Undisturbed Sites Research Articles

Strong host-specific selection and over-dominance characterize arbuscular mycorrhizal fungal root colonizers of coastal sand dune plants of the Mediterranean region.

Sand dunes of the Mediterranean region constitute drought-stressed, low-fertility ecosystems. Arbuscular mycorrhizal fungi (AMF) are regarded as key components of their biota, that contribute to plant host adaptation and fitness. However, AMF community assembly rules in the roots of the psammophilous plants of coastal sand dunes have not been investigated. We studied the root colonizing AMF communities of four characteristic native plants of eastern Mediterranean coastal foredunes, in nine locations in Greece. Host-specificity (plant identity) was the major driver of AMF community assembly in the plant roots, while geographical distance between locations was not related to differences in the AMF communities. Additionally, colonizer AMF communities were characterized by over-dominance of a single operational taxanomic unit (OTUs), which was remarkably host-specific among locations. Wider dissimilarity in AMF communities was observed in small and disturbed (SD) sites compared to large and undisturbed (LU) sites, a trait that may be attributed to relaxed environmental filtering and facilitated AMF dispersal/immigration in SD sites from surrounding habitats. Overall, our results indicate that the assembly of root-colonizing AMF communities in the eastern Mediterranean sand dunes is characterized by strong biotic filtering (host identity), suggesting that co-adaptation processes may be more pronounced than previously proposed, under extreme environmental conditions.

Illegal harvesting threatens fruit production and seedling recruitment of Balanites aegyptiaca in Dinder Biosphere Reserve, Sudan

Illegal harvesting negatively affects the forest tree populations, particularly in sub-Saharan Africa, but little is known how fruit production and seedling recruitment are impacted. We assessed recruitment parameters of Balanites aegyptiaca trees in the Dinder Biosphere Reserve (DBR) across 100 sample plots of 25 m x 40 m in both human-impacted (disturbed) and undisturbed sites. We found that the average number of fruiting branches of B. aegyptiaca in the undisturbed sites were three times as high as those in the disturbed sites (F1,98 = 139, P < 0.001). Further, fruiting branches were positively correlated with crown width (R2 = 0.71, β = 7.1, P = 0.01) across both sites. The height and crown width of B. aegyptiaca in the undisturbed sites were double that of the disturbed sites (F1,196 = 80, P < 0.001; F1,196 = 94.8, P < 0.001). Saplings and seedlings at the undisturbed sites were three times and twice that of the disturbed sites, respectively (F1,196 = 94.5, P < 0.001; F1,196 = 100.8, P < 0.001), with a positive correlation to the average number of fruiting branches (R2 = 0.74, β = 0.45, P < 0.001). The soil nitrogen and phosphorus contents beneath trees in the undisturbed sites were almost double that of those in the disturbed sites (F1, 196 = 68.1, P < 0.001; F1, 196 = 97.9, P < 0.001) while sodium and electrical conductivity were by about 50% lower (F1, 196 = 535.8, P < 0.001; F1, 196 = 16.1, P < 0.001). We conclude that illegal harvesting in DBR severely reduced tree structure and recruitment parameters of B. aegyptiaca, which might also have impacted soil fertility. We urge for intensive monitoring and awareness-raising programs to conserve this vulnerable tree species.

Forest Structure and Projections of Avicennia germinans (L.) L. at Three Levels of Perturbation in a Southwestern Gulf of Mexico Mangrove

Mangrove forests have declined worldwide and understanding the key drivers of regeneration at different perturbation levels can help manage and preserve these critical ecosystems. For example, the Ramsar site # 1602, located at the Tampamachoco lagoon, Veracruz, México, consists of a dense forest of medium-sized trees composed of three mangrove species. Due to several human activities, including the construction of a power plant around the 1990s, an area of approximately 2.3 km2 has suffered differential levels of perturbation: complete mortality, partial tree loss (divided into two sections: main and isolated patch), and apparently undisturbed sites. The number and size of trees, from seedlings to adults, were measured using transects and quadrats. With a matrix of the abundance of trees by size categories and species, an ordination (nMDS) showed three distinct groups corresponding to the degree of perturbation. Projection matrices based on the size structure of Avicennia germinans showed transition probabilities that varied according to perturbation levels. Lambda showed growing populations except on the zone that showed partial tree loss; a relatively high abundance of seedlings is not enough to ensure stable mangrove dynamics or start regeneration; and the survival of young trees and adult trees showed high sensitivity.

