Native Rangeland Research Articles

Suppression of Potentilla recta by targeted goat grazing and aminopyralid on northern intermountain rangelands

AbstractSulphur cinquefoil (Potentilla recta L.) is an invasive perennial forb threatening rangelands in western North America. To identify best management strategies to control P. recta, we examined targeted goat (Capra hircus L.) grazing conducted once (pre-flowering) versus twice (pre-flowering and flowering and seed set), aminopyralid application, and integrated targeted grazing and aminopyralid as management strategies. We also examined the interaction between treatments and seasonality (spring and summer) and explored the possibility of off-target effects to non-target species. Two intermountain rangelands in British Columbia, Canada, were treated, one with targeted grazing treatments only and one with targeted grazing and herbicide treatments. Targeted grazing treatments were implemented in 2019 and 2020, and aminopyralid was applied once in 2019 at a rate of 56 g ai ha−1. Potentilla recta aboveground biomass and number of seed heads declined following targeted grazing treatments at both field sites in 2019 and 2020 when compared with the control, with no differences between targeted grazing treatments. In May 2020, before the implementation of targeted grazing for the second year, a decrease in P. recta biomass was not measured in the targeted grazing treatments, but biomass was 87% to 99% less in the herbicide-only and targeted grazing plus herbicide treatments. In July 2020, declines in biomass and seed heads in the herbicide-only and targeted grazing plus herbicide treatments did not differ from grazing twice, and aminopyralid effects did not differ among the three herbicide treatments. Further research is required to examine legacy effects of targeted goat grazing and aminopyralid on P. recta, establish reapplication frequency of treatments, and determine whether integrating targeted goat grazing and aminopyralid is needed in the long term to manage P. recta. A long-term study is also needed to examine off-target effects from targeted goat grazing and aminopyralid and ways to mitigate these effects to promote healthy native rangeland plant communities.

Impact of Land Use Pattern on Rangeland Vegetation in Blue Nile State, Sudan

The study was conducted in‘Elrosieris’area, Blue Nile State, Sudan, at the end of autumn season on Novermber, 2018 to investigate the impact of land use type on natural rangelands vegetation. Two sites were selected; namely rangelands and abandoned croplands. Three transects of 100 m length were placed randomly in each of these sites. Species composition,plants cover and ground cover were determined using Parker loop method along these transects. Plant density (Plant/m2), frequency, biomass productivity (ton/ha) and carrying capacity, Tropical Livestock Unit (TLU/ha/yr) were determined using quadrate method applied along these transects. The data were analyzed using descriptive statistic and T- test. Theresults revealed that plant cover was higher in rangeland (87%) compared to abandoned cropland (79%). Bare soil was lower in rangeland (4%) than in abandoned cropland (8%). Pennisetum ramsum was dominant species inrangeland (70.67%) and less so in abandoned cropland (25.33%). Plant density was higher in rangeland (34.67 plant/m2) compared to abandoned cropland (11.58 plant/m2). The difference in productivity and carryingcapacity were very slight. The study concluded that Pennisetum ramsum was dominant in terms of cover and composition regardless of land use type. Plant density was better in rangeland. The differences in yield and carryingcapacity were close regarding land use pattern.

Assessment of Soil Redistribution Following Land Rehabilitation with an Apple Orchard in Hilly Regions of Central Iran

