Levels Of Disturbance Research Articles

Neuromorphic deep learning frequency regulation in stand-alone microgrids

Frequency instability has been a growing problem in recent years due to the rising penetration of distributed generating systems in the format of Microgrids (MGs), which are powered by renewable energy sources (RESs) with an unpredictable nature. The provision of an effective load frequency control (LFC) to an MG model under such conditions contributes significantly to the restoration regarding the unconfigured power system’s stability. An MG structure is employed, which combines renewable energy sources like solar and wind, as well as biologically renewable sustainable energy sources like wastewater, agricultural and domestic wastes, and contains appropriate battery systems and is suited to achieve both energy and waste control in this study. In addition, redox flow battery (RFB), an innovative battery storage system with a fast dynamic response in this MG structure, has been considered as one of the energy storage devices. A nonlinear integral backstepping (NIB) controller is adopted to stabilize the frequency deviation of the integrated MG system with RFB under various level of load disturbances and randomness of RESs. In particular, a spike neural network (SNN) based on neuromorphic platform is proposed to adjust the coefficients of NIB controller. Furthermore, real time analyses are performed with OPAL-RT to validate the feasibility of the proposed strategy from a systematical viewpoint. As a result of this study, the proposed controller for load disturbance, RES power changes, and contingency circumstances in bio renewable MG is determined to be flexible enough to satisfy the efficient frequency regulation for these grids.

H ∞ performance analysis for 2D discrete singular stochastic systems

This paper addresses the problem of H∞ performance analysis of 2D discrete singular stochastic system described by Roesser model which is challenging since it involves 2D random variables and the disturbance simultaneously. Sufficient conditions are established for the regularity, causality and stability of the system. The proposed results are expressed in terms of strict linear matrix inequalities. Furthermore, a mean square asymptotic stability with an H ∞ disturbance level is developed. Simulation example is provided in order to illustrate the relevance of our approach.

A Longitudinal Study of Sleep Habits and Leukemia Incidence Among Postmenopausal Women.

We sought to assess the relationship between sleep duration, sleep disturbance, and leukemia incidence among postmenopausal women. This study included 130,343 postmenopausal women aged 50-79 years who were enrolled in the Women's Health Initiative (WHI) during 1993-1998. Information on self-reported typical sleep duration and sleep disturbance was obtained by questionnaire at baseline, and sleep disturbance level was defined according to the Women's Health Initiative Insomnia Rating Scale (WHIIRS). WHIIRS scores of 0-4, 5-8, and 9-20 comprised 37.0%, 32.6%, and 30.4% of all women, respectively. After an average of 16.4 years (2,135,109 cumulative person-years) of follow-up, 930 of the participants were identified as having incident leukemia. Compared with women with the lowest level of sleep disturbance (WHIIRS score 0-4), women with higher sleep disturbance levels (WHIIRS scores of 5-8 and 9-20) had 22% (95% confidence interval (CI): 1.04, 1.43) and 18% (95% CI: 1.00, 1.40) excess risks of leukemia, respectively, after multivariable adjustment. A significant dose-response trend was found for the association between sleep disturbance and leukemia risk (P for trend = 0.048). In addition, women with the highest level of sleep disturbance had a higher risk of myeloid leukemia (for WHIIRS score 9-20 vs. WHIIRS score 0-4, hazard ratio = 1.39, CI: 1.05, 1.83). Higher sleep disturbance level was associated with increased risk of leukemia, especially for myeloid leukemia among postmenopausal women.

Vineyard floor management intensity impacts soil health indicators and plant diversity across South Australian viticultural landscapes

