Willow Canopy Research Articles

Growth and survival of riparian plantings in relation to Weeping Willow canopy in the Upper Hunter River

Ecological Management & RestorationVolume 9, Issue 2 p. 154-156 Growth and survival of riparian plantings in relation to Weeping Willow canopy in the Upper Hunter River Garreth Kyle, Garreth KyleSearch for more papers by this authorTatjana Schmidt, Tatjana SchmidtSearch for more papers by this authorJulia Cooke, Julia CookeSearch for more papers by this authorMichelle R. Leishman, Michelle R. LeishmanSearch for more papers by this author Garreth Kyle, Garreth KyleSearch for more papers by this authorTatjana Schmidt, Tatjana SchmidtSearch for more papers by this authorJulia Cooke, Julia CookeSearch for more papers by this authorMichelle R. Leishman, Michelle R. LeishmanSearch for more papers by this author First published: 14 July 2008 https://doi.org/10.1111/j.1442-8903.2008.00409.xCitations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume9, Issue2August 2008Pages 154-156 RelatedInformation

INCREASED WILLOW HEIGHTS ALONG NORTHERN YELLOWSTONE's BLACKTAIL DEER CREEK FOLLOWING WOLF REINTRODUCTION

Gray wolves (Canis lupus) were reintroduced into Yellowstone National Park in 1995–1996. In August 2004 we measured plant architecture of Geyer willow (Salix geyeriana) stems along three 100-m reaches of Blacktail Deer Creek in Yellowstone's northern elk (Cervus elaphus) winter range to evaluate changes in patterns of browsing and height growth following wolf reintroduction. Average browsing intensities (n = 3 stream reaches) of 100% in 1997 decreased to 0%–55% by 2003, whereas average stem heights of 25–74 cm in 1997 increased to 149–268 cm by 2003, indicating that willow height growth was inversely related to browsing intensity. In addition, average willow canopy cover over the streams increased from <5% in 1997 to 14%–73% in 2004. These findings were consistent with a hypothesis that increased willow heights following the 1995–1996 wolf reintroduction represent a trophic cascade involving wolves, elk, and deciduous woody vegetation.

Nurse Effects of Alpine Willows (Salix) Enhance Over-winter Survival at the Upper Range Limit of Fireweed, Chamerion Angustifolium

ABSTRACTShrubs may act as nurse plants by facilitating the establishment and/or survival of under-story herbaceous plants under stressful conditions. Such interactions may promote the movement of montane species into alpine plant communities. We studied potential nurse effects of alpine willow shrubs (Salix spp.) on fireweed (Chamerion angustifolium) at three life history stages: seed, established seedling, and adult. Mechanisms for nurse effects were assessed at each stage by placing transplants into modified microsites containing shade and wind protection, as well as into unmanipulated microsites in open meadow and willow under-story habitats. Seedling establishment occurred only under the willow canopy and even there was extremely rare. Willows and experimental microcosms that simultaneously increased shade and reduced wind velocity strongly promoted over-winter survival of established seedlings and adults. All adult transplants surviving over the winter persisted over the subsequent growing season. For seedling transplants, extremely high mortality in exposed plots over the winter limited our power to experimentally detect nurse effects during the next growing season. Results suggest that by promoting persistent snow cover over the winter, willows enhance survival of fireweed at its upper range limit, potentially favoring its spread into alpine habitats.

Soil Fungal Communities Underneath Willow Canopies on a Primary Successional Glacier Forefront: rDNA Sequence Results Can Be Affected by Primer Selection and Chimeric Data

Soil fungal communities underneath willow canopies that had established on the forefront of a receding glacier were analyzed by cloning the polymerase chain reaction (PCR)-amplified partial small subunit (18S) of the ribosomal (rRNA) genes. Congruence between two sets of fungus-specific primers targeting the same gene region was analyzed by comparisons of inferred neighbor-joining topologies. The importance of chimeric sequences was evaluated by Chimera Check (Ribosomal Database Project) and by data reanalyses after omission of potentially chimeric regions at the 5'- and 3'-ends of the cloned amplicons. Diverse communities of fungi representing Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota were detected. Ectomycorrhizal fungi comprised a major component in the early plant communities in primary successional ecosystems, as both primer sets frequently detected basidiomycetes (Russulaceae and Thelephoraceae) forming mycorrhizal symbioses. Various ascomycetes (Ophiostomatales, Pezizales, and Sordariales) of uncertain function dominated the clone libraries amplified from the willow canopy soil with one set of primers, whereas the clone libraries of the amplicons generated with the second primer set were dominated by basidiomycetes. Accordingly, primer bias is an important factor in fungal community analyses using DNA extracted from environmental samples. A large proportion (>30%) of the cloned sequences were concluded to be chimeric based on their changing positions in inferred phylogenies after omission of possibly chimeric data. Many chimeric sequences were positioned basal to existing classes of fungi, suggesting that PCR artifacts may cause frequent discovery of new, higher level taxa (order, class) in direct PCR analyses. Longer extension times during the PCR amplification and a smaller number of PCR cycles are necessary precautions to allow collection of reliable environmental sequence data.

