A citizen data-based approach to predictive mapping of spatial variation of natural phenomena

The vast accumulation of environmental data and the rapid development of geospatial visualization and analytical techniques make it possible for scientists to solicit information from local citizens to map spatial variation of geographic phenomena. However, data provided by citizens (referred to as citizen data in this article) suffer two limitations for mapping: bias in spatial coverage and imprecision in spatial location. This article presents an approach to minimizing the impacts of these two limitations of citizen data using geospatial analysis techniques. The approach reduces location imprecision by adopting a frequency-sampling strategy to identify representative presence locations from areas over which citizens observed the geographic phenomenon. The approach compensates for the spatial bias by weighting presence locations with cumulative visibility (the frequency at which a given location can be seen by local citizens). As a case study to demonstrate the principle, this approach was applied to map the habitat suitability of the black-and-white snub-nosed monkey (Rhinopithecus bieti) in Yunnan, China. Sightings of R. bieti were elicited from local citizens using a geovisualization platform and then processed with the proposed approach to predict a habitat suitability map. Presence locations of R. bieti recorded by biologists through intensive field tracking were used to validate the predicted habitat suitability map. Validation showed that the continuous Boyce index (B_cont(0.1)) calculated on the suitability map was 0.873 (95% CI: [0.810, 0.917]), indicating that the map was highly consistent with the field-observed distribution of R. bieti. B_cont(0.1) was much lower (0.173) for the suitability map predicted based on citizen data when location imprecision was not reduced and even lower (?0.048) when there was no compensation for spatial bias. This indicates that the proposed approach effectively minimized the impacts of location imprecision and spatial bias in citizen data and therefore effectively improved the quality of mapped spatial variation using citizen data. It further implies that, with the application of geospatial analysis techniques to properly account for limitations in citizen data, valuable information embedded in such data can be extracted and used for scientific mapping.     

Patterns of diversity of the Monte Desert small mammals across multiple spatial scales

The relationship between spatial scale and biodiversity patterns is a highly debated topic in ecology. We evaluated the partition of small mammal diversity at multiple spatial scales and analyzed protected areas in order to evaluate their role of protecting biodiversity at the regional scale. Diversity of small mammals in the Monte Desert was quantified at the regional biome scale (96,000 km²) (γ) and partitioned at three spatial scales: aridity range (α₃,n = 6,16 000 km²), locality level (α₂,n = 18,2-3 ha), and habitat patch (α₁,n = 51,0.6 ha). We estimated their diversity using an additive approach with three indices (richness, Shannon-Weiner, Simpson). Diversity was higher than expected at the “between aridity range (β₃)” scale, but lower at the “within-habitat scale (α₁)”. Alpha was higher than beta diversity for most spatial scales; and at the regional scale protected areas preserved a higher biodiversity than unprotected ones. Our results are the first to partition the diversity of desert small mammals at multiple spatial scales and to support the hypotheses of an irregular scale dependence of alpha and beta diversity when increasing the spatial scales. They also highlight that a better understanding of biodiversity patterns is gained when several tools are integrated and combined at different spatial scales.     

Abundance and diversity of small mammals in response to various linear habitats in semi-arid agricultural landscapes

We investigated the influence of linear habitats, three types of hedgerows and two types of field margins, on the small mammal community within a semi-arid agricultural landscape in south-central British Columbia, Canada. We examined whether abundance, species richness, and species diversity of small mammals in tree fruit orchards differed from linear, edge habitats along orchard margins. Our five edges spanned grassy to wooded habitats. Linear habitats were intensively sampled for vascular plants in 2003 and small mammal communities from 2003 to 2007. Vegetation and total abundance of small mammal species among three types of hedgerows were similar and population changes followed those within nearby apple orchards. Species richness and diversity of small mammals, however, were significantly higher in hedgerows than orchards. Fewer mammals occupied hedgerows with high volumes of herb and shrub biomass, but richness and diversity of mammals did increase with shrub volume. All seven species of small mammals were represented in the hedgerow communities, including two species at risk: the Great Basin pocket mouse Perognathus parvus and the western harvest mouse (Reithrodontomys megalotis). Two types of field margins (orchard-sagebrush and orchard-old field) along fencerows provided habitat for P. parvus. Field margins managed for herbaceous plant species along fencerows and other such linear configurations provided habitat for R. megalotis. Linear non-crop habitats should maintain the overall small mammal community, as well as the two species at risk, within this semi-arid agricultural landscape.     

