Seed sourcing for climate-resilient grasslands: the role of seed source diversity during early restoration establishment

Restoration often advocates for the use of local seed in restoration, however increasingly new strategies have been proposed to incorporate diverse sources to maintain evolutionary potential within seed mixes. Increasing seed sources per species within a seed mix should increase genetic variation, however, few empirical studies have evaluated how seed source diversity impacts plant community composition following restoration. Thus, the goal of this research was to compare the use of single or multi-source seed mix treatments to plant community diversity following restoration. Using 14 species commonly applied in grassland restoration, we examined plant community diversity following restoration comparing seed mixes with either one or five sources per species across two restoration sites in Minnesota and South Dakota, United States. Following seeding, species establishment and abundance were recorded to calculate plant diversity for each seed mix treatment. There were no major effects of seed mix treatment on community emergence and diversity observed, with the majority of plant establishment reflecting non-seeded species. However, site-specific differences were observed. Heterogeneous land-use history associated with the Minnesota site likely contributed to differences across the restoration treatments. In contrast, community diversity at the South Dakota site was homogeneous across seed mix treatments with changes in plant community influenced solely by early season species establishment. This suggests land-use history irrespective of seed mix treatment influences establishment and persistence, particularly in the first year following restoration. Future monitoring across seasons will be needed to evaluate if community diversity changes in response to seed mix treatment.

Lurking in the depth: Pond depth predicts microhabitat selection by Rhinella icterica (Anura: Bufonidae) tadpoles at two different sampling scales

Habitat selection has long been a central theme in ecology and has historically considered both physiological responses and ecological factors affecting species establishment. Investigating habitat selection patterns at different scales can provide important information on the relative roles of the environmental factors influencing the organisms’ abilities to use their surrounding habitat. This work aimed at investigating which environmental factors determine habitat selection by Rhinella icterica tadpoles, and also took the opportunity to investigate how the scale in which tadpoles and environmental data are sampled might influence the habitat selection results. A total of 2.240 tadpoles were counted in the whole sampling area, and while substrate cover and depth were the variables that better explained the abundance of tadpoles at the larger scale (plot level), depth and water turbidity better explained tadpoles’ abundance at the smaller scale (subplot level). The results suggest that avoiding predation by matching the background color is a likely process explaining tadpoles’ occupancy at both scales. Depth is known to influence tadpole habitat use in the tropics, and although its combination with turbidity and substrate cover varied between scales, our study suggests that sampling at different scales might not affect the inferred ecological processes driving habitat selection. This information might also be useful to predict tadpoles’ responses to micro-environmental perturbations and help in guiding the choice of parameters that should be taken into account when analyzing the effects of habitat degradation in Atlantic Forest amphibian populations.

Invasive lizard has fewer parasites than native congener

Invasive species can carry parasites to introduced locations, which may be key to understand the success or failure of species establishment and the invasive potential of introduced species. We compared the prevalence and infection levels of haemogregarine blood parasites between two sympatric congeneric species in Lisbon, Portugal: the invasive Italian wall lizard (Podarcis siculus) and the native green Iberian wall lizard (Podarcis virescens). The two species had significant differences in their infection levels: while P. virescens had high prevalence of infection (69.0%), only one individual of P. siculus was infected (3.7%), and while P. virescens exhibited an average intensity of 1.36%, the infected P. siculus individual had an infection rate of only 0.04%. Genetic analyses of 18S rRNA identified two different haemogregarine haplotypes in P. virescens. Due to the low levels of infection, we were not able to amplify parasite DNA from the infected P. siculus individual, although it was morphologically similar to those found in P. virescens. Since other studies also reported low levels of parasites in P. siculus, we hypothesize that this general lack of parasites could be one of the factors contributing to its competitive advantage over native lizard species and introduction success.