Exploring the plant environmental DNA diversity in soil from two sites on Deception Island (Antarctica, South Shetland Islands) using metabarcoding

AbstractThe few Antarctic studies to date to have applied metabarcoding in Antarctica have primarily focused on microorganisms. In this study, for the first time, we apply high-throughput sequencing of environmental DNA to investigate the diversity of Embryophyta (Viridiplantae) DNA present in soil samples from two contrasting locations on Deception Island. The first was a relatively undisturbed site within an Antarctic Specially Protected Area at Crater Lake, and the second was a heavily human-impacted site in Whalers Bay. In samples obtained at Crater Lake, 84% of DNA reads represented fungi, 14% represented Chlorophyta and 2% represented Streptophyta, while at Whalers Bay, 79% of reads represented fungi, 20% represented Chlorophyta and &lt; 1% represented Streptophyta, with ~1% of reads being unassigned. Among the Embryophyta we found 16 plant operational taxonomic units from three Divisions, including one Marchantiophyta, eight Bryophyta and seven Magnoliophyta. Sequences of six taxa were detected at both sampling sites, eight only at Whalers Bay and two only at Crater Lake. All of the Magnoliophyta sequences (flowering plants) represent species that are exotic to Antarctica, with most being plausibly linked to human food sources originating from local national research operator and tourism facilities.

Oribatid (Acari: Oribatida) diversity in natural and altered open arid ecosystems of South-Eastern Caucasus

Oribatid mite diversity was investigated in the most understudied region of Georgian South-Eastern Caucasus – open arid ecosystems, which are under heavy natural and anthropogenic disturbance. Field sampling was performed in three geographical units and in each unit three types of ecosystems with different disturbance classes were studied: (1) Arable lands with severe (ASE) and moderate (AME) erosion; (2) Pastures with heavy (PH) and moderate (PM) overgrazing; (3) Natural grassland with severe (NSE), medium (NME) and no (N) erosion. Eighty species of oribatid mites were identified in total. Total raw richness of species was highest in natural grassland (68 species), followed by arable lands with medium erosion (50 species), natural grassland with medium erosion (44 species), pastures with medium erosion (41 species), overgrazed pastures (36 species), arable lands with severe erosion (35) and grassland with severe erosion (31 species). Non-parametric estimation of species richness showed 80 % of per-site sampling completeness on average. Similar to species richness, average individual density was also highest in natural sites (5500 in./m2) and lowest – in grassland with severe erosion (500 in./m2). Indicator Species Analyses (ISA) and regression analyses showed that the natural undisturbed sites displayed largest number of potential indicator species most of which are absent from disturbed sites. Natural grasslands are characterized by on average seven species (Ceratoppia quadridentata (Haller, 1882), Eremulus flagellifer Berlese, 1908, Oribatella berlesei (Michael, 1898), Oribatula interrupta (Willmann, 1939), Xenillus tegeocranus (Hermann, 1804), Metabelba papillipes (Nicolet, 1855), Striatoppia weigmanni Murvanidze & Behan-Pelletier, 2011) with high indicator value (i.e. specificity >0.9) irrespective the sampling season. No other oribatid species were found to be good indicators of other disturbance classes.

Algae on coral rocky reefs as indicators of disturbances along the Ecuadorian coast

We present an analysis of algal communities of two coral rocky reefs of the Ecuadorian coast. This study aims to determine which algae classify best two sites with different degrees of disturbance, considering the spatio-temporal variation of algal groups (macroalgae and turf) using a random forest approach. 14 algae species were recorded, eight belong to Rhodophyta, five to Chlorophyta and four to Phaeophyta. Overall macroalgae coverage species displayed significant differences between sites, among months and the interaction Site*Month. Based on a random forest classification algorithm, we performed a systematic study of the interactions using the algal coverage values. Our data indicated that coral rocky reefs disturbance in these sites of the Ecuadorian coast can be classified by the interactions of Dictyota dichotoma, Lobophora variegata and algal turf. Results of this study indicated that lower diversity of macroalgae were associated with higher macroalgae coverage of L. variegata and the presence of turf algae in the disturbed site. The presence of D. dichotoma and lower coverage of turf was associated with the undisturbed site. Our results evidence the interaction among algal turf and macroalgae on coral rocky reefs and exhibits them as indicators of disturbances along the coral rocky reef systems. Results from random forest analysis revealed that, with presence of Dictyota dichotoma, turf can function as a healthy alternate state at undisturbed sites.

