Anthropic Land Research Articles

Reptile Diversity Patterns Under Climate and Land Use Change Scenarios in a Subtropical Montane Landscape in Mexico

ABSTRACTAimMountainous regions are rich in reptile biodiversity but face threats from climate and land use changes. Understanding how these factors affect reptile diversity in these regions can highlight key conservation hotspots that require effective conservation actions. Here, we explored reptile taxonomic and functional diversity patterns along the Sierra Madre del Sur region in southeast Mexico, and potential changes in future years caused by different climate and land use change scenarios.LocationSierra Madre del Sur, México.TaxonReptiles.MethodsWe used species distribution models and information on species traits to estimate taxonomic and functional diversity throughout the Sierra Madre del Sur (SMS) region under current and future climate and land use change scenarios.ResultsGreater taxonomic and functional diversity was observed in both temperate and tropical forests. Taxonomic diversity was higher in more drier areas at high elevations while higher functional diversity was observed in wetter areas at intermediate‐to‐high elevations. Lower diversity for both dimensions was associated with anthropic land uses. In future scenarios, both dimensions of diversity are expected to increase in temperate forest in highlands of central Oaxaca and decrease in the southcentral portion of the SMS, particularly for the worst scenarios due to increased deforestation rates.Main ConclusionsHigher taxonomic diversity in more drier areas at high elevations could be due to historical and evolutionary factors, while higher functional diversity in wetter areas at intermediate‐to‐high elevations may be explained by a higher environmental heterogeneity in forests within these conditions. Larger diversity losses in the southcentral portion of the SMS are probably due to larger predicted deforestation rates in those areas. Our results are valuable not just for informing conservation actions, such as the creation of protected natural areas but also to understand the underlying processes behind the patterns of reptile diversity.

Combining roadkill hotspots and landscape features to guide mitigation measures on highways

Identifying highway sections with high vertebrate roadkill and associated landscape features is crucial for proposing mitigation measures to reduce the negative impacts of wildlife-vehicle collisions on biodiversity, human safety, and the economy. Focusing on highways in the State of Mato Grosso do Sul, Brazil, this study proposes a prioritization of road segments for implementing mitigation measures based on landscape characteristics and roadkill hotspots recorded between 2016 and 2018. Roadkills distribution was assessed using Hotspot Identification, detecting sections with the highest collision intensity. The effect of landscape variables, such as the area and distance of natural vegetation and anthropic land use within 1 km of the highways, on roadkill was modelled using General Linear Mixed Models, which were evaluated based on two response variables: (1) roadkill presence/absence and (2) roadkill abundance, with model selection by the Akaike information criterion. Based on roadkill hotspot identification analysis and predictive models of the influence of landscape elements on roadkill occurrence and abundance, an evaluation criterion was proposed to determine the priority sites for installing wildlife crossings, speed bumps, and signposts. Wildlife-vehicle collisions were positively associated with riparian vegetation areas and urban areas, while negatively associated with silviculture and distance to “cerradão” (forest Cerrado) patches. Eleven road sections were identified as top priority, two as high priority and 78 as medium priority for the installation of mitigation measures with varying cost-benefit ratios. Our results can potentially guide decision-making at broader scales and provide mitigating alternatives applicable to dry ecosystems such as the Cerrado (Brazilian Savanna).

Microbial, chemical, and isotopic monitoring integrated approach to assess potential leachate contamination of groundwater in a karstic aquifer (Apulia, Italy)

