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The clover stem borer (CSB; Languria mozardi) is a native North American beetle whose larvae develop inside the stems of a broad range of herbaceous host plants, including sundial lupines (Lupinus perennis). Sundial lupine is an imperiled species in many of the jurisdictions where it occurs, and three rare butterfly species depend on it as a larval host plant. As such, sundial lupines are the focus of many conservation projects. Larval damage to the inside of lupine stems reduces pod production, and is thus a threat to the long-term health of lupine populations. Infestations tend to go unnoticed, partly because so much of the insect's life cycle is spent inside the plant stem. Our description of field indicators is intended to help professionals working on lupine conservation projects recognize CSB activity. In Maryland, sites infested with CSB are connected to the anthropogenic meadow network, whereas sites that are not infested are separated from it by a forest buffer.
Mat-forming vines constitute half of invasive plant cover in eastern United States forests. Although glyphosate provides effective control, it has been garnering waning public acceptance due to its potential for harming human health and nontarget organisms, and due to the evolution of plant resistance. Since 67% of eastern Unites States forests are owned by private individuals, finding more acceptable chemical controls for invasive plants is important. Organic herbicides have been used for herbaceous weed control in agriculture. However, there have been no published studies of their efficacy in controlling woody plants or of their potential nontarget effects in natural areas. We compared the ability of two commercially available, organic herbicide formulations (pelargonic acid and cinnamon plus clove oils) against glyphosate to suppress growth of four woody vines, Akebia quinata, Euonymus fortunei, Hedera helix, and Vinca minor, in an urban woodland. We also tested whether these herbicides affected soil nematodes and the germination of moss and fern spores from soil. We found that glyphosate killed these vines after two spray treatments, but that a third treatment was needed the next year for the organic herbicides to kill or reduce vines. This reduction lasted into a third summer. We detected no herbicide effects on nematode densities and functional feeding groups, nor on abundance and species richness of moss and fern germinants. Although these organic herbicides cost 5–6.5 times more than glyphosate at dosages used, they greatly reduced these woody vines and can expand choices for chemical plant control for natural areas managers.
Plants blooming simultaneously may interfere with each other's pollination (competition for pollinators) or enhance each other's pollination (pollinator sharing). In this study we asked the question: What is the effect of native palm flowering on the pollination of a native wildflower species? Using potted plants of pineland golden trumpet Angadenia berteroi (Apocynaceae), we placed plants with flowers about to open in the field in two positions: within 5 m of flowering palms (Sabal palmetto and Serenoa repens, Arecaceae), and within 5 m of palms that were not flowering. We observed visitors to the flowers of A. berteroi on plants in both situations. We collected the corollas of the one-day flowers to look for pollen deposition on the receptive stigmatic surface. The same flowers were monitored to see if they set fruit. Flowers on plants in both situations were visited, but the ones near flowering palms less frequently. More of the flowers from plants near non-flowering palms had pollen deposited on the stigma, but fruit from flowers presented did not differ between treatments. This experiment demonstrates that flowering palms, with their large floral displays full of pollen and nectar, diminished pollinator visits to one of the most beautiful of the pine rockland wildflowers, resulting in less pollination in A. berteroi. As fire suppression can lead to an understory with overrepresentation of understory palms in pine rocklands, practitioners should manage natural areas to prevent these super-attractive species from hogging floral visitors to the detriment of less numerous native wildflowers.
The use of goat browsing for invasive plant management is growing in the United States, but many questions remain about the efficacy of goat browsing for invasive plant control. One common concern of land managers and other stakeholders is whether goats can spread invasive plants through endozoochory (seed dispersal via ingestion and excretion in feces). We evaluated this possibility using common buckthorn (Rhamnus cathartica), an invasive shrub for which goats are often employed as a control method. Goats were fed buckthorn berries, and their feces were collected and examined at 24 hr, 48 hr, and 72 hr post-ingestion for intact seeds that survived gut passage. A low proportion of buckthorn seeds (2%) made it through the goat digestive system intact. Of these, only 11% remained viable, compared to 63% viability of control seeds. We conclude that consumption of buckthorn fruits by goats effectively destroys seeds, indicating low risk of dispersal via gut passage. To put these results in context, and provide more guidance for land managers, we additionally reviewed literature investigating seed recovery following ingestion by goats. Based on a synthetic analysis across 28 plant species, we found that seeds >4 mm long were unlikely to be recovered from feces intact, while smaller seeds posed higher dispersal risk.
