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Plant Density (plant + density)

Distribution by Scientific Domains

Life Sciences	67%
Earth and Environmental Science	27%
2 Other Domains	6%

Selected Abstracts

Effects of secondary tuber harvest on populations of devil's claw (Harpagophytum procumbens) in the Kalahari savannas of South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
Kristine M. Stewart
Abstract Devil's claw (Harpagophytum procumbens) is an internationally traded species that is harvested for its secondary tubers. Root extracts are used to treat arthritis and other inflammatory diseases. This study examined population structure, density, growth, mortality, and seed and fruit production in harvested and unharvested populations in the Kalahari savannas of South Africa over 4 years. Plant density and population structure differed significantly between overgrazed and grass-dominated areas, suggesting that the differences may be due to competition for water and nutrients. Experimental removal of secondary tubers (harvest) was not a significant factor for mortality in any of the harvested size classes. Harvest also did not affect growth, although plants in the 3,4 cm size class grew more in both the harvested and unharvested populations. Fruit production was variable; fruits matured only after sufficient rains. Under the conditions of this study, the species appears to be resilient to harvest, with both harvested and unharvested plants surviving. After harvest, both groups recovered and grew (on average) at the same rate. Because of the spatially variable habitat and the plasticity of the plants themselves, a large number of plants over a wide area are required to better understand the species' life history. Résumé La griffe du diable Harpagophytum procumbens est une espèce qui est commercialisée à l'échelle internationale; on en récolte les tubercules poussant sur les racines secondaires. Les extraits de racines sont utilisés pour traiter l'arthrite et d'autres maladies inflammatoires. Cette étude examine la structure de sa population, sa densité, sa croissance, sa mortalité et sa production de semences et de fruits chez les populations récoltées ou non des savanes du Kalahari en Afrique du Sud, pendant quatre ans. La densité des plantes et la structure des populations différaient significativement entre les zones surpâturées et celles où les herbes dominaient, ce qui suggère que les différences pourraient être dues à la compétition pour l'eau et les nutriments. Le prélèvement expérimental des tubercules secondaires (récolte) n'était un facteur significatif de mortalité dans aucune des classes de taille récoltées. La récolte n'affectait pas non plus la croissance, même si les plants de la classe de taille des 3,4 cm croissaient plus chez les populations aussi bien récoltées que non récoltées. La production de fruits était variable; les fruits n'arrivaient à maturité qu'après des pluies suffisantes. Dans les conditions où fut réalisée cette étude, les espèces ont semblé résilientes à la récolte, les plants récoltés survivant aussi bien que ceux qui ne l'avaient pas été. Après la récolte, les deux groupes se rétablissaient et croissaient (en moyenne) au même rythme. Étant donné que l'habitat est très variable selon les endroits et vu la plasticité des plantes elles-mêmes, il faut étudier un grand nombre de plantes sur une grande superficie pour mieux comprendre l'histoire complète de cette espèce. [source]

Short-term epidemic dynamics in the Cakile maritima,Alternaria brassicicola host,pathogen association

JOURNAL OF ECOLOGY, Issue 5 2001
Peter H. Thrall
Summary 1Studies combining within- and among-population processes are crucial for understanding ecological and co-evolutionary dynamics in host,pathogen interactions. We report on work over an 18-month period involving multiple beach populations of the plant Cakile maritima and its fungal pathogen Alternaria brassicicola along the south-east coast of Australia. 2Results from permanent transects replicated on several beaches show that disease incidence and prevalence vary significantly with plant age, class and distance from the sea, as well as time during the season. Plant density is also positively related to disease levels. 3Results from three subregions indicate that disease persistence depends on survival of infected plants behind the foredunes of protected beaches. Population extinction was more likely on beaches with greater wind exposure and sea access, with the latter also related to colonization consistent with the dispersal of Cakile seeds via ocean currents. 4Although disease dynamics during the epidemic were similar across subregions, the severity of the epidemic varied significantly among these areas, suggesting that large-scale environmental factors may influence the timing and development of the epidemic. 5Estimates of synchrony in disease dynamics indicated that populations within a subregion were significantly correlated with respect to epidemic development. There was, however, no evidence for spatial synchrony in disease dynamics based on among-population covariances in disease prevalence and interbeach distances. Populations within a subregion were thus often at quite different phases of the epidemic at any given time. [source]

Revegetation Methods for High-Elevation Roadsides at Bryce Canyon National Park, Utah

RESTORATION ECOLOGY, Issue 2 2004
S. L. Petersen
Abstract Establishment of native plant populations on disturbed roadsides was investigated at Bryce Canyon National Park (BCNP) in relation to several revegetation and seedbed preparation techniques. In 1994, the BCNP Rim Road (2,683,2,770 m elevation) was reconstructed resulting in a 23.8-ha roadside disturbance. Revegetation comparisons included the influence of fertilizer on plant establishment and development, the success of indigenous versus commercial seed, seedling response to microsites, methods of erosion control, and shrub transplant growth and survival. Plant density, cover, and biomass were measured 1, 2, and 4 years after revegetation implementation (1995,1998). Seeded native grass cover and density were the highest on plots fertilized with nitrogen and phosphorus, but by the fourth growing season, differences between fertilized and unfertilized plots were minimal. Fertilizers may facilitate more rapid establishment of seeded grasses following disturbance, increasing soil cover and soil stability on steep and unstable slopes. However the benefit of increased soil nutrients favored few of the desired species resulting in lower species richness over time compared to unfertilized sites. Elymus trachycaulus (slender wheatgrass) plants raised from indigenous seed had higher density and cover than those from a commercial seed source 2 and 4 years after sowing. Indigenous materials may exhibit slow establishment immediately following seeding, but they will likely persist during extreme climatic conditions such as cold temperatures and relatively short growing seasons. Seeded grasses established better near stones and logs than on adjacent open microsites, suggesting that a roughened seedbed created before seeding can significantly enhance plant establishment. After two growing seasons, total grass cover between various erosion-control treatments was similar indicating that a variety of erosion reduction techniques can be utilized to reduce erosion. Finally shrub transplants showed minimal differential response to fertilizers, water-absorbing gels, and soil type. Simply planting and watering transplants was sufficient for the greatest plant survival and growth. [source]

