Opuntia Fragilis Research Articles

INFLUENCE OF CLIMATE CHANGE ON THE SPREAD OF INVASIVE ALIEN PLANT SPECIES IN THE TERRITORY OF THE LOZENSKA MOUNTAIN

The paper presents a comparative analysis of the data on the main climatic components for three periods - 1921-1945; 1965-1975; 2000-2015 and their connection with the distribution of Invasive alien plant species (IAS) on the territory of Lozenska Mountain. Among the most important features of the mountain’s climate that favorably affect the spread of IAS are the two precipitation maximums and minimums and the period of drought. In response to climate and other environmental changes, IAS on the territory of the mountain are spread in two ways - by forming monodominant communities in extreme habitats or by integrating their populations into the local communities and gradually increasing their presence in them, accompanied by changing ecological conditions of the habitat. Four potential invasive alien plant species (PIAS) have been identified: Opuntia fragilis (Nutt.) Haw., Opuntia engelmannii Salm-Dyck ex Engelmann, Lupinus polyphylus Lindl., Impatiens baulfourii Hook.f., to which population monitoring and control measures need to be implemented.

Northern Range Limit of Opuntia fragilis and the Cactaceae is 56°N, Not 58°N

Two of the most used sources for distributions of cacti (Cactaceae) indicate the family's northern range limit is either 58°N or 58°15′N for Opuntia fragilis. However these sources overstate the range limit by almost two degrees, an error that probably originated as a simple misreading of the latitude of Fort St. John. I discuss records of O. fragilis at and just south of 56°17′ N along the Peace River valley between Fort St. John, British Columbia and Peace River, Alberta, as well as why it is surprising but unlikely that specimens currently exist farther north. An error in latitude of 2° (223 km) in range can adversely affect ability to empirically estimate effects of climate change.

Opuntia fragilis (Nuttall) Haworth in Illinois: Pad Dynamics and Sexual Reproduction

Abstract We studied the sole population of Opuntia fragilis in Illinois for four years, tracking plant and individual pad fates, and investigating flowering success. The population appears to be fairly stable in size from year to year. The fate of a given pad is strongly dependent upon the position of the pad within the plant; basal pads and transitional pads are likely to remain from year to year, while terminal pads experience substantially higher rates of death or fragmentation, and are much more likely to produce new growth and thus become transitional pads themselves. A fungal “black spot” disease, probably a result of winter damage, appears to negatively affect pad survival during some winters but not during other winters. While genetic diversity is not low, flowers do not produce viable seed, even when controlled cross-pollinations are performed, although they are visited by a variety of potential insect pollinators.

Extensive Green Roof Species Evaluations Using Digital Image Analysis

This research examined plant area covered (plant cover) for six plant species on an existing modular extensive green roof in a semiarid climate. Species evaluated were Antennaria parvifolia Nutt., Bouteloua gracilis (Kunth) Lag., Delosperma cooperi (Hook. f.) L. Bol., Eriogonum umbellatum Torr. aureum ‘Psdowns’, Opuntia fragilis Nutt., and Sedum lanceolatum Torr. Many methods for measuring plant cover are subjective and based on semiquantitative measurements. This study compared digital image analysis data (DIA) with manually collected converted two-dimensional data (C2D) for plants grown on an extensive green roof. For each plant in the study, digital images and manual two-dimensional measurements were taken on four dates (at 6-week intervals) in 2008 and on four dates (at 6-week intervals) in 2009. Additionally, comparisons between DIA data and final biomass, and C2D and final biomass, were performed. Plant cover increased for all six species during the 2008 growing season. However, E. umbellatum aureum ‘Psdowns’ had a low overwintering rate (12.5%) and was removed from analysis in 2009. In the spring of 2009, four of the five remaining species exhibited decreased plant cover as a result of winter dieback; the one exception was O. fragilis. In terms of plant cover, both quantification methods (C2D and DIA) revealed that B. gracilis and D. cooperi had more plant cover than A. parvifolia, O. fragilis, and S. lanceolatum by the end of the study. Thus, five of the six species evaluated in this study are appropriate for use in extensive green roof applications in semiarid regions. High levels of correlation were found between the DIA and C2D data sets (r = 0.77) averaged over the five species on all eight data collection dates. The groundcover species (A. parvifolia, D. cooperi, and S. lanceolatum) had a higher correlation on average (r = 0.83) than the upright (B. gracilis, r = 0.70) and decumbent (O. fragilis, r = 0.65) species. Additionally, DIA and final biomass correlations showed parallel trends with groundcovers averaging r = 0.83, upright r = 0.64, and decumbent r = 0.41. Therefore, using DIA to evaluate plant cover and biomass accumulation is especially appropriate for groundcover species.

