Years Of Monitoring Data Research Articles

Does ant-plant mutualism have spillover effects on the non-partner ant community?

Mutualism benefits partner species, and theory predicts these partnerships can affect the abundance, diversity, and composition of partner and non‐partner species. We used 16 years of monitoring data to determine the ant partner species of tree cholla cacti (Cylindropuntia imbricata), which reward ants with extrafloral nectar in exchange for anti‐herbivore defense. These long‐term data revealed one dominant ant partner (Liometopum apiculatum) and two less common partners (Crematogaster opuntiae and Forelius pruinosus). We then used short‐term characterization of the terrestrial ant community by pitfall trapping to sample partner and non‐partner ant species across ten plots of varying cactus density. We found that the dominant ant partner tended a higher proportion cacti in plots of higher cactus density, and was also found at higher occurrence within the pitfall traps in higher density plots, suggesting a strong positive feedback that promotes ant partner occurrence where plant partners are available. Despite the strong association and increased partner occurrence, ant community‐wide effects from this mutualism appear limited. Of the common ant species, the occurrence of a single non‐partner ant species was negatively associated with cactus density and with the increased presence of L. apiculatum. Additionally, the composition and diversity of the ant community in our plots were insensitive to cactus density variation, indicating that positive effects of the mutualism on the dominant ant partner did not have cascading impacts on the ant community. This study provides novel evidence that exclusive mutualisms, even those with a strong positive feedback, may be limited in the scope of their community‐level effects.

Plant size and neighbourhood characteristics influence survival and growth in a restored ex‐agricultural ecosystem

Abstract Restoring woody vegetation on degraded agricultural land is a widespread and common ecological restoration practice. However, highly variable plant survival and growth limit outcomes for many projects. Inconsistent reporting and monitoring of projects mean that an assessment of the relative importance of community‐assembly processes is limited, particularly over longer timescales. We use 7 years of monitoring data of nearly 2000 native trees and shrubs in a restoration project on ex‐agricultural land in south‐western Australia to test the potential effects of facilitation or competition from neighbouring plants, as well as look for patterns in their interaction with the attributes of individuals and species traits. Overall, plant size was the strongest single predictor of survival and incremental growth. Individual plants in neighbourhoods with higher inter‐generic basal area were more likely to survive, with this effect strongest in smaller individuals. When plants were larger, they were less likely to grow when in neighbourhoods with high intra‐generic basal area. Taller‐growing plants (higher species maximum height) were more likely to survive when individuals were small (basal area of 1–10 cm2), compared with shorter growing plants. Growth was also more likely in taller‐growing plants, and this relationship increased with the size of the individual. Recruitment was very low, with just 148 new recruits recorded across the 42 plots over 7 years. Maximizing the growth of plants in restorations in the early stages may promote survival and growth in the longer term. We also demonstrate that increased levels of inter‐generic neighbouring plants may improve individual plant survival in the restoration of ex‐agricultural land. As a result, we suggest tailoring direct‐seeding methods to minimize clustering of congeneric individuals. We also highlight the need to find means of promoting recruitment for the long‐term sustainability of restoration efforts.

Twenty-Five Years of Domoic Acid Monitoring in Galicia (NW Spain): Spatial, Temporal and Interspecific Variations.

Prevalence, impact on shellfish resources and interspecific, spatial, and temporal variabilities of domoic acid (DA) in bivalves from Galicia (NW Spain) have been studied based on more than 25 years of monitoring data. The maximum prevalence (samples in which DA was detected) (100%) and incidence (samples with DA levels above the regulatory limit) (97.4%) were recorded in Pecten maximus, and the minimum ones in Mytilus galloprovincialis (12.6 and 1.1%, respectively). The maximum DA concentrations were 663.9 mg kg−1 in P. maximus and 316 mg kg−1 in Venerupis corrugata. After excluding scallop P. maximus data, DA was found (prevalence) in 13.3% of bivalve samples, with 1.3% being over the regulatory limit. In general, the prevalence of this toxin decreased towards the North but not the magnitude of its episodes. The seasonal distribution was characterized by two maxima, in spring and autumn, with the later decreasing in intensity towards the north. DA levels decreased slightly over the studied period, although this decreasing trend was not linear. A cyclic pattern was observed in the interannual variability, with cycles of 4 and 11 years. Intoxication and detoxification rates were slower than those expected from laboratory experiments, suggesting the supply of DA during these phases plays an important role.