Incidence of Pfas in soil following long-term application of class B biosolids

This field study investigated the impact of long-term land application of biosolids on PFAS presence in soils that received annual repetitive land application of Class B biosolids from 1984 to 2019. Soil samples were collected from three depths of 30.5, 91 and 183 cm below land surface. Biosolid and groundwater samples used for irrigation were also collected. Concentrations measured for 18 PFAS compounds were evaluated to assess incidence rates and potential impact on groundwater. No PFAS analytes were detected at the three sampling depths for soil samples collected from undisturbed sites with no history of agriculture, irrigation, or biosolids application (background control sites). Relatively low mean concentrations of PFAS ranging from non-detect to 1.9 μg/kg were measured in soil samples collected from sites that were used for agriculture and that received irrigation with groundwater, but never received biosolids. PFAS concentrations in soils amended with biosolids were similarly low, ranging from non-detect to a mean concentration of 4.1 μg/kg. PFOS was observed at the highest concentrations, followed by PFOA for all locations. PFAS detected in the irrigation water were also present in the soil. These results indicate that biosolids and irrigation water are both important sources of PFAS present in the soils for all of the study sites. Not all PFAS detected in the biosolids were detected in the soil. Very long chain PFAS present in the biosolids were not detected or were detected at very low levels for soil, suggesting potential preferential retention within the biosolids. The precursor NMeFOSAA was present at the second highest concentrations in the biosolids but not detected in soil, indicating possible occurrence of transformation reactions. The total PFAS soil concentrations exhibited significant attenuation with depth, with a mean attenuation of 73% at the 183 cm depth. Monotonically decreasing concentrations with depth were observed for the longer-chain PFAS.

Vegetation succession and soil cover transformation after extreme flood: A case study from the Sázava river floodplain

The goal of this study was to assess impact of flood on soil and vegetation cover in the Sazava river floodplain after an extreme spring flood in 2006. The impact on soil cover resulted mainly in vast erosion and sedimentation leading to differentiation of three fluvisol subtypes according to sediment coarseness. The impact on vegetation resulted in regeneration of herbaceous alluvial vegetation buried under a thin layer of sediments, succession of vegetation on eroded sites and succession of vegetation on new sediments. The regeneration of alluvial vegetation, expressed by vegetation cover, reached the same level as vegetation on undisturbed sites after 8 months. The succession of vegetation on new sites, studied within 25 m2 sampling plots and tested by using multivariate statistical methods, was primarily dependent on diaspores left on sites by the flood and on site type as well. The vegetation cover reached 100 percent at the end of the first vegetation season in both cases. There was a significant difference in species’ composition between eroded sites and sites on thick layers of sediments each year as hypothesized. There was also significant difference in vegetation succession between site types. <b>Sukcese vegetace a přeměna pokryvnosti půdy po extrémních záplavách. Případová studie v nivě Sázavy</b> Vliv extrémních záplav na vegetaci a půdní kryt byl studován v nivě Sázavy po jarní povodni v roce 2006. V prostoru nivy mezi Čerčany a Poříčím nad Sázavou došlo k rozsáhlé erozi a sedimentaci. Sledována byla jednak obnova aluviální vegetace pohřbené pod málo mocné vrstvy sedimentu, jednak sukcese vegetace na erozních plochách a mocných sedimentech. Regenerace aluviální vegetace byla rychlá. Pokryvnost vegetace disturbovaných ploch dosáhla po 8 měsících stejné pokryvnosti jako na plochách nedisturbovaných. Oproti předpokladu nebyla prokázána rozdílná rychlost zarůstání studovaných ploch (regenerující vegetace aluviálních luk, sukcese na erozních plochách a sukcese na sedimentech). Druhové složení vegetace na sukcesních plochách však bylo průkazně závislé na typu plochy. Druhové složení také průkazně závisí na typu plochy a sukcesním stáří.