Conservation of obligate-seeding shrubs from Mediterranean-climate regions is an international conservation priority. Morro manzanita (Arctostaphylos morroensis) is one such shrub whose persistence may depend on germination and establishment from soil-stored seeds following fire. However, fire has been virtually eliminated from its remaining habitat. Thus, conservation of A. morroensis may depend on actions that stimulate germination to establish new populations. We characterized seed banks in different-aged stands and examined viability and germination of A. morroensis seeds in response to various cues, including heat and charred wood. We found that seed density varied greatly among sites, although not increasing with stand age as predicted. Rather, the oldest stand had especially low seed densities and viability. Viability of A. morroensis seeds was low—on average ∼4%—limiting germination. Surprisingly, ∼40% of viable seeds germinated with no fire treatments. Neither heat nor charred wood alone enhanced germination; however, when combined the two resulted in highest germination. Seeds soaked in water prior to heat-and-charred-wood treatments had significantly reduced germination, suggesting that prescribed burns conducted in the wet season would result in a poor germination response. Characterization of the seed bank and determination of the cues stimulating germination can provide information vital to the maintenance of this and similar obligate-seeding species.
Globally, urbanization and other forms of land use change have been implicated in widespread pollinator declines and disruptions to plant–pollinator interactions. A growing body of literature, however, suggests that urban habitat fragments can provide oases for both plant and insect diversity. A micro-ecosystem on our college campus was created to represent the longleaf pine savannas (sandhills) that once dominated upland ridges throughout the Southeast. To assess the ability of this site to support wild insect pollinators, from May through August for three years (2016–2018) we compared visitation to two abundant flowering plant species, Bidens alba (a generalist-pollinated composite) and Chamaecrista fasciculata (a specialist-pollinated legume), between the campus micro-ecosystem and a nearby site within a large conservation area containing sandhill habitat undergoing restoration. We found that, for both plant species, total insect visitation rates did not differ between years or sites, suggesting that the small urban fragment is capable of maintaining abundant pollinators. The identity of generalist visitors to Bidens alba, however, differed dramatically between sites. Wild hymenopterans constituted more than two-thirds of all insect visits in the campus site but less than half in the conservation area, where butterflies, flies, and beetles were also common visitors. The high density of flowers in the campus site is likely at least partially responsible for the high abundance of hymenopterans, a result consistent with that of many other studies showing that hymenopterans are less sensitive to urbanization than are other insect groups.
The impact of land-based recreational activities on water quality in rivers and streams is an important topic for land stewardship. It is not a topic that has been yet systematically studied. This paper surveys the scientific literature on the topic and offers preliminary conclusions for ecologists, trail and park managers, and outdoor enthusiasts. The review examines three categories of recreational activity—hiking and jogging; horseback riding, dog-walking, picnicking and camping; and biking and off-road vehicle riding—in terms of three broad dynamics of ecological impact that directly affect water quality: (1) soil compaction and associated soil loss into waterways; (2) reduction of ground cover and runoff of organic litter with associated soil loss into waterways; and (3) fecal contamination and its impact on waterways. Preliminary conclusions suggest that the greatest impacts on water are a function of trail placement and design (siting, grading, contouring, surface composition, and immediate surroundings). Type of trail use is also highly salient, especially in the case of off-road vehicles when specified restrictions on trail use are absent or when certain behavioral attributes are present. There are important commonalities of water impact stemming from all types of recreation reviewed and relative impacts sometimes defy simple comparison (e.g., motorbikes appear to have greater impact uphill than hiking and horseback riding but less impact downhill). Frequency of trail use is also examined in connection with water quality as are the significant effects of fecal contamination associated with overnight camping, horseback riding, and dog-walking.
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