Using machine learning to reveal spatiotemporal complexity and driving forces of water quality changes in Hong Kong marine water

A self-organizing map (SOM), which is an unsupervised neural network, is used to explore the spatiotemporal variability of water quality in Hong Kong marine water areas based on 31 years of monitoring data (1986–2016). In this study, three types of SOMs, referred to as s-v, s-t and t-s SOM, respectively, are applied to the multivariate marine water quality data, and principal component analysis (PCA) is used to help the clustering of SOM neurons and component planes. The major findings revealed by the spatiotemporal SOM analyses include the following: a) Hong Kong marine water areas can be classified into five regions with distinctive water quality characteristics over the long term, b) the spatiotemporal variations in chlorophyll-a (Chl-a) and NO3− are greatly affected by ocean currents and nutrients from Pearl River discharge, c) marine water quality is significantly affected by water control projects, e.g., the Hong Kong Harbor Area Treatment Scheme (HATS), and d) nitrogen (N) is the limiting nutrient for phytoplankton growth in winter, west and south of the Hong Kong marine regions, while phosphorus (P) is the limiting nutrient in summer, owing to the massive discharge of the Pearl River that contain NO3−. Furthermore, the severe pollution in Deep Bay with high levels of Chl-a, nutrients and fecal coliform (FC) deserves immediate attention from the governments. The results of this study prove that combined spatiotemporal SOM analyses provide a powerful tool to identify spatiotemporal patterns in water quality data and to reveal the driving forces behind water quality changes. This study presents the first attempt to apply SOMs to water quality analysis at both spatial and temporal domains.

A quarter-century of nutrient load reduction leads to halving river nutrient fluxes and increasing nutrient limitation in coastal waters of central Japan.

Nutrient load reduction is widely used to improve coastal water quality, but it can lead to oligotrophication. This paper evaluates the current status of river water origin and the water recharge system based on isotope values and dissolved compositions recorded in 2018, and it also assesses the impact of nutrient load reduction efforts on river nutrient fluxes and coastal water quality using 25years of monitoring data. This study focuses on the coast of Toyama Bay as a model area because (1) up to 20% of terrestrially derived nutrient support the growth of coastal primary productivity, and (2) the adjacent land is a typical city in a population-dense area (~ 500 persons/km2), a demographic characteristic that exists in 88% of Japan's total land area and 96% of the total length of the country's coastline. Since the government adopted new wastewater treatment systems in 1993, river nutrient supplies in the study area have been halved, while the total river flow and annual precipitation have remained almost unchanged. The reduction in riverine nutrient supply has increased phosphorus deficiencies in the coastal waters. Most notably, the decline in nutrient concentrations in coastal surface waters and the enlarged nutrient-restricted areas are facing most parts of Japan, suggesting a resulting 25-50% decrease in CO2 uptake by primary production. This study is in agreement with previous studies from various countries in emphasizing the importance of setting appropriate nutrient-management goals for maintaining a sustainable marine environment. This paper recommends the need to accumulate various case studies of different areas and to share in a timely manner scientific evidence on a regional and global scale.

A Bayesian approach to model selection and averaging of hydrostatic-season-temperature-time model

This paper presents a probabilistic approach to model the static dam responses, and monitor its performance using structural health monitoring (SHM) data. In general, the main factors that affects the dam responses are hydrostatic pressure, temperature changes, seasonal variation, and age-related deterioration. In this paper, using these variables two models (i.e., Model-1 and Model-2) have been developed to model, predict and monitor the dam performances. The Model-1 is a parsimonious model based on Bayesian model selection principle and can be applied if long-term monitoring data is available. On the other hand, Model-2 is an ensemble model which accounts for the model uncertainty and can be applied during the initial service-life with a few years of monitoring data. In both cases, the model parameters were estimated and updated using Bayesian method where the prior knowledge and SHM data obtained from dam are integrated. Finally, the model residuals i.e., the difference between the measured and predicted dam responses were used to detect any anomaly in the dam performance. The proposed method is illustrated through the crest displacement data obtained from Dongjiang dam located in China.

