Native Plant Restoration Research Articles

The Effects of Short-term Drying on Seed Germination in Rosa

Seed propagation of roses is used for breeding new cultivars, native plant restoration, selected rootstocks, and some roses used for hip production (Gill and Pogge, 1974; Krussmann, 1981; Weremark et al., 1995). Rose achenes (seeds) are notorious for having low viability and erratic germination (Buckley, 1985). Factors such as genetics, temperature during both seed maturation and stratifi cation, scarifi cation, pericarp removal, and plant growth regulators can affect germination frequency and uniformity (Buckley, 1985; Gudin et al., 1990; VonAbrams and Hand, 1956). Satisfactory viability has been retained for multiple years using dry longterm seed storage of Rosa multifl ora Thunb. and other Rosaceous species (Crocker, 1926; Crocker and Barton, 1931). Short-term drying ( 500 seeds of each cultivar or species were allowed to air dry for four days, and at the same time >500 seeds of each cultivar or species were kept continually moist wrapped in damp paper towels within sealed polyethylene bags. After treatment, all seeds were submerged in distilled water for 24 h. Five replications of 100 seeds were counted for each moisture treatment per cultivar or species per year. Each replication of seeds was mixed with 80 cm of moistened Canadian sphagnum peatmoss (Hyponex Corporation, Marysville, Ohio) and sealed in a 16.8 × 14.9-cm polyethylene bag (Glad zipper bags, Oakland, Calif.). Seeds were cold stratifi ed for 12 weeks at 4 °C and then moved to 14 °C for the duration over which germination was observed (11 weeks in year 1; 16 weeks in year 2). Bags were monitored once per week at which time germinating seeds (seeds with an emerged radicle) were removed and counted. The 2 weeks (X and X +1 ) bracketing the 50% total germination value and their cumulative germination values (C 1 and C 2 , respectively) were used to calculate T 50 for each replication with the following formula. Student’s t tests were calculated using SPSS software (SPSS 11.0 for Windows, Chicago, Ill.): T 50 = X + [(50% total germination – C 1 )/(C 2 – C 1 )]. Short-term drying reduced total percent germination and altered T 50 for R. rubiginosa and R. rugosa, but did not signifi cantly affect germination of the other cultivars or species relative to constant moisture (Table 1, Fig. 1). A signifi cantly longer T 50 in response to shortterm drying was found for R. rubiginosa and shorter T 50 for R. rugosa relative to constant moisture (Table 1). Some may consider the year 1 reduction in total percent germination (6.2% reduction) for ‘Bucbi’ due to short-term drying to be slightly signifi cant (P = 0.10) depending on where one sets their signifi cance threshold, however, in year 2 a trend towards divergence between moisture treatments for ‘Bucbi’ (0.2% reduction; P = 0.96) was not observed (Table 1, Fig. 1). The total percent germination was greater in year 2 at week 11 for both ‘Bucbi’ moisture treatments and the continuous moisture treatment for R. rubiginosa (Fig. 1). Different degrees of physiological dormancy across seed lots collected from the same parents in different years is common for many plant species and can be due to differing environmental conditions (Baskin and Baskin, 1998). Depending on cultivar or species, germination improved or stayed the same when rose seeds were kept moist from harvest through germination relative to short-term drying after harvest. Roses and other Rosaceous species are not generally thought of as having recalcitrant seeds, since viability is generally satisfactory after drying (Crocker and Barton, 1931). In breeding programs where there is a high investment in hand-pollinated seed, not allowing seeds to dry out before stratifi cation treatments could maximize both rapid and a high fi nal percent of germination. Since commercial rose breeding programs generally try to obtain rapid germination after achene harvest and then raise seedlings in greenhouses (Krussmann, 1981), keeping seeds continually moist should not interfere with established protocols and could easily be adopted. On the other hand, if seed is abundant, limited resources may be best allocated using dry storage to delay stratifi cation treatments and germination, a situation which may occur when raising open-pollinated

Factors contributing to the removal of a marine grass invader (Spartina anglica) and subsequent potential for habitat restoration

Our goal is to understand how removal regime and habitat type interact to influence removal success of a marine plant invader and the subsequent potential for restoration. In particular, we investigate the management program designed to eradicate the English cordgrass,Spartina anglica C. E. Hubbard, in marine intertidal habitats of Puget Sound, Washington, United States. Observational and manipulative experiments were used to measure the regrowth (vegetative growth), reinvasion (seedling recruitment), and restoration potential (return to native condition) of invaded habitats. Removal regime (consistent: yearly removal; interrupted: yearly removal with the last year missed) and habitat type (low salinity marsh, mudflat, cobble beach, and high salinity marsh sites) were considered. The response to removal regime was dramatic. Under consistent removal, cordgrass slowly declined but under interrupted removal, there was substantial regrowth of the invader. This pattern results from the resiliency of belowground biomass and the subsequent high aboveground productivity and seedling growth ofS. anglica. We also found that removal success depended on differences among sites that represent different habitat types. Cordgrass regrowth and reinvasion were substantially higher in the low salinity marsh sites where soils have lower salinity. We also found that at the low salinity marsh sites, some restoration of native plants and soil conditions was evident. At mudflat, cobble beach, and high salinity marsh sites, colonization of native vascular plants and algae not normally present, in the absence of the invasion, occurred. Whether these habitats will eventually revert back to the pre-invasion conditions over a longer period of time is unknown.