Landfill sites are subjected to long-term risks of accidental spill of leachate through the soil and consequential contamination of the groundwater. Wide areas surrounding the landfill can seriously be threatened with possible consequences to human health and the environment. Given the potential impact of different coexisting anthropic pollution sources (i.e., agriculture and cattle farming) on the same site, the perturbation of the groundwater quality may be due to multiple factors. Therefore, it is a challenging issue to correctly establish the pollution source of an aquifer where the landfill is not isolated from other anthropic land uses, especially in the case of a karstic coastal aquifer. The present study is aimed at setting in place an integrated environmental monitoring system that included microbiological, chemical, and isotope methods to evaluate potential groundwater pollution in a landfill district in the south of Italy located in Murgia karstic aquifer. Conventional (microbial plate count and physical–chemical analyses) and advanced methods (PCR-ARISA, isotope analysis of δ18O, δ2H, 3H, δ 13C, δ 15N-NO3−, and δ 18O-NO3−) were included in the study. Through data integration, it was possible to reconstruct a scenario in which agriculture and other human activities along with seawater intrusion in the karst aquifer were the main drivers of groundwater pollution at the monitored site. The microbiological, chemical, and isotope results confirmed the absence of leachate effects on groundwater quality, showing the decisive role of fertilizers as potential nitrate sources. The next goal will be to extend long-term integrated monitoring to other landfill districts, with different geological and hydrogeological characteristics and including different sources of pollution, to support the ecological restoration of landfills.

Predicting bird diversity through acoustic indices within the Atlantic Forest biodiversity hotspot

The increasing conversion of natural areas for anthropic land use has been a major cause of habitat loss, destabilizing ecosystems and leading to a biodiversity crisis. Passive acoustic sensors open the possibility of remotely sensing fauna on large spatial and temporal scales, improving our understanding of the current state of biodiversity and the effects of human influences. Acoustic indices have been widely used and tested in recent years, with an aim towards understanding the relationship between indices and the acoustic activity of several taxa in different types of environments. However, studies have shown divergent relationships between acoustic indices and the vocal activity of most soniferous taxa. A combination of indices has, in turn, been reported as a promising tool for representing biodiversity in different contexts. We used uni- and bivariate models to test different combinations of 8 common indices in relation to bird assemblage metrics. We recorded twenty-two study sites in Brazil’s Atlantic Forest and three different types of environments in each site (forest, pasture, and swamp). Our results showed that 1) the best acoustic indices for explaining bird richness, abundance, and diversity were Bioacoustic and Acoustic Complexity; 2) the type of environment (forest, pasture, and swamp) influenced the performance of acoustic indices in explaining bird biodiversity, with the highest score model (biggest R2 value) being a combination between Acoustic Diversity and Bioacoustic indices. Our results do support the use of acoustic indices in monitoring the acoustic activity of birds, but combining indices is encouraged since it provided the best results. However, given the divergence we found across environments, we recommend that sets of indices are tested to determine which of them best describe the biodiversity pattern models for a specific habitat. Based on our results, we propose that biodiversity patterns can be predicted through acoustic patterns. However, the level of confidence will depend on the acoustic index used and on focal taxa of interest (i.e., birds, amphibians, insects, and mammals).

Malaria Risk Drivers in the Brazilian Amazon: Land Use-Land Cover Interactions and Biological Diversity.

Malaria is a prevalent disease in several tropical and subtropical regions, including Brazil, where it remains a significant public health concern. Even though there have been substantial efforts to decrease the number of cases, the reoccurrence of epidemics in regions that have been free of cases for many years presents a significant challenge. Due to the multifaceted factors that influence the spread of malaria, influencing malaria risk factors were analyzed through regional outbreak cluster analysis and spatio-temporal models in the Brazilian Amazon, incorporating climate, land use/cover interactions, species richness, and number of endemic birds and amphibians. Results showed that high amphibian and bird richness and endemism correlated with a reduction in malaria risk. The presence of forest had a risk-increasing effect, but it depended on its juxtaposition with anthropic land uses. Biodiversity and landscape composition, rather than forest formation presence alone, modulated malaria risk in the period. Areas with low endemic species diversity and high human activity, predominantly anthropogenic landscapes, posed high malaria risk. This study underscores the importance of considering the broader ecological context in malaria control efforts.