Sources of spatial and temporal heterogeneity in the colonization of an alpine krummholz environment by the weedy subalpine plant Chamerion angustifolium (fireweed)

Plant–plant interactions may increase or reduce the impact of abiotic stress on species' distributions, depending on the balance between competition and facilitation. We report on the role of a willow ( Salix ) shrub canopy in mediating the importance of drought stress for performance at seedling and adult life stages of the herbaceous wildflower, Chamerion angustifolium L. (fireweed). Willows form the vegetative boundary (krummholz) between subalpine and alpine life zones in the Rocky Mountains. Chamerion angustifolium is a weedy pioneer species common in subalpine vegetation and advancing upward into the krummholz in the central Rocky Mountains. A mosaic of soil moisture variation dictated spatial patterns of seed germination and seedling survival in C. angustifolium in the absence of willows. However, willows restricted the capacity of C. angustifolium to exploit natural patches of soil moisture during establishment. Seed germination, seedling survival, and net establishment success increased markedly with soil water supply in the open, but not under the willow canopy. For mature plants, willows restricted photosynthesis at the peak of the growing season when rainfall was frequent, but ameliorated the daily decline in leaf water status under drought late in the season. Results suggest that the impact of willows on desiccation stress in alpine populations of fireweed varies with life history stage and phenology.

Radiation fluxes and canopy transmittance: Models and measurements inside a willow canopy

Upward and downward fluxes of photosynthetically active and broadband solar radiation, and the transmittance of direct solar radiation measured at different heights inside a willow (Salix viminalis) canopy are compared with modeling results. Two approaches are used for modeling the radiation field inside the canopy: solving the radiative transfer equation using the exact kernel discrete ordinates method and a Monte Carlo model. The measured and modeled canopies include a 1‐year‐old willow coppice with leaf area index (LAI) = 5 and a 4‐year‐old coppice with LAI = 8. Biometrical data used in the models are taken from detailed measurements of canopy structure; measured fluxes are used as boundary conditions. An attempt is made to include the effect of clumping on the penetration of direct solar radiation into the radiative transfer model. All models agreed well with measurement results; enhancement of modeled fluxes due to inclusion of clumping depended on the height inside the canopy while the distribution of leaf inclination angle had a minimal effect on the radiation regime of the stand.

Grazing History Affects Willow Communities in a Montane Riparian Ecosystem

This study was conducted to compare data from 12 grazed and ungrazed areas and to examine the impacts of grazing treatments on a montane willow community during an 11-year period. Data were collected on willow canopy cover, species diversity, height, and stem density in a montane riparian ecosystem between 1988 and 1999 from 4 grazing treatments: long-term grazing (since the early 1900s), long-term grazing exclusion (exclosures built in the 1950s), recent grazing (sections of exclosures opened in 1988), and recent grazing exclusion (exclosures built in 1988). Willow canopy cover increased significantly for all treatments through time, with the recent grazing exclusion treatment becoming similar to that of the long-term exclusion treatment within 5 years. Species diversity was greatest in the long-term grazed treatment. Willow height averaged over treatments increased from 1988 to 1997 (P = 0.0001), but did not increase significantly after that. Height in the long-term exclosure averaged over time from 1988 to 1997 was 1.5 times greater than in the long-term grazing treatment. Stem density of willows was significantly greater in the recent exclosure than in the long-term exclosure (P = 0.008, 180%) and recent grazing treatments (P = 0.02, 120%). Recent grazing exclusion resulted in the greatest increase in canopy cover, height growth, and stem density during the 11 years of study, indicating that these variables respond positively to removal of livestock grazing. Results suggest that continued long-term grazing exclusion may lead to a closed canopy, lower willow species diversity, reduction in new stem height growth, and reduced stem recruitment. Information on the dynamics of willow growth under different grazing treatments should help resource managers determine appropriate livestock utilization levels in similar riparian areas, and develop management plans for these important ecosystems.