Opuntia fragilis: Taxonomy, Distribution, and Ecology

Abstract Opuntia fragilis is the smallest and most cold-hardy species of North American prickly pear, with an unusual distribution. This document is a review of its taxonomy, distribution, and ecology.

Lichens Promote Flowering of Opuntia fragilis in West-Central Wisconsin

Clumps of the cactus Opuntia fragilis growing in association with mats of the lichens Cladina mitis, Cladina rangiferina and a spikemoss, Selaginella rupestris, were discovered in an agricultural field in Pepin County, Wisconsin, that had been abandoned for over 50 y. The association appeared to be beneficial to the cactus, which flowered almost exclusively in the presence of lichens. Of 294 cactus clumps examined in 2001, 127 grew in the presence of lichen mats and, of these, 24 flowered, producing 91 flowers, while none of the cacti growing in the absence of lichens flowered. In 2002, 19 out of 265 cactus clumps flowered, all but one in the presence of lichens. All sizes of cacti in the presence of lichens flowered and the probability of flowering increased with cactus size. In addition, the cacti that flowered had cladodes that were on average 19% heavier than those of cacti that did not flower. The presence of lichens lowered summer soil temperatures 2–4 C compared to soil temperatures in the absence of lichens. Cooler soil temperatures conserve soil moisture better, which may enhance flowering in these cacti.

Preble's Shrew and Great Basin Pocket Mouse from the Centennial Valley Sandhills of Montana

tana sandhills habitat is poorly documented. During a 1999 faunal survey of the Centennial Valley Sandhills in Beaverhead County, extreme southwestern Montana, we captured specimens of Preble's shrew (Sorex preblei) and Great Basin pocket mouse (Perognathus parvus). Both are state Species of Concern (Montana Fish, Wildlife & Parks; Montana Natural Heritage Program) and are rarely collected in Montana. The Centennial Valley Sandhills are approximately 2 to 3 km wide and 14 km long (between 44'40'N, 111'42'W and 44'42'N, 111'49'W) at an average elevation of 2030 m; they are north of Lower and Upper Red Rock lakes near the east end of the Centennial Valley (Sonderegger and others 1982). The sandhills are small and generally stable dunes. Sandhills vegetation (Lesica and Cooper 1999) is a mixture of treeless successional types dominated by shrubs (Artemisia tridentata, A. tripartita, Chrysothamnus nauseosus, C. viscidiflorus, Tetradymia canescens), forbs (Lupinus argenteus, L. sericeus, Machaeranthera canescens, Opuntia fragilis, Phaecelia hastata, Psoralea tenuiflora) and grasses (Agropyron dasystachyum, Festuca idahoensis, Koeleria cristata, Poa nevadensis, Stipa comata). Standing water is absent within the sandhills proper, once winter snows melt in May, but is present south of the sandhills in nearby wetlands surrounding Upper and Lower Red Rock lakes. Shrews and pocket mice were collected from a series of 6 pitfall trap lines (10 stations, 30 m between stations, with a single can trap at each station; 60 cans total) and 3 drift-fence arrays (each with 4 pitfall can traps; 12 cans total). Pitfall lines were set 25 to 26 May 1999, and driftfence arrays were established on 25 May; each line and array was run continuously (except to clean and repair traps) until retrieved on 21 to 22 September (7000 trap-nights total on the pitfall lines and 1380 trap-nights total for the drift fence arrays). All pitfall can traps were in place for 115 to 117 nights of trapping. Traps were examined daily while we were at the sandhills (25 to 28 May, 28 June to 2 July, 28 to 30 July, 21 to 22 September), although no shrews or pocket mice were captured while we were present.