Persistent effects of sand extraction on habitats and associated benthic communities in the German Bight

Abstract. Sea-level rise demands for protection measures of endangered coastlines crucial for the local population. At the island of Sylt in the SE North Sea, shoreline erosion is compensated by replenishment with sand dredged from an offshore extraction site. We studied the long-term effects of sand extraction on bathymetry, geomorphology, habitats and benthic fauna. Sand extraction created dredging holes about 1 km in diameter and up to 20 m below the ambient seafloor level. Directly after dredging the superficial sediment layer, inside the pits was dominated by coarse sand and stones. Hydroacoustic surveys revealed only minor changes of bathymetry &gt; 35 years after sand extraction. Obviously, backfill of the dredging pits was very slow, at a rate of a few millimeters per year, presumably resulting from low ambient sediment availability and relatively calm hydrodynamic conditions despite high wave energy during storms. Thus, a complete backfill of the deep extraction sites is likely to take centuries in this area. Hydroacoustic surveys and ground truthing showed that the backfilled material is mainly very fine sand and mud, turning the previously coarse sand surface into a muddy habitat. Accordingly, grab samples revealed significant differences in macrozoobenthos community composition, abundance and species density between recently dredged areas (&lt; 10 years ago), recovery sites (dredging activity &gt; 10 years ago) and undisturbed sites (control sites). Overall, dredging turned the original association of sand-dwelling species into a muddy sediment association. Since re-establishment of disturbed benthic communities depends on previous re-establishment of habitat characteristics, the low sedimentation rates indicate that a return to a pre-dredging habitat type with its former benthic community and habitat characteristics is unlikely. Since coarse sand is virtually immobile in this area, a regeneration towards pre-dredging conditions is also unlikely without human interference (e.g., mitigation measures like depositing coarse material on the seafloor to restore the sessile epifauna).

Shifting macroecological patterns and static theory failure in a stressed alpine plant community

AbstractAccumulating evidence suggests that ecological communities undergoing change in response to either anthropogenic or natural disturbances exhibit macroecological patterns that differ from those observed in similar types of communities in relatively undisturbed sites. In contrast to such cross‐site comparisons, however, there are few empirical studies of shifts over time in the shapes of macroecological patterns. Here, we provide a dramatic example of a plant community in which the species–area relationship and the species‐abundance distribution change markedly over a period of six years. These patterns increasingly deviate from the predictions of the maximum entropy theory of ecology (METE), which successfully predicts macroecological patterns in relatively static systems. The error in the species–area relationship prediction additionally correlates over time with increased stress measured as mortality minus recruitment, providing a link between demography and the failure of macroecological theory. Information on the dynamic state of an ecosystem inferred from snapshot measurements of macroecological community structure can potentially assist in identifying causes and consequences of disturbance and extending the domain of current theories and models to disturbed ecosystems.

Canopy Disturbances Catalyse Tree Species Shifts in Swiss Forests

Widely observed inertia of forest communities contrasts with climate change projections that suggest dramatic alterations of forest composition for the coming decades. Disturbances might be a key process to catalyse changes in tree species composition under environmental change by creating opportunities for ‘new’ species to establish. To test this assumption, we compared two assessments (1993–1995, 2009–2017) from the Swiss National Forest Inventory to evaluate which forests were opened by natural canopy disturbance (that is, wind, insect outbreaks, fire and drought) and if these disturbances altered tree species composition both in terms of species-specific basal area and recruitment densities. Natural disturbances affected 14% of the Swiss forests within 25 years, with wind and insect outbreaks being the most frequent (75%) and fire and drought being rare (< 1.5%). Disturbances led to a shift from conifer to broadleaf tree species at low elevation, in particular in dense Picea abies stands, but no change was observed at higher elevations. The composition of undisturbed sites persisted during the same period. Our results demonstrate that undisturbed forests widely resist changes in tree species composition as an effect of direct ingrowth by stand-forming species. Disturbance events seem necessary to create opportunities for climatically ‘better suited and site-adapted’ species to (re-)establish and therefore potentially catalyse tree species turnover under environmental changes. We detected a reduction of tree species that were—centuries ago—cultivated outside their primary natural range, in particular P. abies, or depended on traditional management practices (Pinus sylvestris, Castanea sativa), which may inform us on how the projected increase in disturbance frequency and severity might filter tree species composition and hereby alter forest structure.