Acacia communities and species responses to soil and climate gradients in the Sudano-Sahelian zone of West Africa

Abiotic environmental factors have a major impact on the distribution and performance of plant species. In order to assess two major species–environmental relations in Sudano-Sahelian Acacia woodlands, we tested the relationship of soil and climate variables on plant diversity as well as on species responses.The indicator species values clustered in five vegetation units characterized by three to ten diagnostic species with woody species richness means varying from three to seven species per 0.09 ha. The NMS ordination explained 65% of the variation in species composition and revealed that soil properties, annual precipitations and temperature range structured the diversity of Acacia communities. Along the annual precipitations gradient, the response of Acacia polyacantha and Acacia hockii showed maxima in the wettest zone of our study area (more than 850 mm/year) whilst Acacia laeta showed a maximum response in the driest zone (below 500 mm/year). The unimodal response of A. hockii, Acacia gourmaensis and Acacia seyal to the soil available water gradient spanned their central borders, respectively from 13 to 18% (optimum 16%), 11–20% (optimum 15%) and 4–12% (optimum 7.5%).The response of Acacia communities and species to soil and climate gradients, makes them performant afforestation species in specific habitats of the Sudano-Sahelian zone.     

Human ecology,ethnobotany and traditional practices in rural populations inhabiting the Monte region: Resilience and ecological knowledge

In this study, we looked for insights on how human populations inhabiting the Monte, interact with arid environments and how they use ecological knowledge on wild plants for their subsistence. Rural communities living in the Monte region have been undergoing extreme changes in both social and ecological scenarios. Most of them are agro-pastoral societies living under precarious conditions, and whose land shows marked signs of degradation. Wild plants represent an important part of their dietary components; i.e. these resources probably act as a sustenance buffer in periods of seasonal scarcity. In the present study, we analyzed some ethno-ecological strategies undertaken by these rural communities. The ethnobotanical knowledge of greatest cultural and nutritional significance includes the use of many wild plants such as Prosopis spp., Schinus spp., Ephedra spp., Condalia and Larrea spp., among others. Since ancestral times, these xeric species have been utilized as edible, medicinal, tinctorial, fodder and fuel resources. Many rural populations not only maintain wild plant use, but they also practice cattle transhumance, a tradition which tends to reduce over-grazing, allowing for the recovery of most palatable plants. Cattle transhumance, also an ancient practice, is based on landscape patchiness use. Both practices appear to be associated with an adaptive and resilient natural resource management. We refer to resilience as the capacity to cope with disturbances and changes, prevalent features in populations inhabiting this arid region. We also explore, through a study case in Patagonia, the present use of wild edible plants, its relationship with summer-cattle-transhumance, and the most salient socio-cultural factors affecting these practices. Summer-transhumance contributes to the utilization of a greater richness and quantity of wild edible plants. This activity, which used to be a family tradition, seems to be changing given that nowadays it is mainly carried out by single family members. Wild plant gathering and summer-transhumance traditions tend to be diminishing at present, probably caused by acculturation processes and socio-economic pressures. Consequently, by abandoning these ancestral customs, a negative impact on the resilience capacity of these rural communities might be occurring. This erosion process leads to a decrease in their long-term wellbeing as well as an increase in their socio-ecological vulnerability.     

