Semi-arid Ecosystems Research Articles

The Functional Response of Estuarine Fish Communities to Hydrologic Change in a Semi-Arid Ecosystem

Functional assessment approaches were used to identify the responses of fish to environmental change in the San Antonio Bay System (Texas, USA). Using a 26-year coastal fisheries dataset (1993–2018), multivariate analyses revealed relationships between functional group abundance and freshwater inflows in the upper segments (Hynes Bay and Guadalupe Bay), but the patterns were decoupled from inflows in the lower bay segments (San Antonio Bay, Ayres Bay and Espiritu Santo Bay). In Hynes and Guadalupe Bays, freshwater migrant carnivores accounted for a significant fraction of the community irrespective of the gear, year or flow. Freshwater stragglers (omnivores and carnivores) were often present in the upper reaches of the bay. In the lower reaches, marine migrant omnivores were present during high and low flows in Espiritu Santos Bay, but only during low flows in Ayres Bay. Marine migrant carnivores were more important in gill nets irrespective of the flow conditions. The five most abundant fish were estuarine resident carnivores and omnivores, accounting for 53.5% of the community. Declines in the abundance of functional groups occurred during the 2011–2014 drought, with rebounds in 2015–2018. Functional methodologies provide insights into estuarine ecosystems and can serve as management tools to assess changes in fish assemblages.

Understanding soil and ecosystem respiration in a dune-meadow cascade ecosystem

Arid and semi-arid regions, which account for more than 30% of the Earth's land area, increasingly dominate the spatiotemporal trends in global carbon fluxes. The Horqin Sandy Land is a typical semi-arid fragile ecosystem in northern China. Understanding the components of the carbon budget in ecosystems under conditions of extreme soil moisture limitations provides a foundation for comprehending the carbon balance in semi-arid ecosystems. The seasonal and diurnal variations in soil respiration (Rs) in semi-mobile dune (SD) and meadow wetland (MW) ecosystems of the Horqin Sandy Land were examined, and the sources of CO2 emissions from Rs were identified using stable carbon isotopes. The responses of Rs and ecosystem respiration (Reco) to environmental temperature, moisture and leaf area index (LAI) were revealed. The results showed that on a seasonal scale, in SD with soil moisture content (Ms) below field capacity (FC), Ms had a greater influence on Rs than soil temperature (Ts) during the growing season. Changes in the LAI during the middle and late growth period affected Rs by altering root carbon supply. In MW, the most favorable Ms for Rs was near FC. The increase in LAI before mowing could effectively promote root and soil microbial respiration, and the decomposition of litter driven by Ts was the main form of Rs at this time. After mowing, root respiration and soil microbial respiration were the main processes contributing to CO2 emissions. On a daily scale, relative humidity (RH) dominated the Rs variation under dry conditions, whereas in other conditions, the Rs was adequately explained by temperature in SD and MW. The overall Reco was larger than Rs, but occasionally Rs was greater than Reco. The effects of temperature, moisture and LAI on Reco and Rs varied with growing season. Adding factors, such as ecosystem type, vegetation growth, water, and heat, to the carbon cycle model can improve predictions of carbon emissions, and aid in further management decisions in arid and semi-arid areas.

Understanding the Sorghum-growing Soils in a Semi-arid Ecosystem of Telangana, India and Assessing their Land Suitability for Sorghum Cultivation

Background: Sorghum (Jowar), a nutritionally rich, great millet is frequently cultivated in semi-arid tracts of India but at places without considering the suitable soil-sites, which result in lower productivity. Thus, understanding of sorghum-growing pedo-environment vis-à-vis crop requirements is a pre-requisite for soil-site evaluation of crop and hence present case study was carried out in Mahabubnagar rural mandal of Mahabubnagar district, Telangana state. Methods: The detailed soil survey (1:10000 scale) of Mahabubnagar Rural mandal (Mahabubnagar district), Telangana was carried out using Sentinel 2 satellite data and mapped with 66 mapping units. These mapping units along with relevant physical and chemical properties were evaluated for their suitability for sorghum farming. Result: Our results indicated that major sorghum-growing soils of Mahabubnagar Rural mandal have been grouped as Typic Rhodustalfs, Aquic Haplustalfs, and Typic Haplusterts at the sub group level. Out of the 18-soil series, major sorghum-growing soils belong to Telugugudam, Kotakadira and Potanpalle series occupying 7.56 % of the geographical area. The soil-site evaluation study indicated that the maximum area (33.99 per cent) was rated as marginally suitable with limitations of gravelliness, nutrient availability, rooting conditions, and texture while 1.51 per cent area was highly suitable for sorghum cultivation.