Grazing without grasses: Effects of introduced livestock on plant community composition in an arid environment in northern Patagonia

APPLIED VEGETATION SCIENCE, Issue 1 2006
Mariana Tadey
Abstract Question: How does grazing intensity affect plant density, cover and species richness in an Patagonian arid ecosystem? Location: Monte steppe ecoregion, SW Argentina. Methods: I analysed the effect of grazing on plant density, cover and species richness using a stocking rate gradient within the same habitat. Six paddocks were used with stocking rates ranging between 0.002 , 0.038 livestock/ha. Plant density, species richness, plant cover and percentage of grazed branches were determined by sampling plots within each paddock. The percentage of grazed branches was used as an independent measurement of grazing intensity. Results: Higher stocking rates were related to lower plant density, species richness and plant cover. The paddock with the lowest grazing intensity had 86% more plants per unit area, 63% more plant cover and 48% higher species richness. The percentage of grazed branches and the quantity of dung increased with stocking rate. Conclusions: Introduced livestock seriously affect native vegetation in the Patagonian Monte. The damage observed in this xerophytic plant community suggests that plant adaptations to aridity do not provide an advantage to tolerate or avoid grazing by vertebrate herbivores in this region. Plant degradation in this arid environment is comparable to the degradation found in more humid ecosystems. [source]

The importance of plant root characteristics in controlling concentrated flow erosion rates

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2003
G. Gyssels
Abstract While it has been demonstrated in numerous studies that the aboveground characteristics of the vegetation are of particular importance with respect to soil erosion control, this study argues the importance of separating the influence of vegetation on soil erosion rates into two parts: the impact of leaves and stems (aboveground biomass) and the influence of roots (belowground biomass). Although both plant parameters form inseparable constituents of the total plant organism, most studies attribute the impact of vegetation on soil erosion rates mainly to the characteristics of the aboveground biomass. This triggers the question whether the belowground biomass is of no or negligible importance with respect to soil erosion by concentrated flow. This study tried to answer this question by comparing cross-sectional areas of concentrated flow channels (rills and ephemeral gullies) in the Belgian Loess Belt for different cereal and grass plant densities. The results of these measurements highlighted the fact that both an increase in shoot density as well as an increase in root density resulted in an exponential decrease of concentrated flow erosion rates. Since protection of the soil surface in the early plant growth stages is crucial with respect to the reduction of water erosion rates, increasing the plant root density in the topsoil could be a viable erosion control strategy. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Soil Temperature and Planting Depth Effects on Tef Emergence

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2009
S. Evert
Abstract Tef [Eragrostis tef (Zucc.) Trotter] is an annual C4 grass crop that originated in Ethiopia. It has potential as a grain crop in the Great Plains because of its tolerance to drought and high temperatures. In Ethiopia, tef seed is typically broadcast on the soil surface and lightly incorporated. Shallow planting depths are used because the seed is very small and emergence can be limited by soil crusting. If planting equipment is to be used, planting depth may be important for successful tef production. The objective of this study was to identify optimal depths and soil temperatures to aid in developing tef planting recommendations for the central Plains. Tef was planted at five depths (0, 0.6, 1.3, 2.5 and 5.0 cm) in pots filled with a silt loam soil, and pots were placed in growth chambers at four temperature regimes (day/night: 15/19 °C; 19/23 °C; 23/27 °C and 27/31 °C). No plants emerged from the 5.0-cm depth, so this depth was not included in the analysis. Emergence was greatest for planting depths of 0.6 and 1.3 cm and lower at 0 and 2.5 cm depths. Temperature did not affect final emergence, measured 21 days after planting (DAP), but did influence emergence rates during the first 9 DAP. Plant dry matter production increased as planting depth increased, but plant dry matter per pot was not different among planting depths greater than 0.9 cm, suggesting that compensation between plants across different plant densities began early in the plants' life cycles. Our results show that tef seed can emerge from depths between 0.6 and 1.3 cm and that soil temperatures below 19 °C can slow emergence but should not affect final stands. [source]

Fine-Scale Spatial Genetic Structure of the Distylous Primula veris in Fragmented Habitats

PLANT BIOLOGY, Issue 3 2007
F. van Rossum
Abstract: In Flanders (northern Belgium), the distylous self-incompatible perennial herb Primula veris is common, but mainly occurs in fragmented habitats. Distyly, which favours disassortative mating, is characterized in P. veris by two genetically determined floral morph types (pin or thrum). Using 18 polymorphic loci, we investigated fine-scale spatial genetic structure (SGS) and spatial distribution of the morphs within four populations from two regions that differ in degree of habitat fragmentation. We studied the contributions made by sexual reproduction and clonal propagation and compared the SGS patterns between pin and thrum morph types. Clonal growth was very restricted to a few individuals and to short distances. One population showed a non-random spatial distribution of the morphs. Pin and thrum individuals differed in SGS patterns at a small scale, suggesting intrapin biparental inbreeding, also related to high plant densities. This may be explained by partial self-compatibility of the pin morph combined with restricted seed dispersal and pollinator behaviour. There is an indication of more pronounced SGS when populations occur in highly fragmented habitats. From our findings, we may hypothesize disruption of the gene flow processes if these large populations evolve into patchworks of small remnants, but also a possible risk for long-term population survival if higher intrapin biparental inbreeding leads to inbreeding depression. Our study emphasizes the need for investigating the interactions between the heterostylous breeding system, population demographic and genetic structure for understanding population dynamics in fragmented habitats and for developing sustainable conservation strategies. [source]

Density-Induced Plant Size Reduction and Size Inequalities in Ethylene-Sensing and Ethylene-Insensitive Tobacco