Ecological history and population dynamics of a disjunct population of Brittle Prickly-pear Cactus, Opuntia fragilis (Cactaceae), in eastern Ontario

Ecological history and population dynamics of a disjunct population of Brittle Prickly-pear Cactus, Opuntia fragilis (Cactaceae), in eastern Ontario

Freezing and heat tolerance ofOpuntiacacti native to the Canadian prairie provinces

Seasonal changes in the freezing tolerance in situ were determined for Opuntia fragilis and Opuntia polyacantha native to southern Saskatchewan, Canada. Wintering terminal cladodes of O. fragilis and O. polyacantha survived −50 and −40 °C, respectively, without any apparent tissue injury. Approximately 50% of the cladodes of O. fragilis collected on either 10 October or 10 December 1985 tolerated −70 °C and immersion in liquid nitrogen (−196 °C) following slow prefreezing to −40 °C. These are the lowest values reported for the freezing tolerance of cacti as determined by regrowth and tissue necrosis. Newly formed cladodes of the same species did not tolerate −3.5 °C in June, but freezing tolerance increased from −7 to −50 °C from 6 September to 10 October. This increase in freezing tolerance was accompanied by a decrease in water content from 5.4 to 2.6 g H2O/g dry wt. and the cladodes were shrunken and reduced by approximately 30% in diameter. Although Opuntia is a succulent plant that avoids drought by storing water in the cladodes, during cold acclimation O. fragilis appears to shift to a more drought-tolerating strategy. In midsummer, the current year cladodes of O. fragilis tolerated a 60-min exposure to 50 °C, while the previous year cladodes tolerated 55 °C without any visible symptoms of injury. Temperature extremes of −30 and 51 °C were recorded at the microhabitats of O. fragilis. This study demonstrates that this species can acclimate to tolerate both the high and low temperature extremes experienced in its native habitat. Keywords: cacti, cold acclimation, freezing tolerance, heat tolerance, Opuntia, water relations.

Interaction of diffuse competition and insect herbivory in limiting brittle prickly pear cactus, Opuntia fragilis (Cactaceae)

We tested the effects of above‐ and belowground competition and evaluated insect herbivory on the growth of a common cactus (Opuntia fragilis) in Sandhills prairie. Our purpose was to determine the independent and joint contribution of these factors to the variation observed in cactus size and local abundance. We manipulated ambient prairie vegetation and surface water availability in a full factorial design. When Opuntia fragilis was released from competition with surrounding vegetation, it grew significantly larger in the second growing season, both in terms of number and size of new cladodes. Ramets grown within live prairie vegetation averaged no net growth. These ramets were also more frequently fed upon by the larvae of two internally feeding cactus insects. As a result, insect herbivory reinforced the competitive suppression of the cactus by grasses. Water supplementation had no significant effect, either on cactus growth or on insect herbivory. We conclude that the mechanism by which dense prairie vegetation influenced net growth of O. fragilis was both direct, through competition for nonwater resources such as light, and indirect, through its mediation of feeding by specialized insect herbivores. Furthermore, since the direct growth response to treatment did not precede the indirect effect of habitat‐mediated variation in feeding by insects, our results contradict the current expectation that indirect effects require more time to be expressed than do direct effects.

Indirect versus direct effects of grasses on growth of a cactus (Opuntia fragilis): insect herbivory versus competition.

