116 research outputs found

    A new species of winged fruit from the Miocene of Ecuador: Tipuana ecuatoriana (Leguminosae)

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141584/1/ajb213863.pd

    Agricultural natural enemies benefit predominantly from broader scales of environmental heterogeneity: A quantitative review

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    Naturally occurring predator and parasitoid communities are well known to respond to multiple scales of environmental heterogeneity within and around agroecoystems, yet our understanding of which scales are most influential on different functional guilds of enemies is limited. Using vote-counting methodology, we synthesized the results from 40 empirical studies that observed how natural enemy richness, diversity, or parasitism rate is affected by environmental heterogeneity at a local scale (e.g. a focal field), an intermediate scale (e.g. habitat in immediate proximity of a focal field), and landscape scale (e.g. habitat within \u3e200 m radius around focal field). Heterogeneity at all scales was more commonly beneficial than antagonistic to natural enemies as a whole, where positive responses were always significantly larger than negative responses. However, when using a conservative approach of comparing the positive and ‘non-positive’ (combined neutral and negative responses), landscape heterogeneity was the only scale where positive responses significantly outweighed non-positive responses. The same trend held for natural enemy guilds; though all guilds had more positive than negative responses to all scales of heterogeneity, intermediate and landscape scales were the only scales where any guild had significantly more positive than non-positive responses. These results suggest the importance of incorporating geographically large-scale strategies when seeking to conserve natural enemies and enhance or sustain conservation biological control services

    Miocene winged fruits of Loxopterygium (Anacardiaceae) from the Ecuadorian Andes

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141449/1/ajb21767.pd

    No evidence that elevated CO\u3csub\u3e2\u3c/sub\u3e gives tropical lianas an advantage over tropical trees

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    Recent studies indicate that lianas are increasing in size and abundance relative to trees in neotropical forests. As a result, forest dynamics and carbon balance may be altered through liana‐induced suppression of tree growth and increases in tree mortality. Increasing atmospheric CO2 is hypothesized to be responsible for the increase in neotropical lianas, yet no study has directly compared the relative response of tropical lianas and trees to elevated CO2. We explicitly tested whether tropical lianas had a larger response to elevated CO2 than co‐occurring tropical trees and whether seasonal drought alters the response of either growth form. In two experiments conducted in central Panama, one spanning both wet and dry seasons and one restricted to the dry season, we grew liana (n = 12) and tree (n = 10) species in open‐top growth chambers maintained at ambient or twice‐ambient CO2 levels. Seedlings of eight individuals (four lianas, four trees) were grown in the ground in each chamber for at least 3 months during each season. We found that both liana and tree seedlings had a significant and positive response to elevated CO2 (in biomass, leaf area, leaf mass per area, and photosynthesis), but that the relative response to elevated CO2 for all variables was not significantly greater for lianas than trees regardless of the season. The lack of differences in the relative response between growth forms does not support the hypothesis that elevated CO2 is responsible for increasing liana size and abundance across the neotropics

    Habitat‐related error in estimating temperatures from leaf margins in a humid tropical forest

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142103/1/ajb21096.pd

    Higher rates of liana regeneration after canopy fall drives species abundance patterns in central Amazonia

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    In tropical rainforest, most vascular plants have some capacity to resprout, and lianas are often effective resprouters after canopy fall. However, the diversity of resprouting responses of liana species and the consequence for plant persistence are poorly understood. We hypothesized that variation in regeneration among liana species causes differences in liana species abundance in tropical rainforest through differential resprouting capacity, such that liana species with higher densities produce more resprouts after canopy falls.We applied a manipulative field experiment investigating the effect of different levels of disturbance on the production of resprouts and adventitious roots in 10 liana species of the tribe Bignonieae (Bignoniaceae) with contrasting abundances in central Amazonia. We selected 15 individuals of each species and assigned the lianas to three distinct conditions: (a) total canopy fall with lianas severely damaged and detached from trees; (b) partial fall of lianas, without visible damage; and (c) intact lianas (control). We tested whether liana species regeneration patterns were related to species density. Liana species density was calculated using previous research on liana species distribution in 30 1‐ha plots systematically distributed in a 6 × 6 km2 grid at the Ducke Reserve.The number of aerial resprouts produced by lianas under the total canopy fall treatment was twice that of plants under lower levels of disturbance, while the production of adventitious roots did not differ among treatments. Liana species showed different intensities of resprouting, and species with higher average densities on the forest landscape had more resprouts after the total canopy fall treatment.Synthesis. Our results shed new light on the factors that influence liana species abundance, highlighting the role of resprouting after canopy fall and its variation among liana species. Resprouting mitigates the negative effects of canopy damage, suggesting that the impact of increased tree fall disturbances over time, which has been attributed to Amazonian forests in the literature, may increase already abundant liana species with effective resprouting capacity. We identify liana species that are more resilient to disturbance and may alter forest dynamics during climatic change.Our results shed new light on the factors that influence liana species abundance, highlighting the role of resprouting after canopy fall and its variation among liana species. Resprouting mitigates the negative effects of canopy damage, suggesting that the impact of increased tree fall disturbances over time, which has been attributed to Amazonian forests in the literature, may increase already abundant liana species with effective resprouting capacity. We identify liana species that are more resilient to disturbance and may alter forest dynamics during climatic change.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155931/1/jec13345_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155931/2/jec13345.pd

    THE MICHIGAN BIG WOODS RESEARCH PLOT AT THE EDWIN S. GEORGE RESERVE, PINCKNEY, MI, USA

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    The Michigan Big Woods research plot is a 23-ha forest dynamics research area at the Edwin S. George Reserve in Pinckney, MI, USA and is part of the Smithsonian Institution’s ForestGEO network of research stations. The plot’s freestanding woody vegetation (trees and shrubs) were censused three times, in 2003, 2008–2010, and 2014; lianas were censused on 20 ha from 2017 to 2018.http://deepblue.lib.umich.edu/bitstream/2027.42/156251/1/MP 207.pdfDescription of MP 207.pdf : Main ArticleSEL

    Floral and environmental gradients on a Late Cretaceous landscape

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116378/1/ecm201282123.pd

    Cucurbitaceae, Gurania Cogn., for southern Amazonia, Mato Grosso, Brazil

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    We found six species of the genus Gurania that are described here as new records for the state of Mato Grosso, Central Brazil. The species of Gurania recorded here occur in the north of Mato Grosso state, Brazil in the biome recognized as “Floresta Amazônica”. This is an area of southern Amazonia that has been poorly inventoried. We carried out the surveys in permanent plots using the RAPELD-PPBio system and along trails giving access to the permanent plots
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