An Assessment of the Physico-Chemical Parameters of Mangrove Soils that Support Nypa fruticans and Other Mangrove Species Establishment in the Cameroon Estuary

Invasion of Nypa palm into mangroves is a problem in the Cameroon Estuary. Soil variability is one of the dominant features that support Nypa palm establishment. The objective was to characterize the soil under the different mangrove stands; Purely Nypa palm stands (A), mixed stands i.e Nypa palm and other mangrove species (B) and other mangrove species i.e Nypa palm free (C), determine the principal soil characteristic critical for Nypa spread. 9 plots of 20 x 20 m were laid in each of the sites. 27 soil samples were collected in the North, West, South East and Center at a depth of 30 cm in these three sites using a soil auger. The results in the three sites indicated that; soils were acidic (3.87- 4.39), pH values did not significantly differ (alpha >0.05), organic matter was low in A (12.32%) and B (16.35%).Soil Organic Carbon ranged from (4.52 to 7.06%). High percentage of organic carbon content was recorded in C (7.06%). Low percentage of organic carbon was found in A (4.52%). Total nitrogen varied from 1.04 g/kg, 1.70g/kg, 1.80 g/kg in sites C, A and B. In all the mangrove stands, the values of Exchangeable Ca content were below 4.0 cmolkg-1. Soil texture in the three sites were; sandy, clay and silt. Power test showed no significant different in soil types between the three sites (p>0.05). According to the component matrix the factor is positively loaded by soil EC, moisture content, organic matter, organic carbon, N, C/N, CEC, Ca, Mg, K, Na, Clay, Silt, and negatively loaded by the percent sand. This study therefore, suggests that since soil plays key role in Nypa palm establishment, there should be constant monitoring of soil quality to forestall drastic changes that will jeopardize the survival of the mangroves. Nypa palm seedlings should also be physically removed from mangrove forest to prevent colonization. In addition, more mangrove seeds should be planted in deforested mangrove areas to close the window of opportunity for the palms.

Increased Arctic climate extremes constrain expected higher plant reproductive success in a warmer climate

The low reproductive success of Arctic plants is predicted to increase as the climate warms. However, climate extremes add complexity to these predictions. In the extremely cold year of 2018, multiple Arctic trophic levels experienced reproductive failure. We analysed a unique long-term record of seed viability from experimentally warmed and ambient plots at Alexandra Fiord, Ellesmere Island which has been running since 1992 and included 2018 and the extremely warm year of 2019. Positive and negative July temperature anomalies and summer temperatures have increased significantly by 0.5, -0.3 and 0.4°C/decade since 1977, resulting in greater extremes and increased inter-annual variation. Seed viability of some species has increased with climate warming. Across years, seed viability of woody species was consistently higher in warmed than ambient plots while the opposite was true for forbs. In 2018, seed viability of woody species in ambient plots was significantly lower than normal but comparable with past years for forb species. Not all species returned to normal seed viability levels in 2019. Our study highlights the potential for greater sexual reproductive failure in tundra plants with increasing climate extremes. We suggest that poor seed viability of woody species in cold years could constrain shrub recruitment and may aid forb species establishment on bare tundra.

A quantitative assessment of site-level factors in influencing Chukar (Alectoris chukar) introduction outcomes

Chukar partridges (Alectoris chukar) are popular game birds that have been introduced throughout the world. Propagules of varying magnitudes have been used to try and establish populations into novel locations, though the relationship between propagule size and species establishment remains speculative. Previous qualitative studies argue that site-level factors are of importance when determining where to release Chukar. We utilized machine learning ensembles to evaluate bioclimatic and topographic data from native and naturalized regions to produce predictive species distribution models (SDMs) and evaluate the relationship between establishment and site-level factors for the conterminous United States. Predictions were then compared to a distribution map based on recorded occurrences to determine model prediction performance. SDM predictions scored an average of 88% accuracy and suitability favored states where Chukars were successfully introduced and are present. Our study shows that the use of quantitative models in evaluating environmental variables and that site-level factors are strong indicators of habitat suitability and species establishment.