Throughout the last thirty years, major shifts in vineyard floor management have been observed. Challenges initially posed by intensive tillage included high rates of soil erosion and the degeneration of soil structure and soil organic matter, which lead viticulturists to depend more heavily on herbicide use as an effective weed control strategy. However, an increase in herbicide persistence and toxicity in water, soils, and grapevines, increasing resistance of common weeds; and pressure from consumers and regulators to reduce their use is directing a shift towards an overall reduction in herbicide usage. This has led to more frequent tillage to manage vegetation in vineyards, while in some instances, cultural practices including slashing and animal grazing are used solely or in conjunction. However, little is known about the holistic effects of these varying practices on vineyard soils and biodiversity across landscapes in Australia. Thus, to comparatively assess the environmental impacts of different floor management practices, soil health indicators and plant dynamics were seasonally measured in the mid- and under-vine rows at twenty-four vineyard sites and four native sites in the Barossa Valley, Eden Valley, and McLaren Vale, all located in South Australia, where different intensities of floor management were implemented. Vineyard sites were categorised based on the frequency of herbicide and/or tillage passes particularly in the under-vine area into Low (no annual management passes), Medium (one annual management pass), and High (two to four annual management passes) intensity groups. Findings revealed similarities in the vineyard mid-rows across the management intensities, yet the under-vine rows displayed many differences; in particular, there were more plant species, higher plant coverage, and greater plant biomass in the Low management intensity group. Furthermore, as management intensity decreased, the relative richness of ruderal plant species also decreased, giving way to a plant community mainly comprised of slow-growing, perennial Poaceae and Fabaceae species in the Low-intensity management group. These differences in plant dynamics drove a suite of soil responses including faster water infiltration, higher soil ammonium-N and total nitrogen, and a tendency of higher soil gravimetric water content at the time of sampling. These results suggest that after an initial period of establishing these more extensive vineyard floor management practices, low levels of soil disturbance in the under-vine rows may contribute positively to improving natural ecosystem synergy and functionality between soil and plants. Therefore, our findings lend insights into how the varying intensity of floor management practices, rather than differing management ideologies per se, across a viticultural landscape can be intrinsic supporters of agroecosystem resilience under South Australian conditions.

Spatial and temporal changes of subtidal benthic communities in Antofagasta Bay (SE Pacific) stressed by permanent human disturbances

Human activities have impacted the coastal area of Antofagasta Bay for decades, particularly miners’ activities (loading of mineral concentrates of Cu, Zn, Pb, and Mg), port operations, tourism, desalination plants, artisanal fishing, and sewage discharge. Subtidal coastal benthic communities were assessed in 7 sectors with different magnitudes of anthropogenic disturbances between the years 2008 to 2011 at Antofagasta Bay. Transennella pannosa, Incatella cingulata, Crassilabrum crassilabrum, and Leukoma thaca dominated the communities in all years of study. Based on the type of feeding behavior, the highest biomass was evidenced for the suspensivore group in all years of study, followed by the carnivore species. The highest average richness and average Shannon diversity were observed in sectors with medium and high levels of disturbances. In contrast, the highest average species dominance was registered in a sector with low disturbances. Community structure differed significantly between the seven sectors over the four years. The analysis of classification and ordination showed the conformation of three groups of sectors based on their dissimilarities. The differences were best explained by the sectors with low and high disturbances and by the presence of bivalves, ascidians, gastropods, and algae. It was demonstrated that the reduction or absence of fishing pressure could explain species’ high richness and diversity. Likewise, the sectors under low disturbance pressure showed the highest biomass and dominance of species. The information obtained in the current work could be used to design management strategies for conservation, monitoring, and restoration programs.

Habitat preference of leopard cat (Prionailurus bengalensis Kerr. 1792) in the Cisokan Hydropower Development Area, West Java, Indonesia

Abstract. Shanida SS, Megantara EN, Husodo T, Mutaqin AZ, Kendarto DR, Wulandari I. 2023.Habitat preference of leopard cat (Prionailurus bengalensis Kerr. 1792) in the Cisokan Hydropower Development Area, West Java, Indonesia. Biodiversitas 24: 2284-2293. Leopard cat (Prionailurus bengalensisKerr. 1792) can occupy various habitats, including degraded and human-modified landscapes such as agricultural lands, plantations, and settlements. Nonetheless, there is little information about their responses to infrastructure development impacts the habitat preference of leopard cats. This study aims to reveal the habitat preferences of leopard cats in the Upper Cisokan Pumped Storage (UCPS) hydropower development area, Cianjur Regency and West Bandung Regency, West Java. Direct observation was conducted to collect habitat preference in terms of biotic, abiotic and anthropogenic parameters and analyzed using Vanderploeg and Scavia's Resource Selection Index (VSI). The results showed that in term of biotic factors, leopard cats preferred natural forests, shrubs, and rice fields; tree canopy area of ??51%-75%, tree DBH >20 cm, tree height 0-5 m and 11-15 m, and tree density of 0-20 trees. Leopard cats preferred 76%-100% shrubs canopy; ground-plant cover of 26%-75% with withered grass cover of 76%-100%. According to their abiotic factors, leopard cats preferred habitats with north and south, gentle, and lower slopes. The leopard cats also preferred habitat with wet soil. In term of anthropogenic factors, leopard cats preferred habitat close to water sources (<500 m). Leopard cats chose habitats with moderate distances (500 m-1000 m) from anthropogenic disturbances with weak intensity. Agricultural activities could affect its habitat preference directly. Leopard cats were found at various levels of disturbance in human-modified lands, such as rice fields and shrublands. Since the main prey is cosmopolitan animals, as long as there is human-modified land, prey availability will remain guaranteed. Although the leopard cat can tolerate anthropogenic disturbances, there is little information on the direct impact of construction activities on this population, so further research is needed to observe their population and habitat in the construction area.