This study was executed to explore soil redistribution and soil quality changes induced by land degradation and then rehabilitation by orchard plantation in different slope positions in a semi-arid region in central Iran. A total of 72 surface soil samples (0–30 cm) were collected from three land uses (natural rangelands, dryland farming, and apple orchards) in four slope positions (shoulder, backslope, footslope, and toeslope). The soil physicochemical properties and magnetic parameters were measured, and soil redistribution was determined in the selected soil samples using the 137Cs technique. The results showed that rangeland degradation and, subsequently, rainfed cultivation, led to a significant decline in the soil quality indicators, such as soil organic matter (SOM), total nitrogen (TN), available potassium (Kava), and available phosphorous (Pava), thus incurring further soil loss, as determined by the 137Cs technique. Conversely, the conversion and rehabilitation of drylands to apple orchards cultivated on the contour terraces improved soil quality significantly and decreased soil loss (p < 0.05) and soil quality grade (p < 0.01). Additionally, the findings indicated that slope positions relative to land use change had a reasonable impact on the variability of soil properties and soil loss and deposition. The results of 137Cs analysis showed that the drylands had the highest soil loss (185.3 t ha−1 yr−1) and maximum sedimentation (182. 5 t ha−1 yr−1) in the shoulder and footslope positions, respectively. The random forest model applied between 137Cs inventory and soil properties indicated that calcium carbonate equivalent (CCE), TN, Pava, Kava, and bulk density (ρb) could explain 75% of the total variability in 137Cs inventory with high R2 (0.94) and low RMSE (111.29). Magnetic measurements have shown great potential as a cost-effective and fast method for assessing soil redistribution in hilly regions, as confirmed by the findings of the 137Cs analysis, which agreed well with the magnetic susceptibility at low frequency (χlf). Overall, the results confirmed that restoring abandoned dryland by orchard cultivation may improve soil quality and diminish soil loss in the semi-arid region of Iran. However, further research is required to assess other aspects of the ecosystem affected by this restoration.

Forage resources and animals’ feeding in southern groudnut bassin and eastern regions of Senegal

Rainfall disturbances, a consequence of the effects of climate change, aggravated by anthropogenic pressure on vegetation, are leading to the progressive disappearance of several adapted local plant species in the so-called "groundnut basin" and eastern Senegal. Also, the clearing of land for agriculture potentiates and amplifies this degradation. At this rate, the loss of most of the local plant, forage and forest resources will follow. As part of a multi-species census and collection of plant genetic resources for food and agriculture, an inventory of available forage resources in the groundnut basin and eastern Senegal was made. This inventory was made by field observations triangulated with interview data. The results show that the methods and level of exploitation of natural forage resources and crop residues differ from one area to another. The natural rangeland, which still constitutes the essential part of domestic ruminants feed in these regions, is in continuous degradation. In fact, this rangeland in groundnut basin is not very diversified like southern area, with a low index of quality and volume of pastures. Crop residues are abundant but not very varied. They represent an interest for the breeders of this zone and their sale prices can sometimes exceed those of the harvested products. This is a snapshot of the situation, valid for a given time. This situation is dynamic and can change significantly from one moment to the next. Nevertheless, the results obtained will make it possible to conceive methods of conservation and production of the identified species; in order to identify the best methods of management and sustainable use.

An Important Forage Source for Animals: Small Grain Pastures

An approximate 40-65% of the qualified roughage needs of farm animals in Turkey can be met according to different calculations. Natural rangelands are important sources in this regard. However, there are serious problems in the management of these areas. Particularly, untimely and heavy grazing is one of the main reasons for the deterioration of vegetative cover. Grain pastures are one of the best options for both reducing the qualified roughage deficit as well as in the solution of certain problems related to grazing in rangelands. Grass yield and quality of cool climate cereals are high, and they reach grazing maturity before natural rangelands in spring, then they can be grazed until later in fall and even could be used as winter rangeland in regions with cool winters. They can also be used for double production (grass + grain). In this respect, the importance and potential of grain pastures in the rangeland-based livestock system have been evaluated in this paper.

Research, development and adoption for the north Australian beef cattle breeding industry: an analysis of needs and gaps

This review seeks to analyse and prioritise needs and gaps in research and development (R&D) for the north Australian beef cattle breeding industry, and to advise on options to increase rates of adoption and successful implementation of this R&D. The material reviewed includes the peer-reviewed literature as well as industry reports and other relevant publications in three targeted areas of R&D deemed to be important by industry leaders and supporting scientists: (i) breeding herd management, (ii) feedbase management, and (iii) management of environmental sustainability. For breeding herd management, the need for uniform definition and consistent utilisation of appropriate productivity metrics is highlighted, with emphasis on assessment of maternal reproductive efficiency in terms of weaning (or branding) rates. Priority is given to the urgent need for reliable means of remotely assessing causes of neonatal calf mortality to enable the development and application of management interventions that improve calf survival rates. The highest priority for feedbase management is to increase producer awareness and willingness to adopt stocking rates that are appropriately matched to the long-term carrying capacity of native rangeland pastures that predominate in northern Australia. Other opportunities include increasing the use of perennial, tropically adapted legumes, where conditions permit, to improve soil fertility and nitrogen intake of cattle, and devising strategies to overcome widespread phosphorus deficiency through diagnosis and supplementation, especially in the wet season. In order to enhance environmental sustainability in the face of climate change, priorities include improving producer awareness and use of increasingly robust tools for predicting key weather events, as well as developing genetic strategies to increase heat tolerance of cattle and evaluating management interventions to mitigate heat stress. Conclusions drawn from these sections are summarised and used to make recommendations on priorities for increasing adoption of existing research-proven practices and technologies, and for further R&D on selected topics.

