Germination and seedling survivorship of three Tillandsia species in the cloud-forest canopy

2012 ◽  
Vol 28 (4) ◽  
pp. 423-426 ◽  
Author(s):  
Tarin Toledo-Aceves ◽  
José G. García-Franco ◽  
Siunelly Landero Lozada ◽  
María Luisa León Mateos ◽  
Keith MacMillan
Keyword(s):  
Forest Canopy ◽  
Seedling Survival ◽  
Cloud Forest ◽  
Survival Rates ◽  
Species Abundance ◽  
Limiting Factors ◽  
Heterogeneous Distribution ◽  
Seedling Survivorship ◽  
Forest Condition ◽  
Morphological And Physiological Traits

Low germination and seedling survival probabilities are reported in various species of epiphytic bromeliad (Benzing 1978, Hietz et al. 2011, Toledo-Aceves & Wolf 2008, Winkler et al. 2005; but see Cascante-Marín et al. 2008). If germination and seedling survival are limiting factors in the life cycle, differential germination and seedling survival between species should be reflected in the relative abundance of established plants (Cascante-Marín et al. 2006, 2008) and in their presence or absence in secondary vegetation (Hietz et al. 2011), while differential germination within the tree would be expected to contribute to a heterogeneous distribution of established plants within the canopy (Hietz et al. 2011, Zotz & Vollrath 2002). Many factors influence the performance and distribution of epiphytes, including forest condition, disturbance type, distance from seed source, tree size and species, microclimate, epiphyte population dynamics and physiology (Cascante-Marín et al. 2009, Hietz et al. 2011, Valencia-Diaz et al. 2010, Zotz & Hietz 2001). In this study, we tested whether germination and seedling survival rates differ between the epiphytic bromeliads Tillandsia multicaulis Steud., T. punctulata Schldl. & Cham. and T. butzii Mez, and whether species abundance reflects the ability to germinate and survive as seedlings within the cloud-forest canopy. We also explore how morphological and physiological traits of the studied species can influence their early establishment.

scholarly journals Synthesizing published knowledge of boreal forest cover change for large-scale landscape dynamics modelling

2003 ◽  
Vol 79 (1) ◽  
pp. 132-146 ◽  
Author(s):  
Dennis Yemshanov ◽  
Ajith H Perera
Keyword(s):  
Boreal Forest ◽  
Large Scale ◽  
Forest Canopy ◽  
Forest Cover ◽  
Forest Succession ◽  
Simulation Models ◽  
Limiting Factors ◽  
Sources Of Information ◽  
Forest Cover Change ◽  
Discrete State

We reviewed the published knowledge on forest succession in the North American boreal biome for its applicability in modelling forest cover change over large extents. At broader scales, forest succession can be viewed as forest cover change over time. Quantitative case studies of forest succession in peer-reviewed literature are reliable sources of information about changes in forest canopy composition. We reviewed the following aspects of forest succession in literature: disturbances; pathways of post-disturbance forest cover change; timing of successional steps; probabilities of post-disturbance forest cover change, and effects of geographic location and ecological site conditions on forest cover change. The results from studies in the literature, which were mostly based on sample plot observations, appeared to be sufficient to describe boreal forest cover change as a generalized discrete-state transition process, with the discrete states denoted by tree species dominance. In this paper, we outline an approach for incorporating published knowledge on forest succession into stochastic simulation models of boreal forest cover change in a standardized manner. We found that the lack of details in the literature on long-term forest succession, particularly on the influence of pre-disturbance forest cover composition, may be limiting factors in parameterizing simulation models. We suggest that the simulation models based on published information can provide a good foundation as null models, which can be further calibrated as detailed quantitative information on forest cover change becomes available. Key words: probabilistic model, transition matrix, boreal biome, landscape ecology

scholarly journals Survival of Longleaf and Loblolly Pines Planted at Two Spacings in an East Texas Bahiagrass Silvopasture

2008 ◽  
Vol 32 (1) ◽  
pp. 44-45
Author(s):  
Brian P. Oswald ◽  
Kenneth W. Farrish ◽  
Micah-John Beierle
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Seedling Survival ◽  
Survival Rates ◽  
Pinus Palustris ◽  
Mortality Rates ◽  
Paspalum Notatum ◽  
East Texas ◽  
Forage Production ◽  
Loblolly Pines