Key-value data collection and statistical analysis with local differential privacy

The collection and statistical analysis of simple data types (e.g., categorical, numerical and multi-dimensional data) under local differential privacy has been widely studied. Recently, researchers have focused on the collection of the key-value data, which is one of the main types of NoSQL data model. In the collection and statistical analysis of key-value data under local differential privacy, the frequency and mean of each key must be estimated simultaneously. However, achieving a good utility-privacy tradeoff is difficult, because key-value data has inherent correlation, and some users may have different numbers of key-value pairs. In this paper, we propose an efficient sampling based scheme for collecting and analyzing key-value data. Note that the more valid data collected, the higher the accuracy of statistical data under the same disturbance level and disturbance algorithm. Therefore, we make full use of probability sampling and the inherent correlation of key-value data to improve the probability of users submitting valid key-value data. Moreover, we optimize the budget allocation on key-value data, so that the overall variance of frequency and mean estimation is close to optimal. Detailed theoretical analysis and experimental results show that the proposed scheme is superior to existing schemes in accuracy.

Effects of Different Types of Soil Management on Organic Carbon and Nitrogen Contents and the Stability Index of a Durum Wheat–Faba Bean Rotation under a Mediterranean Climate

Soil quality, nitrogen, and organic matter content are increasingly being researched due to their impact on the environment. We assessed the effects of different soil management practices on the distribution and accumulation of soil organic carbon (SOC) in a durum wheat–faba bean rotation system cultivated in a Mediterranean-type area of Southern Italy, over six years. The effects of three levels of soil disturbance—conventional tillage (CT), minimum tillage (RT), and no tillage—(NT) on the SOC and nitrogen (N) content at soil depths of 0–15, 15–30, 30–60, and 60–90 cm were compared in a long-term experiment starting in the 2009–2010 growing season. The three soil management systems showed significant differences (p < 0.05) in the surface layer (0–15 cm depth) in SOC content and total nitrogen, with the largest accumulation occurring in the conservation system (NT). In the deep layers (30–60 and 60–90 cm), however, no significant differences were found between the three tillage systems. The ascending order of the tendency to accumulate SOC and N in the soil in the 0–15 cm layer was NT > CT > RT. In addition, the C/N ratio showed a more equilibrated rate in the NT system. The conservation tillage (NT) gave the best results in terms of the physical characteristics of the soil, showing a higher stability index compared to CT and RT. Conservation tillage is therefore recommended for wheat cultivation in the dry areas of Southern Italy, due to its benefits in terms of both crop yield improvements and environmental protection.

Dapagliflozin modulates neuronal injury via instigation of LKB1/p-AMPK/GABAB R2 signaling pathway and suppression of the inflammatory cascade in an essential tremor rat model