Diversity of spiders (Araneae) in the anthropic land covers of Davao City, Philippines

Diversity of spiders (Araneae) in the anthropic land covers of Davao City, Philippines

Soil type determines the magnitude of soil fertility changes by forest-to-pasture conversion in Western Amazonia

The deforestation of tropical forests raises environmental concerns worldwide. Removing the pristine forest impacts the soil, consequently affecting the environmental services it provides. Within this context, the main goal of this study was to determine how the conversion of the tropical rainforest to pasture affects soil fertility across an extended range of soil heterogeneity, including different soil types. We sampled 13 sites, among forests, recent pastures (≤7-year-old), and old pastures (≥10-year-old), on Acrisols, Ferralsols, Plinthosols, and Luvisols, across a ± 800 km geographical range in the Western Brazilian Amazon. Soils were classified taxonomically, and their superficial layer's chemical and physical properties (0–10 cm) were analyzed. Furthermore, we tested the sensibility of Actinobacteria and Proteobacteria to detect changes in these soil properties based on their ecological habitat. An inter-regional gradient of soil fertility was observed, and the sampling sites were clustered mostly by soil type and associated land use than by spatial distance. The Sum of bases, Ca + Mg, base saturation, Al saturation, and pH were consistently affected by land use, increasing after conversion to pasture, at different degrees and with a more pronounced effect on oxidic soils. The Sum of bases was the only property that increased significantly among the study sites (Radj = 0.860, p < 0.001), being able to detect the effect of anthropic land use on a larger coverage of soil types. Finally, the Actinobacteria:Proteobacteria ratio was also sensitive to the impact of forest-to-pasture conversion, with a higher ratio observed in pasture systems, and it was positively correlated with soil pH (rho = 0.469, p < 0.001). Our results consistently show that the forest-to-pasture conversion leads to strong alterations in the soil environment, with varying intensities depending on soil type.

Ecological integrity assessment of streams in the light of natural ecoregions and anthropic land use.

Reference conditions for river bioassessment should be established inside ecoregions. Our objectives were (1) to implement a bioassessment methodology for Uruguayan prairie streams regarding ecoregions and land use and (2) to assess the ecological integrity of streams of the Río Negro basin in Uruguay. Due to logistical constraints, sampling was divided into two collection trips: one including the upper basin in fall 2015 and the other including the lower basin in spring 2016. Basins were analyzed separately due to seasonal and geographical differences. In the streams sampled in fall 2015, conductivity, total nitrogen (TN), and total phosphorus (TP) were higher in sedimentary ecoregions than in crystalline ones, independent on land use. In those sampled in spring 2016, these variables showed the highest values in the ecoregions dominated by agriculture. Eighty percent of the sampled streams presented the impact of cattle in their riparian zone. Discriminant analysis showed a similar composition of macroinvertebrates among ecoregions in 2015, but different composition between land uses. Conversely, in 2016, there were differences among some ecoregions, but not between land uses. Agriculture was correlated with tolerant invertebrates, while natural land use and afforestation were correlated with sensitive ones. The BMWP-Colombia showed the impact of livestock on streams, but in general good water quality, while an index of genera for Uruguay, indicated that all streams are eutrophic, thereby confirming the importance of using different types of metrics. Due to its geographical homogeneity and small size, a smaller number of ecoregions could be defined for stream assessments in the Río Negro basin.

RESPONSE OF TAXONOMIC AND FUNCTIONAL BENTHIC MACROFAUNA RICHNESS TO LAND USE AND LAND COVER AT BRAZILIAN RESERVOIRS DURING EXTREME DROUGHT