PLANT BIOLOGY, Issue 2 2004
R. Pierik
Abstract: Plant competition for light is a commonly occurring phenomenon in natural and agricultural vegetations. It is typically size-asymmetric, meaning that slightly larger individuals receive a disproportionate share of the light, leaving a limited amount of light for the initially smaller individuals. As a result, size inequalities of such stands increase with competition intensity. A plant's ability to respond morphologically to the presence of neighbour plants with enhanced shoot elongation, the so-called shade avoidance response, acts against the development of size inequalities. This has been shown experimentally with transgenic plants that cannot sense neighbours and, therefore, show no shade avoidance responses. Stands of such transgenic plants showed a much stronger development of size inequalities at high plant densities than did wild type (WT) stands. However, the transgenic plants used in these experiments displayed severely hampered growth rates and virtually no response to neighbours. In order to more precisely study the impact of this phenotypic plasticity on size inequality development, experiments required plants that have normal growth rates and reduced, but not absent, shade avoidance responses. We made use of an ethylene-insensitive, transgenic tobacco genotype (Tetr) that has wild type growth rates and moderately reduced shade avoidance responses to neighbours. Here, we show that the development of size inequalities in monocultures of these plants is not affected unambiguously different from wild type monocultures. Plots of Tetr plants developed higher inequalities for stem length than did WT, but monocultures of the two genotypes had identical CV (Coefficient of Variance) values for shoot biomass that increased with plant density. Therefore, even though reduced shade avoidance capacities led to the expected higher size inequalities for stem length, this does not necessarily lead to increased size inequalities for shoot biomass. [source]

Effects of shade on root characters associated with lodging in wheat (Triticum aestivum)

ANNALS OF APPLIED BIOLOGY, Issue 3 2008
D.L. Sparkes
Abstract Previous work has shown that as the density of wheat plants increase, the spread of the root plate, root length and root number per plant decrease, leading to reduced anchorage strength and increased lodging susceptibility. The aim of this study was to determine which aspect of mutual plant shading [reduction of photosynthetically active radiation (PAR) or the ratio of red to far red light (R : FR)] is associated with this reduction in anchorage strength. Field experiments were conducted at Sutton Bonington, Leicestershire, UK, in two seasons using a range of plant densities in conjunction with shading materials to manipulate PAR and R : FR independently. The spread of the root plate, which has been linked most strongly with anchorage strength, was almost exclusively influenced by PAR intercepted per plant at the beginning of stem extension. Root number and root length were influenced by both PAR and R : FR. When structural roots (defined as thicker than 0.5 mm) and nonstructural roots were considered separately, it was discovered that increasing plant density and PAR shading reduced the length of both structural and nonstructural roots. However, reducing R : FR only reduced the length of structural roots without affecting the length of nonstructural roots. [source]

Local floral composition and the behaviour of pollinators: attraction to and foraging within experimental patches

ECOLOGICAL ENTOMOLOGY, Issue 5 2010
AMPARO LÁZARO
1. Understanding how foraging decisions take place at the local scale is relevant because they may directly affect the fitness of individual plants. However, little is known about how local diversity and density affect the foraging behaviour of most pollinator groups. 2. By introducing two potted plant species (Salvia farinacae and Tagetes bonanza) into two populations of Taraxacum officinale, we investigated how plant identity, the mixtures of these plant species, and total plant density affected the attraction to and the foraging within a patch for six pollinator groups. 3. The foraging behaviour was mainly driven by the availability of the preferred plant species, and secondly by patch diversity and density. In general, dense patches and those containing the three-species mixture were preferred by all insect groups for arrival, although muscoid and hover flies responded less to local floral composition than bees. Local diversity and density had, however, a weaker effect on foraging behaviour within patches. Site dependence in response to floral treatments could be attributable to differences between sites in pollinator assemblage and Taraxacum density. 4. Studies like ours will help to understand how foraging decisions occur at the local scale and how foraging patterns may differ between pollinators and sites. [source]

Colonisation of pitcher plant leaves at several spatial scales

ECOLOGICAL ENTOMOLOGY, Issue 4 2003
M. Kurtis Trzcinski
Abstract., 1.,The effect of meso-scale (zone within bog and local plant density) and fine-scale (leaf length and resource availability) factors on the colonisation of pitcher plant leaves by arthropods was examined in an eastern Canadian bog. 2.,In spring, the abundances of three arthropods, the mosquito Wyeomyia smithii, the midge Metriocnemus knabi, and the mite Sarraceniopus gibsoni, were determined for plots with low, moderate, and high densities of pitcher plants. All overwintering inhabitants were then removed from the plots. Newly opening leaves were colonised from outside the plots, and arthropod abundances were assessed again in autumn. 3.,Pitcher plant fauna varied in their response to the meso-scale factors. In autumn (soon after colonisation), midges were more abundant in areas with high densities of pitcher plants. The relationship between mosquito abundance and plant density, and the variation in abundance among zones within the bog in the spring, were probably due to overwintering mortality. 4.,All taxa responded to the fine-scale factors, leaf length, and capture rate, in the autumn, but the strength of the responses frequently depended on a meso-scale factor (plant density), in which responses were usually strongest where plants were sparse. Thus, the interaction between meso- and fine-scale processes needs to be considered when interpreting patterns of species abundance within arthropod assemblages in pitcher plant leaves. [source]

Linseed (Linum usitatissimum L.) Cultivars and Breeding Lines as Stem Biomass Producers

