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Background and aims Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. We aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. Methods We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix lancina, Rhododendron groenlandicum, and Chamaedaphne calyculata. Results The fine roots of trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Conclusions The dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.

Conservation measures require accurate estimates of density and abundance and population trend assessments. The bonobo ( Pan paniscus ) is considered Endangered in the IUCN Red List. This classification assumes that available population data are representative. However, with only 30% of the bonobo’s historic geographical range surveyed, reliable information is needed to assess the species' population status. Here, we use information from 13 surveys conducted between 2002 and 2018 in an area of 42,000 km 2 , representing ~27% of bonobo-suitable habitat: Salonga National Park and its corridor, Democratic Republic of the Congo (DRC). Using 8310 km of reconnaissance and transect walks and 27,045 days of camera trapping, we: (1) provide updated estimates of bonobo population density and distribution (42,000 km 2 ; ~5,000 km 2 of which, to the best of our knowledge, have not been surveyed before by scientists), (2) assess population trends (15,758 km 2 ; 2002–2008 vs 2012–2018), (3) compare estimates obtained with different methods, and (4) assess the factors driving bonobo density and distribution. Although we detected a non-significant population decline, our study suggests that Salonga is a bonobo stronghold, with a population ranging between 8244 and 18,308 mature individuals (density: 0.31 individuals/km 2 ). Standing crop nest counts returned non-significantly lower density estimates than camera trap distance sampling. Nest count-estimates were higher in areas with Marantaceae understorey and those farther away from rivers, while camera trap-estimates were higher in areas with lower human presence. Regardless of the method, bonobos were rarer in proximity to villages. They occurred more often in areas of dense forest cover and in proximity to ranger posts. Our results point towards a declining bonobo population in Salonga, but do not provide sufficient evidence to confirm this statistically. Consequently, the continued monitoring of the bonobo population and preservation of the integrity of Salonga, considering its biological and cultural heritage, will be crucial in the preservation of this stronghold of wild bonobos.

BackgroundCaloric value is an important indicator of grassland ecosystem function, but the response of caloric value to nitrogen (N) addition and mowing is still unclear. We explored the adaptive changes of plant caloric value and energy standing crop along a N addition gradient after six-year NH4NO3 addition and mowing treatments in an Inner Mongolian temperate meadow steppe in northern China.ResultsWe found that the response of plant caloric value to N addition at different organizational levels was diverse. The caloric value of legumes increased linearly with N addition rates. The caloric value of grasses exhibited a non-linear response trend, initially increasing followed by saturation or decrease, with a N response threshold present. Due to the dominance of grass species, the caloric value at the community level followed a similar pattern to that of the grasses along the N addition gradient. Under mowing, the caloric value of plants at each organizational level increased and usually mowing enhanced the N response threshold. Amongst these, the N response threshold of Leymus chinensis increased from 3.302 to 5.443 g N m−2 yr−1, grasses increased from 4.414 to 5.746 g N m−2 yr−1, and community increased from 5.373 to 9.216 g N m−2 yr−1. Under non-mowing treatment, the N response thresholds of the most dominant species, Leymus chinensis, and community energy standing crop were 10.001 and 15.119 g N m−2 yr−1, respectively. Under mowing, the energy standing crops showed a linear increasing trend.ConclusionsN response thresholds of plant caloric value and energy standing crop vary at different organizational levels (community > functional group > species). The results reveal varying regulatory capabilities of plants on the ecological environment at different organizational levels. These findings enhance our understanding of plant-environment interactions in grassland ecosystems under N deposition from an energy perspective, which is of great significance to clarify the response mechanism of grassland ecosystem structure and function to N deposition.

Increasing human-wild boar conflicts in South Korea have led to a demand for effective management strategies. Absolute abundance, rather than relative indices, is needed for the long-term monitoring and population control of wild boars. Indirect methods for density estimation have become increasingly popular because they are cost-effective and do not have the risk of capture probability bias. We compared three indirect methods, including the non-invasive capture-recapture model (NICRM), random encounter model (REM), and fecal standing crop (FSC), in two different sites characterized by specific habitats (urban and agricultural environments). NICRM and REM reflected population fluctuation and hunting intensity assumptions at both sites; however, FSC did not reflect the latter. While using NICRM, efforts are needed for achieving a low genotyping error rate; this model would achieve more reliable results in low-density areas. REM with accurate parameter information (i.e., daily range, detection zone, and camera placement) could be the most effective density estimation method for long-term monitoring in South Korean environments. Conversely, FSC may not be recommended because of many factors, such as decomposition rate, rainfall, biased distribution of feces that might affect pellet groups. Additionally, the density estimates from this study can provide information for developing effective management strategies in South Korean environments.