Introduction: Reservoirs are artificial aquatic ecosystems created by damming rivers, and are influenced by different sorts of impacts. Anthropic land use and occupation are one of the main causes of the loss of environmental quality and biological diversity in aquatic ecosystems. The objective of this work was to evaluate the effects of land use and occupation on the taxonomic and functional richness of benthic macroinvertebrates in reservoirs in the Brazilian semiarid region during a period of extreme drought. Material and methods: The study was conducted in six reservoirs located in the semiarid region from Brazilian Northeast (Paraíba and Rio Grande do Norte states): Sabugí, Passagem das Traíras, Cruzeta, Cordeiro, Sumé and Poções. The collections of benthic macrofauna, physical and chemical variables of water and the mapping of land use and occupation were performed for the years 2014 and 2019, in June and September. The sampling period was characterized as the most severe drought in the last 50 years in this study area. The land use and occupation were verified through the semi-supervised classification method of images captured by the Landsat 8 satellite, within 100 meters of the reservoir margin. The diversity of benthic macrofauna was analyzed through the taxonomic richness and functional richness, according to five functional characteristics: feeding trophic groups, breathing mode, voltinism, body size and body protection. To check for significant differences in physical and chemical water variables and taxonomic and functional richness among land use and land cover categories we performed PERMANOVA test. Results and Discussion: Seven land use and land cover categories were found in the reservoirs studied in the years 2014 and 2019, these are: water, agriculture, pasture, exposed soil, human occupation, open vegetation (native and exotic species of small/medium size with continuous spacing) and tree/shrub vegetation (native and exotic species of medium/large size with associated herbaceous stratum and predominance of semi-continuous dorsel). In all reservoirs the prevalent-use was pasture. Physical and chemical variables of water varied significantly among land use and land cover types, they were soluble reactive phosphate (p=0.02), total phosphorus (p=0.002) and water volume (p=0.01). The highest concentrations of total phosphorus were associated with predominant human occupation and soluble reactive phosphate with agriculture. The highest percentage of water volume was associated with a predominant use of tree/shrub vegetation. In reservoirs of semiarid regions with low connectivity due to intermittent rivers and extreme drought periods, adjacent anthropic activities such as agriculture, pasture and human occupation are the main external sources of nutrients. The taxonomic and functional richness of benthic macrofauna was higher in areas of open vegetation, however, it did not vary significantly between land use and land cover categories. Conclusions: Our results show that the effects of anthropic use and occupation in reservoirs associated with water scarcity lead to the homogenization of the macrobenthic community, which can generate negative consequences in processes sustained by the community.

Conservation opportunities and challenges in Brazil's roadless and railroad-less areas.

Policy and legislation rarely acknowledge the importance of keeping intact ecosystems road- and railroad-free. By modeling Brazil’s remaining roadless and railroad-less (RLRL) areas, we found that, although they hold the vast majority of the country’s remaining native vegetation (81.5%), because of their limited protection status, only 38% of Brazil’s remaining native vegetation is both protected and in RLRL areas. Current federal policy aims to develop transportation infrastructure designed with antiquated planning methods that threaten remaining intact ecosystems, while concurrently weakening the country’s hallmark environmental protections and commitments. Where Brazil builds its new roads and railroads matters for conservation planning. The occurrence of native vegetation and anthropic land use is associated, at varying degrees, to transportation infrastructure throughout most of Brazil. We highlight that by pursuing conservation opportunities in RLRL areas, Brazil could instead make impactful steps for conservation, restoration planning, and tangible progress toward achieving national and international environmental and conservation commitments.

Evolutions of 30-Year Spatio-Temporal Distribution and Influencing Factors of Suaeda salsa in Bohai Bay, China

Suaeda salsa (L.) Pall. (S. salsa) acts as a pioneer species in coastal wetlands due to its high salt tolerance. It has significant biodiversity maintenance, socioeconomic values (e.g., tourism) due to its vibrant color, and carbon sequestration (blue carbon). Bohai Bay region, the mainly distributed area of S. salsa, is an economic intensive region with the largest economic aggregate and population in northern China. The coastal wetland is one of the most vulnerable ecosystems with the urbanization and economic developments. S. salsa in Bohai Bay has been changed significantly due to several threats to its habitat in past decades. In this paper, we analyzed all available archived Landsat TM/ETM+/OLI images of the Bohai Bay region by using a decision tree algorithm method based on the Google Earth Engine (GEE) platform to generate annual maps of S. salsa from 1990 to 2020 at a 30-m spatial resolution. The temporal-spatial dynamic changes in S. salsa were studied by landscape metric analysis. The influencing factors of S. salsa changes were analyzed based on principal component analysis (PCA) and a logistic regression model (LRM). The results showed that S. salsa was mainly distributed in three regions: the Liao River Delta (Liaoning Province), Yellow River Delta (Shandong Province), and Hai River Estuary (Hebei Province, Tianjin). During the past 31 years, the total area of S. salsa has dramatically decreased from 692.93 km2 to 51.04 km2, which means that 92.63% of the area of S. salsa in the Bohai Bay region was lost. In the 641.89 km2 area of S. salsa that was lost, 348.80 km2 of this area was converted to other anthropic land use categories, while 293.09 km2 was degraded to bare land. The landscape fragmentation of S. salsa has gradually intensified since 1990. National Nature Reserves have played an important role in the restoration of suitable S. salsa habitats. The analysis results for the natural influencing factors indicated that precipitation, temperature, elevation, and distance to the coastline were considered to be the major influencing factors for S. salsa changes. The results are valuable for monitoring the dynamic changes of S. salsa and can be used as effective factors for the restoration of S. salsa in coastal wetlands.