Vegetation and Animal Production in Pastures Sprayed for Western Ragweed Control

Western ragweed (Ambrosia psilostachya) is a common native forb found throughout Kansas native rangelands and in some seeded pastures. Over time, western ragweed can form dense colonies from growth of lateral creeping rootstalks with multiple buds that can initiate new growth and form an upright stem and plant. Past research has shown that western ragweed does not compete with native grass production until ragweed contributes over approximately 35% of the forage dry matter of a pasture area. Cattle have utilized western ragweed in past long-term historical grazing trials. In a previous long-term trial at Hays, KS, western ragweed was the most common forb found in light and moderately stocked pastures. Frequency of western ragweed was greatest in pastures with light stocking rates, and frequency of western ragweed declined by nearly 50% in moderately stocked pastures because animals utilized the western ragweed. In heavy stocking rate pastures, western ragweed was found in only trace amounts because of greater animal use. However, producers still question if cattle utilize western ragweed and achieve adequate gains in pastures with high western ragweed populations. Therefore, we conducted a grazing trial to determine if controlling western ragweed in pasture improved stocker animal gains compared to pastures with no ragweed control.

Combining Rainwater Harvesting and Grass Reseeding to Revegetate Denuded African Semi-arid Landscapes

In African drylands, perennial grasses preferred by grazing livestock are disappearing at an alarming rate. This has led to recurrent livestock feed shortages threatening pastoralist’s livelihoods. Combining native grass reseeding and rainwater harvesting offers a viable and innovative solution to reverse this trend. However, studies to determine how biomass yields are affected by soil moisture availability attributed to in situ rainwater harvesting in African drylands are limited. We investigated how biomass yields of three grasses native to Africa, i.e., Enteropogon macrostachyus (Bush rye grass), Cenchrus ciliaris (African foxtail grass), and Eragrostis superba (Maasai love grass), are affected by soil moisture content in a typical semi-arid landscape. Rainwater harvesting structures included trenches, micro-catchments and furrows. Additionally, rain runoff was diverted from an adjacent road used as a catchment area. Soil moisture was measured between November 2018 and August 2019 using PlantCare Mini-Logger sensors installed at 40 and 50 cm depths and 0, 1, 5 and 15 m away from the trench. Quadrat method was used to determine biomass yields in August 2019. Peaks in soil moisture were observed after rainfall events. Soil moisture content gradually decreased after the rainy season, but was higher closer to the trench. This is attributed to the prolonged rainwater retention in the trenches. Biomass yields were in the order Eragrostis superba > Cenchrus ciliaris > Enteropogon macrostachyus. Biomass production was higher near the trenches for all the studied species. Sensitivity to soil moisture demonstrated by the magnitude to yield reduction during the growing season was in the order Eragrostis superba > Cenchrus ciliaris > Enteropogon macrostachyus. These results suggest that Eragrostis superba is more sensitive to drought stress than Enteropogon macrostachyus that is adapted to a wide range of soil moisture conditions. We demonstrated that in situ rainwater harvesting structures enhanced soil moisture availability and displayed great potential for revegetating denuded natural rangelands in semi-arid African landscapes. Thus, combining rainwater harvesting and reseeding techniques can produce measurable improvements in pastoral livelihoods and should be incorporated in dryland development policies in the region. Ultimately, incorporating such innovative strategies can strengthen the effectiveness of ecological restoration in African drylands to meet the objectives of the UN Decade on Ecosystem Restoration and achieving the UN Sustainable Development Goals.Graphical abstract

Ensilage potential and nutritional value of Columbus grass (Sorghum almum Parodi) at different phenology and storage duration in the derived savanna zone of Nigeria

