Jeffrey L. Walck

Relative competitive abilities and growth characteristics of a narrowly endemic and a geographically widespread Solidago species (Asteraceae)

Relative competitive ability and growth characteristics of the narrow endemic Solidago shortii were compared to those of the geographically widespread S. altissima. Competition and growth studies were conducted over the entire growing season in an ambient-temperature greenhouse, using a 3:1 (v/v) native limestone soil/river sand mixture. Results from a de Wit replacement series experiment (relative yield, relative yield total, plant height, aggressivity values) with S. shortii, S. altissima, and Festuca arundinacea (common competitor) suggested the following competitive hierarchy: S. altissima = F. arundinacea > S. shortii. Using classical growth analysis, we found that the competitive hierarchy was related closely to components of plant size (dry mass, height, leaf area, leaf area duration) and not to relative growth rate or any of its components (net assimilation rate, leaf area ratio, leaf weight ratio, specific leaf area). Solidago shortii allocated proportionately more dry mass to roots (but not to rhizomes) and had significantly greater root/shoot and (root + rhizome)/shoot ratios than did S. altissima. Thus, while the morphological traits of S. shortii enable it to tolerate drier habitats than S. altissima, in moist sites S. shortii easily would be overtopped and shaded out by S. altissima. Low competitive ability may be one of several factors contributing to the narrow endemism of S. shortii.

Defining transient and persistent seed banks in species with pronounced seasonal dormancy and germination patterns

The most often used time-line for distinguishing a transient seed bank from a persistent seed bank is one calendar year. Thus, species whose seeds live in or on the soil for ,1 year have a transient seed bank, whereas those whose seeds live for

Growth and reproduction of the invasive Ligustrum sinense and native Forestiera ligustrina (Oleaceae): Implications for the invasion and persistence of a nonnative shrub

1 year have a persistent seed bank. However, dormancy cycling of seeds buried in soil has not been given due consideration in these models. When dormancy cycling is considered, it is shown that seeds of both autumn-germinators and spring-germinators are in the dormant state when they are 1 year old. Thus, unless the seeds live until at least the second germination season (i.e. usually 16–18 months following dispersal), they are, in effect, part of a transient seed bank, having lived through only one germination season. We propose that for seeds of such species to be considered part of a short-term persistent seed bank, they should remain viable and germinable until at least the second germination season, and to be part of a long-term persistent seed bank, until at least the sixth germination season. Our definitions are applicable to seeds with physiological, physical or morphophysiological dormancy, which often require .1 year after maturity to come out of dormancy in nature. We discuss modifications of the seedling emergence method for detection of a soil seed bank, so that they correspond to our definitions of seed-bank strategies.

Effects of competition from introduced plants on establishment, survival, growth and reproduction of the rare plant Solidago shortii (Asteraceae)

Ligustrum sinense (Oleaceae) is an invasive shrub in the southeastern United States that was introduced from China. In middle Tennessee, the species grows with Forestiera ligustrina (Oleaceae), a shrub native to the southeastern United States, in the redcedar and/or hardwood forests surrounding cedar (limestone) glades. Here we compare the growth and reproduction of the two species and identify attributes that might influence the invasiveness and persistence of L. sinense. Plants of both species were sampled along the woodland edges of cedar glades and in the (primarily) redcedar forest at Stones River National Battlefield, Rutherford County, Tennessee, between March 2000 and February 2001. MANOVAs ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Germination ecophysiology of the western North American species Osmorhiza depauperata (Apiaceae): implications of preadaptation and phylogenetic niche conservatism in seed dormancy evolution

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Seed dormancy in Trillium camschatcense (Melanthiaceae) and the possible roles of light and temperature requirements for seed germination in forests

