scholarly journals Insect herbivores increase mortality and reduce tree seedling growth of some species in temperate forest canopy gaps

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3102 ◽  
Author(s):  
Nathan P. Lemoine ◽  
Deron E. Burkepile ◽  
John D. Parker
Keyword(s):  
Tree Species ◽  
Forest Canopy ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Tree Seedlings ◽  
Insect Herbivores ◽  
Pioneer Species ◽  
Tree Seedling ◽  
Selective Predation ◽  
Forest Diversity

Insect herbivores help maintain forest diversity through selective predation on seedlings of vulnerable tree species. Although the role of natural enemies has been well-studied in tropical systems, relatively few studies have experimentally manipulated insect abundance in temperate forests and tracked impacts over multiple years. We conducted a three-year experiment (2012–2014) deterring insect herbivores from seedlings in new treefall gaps in deciduous hardwood forests in Maryland. During this study, we tracked recruitment of all tree seedlings, as well as survivorship and growth of 889 individual seedlings from five tree species:Acer rubrum,Fagus grandifolia,Fraxinusspp.,Liriodendron tulipifera, andLiquidambar styraciflua. Insect herbivores had little effect on recruitment of any tree species, although there was a weak indication that recruitment ofA. rubrumwas higher in the presence of herbivores. Insect herbivores reduced survivorship ofL. tulipifera, but had no significant effects onA. rubrum,Fraxinusspp.,F. grandifolia, orL. styraciflua. Additionally, insects reduced growth rates of early pioneer speciesA. rubrum,L. tulipifera, andL. styraciflua, but had little effect on more shade-tolerant speciesF. grandifoliaandFraxinusspp. Overall, by negatively impacting growth and survivorship of early pioneer species, forest insects may play an important but relatively cryptic role in forest gap dynamics, with potentially interesting impacts on the overall maintenance of diversity.

Distribution of primary forest plant species in a 19-year old secondary forest in French Guiana

1998 ◽  
Vol 14 (3) ◽  
pp. 323-340 ◽  
Author(s):  
D. TORIOLA ◽  
P. CHAREYRE ◽  
A. BUTTLER
Keyword(s):  
Distribution Pattern ◽  
Tree Species ◽  
French Guiana ◽  
Forest Canopy ◽  
Secondary Forest ◽  
Primary Forest ◽  
Pioneer Species ◽  
Forest Species ◽  
Mature Forest ◽  
Height Class

Secondary succession in a 19-y old tropical rainforest of French Guiana was investigated through the distribution pattern of primary forest species. The experimental plot of 25 ha was logged to simulate conditions of a paper pulp cut. Enumeration of all plants of height ≥ 50 cm in 52 subplots 10 m × 10 m indicated the number of species and individuals in five species categories; short-lived pioneer species, pioneer species that persist in mature forest, primary forest species capable of germinating in shade, primary forest species that indicate a preference for clearings (small gaps) in mature forest and understorey primary forest species. Change in proportion of the most abundant species (≥ 1 cm dbh) over the last 15 y indicated a decrease in short-lived pioneer species and an increase in pioneers that can persist in the mature forest. Proportion of species categories per height class indicated that primary forest species were mainly found in the lower height class in this forest which is largely dominated by secondary forest tree species forming a canopy that rarely exceeds 20 m. Individuals of primary forest species were encountered on ARBOCEL as sprouts from large stumps, sprouts from juveniles or as untraumatised saplings or juveniles. The distribution pattern in a 4-ha area of 11 selected primary forest canopy tree species revealed an overall trend in recolonisation of this species category in the secondary forest. Considered individually, the clustered distribution of stems of Eperua grandiflora showed the importance of regeneration through sprouting or remaining individuals. The gradient distribution, oriented from the edge to the centre of the studied plot, and displayed by the stem densities of Virola michelii, suggested a recent progressive dispersal of seeds. A more dynamic recolonisation front was observed for the primary forest understorey species Cassipourea guianensis and was probably linked to both the initial logging conditions and the fact that this species fruits when relatively young.

Tree seedling growth and mortality responses to manipulations of calcium and aluminum in a northern hardwood forest

2002 ◽  
Vol 32 (6) ◽  
pp. 954-966 ◽  
Author(s):  
Richard K Kobe ◽  
Gene E Likens ◽  
Christopher Eagar
Keyword(s):  
Acer Saccharum ◽  
Abies Balsamea ◽  
Fagus Grandifolia ◽  
Diameter Growth ◽  
Tree Seedlings ◽  
Betula Alleghaniensis ◽  
Hubbard Brook Experimental Forest ◽  
Tree Seedling ◽  
Soil Calcium ◽  
Dependent Growth

