Topic Independent Identification of Agreement and Disagreement in Social Media Dialogue

Research on the structure of dialogue has been hampered for years because large dialogue corpora have not been available. This has impacted the dialogue research community's ability to develop better theories, as well as good off the shelf tools for dialogue processing. Happily, an increasing amount of information and opinion exchange occur in natural dialogue in online forums, where people share their opinions about a vast range of topics. In particular we are interested in rejection in dialogue, also called disagreement and denial, where the size of available dialogue corpora, for the first time, offers an opportunity to empirically test theoretical accounts of the expression and inference of rejection in dialogue. In this paper, we test whether topic-independent features motivated by theoretical predictions can be used to recognize rejection in online forums in a topic independent way. Our results show that our theoretically motivated features achieve 66% accuracy, an improvement over a unigram baseline of an absolute 6%.Comment: @inproceedings{Misra2013TopicII, title={Topic Independent Identification of Agreement and Disagreement in Social Media Dialogue}, author={Amita Misra and Marilyn A. Walker}, booktitle={SIGDIAL Conference}, year={2013}

Bird tolerance to humans in open tropical ecosystems

AbstractAnimal tolerance towards humans can be a key factor facilitating wildlife–human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene.</jats:p

Modelling of the response of sable antelope (Hippotragus niger niger) to trophy hunting: A GIS and remote sensing approach

RP-PCP grant/Project ECO#3,The main objective of this study was to test the impact of hunting on sable (Hippotragus niger niger) habitat selection using a combination of satellite remotely sensed data and GIS based spatial analysis. Firstly, we used remotely sensed vegetation cover estimated by the normalised difference vegetation index (NDVI) to test whether hunted sables selected more closed woodland habitats, i.e., an uncharacteristic habitat for sable, while those not exposed to hunting selected more open woodland habitats, i.e., characteristic habitat for sable. Secondly, we tested whether terrain based visibility modelled from remotely sensed data explains sable Flight Initiation Distance (FID), an indicator of fearfulness in hunted animal species, better than vegetation based visibility measured in the field. We tested these hypotheses in a study area consisting of one hunting area and one non-hunting area of northwestern Zimbabwe. Our results show that hunted sables significantly (P < 0.05) selected more closed woodland than those not exposed to hunting. Our results also show that remotely sensed Advanced Spaceborne Thermal Emission and Reflection Radiometer Digital Elevation Model (ASTER DEM) derived visibility could explain FID of sable better than field measured vegetation based visibility. Results of this thesis open new ground in spatial ecological understanding of wildlife species such as the threatened sable antelope,Ministère Français des Affaires Etrangères through the French Embassy in Zimbabwe (RP-PCP grant/Project ECO#3

An Ecological Paradox: The African Wild Dog (Lycaon Pictus) Is Not Attracted to Water Points When Water Is Scarce in Hwange National Park, Zimbabwe.

In dry biomes, spatio-temporal variation in surface water resource stocks is pervasive, with unknown effects on the ranging behaviour of large predators. This study assessed the effect of spatial variation in surface water resources on the ranging behaviour of the African wild dog (Lycaon pictus). We analyzed data for 1992 (dry year with 20 water points) and 2000 (wet year with 30 water points) against presence-only data for five packs of L. pictus in a part of Hwange National Park and adjacent smallholder communal farming areas in western Zimbabwe. Modelling the potential habitat for L. pictus using Maxent with distance from water points (Dw) and Normalized Difference Vegetation Index (NDVI) as predictor variables was successful for 2000 (AUC = 0.793) but not successful for 1992 (AUC = 0.423), with L. pictus probability of occurrence near water points being more for year 2000 than for year 1992. The predicted L. pictus range was wider in 1992 (~13888.1 km2) than in 2000 (~958.4 km2) (Test of Proportions, χ2 = 124.52, df = 1, P = 0.00). Using the 2nd order Multitype Nearest Neighbour Distance Function (Gcross), we also observed significant attraction between L. pictus and water points within only ~1km radius for 1992 but up to ~8km radius for 2000. Our study reinforced the notion that surface water resources attract wild dogs in the savannahs but paradoxically less so when water resources are scarce. In particular, our study furthers current understanding of the effects of changing water availability regimes on the endangered L. pictus, providing evidence that the endangered predator's home range encroaches into potential ecological traps (i.e., smallholder communal farming areas) when water resources are scarce

