Effects of dispersal, shrubs, and density-dependent mortality on seed and seedling distributions in temperate forests

Processes limiting recruitment of trees may have large impacts on forest dynamics. In this paper, we deter- mined the effects of dispersal, shrubs (Rhododendron maximum), and density-dependent mortality on seed and seedling distributions of Southern Appalachian trees. We quantified the spatial distribution of seed rain, seed bank densities, first-year seedlings, and older than first-year seedlings in five vegetation plots. We fit models to these data assuming effects of limited dispersal, R. maximum (an understory shrub), and (or) density-dependent mortality (as well as a null model with none of these effects) and used best-fitting models to indicate which processes affected a particular species. We found that all factors examined limit species distributions, and thus, affect seedling dynamics. Seedling densities are higher near parent trees long after dispersal occurs. This pattern is less frequently observed for animal-dispersed species than for wind-dispersed species, presumably due to secondary dispersal of seeds by animals. Seedling densities of five species are decreased beneath R. maximum. Shade tolerance does not explain which species are affected, sug- gesting that factors other than low light are responsible for increased seedling mortality under this shrub. Our results suggest that density-dependent mortality affects four species, decreasing seedling densities close to parent trees. Dis- persal, density-dependent mortality, and R. maximum all act in ways that may promote or limit diversity, illustrating that multiple factors are likely to control species diversity.

[1]  Michael Lavine,et al.  IMPLICATIONS OF SEED BANKING FOR RECRUITMENT OF SOUTHERN APPALACHIAN WOODY SPECIES , 2005 .

[2]  C. Lafon.  Stand dynamics of a yellow-poplar (Liriodendron tulipifera L.) forest in the Appalachian mountains, Virginia, USA , 2004 .

[3]  N. Manokaran,et al.  Tree distribution pattern and fate of juveniles in a lowland tropical rain forest – implications for regeneration and maintenance of species diversity , 1997, Plant Ecology.

[4]  O. Eriksson,et al.  Seed and microsite limitation of recruitment in plant populations , 1992, Oecologia.

[5]  W. C. Johnson,et al.  Estimating dispersibility of Acer, Fraxinus and Tilia in fragmented landscapes from patterns of seedling establishment , 1988, Landscape Ecology.

[6]  S. Ellner,et al.  Coexistence of plant species with similar niches , 1984, Vegetatio.

[7]  B. Beckage,et al.  SEEDLING SURVIVAL AND GROWTH OF THREE FOREST TREE SPECIES: THE ROLE OF SPATIAL HETEROGENEITY , 2003 .

[8]  B. Beckage,et al.  Density-dependent mortality and the latitudinal gradient in species diversity , 2002, Nature.

[9]  J. Plotkin,et al.  Species-area curves, spatial aggregation, and habitat specialization in tropical forests. , 2000, Journal of theoretical biology.

[10]  B. Clinton,et al.  A long-term study of tree seedling recruitment in southern Appalachian forests: the effects of canopy gaps and shrub understories , 2000 .

[11]  Kyle E. Harms,et al.  Pervasive density-dependent recruitment enhances seedling diversity in a tropical forest , 2000, Nature.

[12]  A. Packer,et al.  Soil pathogens and spatial patterns of seedling mortality in a temperate tree , 2000, Nature.

[13]  T. T.,et al.  Relations between density of rhododendron thickets and diversity of riparian forests , 2000 .

[14]  B. Clinton,et al.  Inhibition of seedling survival under Rhododendron maximum (Ericaceae): could allelopathy be a cause? , 1999, American journal of botany.

[15]  Campbell O. Webb,et al.  SEEDLING DENSITY DEPENDENCE PROMOTES COEXISTENCE OF BORNEAN RAIN FOREST TREES , 1999 .

[16]  Janneke HilleRisLambers,et al.  Seed Dispersal Near and Far: Patterns Across Temperate and Tropical Forests , 1999 .

[17]  F. Bazzaz,et al.  The fern understory as an ecological filter : Growth and survival of canopy-tree seedlings , 1999 .

[18]  F. Bazzaz,et al.  THE FERN UNDERSTORY AS AN ECOLOGICAL FILTER: EMERGENCE AND ESTABLISHMENT OF CANOPY‐TREE SEEDLINGS , 1999 .

[19]  T. Givnish.  On the causes of gradients in tropical tree diversity , 1999 .

[20]  J. Clark,et al.  Interpreting recruitment limitation in forests. , 1999, American journal of botany.

[21]  R. Kobe.  LIGHT GRADIENT PARTITIONING AMONG TROPICAL TREE SPECIES THROUGH DIFFERENTIAL SEEDLING MORTALITY AND GROWTH , 1999 .

[22]  S. Pacala,et al.  Models Suggesting Field Experiments to Test Two Hypotheses Explaining Successional Diversity , 1998, The American Naturalist.

[23]  D. Greene,et al.  Seed mass and early survivorship of tree species in upland clearings and shelterwoods , 1998 .

[24]  R. Sharitz,et al.  Survival and growth of woody plant seedlings in the understorey of floodplain forests in South Carolina , 1998 .

[25]  James S. Clark,et al.  STAGES AND SPATIAL SCALES OF RECRUITMENT LIMITATION IN SOUTHERN APPALACHIAN FORESTS , 1998 .

[26]  F. Bazzaz,et al.  REGENERATION OF THREE SYMPATRIC BIRCH SPECIES ON EXPERIMENTAL HURRICANE BLOWDOWN MICROSITES , 1998 .