\end{document} ) indicated significant differences between species and habitats for several of the 23 traits measured in the study. Regardless of the habitat, L. sinense had a more treelike growth form—higher leaf area ratio (leafiness), leaf mass ratio (investment in leaf biomass), stem elongation rate, and number of fruits per ramet—and a lower percentage of insect‐damaged leaves and leaf abscission rate than F. ligustrina. Height and leaf areas of L. sinense plants growing in the woods were greater than those of L. sinense plants growing along the glade and greater than those of F. ligustrina plants growing in both habitats. Branch architecture did not differ appreciably between the species. Ligustrum sinense appears to possess a competitive advantage over F. ligustrina because of its greater ability to spatially and temporally capture light, a phenomenon that may lead to higher photosynthetic capacity and resource‐use efficiency, and because of the higher fruit production we observed.

Vegetation Change in a Former Chestnut Stand on the Cumberland Plateau of Tennessee during an 80-year Period (1921–2000)

Abstract Field and glasshouse studies investigated the effects of the introduced species Coronilla varia and Festuca arundinacea on establishment, survival, growth and reproduction of the federally-listed, endangered Solidago shortii (Asteraceae). All vegetation (mostly C. varia ) in plots with S. shortii was removed in May 1993, and the plots were kept free of vegetation (except S. shortii ) until September 1997 (treatment plots). Litter was removed from treatment plots each May 1993–1997. Neither vegetation nor litter was removed from control plots. Number of flowering and nonflowering ramets (stems) did not differ significantly between treatment and control plots in 1992 (year before vegetation removal). In treatment plots, number of flowering ramets of S. shortii increased significantly between 1992 and 1993 and then remained nearly constant from 1993 to 1996. In control plots, number of flowering ramets remained nearly constant from 1992 to 1996, and it was significantly lower than that in treatment plots from 1993 to 1996. Number of nonflowering ramets progressively increased in treatment plots from 1993 to 1996, while it remained nearly constant in control plots. Seedlings of S. shortii established only in treatment plots. Three percent of 1322 plants marked as seedlings in May 1994 were alive in September 1997, and about 0.4% of them had flowered by this date. At the end of four growing seasons, 36, 23, 18, 10 and 8% of the 39 surviving plants were in 3–10, 11–20, 21–30, 31–40 and 41–50 cm height classes, respectively; 5% of the plants were >50 cm tall. In a replacement series experiment, relative yield (RY) of S. shortii was significantly lower than the expected RY, whereas that of F. arundinacea was significantly higher than the expected RY. Relative yield total did not differ from one. The aggressivity value of S. shortii was significantly lower than that of F. arundinacea . Significantly fewer individuals of S. shortii flowered under inter- than under intraspecific competition. Thus, seedling establishment and vigor of S. shortii is highest in the absence of competitors, and future management practices will need to take this into account. ©

SHORT COMMUNICATION Increased sensitivity to green light during transition from conditional dormancy to nondormancy in seeds of three species of Solidago (Asteraceae)

Osmorhiza aristata is an herbaceous perennial that grows primarily in Japan, through southern China, to the Himalayas. It closely resembles the eastern North American species O. claytonii and O. longistylis, and, together, the three species are an example of the well-known North American-Asian pattern of disjunction. Requirements for dormancy break and embryo growth were determined for seeds of O. aristata collected in Japan during the summers of 1998-2000. Embryos in fresh seeds were ca. 0.5 mm long, and they had to grow to 9 mm before the radicle emerged from the mericarp. Embryo growth and germination occurred during cold stratification at 5°C, the optimum temperature for germination. Gibberellic acid did not substitute for cold stratification. Thus, O. aristata seeds have deep complex morphophysiological dormancy (MPD). The type of MPD in O. aristata is similar to that in two western North American congeners but different from that in eastern North American congeners (nondeep complex MPD). Mapping the types of MPD onto a phylogeny of the genus suggests that nondeep complex MPD is derived from deep complex MPD. Although eastern North American-Asian disjuncts often exhibit morphological stasis, the taxa may differ greatly in physiological traits, such as seed dormancy.