Distribution extension and first verified records for Narrow-bridged&nbsp;Musk Turtle, Claudius angustatus Cope, 1865 (Testudines, Kinosternidae) in the Selva Lacandona, Mexico

We document the first verifiable records of Claudius angustatus Cope, 1865 in the Selva Lacandona, Chiapas, Mexico. Three individuals were observed in different types of anthropic land covers. These records are the most recent observations of C. angustatus in the southeastern zone of its range in more than 20 years, thus representing the southernmost known occurrences of this species. With these records we confirm the long-suspected presence of C. angustatus in the region, increasing the number of reptile species in the Selva Lacandona to 91.

Toward Best Management Practices for Ecological Corridors

Ecological corridors are one of the best, and possibly only viable, management tools to maintain biodiversity at large scales and to allow species, and ecological processes, to track climate change. This document has been assembled as a summary of the best available information about managing these systems. Our aim with this paper is to provide managers with a convenient guidance document and tool to assist in applying scientific management principles to management of corridors. We do not cover issues related to corridor design or political buy in, but focus on how a corridor should be managed once it has been established. The first part of our paper outlines the history and value of ecological corridors. We next describe our methodologies for developing this guidance document. We then summarize the information about the impacts of linear features on corridors and strategies for dealing with them—specifically, we focus on the effects of roads, canals, security fences, and transmission lines. Following the description of effects, we provide a summary of the best practices for managing the impacts of linear barriers. Globally, many corridors are established in the flood plains of stream and rivers and occur in riparian areas associated with surface waters. Therefore, we next provide guidance on how to manage corridors that occur in riparian areas. We then segue into corridors and the urban/suburban environment, and summarize strategies for dealing with urban development within corridors. The final major anthropic land use that may affect corridor management is cultivation and grazing agriculture. We end this review by identifying gaps in knowledge pertaining to how best to manage corridors.

Hydrological intermittency drives diversity decline and functional homogenization in benthic diatom communities

Over the last decades, the combined effects of global climate changes and severe land use modifications have been exacerbating river hydrological alterations and habitat fragmentation in many Mediterranean rivers. This trend is predicted to intensify, with expected significant impacts on taxonomic and functional diversity of benthic communities in the next future.By comparing perennial and intermittent reaches, the present research aims at investigating the role of flow intermittency, driven by the combined effects of climatic variables and land use changes, on benthic diatom communities in Mediterranean streams (NW Italy), by analysing data collected over 11 years. In order to avoid potential confounding effects related to water quality, sites characterized by “poor” or “bad” water quality were excluded a priori.We observed significant differences between permanent and intermittent sections in terms of both climatic variables and land use: higher temperatures and lower precipitations, coupled with an extensive anthropic land use, intensify the natural flow intermittency in intermittent sites. This led to a significant decline in diatom species diversity, at both local and regional scales, and to changes to life history traits. In particular, communities of intermittent reaches were taxonomically and functionally different and less heterogeneous than assemblages characterizing perennial ones, showing higher percentages of small, mainly stalked and pioneer taxa belonging to the low profile guild. Conversely taxa colonizing permanent reaches were bigger, belonging to the high profile guild and able to produce colonies, thus indicating high environmental stability.Our results highlighted how hydrological alterations are profoundly threatening Mediterranean streams and the diatom communities inhabiting them, therefore representing an important benchmark in view of the improvement of biological indices for the assessment of intermittent rivers.