Potential habitat of Acropora spp. on Florida reefs

Elkhorn and staghorn corals (Acropora palmata, Acropora cervicornis) were listed as threatened species under the Endangered Species Act in 2005. The decline of these species beginning in the late 1970s is unprecedented given the vital role they historically played as major builders of western Atlantic and Caribbean coral reefs. The goal of this study was to create potential-habitat maps for A. palmata and A. cervicornis that would show areas in which these species currently exist, as well as areas that would be suitable for their (re)establishment, using a database of reported in situ observations and existing mapped data. Using the mapped coral reef and hardbottom classifications throughout the Florida reef tract, potential-habitat maps were generated using buffers that incorporated 95% and 99% of reported observations of colonies of Acropora spp. The potential-habitat maps were produced based on benthic substrates throughout the Florida reef tract using GIS software. Locations of 99% of A. palmata observations and 84% of A. cervicornis observations coincided with previously mapped coral reef or hardbottom habitat. These results indicate that potential habitat for A. palmata is currently well defined and that potential habitat for A. cervicornis is more variable and has a wider range than that for A. palmata. This study provides a novel method of combining datasets at various geographic spatial scales and may be used to inform the current NOAA critical habitat map. One of the most important differences between the current NOAA critical habitat map and the new potential-habitat map is observed in the southeast Florida region, where A. cervicornis appears to be thriving outside of mapped reef areas and at latitudes considered marginal for hermatypic corals. Thus, the potential habitat extends further north than the previous critical habitat - and encompasses additional habitat for A. cervicornis and potentially for A. palmata.     

Modeling habitat use of the threatened and endemic mara (Dolichotis patagonum,Rodentia, Caviidae) in agricultural landscapes of Monte Desert

Effective management of natural populations depends heavily on the capacity for understanding and predicting their habitat requirements. For endemic and threatened species like the mara (Dolichotis patagonum), this information is extremely necessary for populations survival. I investigated and constructed a mathematical habitat model for the mara, with the capacity to predict the probability of finding animals in a particular environment. In the Monte Desert, maras prefer habitats with low shrub density and high percentage of bare soil. The area used by each couple of maras was 7.73 ha and shows an aggregation pattern. Contrary to expectation, about 94% of these areas were in habitats created by human activities. Grazed, burned and crop areas seem to be prefered by maras when natural open habitat disappear. This information and the results of habitat requirements can be used to monitor the status of mara populations and predict potential population extinctions according to habitat variables.     

Parasitism and haustorium anatomy of Krameria lappacea (Dombey) Burdet & B.B. Simpson (Krameriaceae), an endangered medicinal plant from the Andean deserts

Krameria lappacea (Rhatany or Ratanhia, Krameriaceae) is an endangered, overexploited medicinal plant from the semi-deserts of Andean South America, and is destructively harvested from nature. There are published data on parasitism of Krameria from three North American species, but not on K. lappacea, the only economically important species. The present study investigates the presence or absence of hemiparasitism, host plant range and haustorium morphology/anatomy. The study was carried out at two sites in Peru, Department Arequipa, Prov. Arequipa. Hemiparasitism was confirmed, with 106 haustorical connections to 18 host plant species from 17 genera and 12 plant families observed, nearly doubling the number of host plant species known for Krameria (incl. four additional angiosperm families). Root and haustorium architecture and anatomy were found to be similar to the North American species. K. lappacea is a highly generalistic hemiparasite and host distribution and abundance are likely not limiting factors for Krameria recruitment and establishment. Due to its wide range of host plants K. lappacea likely influences the performance of the bulk of perennial species in its habitat and overcollection affects the overall vegetation. Conservation strategies and adequate management should have high priority because of the likely ecological and known economical importance of this species.     

Precipitation impacts on mule deer habitat use in the chihuahuan desert of Mexico

In arid lands, food resources and predation risk become major decision factors in mule deer habitat use. We examined variables related to these two factors that might determine mule deer (Odocoileus hemionus) habitat use in a warm desert at two spatial scales: the macro-habitat scale, which relates to home range decisions, and the micro-habitat scale, which relates to decisions made during foraging. Our prediction was that habitat use should primarily be explained by food variables and, to a lesser degree, by variables related to predation risk by pumas (Puma concolor). We mapped all deer pellet groups in 72, 1 ha quadrats in the Mapimí Biosphere Reserve and measured food and habitat variables over two years with different precipitation amounts. The area was used more intensively during the dry year. Under drier conditions, deer habitat use was explained primarily by food resource variables and secondarily by variables related with predation risk. During the wetter year, food resources became unimportant while cover and visibility explained deer habitat use. The data suggest that the tradeoffs deer are willing to make between food resources and predation risk in an arid environment are strongly affected by food resource levels, as influenced by precipitation.     