Long-term alfalfa planting mediates the coupling of soil water and organic carbon storage in a semi-arid area of the Loess Plateau, China.

The key to restoring arid and semi-arid ecosystems is maintaining soil water and organic carbon contents. Alfalfa (Medicago sativa L.) is a high-yield perennial forage crop and performs ecological functions as a drought-resistance leguminous herb. It has been widely planted for reconstruction of degraded soils in the Loess Plateau in northwestern China, but long-term planting may affect soil carbon-water coupling and lead to crop yield reduction. To maximize the benefits of reconstructed grassland, this study explored the couplings of soil water, organic carbon, and alfalfa productivity along a reconstruction chronosequence in a semi-arid area of the Loess Plateau. Space-for-time substitution approach was used to select different-aged stands of reconstructed grassland (1, 5, 7, 10, 15, 20, 30 years old). Alfalfa above-ground biomass (AGB), soil water storage (SWS), organic carbon storage (SOCS), and carbon-water coupling coordination degree (D) were measured in the 0-100 cm soil profile. Alfalfa AGB reached a peak in the 7th year, and the degradation began in the 10th year. Both SWS and SOCS varied nonlinearly with stand age. The greatest loss of SWS occurred in the 15th year (80-100 cm depth), whereas the largest increase of SOCS occurred in the 30th year (0-20 cm depth). There was a negative feedback relationship between AGB and SWS over the 30-year study period (Pearson r = -0.835, P = 0.098). AGB and SOCS initially showed a trade-off within the first 10 years (Pearson r = -0.7431, P = 0.2569), in contrast to their positive feedback in the 20-30th years (Pearson r = 0.9978, P = 0.0421). A decoupling between SWS and SOCS (D < 0.6) was observed after 12 years of alfalfa planting. For agricultural production, a greater supply of water and organic fertilizer is required from the 7th year of alfalfa planting, and reseeding may be needed around the 10th year to prolong the life of alfalfa community. Alfalfa should be planted for no more than 12 consecutive years in the study area for ecological protection.

Development of a Mexican corn landrace, Northern Conical, under temperature and rainfall conditions predicted by the middle of this century: an experimental field approach

Background: Corn is the most important crop in Mexico, but it can be affected by climate change. Small farmers from arid and semiarid ecosystems mainly use rainfed native landraces with short productive cycles (less than 90 days), which are adapted to elevated temperatures and intense drought. Among these landraces we can find the Norther Conical corn. Hypothesis: As Northern Conical seems to be adapted to arid agroecosystems, we hypothesize that this corn landrace can tolerate the mid-century climate change conditions. Studied species: Zea mays subsp. mays (Poaceae), Northern Conical landrace. Study site and dates: An abandoned agricultural field in San Luis Potosí, central Mexico, between August and October 2022. Methods: In a field experiment, corn seeds were sowed under the conditions of higher temperature and lower rainfall predicted by the middle of this century (period 2041-2060), as well as under the current climate. Emergence and survival of plants were regularly monitored, and their functional responses were measured by the end of the experiment. Results: Northern Conical plants performed better (in terms of emergence, survival, growth rates, and photosynthetic performance) under higher temperature and lower rainfall, as compared with those developed under the current climate. Conclusions: Our results suggest that the Northern Conical corn landrace may tolerate the increases in aridity expected in the short term. However, simulations under contrasting environmental and ontogenetical conditions are needed.

Stronger biogeographical pattern of bacterioplankton communities than biofilm communities along a riverine ecosystem: a local scale study of the Kaidu river in the arid and semi-arid northwest of China

