Field emergence of native boreal forest species on reclaimed sites in northeastern Alberta

Abstract

N ATIV EP L A N TS | 1 6 | 3 | F A L L 2 0 1 5 205 A B S T R A C T Direct sowing is an underutilized technique for establishing native species on re-claimed land in the mineable oil sands region of northeastern Alberta. This study evaluated the effect of sowing season (spring versus fall) and propagule type (clean seeds versus whole fruit) on emergence of 41 species. Species were sown on 3 dis-parate sites, each prepared in the standard method for that operation and time and having differing slopes and aspects. Of 41 species, 27 emerged at some level, and of these, 9 species established and were reproducing by seeds, tillers, or rhizomes. These 9 species were smooth blue aster (Symphyotrichum laeve (L.) Á. Löve & D. Löve [Asteraceae]); shrubby cinquefoil (Dasiphora fruticosa (L.) Rydb. [Rosaceae]) and wild strawberry (Fragaria virginiana Duchesne [Rosaceae]), which emerged best from fall-sown seeds; fringed brome (Bromus ciliatus L. [Poaceae]); Canadian needle grass (Hesperostipa curtiseta (Hitchc.) Barkworth [Poaceae]); Canada goldenrod (Sol-idago canadensis L. [Asteraceae]); Raup's Indian paintbrush (Castilleja raupii Pennell [Orobanchaceae]) and prickly rose (Rosa acicularis Lindl. [Rosaceae]), which emerged equally well from seed broadcast during the fall as during the spring; and Mt Albert goldenrod (Solidago simplex Kunth [Asteraceae]), which emerged best from seed broadcast in the spring. Smreciu EA, Gould K. 2015. Field emergence of native boreal forest species on reclaimed sites in northeastern Alberta. Native Plants Journal 16(3):204–226. CONVERSIONS m × 1.1 = yd cm × 0.4 = in m 2 × 10.2 = ft 2 ha × 2.5 = ac kg × 2.2 = lb (°C × 1.8) + 32 = °F Photos courtesy of Wild Rose Consulting Inc This open access article is distributed under the terms of the CC license (http://creativecommons.org/licenses/byncnd/3.0) and is freely available online at: http://npj.uwpress.org O il and gas extraction is a major component of the Canadian economy, and is especially so in the province of Alberta. Some of the largest oil reserves are found in the oil sands of northeastern Alberta, with extrac-tion resulting in disturbance of large tracts of boreal forest. Reclamation of these disturbances is ongoing, progressively re-claiming older areas as new areas are mined. The primary aim of reclamation efforts is to restore functioning communities and ecosystems on the reconstructed landscape that are similar to those that existed prior to disturbance. A wide range of species and deployment methods are necessary to meet the di-verse conditions resulting from changes to hydrology, soils, and elevations and aspects. Although planting nursery-grown seedlings is the most common way currently used to establish native species on reclaimed sites in the oil sands, broadcasting seeds results in greater spatial diversity due to random scatter-ing and uneven emergence over time. Within the Canadian Oil Sands Network for Research and Development Environmental and Reclamation Research Group (CONRAD ERRG), a study of 41 native boreal species was conducted. Many woody species are currently harvested and banked for inclusion in reclamation efforts in northeastern Alberta. Very few non-woody species are used in these operations, however, despite their importance to the vegetation community struc-ture and function. Additionally, many native boreal species, woody and herbaceous, are of particular importance to local First Nations and also play a role in nurturing wildlife. To ad-dress these concerns, this study selected an array of species: early seral species, those found under closed canopy, those with edible parts, those that provide browse for wildlife, and species of interest for other ecological considerations. Seeds of boreal species often require stratification prior to germination (Baskin and Baskin 2001) as a reflection of their adaptation to colder climates. Some may emerge more quickly or more completely from fall sowing. For some biennial species, establishment following early spring seed set is com-mon. There may be a difference in emergence from cleaned seeds and whole fruit for species with fleshy fruit. Some fruits contain inhibitors that prevent germination (Mayer and Poljakoff-Mayber 1982; Hassan and others 2013), and some seeds require scarification as would occur when digested. And for other species, the intact fruit may provide the seeds with an initial source of moisture and nutrients (Smreciu and Barron 1997). Studies have explored direct sown seed for reclamation of prairie (Brown 1974; Pahl and Yeung 1998) and alpine (Haeus-sler and others 1999; Macyk 2001) regions as well as northern latitudes (Helm 2001; Mougeot and Withers 2001). These stud-ies looked primarily at native grasses and legumes. In prairies, the sowing was generally successful; however, in alpine and northern climes, the resulting cover was an impediment to shrub and tree species. Some of this information can be applied to disturbances in the oil sands, but complications unique to the area and to the type of disturbance, as well as the scale of disturbance, warrant a closer examination. The goal of this experiment was to evaluate the effect of sowing season on the emergence and survival of 41 native shrub and forb species. For the 18 species that bear fleshy fruit, a second variable was added. Emergence was compared be-tween plots sown with seeds that had been extracted (cleaned) versus plots sown with intact fruits. Each treatment was tested at the 3 experimental sites described below.