Driven by data: Improved protected area effectiveness in Royal Manas National Park, Bhutan

AbstractThe necessity of rangers and other frontline staff for ensuring the protection and effective management of protected areas is well documented. The Spatial Monitoring and Reporting Tool (SMART) was developed as a law enforcement monitoring tool with the aim of assisting management in the allocation of resources and strategic deployment of ranger patrols. The ability of SMART to contribute to improved protection depends heavily on effective application through an adaptive management framework. Royal Manas National Park (RMNP), Bhutan, presents an opportunity to review the use of a protected area law enforcement monitoring tool for improving the detection and reduction of illegal activities within a protected area through effective ranger patrols. Results from the analysis of 5 years of monitoring data collected by rangers indicates a marked improvement in patrol effort in RMNP and suggests that the effective deployment of law enforcement monitoring tools, when used as part of an adaptive management framework, can improve the detectability of poaching related threats, potentially resulting in an overall reduction of poaching threats through enabling the informed and targeted allocation of staff and resources.

Responses of the macrobenthic community to the Dalian Bay oil spill based on co-occurrence patterns and interaction networks

On July 16, 2010, a pipeline explosion spilled 1500 tons of crude oil into the Port of Dalian, China. To identify taxa responses to the spill, we exploited seven years of monitoring data to examine the co-occurrence of taxon pairs and the variation of the macrobenthic community. Non-parametric correlation analysis was used to construct interaction networks of relationships between oil spill contaminants and macrobenthic taxa.We observed that the impacted macrobenthic community not restored before 2016. The tolerance/sensitivity of taxa was inconsistent with the studies of oil impacts in other locations. We suggest revision of the ecological group classification of Sabellidae, Lumbrineridae, Terebellidae, Sternaspidae, and Spionidae. The variation in the frequency of coexistence indicates the potential impact of oil spill pollution on resource occupation. The interaction network involving macrobenthic families and stressors associated with the oil spill highlights how different macrobenthic families respond to different combinations of stressors.

Connecting targets for catchment sediment loads to ecological outcomes for seagrass using multiple lines of evidence

Catchment impacts on downstream ecosystems are difficult to quantify, but important for setting management targets. Here we compared 12 years of monitoring data of seagrass area and biomass in Cleveland Bay, northeast Australia, with discharge and associated sediment loads from nearby rivers. Seagrass biomass and area exhibited different trajectories in response to river inputs. River discharge was a slightly better predictor of seagrass indicators than total suspended solid (TSS) loads, indicating that catchment effects on seagrass are not restricted to sediment. Linear relationships between Burdekin River TSS loads delivered over 1–4 years and seagrass condition in Cleveland Bay generated Ecologically Relevant Targets (ERT) for catchment sediment inputs. Our predicted ERTs were comparable to those previously estimated using mechanistic models. This study highlights the challenges of linking catchment inputs to condition of downstream ecosystems, and the importance of integrating a variety of metrics and approaches to increase confidence in ERTs.

Aquaculture Development Monitoring on Mangrove Forest in Mahakam Delta, East Kalimantan

Aquaculture development is thriving to provide fish product demand. One-fifth of mangrove forest destruction in the coastal region is from aquaculture, where ninety percent occurred in South East Asia. The mangrove forest conversion for aquaculture development is also mirroring in Mahakam Delta which started in the early 1980s. In this paper, we examined the impact of aquaculture development in Mahakam Delta on the mangrove forest ecosystems using remote sensing. Thirty years of monitoring data were used using six Landsat images series (Landsat 5 and 8). The result found a massive development of aquaculture in the Mahakam Delta occurred in the late 1990s, in which 41% of mangrove forests converted into ponds. The unstable political situation in Indonesia and the decrease of rupiah exchange rate against the US dollar are the leading factors. Since the mid-2010s, aquaculture productivity has been declining and that many farmers decided to abandon their ponds. The condition made mangrove cover increase up to 4,000 hectares due to natural regeneration. Nevertheless, aquaculture ponds cover 54.8% of Mahakam Delta in 2020. To minimize the impact on the ecosystem, it needs to manage aquaculture sustainably with mangrove conservation.