Although the biogeographical pattern and mechanisms underlying microbial assembly have been well-explored in lentic ecosystems, the relevant scenarios in lotic ecosystems remain poorly understood. By sequencing the bacterial communities in bacterioplankton and biofilm, our study detected their distance-decay relationship (DDR), and the balance between deterministic and stochastic processes, along the Kaidu river in an arid and semi-arid region of northwest China. Our results revealed that bacterioplankton and biofilm had significantly contrasting community structures. The bacterioplankton communities showed a gradually decreasing trend in alpha-diversity from the headwater to the river mouth, contrasting with the alpha-diversity of biofilm communities which was constant along the river length. Both bacterioplankton and biofilm showed significant DDRs along the 500-km river corridor with the slope of the bacterioplankton DDR being steeper than that of the biofilm DDR, which implies a stronger biogeography of bacterioplankton than biofilm. Relative to biofilm communities, the species interactions formed a denser and more complex network in the bacterioplankton communities than in the biofilm communities. Our results also revealed that there was a transition of community assembly from deterministic to stochastic processes upstream to downstream, although both the bacterioplankton and biofilm communities were mainly regulated by deterministic processes within the entire river. All these empirical results expand our knowledge of microbial ecology in an arid and semi-arid lotic ecosystem.

Analysis of Canopy Interception Characteristics and Influencing Factors in Typical Artificial Forest in the Loess Plateau Semi-Arid Region

Interception loss (IL) is an important process in the hydrological cycle within semi-arid forest ecosystems, directly affecting the amount of effective rainfall. However, the factors influencing IL during individual rainfall events remain to be quantified. This study collected rainfall, vegetation, and interception data during the 2022 and 2023 growing seasons in a typical black locust forest within the Zhifanggou watershed. It employed the Random Forest Regression (RFR) and back-propagation neural network (BPNN) methods to quantitatively evaluate the contribution rates of various factors to the IL and interception loss percentage (ILP). The IL among the 48 effective rainfall events was 172.05 mm, accounting for 19.54% of the rainfall amount. IL and ILP increased as the distance from the trunk decreased. During all rainfall events, both IL and ILP were significantly negatively correlated with the leaf area index (LAI) and canopy cover (CC); IL is significantly positively correlated with total rainfall (TR) and rainfall intensity (RI), while ILP is significantly negatively correlated with TR, RI, and rainfall duration (RD). The BPNN and RFR results indicated that rainfall, canopy, and tree characteristics contributed 43.06%, 44.79%, and 12.15% to IL, respectively, and 57.27%, 34.09%, and 8.63% to ILP, respectively. TR, CC, and LAI represented the primary influencing factors. Rainfall and canopy characteristics were the main factors affecting IL (ILP). As rainfall event magnitude increases, canopy contributions to IL and ILP decrease. In semi-arid areas, managing forest canopies to control IL helps address water imbalances in ecosystems.

Restoration of soil multifunctional indicators requires more than thirty years in degraded shrubland of a semi-arid mountainous ecosystem

Vegetation degradation in natural environments leads to considerable fluctuations in soil function indicators, particularly in the sensitive and delicate habitats of semi-arid regions. In this study, the dynamic of both litter and soil properties was examined in northern Iran, in sites with Crataegus melanocarpa and Berberis integerrima dominance. The chosen sites have been degraded in 1993 due to exploitation for fuel production. Litter and soil (0–10, 10–20 and 20–30 cm depths) samples were collected in sites that have been degraded [i.e., 10-years post-degradation (2003), 20-years post-degradation (2013), and 30-years post-degradation (2023)]. A site not to exposed to degradation (year 2023) was also included as a control. In total, 48 litter samples (4 study sites × 12 samples) and 144 soil samples (4 study sites × 3 depths × 12 samples) were collected. Our findings showed a significant reduction of approximately 60–70% in the chemical characteristics of the litter, such as phosphorus (P) and magnesium (Mg) after 10-years post-degradation (2003) compared to the control site. Soil fertility indicators were also reduced 2–6 times as a result of habitat degradation. Aligned with this, the biota population in the 10-year post-degradation site showed a decrease of 70–90% with respect to the control. Moreover, the densities of fungi and bacteria decreased by approximately 30%–70% and 45–80% respectively compared to the 30-year post-degraded site. The peak activation of soil enzymes including urease, acid phosphatase, arylsulfatase, and invertase was found in the site that was not subjected to degradation, being 3.5, 5.8, 6.7 and 6.7- times higher in comparison to the 10-year post-degradation site. Overall, the results showed that in the non-degraded ecosystems, the input of plant-based organic matter was accompanied by an increase in soil fertility, organism population and soil function. This pinpoints the importance of protecting plant species in these areas, while in degraded areas planting native species adapted to the region's climate and fertilization could significantly contribute to restoring these areas.