AbstractInsufficient forage supply from natural rangelands during the dry season hampers ruminants' performance in the derived savanna zone of Nigeria. Therefore, to provide alternative feed resources, we evaluated silage potential of Columbus grass (Sorghum almum Parodi) at boot, dough and maturity stages for 4‐, 8‐, 12‐ and 16‐week ensiling durations, in a 3 × 4 factorial experiment. The dry matter yield (DMY) was determined at each harvest stage, and the forages were subsequently ensiled. The results revealed that the DMY of S. almum at maturity was 8.98% and 18.67% higher than at dough and boot stages, respectively (p < 0.05). The silages were ranked “good silage” based on physical characteristics. Silage pH decreased with advancing ensiling duration from 4 to 16 weeks in boot (5.25–4.63), dough (5.63–4.11) and maturity (5.42–4.91), with a corresponding increase in lactic and volatile fatty acids. Crude protein (CP) was higher in forages ensiled at maturity and increased with ensiling duration after initial decline from 4 to 8 weeks. Neutral detergent fiber (NDF) and hemicellulose increased quadratically from boot to dough and subsequently declined at maturity. Growth stage, ensiling duration and their interactions influenced the macrominerals' content (p < 0.05). Silages' dry matter intake (DMI) declined from boot to dough stage across the ensiling durations, and except for 8 weeks, the DMI increased at maturity by 6.71%, 5.54% and 7.19% in 4, 12 and 16 weeks, respectively. Therefore, owing to the lower NDF and high DMY, CP and DMI of S. almum ensiled at maturity for 16 weeks, it could guarantee a quantitative and qualitative forage supply to maintain optimum animal performance throughout the dry season.

Carbon dynamics and soil greenhouse fluxes in a Florida's native rangeland before and after fire

Grazing lands, including the native rangelands, cover an extensive area of the southeastern United States, representing an important component of the carbon balance for the region. In Florida, native rangelands extend over 3.1 Mha, experiencing a natural fire frequency between 2 – 5 years and a strong climatic variability. Management includes prescribed fire and mechanical brush control. This study is the first of its kind assessing the impacts of prescribed fire and climatic variability on C dynamics and warming potential in Florida's rangeland. We used a combination of eddy covariance and chamber measurements to estimate net ecosystem C exchange (NEE), greenhouse gas (GHG, CO2, CH4, and N2O) emissions, and C in pre and post-fire aboveground biomass. NEE measurements extended four and a half years since 2016, included a fire event during the fourth year (May 1st, 2019), and two and a half years of GHG measurements . Pre-fire net ecosystem production (NEP) was -368 ± 41 g C m−2 yr−1 and decreased to -181 g C m−2 yr−1 during fire year. After accounting for fire C emissions, net ecosystem C balance was -43 g C m−2 yr−1 in 2019. Soil CO2 dominated GHG emissions increasing 172 g C m−2 yr−1 after fire, N2O fluxes increased from 29, pre-fire year, to 41 g m−2 yr−1 (CO2eqv) post-fire, the ecosystem was a CH4 sink between -1.7 and -3.9 g m−2 yr−1 CO2eqv. The fire effect on C uptake was short-lived, the ecosystem recovered fast after fire, NEP reached pre-fire monthly average two months after, increases in warming potential caused by fire were offset within the next year after. The Florida's rangeland is a suitable ecosystem to mitigate global warming, it acted as a strong C sink offsetting -1148 g C m−2 in four years including a drought and a fire year.

Short duration overnight cattle kraaling in natural rangelands leads to increased tree damage by elephants

AbstractElephants are attracted to nutrient hotspots created through short duration overnight cattle corralling (hereafter kraaling) in natural rangelands at Debshan, a mixed cattle-wildlife private ranch in central Zimbabwe, causing severe tree damage. We determined the effect of age of nutrient hotspot (i.e., time after kraal use) on elephant use and the extent of tree damage. Elephant use and tree damage were assessed in nutrient hotspots of varying ages (6, 12, 24, 36 and 48 months after kraal use) and in surrounding landscape. We also compared Acacia karroo bark nutrient and soil nutrient concentration between nutrient hotspots (24 months after kraal use) and the surrounding landscape. Elephant use of nutrient hotspots was highest at 12 and 24 months after kraaling. The most severely damaged trees were in the 12-, 24- and 36-month-old nutrient hotspots. Acacia karroo bark nutrient concentrations (nitrogen, potassium, calcium, magnesium and iron) were higher in nutrient hotspots than surrounding vegetation, while soil nutrients (nitrogen, phosphorus, calcium and potassium) were higher in nutrient hotspots than surrounding landscape. We concluded that elephants mostly used nutrient hotspots 12 and 24 months after kraaling, while severe tree damage occurred 12, 24 and 36 months after kraal use.