Variation in plant performance between microhabitats is usually attributed to direct mechanisms, such as plant physiological tolerances or competitive interactions. However, indirect mechanisms, such as differences in herbivore pressure mediated by microhabitat differences, could create the same pattern of variation. In this study, we investigated the effect of insect herbivore pressure on the growth of the grassland cactus Opuntia fragilis under different regimes of grassland canopy cover. Our purpose was to establish the extent to which canopy cover plays a direct, competitive role versus an indirect, mediatory role in cactus growth. We manipulated aboveground microhabitat, specifically the cover of adjacent grasses. The three treatments were: (1) open canopy, with grass pinned down away from the cactus; (2) shaded canopy, with a partial mesh cage staked over the cactus; and (3) ambient grass canopy. We measured seasonal plant growth and recorded changes in insect herbivore occurrence and damage in relation to cover. Cactus growth, defined as the change in number of live cladodes, was higher in the open than under either treatment where the plant was more shaded (P<0.05). However, allocation to new growth, measured as the proportion of new segments (cladodes) in a patch, did not differ among cover treatments. Thus, the hypothesis that physiological constraints, or competition for light, limited cactus performance in grass is rejected. Instead, we found that both cladode mortality, caused by the larvae of a cactus moth borer (Melitara dentata), and occurrence of the moth were lower in the open microhabitat than in either shaded microhabitat. Thus, higher net growth in the open, unshaded treatment, rather than representing a release from competition for light with grasses, was better explained as an indirect effect of grass cover on the activity and impact of the cactus moth. These results show that indirect effects can lead to a misinterpretation of experimental data on direct effects. These data also contribute to an improved understanding of mixed results in the biological control of weedy cacti. Clearly, future evaluations of the relative importance of physiology, competition, and insect herbivory in plant performance must be environmentally explicit.

Exogenous Abscisic Acid Mimics Cold Acclimation for Cacti Differing in Freezing Tolerance.

The responses to low temperature were determined for two species of cacti sensitive to freezing, Ferocactus viridescens and Opuntia ficus-indica, and a cold hardy species, Opuntia fragilis. Fourteen days after shifting the plants from day/night air temperatures of 30/20[deg]C to 10/0[deg]C, the chlorenchyma water content decreased only for O. fragilis. This temperature shift caused the freezing tolerance (measured by vital stain uptake) of chlorenchyma cells to be enhanced only by about 2.0[deg]C for F. viridescens and O. ficus-indica but by 14.6[deg]C for O. fragilis. Also, maintenance of high water content by injection of water into plants at 10/0[deg]C reversed the acclimation. The endogenous abscisic acid (ABA) concentration was below 0.4 pmol g-1 fresh weight at 30/20[deg]C, but after 14 d at 10/0[deg]C it increased to 84 pmol g-1 fresh weight for O. ficus-indica and to 49 pmol g-1 fresh weight for O. fragilis. Four days after plants were sprayed with 7.5 x 10-5 M ABA at 30/20[deg]C, freezing tolerance was enhanced by 0.5[deg]C for F. viridescens, 4.1[deg]C for O. ficus-indica, and 23.4[deg]C for O. fragilis. Moreover, the time course for the change in freezing tolerance over 14 d was similar for plants shifted to low temperatures as for plants treated with exogenous ABA at moderate temperatures. Decreases in plant water content and increases in ABA concentration may be important for low-temperature acclimation by cacti, especially O. fragilis, which is widely distributed in Canada and the United States.

Freezing Tolerance and Water Relations of Opuntia Fragilis from Canada and the United States

To investigate the influence of winter climate on freezing tolerance at the population level, minimum January air temperatures in the field and cold acclimation determined in the laboratory were compared for Opuntia fragilis. Populations occurred at 20 locations as far north as 56°46' N latitude and at elevations up to 3029 m in Canada and the United States, most of which experience extreme freezing temperatures each winter. Low—temperature responses and water relations of stems were examined in the laboratory at day/night air temperatures of 25°/15°C and 14 d after the plants were shifted to a 5°/—5°C temperature cycle. Cold acclimation averaged 17°C and freezing tolerance averaged —29°C for the 20 populations following a shift to low day/night air temperatures, indicating that O. fragilis has the greatest cold acclimation ability and the greatest freezing tolerance reported for any cactus. Moreover, freezing tolerance and cold acclimation were both positively correlated (r2 ° 0.7) with the minimum temperatures at the 20 locations. Plants lost water during low—temperature acclimation, leading to 30% decreases in cladode and chlorenchyma thickness; the decrease in water content was greater for the five warmest populations than for the five coldest ones. Over the same period, the average osmotic pressure of the chlorenchyma increased from 1.42 to 1.64 MPa, and the relative water content (RWC) decreased from 0.58 to 0.49, but the average osmotic pressure of saturated chlorenchyma was unchanged, indicating no net change in solute content during acclimation. Although the role of water relations in freezing tolerance is unclear, the substantial freezing tolerance and cold acclimation ability of O. fragilis leads to its distribution into regions of Canada and the United States that experience minimum temperatures below —40°C during the winter.

