Semi-arid Landscapes Research Articles

Spatial dynamics of soundscapes and biodiversity in a semi-arid landscape

Spatial dynamics of soundscapes and biodiversity in a semi-arid landscape

Land-Use and Land-Cover Classification in Semi-Arid Areas from Medium-Resolution Remote-Sensing Imagery: A Deep Learning Approach.

Detailed Land-Use and Land-Cover (LULC) information is of pivotal importance in, e.g., urban/rural planning, disaster management, and climate change adaptation. Recently, Deep Learning (DL) has emerged as a paradigm shift for LULC classification. To date, little research has focused on using DL methods for LULC mapping in semi-arid regions, and none that we are aware of have compared the use of different Sentinel-2 image band combinations for mapping LULC in semi-arid landscapes with deep Convolutional Neural Network (CNN) models. Sentinel-2 multispectral image bands have varying spatial resolutions, and there is often high spectral similarity of different LULC features in semi-arid regions; therefore, selection of suitable Sentinel-2 bands could be an important factor for LULC mapping in these areas. Our study contributes to the remote sensing literature by testing different Sentinel-2 bands, as well as the transferability of well-optimized CNNs, for semi-arid LULC classification in semi-arid regions. We first trained a CNN model in one semi-arid study site (Gujranwala city, Gujranwala Saddar and Wazirabadtownships, Pakistan), and then applied the pre-trained model to map LULC in two additional semi-arid study sites (Lahore and Faisalabad city, Pakistan). Two different composite images were compared: (i) a four-band composite with 10 m spatial resolution image bands (Near-Infrared (NIR), green, blue, and red bands), and (ii) a ten-band composite made by adding two Short Wave Infrared (SWIR) bands and four vegetation red-edge bands to the four-band composite. Experimental results corroborate the validity of the proposed CNN architecture. Notably, the four-band CNN model has shown robustness in semi-arid regions, where spatially and spectrally confusing land-covers are present.

The role of habitat features in patterns of population connectivity of two Mediterranean amphibians in arid landscapes of central Iberia

ContextMediterranean wetland ecosystems are in continuous decline due to human pressure. Amphibians are key elements of biotic communities of Mediterranean temporary ponds and streams, and their persistence depends on the availability and inter-connectivity of breeding sites.ObjectivesWe investigated the role of different factors potentially driving functional connectivity patterns in two amphibian species at the landscape and local scales. We focused on two Mediterranean endemic pond-breeding amphibians inhabiting semi-arid landscapes of central Spain, the common parsley frog (Pelodytes punctatus) and the common midwife toad (Alytes obstetricans).MethodsWe genotyped 336 individuals of P. punctatus and 318 of A. obstetricans from 17 and 16 breeding populations at 10 and 17 microsatellite loci, respectively. We used remotely sensed vegetation/moisture indices and land use/cover data to derive optimized resistance surfaces and test their association with estimates of gene flow and migration rates across populations.ResultsWe found evidence for higher population connectivity in common midwife toads than in common parsley frogs, with a strong effect of water availability in patterns of population connectivity of both species. However, the two species differ in the role of landscape features on population connectivity, with the distance and spatial distribution of artificial land-use types positively influencing connectivity in A. obstetricans and meadows/pastureland favouring P. punctatus. This is in line with reported breeding site preferences for the two species, with A. obstetricans successfully breeding in artificial water bodies that P. punctatus generally avoid.ConclusionsThis study highlights the importance of assessing species–habitat relationships shaping connectivity when developing and implementing conservation and management actions to benefit fragmented amphibian populations in the Mediterranean region. Our results show that amphibian species respond differently, even contrastingly to landscape features and thus require alternative, complementary strategies to improve population connectivity and ensure long-term viability.