Climate Change Adaptation and Resource Resilience in Semi-Arid Regions: Strategies, Challenges, and Case Studies

Semi-arid regions face unique climate change challenges that threaten local ecosystems, agriculture, and water resources. This review explores climate adaptation strategies, resource resilience practices, and policy interventions tailored to semi-arid ecosystems, with a focus on Rajasthan, India, as a representative region. Key strategies include sustainable water resource management, soil conservation, and climate-smart agriculture. Through case studies and a comparative global analysis, this review underscores the importance of blending traditional and modern practices to enhance resilience and advocates for policy and technological innovation to support sustainable adaptation. Insights gained from this review may serve as a foundation for adaptation strategies applicable to other semi-arid regions globally.

Gastrointestinal parasite prevalence, diversity and association in free-ranging Chacma baboon troops in a semi-arid savanna ecosystem of Zimbabwe

Free-ranging Chacma baboon species are known to harbour a wide range of zoonotic parasites, and their frequent close interactions with humans pose a risk of transmission of zoonotic parasites between the two species. This research study focused on understanding parasite dynamics in free-ranging baboon populations that inhabit human-wildlife interface areas, a case of Gwanda State University's Epoch Mine campus in Filabusi at Insiza district. A descriptive and analytical cross-sectional design was used to investigate the prevalence, diversity and association of gastrointestinal parasites among three baboon troops found at the Epoch Mine campus. One hundred and twenty (120) fresh faecal samples were collected from the three troops between February and September 2023. The centrifugal floatation technique was used to process and analyse faecal samples, and parasite ova and cysts were identified using morphological features like shape and size. The prevalence of the parasite taxa and a chi-squared multiple comparison test was computed. Results showed significant differences among most parasite taxa except Coccidia spp and Entamoeba spp among the three troops. The Shannon–Wiener (H′) index was used to calculate diversity and graphs were utilized to present the association. The Kruskal-Wallis tests showed no significant difference in parasite diversity among the three troops. Although troop-parasite association showed different parasite species for each troop, helminths Strongylid spp. and Schistosoma spp. were highly common across all three troops. Troop 1 and 3 were associated with four parasite taxa, whereas Troop 2 had only three. The study reveals the presence of gastro-intestinal parasites of public health concern, as they are capable of causing diseases in humans and domestic animals. The study, therefore, underscores the importance of understanding parasite-host dynamics in mitigating zoonotic disease transmission and suggests the need to generate baseline data for mitigating zoonotic diseases and maintaining a healthy ecosystem.

Tracking tree demography and forest dynamics at scale using remote sensing.

Capturing how tree growth and survival vary through space and time is critical to understanding the structure and dynamics of tree-dominated ecosystems. However, characterising demographic processes at scale is inherently challenging, as trees are slow-growing, long-lived and cover vast expanses of land. We used repeat airborne laser scanning data acquired across 25 km2 of semi-arid, old-growth temperate woodland in Western Australia to track the height growth, crown expansion and mortality of 42 213 individual trees over 9 yr. We found that demographic rates are constrained by a combination of tree size, competition and topography. After initially investing in height growth, trees progressively shifted to crown expansion as they grew larger, while mortality risk decreased considerably with size. Across the landscape, both tree growth and survival increased with topographic wetness, resulting in vegetation patterns that are strongly spatially structured. Moreover, biomass gains from woody growth generally outpaced losses from mortality, suggesting these old-growth woodlands remain a net carbon sink in the absence of wildfires. Our study sheds new light on the processes that shape the dynamics and spatial structure of semi-arid woody ecosystems and provides a roadmap for using emerging remote sensing technologies to track tree demography at scale.

Distribution pattern of soil nematode communities along an elevational gradient in arid and semi-arid mountains of Northwest China.