Grazing History Affects Willow Communities in a Montane Riparian Ecosystem

This study was conducted to compare data from 12 grazed and ungrazed areas and to examine the impacts of grazing treatments on a montane willow community during an 11-year period. Data were collected on willow canopy cover, species diversity, height, and stem density in a montane riparian ecosystem between 1988 and 1999 from 4 grazing treatments: long-term grazing (since the early 1900s), long-term grazing exclusion (exclosures built in the 1950s), recent grazing (sections of exclosures opened in 1988), and recent grazing exclusion (exclosures built in 1988). Willow canopy cover increased significantly for all treatments through time, with the recent grazing exclusion treatment becoming similar to that of the long-term exclusion treatment within 5 years. Species diversity was greatest in the long-term grazed treatment. Willow height averaged over treatments increased from 1988 to 1997 (P = 0.0001), but did not increase significantly after that. Height in the long-term exclosure averaged over time from 1988 to 1997 was 1.5 times greater than in the long-term grazing treatment. Stem density of willows was significantly greater in the recent exclosure than in the long-term exclosure (P = 0.008, 180%) and recent grazing treatments (P = 0.02, 120%). Recent grazing exclusion resulted in the greatest increase in canopy cover, height growth, and stem density during the 11 years of study, indicating that these variables respond positively to removal of livestock grazing. Results suggest that continued long-term grazing exclusion may lead to a closed canopy, lower willow species diversity, reduction in new stem height growth, and reduced stem recruitment. Information on the dynamics of willow growth under different grazing treatments should help resource managers determine appropriate livestock utilization levels in similar riparian areas, and develop management plans for these important ecosystems.

Willow Canopies and Plant Community Structure along an Alpine Environmental Gradient

We examined the impact of Salix lapponum canopies on plant community structure in five sites along a climatic gradient in a glacier foreland in alpine south Norway. Species richness is lower inside canopies compared to outside in climatically relatively benign communities, while species richness is not affected by canopies in the most severe communities closest to the glacier. Differences in species composition inside and outside canopies, as judged by detrended correspondence analysis, are greater in the benign communities compared to the severe communities. Variation in the differences in species richness or composition outside and inside canopies within a community is related to differences in the reduction of photosynthetically active radiation (PAR) by canopies in only one community. Canopy size does not explain differences in species richness or composition between outside and inside canopies in any except one benign community. Our results suggest that species responses to canopies are individualistic, and that at the whole-community level negative and positive impacts of canopies on species occurrences cancel each other out in severe communities, whereas in benign communities negative effects dominate slightly over positive ones in their effects on species persistence inside canopies.

Willow Canopies and Plant Community Structure along an Alpine Environmental Gradient

Willow Canopies and Plant Community Structure along an Alpine Environmental Gradient

Fungal colonization of shrub willow roots at the forefront of a receding glacier.

Shrub willows ( Salix spp.) form associations with arbuscular mycorrhizal (AM), ectomycorrhizal (EM) and dark septate endophytic (DSE) fungi. Willow root colonization by these three types of fungi was studied on a deglaciated forefront of Lyman Glacier, Washington, USA. Root colonization was low; less than 1% of the root length was colonized by AM and 25.6% by DSE. EM colonized 25% of the root tips and 19.4% of the root length. AM and DSE colonization were not related to distance from the present glacier terminus or to canopy cover. EM colonization increased with distance from the glacier terminus based on gridline intercept data but not on root tip frequency data. Availability of propagules in the substrate was low, but numbers of propagules increased with distance from the glacier terminus. The EM communities were dominated by three ascomycetes showing affinity to Sordariaceae in BLAST analyses. Other frequent taxa on the glacier forefront included species of Cortinariaceae, Pezizaceae, Russulaceae, Thelephoraceae and Tricholomataceae. When occurrence of individual taxa was used as a response variable to canopy cover, distance from the glacier terminus, and their interaction, four different fungal guilds were identified: 1) fungi that did not respond to these environmental variables; 2) fungi that occurred mainly in intercanopy areas and decreased with distance from the glacier terminus; 3) fungi that were insensitive to canopy cover but increased with distance from the glacier terminus; 4) fungi that occurred mainly under willow canopies and increased with distance from the glacier terminus. We suggest that fungal colonization is mainly limited by fungal propagule availability. Environmental conditions may also limit successful establishment of plant-fungus associations. We propose that the four EM guilds partly explain successional dynamics. The initial EM community comprises fungi that tolerate low organic matter and nitrogen environment (first and second guilds above). During later community development, these fungi are replaced by those that benefit from an increased organic matter and nitrogen environment (third and fourth guilds above).