Recruiting mechanisms of Cylindropuntia leptocaulis (Cactaceae) in the Southern Chihuahuan Desert

Sexual reproduction and vegetative propagation require the establishment of morphologically diverse reproductive structures (seedlings and stem segments). This study assesses both types of Cylindropuntia leptocaulis recruitment in two microenvironments protected from herbivory (in open space and under the canopy of Larrea tridentata) and with two soil types (collected below L. tridentata canopy and from open space).An observational study revealed that sexual establishment was very limited (only 8 juveniles/ha were found), while clonal establishment was more frequent (59 juveniles/ha); both types of propagule were found only under shrub canopy.Field experiments showed that, as in other Cylindropuntia species but contrasting with findings for Opuntia species, seeds germinated and seedlings survived under nurse plants as well as in open space, but they grew faster in the former environment. Faster growth under canopy shade provides better chances of successful recruitment to later life-cycle stages. Stem segments never established in open space, requiring the shade of nurse plants. This may be due to physiological constraints imposed by their small volume. In synthesis, the results indicate that clonal propagation is the most important recruitment mechanism in C. leptocaulis populations, and that it takes places under shrub canopy.     

Conflation and aggregation of spatial data improve predictive models for species with limited habitats: A case of the threatened yellow-billed cuckoo in Arizona,USA

Riparian vegetation provides important wildlife habitat in the southwestern United States, but limited distributions and spatial complexity often leads to inaccurate representation in maps used to guide conservation. We test the use of data conflation and aggregation on multiple vegetation/land-cover maps to improve the accuracy of habitat models for the threatened western yellow-billed cuckoo (Coccyzus americanus occidentalis). We used species observations (n = 479) from a state-wide survey to develop habitat models from 1) three vegetation/land-cover maps produced at different geographic scales ranging from state to national, and 2) new aggregate maps defined by the spatial agreement of cover types, which were defined as high (agreement = all data sets), moderate (agreement ≥ 2), and low (no agreement required). Model accuracies, predicted habitat locations, and total area of predicted habitat varied considerably, illustrating the effects of input data quality on habitat predictions and resulting potential impacts on conservation planning. Habitat models based on aggregated and conflated data were more accurate and had higher model sensitivity than original vegetation/land-cover, but this accuracy came at the cost of reduced geographic extent of predicted habitat. Using the highest performing models, we assessed cuckoo habitat preference and distribution in Arizona and found that major watersheds containing high-probably habitat are fragmented by a wide swath of low-probability habitat. Focus on riparian restoration in these areas could provide more breeding habitat for the threatened cuckoo, offset potential future habitat losses in adjacent watershed, and increase regional connectivity for other threatened vertebrates that also use riparian corridors.     

Winter establishment of the alien annual Schismus barbatus is not affected by insect herbivory in Northern-Central Monte Desert

We studied the effect of ant herbivory on the establishment and survival of the annual plant Schismus barbatus. We hypothesized that ants may control this species when biomass of native plants is generally low during their vegetative period. We predicted that ant herbivory will decrease plant survival and reproduction. We tested our prediction with an insect exclosure experiment in a sandy desert of Northern-Central Monte.We found more than 12 000 established seedlings per square meter on early May, after two consecutive rain pulses of ca. 20 mm each. Overall, we found that almost 75% of recruited plants survived by the end of the cool season (September), and that 22–24% of the initially established plants survived as mature reproductive plants by the end of the growing season (December). Contrary to our expectation, insect herbivory did not affect plant establishment, plant survival or the proportion of flowering and fruiting individuals of S. barbatus.The large number of seedlings reported, the ability to exploit a temporal window free of plant competitors and enemies, and the availability of microsites where this species can succeed, all suggest that S. barbatus may have the potential to become an important plant invader in the Monte Desert.     