ABSTRACT Background However, disturbances in cellular energy demarcate neuronal hyperexcitability in essential tremor (ET); nevertheless, no available data relates energy sensors and GABAergic neurotransmission in ET. Noteworthy, reports have asserted dapagliflozin’s (DAPA) role in enhancing autophagic sensors in other disorders. Herein, this study aims to investigate DAPA’s impact on the GABAB receptor subunit (GABAB R2), notwithstanding the GABA A involvement, in an ET model. Methods ET was induced by a single dose of harmaline (30 mg/kg; i.p.), while DAPA (1 mg/kg/day; p.o.) was given for 5 days before ET induction. The autophagic sensors were examined by injecting a single dose of dorsomorphin (DORSO) AMPK inhibitor (0.2 mg/kg; i.p.) on the 5th day before ET induction. Results DAPA decreased the HAR-induced tremor score and alleviated motor disabilities observed in the open field, rotarod, wire grip strength, and gait kinematics confirmed by reduced electrical activity in electroencephalogram. In the cerebella, DAPA curbed HAR-evoked inflammatory cytokines, apoptotic markers, and glutamate while restoring the disturbed GABA, BDNF, LKB1, p-AMPK, and GABAB R2 levels. DAPA’s effect was mostly obliterated by DORSO. Conclusion DAPA offers a potential neuroprotective effect in ET by augmenting the neuronal inhibitory machinery via suppressing the inflammatory and excitotoxicity systems through LKB1/p-AMPK/GABAB R2 signaling.

0683 Sleep disturbance, social functioning, and suicidal ideation among preadolescent children admitted to intensive psychiatric care

Abstract Introduction Research on preadolescent childhood suicidality is sparse, with recent population-based studies providing support for sociodemographic and diagnostic correlates of preadolescent suicidal ideation. Sleep disturbance is of particular interest in the examination of preadolescent suicidal ideation because sleep health is interlinked with childhood psychosocial functioning; further, there are changes in preadolescent homeostatic regulation of sleep-wake and intrinsic circadian rhythm (i.e., delayed sleep onset), and psychosocial pressures in preadolescence, such as bedtime autonomy, that are increasingly manifested. There is a need to test models that begin to delineate associations between sleep disturbance and childhood suicidal ideation, specifically among youth with early-onset psychopathology. One possible explanatory factor in the association between sleep disturbance and suicidal ideation, grounded in existing theoretical frameworks of suicide, is social functioning (e.g., developmentally appropriate peer interactions and connectedness). The current study tested an indirect effects model in which sleep disturbance is associated with suicidal ideation via social functioning. Methods 223 children (ages 7–12) with severe psychopathology who presented for intensive hospital-based treatment and their caregivers completed an assessment battery at admission, including the parent-reported sleep disturbances via the Children’s Sleep Habits Questionnaire, and child-reported dysregulated negative affect, social functioning, and suicidal ideation. Indirect effects were examined via the PROCESS macro for SPSS Version 4.0. Binary logistic regression was used when suicidality served as the dependent variable. All models controlled for youth age and dysregulated negative affect. Results Higher levels of parent-reported youth sleep disturbances were related to lower levels of youth-report social functioning. Further, lower levels of social functioning and higher levels of sleep disturbances were associated with higher odds of endorsing suicidal ideation. Indirect effects analyses indicated that higher levels of sleep disturbances was associated with increased odds of reporting suicidal ideation via the detrimental impact of sleep disturbances on social functioning. Conclusion The findings support the novel extension of explanatory models of suicide to children and highlight the possible role of sleep disturbance in the etiology of early suicidality. Documenting these associations provides the impetus for fine-grained examination of sleep health and social functioning among children who experience suicidal ideation and severe psychopathology. Support (if any)

Disturbance Injection Under Partial Automation: Robust Imitation Learning for Long-Horizon Tasks

Partial Automation (PA) with intelligent support systems has been introduced in industrial machinery and advanced automobiles to reduce the burden of long hours of human operation. Under PA, operators perform manual operations (providing actions) and operations that switch to automatic/manual mode (mode-switching). Since PA reduces the total duration of manual operation, these two action and mode-switching operations can be replicated by imitation learning with high sample efficiency. To this end, this paper proposes Disturbance Injection under Partial Automation (DIPA) as a novel imitation learning framework. In DIPA, mode and actions (in the manual mode) are assumed to be observables in each state and are used to learn both action and mode-switching policies. The above learning is robustified by injecting disturbances into the operator's actions to optimize the disturbance's level for minimizing the covariate shift under PA. We experimentally validated the effectiveness of our method for long-horizon tasks in two simulations and a real robot environment and confirmed that our method outperformed the previous methods and reduced the demonstration burden.