Effects of willow canopies on plant species performance in a low-alpine community

It is believed that abiotic, rather than biotic, factors are ofparamount importance to the performance of plants in alpine and arctichabitats.This study examines how Salix lapponum affects 15associated species by comparing individual growth and reproductive performanceof adult plants growing inside and outside shrub canopies. The study alsoincludes experimental removal of Salix lapponum shrubs,andmeasurements of shoot density of five species inside and outside intactcanopies. Mean above-ground plant weight of nine species was significantlyhigher inside canopies compared to outside. Mean leaf number inside canopieswassignificantly higher for two species, and total seed number was significantlyhigher inside for one species. Mean leaf number was significantly lower insidecanopies compared to outside for one species. Mean seed weight wassignificantlylower inside canopies for one species. Removal of Salixlapponum shrubs increased bulbil weight of Bistortavivipara and seed number and plant weight of Euphrasiafrigida. These results suggest that canopy removal relaxedcompetition. Shoot density was substantially higher outside canopies comparedtoinside for four species and slightly higher outside for one species. Soilmoisture, soil organic content, soil pH, and temperature inside canopies werenot significantly different from outside, whereas photosynthetically activeradiation (PAR) was markedly reduced inside canopies. Increased growth insidecanopies is likely a compensatory mechanism to decreased PAR, which enableplants inside canopies to achieve reproductive outputs that equals those onoutside plants. The lower plant density inside canopies is probably caused byreduced germination and establishment possibilities there, due to reduced PARand higher litter accumulation.

Spatial correlations of Diceroprocta apache and its host plants: evidence for a negative impact from Tamarix invasion

Abstract 1. The hypothesis that the habitat-scale spatial distribution of the Apache cicada Diceroprocta apache Davis is unaffected by the presence of the invasive exotic saltcedar Tamarix ramosissima was tested using data from 205 1-m2 quadrats placed within the flood-plain of the Bill Williams River, Arizona, U.S.A. Spatial dependencies within and between cicada density and habitat variables were estimated using Moran's I and its bivariate analogue to discern patterns and associations at spatial scales from 1 to 30 m. 2. Apache cicadas were spatially aggregated in high-density clusters averaging 3 m in diameter. A positive association between cicada density, estimated by exuvial density, and the per cent canopy cover of a native tree, Goodding's willow Salix gooddingii, was detected in a non-spatial correlation analysis. No non-spatial association between cicada density and saltcedar canopy cover was detected. 3. Tests for spatial cross-correlation using the bivariate IYZ indicated the presence of a broad-scale negative association between cicada density and saltcedar canopy cover. This result suggests that large continuous stands of saltcedar are associated with reduced cicada density. In contrast, positive associations detected at spatial scales larger than individual quadrats suggested a spill-over of high cicada density from areas featuring Goodding's willow canopy into surrounding saltcedar monoculture. 4. Taken together and considered in light of the Apache cicada's polyphagous habits, the observed spatial patterns suggest that broad-scale factors such as canopy heterogeneity affect cicada habitat use more than host plant selection. This has implications for management of lower Colorado River riparian woodlands to promote cicada presence and density through maintenance or creation of stands of native trees as well as manipulation of the characteristically dense and homogeneous saltcedar canopies.