Habitat Types Effect on Diversity, Distribution and Abundance of Dung Beetles

Dung beetles are ecologically important taxa to study the assessment of habitat modification and disturbance across the globe. This study was aimed to explore community composition, species richness and abundance of dung beetles in response to Gujrat, Punjab, Pakistan. Dung beetle assemblage were sampled from four habitat (natural rangeland, cropland, roadside and housing colonies) during 2014-2016 by placing pitfall traps baited with cattle dung. A total number of 540 specimens representing 17 species belonging to seven genera and four tribes were collected. We calculated species relative abundance in natural habitat (34.8%), cropland habitat (40.4%) and in road side areas (25.2%) was recorded, whereas no specimens were recorded in urban areas. Aphodius contaminatus (42.96%) was the most abundant species followed by Onitis castaneous (26.29%) and Onitis singhalensis (20.74%). Tunnellers (50.58%) and dwellers (49.01%) were dominant in all habitats, whereas rollers were least abundant (1.37%). The values of Shannon-Wiener (H) diversity and evenness (E) showed variations among different habitats i.e. natural habitat (H=1.20; E=0.55), cropland habitat (H=1.41, E=0.32) and roads-side (H=0.80, E=0.37). The study showed that cropland served as a major habitat for dung beetles due to its uniformity and close association with mammalian fauna. The results emphasized that natural habitats within the agro-ecosystem have become isolated and fragmented habitat with lesser stability and low resources thus resulting into less diverse habitat. Roadside areas are in close proximity with cropland and act as corridors for efficient species flow within ecosystem due to cattle movement through these areas.
 
 

Salt Cedar Intake by Cattle, Sheep, and Goats Following 21 Days of Exposure

Salt cedar (Tamarix spp. L), is found across Texas and the western United States, primarily near riparian areas. Introduced in the 1800s as an ornamental plant, salt cedar escaped domestic gardens, invading native rangelands. Mechanical and chemical control options for salt cedar are available, but effective control can be difficult and cost prohibitive. Sheep and goats will readily consume salt cedar after exposure at weaning, and goats readily consume the plant when released on rangelands. Unfortunately, sheep and goats are not a viable option in many areas due to predation or lack of appropriate fencing. The objectives of this study were to determine if cattle would consume salt cedar at a similar level (body weight basis) as sheep and goats and to determine if preconditioning improved acceptance of salt cedar by cattle. Angus-Hereford cross heifers (n = 15), Rambouillet lambs (n = 15), and Boer-Spanish cross kids (n = 15) were placed in individual pens for 21 d and fed salt cedar leaves and tender stems daily. For the first 21 d, eight head from each species were fed a basal diet and salt cedar while 7 head only received the basal diet. The amount of salt cedar in the diet was increased from 5% of the diet to 10% of the diet after 7 d of feeding and fed until d 21. From d 22 to 28 both naïve and familiar animals were fed salt cedar daily. All animals readily increased intake of salt cedar. By d 7, cattle, sheep, and goats consumed the plant, but intake varied daily for cattle and sheep. After the first 7 d, goats consistently ate more (P < 0.05) salt cedar than cattle or sheep. While goats may consume more salt cedar, cattle may be a viable option to reduce salt cedar cover when goats are not a viable option.