Modeling riparian species occurrence from historical surveys to guide restoration planning in northwestern USA

AbstractSuccessful restoration of riparian habitats and functions depends in part on selection of plant species that are suited to local geomorphic and climatic conditions, which often relies on contemporary reference sites to characterize target riparian vegetation communities. In heavily modified landscapes, a lack of undisturbed sites hinders the description of reference conditions to help guide planning efforts. In lieu of contemporary reference sites, we used historical Public Land Survey data from the late 1800s and early 1900s to document historical streamside vegetation at 1685 sites distributed throughout the Columbia River basin. We used those data to construct a random forest classification model using climatic and geomorphic variables to predict the probability of occurrence of riparian vegetation groups (conifer, deciduous, shrub, and willow) and individual taxa (fir, pine, cedar, cottonwood, alder, sagebrush) for all stream reaches with bankfull width &gt;6 m in the interior Columbia River basin. The most common predictor variables included in the best models for vegetation groups or individual taxa were mean annual precipitation, minimum temperature, elevation, and bankfull width. For some taxa, temperature range and floodplain width were also important predictors. The probability maps indicate that riparian zones were likely dominated by willow species in semi‐desert regions and by conifer species in the humid mountain regions. Deciduous species dominated riparian areas in transition zones between conifer forests and semi‐deserts. Species distributions suggest that streams in the semi‐deserts were likely characterized by little shade and low wood abundance, whereas streams in the humid mountains would have been more heavily shaded with high wood abundance. The transitional deciduous areas were likely shaded with moderate wood abundance. Historical trends in air temperature and precipitation suggest relatively small changes in climate since the time of the surveys, indicating that current species ranges are likely similar to historical species ranges. Hence, these maps can be used to help identify suitable taxonomic groups and expected riparian functions for riparian restoration in the Columbia River basin, with appropriate adjustments made to site‐specific restoration designs to account for model uncertainty, future climate change, or land use constraints.

Spatial variability in water quality and macroinvertebrate assemblages across a disturbance gradient in the Mara River Basin, Kenya

Across the Afrotropical ecosystems human activities are increasingly modifying natural flow regimes, nutrient and organic matter loading and processing in streams and rivers with implications on ecosystem structure and functioning. The Mara River Basin has undergone extensive land-use change, but influences of these changes on water quality and aquatic communities are not well understood. This study investigated changes in water quality and macroinvertebrate assemblages across a disturbance gradient arising from rural human activities in nineteen sites; grouped into three condition categories (reference undisturbed (n = 7), moderately disturbed (n = 6) and disturbed (n = 6)). Temperature, dissolved oxygen, total dissolved solids, pH and electrical conductivity were measured in situ at each sampling site, and samples collected for analysis of nutrients and total suspended solids. Sampled macroinvertebrates were identified mainly to family level for analysis of structural and functional composition. There were significant spatial variations in water quality variables across the disturbance gradient (p <0.05). Highest mean temperature and suspended solids were recorded at the disturbed sites and lowest at undisturbed sites. Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa dominated (70% in abundance) undisturbed sites while Diptera dominated (48% in abundance) at disturbed sites. Additionally, higher diversity and richness indices were recorded at undisturbed sites. Collectors were the dominant taxa at all sites with the abundance of shredders being highest at undisturbed sites. This study adds further evidence showing that land-use change from forestry to agriculture has a strong influence on the structural and functional composition of macroinvertebrates in Afrotropical streams.

Phytophthora species repeatedly introduced in Northern California through restoration projects can spread into adjacent sites

This study investigates whether Phytophthora species may have been repeatedly introduced in natural habitats through restoration projects. Six plant species across five research locations in three counties within the San Francisco Bay Area were tested for pathogen infection of stems, roots and for rhizosphere infestation at failing restoration sites. Where possible, the same hosts were evaluated in one neighboring un-restored site disturbed by the presence of culverts, drainages or trails that also intersected the restoration site, and in a naturally regenerated and undisturbed control site. Although native or endemic pathogens were isolated from all three types of sites, Phytophthora species were never isolated from control undisturbed sites. Statistical analyses confirmed that percentage of positive Phytophthora isolations was significantly higher in restoration sites and adjoining disturbed sites than in control sites. Presence of Phytophthora species was correlated with disease symptoms, plant death and lack of regeneration. Furthermore, six of eight Phytophthora species isolated in the field had previously been reported from plant production facilities providing stock for habitat restoration. To our knowledge, this is the first controlled survey linking the presence of entire Phytophthora species assemblages to failing restoration projects and to the plant production facilities that provide plant stock for restoration, while showing that Phytophthora species are absent in neighboring undisturbed sites. This study further proves that these pathogens are spreading from restoration sites through disturbance pathways.