Soil nematodes are the most abundant soil metazoans, occupying multiple trophic levels in the soil food web and playing an important role in soil function. Research on the biogeographic distribution patterns of soil nematode communities and their drivers has received greater attention. However, the distribution characteristics of soil nematode communities along the elevational gradient in the arid and semi-arid regions of Northwest China remain unclear. In this study, four elevational gradients (1750-1900, 1900-2100, 2100-2350 and 2350-2560 m) were established on Luoshan Mountain, Ningxia, an arid and semi-arid region in Northwest China, and soil nematodes in the soil layers of 0-10, 10-20 and 20-40 cm were investigated using the improved Baermann funnel method. The results revealed a monotonically decreasing trend in the total number of soil nematodes along the elevational gradient and soil layer depth, decreasing by 63.32% to 79.94% and 73.59% to 86.90%, respectively, while the interactions were not obvious. A total of 1487 soil nematodes belonging to 27 families and 32 genera were identified across the elevational gradient, with Helicotylenchus as the dominant genus, accounting for 10.43% of the total number of nematodes, and bacterivore nematodes as the main trophic groups, accounting for 32.39% to 52.55% of the relative abundance at each elevation, which increased with increasing elevation. Soil nematode community diversity, richness and maturity indices were relatively low at high elevation and decreased by 44.62%, 48% and 54.74%, respectively, with increasing soil layer depth at high elevations. Compared to low elevations, high-elevation soils experienced greater disturbance, reduced structural complexity and nutrient enrichment of the soil food web, and a shift in soil organic matter decomposition from bacterial to fungal pathways as elevation increased. Finally, redundancy analysis showed that soil pH, bulk density, soil moisture, soil organic carbon, available nitrogen, available phosphorus and available potassium were the main soil factors affecting the composition of soil nematode communities, which well explained the differences in nematode communities at different elevations and soil depths. This study can be used as basic information for further research on soil biota in this mountainous region, expanding our further understanding of the spatial ecology of soil nematodes in the arid and semi-arid mountain ecosystems.

Diversity Patterns of Plant Communities along an Elevational Gradient in Arid and Semi-Arid Mountain Ecosystems in China

Quantitative classification and ordination are instrumental in improving our understanding of plant community patterns and facilitating effective conservation efforts in national mountain ecosystems worldwide. However, there has been a lack of relevant research focused on arid and semi-arid mountain ecosystems. This study aims to address this gap by investigating the Ningxia Helan Mountain National Nature Reserve (located in Northwest China). We conducted a comprehensive study on the patterns of plant communities and their association with environmental factors across a broad elevation range from 1200 m a.s.l. to 2600 m a.s.l. Our findings revealed the presence of 121 angiosperm species across 41 families, with vegetation classified into six distinct groups through two-way indicator species analysis (TWINSPAN) along the elevational gradient. Notably, the communities of Ulmus, Prunus, and Stipa in the middle elevation range exhibited the highest Shannon–Wiener (SW) and Simpson (SN) diversity indices, and these indices followed a single-peak pattern with increasing elevation. Canonical correspondence analysis (CCA) further revealed six distinct yet interrelated plant communities, revealing elevation (ELE) and the biological aridity index (BK) as the most influential environmental factors influencing plant communities’ distribution. This understanding is critically important for biodiversity conservation and the management of ecosystems in arid and semi-arid mountain ecosystems.

A critical review on the active anti-viral metabolites of bioprospecting traditionally used plant species from semi-arid regions of the subcontinent.

Plants are crucial medicinal resources, with 80 % of people relying on them for primary healthcare. The search for natural antiviral compounds is increasing, especially in semi-arid ecosystems where abiotic stress promotes the production of beneficial secondary metabolites. This review highlights semi-arid plants with the potential as functional foods to combat viral diseases and other illnesses. Literature was searched in databases like ScienceDirect to gather information on novel compounds from stress-tolerant semi-arid plant species. These compounds have potential uses in treating viral infections and other health issues such as diabetes and high blood pressure. The review screened 61 semi-arid plants known for their antiviral metabolites. Eight plants were identified with novel antiviral compounds. Key metabolites include agathisflavone, pectic arabinogalactan, azadirachtin, aloin, aloe-emodin, aloesaponarin I, allicin, terpenoids, chlorogenic acids, curcumin, chromones, β-sitosterol, lupeol, oleuropein, carissol, β-amyrin, and ∆-9-tetrahydrocannabinol. Stress-tolerant semi-arid plants are significant sources of metabolites for treating infectious diseases and boosting immune systems. Further research on these metabolites in animal models is needed to verify their efficacy for treating human diseases during endemic and pandemic outbreaks, such as COVID-19.