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2000
H. S. Sankari
Linseed (Linum usitatissimum L.) stems, which contain bast fibres, make up a considerable part of the linseed biomass, but are considered a by-product of no value. The feasibility of cultivating existing linseed cultivars and breeding lines for dual-purpose use of stem and seed was studied in 1995,97 in Jokioinen, Finland. Finnish linseed cv. Helmi was compared with 10 linseed genotypes and one flax cultivar for stem yield, ratio of stem yield to seed yield, and plant stand height and density. The stem yield of cv. Helmi averaged 1317 kg dry matter ha -1. Significantly higher stem yields were produced by breeding lines Bor 15 and Bor 18 and cvs Gold Merchant, Norlin and Martta. The cv. Helmi produced lower stem yield than seed yield while breeding lines Bor 15 and Bor 18 and cvs Gold Merchant and Martta yielded more stem than seeds. The difference in the ratio of stem yield to seed yield between them and cv. Helmi was statistically significant. The mean plant stand height was 60.3 cm and the final plant density 594 plants m -2. No relationship was found between stem yield and height or density. Within 2 days of seed threshing, stems of early maturing Finnish genotypes dried up in the field to nearly 15 % moisture content, even in the middle of September (1996). The early maturing breeding lines Bor 15 and Bor 18, with their significantly higher stem yields relative to cv. Helmi, are recommended for dual-purpose use. Zusammenfassung Der bastfasernenthaltende Stengel des Ölleins (Linum usitatissimum L.) bildet einen Grossteil der oberirdischen Biomasse von Öllein, der häufig keiner Nutzung zugeführt wird. Um das Potential bestehender Ölleinsorten und -zuchtlinien für eine Doppelnutzung von Samen und Stengelbiomasse zu überprüfen, wurden in den Jahren 1995,97 in Jokioinen (Finland) Feldversuche durchgeführt. Die finnische Ölleinsorte Helmi wurde mit zehn Ölleinzuchtstämmen und einer Faserleinsorte angebaut, und der Stengelertrag, der Stengelertrag im Verhältnis zum Samenertrag und die Bestandeshöhe und -dichte wurden ermittelt. Der Stengelertrag betrug bei Helmi durchschnittlich 1317 kg Trockenmasse ha -1. Signifikant höhere Stengelerträge wurden von den Zuchtlinien Bor 15 und Bor 18, den Sorten Gold Merchant, Norlin und Martta produziert. Helmi produzierte im Mittel einen geringeren Stengel , als Samenertrag. Die Stengelerträge der Zuchtstämme Bor 15 und Bor 18 und der Sorten Gold Merchant und Martta waren höher als die Samenerträge. Zwischen diesen Genotypen und der Sorte Helmi ist der Unterschied des Ertragsverhältnisses signifikant. Die Bestandeshöhe lag im Durchschnitt bei 60,3 cm und die Bestandesdichte betrug im Mittel 594 Pflanzen m -2. Eine Korrelation zwischen dem Stengelertrag und der Bestandeshöhe bzw. -dichte konnte nicht nachgewiesen werden. Die Stengel der frühen finnischen Genotypen trockneten nach dem Dreschen auf dem Feld (Mitte September 1996) in zwei Tagen auf einen Feuchtegehalt von 15% ab. Die frühreifen Zuchtlinien Bor 15 und Bor 18 können aufgrund ihrer signifikant höheren Stengelerträge im Vergleich zu der Sorte Helmi für eine Doppelnutzung empfohlen werden. [source]

Impact of the black rhinoceros (Diceros bicornis minor) on a local population of Euphorbia bothae in the Great Fish River Reserve, South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009
Bodina L. Luske
Abstract In the Great Fish River Reserve, South Africa, black rhinoceros (Diceros bicornis minor) feed extensively on a local population of Euphorbia bothae. Maintaining the endangered black rhinoceros and the protected E. bothae population are both conservation priorities of the reserve. Therefore, the sustainability of this plant,animal interaction was investigated by comparing population characteristics, browsing incidence and intensity within the reserve and in an adjacent exclosure without access to rhino. Fixed-point photographs showed that over a 2-month period 36.6% of 213 monitored plants were browsed, with an average biomass loss of 13%, and 1% were destroyed. Of 26 plants re-photographed after approximately 3 years, 70% showed a decrease in biomass, averaging 37.8% over this period. In this time span, 19% of the monitored plants died. Small plants (<45 cm) were over-represented in the rhino-browsed area, whereas the fraction of reproductively active plants and overall plant density were found to be lower than in the adjacent exclosure. No evidence of short-term compensatory growth in response to browsing was found for E. bothae. This study indicates that, with the current population size, rhinos are overexploiting the E. bothae population and special measures should be taken to prevent local extinction. Résumé Dans la Great Fish River Reserve, en Afrique du Sud, le rhinocéros noir (Diceros bicornis minor) se nourrit en très grande partie d'une population locale d'Euphorbia bothae. Le maintien du rhino noir en danger et de la population protégée d'E. bothae sont deux priorités de la réserve en matière de conservation. C'est pourquoi on a investigué la durabilité de cette interaction plante-animal en comparant les caractéristiques des populations, l'incidence et l'intensité de la consommation du rhino dans la réserve et dans un enclos adjacent d'où les rhinos sont exclus. Des photographies prises d'un point fixe ont montré que, sur une période de deux mois, 36.6% des 213 plantes suivies avaient été broutées, avec une perte moyenne de biomasse de 13%, et un pour cent avait été détruit. Des 26 plantes qui avaient été rephotographiées après environ trois ans, 70% montraient une diminution de la biomasse, qui était de 37.8% en moyenne pour cette période. Pendant ce laps de temps, 19% des plantes suivies sont mortes. Les petites plantes (<45 cm) étaient surreprésentées dans la zone broutée par les rhinos, alors que la fraction des plantes actives au point de vue reproduction et la densité générale des plantes se sont avérées plus faibles que dans l'enclos adjacent. On n'a pu mettre en évidence aucune croissance compensatoire d'E. bothaeà court terme en réponse au broutage des rhinos. Cette étude indique que, vu la taille actuelle de leur population, les rhinos surexploitent la population d'E. bothae et qu'il faut prendre des mesures spéciales pour empêcher l'extinction locale de cette dernière. [source]

Status of the Mara Woodlands in Kenya

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2004
Matthew J. Walpole
Abstract The woodlands of the Masai Mara National Reserve in Kenya have suffered dramatic declines over four decades as a result of elephant and fire pressure. This study examined the current status of woody resources in the Reserve and browse pressure thereon, using both classification (TWINSPAN) and ordination (DCA) techniques. From 333 widespread regular plots used to survey the vegetation, a total of 62 woody species were identified. Thirteen woody habitats were identified on the basis of species composition, varying from species-rich closed thickets and forest to less diverse open grasslands. A NW/SE stratification of the more open habitats was observed, possibly as a result of differences in soils, rainfall and drainage. Both plant density and diversity were lower than in communal and privately managed areas outside the Reserve. Moreover, browser pressure was substantially higher than that observed previously in the ecosystem, and suggests increased competition for scarcer woody resources within the Reserve. This has implications for the management of the ecosystem as a whole. As woodland and thickets continue to decline, long-term monitoring should expand to encompass the wider habitat diversity of the open grasslands and unprotected areas where much of the regeneration potential resides. Résumé Les forêts de la Réserve Nationale de Masai Mara, au Kenya, ont subi des réductions dramatiques depuis quatre décennies, suite à la pression des éléphants et des feux. Cette étude a examiné le statut actuel des ressources en bois dans la Réserve et la pression du pâturage qui s'y ajoute, en utilisant les techniques de classification (TWINSPAN) et d'ordination (DCA). Dans 333 plots régulièrement dispersés, utilisés pour étudier la végétation, on a identifié 62 espèces ligneuses. On a identifié aussi 13 habitats forestiers sur la base de la composition des espèces, depuis les buissons et les forêts fermés riches en espèces jusqu'aux prairies ouvertes moins diverses. On a observé une stratification NO/SE dans les habitats plus ouverts, résultat peut-être de différences de sols, de chutes de pluies et de drainage. La densité et la diversité des plantes étaient plus faibles que dans les aires gérées en commun ou de façon privée en dehors de la Réserve. Qui plus est, la pression des animaux qui mangent les buissons y était substantiellement plus élevée que celle qu'on observait jadis dans cet écosystème, et elle laisse penser qu'il y a une compétition plus forte pour des ressources ligneuses plus rares dans la Réserve. Ceci a des implications pour la gestion de l'écosystème dans son ensemble. Si les forêts et les buissons continuent à se rèduire, le monitoring à long terme devrait s'élargir pour englober la plus grande diversité d,habitat des prairies ouvertes et des aires non protégées où réside l'essentiel du potentiel de régénération. [source]