Reliability Assessment for Time-Dependent Behaviour of Soft Soils Considering Cross Correlation between Visco-Plastic Model Parameters

An elastic visco-plastic creep model was combined with the Monte-Carlo probabilistic method incorporating multivariate copula and nonlinear analysis to investigate the effects of uncertainties in the elastic visco-plastic model parameters on time-dependent settlement and the distribution of excess pore water pressure in soft soils under applied loads. The elastic-plastic model parameter (λ/V) and creep coefficient (ψ0/V) were considered as random variables with lognormal distribution while considering the cross correlation between these two random variables. When λ/V and ψ0/V were used as random variables, the coefficient of variation of time-dependent deformation gradually decreased approximately 25% over time until reaching an asymptote. By adopting over 50 years of monitoring data from the case study of Väsby test fill and results from the settlement ratio, the most appropriate cross correlation coefficient between selected random variables was introduced. The results revealed that increasing the cross correlation coefficient between λ/V and ψ0/V increased the standard deviation and the coefficient of variation of settlement up to 40%. Meanwhile, the corresponding statistical features for the predicted excess pore water pressure decreased as the cross correlation coefficient increased. This study also provides a practical insight into selecting the most suitable cross correlation coefficient between elastic visco-plastic model parameters, while adopting reliability-based design approach that captures the time-dependent deformation of embankments and structures built on soft soils.

A demographic model to support an impact financing mechanism for black rhino metapopulations

Payment-for-results mechanisms have the potential to increase funding for Critically Endangered species such as the black rhino (Diceros bicornis). Developing such financial mechanisms requires an understanding of the efficacy of conservation interventions, the potential conservation return on investment and an ability to rigorously measure the impact of interventions, such as change in abundance of live or poached animals. However, imperfect detection must be considered to derive robust estimates of these measures. Managing black rhino is often done at the metapopulation level (in distinct management units) where ecological and observational processes can differ substantially between populations.We developed a multi-state capture-mark-resight model to estimate the abundance of live rhino and carcasses from annual historical observations. We used age, sex and management units as covariates. We used 25 years of monitoring data from two sections with contrasting rhino densities in Tsavo West National Park, Kenya as a test case. The model presented can be used to estimate abundances of rhino from historical data and provides a mechanism to measure changes across multiple management sections. We foresee this model being used as the basis for impact measurement of a rhino impact financing mechanism. The model can easily be modified for use in other species managed in a metapopulation framework.

Formation Mechanism and Stability Analysis of the Hejia Landslide

The existing research data show that, after reservoir impoundment, due to the repeated rise and fall of water level and water‐rock interaction, the mechanical parameters of landslide are reduced, which will have an adverse effect on the stability of landslide. Therefore, sufficient attention must be paid to the stability of slope after reservoir impoundment. Hejia landslide is the largest landslide near the bank of Miaojiaba hydropower station, and its stability plays an important role in the normal operation of the hydropower station. Through field investigation and analysis of regional geological conditions, it is concluded that Hejia landslide is a large‐scale landslide, through long‐term sliding‐bending deformation; it is generated from the external hard rock with thick layers and sliding zone for layered soft rock; the formation mechanism of landslide is as follows: (1) high‐steep and hard‐soft layered slope is the slope structure condition that caused the large landslide; (2) the existence of thick soft rock belt provides material conditions for the formation of slip surface; (3) certain air conditions provide displacement space for the separation and disintegration of the sliding body, and the landslide is stable at present. Numerical analysis results show that reservoir impoundment will adversely affect the stability of landslide. In order to ensure the normal operation of power station, certain engineering measures must be taken to treat Hejia landslide. After taking measures, years of monitoring data show that the deformation of Hejia landslide tends to be stable, and the current operation is normal, indicating that the engineering treatment measures are reasonable and feasible.

Winter in two phases: Long‐term study of a shallow reservoir in winter

AbstractClimate‐driven decreases in ice‐cover duration have the potential to impact lake ecosystems, yet we have only partial understanding of the effects of winter conditions on physical, chemical, and biological properties of lakes. We used 39 years of monitoring data to examine under‐ice changes in nutrients, oxygen, and phytoplankton in a shallow drinking‐water reservoir. Two phases of winter were identified. Early winter was characterized by declining oxygen. In this phase, there were increases in specific conductance and concentrations of ammonium (‐N) and soluble reactive phosphorus (SRP). In the month prior to ice off these trends reversed themselves and phytoplankton began to increase. Specific conductance declined as meltwater entered the lake. Nutrients (SRP and ‐N) declined, concurrent with increases in chlorophyll a and oxygen during late winter. This work demonstrates that chemical and biotic changes through winter are highly time dependent and differ between early and late winter phases. The late winter phase is often unstudied because of unsafe ice conditions, but here, the “spring” bloom commonly occurs in late winter under ice. The phases of winter, which are likely driven by changes in light, must be considered as we work to understand how diverse lakes will respond to declining periods of ice cover, and what drives differences in the spring ecology of diverse ice‐covered lakes.