Assessment of soil carbon dioxide efflux from contrasting land uses in a semi-arid savannah ecosystem, northeastern Ghana (West Africa)

Soil respiration (SR) emits a vast amount of atmospheric carbon dioxide (CO2) and contributes largely to the global greenhouse gas budget. The study assessed the dynamics of SR rates in the Vea catchment in northeastern Ghana, a sparsely gauged semi-arid savannah ecosystem characterized by distinct patterns of soil CO2 efflux. Through field measurements using soil chambers, the study quantified soil CO2 efflux rates in different land use types (woodland, cropland and grazeland), and assessed the influence of soil moisture, temperature, and soil organic carbon stocks on SR variability. The highest soil CO2 fluxes (12.97 ± 0.89 Mg CO2C ha−1 yr−1) were recorded in woodland, followed by grazeland (9.10 ± 0.42 Mg CO2C ha−1 yr−1) with cropland having the lowest rate (5.61 ± 0.29 Mg CO2C ha−1 yr−1). We recorded mean annual soil CO2 flux of 9.23 ± 0.53 Mg CO2C ha−1 yr−1 across the land use types and also observed significant seasonal and spatial variations in SR rates. The highest SR rate (220 mg CO2C m−2h−1) was recorded in the wet months (Jul-Sept and Mar-May) and the lowest rate (30 mg CO2C m−2h−1) in the dry months (Nov-Jan). For the wet season, the mean weekly soil CO2 fluxes ranged between 140 and 160 mg CO2C m−2 hr−1 as opposed to 60–75 mg CO2C m−2 hr−1 for the dry season. Seasonal and spatial variations in SR rates were largely driven by land use type, soil moisture and the interaction of soil temperature and moisture. The results underscore the importance of understanding the emission patterns from various land uses in West African savanna ecosystems to harnessing their potential for climate change mitigation.

A Bibliometric Review of the Impacts of Logging in Forests in Semi-Arid Zones

Forest massifs in semi-arid zones play an essential role in maintaining ecological balances and the livelihood of local communities. However, unsustainable logging in these regions can have devastating ecological, and socio-economic consequences. This bibliometric review aims to synthesize the available evidence regarding the impacts of logging in semi-arid ecosystem. Analysis of publication trends reveals a significant increase in research from 2008, reflecting a growing awareness of the issues related to sustainable forest management. The United States, Canada, Australia and China the most prominent countries in this field. The bibliometric analysis of the highlights major concerns related to climate change, clear-cutting, interactions with demographic dynamics and biogeochemical cycles. However, gaps remain, including a lack of data specific to semi-arid areas, limited understanding of the complex interactions between different dimensions of impacts, and insufficient integration of local perspectives and traditional knowledge. This review highlights the need to continue interdisciplinary and collaborative research efforts to ensure sustainable management of semi-arid forests in the face of current and future environmental challenges.

Unveiling the main drivers of tree decline in Zagros semi-arid forests

Abstract Tree decline in arid and semi-arid forest ecosystems causes severe socioeconomic and ecological problems and thus needs to be thoroughly quantified and monitored across space and time. This study investigates tree and forest decline in Iran’s Zagros forests, considering environmental factors (e.g. topographic, soil, and climatic variables). We used field data from Chaharmahal-and-Bakhtiari (a study area covering 165 km2) and environmental data derived from freely available databases. Relationships between tree, forest decline, and environmental data were analyzed using generalized additive models. Our findings reveal that slope and the BioClim-16 variable (precipitation of the wettest quarter) significantly influence tree decline across various decline classes (P-values: slope = .009, BioClim-16 = .02). The best multivariate model for forest decline incorporated soil organic carbon and silt as predictive variables, with soil organic carbon emerging as the key factor (P-value = .04). Additionally, a spectral analysis of bare soil in declining and non-declining areas consistently demonstrated reduced reflectance values in declining regions across 10 Sentinel-2 bands, with VNIR-3, SWIR-2, red, green, and blue bands consistently showing significant differences as unveiled by the Wilcoxon test in all seasons except winter. These reduced reflectance values may indicate that forests stocked on soils with larger grain size (a higher fraction of sand) and/or higher organic carbon content may be more vulnerable to decline. This study contributes to our hitherto understanding of the main drivers of tree and forest decline in semi-arid forests, among others underscoring the potential utility of the spectral properties of bare soil in sparse semi-arid forests to predict the likelihood of tree decline.