The conservation value of human-modified landscapes for the world\u2019s primates

Land-use change pushes biodiversity into human-modified landscapes, where native ecosystems are surrounded by anthropic land covers (ALCs). Yet, the ability of species to use these emerging covers remains poorly understood. We quantified the use of ALCs by primates worldwide, and analyzed species’ attributes that predict such use. Most species use secondary forests and tree plantations, while only few use human settlements. ALCs are used for foraging by at least 86 species with an important conservation outcome: those that tolerate heavily modified ALCs are 26% more likely to have stable or increasing populations than the global average for all primates. There is no phylogenetic signal in ALCs use. Compared to all primates on Earth, species using ALCs are less often threatened with extinction, but more often diurnal, medium or large-bodied, not strictly arboreal, and habitat generalists. These findings provide valuable quantitative information for improving management practices for primate conservation worldwide.

Benthic primary production in emerged intertidal habitats provides resilience to high water column turbidity

Increasing inputs of terrigenous sediments from anthropic land use change elevates water column turbidity, reducing light availability to benthic primary producers that sustain estuarine food webs. For intertidal habitats, photosynthesis during low tide periods of emergence may provide resilience against this temporally displaced stressor, yet the significance of low tide production (PP) has largely been overlooked. Emerged and submerged benthic PP was measured in adjacent seagrass (Zostera muelleri) and microphytobenthos-dominated (sandflat) soft-sediment habitats at three locations encompassing a turbidity gradient. Light and dark benthic incubation chambers were used to measure the flux of CO2 across emerged sediments, and dissolved oxygen across submerged sediments to derive net (NPP) and gross (GPP) PP. Seagrass NPP and GPP exceeded sandflat habitats (by 3–8 times) at low turbidity sites during submergence and at all sites during emergence (p < 0.01), whereas habitat differences were absent (p > 0.1) in turbid locations. Emerged NPP and GPP were higher (2–16 times) than submerged in all habitats and locations (p < 0.01). When standardised by mean incident photosynthetically active radiation (PAR), the difference between emerged and submerged seagrass PP increased with site turbidity, from 2 to 26 times greater. In a global context of increasing inputs of terrigenous sediment to estuaries, emerged PP may be crucial for providing resilience against benthic productivity losses in highly turbid environments.

Spatio-temporal land-use changes in the Colima-Villa de Álvarez metropolitan area, and their relationship to floodings

El crecimiento demográfico, y por consiguiente los cambios de uso de suelo, se consideran entre los principales factores que pueden provocar el incremento de inundaciones en ciudades de países en desarrollo. Durante las últimas décadas en la Ciudad de Colima se ha incrementado la frecuencia con la que suceden inundaciones. Estos fenómenos ocurren mayormente durante tormentas tropicales asociadas a huracanes, como es el caso de Jova en 2011, Manuel en el 2013 y Patricia en el 2015, todas con lluvias acumuladas promedio de 200 mm en 24 h. También suceden con tormentas intensas y de corta duración a comienzos de la temporada de lluvia. Para definir los mecanismos que aumentan la ocurrencia de este fenómeno, se presenta un análisis espacio-temporal del cambio de uso de suelo, junto con la caracterización de suelos naturales y urbanos para el área metropolitana de Colima.Se definieron tres categorías principales de uso de suelo: Nativo (N1), Urbano (N4) y Agrícola (N5). Cada categoría tiene subcategorías dependiendo de la cobertura vegetal y/o nivel de urbanización. Imágenes SPOT adquiridas en 2005, 2009 y 2015 fueron clasificadas para analizar espacial y temporalmente los cambios de uso de suelo. Se analizaron treinta y dos muestras de suelo representativas de diferentes usos de suelo para obtener sus propiedades físicas y químicas, como granulometría, densidad aparente y de partícula, porosidad y contenido de materia orgánica. Pruebas de conductividad hidráulica in situ se hicieron usando un infiltrómetro por goteo.Con base en el análisis temporal y espacial de las imágenes SPOT, se pudo detectar que la mayoría de los cambios de uso de suelo corresponden al área urbana y agrícola; la primera mostrando un incremento y la segunda una drástica disminución, especialmente hacia el norte donde el crecimiento urbano es evidente durante el periodo 2005-2009. Los suelos en las áreas agrícolas resultaron ser los más permeables, mientras que los suelos constituido por material compactado para construcción corresponden a los menos permeables en el área; por lo tanto, el reemplazo de las zonas agrícolas por zonas habitacionales tiene un impacto significativo en el proceso de lluvia-escurrimiento. Estos resultados indican que mientras más zonas permeables sean substituidas por suelos perturbados, la capacidad de infiltración será reducida, incrementando la frecuencia de inundaciones en el área metropolitana Colima-Villa de Álvarez.Para prevenir y reducir el impacto destructivo de las inundaciones en el área metropolitana de Colima, se recomienda tener un manejo adecuado del cambio de uso de suelo y conservar las superficies permeables alrededor de la ciudad. Adicionalmente, es necesario revisarla infraestructura hidráulica existente de las zonas urbanas y definir los sitios adecuados para las futuras. Evitar desarrollos urbanos en zonas susceptibles a inundación a través de la buena planificación y la reglamentación, podría reducir las pérdidas de vidas y daños materiales producto de estos eventos.