[27]  R. Cintra.  A test of the Janzen-Connell model with two common tree species in Amazonian forest , 1997, Journal of Tropical Ecology.

[28]  N. Wada,et al.  Japanese maple (Acer palmatum var. Matsumurae, Aceraceae) recruitment patterns: seeds, seedlings, and saplings in relation to conspecific adult neighbors. , 1997, American journal of botany.

[29]  Koichi Takahashi.  Regeneration and coexistence of two subalpine conifer species in relation to dwarf bamboo in the understorey , 1997 .

[30]  J. A. Barone,et al.  HERBIVORY AND PLANT DEFENSES IN TROPICAL FORESTS , 1996 .

[31]  M. Westoby,et al.  Seedling longevity under deep shade in relation to seed size , 1996 .

[32]  J. Vose,et al.  Effects of Rhododendron maximum L. on , 1996 .

[33]  J. Vose,et al.  Effects of Rhododendron maximum L. on Acer rubrum L. Seedling Establishment , 1996 .

[34]  George C. Hurtt,et al.  The consequences of recruitment limitation: reconciling chance, history and competitive differences between plants , 1995 .

[35]  Yuan Ji,et al.  Fecundity and Dispersal in Plant Populations: Implications for Structure and Diversity , 1995, The American Naturalist.

[36]  T. Masaki,et al.  Evaluating increased fitness through dispersal: A comparative study on tree populations in a temperate forest, Japan , 1995 .

[37]  G. Houle.  Seed dispersal and seedling recruitment: The missing link(s) , 1995 .

[38]  B. Clinton,et al.  Regeneration Patterns in Canopy Gaps of Mixed-oak Forests of the Southern Appalachians: Influences of Topographic Position and Evergreen Understory , 1994 .

[39]  S. Pacala,et al.  SEEDLING RECRUITMENT IN FORESTS: CALIBRATING MODELS TO PREDICT PATTERNS OF TREE SEEDLING DISPERSION' , 1994 .

[40]  M. Westoby,et al.  The role of large seed size in shaded conditions: experimental evidence , 1994 .

[41]  David Tilman,et al.  Limiting Similarity in Mechanistic and Spatial Models of Plant Competition in Heterogeneous Environments , 1994, The American Naturalist.

[42]  P. Dixon,et al.  Woody plant regeneration in four floodplain forests , 1994 .

[43]  D. Tilman.  Competition and Biodiversity in Spatially Structured Habitats , 1994 .

[44]  James A. Young,et al.  Seeds of woody plants in North America , 1993 .

[45]  M. Westoby,et al.  Seedling growth in relation to seed size among species of arid Australia , 1992 .

[46]  S. Pacala,et al.  Herbivores and Plant Diversity , 1992, The American Naturalist.

[47]  F. Bazzaz,et al.  TREE SEEDLING EMERGENCE ON INTERACTIVE TEMPERATURE AND MOISTURE GRADIENTS AND IN PATCHES OF OLD‐FIELD VEGETATION , 1991 .

[48]  D. Tilman.  Constraints and tradeoffs: toward a predictive theory of competition and succession , 1990 .

[49]  P. Harcombe,et al.  Woody seedling dynamics in an east Texas floodplain forest. , 1989 .

[50]  F. P. Day,et al.  Forest Communities and Patterns , 1988 .

[51]  L. Swift,et al.  Climatology and Hydrology , 1988 .

[52]  J. E. Douglass,et al.  History of Coweeta , 1988 .

[53]  Wayne T. Swank,et al.  Introduction and Site Description , 1988 .

[54]  Wayne T. Swank,et al.  Forest Hydrology and Ecology at Coweeta , 1988, Ecological Studies.

[55]  C. Monk,et al.  The ecological importance of Kalmia latifolia and Rhododendron maximum in the deciduous forest of the southern Appalachians , 1985 .

[56]  D. Phillips,et al.  Notes: Effects of Rhododendron (Rhododendron maximum L.) on Regeneration of Southern Appalachian Hardwoods , 1985 .

[57]  C. Augspurger.  Seedling Survival of Tropical Tree Species: Interactions of Dispersal Distance, Light-Gaps, and Pathogens , 1984 .

[58]  D. Clark,et al.  Spacing Dynamics of a Tropical Rain Forest Tree: Evaluation of the Janzen-Connell Model , 1984, The American Naturalist.

[59]  J. P. Grime,et al.  SEASONAL VARIATION IN THE SEED BANKS OF HERBACEOUS SPECIES IN TEN CONTRASTING HABITATS , 1979 .

[60]  P. Grubb.  THE MAINTENANCE OF SPECIES‐RICHNESS IN PLANT COMMUNITIES: THE IMPORTANCE OF THE REGENERATION NICHE , 1977 .

[61]  Christopher C. Smith,et al.  The Optimal Balance between Size and Number of Offspring , 1974, The American Naturalist.

[62]  J. Connell.  On the role of the natural enemies in preventing competitive exclusion in some marine animals and in rain forest trees , 1971 .

[63]  D. Janzen.  Herbivores and the Number of Tree Species in Tropical Forests , 1970, The American Naturalist.

[64]  G. E. Hutchinson,et al.  The Balance of Nature and Human Impact: The paradox of the plankton , 2013 .

[65]  R. E. Shanks,et al.  Natural Replacement of Chestnut by Other Species in the Great Smoky Mountains National Park , 1959 .

[66]  Robert H. Whittaker,et al.  Vegetation of the Great Smoky Mountains , 1956 .