Sectoral Impacts of Invasive Species in the United States and Approaches to Management

Invasive species have a major effect on many sectors of the U.S. economy and on the well-being of its citizens. Their presence impacts animal and human health, military readiness, urban vegetation and infrastructure, water, energy and transportations systems, and indigenous peoples in the United States (Table 9.1). They alter bio-physical systems and cultural practices and require significant public and private expenditure for control. This chapter provides examples of the impacts to human systems and explains mechanisms of invasive species’ establishment and spread within sectors of the U.S. economy. The chapter is not intended to be comprehensive but rather to provide insight into the range and severity of impacts. Examples provide context for ongoing Federal programs and initiatives and support State and private efforts to prevent the introduction and spread of invasive species and eradicate and control established invasive species.

Evaluating winter annual grass control and native species establishment following applications of indaziflam on rangeland

Indaziflam, a PRE herbicide option for weed management on rangeland and natural areas, provides long-term control of invasive winter annual grasses (IWAGs). Because indaziflam only provides PRE control of IWAGs, POST herbicides such as glyphosate can be mixed with indaziflam to control germinated IWAG seedlings. Field trials were conducted at three sites on the Colorado Front Range to evaluate glyphosate dose required to provide adequate POST IWAG control and compare long-term downy brome (Bromus tectorum L.), Japanese brome (Bromus arvensis L.), and feral rye (Secale cereale L.) control with indaziflam and imazapic. Two of the three sites were void of desirable species, so species establishment through drill seeding was assessed, while the remnant native plant response was assessed at the third site. Herbicide applications were made March 2014 through April 2015, and two sites were drill seeded with native species 9 mo after herbicide application. Yearly visual control evaluations, biomass of all plant species, and drilled species stand counts were collected. Glyphosate at 474 g ae ha−1 reduced B. tectorum biomass to zero, while glyphosate at 631 g ae ha−1 was needed to reduce biomass to near zero at the S. cereale site. At all three sites, only indaziflam treatments had significant reductions in IWAG biomass compared with the nontreated check at 3 yr after treatment (YAT). By 3 YAT in the drill-seeded sites, cool-season grass frequency ranged from 37% to 69% within indaziflam treatments (73 and 102 g ai ha−1), while imazapic treatments ranged from 0% to 26% cool-season grass frequency. In the site with a remnant native plant community, indaziflam treatments resulted in a 3- to 4-fold increase in native grass biomass. These results indicate that the multiyear IWAG control provided by indaziflam can aid in desirable species reestablishment through drill seeding or response of the remnant plant community.

Fish diversity at the vicinity of hatiya island, Bangladesh

This study was aimed to identify the present status and threats on the fish diversity of Hatiya Island, Noakhali, Bangladesh. Five sampling stations were at Chairman ghat, Katakhali ghat, Tamruddin ghat, Burirdona ghat, Domar Bazar. Data were collected using questionnaire interviews (QI), focus group discussions (FGD), and key informant interviews (KII). A total of 38 fish species were recorded belonging to 9 orders and 21 families. Siluriformes was the most abundant order (38%), whereas Cyprinidae was the richest family (18.42%). Based on IUCN red list of threatened species 2015, 26% species was categorized as Locally Threatened in Bangladesh, following 13% as Vulnerable, 13% as Endangered, 63% as Least concerned, 3% as Data Deficient (DD) and 8% was Not Threatened (NT). Overexploitation, water pollution, habitat degradation and climate change were identified as the major threats for declining of fish diversity in the study area. This study recommends sustainable fisheries management, restocking economically important fish species, establishment of sanctuary, maintenance of fishing gears, control of pollution, and the implementation of the fish act for conservation of fish biodiversity of the Hatiya Island, Noakhali. Bangladesh J. Zool. 48(1): 45-55, 2020