Trends in woody vegetation cover in the Kruger National Park, South Africa, between 1940 and 1998

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2000
H. C. Eckhardt
Changes in the cover and density of shrubs and trees were assessed from aerial photographs (1940, 1974 and 1998) as well as from fixed-point photographs taken in 1984 and 1996 in the Kruger National Park, South Africa. Woody cover (trees and shrubs combined) increased by 12% on granite substrates but decreased by 64% on basalt substrates over the past 58 years. Both these figures are expressed in terms of the initial values, respectively. The density of the large tree component of woody vegetation decreased on both substrates. Woody vegetation cover declined as fire return periods became shorter, but the relationship was weak. The increases in woody plant density and cover on granite are thought to be the result of decreased competition from grasses, which in turn is a result of overgrazing by wild herbivores whose numbers have been kept high through the provision of surface water. These effects were not seen on the relatively nutrient-rich basalts, where grasses can recover rapidly even after heavy grazing. The decline in overall woody cover on basalts is interpreted as a result of regular, short-interval prescribed burning over the past 40 years, while the universal decline in large trees seems to result from an interaction between regular, frequent fires and utilization by elephants. The implications for management are discussed. Résuné On a évalué les changements du couvert et de la densité des arbustes et des arbres à partir de photos aériennes (1940, 1974 et 1998) et de photos prises d'un endroit fixe en 1984 et en 1996 dans le Parc National Kruger, en Afrique du Sud. Le couvert boisé (arbustes et arbres pris ensemble) a augmenté de 12% sur les substrats granitiques mais diminué de 64% sur les substrats basaltiques, au cours des 58 dernières années. Ces deux chiffres sont exprimés en termes de valeurs initiales, respectivement. La densité de la composante de grands arbres de la végétation boisée a diminué sur les deux substrats. Le couvert végétal boisé a diminué alors que les périodes de récupération entre les feux raccourcissaient, mais la relation est faible. On pense que l'augmentation de la densité et du couvert boisés sur le granite est le résultat d'une diminution de la compétition exercée par les herbes qui elle, résulte d'un surpâturage des herbivores sauvages dont le nombre a été maintenu élevé par l'apport d'eau de surface. On n'a pas observé ces effets sur les basaltes relativement riches en nutriments, car les herbes peuvent y repousser rapidement même après un pâturage intense. On interprète le déclin du couvert boisé global sur le basalte comme le résultat des feux provoqués régulièrement et avec de brefs intervalles depuis 40 ans, alors que le déclin général des grands arbres semble être le résultat d'une interaction entre les feux, réguliers et fréquents, et la présence des éléphants. On discute de ce que cela implique pour la gestion. [source]

Do linear landscape elements in farmland act as biological corridors for pollen dispersal?

JOURNAL OF ECOLOGY, Issue 1 2010
Anja Van Geert
Summary 1.,Habitat fragmentation in agricultural landscapes has reduced the population sizes of many plant species while increasing their spatial isolation. Restoration or maintenance of the connectivity by gene flow between the fragmented patches may be determinant to sustaining viable populations, especially for insect-pollinated species. Functional biological corridors facilitating pollen flow between remnants in a human-dominated matrix might achieve this. 2.,Dye dispersal was investigated for the extremely fragmented insect-pollinated herb Primula vulgaris, using fluorescent dye particles as pollen analogues, in a study site comprising 20 populations, of which 13 pairs were physically connected by a linear landscape elements (LLEs, ditches), and 11 pairs were not connected by an LLE. The dye deposition events were used to fit a model of pollen dispersal at the landscape level. We examined whether existing LLEs in the intensively used agricultural landscape act as functional corridors for pollen dispersal. The effects of LLE length and size and plant density of the recipient population on the dispersal patterns were tested. 3.,Dye dispersal showed a leptokurtic decay distribution, with 80% of the dye transfers occurring at less than 85.1 m, and a maximal distance of 1010.8 m. The mean distance travelled by fluorescent dye particles based on the dye dispersal model was , = 87 m. 4.,Dye dispersal between populations was found to be significantly higher when populations were connected by an LLE, than when populations were unconnected. For the group of population pairs connected by an LLE, dye deposition significantly decreased with the distance to dye source, but was not related to recipient population size and plant density. 5.,Synthesis. Our study is, to our knowledge, the first to demonstrate that existing LLEs in an intensively used farmland may act as functional biological corridors facilitating pollen dispersal through pollinator movements. The maintenance or restoration of a network of populations connected by LLEs, but also by other landscape structures (e.g. population relays in vegetation patches and networks of small elements allowing indirect connections) should be strongly encouraged. [source]

Desert shrubs have negative or neutral effects on annuals at two levels of water availability in arid lands of South Australia

