Riparian forest loss and various land use impacts on macroinvertebrate communities in Nigerian streams remain poorly understudied. To fill this knowledge gap, a study was conducted on five streams in the southwest ecoregion of Nigeria between December 2019 and October 2021. A total of 2,077 macroinvertebrates were sampled, comprising 16 orders, 40 families, and 80 species. Aquatic insects were the most abundant, constituting 85 % of species and 73.13 % of individuals. Other specimens included Mollusca, Crustacea, Arachnida, and Annelida. Notably, Olumirin stream exhibited the highest macroinvertebrate abundance, including the stress-sensitive Ephemeroptera-Plecoptera-Trichoptera (EPT) members. The site also had the highest degree of naturalness, widest channel and dissolved oxygen (DO), but lowest electrical conductivity (EC) and total dissolved solids (TDS) compared to the other streams (Abirunmu, Awoosun, Mogimogi, and Aboto), that harbored facultative and stress-tolerant species, indicating varying degrees of disturbances. The bivariate regression analysis confirms that riparian deforestation and land use impact macroinvertebrate distribution in streams as there was an inverse relationship between EPT abundance and forest cover. Also, DO positively correlates with EPT taxa richness but inversely correlates with Coleoptera richness and Hemiptera abundance. As a result, Olumirin stream is proposed as a benchmark for evaluating freshwater ecological integrity in the region. Given the escalating anthropogenic activities in the tropics, urgent collaborative efforts are required to safeguard freshwater biodiversity, protect the riparian corridor of Olumirin stream, and restore impaired streams in the region.
Intense human activities have altered the land use/land cover (LULC) patterns of lake basins, posing a major challenge to ecosystem sustainability. However, the impacts of land use/cover changes (LUCCs) on ecosystem service value (ESV) of lake basins remain unclear. Here, we investigated ESV of the Baiyangdian (BYD) region from 1980 to 2020 based on value equivalent method, assessed spatial differences of ESVs using hot/cold-spot mapping method, and explored the impact of LUCCs on ESVs in combination with elasticity coefficients. The results showed that (1) the study area was dominated by marsh (50.53 %), water bodies (21.84 %) and cropland (20.28 %) in 2020. Marsh, forestland and grassland significantly decreased from 1980 to 2010, and cropland rapidly rose reaching a peak. Marsh, grassland and water bodies increased during 2010–2020, while cropland decreased. (2) Total ESV was 3469.14 million yuan in 2020, a decrease of 5.77 % compared to 1980 (3681.41 million yuan), mainly due to the decrease in marsh area. (3) ESV hot spots were mainly distributed in the middle part of the region, consistent with water bodies, and ESV cold spots were mainly distributed on the edges of the region, consistent with cropland. The spatial distribution of ESVs varied widely, with an increasing trend. (4) The elasticity coefficients of ESVs to LULC were all greater than 1, indicating that ESVs responded significantly to LUCCs. Overall, there was a strong temporal and spatial correlation between LULC and ESV. This study will provide valuable references for optimizing land use policies and ecological restoration plans and promoting the improvement of ESVs in shallow lakes.
Understanding plant water consumption is crucial for artificial afforestation under drought environments and water stress in desert regions. However, the water consumption characteristics of desert species responding to the irrigation regimes are often neglected. By conducting a field test in the Taklimakan Desert Highway shelterbelt, this study examines the sap flow traits of two typical woody halophyte species (Calligonum mongolicum and Haloxylon ammodendron) and how they react to weather conditions and watering practices. Under the same irrigation treatment, the stem flux of C. mongolicum on sunny days was 1.5–5.3 times that on dusty days, while the stem flux of H. ammodendron on sunny days was 3.5–5.5 times that on dusty days. Both species demonstrated some sap flow during the night, representing 14.3%–24.9% and 7.3%–10.4% of the total sap flow for C. mongolicum and H. ammodendron, respectively. H. ammodendron maintained a higher stem flow during daytime and was more drought resistant than C. mongolicum. The daily sap flow patterns of these two species varied, showing both ‘single’ and ‘double peak’ curves depending on the watering conditions. A delay was also observed between the sap flow of these two species and the environmental factors. The factors influencing plant sap flow were found to be in the order of solar radiation, temperature, relative humidity, and saturated water vapor pressure difference. A BP-neural network proved highly effective for accurately simulating the sap flow of these two species. This research provides insights into how two common desert tree species adapt their water use in response to drought conditions, which is vital for artificial forest creation in desert areas.
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