific demography. Lastly, we showcase a state-of-the-art Bayesian method to infer and project stage-specific survival and reproduction for several interacting species in a Mediterranean shrub community. This case study shows that climate change threatens populations most strongly by changing the interaction effects of conspecific and heterospecific neighbours on both juvenile and adult survival. Thus, the repurposing of multi-species abundance data for mechanistic forecasting can substantially improve our understanding of emerging threats on biodiversity.

Electrochemical Impedance Spectroscopy (EIS) Explanation of Single Crystal Cu(100)/Cu(111) in Different Corrosion Stages.

Copper and its alloys are used widely in marine environments, and anisotropic corrosion influences the corrosion kinetics of copper. Corrosion of copper in an electrolyte containing Cl- is described as a dissolution-deposition process, which is a prolonged process. Therefore, it is laborious to clarify the corrosion anisotropy in different stages. In this paper, electrochemical impedance spectroscopy (EIS) following elapsed open circuit potential (OCP) test with 0 h (0H), 24 h (24H) and 10 days (10D) was adopted. To exclude interruptions such as grain boundary and neighbor effect, single crystal (SC) Cu(100) and Cu(111) were employed. After 10D OCP, cross-sectional slices were cut and picked up by a focused ion beam (FIB). The results showed that the deposited oxide was Cu2O and Cu(100)/Cu(111) experienced different corrosion behaviors. In general, Cu(100) showed more excellent corrosion resistance. Combined with equivalent electrical circuit (EEC) diagrams, the corrosion mechanism of Cu(100)/Cu(111) in different stages was proposed. In the initial stage, a smaller capacitive loop of Cu(111) suggested preferential adsorption of Cl- on air-formed oxide film on Cu(111). Deposited oxide and exposed bare metals also played an important role in corrosion resistance. Rectangle indentations and pyramidal structures formed on Cu(100)/Cu(111), respectively. Finally, a perfect interface on Cu(100) explained the tremendous capacitive loop and higher impedance (14,274 Ω·cm2). Moreover, defects in the oxides on Cu(111) provided channels for the penetration of electrolyte, leading to a lower impedance (9423 Ω·cm2) after 10D corrosion.

The Role of Gorse (Ulex parviflorus Pourr. Scrubs) in a Mediterranean Shrubland Undergoing Climate Change: Approach by Hyperspectral Measurements

The goal of this study was to observe the neighbor effect of Gorse, a plant of the Fabaceae family, on three typical species of Mediterranean shrubland: kermes oak, white Cistus and rosemary. For this purpose, a hyperspectral analysis and the application of vegetation indices (VIs) were carried out. We provide the spectral signature of Gorse, which differs mainly from that of its companion species in the band between 700 and 1350 nm. This supposed Gorse effect was tested in natural conditions and in conditions of forced drought to simulate the effects of the climate change predicted for the Mediterranean Basin. Field spectrometry demonstrated the existence of such interactions between the four species. In control stands, the presence of Gorse significantly modifies the spectral responses of kermes, white Cistus and rosemary, mainly in the near-infrared region (700-1350 nm). Both tri- and tetra-specific plant assemblages also exhibited spectral changes, suggesting an indirect effect of Gorse. Under drought conditions, one-way ANOVA followed by Fisher's LSD test led us to identify the features involved in plants' coexistence with Gorse. The Cistus albidus reflectance spectrum was clearly increased in the presence of Gorse in rain-exclusion conditions. The application of several VIs allowed us to extract new information on the variation of spectral signatures. Unexpectedly, nitrogen supply by Gorse was not shown, except for Cistus, as shown by the VI NDVI (N) analysis. However, this study proved that Gorse can modify the behavior of its companion species in controls, but also in drought conditions, by increasing their photosynthesis activity (NIRvP) and water content (ratio R975/R900). Gorse therefore appears as a key species in the ecosystem of the Mediterranean shrubland, but its high vulnerability to drought leaves a vacant ecological niche in plant communities. While the spectral reflectance increases linearly with the specific richness in the lack of any disturbance, by contrast, climate aridification imposes a double reciprocal profile. This clearly means that multispecific plant communities cope better with climate change. Nevertheless, knowledge of the underlying mechanisms requires further structural, chemical, and biochemical investigation.