Insight into the multi-decadal effects of floods on aquatic macroinvertebrate community structure in the Murray River using distributed lag nonlinear models and counterfactual analysis

We describe the multi-decadal delayed effects of flood on macroinvertebrate community structure using 33 years of monitoring data on macroinvertebrates, water quality, and climate, and 51 years of hydrological data, spanning 2300 km of the Murray River, Australia. We used distributed lag nonlinear models in a four-step analytical process, including 1) modelling macroinvertebrate community structure, represented as a set of principle coordinate axes, as a function of a lagged hydrologic index and other environmental variables using distance-based redundancy analysis 2) visualizing the patterns of delayed effects of flows on the PCO axes, 3) modelling the abundances of groups of taxa along individual PCO axes, and 4) combining the two sets of models in a counterfactual analysis to predict the community structure under flood and no-flood scenarios to describe the multi-decadal trajectory of the community following a flood. Our findings show an increase in abundance of most taxa of filtering-gathering collectors, scrapers, and shredders in the long term that implicates an influx of organic matter of all sizes, from particulate organic matter to coarse and large woody debris, that serves directly or indirectly as a food resource and/or habitat. Our approach enabled the isolation of a flood impact from the confounding effects of other flow events and environmental variables, overcoming a substantial challenge in ecohydrological studies.

Effects of climate and atmospheric deposition on a boreal lake chemistry: A synthesis of 36 years of monitoring data

Reduction in SO42− and NO3− atmospheric deposition in the past decades has improved surface water quality in several catchments but recent studies suggest an increasing influence of climate and dissolved organic carbon (DOC). Here, we report on long-term trends in climate variables, strong acid anions and base cations concentrations in precipitation and at the lake outlet (stream) of a boreal catchment in Québec, Canada, and assess the combined effects of these trends on stream chemistry. Annual SO42− and NO3− depositions respectively decreased by ~85% (from 23 to ~3 kg ha−1) and ~70% (from 18 to ~5 kg ha−1 yr−1) from 1981 to 2016. As a response, stream SO42− and Ca2+ concentrations decreased by 50% (from 3.9 to 1.9 mg L−1) and ~35% (from 2.4 to 1.5 mg L−1), respectively. Stream NO3− concentration decreased by ~89% (from 0.6 to 0.07 mg L−1) mainly due to the decline in NO3− deposition and possibly to increased vegetation N uptake. Unexpectedly, stream alkalinity decreased, likely due to the decline in Ca2+ concentration and to an increase in DOC concentration. Variations in stream pH and Na+ concentrations were best explained by climatic changes than by changes in acid deposition, likely reflecting the effect of climate change on chemical weathering in the region. In addition, the average daily temperature between May and September had a strong influence on stream Ca2+ concentration in the last two decades (negative relationship), suggesting an increasing vegetation nutrient uptake caused by improved growth conditions. Overall, decreased acidic deposition resulted in a general recovery of surface water although the parallel increase in DOC concentration prevented from an increase in water alkalinity. Our data also indicate an increasing influence of climate on water chemistry at the study site, probably mediated by increasing weathering rate and vegetation nutrient uptake.

Long-term capture and handling effects on body condition, reproduction and survival in a semi-aquatic mammal

In long-term individual-based field studies, several parameters need to be assessed repeatedly to fully understand the potential fitness effects on individuals. Often studies only evaluate capture stress that appears in the immediate weeks or breeding season and even long-term studies fail to evaluate the long-term effects of their capture procedures. We investigated effects of long-term repeated capture and handling of individuals in a large semi-aquatic rodent using more than 20 years of monitoring data from a beaver population in Norway. To investigate the effects, we corrected for ecological factors and analysed the importance of total capture and handling events, years of monitoring and deployment of telemetry devices on measures related to body condition, reproduction and survival of individual beavers. Body mass of dominant individuals decreased considerably with number of capture events (107 g per capture), but we found no statistically clear short or long-term effects of capture and handling on survival or other body condition indices. Annual litter size decreased with increasing number of captures among older individuals. Number of captures furthermore negatively affected reproduction in the beginning of the monitoring, but the effect decreased over the years, indicating habituation to repeated capture and handling. By assessing potential impacts on several fitness-related parameters at multiple times, we can secure the welfare of wild animal populations when planning and executing future conservation studies as well as ensure ecologically reliable research data.

