The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Masashi Ohara - One of the best experts on this subject based on the ideXlab platform.
-
Life-history monographs of Japanese plants. 5: Trillium tschonoskii Maxim. (Trilliaceae)
Plant Species Biology, 2006Co-Authors: Masashi Ohara, Shoichi KawanoAbstract:Life-history characteristics and demography of Trillium tschonoskii (Trilliaceae) were studied and are described here. Trillium tschonoskii is the most wide-ranging species among Asiatic Trillium , ranging from southern Sakhalin, the Japanese Islands (excepting Kyushu) to the Korean Peninsula, Taiwan and further to inland China and the Himalayas. The ecological range of T. tschonoskii is broad, extending from lowland forests to montane and further to subalpine mixed forests consisting of conifers and subalpine birch, Betula ermani . This species is a typical polycarpic perennial, similar to all other Japanese Trillium species, and flowers in early to late April in lowland populations and in midJune to early July in subalpine habitats. Trillium tschonoskii typically has three white petals and three sepals, and its pollinators are diverse, for example, flies, beetles and bees such as Scatophagiae (Diptera), Oedemera lucidicollis (Coleoptera) and Andrena sp. (Hymenoptera). Pollen/ovule ratios of T. tschonoskii are approximately 700, thus T. tschonoskii is potentially an inbreeder. Seed outputs per plant are variable, 29–190 (mean 85.0) in 1980, and 28–168 (mean 79.8) in 1984. Seeds with a large soft juicy elaiosome attract ants, which are effective dispersal agents, but nocturnal elaiosome predators, mainly ground beetles, are also very active. Our long-term observations indicate that it takes approximately 10 years to reach a sexually mature stage and the life expectancy of mature plants is assumed to be exceedingly long, extending over 40 years.
-
Molecular Systematics of Trilliaceae I. Phylogenetic Analyses of Trillium Using matK Gene Sequences
Journal of Plant Research, 1999Co-Authors: Shahrokh Kazempour Osaloo, Masashi Ohara, Frederick H. Utech, Shoichi KawanoAbstract:was conducted using 41 Trillium taxa and two out-group taxa (Veratrum maackii and Helonias bullata). A total of 1608 base pairs were analyzed and compared., and then there were 61 variable (36 informative) sites among Trillium species. Fifteen insertion/deletion events (indels) of six or fifteen base pairs were also detected. Phylogenetic analyses of the sequence data revealed that the subgenus Phyllantherum (sessile-flowered species) forms a distinct monophyletic group, whereas the subgenus Trillium (pedicellate-flowered species) does not form a monophyletic group, and is composed of three distinct groups and three basally located species in the tree: (1) the Erectum group, (2) the Grandiflorum group, and (3) the Pusillum group and (4) the three species, including T. govanianum, T. undulatum, and T. rivale. T .rivale appears to be the most basally diverged and a very specialized taxon among the ingroup members. Our matK data indicated that the closest relative of the subgenus Phyllantherum is the Grandiflorum group. The results are concordant with the results of the RFLP analysis of cpDNA and also more or less with those of the cladistic analysis of morphological characters.
-
Variations in the breeding system and the population genetic structure of Trillium kamtschaticum (Liliaceae)
Heredity, 1996Co-Authors: Masashi Ohara, Haruko Takeda, Yoko Ohno, Yoshiya ShimamotoAbstract:Variations in the breeding system and the population genetic structure of Trillium kamtschaticum (Liliaceae)
Erik S. Jules - One of the best experts on this subject based on the ideXlab platform.
-
Assessing the recovery of a long-lived herb following logging: Trillium ovatum across a 424-year chronosequence
Forest Ecology and Management, 2005Co-Authors: Ansgar Kahmen, Erik S. JulesAbstract:We investigated the long-term recovery of Trillium ovatum (Liliaceae) following clear-cut logging by assessing demographic trends across a forest chronosequence that ranged in age from 2 to 424 years. In each of 20 sites across the chronosequence, we used 50 50 m plots to assess the population size, age and stage structure, seed production, and the spatial distribution of seedlings relative to reproductive plants. We found that Trillium populations were significantly reduced in younger sites and a significant positive relationship of population size and stand age, suggesting that population recovery following standreplacement disturbances may take centuries. Slow recovery rates of Trillium can partly be explained by short seed dispersal distances. We found 67% of new Trillium recruits within only one meter of potential parent plants. Despite the general trend of slow recovery, a few recently disturbed populations showed fast population growth. In these cases, high rates of post-disturbance recruitment were related to the number of individuals surviving the disturbance event. We found that local, within-site seed production can most likely mitigate limited dispersal abilities of Trillium. The rate of Trillium recovery following disturbance, therefore, depends on the number of plants that have persisted through the disturbance event and serve as within-site seed sources. Our study suggests that the nature of the stand-replacement disturbance (i.e., magnitude and intensity) may be critical in determining the recovery of understory plants in managed forests. # 2005 Elsevier B.V. All rights reserved.