To assess potential forest compositional responses to exchangeable soil calcium (Caexch) and aluminum (Alexch), we characterized light-dependent growth and mortality of tree seedlings under amendments of CaCl2 and AlCl3 at Hubbard Brook Experimental Forest (HBEF), New Hampshire, U.S.A. Seedlings of Acer saccharum Marsh., Fagus grandifolia Ehrh., Betula alleghaniensis Britton, Abies balsamea (L.) Mill., and Picea rubens Sarg. were transplanted into field plots, which were randomly assigned to control, CaCl2, or AlCl3 treatments and stratified across <1 to 35% full sun. Acer saccharum and P. rubens exhibited significantly higher mortality in Al-amended than Ca-amended or control plots. Acer saccharum showed significant increases in relative diameter growth in Ca-amended plots versus controls; all other species showed nonsignificantly higher relative diameter growth under Ca amendments. We incorporated significant seedling responses into a model of forest dynamics (SORTIE) to assess potential changes in species composition under Alexch increases and Caexch losses. SORTIE predicts that further increases in Alexch would have negligible effects on canopy composition within 200 years but that the estimated Caexch depleted from HBEF between 1968 and 1995 and its influence on seedling dynamics could lead to substantial decreases in A. saccharum canopy dominance within a single forest generation (<125 years).

Direct and indirect effects of a dense understory on tree seedling recruitment in temperate forests: habitat-mediated predation versus competition

2008 ◽  
Vol 38 (6) ◽  
pp. 1634-1645 ◽  
Author(s):  
Alejandro A. Royo ◽  
Walter P. Carson
Keyword(s):  
Indirect Effects ◽  
Vegetation Cover ◽  
Acer Saccharum ◽  
Resource Competition ◽  
Seedling Recruitment ◽  
Plant Cover ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Tree Seedling ◽  
The Impact

In forests characterized by a dense woody and herbaceous understory layer, seedling recruitment is often directly suppressed via interspecific competition. Alternatively, these dense layers may indirectly lower tree recruitment by providing a haven for seed and seedling predators that prey on neighboring plant species. To simultaneously test for resource competition and indirect, habitat-mediated effects, we factorially manipulated understory plant cover (removed versus intact) and predation (exclosures versus controls) at three forested sites. We found that vegetation cover created privileged foraging areas that increased seed removal and seedling predation rates. Predator preference was directly related to seed size with larger seeded species including Prunus serotina Ehrh. and Fagus grandifolia Ehrh. removed more readily than smaller seeded species such as Fraxinus americana L. We found strong species-specific evidence for habitat-mediated indirect effects; establishment of P. serotina and Acer saccharum Marsh.was significantly lower under an intact hay-scented fern ( Dennstaedtia punctilobula (Michx.) T. Moore) canopy when small mammals were present. Competition also played a strong role; both P. serotina and Acer rubrum L. survival as well as A. rubrum emergence were reduced under a fern canopy with or without seed predators. The impact of habitat-mediated indirect effects and resource competition appear to vary predictably based upon predator preferences and differences in the timing of woody seed dispersal and germination relative to vegetation cover phenology. Overall, our results suggest that habitat-mediated indirect effects may be common and occur wherever vegetation provides the potential for creating privileged foraging areas.

A decade of canopy-tree seedling survival and growth in two Bornean rain forests: persistence and recovery from suppression

2002 ◽  
Vol 18 (5) ◽  
pp. 645-658 ◽  
Author(s):  
Lisa J. Delissio ◽  
Richard B. Primack ◽  
Pamela Hall ◽  
H. S. Lee
Keyword(s):  
Tree Species ◽  
National Park ◽  
Seedling Survival ◽  
High Growth ◽  
Tree Seedlings ◽  
Gap Formation ◽  
Rain Forests ◽  
Tree Seedling ◽  
Dipterocarp Forests ◽  
Census Interval

The population dynamics of 8500 shade-tolerant tree seedlings of 13 tree species were followed for 10 years at rain forests in Lambir Hills National Park and Bako National Park, Malaysian Borneo. Since these dipterocarp forests have lower rates of canopy gap formation than do rain forests elsewhere, tree seedling biology was predicted to differ. Approximately 50% of seedlings present in 1986 were still alive in 1996. Seven out of thirteen had seedling populations composed predominantly of individuals that were at least 10 years old. These seedlings can undergo alternating periods of relatively rapid and slow growth. Many seedlings that grew rapidly in the first census interval survived through a period of suppression in the second census interval, and conversely many seedlings with a history of suppression had exceptionally high growth in the final census interval. Seedlings of South-East Asian forest tree species are long-lived and appear to be adapted to long periods of suppression in the understorey.