JOURNAL OF ECOLOGY, Issue 6 2008
James T. Weedon
Abstract 1Perennial plants have been shown to facilitate understorey annual plant species in arid lands through the modification of spatial patterns of resources and conditions. This effect can result from a balance between simultaneously positive and negative interactions, both direct and indirect. This balance may shift with temporal variability in water availability. 2We conducted a field experiment in a chenopod shrubland in South Australia to separate the effects of shade, below-ground competition, and soil modification by shrubs on the performance of annual plants, and to determine if the strength and direction of the interaction shifted with changes in water availability. 3Annual plant diversity and seedling density was highest in plots established in open sites away from the dominant shrubs (Maireana sedifolia). Experimental removal of M. sedifolia increased seedling density compared to plots under undisturbed shrubs and plots where the removed shrub was replaced with artificial shade. Shading of open plots also reduced seedling density. Annual plant biomass was highest in areas where shrubs had been removed and was reduced by artificial shading. Biomass was higher in open plots than under intact shrubs. Experimental water addition did not alter plant density, but increased biomass across all treatments, particularly in artificially shaded bush plots. 4Synthesis. Our results show that the overall effect of shrubs on the annual plant community in the system is negative under the range of water availabilities experienced during the experiment. This negative net-effect results from a combination of simultaneous facilitation via soil modification, and above- and below-ground competition. Assessment in different systems of different combinations of mechanisms that have simultaneously positive and negative effects will allow us to refine hypotheses seeking to explain the relative importance of facilitation across spatial and temporal gradients. [source]

Rainfall effects on rare annual plants

JOURNAL OF ECOLOGY, Issue 4 2008
Jonathan M. Levine
Summary 1Variation in climate is predicted to increase over much of the planet this century. Forecasting species persistence with climate change thus requires understanding of how populations respond to climate variability, and the mechanisms underlying this response. Variable rainfall is well known to drive fluctuations in annual plant populations, yet the degree to which population response is driven by between-year variation in germination cueing, water limitation or competitive suppression is poorly understood. 2We used demographic monitoring and population models to examine how three seed banking, rare annual plants of the California Channel Islands respond to natural variation in precipitation and their competitive environments. Island plants are particularly threatened by climate change because their current ranges are unlikely to overlap regions that are climatically favourable in the future. 3Species showed 9 to 100-fold between-year variation in plant density over the 5,12 years of censusing, including a severe drought and a wet El Niño year. During the drought, population sizes were low for all species. However, even in non-drought years, population sizes and per capita growth rates showed considerable temporal variation, variation that was uncorrelated with total rainfall. These population fluctuations were instead correlated with the temperature after the first major storm event of the season, a germination cue for annual plants. 4Temporal variation in the density of the focal species was uncorrelated with the total vegetative cover in the surrounding community, suggesting that variation in competitive environments does not strongly determine population fluctuations. At the same time, the uncorrelated responses of the focal species and their competitors to environmental variation may favour persistence via the storage effect. 5Population growth rate analyses suggested differential endangerment of the focal annuals. Elasticity analyses and life table response experiments indicated that variation in germination has the same potential as the seeds produced per germinant to drive variation in population growth rates, but only the former was clearly related to rainfall. 6Synthesis. Our work suggests that future changes in the timing and temperatures associated with the first major rains, acting through germination, may more strongly affect population persistence than changes in season-long rainfall. [source]

Seed limitation in a Panamanian forest

JOURNAL OF ECOLOGY, Issue 5 2005
JENS-CHRISTIAN SVENNING
Summary 1The role of seed limitation in tropical forests remains uncertain owing to the scarcity of experimental evidence. We performed seed addition experiments to assess seed limitation for 32 shade-tolerant tropical forest species and monitored the natural seed rain of 25 of these species for 17 years. 2One, two or five seeds were sown into 0.0079-m2 plots for large- (n = 5 species), medium- (n = 5) and small-seeded species (n = 22), respectively. The experiment was replicated at 69 sites, placed in groups of three at 23 locations. Seedling establishment was evaluated after 1 and 2 years in paired seed addition and control plots. Natural seedling emergence and understorey plant density were also measured. 3Median natural seed rain was 0.31 seeds m,2 year,1 per focal species. 4Seed addition enhanced seedling establishment in 31 and 26 of the 32 species after 1 and 2 years, respectively. Mean number of focal species' seedlings after 2 years was 0.002 seedlings in control plots and 0.12, 0.37 and 0.60 seedlings in seed addition plots for large-, medium- and small-seeded species, respectively. 5A 25 seeds added treatment increased seedling establishment by , 2.0-fold over the five seeds added treatment after 2 years. 6Community-wide recruitment and understorey plant density were strongly seed-limited. The natural density of understorey plants averaged 12 plants m,2 and was significantly less than for seedlings of the single focal species in plots with , 2 seeds added 2 years earlier. 7The number of established seedlings per seed added was independent of seed size. 8Treatment (adding zero or five seeds), species identity and location all affected seedling establishment for the 11 small-seeded species represented at all sites, with treatment and its interactions accounting for 86% of the explained variation. 9Our results suggest that seed limitation plays a dominant role in seedling recruitment and understorey plant community assembly in tropical forests. Although strong seed limitation may set the stage for species-neutral community assembly, the species differences in seedling establishment rate and its spatial variation demonstrate an important role for species-specific processes. [source]

Reduced reproductive success in small populations of the self-incompatible Primula vulgaris

JOURNAL OF ECOLOGY, Issue 1 2004
Rein Brys
Summary 1Habitat fragmentation and the resulting decline in population size can affect biotic interactions and reproductive success of plant species. We investigated the impact of habitat type, population size, morph type and frequency, plant density, floral display and predation on different reproductive components in 16 populations of the distylous self-incompatible perennial herb, Primula vulgaris , a rare, declining species in Belgium. 2Although habitat type accounted for significant variation in population size, we did not find any relation between habitat type and either reproductive and vegetative characteristics. Population size, however, strongly affected reproductive success, such that plants in small populations produced significantly fewer fruits per plant and seeds per fruit, and therefore fewer seeds per plant. 3No significant difference was found between morph types for any reproductive characteristic, nor an interaction with population size. However, when morph frequency was strongly biased (, 1 : 3), the proportion of flowers setting fruit and the number of seeds per fruit were significantly lower in individuals of the common morph type. 4Within populations, individual plants varied tremendously in size and floral display. Total number of fruits per plant significantly increased with floral display, but the highest fruit set per flower was found at intermediate flower number. 5The proportion of fruit suffering pre-dispersal predation per plant significantly increased with floral display, but this did not offset the potential fitness gains of producing a large display. Furthermore, the absolute number of predated fruits per plant was significantly and positively affected by the interaction of the total number of fruits per plant and the density of the population. [source]