Native Plant Restoration on Hawai'i

Restoration projects and nurseries from 7 Hawaiian islands are working jointly to propagate and reestablish rare and endangered plant species and to rehabilitate island habitats. Long-range goals of these projects may benefit rare and endangered fauna. Conservation of habitat and augmentation of rare plant populations are crucial for preserving genetic diversity and recovery. Such efforts have resulted in successful propagation of many at-risk species. The propagation and outplanting efforts of these unique species are described.

Fencing is Key to Native Plant Restoration in Hawai'i

Abstract Fencing creates safety barriers for restoration projects in Hawai‘i. Without fencing and intensive management of feral mammals and nonnative plants, restoration efforts would not be possible. Hawai‘i’s long evolutionary isolation created unique species having few defense mechanisms. Today, its modern position as the commercial hub of the Pacific makes native species especially susceptible to destruction by alien species. Many nonnative plant species occupy modified forests after feral mammals have eliminated native species. Establishment of nonnative plants is rapid in exposed mineral soils and feral mammals and birds aid their dispersal. The construction of ungulate-proof fences and the elimination of feral mammals create recovery areas for both native habitats and rare and endangered species.

Native Plant Restoration of Copper Mine Tailings: II. Field Survival, Growth, and Nutrient Uptake

AbstractCopper mine tailings are difficult to revegetate due to nutrient deficiencies, high acidity, and metal toxicities. Despite these poor substrate properties, native species may be preferred for restoration for ecological and economic reasons, as they may require less long‐term maintenance. In this study, amended and unamended mine tailings are contrasted with a natural soil and gravel for factors potentially limiting to growth. Twelve individuals of five native species (big‐leaf maple, western yarrow, Sitka alder, pearly everlasting, and fireweed) were grown in five different field plots. Plots consisted of: (i) copper mine tailings, (ii) natural soil, (iii) 15 cm of gravel over tailings, (iv) biosolids plus wood chips with 15 cm gravel over tailings, and (v) gravel. Survival was highly variable by species and plot type, with highest survival among all species with pearly everlasting, and highest survival by treatment with the natural soil and biosolids plus wood chips with gravel over tailings. Treatments resulted in a significant difference (p = 0.05) in species biomass production, with the biosolids resulting in highest biomass in all species except big‐leaf maple. Plant nutrient content was also higher with the biosolids. The tailings were extremely acidic and had high exchangeable AI. Sitka alder was most tolerant of the tailings, despite high AI uptake, and was productive across all plot types, possibly due to its tolerance of metals and high nutrient use efficiency. Both Sitka alder and pearly everlasting show promise for revegetating copper mine tailings, although with a biosolids and gravel amendment other native species may do equally well.

Native Plant Restoration of Copper Mine Tailings: I. Substrate Effect on Growth and Nutritional Status in a Greenhouse Study

AbstractCopper mine tailings are difficult to revegetate using native plants unless amendments are added to reduce acidity, decrease metal solubility, and improve nutrient availability. In this study, the effects of two amendments were tested for their ability to improve growth and survival of two native plant species growing in copper mine tailings. Unamended tailings from an abandoned copper mine in Washington State were compared with native soil, sandy gravel from local glacial outwash, tailings with a 15‐cm sandy gravel cap, and biosolids with sandy gravel over tailings. Two native plants, Sitka alder [Alnus viridis subsp. sinuata (Regel) A. Love & D. Love] and pearly everlasting [Anaphalis margaritacea (L.) Benth. & Hook. f.], were grown in a greenhouse for 3 to 4 mo in pots of each substrate. Plant biomass was determined and elemental composition of plant tissues were compared among substrates. Survival of both species was 100% in all treatments, but biomass production varied greatly among treatments, with the highest growth in the biosolids and gravel amendment and lowest growth in unamended tailings. Nutrient content varied by species and substrate with high AI concentrations in Sitka alder. Results suggest that N availability is most limiting to pearly everlasting and P is most limiting to Sitka alder. Use of biosolids in conjunction with gravel appears to be an effective tailings amendment.

Restoration Ecology: Combining the Teaching of Ecological Principles with Group Experiments and Native Plant Restoration on the SDSU Campus

Restoration Ecology: Combining the Teaching of Ecological Principles with Group Experiments and Native Plant Restoration on the SDSU Campus

WILDFLOWER SPECIES ADAPTABILITY IN GEORGIA AND SOUTHEASTERN UNITED STATES

Eighty horticultural wildflower taxa were evaluated for performance at three locations over three years in Georgia (USDA climatic zones 7-9). Plant performance and persistence were rated as superior perennial/reseeding annual, secondary perennial, annual, and unadapted. Length of bloom season for each species was determined at each location. Forty-eight species were rated as superior, 11 as secondary, 14 annual, and seven were not adapted. From these data, specialty mixes for meadow gardens, roadside beautification, landscape color, and native plant restoration areas have been formulated for use in cost-efficient landscape plantings. The mixes contain 10-15 species with overlapping bloom seasons to provide color during most of the growing season of eight months.