Bee richness and abundance in small fruit farms from semiarid landscape, NE, Brazil

Bee diversity and current status of native populations is barely known in cropland from semiarid Sergipe, where fruit production is a growing activity among small farmers. Psidium guajava L. (Myrtaceae) is spread among small growers in Canindé de São Francisco and Poço Redondo in Sergipe state, Northeastern Brazil, in semiarid Caatinga, causing landscape change and habitat loss. Available evidences support that cross-pollination provided by bees may increase seed set and fruit production, despite self-pollination. We aimed to access bee richness and abundance within Guava orchard and identify landscape parameters important to these patterns. Survey was conducted in ten Guava orchards during the flowering period (n=10) from May to December 2017. Nine bee species were recorded and the high density and generalist bees Trigona spinipes and Apis mellifera comprised 92% of the flower visitors. No other social native bees were found, and solitary bees were scarce. No significant influence of landscape structure was found for bee richness, while bee abundance was affected by environmental diversity, isolation, and distance to caatinga patches and continuous vegetation reserves. Landscape simplification threatened bee diversity and pollination services. These results highlight the importance of providing bee habitat within farmlands, rearing stingless bees and restoring natural habitats along streams to increase wild bee populations within crops.

Troubled waters: Water availability drives human-baboon encounters in a protected, semi-arid landscape

Most animal habitats are affected by humans. While some species tolerate and even benefit from these changes, others suffer. Understanding when and how human-altered landscapes affect animal behavior, health, reproduction, and survival is essential to species management in a human-dominated world. Here we use 27 years of data on human-baboon encounters in a protected, semi-arid ecosystem in Kenya to: (i) identify spatial, environmental, and group-level predictors of baboon encounters with pastoralists; (ii) test whether human-built water sources alter baboon ranging patterns; and (iii) test if human encounters are linked to baboon survival, reproduction, and health. We find that the primary driver of human-baboon encounters is water availability. During dry periods, pastoralists migrate into baboon rangelands, leading to frequent human-baboon encounters, especially near water wells. Further, the baboons shift their ranges to encompass newly built wells and move away from abandoned, dried-up wells. Since 2006, a third of adult baboon deaths were linked to violent encounters with humans or their dogs. Human encounters were also linked to high infant mortality and parasite diversity in females (but this effect could not be disentangled from seasonal confounds). For wild baboons, life in protected, pastoralist conservancies presents a double-edged sword: human-built wells enable the baboons to access water during dry periods, but these wells lead to encounters with humans, which have become a common source of baboon mortality. Together, our results serve as a comprehensive case study of anthropogenic effects on wild primates, highlighting the complex interactions between humans and wildlife in protected areas.

Short-term recovery of soil and pine tree canopy after late prescribed burning in a semi-arid landscape

Climate change worsening due to global warming and progressive abandonment in rural areas mean that wildfires are increasing in extent and severity terms, and are one of the major disturbances in the Mediterranean Basin. To mitigate these disturbances, preventive management tools need to be used. Fire employment is being implemented, known as prescribed burnings, as forestry actions to change vegetation lines both vertically and horizontally to eliminate forest fuel load continuity. This study aimed to know the ecological effects of late prescribed burning treatments under mixed trees. Prescribed burns were carried out in October 2019 in the municipality of Ayna, Albacete (SE Spain). To assess the short-term (12-month) fire impact on soil, we measured soil respiration with a CO2 flow chamber and analyzed soil physico-chemical properties. We also used minidisc infiltrometers to analyze soil repellency and soil hydraulic conductivity over a 1-year monitoring period. In addition, we evaluated the effects on tree strata by performing chemical nature analyses of fallen needles in Pinus pinaster after prescribed burning. According to our initial hypotheses, the results did not show significant changes in any parameter evaluated during the study period. However, some variables were affected in the first 3 months, needlefall and in microbiological activity, such as variations in soil physico-chemical properties, which can be due to long dry seasons combined with prescribed burning. This study attempts to observe and make known the effects that low-intensity prescribed burning has on soil and needlefall, which are relevant for updating forest management tools.

Relationships among water, food, energy, and ecosystems in the Mid-Latitude Region in the context of sustainable development goals