-
OF MICE AND MEN AND Trillium: CASCADING EFFECTS OF FOREST FRAGMENTATION
Ecological Applications, 2003Co-Authors: David A. Tallmon, Erik S. Jules, Nikki J. Radke, L. Scott MillsAbstract:Cascading ecological effects of anthropogenic habitat fragmentation have been studied primarily in extreme cases (e.g., the isolation of habitat fragments in a novel habitat matrix such as suburban developments, reservoirs, or agricultural fields), with less attention to more subtle and widespread cases, such as habitat fragmentation due to timber harvest. Few studies have used rigorous demographic data to demonstrate the direct and indirect effects of habitat fragmentation. We trapped deer mice (Peromyscus maniculatus) at five sites over two years in southwest Oregon, USA, and used multi-state capture- recapture models to estimate deer mouse survival and movement in clearcuts, forest-frag- ment edges, forest-fragment interiors, and contiguous forests. We also estimated deer mouse densities in fragmented and unfragmented forests and combined deer mouse demographic studies with Trillium (Trillium ovatum) seed predation trials to link deer mouse changes to reduced Trillium recruitment previously observed at the same study sites. Mouse survival was highest in clearcuts, intermediate in forest fragments, and lowest in unfragmented (control) forests. Mouse movement among clearcuts, forest edges, and forest interiors was common over short time intervals. Collectively, demographic rates led to mouse densities that were 3-4 times higher at forest-fragment sites than at unfragmented sites. Trillium seeds were ;3 times more likely to be depredated in areas of elevated relative mouse abundance than in areas of lower relative abundance. Forest fragmentation has favored mouse populations, resulting in increased seed predation that may decrease recruitment rates and increase local extinction risks for Trillium.
-
OF MICE AND MEN AND Trillium: CASCADING EFFECTS OF
2003Co-Authors: David A. Tallmon, Erik S. Jules, Nikki J. Radke, L. Scott MillsAbstract:Cascading ecological effects of anthropogenic habitat fragmentation have been studied primarily in extreme cases (e.g., the isolation of habitat fragments in a novel habitat matrix such as suburban developments, reservoirs, or agricultural fields), with less attention to more subtle and widespread cases, such as habitat fragmentation due to timber harvest. Few studies have used rigorous demographic data to demonstrate the direct and indirect effects of habitat fragmentation. We trapped deer mice (Peromyscus maniculatus) at five sites over two years in southwest Oregon, USA, and used multi-state capture- recapture models to estimate deer mouse survival and movement in clearcuts, forest-frag- ment edges, forest-fragment interiors, and contiguous forests. We also estimated deer mouse densities in fragmented and unfragmented forests and combined deer mouse demographic studies with Trillium (Trillium ovatum) seed predation trials to link deer mouse changes to reduced Trillium recruitment previously observed at the same study sites. Mouse survival was highest in clearcuts, intermediate in forest fragments, and lowest in unfragmented (control) forests. Mouse movement among clearcuts, forest edges, and forest interiors was common over short time intervals. Collectively, demographic rates led to mouse densities that were 3-4 times higher at forest-fragment sites than at unfragmented sites. Trillium seeds were -3 times more likely to be depredated in areas of elevated relative mouse abundance than in areas of lower relative abundance. Forest fragmentation has favored mouse populations, resulting in increased seed predation that may decrease recruitment rates and increase local extinction risks for Trillium.
-
HABITAT FRAGMENTATION AND DEMOGRAPHIC CHANGE FOR A COMMON PLANT: Trillium IN OLD-GROWTH FOREST
Ecology, 1998Co-Authors: Erik S. JulesAbstract:I studied the influence of forest fragmentation on an understory herb, Trillium ovatum, in the Siskiyou Mountains of Oregon, where logging practices over the past 35 yr have created a mosaic of fragments surrounded by clearcuts and tree plantations. The age of Trillium plants can be estimated by counting the annual constrictions on their rhizomes. Based on data collected by Whittaker in 1949 (i.e., pre-fragmentation) and a survey I conducted in 1995, I estimated that the process of clearcutting and subsequent conifer planting results in the mortality of almost all Trillium (∼97.6%). In general, the remaining plants are not recruiting new individuals, even in sites clearcut 30 yr ago. Thus, Trillium is restricted to smaller amounts of remnant, uncut forest. My study also demonstrated that populations in forest remnants that were within ∼65 m of forest-clearcut edges have had almost no recruitment of young plants since the time of the adjacent clearcutting, while forest interior populations contained higher recruitment levels. Projections based on these recruitment estimates indicated that edge populations will decline in size and interior populations will not decline. This study provides the first evidence of demographic changes in plant populations resulting from habitat fragmentation, and it offers evidence for the mechanisms responsible for such demographic changes.