Disturbances in the Magnetosphere and Ionosphere during Spotless Sun

Analysis of geomagnetic and ionospheric activity is performed for 541 disturbed days during spotlessSun (Kp 3.0) from 1995 to 2021. Variations of the global ionospheric indices WU (positive disturbancesof total electron content), WL (negative disturbances), their range WE and the planetary index Wp are analyzed.The source W-index characterizes a measure of deviation of the instant total electron content from thequiet median varying from −4 to +4 with a step 1, and the global indices WU, WL, WE, Wp are derived fromthe global maps GIM-TEC of Jet Propulsion Laboratory, JPL. Investigation of the seasonal dependence hasrevealed two levels of the ionosphere disturbances: the low disturbance of the ionosphere during 1996‒1998and 2018‒2021 and the high disturbance during 2004‒2010 and 2016‒2017. The seasonal ionosphere variationsare different for two sets of the data. The seasonal variations of the solar wind velocity Vsw near the Earthorbit are first identified for the 1st data set displaying the peaks at the equinoxes similar to variations of theKp-index. The 2nd set of the high disturbance of the ionosphere refers to the epoch of transition from the highsolar activity SA to low SA characterized by the total restructuring of the physical conditions on the Sun

Dietary overlap and selectivity among mountain steppe river fish in the United States and Mongolia.

Lotic systems in mountain regions have historically provided secure habitat for native fish populations because of their relative isolation from human settlement and lack of upstream disturbances. However, rivers of mountain ecoregions are currently experiencing heightened levels of disturbance due to the introduction of nonnative species impacting endemic fishes in these areas. We compared the fish assemblages and diets of mountain steppe fishes of the stocked rivers in Wyoming with rivers in northern Mongolia where stocking is absent. Using gut content analysis, we quantified the selectivity and diets of fishes collected in these systems. Nonnative species had more generalist diets with lower levels of selectivity than most native species and native species had high levels of dietary specificity and selectivity. High abundances of nonnative species and high levels of dietary overlaps in our Wyoming sites is a cause of concern for native Cutthroat Trout and overall system stability. In contrast, fish assemblages characterizing Mongolia mountain steppe rivers were composed of only native species with diverse diets and higher selectivity values, suggesting low probability for interspecific competition.

Synergy Among the Indonesia Maritime Security Institutions in Conducting Maritime Patrol

Maritime patrols are necessary because Indonesia is vulnerable to maritime threats and disturbances. Patrols are not optimally covered the sea and the regulations are not comprehensive to be synergy guidelines. This article discusses how to synergize effective and efficient patrols at the six maritime security institutions, and finally reduce the level of threats and disturbances to maritime security. This article uses qualitative methods and synergy models, interviews were conducted with informants from six maritime security institutions. Various elements of the patrol require collaboration consisting of personnel, assets, and ideas from various institutions. The advantages of an institution that should be utilized together include the size of the budget or assets, personnel militancy, social patrols, targeting patrols, aerial monitoring, and shipping court mechanisms. Trust exists from long-standing interactions to see competence and integrity, not by coercion of regulations. Leaders must meet all the criteria for leaders, both those who want strong criteria and those who want accountability or integrity or can accept criticism. Maritime patrol synergy is formed by the interaction of collaboration, engagement, trust components, and leadership support to ensure the synergy runs.

Plant Diversity in the Diet of Costa Rican Primates in Contrasting Habitats: A Meta-Analysis

In human-modified tropical landscapes, the survival of arboreal vertebrates, particularly primates, depends on their plant dietary diversity. Here, we assess the diversity of plants included in the diet of Costa Rican non-human primates, CR-NHP (i.e., Alouatta palliata palliata, Ateles geoffroyi, Cebus imitator, and Saimiri oerstedii) inhabiting different habitat types across the country. Specifically, we analyzed 37 published and unpublished datasets to assess: (i) richness and dietary α-plant diversity, (ii) the β-diversity of dietary plant species and the relative importance of plant species turnover and nestedness contributing to these patterns, and (iii) the main ecological drivers of the observed patterns in dietary plants. Dietary data were available for 34 Alouatta, 16 Cebus, eight Ateles, and five Saimiri groups. Overall dietary plant species richness was higher in Alouatta (476 spp.), followed by Ateles (329 spp.), Cebus (236 spp.), and Saimiri (183 spp.). However, rarefaction curves showed that α-diversity of plant species was higher in Ateles than in the other three primate species. The γ-diversity of plants was 868 species (95% C.I. = 829–907 species). The three most frequently reported food species for all CR-NHP were Spondias mombin, Bursera simaruba, and Samanea saman, and the most consumed plant parts were leaves, fruits, and flowers. In general, plant species turnover, rather than nestedness, explained the dissimilarity in plant diet diversity (βsim > 0.60) of CR-NHP. Finally, primate species, habitat type (life zone and disturbance level) and, to a lesser degree, study province, were the best predictors of the dietary plant assemblages. Our findings suggest that CR-NHP diets are diverse, even in severely disturbed habitats.