Elephant (Loxodonta africana) GPS collar data show multiple peaks of occurrence farther from water sources

The understanding of animal distribution in habitats located farther from water sources has not been dealt with adequately in the literature, yet this knowledge enables better prediction of species occurrence across an entire landscape. We tested whether elephant occurrence peaks away from water in addition to the known peak that is associated with water sources. We used the Maximum Entropy Modelling (MaxEnt) algorithm to predict the potential distribution of elephants in the Gonarezhou National Park, Zimbabwe. Elephant tracking data from Global Positioning System (GPS) collars were used as the response variable while NDVI (a proxy for forage quantity) and water sources data were the environmental variables. Results showed multiple peaks of elephant occurrence with increasing distance from water sources. Additionally, results illustrated that the peaks occur in high NDVI areas. Our findings emphasise the utility of GIS and remote sensing in enhancing our understanding of animal occurrence driven by water sources

Multiple GPS fix intervals show variations in the manner African White-backed Vultures Gyps africanus utilise space

Application of spatial data is becoming increasingly important as a tool for mapping and understanding space utilisation patterns especially for&nbsp; critically endangered species. In this study, we tested how variation in the GPS fix interval may influence space utilisation patterns by African White-backed Vultures in Hwange National Park and the surrounding areas. In order to test our objectives, we collected data from six African White-backed Vultures using solar powered GPS-GSM units. The data were collected for periods ranging from five months to nineteen months (28 June 2016 to 30 January 2018), resulting in 89 809 total GPS fixes. We tested whether home range and core areas estimated at different fix interval differ significantly. We also tested whether African White-backed Vultures show significant site fidelity and at what sampling frequency the estimated home ranges tend to reach an asymptote. We used total individual data and seasonal data to test these hypotheses. In order to estimate home range size at different fix intervals, we used the Brownian Bridge Movement Model, because unlike other traditional estimators, it explicitly&nbsp;&nbsp; incorporates temporal sequence in GPS fixes, accounts for autocorrelation in movement data, as well as missing GPS data. Home range estimates differed significantly at different GPS fix intervals. Home range and core areas for five vultures were concentrated within conservation areas. African White-backed Vultures also showed significant site fidelity across seasons except for vulture three, which demonstrated nomadic tendencies.&nbsp; Results on home range asymptote were not conclusive, because of unique individual vulture space use patterns at different fix intervals. Our study was the first to track and monitor space utilisation patterns by mature African White-backed Vultures in the Hwange ecosystem. Accordingly, our&nbsp; results have critical conservation implications for the wide-ranging, critically endangered species. French title: L’intervalle entre plusieurs points GPS montre des variations dans la manière chez le vautour africain Gyps africanus d’utiliser l’espace L’application des données spatiales devient de plus en plus importante en tant qu’outil de cartographie et de compréhension des modèles d’utilisation de l’espace, en particulier pour les espèces en danger critique d’extinction. Dans cette étude, nous avons testé comment la variation de l’intervalle de fixation GPS peut influencer les schémas d’utilisation de l’espace par les vautours africains dans le parc national du Hwange et les&nbsp; zones environnantes. Pour tester nos objectifs, nous avons recueilli des données auprès de six vautours africains à l’aide d’appareils GPS-GSM fonctionnant à l’énergie solaire. Les données ont été recueillies sur des périodes allant de cinq à dix-neuf mois (du 28 juin 2016 au 30 janvier 2018), ce qui a permis d’obtenir 89 809 positions GPS au total. Nous avons vérifié si le domaine vital et les zones centrales estimées à différents intervalles&nbsp; de fixation diffèrent de manière significative. Nous avons également testé si le vautour africain montre une fidélité significative au site et à quelle fréquence d’échantillonnage les domaines vitaux estimés ont tendance à atteindre une asymptote. Nous avons utilisé les données individuelles totales et les données saisonnières pour tester ces hypothèses. Pour estimer la taille du domaine vital à différents intervalles de points fixes, nous avons utilisé le modèle de mouvement du pont brownien car, contrairement aux autres estimateurs traditionnels, il incorpore explicitement une séquence temporelle dans les points fixes GPS, tient compte de l’autocorrélation dans les données de mouvement ainsi que des données GPS manquantes. Les estimations de la distance parcourue par le domicile diffèrent sensiblement selon les intervalles de temps entre les points GPS. Le domaine vital et les zones centrales pour cinq vautours ont été concentrés dans des zones de conservation. Les vautours africains ont également montré une fidélité significative au site au fil des saisons, à l’exception du vautour trois qui a montré des tendances nomades. Les résultats sur l’asymptote du domaine vital n’ont pas été concluants en raison des modes d’utilisation de l’espace propres à chaque vautour à différents&nbsp; intervalles de temps. Notre étude est l’une des premières à suivre et à surveiller les schémas d’utilisation de l’espace par les vautours africains adultes dans l’écosystème du Hwange. Nos résultats ont donc des implications cruciales pour la conservation de cette espèce à large distribution etgravement menacée