Patterns of alien plant invasions in northwestern Patagonia, Argentina

Invasive plant species are a growing concern in many regions of the world, yet little information is available on the effects of habitat type and distance to urban settlements on the ability of alien plants to become established. We studied plant communities from the arid steppes to the Andean forest within two national parks and surroundings, in northwestern Patagonia, Argentina. Alien and native vascular plant species were sampled using 90 × 100 m² plots and analyzed in relation to both climatic and environmental variables and distance to urban centres. We also compared life-forms of alien and native species. Precipitation and distance to an urban centre were important determinants of alien species community richness and composition, and shrubland sites had significantly more alien species than forest or steppe sites. Alien flora (15% of the species) was composed of a higher proportion of annuals and biennials than native flora. Our results suggest that precipitation, distance to source population, and anthropogenic disturbance influence the invasion process in this region, together with the availability of open niches. This work stresses the importance of monitoring invasive species in natural reserves, and of considering habitat types as well as idiosyncratic characteristics of the non-natives for developing management strategies.     

Effects of fire and environmental variables on plant structure and composition in grazed salt desert shrublands of the Great Basin (USA)

Fire in shrub-dominated portions of the Great Basin, largely fueled by non-native annuals such as Bromus tectorum, has become an important structuring force altering vegetation composition and soil characteristics. The extent to which fire affects native species in drier portions of the Great Basin, termed salt desert, is poorly documented. We conducted a survey of grazed salt desert habitat in northwestern Nevada 5 years after wildfires burned 650,000 ha, with the goal of investigating community response to fire and factors correlating with post-fire recovery. We found that recruitment of a dominant shrub, Artemisia spinescens, is severely restricted following fire: it occurred in only 2 of the 24 burned sites. The co-dominant shrub, Atriplex confertifolia, occurred in most burned sites although on average its percent cover was one-third lower than adjacent unburned sites. Biotic soil crust cover was four times lower, and non-native species cover 5 times higher, in burned sites compared to unburned. Ordination analyses confirmed differences among plant communities in burned versus unburned sites, with environmental variables soil conductivity, plant litter, soil potassium (K⁺) and pH explaining 38% of the variance in community composition. However, we found no environmental predictors of recovery for native species in burned sites. Future recruitment is likely to be further limited, as fire frequency in the salt desert is expected to increase with invasion by non-native annual grasses and with global climate change.     

Nest dynamics of Constrictotermes cyphergaster (Termitidae,Nasutitermitinae) and its association with the supporting vegetation in a semiarid area,northeast, Brazil

We evaluated growth, abandonment, decay and emergence of new nests of the Neotropical termite Constrictotermes cyphergaster (Termitidae) and its association with the supporting vegetation in an area of caatinga (arid thorn scrub in the state of Paraíba, northeastern Brazil). In an area of 1 ha, a total of 272 nests were observed monthly, from March 2005 to March 2007. Of these, 245 nests were small, 9 were of medium size, and 18 were large nests. During the rainy season (from June to February), nests grew 94.2 L, whereas during the dry season (March–May), their total growth was 23 L. The number of abandoned nests was positively correlated with rainfall. Decomposition of nests was greater during the rainy season. The pattern of nest distribution was associated with the distribution of the primary supporting plants. Rainfall appears to be one of the most important factors in the dynamics of growth of nests of C. cyphergaster in the caatinga.     

Cladocera as indicators of trophic state in Irish lakes

We examined the impact of lake trophic state on the taxonomic and functional structure of cladoceran communities and the role of nutrient loading in structuring both cladoceran and diatom communities. Surface sediment assemblages from 33 Irish lakes were analysed along a gradient of total phosphorus concentration (TP; 4.0–142.3 μg l⁻¹), using a variety of statistical approaches including ordination, calibration and variance partitioning. Ordination showed that the taxonomic structure of the cladoceran community displayed the strongest response to changes in lake trophic state, among 17 measured environmental variables. Trophic state variables chlorophyll-a and TP explained about 20% of the variance in both cladoceran and diatom assemblages from a set of 31 lakes. Procrustes analysis also showed significant concordance in the structure of cladoceran and diatom communities (P < 0.001). Thus, lake trophic state affects the taxonomic structure of both primary and secondary producers in our study lakes. We also found a significant decrease in relative abundance of taxa associated with both macrophytes and sediments, or sediments only, along the TP gradient (r = −0.49, P = 0.006, n = 30), as well as an increase in the proportion of the planktonic group (r = 0.43, P = 0.017, n = 30). This suggests that cladoceran community structure may also be shaped by lake trophic state indirectly, by affecting habitat properties. We found no relationship between lake trophic state and the relative abundance of each of three cladoceran groups that display different body size. We compared community structure between bottom and top sediment samples in cores from six Irish lakes. Results revealed similar trajectories of nutrient enrichment over time, as well as a strong shift in cladoceran functional structure in most systems. This study confirms that Cladocera remains in lake sediments are reliable indicators of lake trophic state. This study also highlights the fact that taxonomic and functional structure should both be considered to account for the multiple factors that shape cladoceran communities.     