Litter is an important component of terrestrial ecosystems and plays a significant role in carbon cycles. Quantifying regional-scale patterns of litter standing crop distribution will improve our understanding of the mechanisms of the terrestrial carbon cycle, and thus enable accurate predictions of the responses of the terrestrial carbon cycle to future climate change. In this study, we aimed to estimate the storage and climatic controlling factors of litter standing crop carbon in the Tibetan Plateau shrublands. We investigated litter standing crop carbon storage and its controlling factors, using a litter survey at 65 shrublands sites across the Tibetan Plateau from 2011–2013. Ordinary least squares regression analyses were conducted to estimate the relationships between litter standing crop carbon, longitude, and latitude. Multiple linear regressions were used to evaluate relationships among litter standing crop carbon, mean annual temperature (MAT), mean annual precipitation (MAP), and aboveground biomass. The litter standing crop carbon storage was 10.93 Tg C, 7.40 Tg C, and 3.53 Tg C in desert shrublands and alpine shrublands, respectively. Litter standing crop carbon decreased with longitude, and was stable with increasing latitude. Most (80%) of the litter standing crop was stored in branches, with only 20% stored in foliage in the shrublands on the Tibetan Plateau. The conversion coefficient was 0.44 for litter standing crop to litter standing crop carbon, and 0.39 and 0.45 for foliage and branch litter standing crop to foliage and branch litter standing crop carbon, respectively. Aboveground biomass can accelerate more inputs of litter and has a positive effect on litter standing crop carbon. MAT had a positive effect on litter standing crop carbon due to stimulating more input of aboveground biomass. However, MAP had a negative relationship with litter standing crop carbon by enhancing litter decomposition.

Information on the pollination ecology and floral visitors of the noxious weed Centaurea solstitialis is available for several populations in its invasive range, but limited information is available in its native range, with most studies conducted on the Greek island of Lesvos. Herein, we document the visitation pattern of bees and explore the relationship of bee body size and nectar availability in weedy populations of C. solstitialis from an urban environment within its native range in northwestern Turkey. Studies were conducted at patches of C. solstitialis in abandoned lots at the Uludağ University near the city of Bursa. A total of 41 species, including honey bees, belonging to five families and 19 genera were recorded. Small megachilid and halictid bee species were the most common visitors. Average nectar standing crop volume per floret was low (0.003–0.117 μL) and did not significantly vary throughout the day. Average bee head width significantly correlated with average nectar standing crop volume but did not significantly change throughout the day. Analyses of pollen loads as well as direct observations of bee foraging behavior indicate that a large number of bees visit C. solstitialis, primarily in search of nectar while carrying a large percentage of pollen grains of this plant species on their bodies. These results are similar to previous observations on a non-weedy population of C. solstitialis from the island of Lesvos.

In a series of dawn-to-dusk studies, we examined the nature and accessibility of nectar rewards for pollinating insects by monitoring insect visits and the secretion rate and standing crop of nectar in the British native plant species Salvia pratensis, Stachys palustris, S. officinalis, Lythrum salicaria, Linaria vulgaris, the non-native Calendula officinalis, Petunia×hybrida, Salvia splendens, and the possibly introduced Saponaria officinalis. We also compared single with double variants ofLotus corniculatus , Saponaria officinalis, Petunia×hybrida andCalendula officinalis . All the British species studied are nectar-rich and are recommended for pollinator-friendly gardens. They showed maximal secretion rates of about 10–90μg sugar per flower h−1, and most had mean standing crops of about 5–60μg sugar per flower. In all British species studied, the corolla was deep enough for the relatively long-tongued bumblebee Bombus pascuorum, but the shallower flowers of Lythrum salicaria were also much visited by shorter-tongued bees and hoverflies, as well as by butterflies. The exotic Salvia splendens, presumably coevolved with hummingbirds in the Neotropics, has such deep flowers that British bees cannot reach the nectar except by crawling down the corolla. With a secretion rate approaching 300μg sugar per flower h−1and little depletion by insects, S. splendens accumulated high standing crops of nectar. S. splendens, and single and double flowers of the two probably moth-pollinated species Petunia×hybrida and Saponaria officinalis, received few daytime visits despite abundant nectar but Calendula was well visited by hoverflies and bees. We compared single and double variants of Lotus corniculatus,Petunia×hybrida and Calendula officinalis, and also Saponaria officinalis, the last being probably introduced in Britain (Stace, 1997 New flora of the British Isles. 2nd edn. Cambridge: Cambridge University Press). In Petunia, Saponaria and Lotus, double flowers secreted little or no nectar. In Calendula, where doubling involved a change in the proportion of disc and ray florets rather than modification of individual flower structure, double and single capitula had similar standing crops of nectar. Except inCalendula , exotic or double flowers were little exploited by insect visitors. In the exotics, this was probably due to the absence or scarcity of coevolved pollinators, coupled, in double flowers, with the absence of nectar.