Achieving dietary micronutrient adequacy in a finite world

Achieving dietary micronutrient adequacy in a finite world

Evaluation of Total Roughage Production and its Sufficiency for Livestock in Turkey

In this study, total roughage production and its sufficiency for farm animals in Turkey was evaluated. Because of insufficient production, feed prices are relatively high and fluctuating in Turkey. It was estimated that, the total 40 363 210 tonnes of roughages production in Turkey was supplied by meadows and pastures (13 164 210 tonnes), shrublands (11 267 000 tonnes) and forage crops production (15 932 000 tonnes). In addition, total straw and stubble production was estimated as 31 074 800 tonnes for animal feed, indicating that half of the total roughages production in Turkey came from straw and stubble production. In Turkey, the large and small ruminant stock is composed of a total of 17 066 900 animal units and in order to meet only the maintenance requirements of these animals via roughage, 77 867 731 tons of roughage is needed in 2019. Considering the daily dry roughage requirement as 12.5 kg (approximately 2.5 percent of total 500 kg live weight), deficiency of daily feed amount was estimated as 1.032 kg per animal unit and a total of 6 429 720 tonnes in 2019 in Turkey. If shrublands, straw and stubble production is neglected or removed from the calculation, then total deficiency reaches at 48 771 521 tonnes year-1 (62.63% of the total feed requirement). For a rational animal feeding, not only the maintenance requirements of the animals but also, in addition to their maintenance requirements, at least 5-7 kg of milk production requires meeting from quality roughages. In this case, it is clear that the need for roughage will increase more. In Turkey, suffering from roughage shortage that adversely affecting production obtained from small and large ruminants, high quality forage production should be, at least, doubled by using every possible resource including natural rangelands, fallows, and cultivated lands effectively without compromising soil conservation and feed costs principles.

The effect of rangeland quality on the mohair quality of Angora goats fed on the natural rangelands

The aim of this study is to determine the effect of the rangeland quality of Ankara goats fed on some natural rangeland in Ankara on the mohair quality. The research was carried out in 3 different quality natural rangelands in Ankara province. Crude protein, ether extract, Ca, Fe, N, energy contents and digestibility, in vitro gas production, and relative feed values of good quality rangeland plants were the highest compared to other rangelands, but the crude fiber, acid detergent fiber, and neutral detergent fiber were the lowest (p < 0.05). In the study were used a total of 120 animals (20 males, 20 females in each farm) from 3 farms where Angora goats are raised in the region of rangelands. The mohair quality was determined in mohair samples taken from 6 month old, 1.5, and 2.5-yearold animals. Rangeland quality significantly affected mohair lengths, fineness, elasticity, tenacity, and clean mohair yield, in males and females (p < 0.05). The highest values were obtained from goats fed good quality rangeland (p < 0.05). The effect of age on these features was also important. The mohair quality (length, elasticity, tenacity) increased with increasing age (p < 0.05). The effect of the rangeland quality on the nozzle number was not significant, but the effect of age was significant. and, the nozzles number increased with increasing age. The nozzle depth was affected by the rangeland quality and age. The nozzle depth has increased due to the increase in rangeland quality and age. While the mohair Ca, Mg, S, Fe, and N content of male and female goats were higher in goats fed on good quality rangeland, these were lower in goats fed low-quality rangeland (p < 0.05). While mohair Na content positively affected rangeland quality in females (p < 0.01), was insignificant in males.

Seasonal patterns of forage quality in six native forb species

The forage value of native forbs is rarely considered in pasture mixtures, even though such species can make up a substantial proportion of the diet of cattle on native rangelands. Incorporating non-leguminous forbs into pasture grazing systems can provide additional ecosystem services such as pollination habitat, and ideally those forbs would also provide some forage value. We therefore assessed the seasonal variation in protein and fiber [neutral detergent fiber (NDF) and acid detergent fiber (ADF)] content of six common western Canadian native forb and sub-shrub species: yarrow (Achillea millefolium), smooth aster (Symphyotricum laeve), prairie crocus (Pulsatilla patens), prairie rose (Rosa arkansana), Canada goldenrod (Solidago canadensis), and American vetch (Vicia americana). The legume V. americana displayed the highest protein followed by S. canadensis and S. laeve. V. americana also has the highest fiber concentration through the growing season. S. canadensis and S. laeve had lower fiber content; thus, making them a good choice for addition in seed mixes to meet the energy and nutrient requirements of cattle. Forb protein and fiber content showed opposite trends during the growing season. Crude protein decreased while NDF and ADF increased as a general pattern tied to physiological stage and degree of senescence. The promising nutritional profile of some forb species suggests that these species should be considered in pasture mixes.