The relation between accessibility,diversity and indigenous valuation of vegetation in the Bolivian Andes

A quantitative ethnobotanical study was conducted in the semi-arid Bolivian Andes community of Apillapampa to evaluate the impact of site accessibility on the diversity and perceived usefulness of (sub-)woody plants. Vegetation was sampled in thirty-six transects of 50 × 2 m², whereas data on plant uses were obtained from 13 local Quechua participants. Accessibility of sample sites correlated negatively with plant diversity, but positively with perceived usefulness. Hence, in spite of being less diverse, vegetation of more accessible sites was perceived as more useful to people than vegetation of more remote and also more diverse sites. This result contributes to the validity of the widely accepted notion that “more accessible plant resources are more useful to people”, not only at the level of individual plant species, but also for entire vegetation communities. In this respect, our finding that people attribute an equal usefulness to the vegetation of two local ecological zones (i.e. prepuna and puna) most likely reflects their similar accessibility from the village centre, which is located on the edge between both zones.     

Effects of sample size on the accuracy of geomorphological models

Commonly, the most costly part of geomorphological distribution modelling studies is gathering the data. Thus, guidance for researchers concerning the quantity of field data needed would be extremely practical. This paper scrutinises the relationship between the sample size (the number of observations varied from 20 to 600) and the predictive ability of the generalized linear model (GLM), generalized additive model (GAM), generalized boosting method (GBM) and artificial neural network (ANN) in two data settings, i.e., independent and split-sample approaches. The study was performed using empirical data of periglacial processes from an area of 600 km² in northernmost Finland at grid resolutions of 1 ha (100 × 100 m) and 25 ha (500 × 500 m). A rather sharp increase in the predictive ability of the models was observed when the number of observations increased from 20 to 100, and the level of robust predictions was reached with 200 observations. The result indicates that no more than a few hundred observations are needed in geomorphological distribution modelling at a medium scale resolution (ca. 0.01–1 km²).     

Comparison of traditional wild plant knowledge between aboriginal communities inhabiting arid and forest environments in Patagonia, Argentina

The Mapuche people have a deeply rooted tradition of wild plant use for their subsistence. In this study we evaluated whether plant selection by the Mapuche is influenced by environmental constraints. Selection patterns of wild plant richness were compared in two Mapuche communities sharing the same traditions and beliefs but inhabiting different environments. Similarities and differences in the use patterns of wild medicinal and edible plants were quantitatively analyzed by using concepts derived from ecological theory. The Cayulef community is settled in the NW Patagonian (herbaceous) steppe while the Curruhuinca community is established near the Andean temperate forest, 100 km away from each other. Free-listing and semi-structured interviews were conducted with 32 families in Cayulef and 39 in Curruhuinca corresponding to 80% and 40% of each population, respectively. Data were analyzed by means of the Jaccard similarity index and statistical tests. The main results of this study showed that the home environment is a determinant factor that influences which plant species are utilized, as is the anthropic environment (with its high exotic species richness) in each community. However, similar patterns were found with respect to plant families, ways of utilization, plant parts and life forms utilized irrespective of where the communities are settled. In addition, in both populations, wild plant richness was significantly higher for medicinal than for edible species. Our results showed that the use of wild plants is primarily based on the utilization of species belonging to the nearest ecological environments that have both therapeutic and dietary functions.