The influence of nutrient loading, dissolved inorganic carbon and higher trophic levels on the interaction between submerged plants and periphyton

JOURNAL OF ECOLOGY, Issue 1 2002
J. Iwan Jones
Summary 1We studied the growth of a submerged aquatic plant in relation to periphytic and planktonic algae over a range of nutrient and dissolved inorganic carbon (DIC) availabilities. 2In consecutive years two factorial experiments were conducted in 48 artificial ponds (each 3.14 m3), comprising four concentrations of DIC (1.5, 2.5, 3.5 or 4.5 mm) each crossed with three separate nutrient loadings (10 µg L,1 P and 0.2 mg L N, 50 µg L,1 P and 1 mg L N, or 200 µg L,1 P and 4 mg L N). The second experiment differed by the inclusion of fish in the ponds. 3In the first year DIC had no effect on plant growth, but nutrient loading did. Plants failed to grow in treatments where phytoplankton density was high (> 100 µg L,1). Where phytoplankton was low, high numbers of invertebrates colonized the ponds, and periphyton abundance on the plants was low. In the second year, where phytoplankton never achieved the densities of the previous year, there was a significant effect of DIC concentration on plant growth but not of nutrients. Invertebrate abundance was lower and periphyton on the plants correspondingly higher. 4In both years increased nutrient loading had no effect on the abundance of periphyton growing on the surface of the plants. Periphyton abundance was determined by the density of grazing invertebrates in the ponds. 5There was a negative relationship between periphyton density and final plant density, which became significantly less steep with increasing DIC, indicating that periphyton and plants were competing for carbon. 6DIC concentration has the potential to influence community structure in shallow lakes, altering competitive interactions between periphyton and plants and rendering low DIC lakes more prone to loss of plants when nutrient loading increases. However, the expression of this competition between periphyton and plants will depend on the density of grazing invertebrates present, which is itself influenced by the intensity of fish predation on those invertebrates. [source]

Yield of Illicit Indoor Cannabis Cultivation in The Netherlands

JOURNAL OF FORENSIC SCIENCES, Issue 5 2006
Marcel Toonen Ph.D.
ABSTRACT: To obtain a reliable estimation on the yield of illicit indoor cannabis cultivation in The Netherlands, cannabis plants confiscated by the police were used to determine the yield of dried female flower buds. The developmental stage of flower buds of the seized plants was described on a scale from 1 to 10 where the value of 10 indicates a fully developed flower bud ready for harvesting. Using eight additional characteristics describing the grow room and cultivation parameters, regression analysis with subset selection was carried out to develop two models for the yield of indoor cannabis cultivation. The median Dutch illicit grow room consists of 259 cannabis plants, has a plant density of 15 plants/m2, and 510 W of growth lamps per m2. For the median Dutch grow room, the predicted yield of female flower buds at the harvestable developmental stage (stage 10) was 33.7 g/plant or 505 g/m2. [source]

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2008
Yun-Zhou Qiao
Abstract Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient + 350 (± 25) ,mol/mol) under two planting densities (28 or 84 plants/m2) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same. [source]

Water-Yield Reduction After Afforestation and Related Processes in the Semiarid Liupan Mountains, Northwest China,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2008
Yanhui Wang
Abstract:, The increase of coverage of forest/vegetation is imperative to improve the environment in dry-land areas of China, especially for protecting soil against serious erosion and sandstorms. However, inherent severe water shortages, drought stresses, and increasing water use competition greatly restrict the reforestation. Notably, the water-yield reduction after afforestation generates intense debate about the correct approach to afforestation and forest management in dry-land areas. However, most studies on water-yield reduction of forests have been at catchment scales, and there are few studies of the response of total evapotranspiration (ET) and its partitioning to vegetation structure change. This motivates us to learn the linkage between hydrological processes and vegetation structure in slope ecosystems. Therefore, an ecohydrological study was carried out by measuring the individual items of water balance on sloping plots covered by different vegetation types in the semiarid Liupan Mountains of northwest China. The ratio of precipitation consumed as ET was about 60% for grassland, 93% for shrubs, and >95% for forestland. Thus, the water yield was very low, site-specific, and sensitive to vegetation change. Conversion of grassland to forest decreased the annual water yield from slope by 50-100 mm. In certain periods, the plantations at lower slopes even consumed the runon from upper slopes. Reducing the density of forests and shrubs by thinning was not an efficient approach to minimize water use. Leaf area index was a better indicator than plant density to relate ET to vegetation structure and to evaluate the soil water carrying capacity for vegetation (i.e., the maximum amount of vegetation that can be supported by the available soil water for an extended time). Selecting proper vegetation types and plant species, based on site soil water condition, may be more effective than the forest density regulation to minimize water-yield reduction by vegetation coverage increase and notably by reforestation. Finally, the focuses in future research to improve the forest-water relations in dry-land areas are recommended as follows: vegetation growth dynamics driven by environment especially water conditions, coupling of ecological and hydrological processes, further development of distributed ecohydrological models, quantitative relation of eco-water quota of ecosystems with vegetation structures, multi-scaled evaluation of soil water carrying capacity for vegetation, and the development of widely applicable decision support tools. [source]

What determines emergence and net recruitment in an early succession plant community?