Abstract The practice of combining intensive timber and forage production on the same site, a silvopasture system, offers landowners the potential for diversification of income. The establishment of such a system in a pasture setting offers unique challenges compared with traditional timber or forage systems. In 2003, a silvopasture demonstration was established south of Carthage, Texas, in a pasture dominated by bahiagrass (Paspalum notatum). Four replications of treatments composed of open pasture, longleaf (Pinus palustris) and loblolly (Pinus taeda) pine planted at a traditional spacing, and longleaf and loblolly pine planted at a silvopasture spacing were established. Due to high mortality rates, replanting of trees occurred in 2004 and 2005. Third-year seedling survival was highest for loblolly pine in both planting systems, and forage production levels did not significantly differ among treatments. Wild hog damage contributed to the low longleaf pine seedling survival rates.

scholarly journals A Multi-Objective Approach for Anti-Osteosarcoma Cancer Agents Discovery through Drug Repurposing

2020 ◽  
Vol 13 (11) ◽  
pp. 409
Author(s):  
Alejandro Cabrera-Andrade ◽  
Andrés López-Cortés ◽  
Gabriela Jaramillo-Koupermann ◽  
Humberto González-Díaz ◽  
Alejandro Pazos ◽  
...  
Keyword(s):  
Desirability Function ◽  
Survival Rates ◽  
Drug Repurposing ◽  
Limiting Factors ◽  
Antineoplastic Drugs ◽  
Final Model ◽  
Multi Objective ◽  
Acute Complications ◽  
Objective Model ◽  
New Strategies

Osteosarcoma is the most common type of primary malignant bone tumor. Although nowadays 5-year survival rates can reach up to 60–70%, acute complications and late effects of osteosarcoma therapy are two of the limiting factors in treatments. We developed a multi-objective algorithm for the repurposing of new anti-osteosarcoma drugs, based on the modeling of molecules with described activity for HOS, MG63, SAOS2, and U2OS cell lines in the ChEMBL database. Several predictive models were obtained for each cell line and those with accuracy greater than 0.8 were integrated into a desirability function for the final multi-objective model. An exhaustive exploration of model combinations was carried out to obtain the best multi-objective model in virtual screening. For the top 1% of the screened list, the final model showed a BEDROC = 0.562, EF = 27.6, and AUC = 0.653. The repositioning was performed on 2218 molecules described in DrugBank. Within the top-ranked drugs, we found: temsirolimus, paclitaxel, sirolimus, everolimus, and cabazitaxel, which are antineoplastic drugs described in clinical trials for cancer in general. Interestingly, we found several broad-spectrum antibiotics and antiretroviral agents. This powerful model predicts several drugs that should be studied in depth to find new chemotherapy regimens and to propose new strategies for osteosarcoma treatment.

Germination, survival, and early growth of red alder seedlings in the central Coast Range of Oregon

1995 ◽  
Vol 25 (10) ◽  
pp. 1639-1651 ◽  
Author(s):  
Sybille Haeussler ◽  
John C. Tappeiner II ◽  
Brian J. Greber
Keyword(s):  
Soil Moisture ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Survival Rates ◽  
Moisture Stress ◽  
Coast Range ◽  
Seedling Mortality ◽  
Central Coast ◽  
Red Alder

Effects of forest disturbance and soil moisture levels on establishment of red alder (Alnusrubra Bong.) seedlings were studied at four sites representing a climatic moisture gradient within the central Coast Range of Oregon. On average, there was no difference in seedling emergence between recent clearcuts and second-growth forests, but emergence was much higher on mineral soil than on organic seedbeds. Emergence, on both types of seedbed, was positively correlated with spring soil moisture conditions (R2 = 0.60). Seedling survival, on the other hand, differed greatly between clearcut and forest. In clearcuts, heat and drought injuries were the primary causes of seedling mortality. In the forest, seedlings had poor vigour and quickly succumbed to pathogens, herbivores, and rain splash. First-year survival rates were strongly correlated with minimum summer soil moisture levels (R2 = 0.71). Height growth of seedlings on clearcuts (2–5 cm after 1 year; 8–23 cm after 2 years) was much slower than rates typically described for red alder. Best establishment occurred on skid trails and landings, suggesting that young seedlings may suffer less from heat or moisture stress on these heavily disturbed microenvironments.