Influence of a willow canopy on tree seedling establishment for wetland restoration

Black willow (Salix nigra) is a well-known pioneer species of disturbed riparian areas. It competes for nutrients, light, and water, but it may also act as a “nurse” crop, providing shelter for other species from high light and temperature; so, the overall effect on species planted under a willow canopy could be positive or negative. This experiment examined the response of container-grown seedlings of four tree species outplanted into three habitats: 1) an existing willow stand, 2) a similar habitat, but with the willow canopy removed, and 3) an adjacent grass-dominated area free of willow. After three years, survival rates of overcup oak (Quercus lyrata), baldcypress (Taxodium distichum), and water hickory (Carya aquatica) were not reduced under the willow canopy relative to the other two treatments. Laurel oak (Q. laurifolia) was killed by several floods during the first growing season. Height of baldcypress seedlings planted under a willow canopy was less than for seedlings where the willow had been removed. Water hickory and overcup oak height were not affected by the willow canopy. Elevation of the planting sites, indicating probable soil wetness, was a good indicator of survival when used in conjunction with the species flood-tolerance. The existing willow stand was not detrimental to survival of three of the outplanted tree species. Thus, willow removal is unnecessary for successful outplanting, saving time and money.

Effects of a willow overstory on planted seedlings in a bottomland restoration

Four bottomland tree species (green ash, bald cypress, water tupelo, and swamp chestnut oak) were planted under four levels of willow canopy (intact canopy, 60% thinned with herbicide, complete control with herbicide, and complete mechanical removal plus control with herbicide). Through age 5, species selection rather than canopy control treatment was the dominant factor in determining regeneration success. About 55% of the cypress and green ash seedlings were surviving at age 5, versus 17 and 27% of water tupelo and swamp chestnut oak, respectively. Green ash was significantly taller (at 3.7 m) than all other species at age 5. The willow canopy provided minor growth benefits during the first 2 years by ameliorating herbaceous competition, hydrology, and soil temperature. However, by age 5, there were no significant differences in seedling heights among the canopy treatments. We believe that an improved strategy would involve removal of the willow canopy 2 years after planting, when the seedlings begin to exhibit substantial height-growth potential and are, thus, better prepared to respond.

Statistical treatment of sunfleck length inside willow coppice

Different sunfleck characteristics, length and number of sunflecks per metre and sunfleck fractional area, were measured at different depths inside willow ( Salix viminalis) canopy. All these characteristics depend on the pathlength of the direct solar radiation beam into the canopy, τ= L/sin h, where L is the downward cumulative leaf area index and h is the solar elevation. The mean sunfleck length l S decreases exponentially with τ. The maximum length of short sunflecks (length <6 cm) decreases linearly with τ, but not exponentially. Like the number of short sunflecks, the total number of sunflecks increases with τ, reaches a maximum value of 10–12 sunflecks m −1 at τ=2.5 and then decreases slowly to zero at τ=6. The vertical profiles of the sunfleck fractional area are different for long (length >6 cm) and short sunflecks. The fractional area of long sunflecks decreases with τ exponentially; the fractional area of short sunflecks, k SS, can be approximated by the formula k SS=0.19 τ exp(−0.15 τ 2), and the fractional area of all sunflecks k S, by the formula k S=exp(−0.18 τ 2). Within the canopy, direct solar radiation is present in two areas — in sunflecks and in penumbra. The total flux of direct solar radiation in penumbra is smaller than it is in sunflecks and reaches its maximum value of 50% at the pathlength τ=2. There exists a good correlation with R 2=0.94 between the fractional area of umbra, k U, and the fractional area of sunflecks, k S, which can be fitted by the exponential formula k U=0.63 exp(−2.30 k S).

Effects of Established Willows on Primary Succession on Lyman Glacier Forefront, North Cascade Range, Washington, U.S.A.: Evidence for Simultaneous Canopy Inhibition and Soil Facilitation

The effect of established shrub willows (Salix commutata and S. phylicifolia) was tested in a primary successional ecosystem at Lyman Glacier forefront in the North Cascade Range (Washington, U.S.A.). To examine the hypothesis that early successional plant individuals form centers of establishment for subsequent vascular plant colonizers, two experiments were conducted to assay the effect of shrub willows on the establishment and survival of indigenous plants. First, the occurrence of indigenous plant species under willow canopies was compared with their occurrence beyond the canopies (experiment 1). Second, the separate effects of willow canopies and associated soils on germinant emergence and survival of an indigenous taxon, Pinus contorta, were evaluated (experiment 2). Both experiments indicated that the shrub willows do not serve as nuclei that facilitate the establishment of new, emerging plant individuals. In experiment 1, the willow canopy had no effect on the observed frequency of most indigenous taxa. Five species, however, were negatively associated with the willow canopies. In experiment 2, willow canopies inhibited the germinant emergence of P. contorta. The greatest emergence occurred in soils transferred from beneath willow canopies to areas beyond the canopies. Results from the two experiments suggest that while the willow canopy is either neutral or inhibitory in its effect on establishment of indigenous plants, the soil developing beneath the willow can actually be a positive factor towards plant establishment.