Local and global trace plutonium contributions in fast breeder legacy soils

Trace-level plutonium in the environment often comprises local and global contributions, and is usually anthropogenic in origin. Here, we report estimates of local and global contributions to trace-level plutonium in soil from a former, fast-breeder reactor site. The measured 240Pu/239Pu ratio is anomalously low, as per the reduced 240Pu yield expected in plutonium bred with fast neutrons. Anomalies in plutonium concentration and isotopic ratio suggest forensic insight into specific activities on site, such as clean-up or structural change. Local and global 239Pu contributions on-site are estimated at (34 ± 1)% and (66 ± 3)%, respectively, with mass concentrations of (183 ± 6) fg g−1 and (362 ± 13) fg g−1. The latter is consistent with levels at undisturbed and distant sites, (384 ± 44) fg g−1, where no local contribution is expected. The 240Pu/239Pu ratio for site-derived material is estimated at 0.05 ± 0.04. Our study demonstrates the multi-faceted potential of trace plutonium assay to inform clean-up strategies of fast breeder legacies.

Community changes in odonate monitoring: why are long‐term studies so relevant?

Abstract Most ecological studies involving insects are based on medium‐ and short‐term observations; however, the extent to which such data captures reality remains unclear. We investigated the long‐term dynamics of two Odonata communities (disturbed and undisturbed sites) over 18 years and analysed the differences in the short‐ and long‐term results. We also focused on the sampling methodology to enhance the efficacy and objectivity of long‐term monitoring involving Odonata. During one year, we captured only 53% of the overall species richness; during three consecutive sampling years, it was 65%. To capture 95%, we needed 16 years. Changes in quantitative similarity (Renkonen index, P) were more pronounced within sites over time than between sites. Species constancy significantly increased with the maximum abundance class but decreased with increasing fluctuation ratio and specialisation (Dragonfly Biotic Index). Based on exuviae, we detected half of the species compared to adults, but the species accumulation curves peaked after a few sampling years. Long‐ and short‐term monitoring yield different results, both qualitatively (species richness, specialisation) and quantitatively (abundance, dominance). Ideal sampling should be sequential, lasting at least 10 years (capturing &gt;80% of species). Intermittent sampling (one‐year interspersed with pauses), allowing the inclusion of multiple sites in monitoring programme, may also provide satisfactory results when performed over a longer period. Over the long term, sampling adults semi‐quantitatively and exuviae qualitatively provided sufficient information, while being feasible in terms of both personnel and costs, thereby overcoming the main pitfalls of long‐term monitoring programmes.

Effects of fragmented mangroves on macrozoobenthos: a case study of mangrove clearance for powerline right-of-way at Oproama Creek, Niger Delta, Nigeria

Mangroves are vulnerable to varying magnitudes of degrading impact by human activities. Despite the many benefits of mangrove ecosystems, mangroves in the Niger Delta region are often cleared for electric powerline and oil pipeline rights-of-way, recreation, road construction, housing and farming. The study assessed the impacts of mangrove clearance on physico-chemical parameters of interstitial water and macrozoobenthic primary community structure in Oproama Creek, Nigeria, from February to July 2016. Three stations were selected for the study: two stations in more natural and undisturbed mangroves and one station at a mangrove clearing (for a national grid powerline right-of-way). Species richness and diversity were slightly higher at the undisturbed mangrove sites than the cleared site. Removal of mangrove canopy shade alters microclimate temperature regime and other temperature-dependent parameters, imposing thermal stress on stenothermal taxa and ancillary stressors that compositely affected primary community structure indices. Deliberate loss of mangroves through clearing waterfront vegetation as a driver for improved visual monitoring and enhanced security in the Oproama Community in the Niger Delta is reported for the first time. The wider implications of mangrove clearance and fragmentation on ecosystem-based goods and services are discussed. Limiting mangrove spatial loss owing to construction of an electric tower cutline within coastal landscape is strongly recommended.

Domestic Dogs and Wild Foxes Interactions in a Wildlife-Domestic Interface of North-Central Chile: Implications for Multi-Host Pathogen Transmission.