Coupled simulation of percolation and evapotranspiration in semi-mobile and semi-fixed dunes

Accurately describing the important components of the water balance, such as precipitation (P), deep percolation (D), and evapotranspiration (ET) and their relationships is crucial for understanding the water cycle and eco-hydrological processes in arid and semi-arid regions. This study coupled the dual crop coefficient model (Dualkc) with the HYDRUS-1D model to simulate D and ET processes in the semi-mobile and semi-fixed dune ecosystem in China’s Horqin Sandy Land during the growing seasons from 2015 to 2022. The results indicated that the improved HYDRUS-1D model achieved high simulation accuracy at a daily scale, with the R2 of 0.83, RMSE of 0.392, NSE of 0.714, and b of 0.828, representing increases of 15.27%, 20.16%, 16.01%, and 5.6%, respectively, compared to the original model. ET and D constituted the primary water dissipation processes in semi-mobile and semi-fixed dunes, accounting for 97% to 99% of P during the growing season. The evaporative ratio (ET/P) ranged from 46.7% to 79.3%, averaging 65.67% over multiple years, and the deep percolation ratio (D/P) varied between 16.1% and 53%, averaging 31.02%. The distribution of precipitation events, soil water content, and vegetation conditions are critical factors affecting ET and D in arid and semi-arid dune ecosystems. This study is of great significance for a deep understanding of the eco-hydrological processes in the dune ecosystem, and it can provide important support in developing water management strategies in the desertification region.

Protected and Unprotected Areas as Refuges for Bird Conservation in Southeastern Coahuila, Mexico

Information gaps about the distribution of species hamper the evaluation of conservation status and decisions on biodiversity conservation, affecting areas with high species richness and endemism to a greater extent. In this context, carrying out biological inventories in protected and unprotected areas is an important tool to fill these gaps by providing data on the composition, richness, and abundance of species in each locality. The southeastern region of Coahuila (northeast Mexico) is a region where biodiversity research is required, as anthropogenic activities pose a serious threat to the avian diversity of this region. The present study aimed to compare the capacity of protected and unprotected areas to support the richness, abundance, and composition of bird species, as well as providing a list of bird species from eight areas located in this region. The point count method was conducted at the sites, and one-way ANOVA was used to determine the effect of area type on species richness and abundance. Based on our field observations, literature review, and digital databases, the avifauna of these eight areas includes 388 species in 63 families. Of these, 5 species are endemic to Mexico, 6 species are of global conservation concern, and 35 species are of regional conservation concern. The species richness found in this study supports the importance of protected and unprotected areas in southeastern Coahuila. The results of our study highlight the need for further assessment to conserve the avian community, especially considering the increasing threats of anthropogenic disturbance, as well as additional studies that will allow for better characterization of the avifauna of the region. This will help to ensure the conservation of the birds currently threatened by strong anthropic pressure due to the conversion of semiarid ecosystems to agricultural and livestock areas as well as increasing urbanization.

The extinct Notiomastodon platensis (proboscidea, Gomphoteriidae) inhabited mediterranean ecosystems during the Late Pleistocene in north-central Chile (31°S–36°S)

Limited pollen and limnogeological evidence show that central Chile (31°S–36° S) had a more temperate climate during the Late Pleistocene. Questions remain, however, regarding the extent of the mediterranean sclerophyllous forest currently found in this region and its postglacial dynamics. The extinct Notiomastodon platensis was the only proboscidean species that inhabited central Chile and ranged across a broad latitudinal range (31°S–42°S) during the Pleistocene. Although this species was a mixed-feeder, we reconstructed past ecosystems when these animals were alive using stable isotope evidence from dental root collagen (δ13C and δ15N) of N. platensis specimens collected from present-day semi-arid and mediterranean ecosystems in central Chile (31°S–36°S). Compared to modern vegetation isotope baselines, we expected the isotopic value of the Estimated Consumed Diet (ECD) (the probable diet of N. platensis) to be similar to the isotopic signal (low values) from vegetation adapted to temperate rainforests. However, elevated δ15NECD values indicate a paleo-vegetation more similar to a xerophyte scrub influenced by a semi-arid paleoclimate. δ13CECD values reflect a wooded/forested environment but adapted to more arid conditions. Although high δ15N values could be influenced by other non-climatic factors (e.g., grazing effect), our combined evidence suggests that these gomphotheres roamed through ecosystem very similar to those found today in central Chile. Our results show the need for multiproxy reconstructions of past environmental change in Mediterranean regions where the abundance of entomophilous species can lead to biased pollen reconstructions.