The progress of the global effort to achieve Sustainable Development Goals (SDGs) is increasingly impeded by the degradation of critical and fundamental resources such as water, food, energy, and ecosystem services. The Mid-Latitude Region (MLR) of the world is at the forefront of confronting these challenges due to rapid population growth, increasing poverty, and drought and climate change that are exacerbating the transition of semi-arid landscapes to deserts. While scientific studies are accumulating around the water–food–energy–ecosystem nexus, efforts to simulate how the linkages among the elements relate to SDGs are lacking in the MLR. We attempt to review and analyze existing literature about how water–food–energy–ecosystems operate, interact, and relate to SDGs. We identified 37 relationships and ascertained the nature of their interactions, of which 12 are significant and have direct bearings on the SDGs. The findings show that most studies and approaches that address the nexus challenges in the MLR exist in silos. In addition, there is a lack of a scientific approach to quantify how the nexus operates and relates to SDGs. For instance, past studies show that deforestation for agriculture could increase food security. However, there is a weak focus on trade-offs (e.g., loss of ecosystem services due to deforestation). Deforestation is also shown to have a negative relationship with the quantity and quality of water (SDG6) as well as the functionality of an ecosystem (SDG15). Furthermore, the review has indicated a negative relationship between irrigated agriculture and water and a positive relationship with food. This directly implies that water and food issues must be addressed in tandem and not separately if we are to achieve SDGs 2 and 6. The review supports the idea that water, food, energy, and ecosystem services cannot be managed separately, and that future approaches must focus on integrating and optimizing the connections among them to ensure sustainable development.

Spatial Analysis of the Geoecological Adequability Index in Semi-Arid Watersheds, Northeast of Brazil

stract This research aimed to perform a comparative analysis of Geoecological Adequability (GA) in two semi-arid watersheds in Northeastern Brazil based on a classification carried out in a GIS (Geographic Information System) environment using the algebra map tool. The GA calculation reveals the interactions between landscape components through GIS, namely soil, slope, vegetation and land cover. Weights were assigned (1, 2 or 3) to the different cartographic layers of the geoecological components measured using the algebra map tool, through the arithmetic means, to classify the semiarid basins into different adequability levels, as follows: adequate, partially adequate and inadequate to anthropic uses. These procedures verified the predominance of the “adequate” class with a territorial area above 42% in both investigated basins; the “partially adequate” level and the second most comprehensive class comprised values between 30% and 40%; and, while smaller territorial extensions, below 20%, were “inadequate”. Based on these findings, it was possible to measure the most suitable areas for anthropic use in the studied basins and indicate the areas that should be conserved, with emphasis on protection and/or regeneration of the natural vegetation cover. This is important information concerning the planning and environmental management of these semi-arid landscapes in an objective and efficient way

Can we look bee colonies as biological indicators of forest ecosystem? A comparative study of the occurrence of bee colonies in some protected areas of Rajasthan, India

Survey of colonies of Apis dorsata was conducted in five reserves, including Keoladeo national park (KNP), Jhalana leopard reserve (JLR), Sariska tiger reserve (STR), Sitamata wildlife sanctuary (SWS), Bassi wildlife sanctuary (BWS), located in semi-arid landscape of Rajasthan. Bee colonies were observed mostly on medium to large sized trees in the study areas demonstrating the role of size of trees irrespective of species type. The observation of high density of bee colonies in KNP (d = 7.1 colonies/km²) can be attributed to low intensity of anthropogenic pressures that is evident from low PIPUA (p' = 1.68). In contrast observation of low density of bee colonies in STR and SWS (d = 0.2, 0.1 colonies/km²) can be attributed to high anthropogenic interferences which is evident from the observation of high PIPUA (p' = 8.04, 8.08 respectively). Thus, the bee colonies can be considered as biological indicator of forest ecosystem.

Surface runoff and sediment yield response under the rainfall simulation condition controlled by soil variables of a semi-arid landscape

Surface runoff and sediment yield response under the rainfall simulation condition controlled by soil variables of a semi-arid landscape

Wetland health, water quality, and resident perceptions of declining ecosystem services: a case study of Mount Abu, Rajasthan, India.

Ecosystem services provided by wetlands are essential for communities living near wetlands, especially in an underdeveloped semi-arid landscape. The land use land cover changes and ecosystem degradation and water quality change over the past few decades have had immense effects on declining wetland ecosystem services. With the degradation, it is exerting superfluous effects on wetland communities including loss of livelihood, and decline in other wetland services like fishing, aquaculture, fuelwood, fodder, and many more. The present study attempts to assess the changing nature of wetland health, water quality, and declining ecosystem services of Mount Abu wetlands in Rajasthan, India. For assessing the change of wetland extent, we have used the remote sensing-based data for preparation of land use land cover change from 1992 to 2020. The water samples have been collected from the wetland, and different biophysical parameters of the water have been tested in the laboratory. A questionnaire-based household survey has been conducted to understand the perception of the wetland communities on the loss of ecosystem services over three decades. Further, a correlation and cluster assessment has been conducted to understand the degradation of wetland health in the selected wetlands. The study results indicated deteriorating conditions of wetland health and declining ecosystem services in the study area over the time periods. The land use land cover change analysis indicated a decrease in the spatial extent of the wetlands in the study area. Wetland communities are being affected due to the degradation of wetland health. The study recommended executing a wetland management plan for long-term conservation and livelihood management for the Mount Abu wetlands and communities.