Characteristics of the Stone Crayfish Population along a Disturbance Gradient—A Case Study of the Kustošak Stream, Croatia

The stone crayfish, Austropotamobius torrentium, is a native European freshwater species sensitive to habitat alterations such as stream channelization and urban development, putting its populations at risk. This study aims to assess how habitat alteration and subsequent water quality changes affect the stone crayfish population in the Kustošak Stream (Croatia) through three selected sites under different levels of anthropogenic disturbance: (1) undisturbed; (2) recently modified, and (3) long-time modified sites. At each site, crayfish were captured, measured, and marked to estimate population size, structure, and crayfish condition. Additionally, we examined whether water quality (18 measured physicochemical parameters) affects relative crayfish abundance. We also used mitochondrial sequencing and microsatellite genotyping to assess species genetic diversity and population connectivity and to compare results among the sites. The results showed that habitat alteration caused an overall reduction in population abundance and changes in size structure; however, it had not yet resulted in detectable genetic differences. Partial least squares regression showed that crayfish abundance was affected by the physicochemical parameters of water, including, among others, oxygen, calcium ions, nitrates, pH, and water temperature. We discuss our findings in the context of the effects of anthropogenic disturbance on the viability and persistence of this EU priority species.

Effects of human disturbance on risk‐taking behavior in painted turtles

AbstractAnimals are exposed to high levels of anthropogenic disturbance, which has profound consequences for population persistence. Individuals can adjust their behavior plastically when faced with perturbations in their environment and may show consistent differences in the way they perceive and respond to risky situations. Over time, this variability among individuals in response to risk can affect the dynamics of populations exposed to human disturbance. Thus, understanding how animals cope behaviorally with human disturbance is important, especially for species vulnerable to human perturbations, such as turtles. In this context, we evaluated whether risk‐taking behaviors are consistent within individual painted turtles (Chrysemys picta) and assessed how these behaviors are related to the extent of human disturbance along the Rideau Canal, Ontario, Canada. Specifically, we conducted repeated measurements of the number of active defensive behaviors used during handling and the time taken to escape a floating platform for 730 painted turtles (1117 observations) from 22 sites varying in human disturbance along the canal. We also quantified the emergence of the turtles from the water after escaping the platform. First, individual painted turtles showed consistent differences in all risk‐taking behaviors. Second, painted turtles in areas with high boat activity displayed more active defensive behaviors, while turtles from sites in proximity to more houses with access to the canal used fewer. Our study highlights the importance of studying animal behavior to better understand the impact of human activities on animal populations.

The Spatiotemporal Changing Dynamics of Miombo Deforestation and Illegal Human Activities for Forest Fire in Kundelungu National Park, Democratic Republic of the Congo

In the Kundelungu National Park (KNP), southeast of the Democratic Republic of Congo, illicit human activities including recurrent bushfires contribute to constant regression of forest cover. This study quantifies the landscape dynamics and analyses the spatio-temporal distribution of bushfire occurrence within KNP. Based on classified Landsat images from 2001, 2008, 2015 and 2022, the evolutionary trend of land cover was mapped and quantified through landscape metrics. The spatial transformation processes underlying the observed landscape dynamics were identified based on a decision tree. Finally, the spatio-temporal fire risk assessment was carried out after defining the burnt areas for each year between 2001 and 2022. The obtained results, expressed by the process of dissection and attrition of patches, show that the forest cover has regressed from 2339 km2 to 1596 km2 within the PNK, with an annual deforestation rate varying from 0.8% to 3.4% between 2001 and 2022. Over the same period, the average distance between forest patches has increased significantly, indicating fragmentation and spatial isolation. On the other hand, savannahs as well as field and fallow mosaics have expanded within KNP through the creation of new patches. In addition, several active fires affected more savannahs between 2001 (70 km2 in Integral Zone, 239 km2 in Annex Zone and 309 km2 in KNP) and 2022 (76 km2 in Integral Zone, 744 km2 in Annex Zone and 819 km2 in KNP), limiting their capacity to evolve into forests. Overall, anthropogenic pressure is higher in the Annex Zone of the KNP. Illegal agricultural development and vegetation fires have thus doubled the level of landscape disturbance in 21 years. Our observations justify the need to strengthen protection measures for KNP by limiting repeated human intrusions.