Effects of Fire Frequency on Woody Plant Composition and Functional Traits in a Wet Savanna Ecosystem

The objective of this study was to assess the effect of fire frequency on vegetation taxonomic and functional diversity in a wet savanna ecosystem, eastern Zimbabwe. The study area was stratified into three fire frequency regimes using a 15-year fire history (2000–2014) across the landscape: high (HFF: burnt every 1-2 years), medium (MFF: burnt every 3-4 years), and low (LFF: burnt every 5-6 years). Data were collected from a total of 30 plots measuring 20 m × 20 m each between March and May 2018. In each plot, we recorded tree maximum height (Hmax), woody plant density, basal diameter, resprouting capacity, and bark thickness. We calculated species evenness, diversity, functional richness (FRic), Rao’s Quadratic Entropy (RaoQ), functional redundancy, and relative bark thickness. We recorded 1,031 individual trees belonging to 24 species across the three fire regimes. Significant differences across the three fire regimes were recorded for Hmax, woody plant density, and relative bark thickness P0.05. Species like Cassia petersiana, Cussonia spicata, Vachellia spp., and Rhus lancea were associated with LFF, while species like Protea gaguedi, Brachystegia utilis, and Vangueria infausta showed a strong association with HFF to MFF. Our study demonstrated that a combination of taxonomic and functional diversity metrics is adequate to evaluate the response of savanna vegetation to fire. We recommend a further assessment on vegetation composition using other elements of fire regimes

Exploring the utility of Sentinel-2 MSI and Landsat 8 OLI in burned area mapping for a heterogenous savannah landscape.

When wildfires are controlled, they are integral to the existence of savannah ecosystems and play an intrinsic role in maintaining their structure and function. Ample studies on wildfire detection and severity mapping are available but what remains a challenge is the accurate mapping of burnt areas in heterogenous landscapes. In this study, we tested which spectral bands contributed most to burnt area detection when using Sentinel-2 and Landsat 8 multispectral sensors in two study sites. Post-fire Sentinel 2A and Landsat 8 images were classified using the Random Forest (RF) classifier. We found out that, the NIR, Red, Red-edge and Blue spectral bands contributed most to burned area detection when using Landsat 8 and Sentinel 2A. We found out that, Landsat 8 had a higher classification accuracy (OA = 0.92, Kappa = 0.85 and TSS = 0.84)) in study site 1 as compared to Sentinel-2 (OA = 0.86, Kappa = 0.74 and TSS = 0.76). In study site 2, Sentinel-2 had a slightly higher classification accuracy (OA = 0.89, Kappa = 0.67 and TSS = 0.64) which was comparable to that of Landsat 8 (OA = 0.85, Kappa = 0.50 and TSS = 0.41). Our study adds rudimentary knowledge on the most reliable sensor allowing reliable estimation of burnt areas and improved post-fire ecological evaluations on ecosystem damage and carbon emission

Location of the study system comprising of part of the Hwange National Park and adjacent communal smallholder farming areas in Zimbabwe

<p>Location of the study system comprising of part of the Hwange National Park and adjacent communal smallholder farming areas in Zimbabwe</p