Yoshiya Shimamoto - One of the best experts on this subject based on the ideXlab platform.
-
Variations in the breeding system and the population genetic structure of Trillium kamtschaticum (Liliaceae)
Heredity, 1996Co-Authors: Masashi Ohara, Haruko Takeda, Yoko Ohno, Yoshiya ShimamotoAbstract:Variations in the breeding system and the population genetic structure of Trillium kamtschaticum (Liliaceae)
Roger C. Anderson - One of the best experts on this subject based on the ideXlab platform.
-
Height of White‐Flowered Trillium (Trillium Grandiflorum) as an Index of Deer Browsing Intensity
Ecological Applications, 1994Co-Authors: Roger C. AndersonAbstract:The height of white-flowered Trillium (Trillium grandiflorum) is a useful indicator of deer browsing intensity. In their foraging activities deer select larger plants over smaller plants. Because flowering plants are larger than nonflowering plants, the number of plants in flower decreases with increasing browsing intensity. As browsing intensity increases, the height of the Trillium becomes shorter in successive growing seasons, presumably due to the loss of photosynthetic capacity and reduction in belowground re- sources. Trillium stem height was positively correlated with reproductive output by pe- rennial herbaceous plants and negatively correlated with the percent of the herbaceous understory that is browsed. This indicates change in stem height is an indication of the general status of the herbaceous flora as influenced by deer browsing. Based on deer pop- ulation densities associated with study sites supporting Trillium populations with stable stem heights and flowering plants, maintenance of deer densities of 4-6 individuals/km2 is recommended for deciduous forests in northeastern Illinois. In eastern United States, research workers who assume they are studying relatively undisturbed sites should be aware that intense deer browsing may have imposed an alteration on their study sites.
-
height of white flowered Trillium Trillium grandiflorum as an index of deer browsing intensity
Ecological Applications, 1994Co-Authors: Roger C. AndersonAbstract:The height of white-flowered Trillium (Trillium grandiflorum) is a useful indicator of deer browsing intensity. In their foraging activities deer select larger plants over smaller plants. Because flowering plants are larger than nonflowering plants, the number of plants in flower decreases with increasing browsing intensity. As browsing intensity increases, the height of the Trillium becomes shorter in successive growing seasons, presumably due to the loss of photosynthetic capacity and reduction in belowground re- sources. Trillium stem height was positively correlated with reproductive output by pe- rennial herbaceous plants and negatively correlated with the percent of the herbaceous understory that is browsed. This indicates change in stem height is an indication of the general status of the herbaceous flora as influenced by deer browsing. Based on deer pop- ulation densities associated with study sites supporting Trillium populations with stable stem heights and flowering plants, maintenance of deer densities of 4-6 individuals/km2 is recommended for deciduous forests in northeastern Illinois. In eastern United States, research workers who assume they are studying relatively undisturbed sites should be aware that intense deer browsing may have imposed an alteration on their study sites.
Shoichi Kawano - One of the best experts on this subject based on the ideXlab platform.
-
Life-history monographs of Japanese plants. 5: Trillium tschonoskii Maxim. (Trilliaceae)
Plant Species Biology, 2006Co-Authors: Masashi Ohara, Shoichi KawanoAbstract:Life-history characteristics and demography of Trillium tschonoskii (Trilliaceae) were studied and are described here. Trillium tschonoskii is the most wide-ranging species among Asiatic Trillium , ranging from southern Sakhalin, the Japanese Islands (excepting Kyushu) to the Korean Peninsula, Taiwan and further to inland China and the Himalayas. The ecological range of T. tschonoskii is broad, extending from lowland forests to montane and further to subalpine mixed forests consisting of conifers and subalpine birch, Betula ermani . This species is a typical polycarpic perennial, similar to all other Japanese Trillium species, and flowers in early to late April in lowland populations and in midJune to early July in subalpine habitats. Trillium tschonoskii typically has three white petals and three sepals, and its pollinators are diverse, for example, flies, beetles and bees such as Scatophagiae (Diptera), Oedemera lucidicollis (Coleoptera) and Andrena sp. (Hymenoptera). Pollen/ovule ratios of T. tschonoskii are approximately 700, thus T. tschonoskii is potentially an inbreeder. Seed outputs per plant are variable, 29–190 (mean 85.0) in 1980, and 28–168 (mean 79.8) in 1984. Seeds with a large soft juicy elaiosome attract ants, which are effective dispersal agents, but nocturnal elaiosome predators, mainly ground beetles, are also very active. Our long-term observations indicate that it takes approximately 10 years to reach a sexually mature stage and the life expectancy of mature plants is assumed to be exceedingly long, extending over 40 years.