Background Indigenous cropping systems were often developed with a focus on resilience. For example, farmers in many parts of the world have traditionally grown crop varietal mixtures to mitigate risks of crop failure due to drought, pests, and disease. However, crop varietal mixtures are threatened by policies encouraging farmers to plant homogenous, single-variety cropping systems, which are more vulnerable to increasing climate variability. Teff is one of the indigenous staple crops of Ethiopian origin cultivated throughout the country for multiple purposes. Farmers continue to cultivate diverse varieties of teff, as well as a varietal mixture known as sergegna teff. We assessed farmers’ knowledge and practices related to sergegna teff in the northern highlands of Ethiopia to understand its advantages as well as threats to its continued use. Methods Research was conducted in six kebeles (sub-districts) of Kalu and Tehuledere districts of South Wollo Zone, Ethiopia, situated in warm moist lowlands and tepid and cool mid-highlands. Data were collected through structured surveys with 304 randomly sampled interviewees, semi-structured interviews with 36 purposively sampled key informants, six focus group discussions, guided field tours and market surveys. Varieties of teff in standing crop fields were assessed within 5 m × 5 m random plots at the seed-setting stage. Data analysis included cross-tabulation of survey and interview data, descriptive statistics, and hierarchical clustering. Results Teff dominates the farm fields in the six study kebeles. Altogether, 13 distinct varieties, including farmers’ varieties (landraces) and breeders’ varieties, were recorded. Fifty-three percent of survey respondents reported active cultivation of sergegna teff variety mixtures. The same proportion asserted preference for varietal mixtures over pure brown or white varieties on account of nutritional benefits and non-food domestic functions. The varietal mixture was also top-ranked by key informants for drought and disease resistance, resilience, and ecological elasticity. Households reported utilizing the varietal mixture in various types of food and selling at local markets. Most respondents (53% of those who reported cultivating sergegna teff in 2023) indicated using sergegna teff to prepare leavened and unleavened foods, including injera, dimeso, kita, anebabero, serebat , porridge and gruel. Conclusion Farmers express that the ongoing cultivation and use of sergegna teff boost production and enhance resilience and economic returns. These perspectives should be considered in initiatives promoting single breeder’s varieties, which risk supplanting traditional crop varietal mixtures. Further study, alongside proactive conservation, and scaled-up efforts of institutions concerned with food security, biodiversity conservation, and inclusion of ILK are needed.

Aim: Root production and turnover play a key role in regulating carbon (C) flow in terrestrial ecosystems. However, a general pattern reflecting the responses of roots to increasing nitrogen (N) input has yet to be described. Location: Global terrestrial ecosystems. Methods: We conducted a meta-analysis to assess the central tendencies of root production, turnover rate and standing crop with respect to the experimental addition of N. We evaluated the effect of the form of N, root diameter and climatic (mean annual temperature, MAT; mean annual precipitation, MAP), biotic (ecosystem type, plant type and forest stand age) and forcing factors (experimental duration, N addition rate and cumulative amount of N) on the variations in root response. Results: Globally, the addition of N significantly decreased root production and turnover rate but had only a minor impact on root standing crop. In different ecosystems, the three root variables exhibited heterogeneous responses to N enrichment. Additionally, root production and turnover rate responded distinctly to diverse forms of N. The responses of root production and turnover rate to the addition of N were generally positively correlated with MAT and MAP but negatively related to forest stand age and experimental duration. The response pattern of root standing crop was negatively affected by MAT, MAP and forest stand age. However, none of the three root parameters had any obvious correlations with N addition rate or cumulative amount of N. Main conclusions: Our results demonstrate that, on aggregate, the addition of N decreased root production and turnover rate at the global scale. These root response patterns and the regulatory factors can be incorporated into earth system models to improve the prediction of belowground C dynamics.

The way in which flower visitors share floral resources or compete for them throughout the day is a decisive factor for the effectiveness of pollination. We described daily rhythms of flower visitation by bee species and tested whether such patterns depend on: (1) the body size of the species, (2) the daily patterns of variation in weather and nectar standing crop, and (3) the effects of weather on the daily rhythm of variation in nectar standing crop. After 1 year of biweekly samplings, we encountered 56 bee species visiting basil flowers. Larger bee species were more active in the cooler and more humid hours of the morning. Smaller species foraged later, during the warmer and drier hours. Throughout the day, nectar volume decreased. In the laboratory, we determined a positive effect of increase in temperature on nectar volume, unlike the negative correlation recorded in the field. Nectar volume decreased in plants under experimental drought, showing similarity with the driest hours of the day. The daily cycle of temperature is the fundamental factor that, directly and indirectly, via air humidity, soil moisture, and nectar supply, influences bee activity according to body size and physiological attributes. In the field, the positive effect of increasing temperatures on nectar volume is masked by a stronger, negative effect of decreasing air humidity and soil moisture throughout the day.