A checklist of avifauna from different habitats of semi-arid landscape in western parts (Mandsaur and Ratlam districts) of Madhya Pradesh, India

We prepared a checklist of avian species recorded from two western districts (Mandsaur and Ratlam) of Madhya Pradesh, situated in a semi-arid region with comments on their habitat preference, feeding habits, migratory, and conservation status; 133 bird species belonging to 47 families were recorded during the present study. About 30% of the species were migratory in status. In terms of habitat fidelity, 74 avian species were found only in a single habitat. Habitat-wise avian richness varied widely. Among five habitats identified during the present study, wetland supported the highest number (69) of avian species of which 58 species were exclusively recorded from this habitat. Eight foraging guilds were identified among which omnivores were dominant. Six species of globally threatened and seven species of near-threatened species were recorded during the present study. The presence of significant numbers of winter migrants and globally threatened species indicated the importance, both ecologically and biologically, of the semi-arid landscape for breeding and migratory birds. Therefore, this work will provide baseline information to conservationists for the development of conservation and management policies for the two districts.

Diet of the Indian fox (Vulpes bengalensis) in dry scrubland of north Gujarat, India

Indian fox Vulpes bengalensis, a mesocarnivore of the Indian subcontinent, is distributed widely in all kinds of habitats in India except the Western Ghats. The Indian fox prefers semi-arid landscapes with low rainfall where it is easy to hunt and dig dens and where the vegetation is mainly short grasslands or scrub, thorn thickets or dry deciduous forests. They mostly avoid dense forests, steep terrain, tall grasslands, and true deserts. The Indian fox is listed as of Least Concern (LC) by the IUCN and legally protected in India under schedule II of the Indian Wildlife Protection Act 1972. An opportunistic and omnivorous feeder, its diet includes insects, scorpions, centipedes, small rodents, monitor lizards and other reptiles, ground nesting birds, their eggs and fruit such as Ziziphus sp. (Rhamnaceae), Citrullus vulgaris (Cucurbitaceae), Azadirachta indica (Meliaceae), Mangifera indica (Anacardiaceae), Syzigium cumini (Myrtaceae), Melia azedarach (Meliaceae), and Ficus bengalensis (Moraceae). Some local shepherds have also reported seeing Indian foxes feed on the freshly voided pellets of sheep. Their presence and density in any area is closely related to the abundance of food.

Using Remote Sensing to Estimate Understorey Biomass in Semi-Arid Woodlands of South-Eastern Australia

Monitoring ground layer biomass, and therefore forage availability, is important for managing large, vertebrate herbivore populations for conservation. Remote sensing allows for frequent observations over broad spatial scales, capturing changes in biomass over the landscape and through time. In this study, we explored different satellite-derived vegetation indices (VIs) for their utility in estimating understorey biomass in semi-arid woodlands of south-eastern Australia. Relationships between VIs and understorey biomass data have not been established in these particular semi-arid communities. Managers want to use forage availability to inform cull targets for western grey kangaroos (Macropus fuliginosus), to minimise the risk that browsing poses to regeneration in threatened woodland communities when grass biomass is low. We attempted to develop relationships between VIs and understorey biomass data collected over seven seasons across open and wooded vegetation types. Generalised Linear Mixed Models (GLMMs) were used to describe relationships between understorey biomass and VIs. Total understorey biomass (live and dead, all growth forms) was best described using the Tasselled Cap (TC) greenness index. The combined TC brightness and Modified Soil Adjusted Vegetation Index (MSAVI) ranked best for live understorey biomass (all growth forms), and grass (live and dead) biomass was best described by a combination of TC brightness and greenness indices. Models performed best for grass biomass, explaining 70% of variation in external validation when predicting to the same sites in a new season. However, we found empirical relationships were not transferrable to data collected from new sites. Including other variables (soil moisture, tree cover, and dominant understorey growth form) improved model performance when predicting to new sites. Anticipating a drop in forage availability is critical for the management of grazing pressure for woodland regeneration, however, predicting understorey biomass through space and time is a challenge. Whilst remotely sensed VIs are promising as an easily-available source of vegetation information, additional landscape-scale data are required before they can be considered a cost-efficient method of understorey biomass estimation in this semi-arid landscape.