Effects of Established Willows on Primary Succession on Lyman Glacier Forefront, North Cascade Range, Washington, U.S.A.: Evidence for Simultaneous Canopy Inhibition and Soil Facilitation

The effect of established shrub willows (Salix commutata and S. phylicifolia) was tested in a primary successional ecosystem at Lyman Glacier forefront in the North Cascade Range (Washington, U.S.A.). To examine the hypothesis that early successional plant individuals form centers of establishment for subsequent vascular plant colonizers, two experiments were conducted to assay the effect of shrub willows on the establishment and survival of indigenous plants. First, the occurrence of indigenous plant species under willow canopies was compared with their occurrence beyond the canopies (experiment 1). Second, the separate effects of willow canopies and associated soils on germinant emergence and survival of an indigenous taxon, Pinus contorta, were evaluated (experiment 2). Both experiments indicated that the shrub willows do not serve as nuclei that facilitate the establishment of new, emerging plant individuals. In experiment 1, the willow canopy had no effect on the observed frequency of most indigenous taxa. Five species, however, were negatively associated with the willow canopies. In experiment 2, willow canopies inhibited the germinant emergence of P. contorta. The greatest emergence occurred in soils transferred from beneath willow canopies to areas beyond the canopies. Results from the two experiments suggest that while the willow canopy is either neutral or inhibitory in its effect on establishment of indigenous plants, the soil developing beneath the willow can actually be a positive factor towards plant establishment.

Forest cover selection and activity of cow moose in summer

Although thermal cover receives attention from managers, variations in data regarding its use by ungulates hinders development of effective cover guidelines. Authors examined patterns of habitat selection and activity of radio-collared cow moose Alces alces Linnaeus, 1758 to determine if these 2 parameters were influenced by ambient thermal environment. Cow moose used sites with relatively denser forest canopies when condition of heat stress existed in open areas. Use of open areas did not change with ambient temperature; some sites classed as open on forest cover maps, however, had willow canopies capable of providing thermal cover. An increase in the use of open sites from 11.00 to 24.00 hr corresponded to a simultaneous decrease in the likelihood of thermal stress in such areas; predator-avoidance was deemed unlikely to explain observed behaviour. Moose decreased activity and distance traveled between successive locations during hot periods. Summer thermal cover is a selected, manageable component of moose habitat in southern British Columbia.

Genet Disintegration in Filipendula Ulmaria: Consequences for Population Dynamics and Vegetation Succession

1 The dynamics of populations of Filipendula ulmaria during succession in an abandoned meadows in the centre of the Bialowieza Primeval Forest was studied over the period 1974-90. The growth and disintegration of individual genets was followed throughout succession. 2 In patches originally dominated by grasses and macroforbs, the number of genets increased rapidly to reach five to seven times the original number within about 8 years. A second increase in numbers was seen between 12 and 14 years, due to disintegration of the genets. In a patch dominated by sedges, the population grew slowly and the resulting small genets seldom disintegrated. 3 Expansion is followed by disintegration once critical size is attained. Change in size of genets and the ratio between generative and vegetative offspring resulted in the overall spatial structure changing from uniform to more clumped over the 17-year study period. 4 The number of ramets in a genet is correlated with the size and age of the genet. The growth and survivorship of new genets and genet fragments are limited by the gradually increasing necromass cover, and by the willow canopy. 5 Overall vegetation dynamics is strongly related to F. ulmaria populations in that: (a) the increase of abundance of F. ulmaria coincided with the start of succession; (b) the maximum abundance coincided with a transient stage in the succession from macroforbs to willow; (c) the decrease in abundance of F. ulmaria began when the meadow became dominated by willow. 6 The advancing senescence of Filipendula ulmaria genets, manifested in the necrosis of their senile parts, gives rise to free space within the genet area which is subsequently colonized by other species. The number of colonizers increases with the age and size of the genet, with continued species turnover taking place above 10 years of age. Senescence and disintegration of genets thus influence succession in abandoned meadows.