Soil carbon, nitrogen and phosphorus changes under sugarcane expansion in Brazil

Historical data of land use change (LUC) indicated that the sugarcane expansion has mainly displaced pasture areas in Central–Southern Brazil, globally the largest producer, and that those pastures were prior established over native forests in the Cerrado biome. We sampled 3 chronosequences of land use comprising native vegetation (NV), pasture (PA), and sugarcane crop (SC) in the sugarcane expansion region to assess the effects of LUC on soil carbon, nitrogen, and labile phosphorus pools. Thirty years after conversion of NV to PA, we found significant losses of original soil organic matter (SOM) from NV, while insufficient new organic matter was introduced from tropical grasses into soil to offset the losses, reflecting in a net C emission of 0.4Mgha−1yr−1. These findings added to decreases in 15N signal indicated that labile portions of SOM are preserved under PA. Afterwards, in the firsts five years after LUC from PA to SC, sparse variations were found in SOM levels. After more than 20years of sugarcane crop, however, there were losses of 40 and 35% of C and N stocks, respectively, resulting in a rate of C emission of 1.3Mgha−1yr−1 totally caused by the respiration of SOM from C4-cycle plants. In addition, conversion of pastures to sugarcane mostly increased 15N signal, indicating an accumulation of more recalcitrant SOM under sugarcane. The microbe- and plant-available P showed site-specific responses to LUC as a function of different P-input managements, with the biological pool mostly accounting for more than 50% of the labile P in both anthropic land uses. With the projections of 6.4Mha of land required by 2021 for sugarcane expansion in Brazil to achieve ethanol's demand, this explanatory approach to the responses of SOM to LUC will contribute for an accurate assessment of the CO2 balance of sugarcane ethanol.

Anthropic land use and vegetation dynamics in mountain areas of Cavargna Valley (Lepontine Alps, Lombardy, N-Italy) during the Holocene

Anthropic land use and vegetation dynamics in mountain areas of Cavargna Valley (Lepontine Alps, Lombardy, N-Italy) during the Holocene

Extinction trends of threatened invertebrates in peninsular Spain

Using information from two recently published atlases of threatened invertebrate species in peninsular Spain, we examined the climatic, land use and geographic characteristics of the 100 km2 UTM cells with most likelihood of suffering extinctions (extinction cells), as well as the attributes of the species prone to population extinctions. Extinction cells have had significantly (1) lower precipitation values, (2) higher temperatures, (3) higher percentages of anthropic land uses or (4) higher rates of anthropization during the last 20 years than the remaining cells. Nevertheless, probable extinctions may occur under a wide range of climatic and anthropization change rates and these variables can only explain a low proportion (~5 %) of variability in the occurrence or number of extinction cells. Aquatic species seem to suffer higher local extinction rates than terrestrial species. Interestingly, many invertebrate species with approximately 25 or less occurrence cells are on a clear trajectory towards extinction. These results outline the difficulties and uncertainties in relating probable population extinctions with climatic and land use changes in the case of invertebrate data. However, they also suggest that a third of the considered Spanish threatened species could have lost some of their populations, and that current conservation efforts are insufficient to reverse this tendency.