Assessment of livestock grazing pressure in key tiger habitat in a semi-arid landscape in Western India

Assessment of livestock grazing pressure in key tiger habitat in a semi-arid landscape in Western India

Simulating salinity transport in High-Desert landscapes using APEX-MODFLOW-Salt

Salt pollution in semi-arid landscapes is detrimental to food production, ecosystem biodiversity, soil health, and water supply. High-desert watersheds, due to natural salt deposits, are a key source of salinity in river basins. Although studies have aimed at simulating and estimating salt movement in these landscapes, approaches have relied on lumped, statistical procedures that treat salt as a conservative solute rather than a collection of reactive salt ions. These approaches are limited in quantifying the source, transport, and fate of salt under both historical and future conditions. This study presents a new physically-based spatially distributed salinity transport model for watershed systems of various spatial scales. The model combines the watershed model APEX, the groundwater model MODFLOW, the groundwater reactive transport model RT3D, and a new salinity module to simulate the fate and reactive transport of eight major ions (SO42-, Cl-, CO32–, HCO3–, Ca2+, Na+, Mg2+, K+) in soils, aquifers, and streams of a complex watershed system. Salt loading to streams occurs via surface runoff, erosion runoff, soil lateral flow, and groundwater discharge. The linked APEX-MODFLOW-Salt model is applied to the Price River Watershed (PRW) (4,886 km2), Utah, USA, a portion of the salinity-laden Upper Colorado River Basin, to estimate spatio-temporal loadings from the various hydrologic pathways and total salt yield in the river during 1995–2015. Results indicate that the vast majority (89%) of dissolved salt in the Price River and its tributaries is loaded by groundwater, and that more than half of the salt is in the form of sulfate (SO4). Erosion runoff due to rainfall events is responsible for only 1.5% of total salt yield in the PRW. Total annual dissolved salt loading from the PRW through its outlet is approximately 63,500 Mg. From the results, we conclude that managing salinity in the PRW may need to focus principally on groundwater and its sources.

An overview of stranded cetacean scavenging in Atlantic southern Africa since the Earlier Stone Age

Along the southern African coastal plain, human occupation is documented since the end of the Early Pleistocene. The archaeological, palaeoenvironemental and ethnographic records suggest that in these arid to semi-arid landscapes where inland resources are sometimes scarce, coastal zones were attractive to past human populations. Among the intertidal resources, stranded marine mammals are known to have been sporadically available from several million years ago and have been scavenged by human groups since at least the Middle Pleistocene. This appears to be a regional behaviour rooted deep in time. In this paper, we review the ethnographic and archaeological data related to stranded marine mammal scavenging from the Earlier Stone Age up to recent times and we discuss the specificities of this subsistence behavior in Atlantic southern Africa.

A new species of Protozantaena Perkins, 1997 from the Great Escarpment of South Africa (Coleoptera, Hydraenidae).

Protozantaena birdi sp. nov. is described, based on specimens collected from the Compassberg and Winterberg ranges in the Eastern Cape Great Escarpment, South Africa; the seventh known species of the genus. Morphologically, the new species appears closely related to P. labrata Perkins, 1997, described from the Naukluft Range in the Central Namibian Great Escarpment. Both species live in the margins of small streams in open, semi-arid landscapes.