30 years of large river restoration: How long do restored floodplain channels remain suitable for targeted rheophilic fishes in the lower river Rhine?

The ecological efficacy of river restoration projects may change over time, resulting in the loss of their ecological function for targeted species. The goal of this study was to evaluate the rheophilic nursery function of restored floodplain channels over time, by analysing 30 years of monitoring data from 12 restoration projects in the lower river Rhine. We hypothesised that the nursery function would change over time, caused by the combined effects of decreasing flow conditions and succession processes affecting habitat heterogeneity. We found that nursery area suitability for rheophilic fish was almost 4 times higher in two-sided connected channels than in one-sided connected channels, although the response trends of rheophilic fish were similar for both water body types. These response curves showed clear optima with channel age, for rheophilic fish abundance at 13 to 14 years post-restoration, indicating optimal nursery conditions. On the other hand, rheophilic species richness showed a steadily decreasing trend with channel age, suggesting aging channels became less suitable as nursery areas for most rheophilic fish species. The presence of permanent flow was found to be the main driving factor in explaining both rheophilic fish community trends and habitat succession in individual restored channels. We did not observe an effect of habitat heterogeneity on nursery function for rheophilic fish. To create and maintain optimal nursery conditions in restored floodplain channels of strongly anthropogenically influenced rivers such as the river Rhine, we propose a management strategy involving cyclic rejuvenation through human intervention, focusing on restoring permanent flow, with a frequency of on average every 15 years, depending on the rate of aggradation and targeted rheophilic species. We also propose a thorough investigation of the relationship between habitat heterogeneity and nursery success in floodplain channels, as a next step in the identification of suitable nursery areas for rheophilic fishes.

Long-term forest health implications of roadlessness

The 2001 Forest Service Roadless Rule prohibits roadbuilding in forests across an area equivalent to the combined states of New York and Maine (236 000 km2). There have been recent assertions that roads are needed to prevent fire and to keep forests healthy. Despite twenty years of ongoing forest health monitoring and the unique scope and ecological significance of this network of roadless areas, there has to date been no integrated assessment of the relationship between roads and forest health. Here, this question was addressed by synthesizing different sources of nationally consistent, longitudinal monitoring data. Agency management records show that a lack of roads has not stopped fire prevention measures; fuel management activities in roadless areas have actually been more numerous on a per-square kilometer basis than elsewhere in the National Forest System, although activities in areas with roads cover larger areas. Historical fire maps indicate that forests with and without roads have burned at similar rates since the Rule took effect. The apparent neutrality of roads with respect to fire occurrence may be due to higher rates of human caused ignition near roads offsetting advantages related to more agile positioning of fire-fighting assets. Beyond the fire dimension of forest health, analysis of over 15 000 inventory plots showed that while tree root disease is only weakly correlated with proximity to roads, roads are strongly associated with the spread of invasive plant species in national forests. Non-native plants are twice as common within 152 meters (500 feet) of a road as farther away. Speculation that eliminating road prohibitions would improve forest health is not supported by nearly twenty years of monitoring data.

Structural monitoring of an integral bridge in South Africa

This paper gives an overview of almost 3 years of monitoring data obtained from instrumentation installed in a 90 m long reinforced concrete integral bridge in South Africa. The main objective of this structural monitoring project was to assess the effect of environmental factors on integral bridge abutment movement, with specific focus on thermal effects. The data obtained from the instrumentation enable designers to compare real and assumed effective bridge deck temperatures, earth pressures and abutment movements. Analysis of the data seems to indicate that the deck cross-sectional shape (defined as the ratio of surface area to the cross-sectional area) has a significant effect on the effective bridge deck temperature, abutment movement and earth pressure.