Clonal expansion and seedling recruitment of Oregon grape (Berberis nervosa) in Douglas-fir (Pseudotsuga menziesii) forests: comparisons with salal (Gaultheria shallon)

Huffman, David W.; Tappeiner, John C.

doi:10.1139/x97-150

Cited by 18 publications

(9 citation statements)

References 15 publications

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“…At the FP and SI sites, ramet-size distribution was skewed toward larger sizes in the gap stands where relative PARs were significantly greater than those in the closed-canopy stands. Similar patterns have been reported for other clonal understory trees (Huffman 1997;Pancer-Koteja et al 1998;Kanno and Seiwa 2004). High light condition is expected to enhance individual ramet growth and cause a shift in size distribution toward larger sizes.…”

Section: Discussionsupporting

confidence: 79%

Patch structure and ramet demography of the clonal tree, Asimina triloba, under gap and closed-canopy

et al. 2007

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Clonal understory trees develop into patches of interconnected and genetically identical ramets that have the potential to persist for decades or centuries. These patches develop beneath forest canopies that are structurally heterogeneous in space and time. Canopy heterogeneity, in turn, is responsible for the highly variable understory light environment that is typically associated with deciduous forests. We investigated what aspects of patch structure (density, size structure, and reproductive frequency of ramets) of the clonal understory tree, Asimina triloba, were correlated with forest canopy conditions. Specifically, we compared A. triloba patches located beneath closed canopies and canopy gaps. We also conducted a three-year demographic study of individual ramets within patches distributed across a light gradient. The closed canopy-gap comparison demonstrated that the patches of A. triloba had a higher frequency of large and flowering ramets in gaps compared to closed-canopy stands, but total ramet density was lower in gaps than in closed canopy stands. In the demographic study, individual ramet growth was positively correlated with light availability, although the pattern was not consistent for all years. Neither ramet recruitment nor mortality was correlated with light conditions. Our results indicate that the structure of A. triloba patches was influenced by canopy condition, but does not necessarily depend on the responses of ramets to current light conditions. The lack of differences in ramet recruitment and mortality under varying canopy conditions is likely to be a primary reason for the long-term expansion and persistence of the patches. The primary benefit of a positive growth response to increasing light is the transition of relatively small ramets into flowering ramets within a short period of time.

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Section: Discussionsupporting

confidence: 79%

Patch structure and ramet demography of the clonal tree, Asimina triloba, under gap and closed-canopy

et al. 2007

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“…Though both species are rhizomatous, evergreen, perennial shrubs, Mahonia probably has much less potential for clonal spread (Huffman and Tappeiner 1997). Because of greater recruitment into an apparently wider range of acceptable seedling microsites for the larger-seeded Mahonia than for Gaultheria Tappeiner 1997, USDA 1974), Mahonia may be able to increase more by seedlings after further forest management in ML than in MT owing to less…”

Section: Autecological Considerationsmentioning

confidence: 99%

Effects of forest management on understory and overstory vegetation: a retrospective study.

Thysell¹,

Carey²

2000

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Management for wood production through long rotations and thinning (MT) and management for biodiversity through legacy retention, protection, and no subsequent manipulation (ML) are two approaches to managing second-growth forests in the Pacific Northwest. We describe how these two strategies have affected tree size, tree density, and native and exotic vascular plant diversity and abundance.Keywords: Diversity, second-growth, Douglas-fir, Pseudotsuga menziesii, understory vegetation, species richness, forest development, thinning, legacies. SummaryWe examined understory and overstory vegetation in two proximate tracts of Douglas-fir (Pseudotsuga menziesu) forests with divergent management histories. The two tracts regenerated from harvest of old growth in the 1920s (MT) and 1930s (ML): MT subsequently was thinned twice and contained little coarse woody debris (CWD) and few snags; ML received no management after harvest with retention of some live and dead trees and contained moderate CWD, snags, and residual trees. We compared tree density, tree size, tree size-class diversity, understory species richness and abundance, and Shannon index of vascular plant diversity (H') in the two tracts. We performed a Bray-Curtis ordination to more fully illustrate variation in the understory communities.The MT tract had fewer and larger trees and had higher tree size-class diversity than ML. Species richness and diversity were significantly higher in MT than in ML. Total vascular plant species richness in MT (94 species) was twice that in the more densely stocked ML (47 species). Average total understory cover was much higher in MT (88 percent) than in ML (34 percent). Both tracts lacked shade-tolerant understory trees and had minimal foliage height diversity. Numerous exotic species were found in MT, but these were virtually absent in ML.Plant communities in the two tracts differed qualitatively and quantitatively, and current conditions will differentially influence plant composition and structure after future silvicultural entries. Forest processes such as crown differentiation, decadence, and understory development are amenable to management and suggest hypotheses about development of late-seral attributes in such stands. Due to lack of legacy trees and CWD in MT, crown differentiation will occur solely within the current cohort; CWD enhancement by tree felling would reduce stand density to unacceptably low levels. Future thinnings in MT may result in further increase of already-dominant clonal understory species that, along with lack of CWD as nurse logs, could delay establishment of a shade-tolerant understory and retard development of a diverse foliage height profile. In ML, crown differentiation is less than in MT but is augmented by residual trees. The amount of CWD in ML is greater than in MT; unlike MT, live-tree densities in ML permit CWD augmentation while retaining high stocking levels. After future thinnings, shade-tolerant trees, shrubs, and herbs should be more likely to establish in ML because of less compet...