Determination of optimal tree height models and calibration designs for Araucaria araucana and Nothofagus pumilio in mixed stands affected to different levels by anthropogenic disturbance in South-Central Chile

Key messageHere, we present a workflow for determining the optimal tree height model and calibration design for forests affected to varying degrees by anthropogenic disturbance. For mixed Araucaria-Nothofagus forests, tree height predictions in newly surveyed stands are most accurate and effective when the height of up to five random trees is measured to recalibrate predefined nonlinear mixed-effects models.ContextAraucaria-Nothofagus forests in Chile are affected by anthropogenic disturbances such as intentional forest fires, grazing, and seed harvesting, causing forest structure to become more heterogeneous. This also challenges tree height predictions, which are required for yield estimations, carbon accounting, and forest management, since height measurements of standing trees are often considered too costly, difficult, and imprecise.AimsHow does the structure of these forests vary by different levels of anthropogenic disturbance? Which models for estimating tree height of Araucaria araucana and Nothofagus pumilio are most reliable and generally usable? And considering their application in stands they have not been fitted to, which calibration design is optimal for these models?MethodsTwelve stands were surveyed and classified into four different intensities of anthropogenic disturbance. In 25 to 36 plots per stand, horizontal point sampling measurements of stem diameter as well as of height of selected trees were carried out. Different quantitative stand-level properties were calculated to determine forest structure, which was compared among stands by cluster analysis. To identify the optimal height-diameter (H–D) model, simple models including diameter only as well as generalized models including stand variables were tested, each additionally extended by a nonlinear mixed-effects (NLME) modeling framework accounting for nested and random effects. To further determine tree height in new stands, the optimal model calibration design was identified involving the empirical best unbiased predictor technique.ResultsForest structure greatly varied among stands affected by different levels of anthropogenic disturbance, which challenged the development of tree height prediction models. Of all the simple H–D models considered, the Gompertz model was the best for A. araucana and the Näslund model for N. pumilio. The models progressively improved by adding stand variables and using NLME techniques. However, our final model comparisons indicate that a calibrated simple NLME model without stand variables should be preferred. It was further found that the optimal calibration design is to use five randomly selected trees.ConclusionAlthough anthropogenic disturbances can have a complex effect on height-diameter relationships, the same H–D model can be used for stands representing different anthropogenic disturbance levels and recalibrated by cost-effective measurements.

Analysis of Bacterial Communities around the Adventdalen Landfill Site in Svalbard.

Ecosystems are often resilient enough to fully recover following a natural disturbance, or to transform into a new equilibrium favourable to the surrounding flora and fauna. However, at a local level, whether this transformation will be beneficial or not depends strongly on the level of disturbance and the available mechanisms for recovery. The Arctic, however, provides a potentially extreme environment for microbial growth and this is reflected in the microbial biodiversity, the in-situ growth rates, the biogeochemical cycling and its sensitivity to environmental change. In this study, we evaluated the current microbial biodiversity and environmental conditions around the landfill site in Adventdalen, Svalbard to identify differences across bacterial communities that might promote or accelerate naturally occurring environmental recovery. Landfill sites can induce changes in the local environment through the input of exogenous chemicals (both organic and inorganic) and microorganisms. Leachate can flow with run-off from the primary location of the landfill site due to rain, snow or ice melt and spread material into soils surrounding the site. In this study we found a strong effect of the landfill site on the bacterial diversity in the local landscape. Intervention is highly desirable to enhance the environment and improve the restoration by subtly altering the conditions at the site (such as the pH or drainage courses) and by encouraging specific groups of naturally occurring indigenous microorganisms to bioremediate the site.