JOURNAL OF VEGETATION SCIENCE, Issue 4 2008
Disentangling biotic, abiotic effects
Abstract Question: How do different regeneration scenarios shape species composition at two stages of plant community establishment (emergence and net recruitment) in an early succession? Location: Northern Spain. Methods: In a recently ploughed field, we created eight regeneration scenarios with light, water and nitrogen availability (five replicates each). Seedlings of all species were monitored from emergence to death during one year. Abiotic and biotic variables were measured per quadrat, i.e. soil texture, nutrient contents, seed bank densities and composition, neighbour plant species densitiy and cover. We used partial ordination methods in order to separate the effect of each environmental variable on species composition during emergence and adult net recruitment. Results: Light treatment determined annual plant density at time of emergence and recruitment, while water addition controlled the recruitment of perennials. Resource levels explained the emerged species composition; this effect was not translated into the recruited species composition. N-addition and N + water addition were strongly associated to species abundances at the time of emergence. Seedling composition in summer was correlated with seed abundance of Cerastium spp. Neighbour species density and cover (mainly Arrhenatherum bulbosum, Agropyron repens and Picris echioides) explained significant fractions of species composition in the emergence and recruitment of the different cohorts. Interactions between species seem to vary in intensity among cohorts and in the key plant species that determined species abundance along succession. Conclusions: Our scenarios exerted contrasting and multilevel effects on the development of our early succession community. Resource availability differently affected plant density and species composition at different life stages. It is relevant to consider different life stages in plant community studies. However, regeneration conditions and other abiotic factors are not enough to explain how community composition varies. [source]

Sample size and the detection of a hump-shaped relationship between biomass and species richness in Mediterranean wetlands

JOURNAL OF VEGETATION SCIENCE, Issue 2 2006
J.L. Espinar
Abstract Questions: What is the observed relationship between biomass and species richness across both spatial and temporal scales in communities of submerged annual macrophytes? Does the number of plots sampled affect detection of hump-shaped pattern? Location: Doñana National Park, southwestern Spain. Methods: A total of 102 plots were sampled during four hydrological cycles. In each hydrological cycle, the plots were distributed randomly along an environmental flooding gradient in three contrasted microhabitats located in the transition zone just below the upper marsh. In each plot (0.5 m × 0.5 m), plant density and above- and below-ground biomass of submerged vegetation were measured. The hump-shaped model was tested by using a generalized linear model (GLM). A bootstrap procedure was used to test the effect of the number of plots on the ability to detect hump-shaped patterns. Result: The area exhibited low species density with a range of 1,9 species and low values of biomass with a range of 0.2 -87.6 g-DW/0.25 m2. When data from all years and all microhabitats were combined, the relationships between biomass and species richness showed a hump-shaped pattern. The number of plots was large enough to allow detection of the hump-shaped pattern across microhabitats but it was too small to confirm the hump-shaped pattern within each individual microhabitat. Conclusion: This study provides evidence of hump-shaped patterns across microhabitats when GLM analysis is used. In communities of submerged annual macrophytes in Mediterranean wetlands, the highest species density occurs in intermediate values of biomass. The bootstrap procedure indicates that the number of plots affects the detection of hump-shaped patterns. [source]

Density-Induced Plant Size Reduction and Size Inequalities in Ethylene-Sensing and Ethylene-Insensitive Tobacco

The Influence of Historical Land Use and Water Availability on Grassland Restoration

RESTORATION ECOLOGY, Issue 2010
Zhuwen Xu
The ecological role of historical land use has rarely been explored in the context of grassland restoration. We conducted a 4-year field experiment in a steppe and an old field in Inner Mongolia in northern China to examine the influence of historical land use and water availability on ecosystem restoration. Species richness, evenness, and plant cover were higher in the steppe than in the old field. The steppe was more temporally stable compared with the old field in terms of species richness, evenness, plant density, and cover. Water addition increased peak aboveground biomass, belowground net primary productivity, species richness, plant density, and cover in both the steppe and the old field. Water addition also enhanced the stability of ecosystems and the restoration of grassland. Our findings suggested that historical land use determines community structure and influences the process of grassland restoration. Converting grasslands to farmland in semiarid areas can cause the long-term loss of biodiversity and instability of ecosystem with consequent impacts on ecosystem services. The amendment of limited resources is an effective practice to increase the success of ecosystem restoration. [source]

Estuarine Restoration of Submersed Aquatic Vegetation: The Nursery Bed Effect

RESTORATION ECOLOGY, Issue 4 2010
Angela Hengst
The historic decline of submersed aquatic vegetation (SAV) in mesohaline regions of Chesapeake Bay, United States involved a diversity of plant species. The recent modest recovery is mostly, however, associated with a single, prolific but ephemeral species, Ruppia maritima. Two previously abundant and more stable species, Potamogeton perfoliatus and Stuckenia pectinata, have shown virtually no evidence of recovery. Based on previous studies that demonstrated the ability of R. maritima stands to enhance water clarity and nutrient conditions for SAV growth, we hypothesized that these beds would serve as effective "nursery" areas to incite transplant success for other SAV. We conducted experiments in a two-phase study at small and large spatial scales designed to explore this "nursery effect" as a restoration approach to increase plant species diversity. The first phase was conducted at small spatial scales to test effects of patch density by planting P. perfoliatus and S. pectinata into bare, sparse, and densely vegetated areas within three similar R. maritima beds in a tributary of Chesapeake Bay. Mean seasonal percent survivorship and shoot density were significantly higher in bare patches compared to vegetated patches. In the second phase of the study, P. perfoliatus was transplanted into separate R. maritima beds of different densities to test the effect of bed scale plant density on P. perfoliatus survival and growth. Transplant success of P. perfoliatus was positively correlated with the density of R. maritima among all sites. [source]

Seedling Establishment and Survival on Restored Campsites in Subalpine Forest

RESTORATION ECOLOGY, Issue 3 2007
David N. Cole
Abstract This study experimented with common restoration techniques (scarification, soil amendments, mulch, and seeding) on six closed wilderness campsites in subalpine forests in Oregon. Effectiveness in encouraging seedling establishment, growth, and survival was assessed every year for the first 7 years following treatment. Closure and restoration of the campsites increased the density of plants established from seed. Despite an original density of virtually zero, mean density of perennial plants was 55 plants/m2 7 years after closure. All the treatments, with the exception of the biodegradable mulch mat, increased plant density. Seven years after treatment, seeding had increased plant density 5-fold, whereas scarification and soil amendments (organic matter, compost, and soil inoculum) had each increased density 3-fold. The organic and compost amendments also had the positive benefit of increasing growth rates and shortening the time-to-reproductive maturity. Results suggest that restoration of the herbaceous cover on these campsites can occur rapidly using the techniques employed. All but one of the species we seeded established in substantial quantities and survived at densities exceeding their density in the naturally sparse herbaceous cover on these sites. Thirty-six perennial species volunteered on these sites. The remaining challenge is reestablishment of the shrub species that comprise much of the ground cover in these forests. These species seldom establish from seed. [source]