Testing pathogen host specificity: a reciprocal field experiment in two types of tropical forest on Hainan, China

2013 ◽  
Vol 29 (6) ◽  
pp. 541-549 ◽  
Author(s):  
Wen Zheng ◽  
He He ◽  
Lin Xiao ◽  
Shixiao Yu
Keyword(s):  
Seed Germination ◽  
Host Specificity ◽  
Tree Species ◽  
Rain Forest ◽  
Forest Type ◽  
Seedling Survival ◽  
Cloud Forest ◽  
Soil Pathogens ◽  
Montane Rain Forest ◽  
Adult Trees

Abstract:The Janzen–Connell hypothesis suggests that highly specific pathogens decrease seedling survival close to the parent plant; however, the underlying mechanism remains unclear. Here, we tested the host specificity of soil pathogens to germinating seeds of Cyclobalanopsis fleuryi and Cryptocarya chinensis in tropical montane rain forest and cloud forest on Hainan, south China. Rhizospheric soils surrounding eight adult trees per species were collected in each forest type and divided into five soil treatments: parent, fungicide-sterilized, autoclave-sterilized, Fusarium-added and Pythium-added soils. Surface-sterilized seeds were sown in each of the five soil treatments and grown in two forest types. The seed germination percentages were significantly higher in sterilized soils (C. fleuryi, 41.5%; C. chinensis, 29.4%) than in non-sterilized soils (C. fleuryi, 28.3%; C. chinensis, 17.1%) in montane rain forest. The seed germination percentages in rhizospheric soil of conspecific parent trees were significantly lower in montane rain forest (C. fleuryi, 17.3%; C. chinensis, 10.5%) than in cloud forest (C. fleuryi, 37.1%; C. chinensis, 21.1%). Our results also suggest that the level of pathogen activity in each tree species varies depending on the environment. Our results support the hypothesis that host-specific pathogens shape tree species composition by differentially affecting seed germination under different environmental conditions.

Burrow occupancy and productivity at coastal sooty shearwater (Puffinus griseus) breeding colonies, South Island, New Zealand: can mark - recapture be used to estimate burrowscope accuracy?

2003 ◽  
Vol 30 (4) ◽  
pp. 377 ◽  
Author(s):  
Chris Jones ◽  
Susan Bettany ◽  
Henrik Moller ◽  
David Fletcher ◽  
Justine de Cruz
Keyword(s):  
New Zealand ◽  
Survival Rates ◽  
Species Abundance ◽  
Adult Survival ◽  
Egg Survival ◽  
Global Pattern ◽  
Data Set ◽  
Mark Recapture ◽  
Mammalian Predators ◽  
Occupancy Rates

Breeding colonies of sooty shearwaters ('muttonbird', tïtï, Puffinus griseus) on mainland New Zealand have declined in recent years. New data on burrow occupancy and colony productivity for seven sooty shearwater breeding colonies on the coast of Otago, New Zealand for the 1996–97 and 1997–98 breeding seasons are presented and analysed as part of a five-year data set. Detection of a burrow's occupants using a fibre-optic burrowscope may underestimate absolute occupancy rates, but is still of value in the analysis of trends. Detection probabilities estimated by the novel use of mark–recapture models corresponded with those of previous studies of the technique's accuracy. Mainland declines are associated with a lack of control of introduced mammalian predators at most mainland colonies superimposed on a global pattern of decline in the species' abundance. Large numbers of recovered carcasses and an absence of burrow activity at two small mainland colonies show the decline to extinction of these colonies over the five years of collecting data. At one mainland colony with intensive predator control, survival rates and parameter variances are comparable with those found on a predator-free offshore island. All other mainland colonies showed negligible breeding success. There was a significant positive relationship between egg survival and an index of relative adult survival, with an apparent threshold below which few eggs hatch. Adult survival during the breeding season is likely to be the most important parameter in maintaining a colony's viability.

Growth and seasonality of seedlings and juveniles of primary species of a cloud forest in northern Venezuela

1992 ◽  
Vol 8 (3) ◽  
pp. 299-305 ◽  
Author(s):  
Saúl Flores
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Forest Canopy ◽  
Slow Growth ◽  
Cloud Forest ◽  
Primary Root ◽  
Leaf Number ◽  
First Year ◽  
Leaf Production ◽  
Relative Growth

ABSTRACTThe survival, height and leaf production of seedlings and juveniles of Aspidosperma fendleri and Richena grandis were measured monthly for three years after germination. During the first year, some seedlings and juveniles of Aspidosperma fendleri were collected and the number of rootlets, the primary root length and the shoot: root ratio were determined.Both species show periodicity in growth but their relative growth rate differs between species. For Aspidosperma fendleri, the highest relative growth rate (0.313 y-1) was found for individuals grown under greenhouse conditions followed by individuals growing in an old forest gap (0.143 y-1) and finally individuals under the forest canopy (0.137 y-1). For Richeria grandis, the relative growth rate under the forest canopy was 0.261 y-1. Leaf production for Aspidosperma fendleri in the forest (natural conditions) was 4.39 total mean leaf number for five years and 5.46 total mean leaf number under greenhouse conditions. For Richeria grandis it was 5.34 mean leaf production for four years. The root: shoot ratio for Aspidosperma fendleri was constant during the observation year. Aspidosperma fendleri showed a lower number of rootlets than did Richeria grandis. There was an inverse relationship between growth and survival during the dry season. During this period, mortality was higher and the highest mortality occurred during the first year when the total relative growth rate was highest.Slow growth is evident in both species. This mechanism may represent an adaptive advantage to remain dormant until there is an opening in the forest canopy. Since the seeds of Aspidosperma fendleri and Richeria grandis are highly vulnerable to predators and pathogens, slow growth as seedlings and juveniles allows them to survive, and contributes to regeneration in cloud forest.