A revision of the Palaearctic Pimeliini (Coleoptera: Tenebrionidae): a comparative analysis and systematic position of Eastern European and Asian taxa with dorso-lateral eyes

A taxonomic review of tenebrionid platyopoid genera of the subfamily Pimeliinae from Eastern Europe, Central Asia, Afghanistan, Iran and Pakistan is given. This group of taxa was known before 1994 as the tribe Platyopini Motschulsky, 1849, which is now interpreted as a junior synonym of Pimeliini Latreille, 1802. The group is different from other Pimeliini in having dorso-lateral eyes, located above the level of the genae, and it includes the following ultrapsammophilic genera at least from Central and Southern Asia: Apatopsis Semenov, 1891, Habrochiton Semenov-Tjan-Shansky, 1907, Habrobates Semenov, 1903 [= Kawiria Schuster, 1935 syn. nov.], Dietomorpha Reymond, 1938, Przewalskia Semenov, 1893, Mantichorula Reitter, 1889, Platyope Fischer von Waldheim, 1820 [= Homopsis Semenov, 1893 syn. nov.], Earophanta Semenov, 1903. These genera are distributed in almost all large deserts of Palaearctic Asia: Karakum, Kyzylkum, Muyunkum, Taklamakan, Gobi, Registan, Dasht-e-Kawir, Dasht-e-Lut, as well as in other arid and semi-arid sandy landscapes from European Russia to the south of Eastern Siberia. The group of platyopoid genera is polyphyletic. We propose at least two monophyletic branches: the Habrobates genus group (the first four genera mentioned above), which represents the subtribe Habrobatina Nabozhenko & S. Chigray subtrib. nov. and the Platyope genus group (latter four genera) within the nominotypical subtribe. A new species is described from Pakistan (Balochistan): Dietomorpha gonzalesi S. Chigray & Nabozhenko sp. nov. Platyope granulata Fischer von Waldheim, 1820 is recorded for Kazakhstan for the first time. The following synonymy is resurrected: Apatopsis grombczewskii Semenov, 1890 = Apatopsis conradti Semenov, 1890, syn. resurr. Two new combinations resulting from the synonymy of genera are given: Habrobates gabrieli Schuster, 1935 comb. nov. (from Kawiria), Platyope grumi Semenov, 1893 comb. nov. (from Homopsis). Lectotypes are designated for the following taxa: Apatopsis grombczewskii (Semenov, 1891), Apatopsis conradti Semenov, 1891, Habrochiton vernus Semenov-Tjan-Shansky, 1907, Habrobates vernalis Semenov, 1903, Kawiria gabrieli Schuster, 1935, Platyope dilatata Reitter, 1887; Mantichorula semenowi Reitter, 1889, Mantichorula grandis Semenov, 1893, Homopsis grumi Semenov, 1893, Platyope serrata Semenov, 1893, Platyope planidorsis Reitter, 1889, Platyope tomentosa Semenov, 1893. Additional information for type specimens studied by the authors is given for Habrochiton primaeveris Semenov-Tjan-Shansky, 1907 (holotype), Habrobates vejisovi Kelejnikova, 1977, Platyope ordossica Semenov-Tjan-Shansky, 1907 (holotype), Earophanta autumnalis Semenov, 1903 (holotype, junior synonym of E. planidorsis Reitter, 1889), Earophanta loudoni Semenov, 1903 (holotype, junior synonym of Earophanta pilosissima Reitter, 1895), Earophanta pubescens Skopin, 1960 (holotype, paratypes), Earophanta beludzhistana Bogatchev, 1957 (holotype).

The effect of formation processes on the frequency of palaeolithic cave sites in semiarid zones: Insights from Kazakhstan

AbstractCentral Asian caves with Palaeolithic deposits are few, but they provide a rich record of human fossils and cultural assemblages that has been used to model Late Pleistocene hominin dispersals. However, previous research has not yet systematically evaluated the formation processes that influence the frequency of Palaeolithic cave sites in the region. To address this deficiency, we combined field survey and micromorphological analyses in the piedmont zone of south Kazakhstan. Here, we present our preliminary results focusing on selected sites of the Qaratau mountains. Sediment cover varies among the surveyed caves, and loess‐like sediments dominate the cave sequences. The preservation of cave deposits is influenced by reworking of cave sediments within the caves but also by the broader erosional processes that shape semiarid landscapes. Ultimately, deposits of potentially Pleistocene age are scarce. Our study provides new data in the geoarchaeologically neglected region of Central Asia and demonstrates that micromorphology has great analytical potential even within the limitations of rigorous survey projects. We outline some of the processes that influence the formation and preservation of cave deposits in Kazakhstan, as well as broader implications for the distribution of Palaeolithic cave sites in Central Asia and other semiarid environments.