-
molecular systematics of trilliaceae ii phylogenetic analyses of Trillium and its allies using sequences of rbcl and matk genes of cpdna and internal transcribed spacers of 18s 26s nrdna
Plant Species Biology, 1999Co-Authors: Shahrokh Kazempour Osaloo, Shoichi KawanoAbstract:Coding regions of the rbcL and matK genes of cpDNA and internal transcribed spacers (ITS) of nuclear ribosomal DNA were sequenced to study phylogenetic relationships within and among all four genera of Trilliaceae: Trillium, Paris, Daiswa and Kinugasa. The rbcL gene has evolved much slower than matK and in particular ITS; hence the phylogenetic trees based on the rbcL gene show a much lower resolution than trees based on either matK or ITS. The general topology of phylogenetic trees resulting from separate parsimony analyses of the matK and ITS sequences are relatively congruent, with the exception of the placement of T. pusillum. Both matK and ITS phylogenies reveal that T. rivale diverges at the base of the trees. In both trees, Paris, Daiswa and Kinugasa form a relatively weakly supported group. Within this group, the allo-octaploid Kinugasa japonica is the sister group of Daiswa species. The Paris‐Daiswa‐Kinugasa group, the major Trillium group, and T. undulatum and T. govanianum showed a loosely related topology, but their affinities are not evident according to these two molecular markers. However, phylogenetic analysis of amino acid sequences derived from matK shows that T. rivale together with clades T. undulatum‐T. govanianum, Daiswa‐Kinugasa and Paris is basally diverged as a sister group to the remainder of Trillium.
-
Molecular Systematics of Trilliaceae I. Phylogenetic Analyses of Trillium Using matK Gene Sequences
Journal of Plant Research, 1999Co-Authors: Shahrokh Kazempour Osaloo, Masashi Ohara, Frederick H. Utech, Shoichi KawanoAbstract:was conducted using 41 Trillium taxa and two out-group taxa (Veratrum maackii and Helonias bullata). A total of 1608 base pairs were analyzed and compared., and then there were 61 variable (36 informative) sites among Trillium species. Fifteen insertion/deletion events (indels) of six or fifteen base pairs were also detected. Phylogenetic analyses of the sequence data revealed that the subgenus Phyllantherum (sessile-flowered species) forms a distinct monophyletic group, whereas the subgenus Trillium (pedicellate-flowered species) does not form a monophyletic group, and is composed of three distinct groups and three basally located species in the tree: (1) the Erectum group, (2) the Grandiflorum group, and (3) the Pusillum group and (4) the three species, including T. govanianum, T. undulatum, and T. rivale. T .rivale appears to be the most basally diverged and a very specialized taxon among the ingroup members. Our matK data indicated that the closest relative of the subgenus Phyllantherum is the Grandiflorum group. The results are concordant with the results of the RFLP analysis of cpDNA and also more or less with those of the cladistic analysis of morphological characters.
-
Evolutionary Biology of Trillium and Related Genera (Trilliaceae) II. Cladistic Analyses on Gross Morphological Characters, and Phylogeny and Evolution of the Genus Trillium
Plant Species Biology, 1995Co-Authors: Shoichi Kawano, Hidetoshi KatoAbstract:Abstract Cladistic analyses were conducted based upon 22 gross morphological and one floral odor characters for 42 Trillium species, one Kinugasa, one Daiswa, and two Paris species of the Trilliaceae, using Daiswa and Paris as outgroups. The cladistics provided an informative result with regard to the affinity and phylogeny of the taxa referred to the genus Trillium and related genera in the Trilliaceae, suggesting that Trillium is composed of four major infrageneric groups: (1) the pedicellate-flowered group represented by the Erectum group including 13 species, (2) the Undulatum group, a loosely clustered paraphyletic group including five species, (3) the Govanianum group consisting of only two species, and (4) the Sessile group including 22 species. The monophyly of the Sessile group is very evident. The results are concordant with the earlier results of the RFLP analysis of cpDNA conducted by us. It is noteworthy, however, that the pedicellate-flowered group of Trillium is not simply monophyletic, as was assumed previously, but instead consists of at least three to four distinct groups as noted above. The implications and limitations of using distantly related genera, such as Daiswa or Paris as outgroups, in the cladistic analysis were also argued.