Vegetation sequence on three boreal Manitoban rock outcrops and seral position of Opuntia fragilis

The vegetation sequence on granitic outcrops containing Opuntia fragilis (Nutt.) Haw. was examined at three sites in southeastern Manitoba. The experimentally determined species sequence supported those in the literature: (0) bare rock – pioneer lichens, (1) primary moss mat, (2) secondary moss and lichen mat, (3) tertiary moss and lichen mat, (4) stress-tolerant ruderals, (5) stress-tolerant perennials, (6) perennial grasses, and (7) chamaephytes and phanerophytes. The primary factor determining the sequence was substrate depth, presumably because of its effect on moisture retention. The species composition of the earliest seral stages (0–3) was consistent at all three sites, presumably as a result of propagule availability and the extremely xeric nature of the sere. Variations in the species of subsequent stages may be attributed to the more restrictive dispersal mechanisms of mesic species. Local variations in vegetation scale and pattern were caused by slope, disturbance, crevices or depressions, and encroachment of forest at the forest–outcrop ecotone. Opuntia fragilis, a stress-tolerant perennial, was the first vascular plant in the sequence and colonized mats in stage 2 (occasionally 3). It did not persist in stage 5.

The Brittle Prickly-pear Cactus, Opuntia fragilis, in the boreal forest of southeastern Manitoba

The Brittle Prickly-pear Cactus, Opuntia fragilis, in the boreal forest of southeastern Manitoba

Factors determining the distribution of Opuntia fragilis in the boreal forest of southeastern Manitoba

Opuntia fragilis (Nutt.) Haw. is restricted to south-facing rock outcrops on the shores of certain rivers and lakes in the boreal forest of southeastern Manitoba. Limitations in propagule dispersal, establishment, and maintenance were studied at Bird River (50°25′ N, 95°41′ W) between October 1979 and October 1982. Propagules studied were stem units (pads) because this cactus propagates entirely by vegetative means in this region. Mature terminal pads broke off most easily in the late spring while turgid and rolled downhill (geochory), thus establishing new plants locally. Some pads fell into the river and could float long distances (hydrochory) before being washed ashore. Perhaps less frequently, pads were dispersed over long distances on animals (epizoochory). Marked pads placed in potential habitats showed significantly greater establishment (α = 0.05) on south-facing outcrops than on north-facing or forest sites. Censuses (1979–1982) of an established colony indicated that pad number was increasing by 51% per year. Approximately 6% of the pads were dispersed from the outcrop. The present distribution of O. fragilis appears to be both habitat and dispersal limited.

Opuntia fragilis (Cactaceae) Verified in Illinois Flora

Opuntia fragilis has been reported only once from Illinois. Recent workers have not been able to find a substantiating specimen and have excluded the species from the flora. The missing specimen has now been found and is referable to this species.

Three Noteworthy Cacti of Southwestern Utah

In the spring of 1939 and 1940 Dr. Fred A. Barkley collected some unusual cacti in southwestern Utah in the vicinity of the Desert Experimental Range west of Milford. These cacti were locally known as Opuntia fragilis. Dr. Barkley called the author's attention to them and at the same time further collections were made by Drs. Selar Hutchings and Gordon Marsh of the U.S. Desert Experimental Range Staff.