scholarly journals Effect of Density on Mediterranean Pine Seedlings Using the Nelder Wheel Design: Analysis of Survival and Early Growth

2021 ◽  
Author(s):  
Irene Ruano ◽  
Valentín Pando ◽  
Felipe Bravo
Keyword(s):  
Pinus Pinaster ◽  
Proportional Hazards ◽  
Pinus Halepensis ◽  
Seedling Survival ◽  
Survival Rates ◽  
Mediterranean Ecosystems ◽  
Early Growth ◽  
Cox Proportional Hazards ◽  
Basal Diameter ◽  
Cox Proportional Hazards Models

Abstract Background: There is growing interest in mixed-species forests but a lack of studies that analyse them for regeneration phases or any stage other than mature stands. Information is scarce about relatively unproductive species such as Pinus pinaster and Pinus halepensis in Mediterranean ecosystems. The objective of this study was to investigate inter- and intra-specific interactions of both species in different tree densities during the first years of establishment. Five Nelder wheel plots were planted to test densities ranging from 1000 to 80000 seedlings/ha and simulate establishment sub-processes at high densities. Pinus pinaster and Pinus halepensis were mixed along the spokes, to obtain three mixture levels in which 100%, 80% or 60% of the seedlings were of the same species. Cox proportional-hazards models and binomial logistic regressions were fitted to analyse seedling survival. Early growth (basal diameter and height at one and four years after plantation) was analysed by fitting linear mixed-effects models. Results: Pinus halepensis showed higher survival rates and basal diameter increments but more time is needed to know how Pinus pinaster responds to density and mixture. Conclusions: Both competitive and facilitating seedling interactions were observed at higher densities, which facilitate seedling survival but decrease early growth. Pinus halepensis showed higher survival rates and basal diameter increments but more time is necessary to determine Pinus pinaster response to density and mixture.

scholarly journals Fecundity of Winged Euonymus Cultivars and Their Ability to Invade Various Natural Environments

HortScience ◽  
2012 ◽  
Vol 47 (8) ◽  
pp. 1029-1033 ◽  
Author(s):  
Mark H. Brand ◽  
Jessica D. Lubell ◽  
Jonathan M. Lehrer
Keyword(s):  
Seed Production ◽  
Seedling Survival ◽  
Germination Rate ◽  
Survival Rates ◽  
Natural Environments ◽  
Euonymus Alatus ◽  
Demographic Models ◽  
Non Invasive ◽  
Deciduous Woodland ◽  
Northern United States

Winged euonymus [Euonymus alatus (Thunb.)] is an important landscape shrub that has demonstrated its potential to be invasive in numerous states across the central and northern United States. Nine cultivars were evaluated for their potential to produce fruits and seeds in a randomized, replicated field planting. Seeds from all cultivars were evaluated for germination rate and initial survival in a deciduous woodland. Seeds collected from ‘Compactus’ were also sown in five natural environments (full sun meadow, edge of woods, moist woods, dry woods, pine woods) to determine which habitat types support its germination and establishment. Seed production for cultivars varied from 981 to 6090 seeds per plant. The dry deciduous woods and pine woods were the only environments that supported significant germination rates that could be as high as 37.8%. Seedling survival was at least 77% in the deciduous dry woods and at least 55% in the pine woods. In the first replication, establishment rates for cultivars in the dry deciduous woods ranged from a low of 6.5% for ‘Odom’ Little Moses™ to a high of 42.5% for ‘Monstrosus’. In the second replication, all cultivars achieved over 30% establishment and most exceeded 40% establishment. An estimate of the annual seedling contribution per plant per cultivar was calculated by combining seed production data with establishment data for each cultivar. This estimate was predicted to range from 588 to 3763 and therefore none of the nine cultivars evaluated should be considered non-invasive based on our findings. Our findings show that germination and seedling survival rates are high for E. alatus and because the species is long-lived, cultivars will likely have to be completely seed-sterile to be considered non-invasive according to demographic models.

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