Effects of canopy openings on tree seed germination in a Malaysian dipterocarp forest

1990 ◽  
Vol 6 (2) ◽  
pp. 203-217 ◽  
Author(s):  
James W. Raich ◽  
Gong Wooi Khoon
Keyword(s):  
Seed Germination ◽  
Shade Tolerance ◽  
Forest Canopy ◽  
Tree Seedlings ◽  
Secondary Forests ◽  
Pioneer Species ◽  
Dipterocarp Forest ◽  
Treefall Gaps ◽  
Closed Canopy ◽  
Lowland Forests

ABSTRACTThe germination of 43 tree species native to the lowland forests of Malaysia was monitored on forest soil in trays placed in closed-canopy forest, an artificial forest gap, and a large clearing. Germination varied significantly among habitats, with only seven species germinating well in all three sites. Seed germination of most species demonstrated clear patterns of shade tolerance or intolerance identical to those long recognized for tree seedlings. Favoured locations for germination were similar to known distributional patterns of adult individuals in mature and secondary forests. Most forest canopy species germinated in the gap, but germination in the large clearing was dramatically reduced or nil; the regeneration of these species in large clearings will be severely retarded even when seeds are present. Canopy-induced inhibition of germination was apparent in several pioneer species; seeds moved from the forest into the gap or clearing germinated rapidly. Results indicate that natural treefall gaps do not inhibit the germination of most species, but do allow pioneer species to germinate, and therefore regenerate. Although germination occurred in all three locations, the level of germination for particular species varied greatly among habitats. We conclude that germination requirements play a very important role in controlling the species composition of regeneration in forest understorey, gap, and large clearing habitats.

Above- and below-ground competition in high and low irradiance: tree seedling responses to a competing liana Byttneria grandifolia

2008 ◽  
Vol 24 (05) ◽  
pp. 517-524 ◽  
Author(s):  
Ya-Jun Chen ◽  
Frans Bongers ◽  
Kun-Fang Cao ◽  
Zhi-quan Cai
Keyword(s):  
Leaf Area ◽  
Tree Species ◽  
Morphological Traits ◽  
Root Competition ◽  
Tree Seedlings ◽  
Tree Seedling ◽  
Relative Growth Rates ◽  
Shoot Competition ◽  
Shade Tolerant Species ◽  
Below Ground

Abstract:In tropical forests, trees compete not only with other trees, but also with lianas, which may limit tree growth and regeneration. Liana effects may depend on the availability of above- and below-ground resources and differ between tree species. We conducted a shade house experiment to test the effect of light (4% and 35% full sun, using neutral-density screen) on the competitive interactions between seedlings of one liana (Byttneria grandifolia) and three tree species (two shade-tolerant trees,Litsea dilleniifoliaandPometia tomentosa, and one light-demanding tree,Bauhinia variegata) and to evaluate the contribution of both above- and below-ground competition. Trees were grown in four competition treatments with the liana: no competition, root competition, shoot competition and root and shoot competition. Light strongly affected leaf photosynthetic capacity (light-saturated photosynthetic rate,Pn), growth and most morphological traits of the tree species. Liana-induced competition resulted in reducedPn, total leaf areas and relative growth rates (RGR) of the three tree species. The relative importance of above- and below-ground competition differed between the two light levels. In low light, RGR of the three tree species was reduced more strongly by shoot competition (23.1–28.7% reduction) than by root competition (5.3–26.4%). In high light, in contrast, root competition rather than shoot competition greatly reduced RGR. Liana competition affected most morphological traits (except for specific leaf area and leaf area ratio ofLitseaandPometia), and differentially altered patterns of biomass allocation in the tree seedlings. These findings suggest that competition from liana seedlings can greatly suppress growth in tree seedlings of both light-demanding and shade-tolerant species and those effects differ with competition type (below- and above-ground) and with irradiance.

scholarly journals Urbanization pressures alter tree rhizosphere microbiomes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Carl L. Rosier ◽  
Shawn W. Polson ◽  
Vincent D’Amico ◽  
Jinjun Kan ◽  
Tara L. E. Trammell
Keyword(s):  
Organic Matter ◽  
Relative Abundance ◽  
Tree Species ◽  
High Throughput Sequencing ◽  
Regional Climate ◽  
Keystone Species ◽  
Fagus Grandifolia ◽  
Yellow Poplar ◽  
Individual Tree ◽  
Structural Formation

AbstractThe soil microbial community (SMC) provides critical ecosystem services including organic matter decomposition, soil structural formation, and nutrient cycling. Studies suggest plants, specifically trees, act as soil keystone species controlling SMC structure via multiple mechanisms (e.g., litter chemistry, root exudates, and canopy alteration of precipitation). Tree influence on SMC is shaped by local/regional climate effects on forested environments and the connection of forests to surrounding landscapes (e.g., urbanization). Urban soils offer an ideal analog to assess the influence of environmental conditions versus plant species-specific controls on SMC. We used next generation high throughput sequencing to characterize the SMC of specific tree species (Fagus grandifolia [beech] vs Liriodendron tulipifera [yellow poplar]) across an urban–rural gradient. Results indicate SMC dissimilarity within rural forests suggests the SMC is unique to individual tree species. However, greater urbanization pressure increased SMC similarity between tree species. Relative abundance, species richness, and evenness suggest that increases in similarity within urban forests is not the result of biodiversity loss, but rather due to greater overlap of shared taxa. Evaluation of soil chemistry across the rural–urban gradient indicate pH, Ca+, and organic matter are largely responsible for driving relative abundance of specific SMC members.

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