Species co‐occurrence shapes spatial variability in plant diversity–biomass relationships in natural rangelands under different grazing intensities

AbstractGrazing can alter plant species interactions in natural rangelands, which in turn might influence the productivity of the ecosystem but we do not fully understand how spatial variability in plant diversity‐biomass relationships are modulated by grazing intensity. Here, we hypothesized that plant species co‐occurrence in rangelands is mainly driven by niche segregation due to grazing and heterogeneity in local resources, and that grazing, therefore, modulates diversity–biomass relationships. We tested our hypothesis across 35 rangeland sites in Iran, using a species co‐occurrence index to assess plant spatial aggregation within each site. At each site, we measured aboveground biomass, plant diversity, topography, soil nutrients, and three levels of grazing intensity. High spatial segregation of plant communities (low species co‐occurrence) was found at heavily grazed sites, whereas greater spatial aggregation (high species co‐occurrence) was found on low and moderate grazed sites, showing varied associational patterns of species with grazing intensity. Soil nutrients increased with grazing intensity and spatial segregation of plant communities was greater at sites with high soil nutrient concentrations, indicating that grazing intensity influences the spatial heterogeneity of plant communities via nutrients deposited in urine and feces. Declining plant biomass with grazing intensity was related to a strong decline in graminoid species diversity, which suggests that the diversity‐biomass relationship is influenced by selective grazing of palatable species. The relationships between species co‐occurrence and biomass or plant diversity suggest non‐random patterns in species co‐occurrences with grazing intensity, which could be the result of competition driven by high livestock grazing intensity. We, therefore, suggest that rangeland stocking rates should be managed properly to maintain rangeland production while promoting plant diversity.

Note on Effect of Sulfuric Acid on Breaking Seed Dormancy of Least snout Bean (Rynchosia minima L.)

Least snout bean (Rynchosia minima L.) is considered a promising rangeland legume fodder for marginal land in Sudan, but its seeds are associated with high dormancy (%). This study was carried out at the Laboratory of the Plant physiology, Department of Botany and Agricultural Biotechnology, Faculty of Agriculture, University of Khartoum to investigate the effect of sulfuric acid (H2SO4) on breaking seeds dormancy of least snout bean. The seeds were soaked in 0, 50, 70, and 100% H2SO4 concentrations for 30, 45, 60, 90 and 120 minutes. The seeds were germinated in petri dishes and incubated at room temperature for 10 days. The H2SO4 concentration and soaking period significantly (P &lt; 0.01) increased seeds germination (%) and decreased mean germination time (MGT). The germination percentage was increased while MGT was decreased by increasing soaking period up to 60 min. The highest germination (%) and lowest MGT were obtained by soaking the seeds in 70 % H2SO4 for 60 minutes. The result would be useful for large-scale establishment of least snout bean in natural rangelands.

Seed germination dynamics of silverleaf nightshade (Solanum elaeagnifolium Cav.) and implications for effective weed management

AbstractSilverleaf nightshade (Solanum elaeagnifolium Cav.) is a noxious weed that threatens agricultural productivity and biodiversity worldwide. The long‐term management of soil seedbanks along with the aboveground populations of silverleaf nightshade has the potential to effectively control the species in its introduced range. Implementation of this strategy requires insights into the germination behavior of the weed in response to various environmental stimuli and endogenous cues. We assessed the morphology and germination of silverleaf nightshade seeds from an agricultural farm, native rangelands, and an urban site in Texas, USA. The effects of growth substrate, phytohormones, and salt treatments on seed germination were also evaluated to identify potential stimulus that can be used to manipulate germination in the species. Results of the study showed that silverleaf nightshade seeds from the agricultural farm were the largest, while those from the Littlefield rangeland were the smallest. Seeds collected from the urban site and agricultural farm have higher germination rates than those sampled from the rangelands. Compared to domesticated crops, silverleaf nightshade seeds require longer imbibition time. Seed germination was better in potting mix than in sand or combined potting mix and sand and was significantly reduced by salt and abscisic acid treatments. Overall, results of the study highlight the crucial role of local environments in conditioning the transgenerational adaptation of species, particularly with respect to germination. Recommendations for silverleaf nightshade control are presented based on the observed variations in the germination behavior of populations within specific ranges.