Domestic dogs (Canis familiaris) often cohabite at interfaces shared by humans and wildlife, interacting with wild canids as predators, prey, competitors and reservoirs of several multi-host pathogens, such as canid-borne micro and macro parasites that could impact on wildlife, livestock and public health. However, spatio-temporal patterns of indirect interactions as promoters of pathogen transfer between domestic and wild canids are largely unknown. In this study, we used camera traps to describe the activity patterns and habitat use of dogs, chilla (Lycalopex griseus) and culpeo (Lycalopex culpaeus) foxes and identify the local-scale factors that may affect the frequency of dog-fox interactions through an anthropization gradient of the Coquimbo region, Chile. We assessed local-scale variables that may predict the number of interactions between dogs and foxes, and compared the time interval between dog-culpeo and dog-chilla interactions. Our findings suggested that closeness to urbanized zones predicts the frequency of indirect interactions between dogs and foxes. We found higher number of dog-fox interactions (60 interactions) at a periurban site adjacent to two coastal towns (Tongoy and Guanaqueros), compared to other two more undisturbed sites (12 interactions) increasingly distanced from urbanized areas. We showed that dogs interacted more frequently with chilla foxes (57 interactions) than with culpeo foxes (15 interactions), and the first interaction type occurred almost exclusively at the periurban site, where dogs and chillas were more frequently detected than in the other sites. We detected a marked temporal segregation between dogs and foxes, but dog-chilla interactions resulted in shorter time intervals (2.5 median days) compared to dog-culpeo interactions (7.6 median days), suggesting a higher potential risk of pathogen spillover between the first species pairing. Based on previous studies, we suggest periurban zones may constitute a potential focus of pathogen exposure between dog and fox populations in the study area. Our research contributes to improving the knowledge on the spatio-temporal patterns of interspecific contact between invasive and native carnivores within the context of multi-host pathogen dynamics. Our outcomes will inform theoretical epidemiological models designed to predict and minimize the contact risk between domestic and threatened species, guiding effective control strategies at the wildlife-domestic interface.

Reduced tillage, cover crops and organic amendments affect soil microbiota and improve soil health in Uruguayan vegetable farming systems.

Conventional tillage and mineral fertilization (CTMF) jeopardize soil health in conventional vegetable production systems. Using a field experiment established in Uruguay in 2012, we aimed to compare the soil restoration potential of organic fertilization (compost and poultry manure) combined with conventional tillage and cover crop incorporated into the soil (CTOF) or with reduced tillage and the use of cover crop as mulch (RTOF). In 2017, table beet was cultivated under CTMF, CTOF and RTOF, and yields, soil aggregate composition and nutrients, as well as soil and table beet rhizosphere microbiota (here: bacteria and archaea) were evaluated. Microbiota was studied by high-throughput sequencing of 16S rRNA gene fragments amplified from total community DNA. RTOF exhibited higher soil aggregation, soil organic C, nutrient availability and microbial alpha-diversity than CTMF, and became more similar to an adjacent natural undisturbed site. The soil microbiota was strongly shaped by the fertilization source which was conveyed to the rhizosphere and resulted in differentially abundant taxa. However, 229 amplicon sequencing variants were found to form the core table beet rhizosphere microbiota shared among managements. In conclusion, our study shows that after only 5 years of implementation, RTOF improves soil health under intensive vegetable farming systems.

Contrary to vertebrates, less aggressive and more consistent individuals are common in disturbed habitats in the colonial spider Metabus gravidus (Araneae: Araneidae)

Abstract Habitat disturbance may affect average behavioural types and consistency/plasticity of behaviour. Studies with solitary vertebrates suggest that human-modified habitats may favour bolder, more aggressive and more plastic individuals. We evaluated whether wild colonial spiders, Metabus gravidus, vary in the magnitude, consistency and plasticity of boldness and aggressiveness between an undisturbed forest and an adjacent urban area in Monteverde, Costa Rica. Repeatability of aggressiveness was high at the disturbed site but moderate at the undisturbed site; repeatability of boldness was low at both sites. Individual and population plasticity was similar between sites for both behaviours. Aggressiveness decreases with increasing colony size at the disturbed site; this trend was not observed at the undisturbed site. Boldness did not change with colony size. In contrast to solitary animals, our results indicate that less aggressive and more consistent colonies may have an advantage living in human-disturbed habitats.