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“…As resource availability increases either through tree mortality during natural stand development or because of silvicultural thinning, many clonal herbs and shrubs increase in abundance, presumably by lateral growth (Tappeiner and Alaback 1989;Huffman et al 1994;Halpern and Spies 1995;Huffman and Tappeiner 1997;Lezberg 1998;Thomas et al 1999). Thus, for understory herbs, the dynamics of populations during stand development and the abundance of species in older or thinned stands is strongly influenced by two characteristics related to clonal growth: ability to survive through the dense canopy stage and effectiveness in expansion as conditions become more favorable.…”

Section: Introductionmentioning

confidence: 99%

Clonal development of Maianthemum dilatatum in forests of differing age and structure

Lezberg¹,

Halpern²,

Antos³

2001

Can. J. Bot.

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Abstract:The development of a dense tree layer in young coniferous stands can suppress understory plants, leading to very low herb abundance and diversity. In this study, clonal development of the rhizomatous herb Maianthemum dilatatum (Wood) Nels & Macbr. was compared among four types of coniferous forest (young, closed canopy; young, silviculturally thinned; mature; and old growth) on the western Olympic Peninsula, Washington. We predicted that (i) ramet turnover would be lowest, (ii) clonal fragment size would be smallest, and (iii) allocation of resources to leaves would be greatest in young, closed-canopy forests, and that these traits would increase (or decrease for leaves) as understory conditions became more favorable with stand development or thinning. The low frequency of new ramets in young, closed-canopy stands supported the first prediction. The second prediction was also supported: lateral spread and rhizome mass were smallest in these stands. However, allocation to leaves was not higher in dense young stands, indicating that Maianthemum does not respond to stress by increased investment in leaves. Clonal fragments in thinned, mature, and old stands showed no differences in traits, suggesting that once tree canopies rise, canopy gaps form, or young stands are thinned, resource levels are favorable for clonal growth. Maianthemum appears to persist in dense, young stands by maintaining long-lived ramets that produce leaves annually, rather than by increasing rhizome spread, rhizome storage, or allocation to leaves.Key words: age structure, biomass allocation, canopy closure, forest herb, rhizome.Résumé : Le développement d'une dense canopée dans les jeunes peuplements de conifères peut supprimer la végéta-tion de sous-bois et conduire à de très faibles abondances et diversités de petites plantes herbacées. Dans cette étude, les auteurs comparent le développement clonal d'une plante herbacée, le Maienthemum dilatatum (Wood) Nels & Macbr., dans quatre types de forêts conifériennes (jeune à canopée fermée, jeune éclaircie par sylviculture, mature, surannée), situés dans la péninsule Olympique occidentale de l'état de Washington. Les auteurs ont prédit que (i) le cyclage des ramettes serait le plus faible, (ii) la dimension des rameaux clonaux serait la plus faible, et (iii) l'allocation aux feuilles serait la plus élevée dans les jeunes forêts à canopée fermée, et que ces caractéristiques augmenteraient (ou diminueraient) à mesure que les conditions de sous-bois deviendraient plus favorables avec le développement ou l'éclairci du peuplement. La faible fréquence des nouvelles ramettes dans les peuplements jeunes à canopée fermée supportent la première prédiction. La seconde prédiction s'avère également juste : le développement latéral et la masse de rhizome sont plus faibles dans ces peuplements. Cependant, l'allocation aux feuilles n'est pas plus forte dans les jeunes peuplements denses, ce qui indique que le Maienthemum ne réagit pas à l'ombrage par un investissement accru dans les feuilles. Les fragme...

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Clonal expansion and seedling recruitment of Oregon grape (Berberis nervosa) in Douglas-fir (Pseudotsuga menziesii) forests: comparisons with salal (Gaultheria shallon)

Cited by 18 publications

References 15 publications

Patch structure and ramet demography of the clonal tree, Asimina triloba, under gap and closed-canopy

Patch structure and ramet demography of the clonal tree, Asimina triloba, under gap and closed-canopy

Effects of forest management on understory and overstory vegetation: a retrospective study.

Clonal development of Maianthemum dilatatum in forests of differing age and structure

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