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Marked individual northern red oak seedlings were individually marked and mapped at 20 valleywide transects starting in summer 2011. This data set includes detailed seedling measures starting in summer 2014. The data were used to examine the impact of previous year seedling condition on whether the seedling survived in the next season. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
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Hubbard Brook Experimental Forest: Annual measurements on marked northern red oak seedlings, 2014-ongoing
Marked individual northern red oak seedlings were individually marked and mapped at 20 valleywide transects starting in summer 2011. This data set includes detailed seedling measures starting in summer 2014. The data were used to examine the impact of previous year seedling condition on whether the seedling survived in the next season.
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- PAR ID:
- 10492181
- Publisher / Repository:
- Environmental Data Initiative
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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This data set was built from a larger data set of marked northern red oak seedlings surveyed from 2011-2023. In this data set, only seedlings marked in their year of germination with full environmental and seedlings measures were kept (N = 937). The data set was built for an accelerated failure time model of seedling survival that found year of germination, seedling density, shrub cover and elevation to have the largest effect on survival time. The status of the seedling acorn (attached or missing) was also important. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
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Abstract Global change has created less stable forest systems and given urgency to understanding limitations to the establishment of tree seedlings beyond current range boundaries. We quantified trends in 13 years of annual northern red oak (QURU) seedling survival data for 1733 marked individuals at a local species distribution boundary within the northern hardwood forest in New Hampshire, USA. Over the study period, the median distance of seedlings into the valley did not change, although there was a net gain of 89 plots (5 m2) occupied. For a subset of seedlings that were marked in their year of birth (N = 937), we examined relationships among terrain, vegetation community, and initial individual seedling traits, and evaluated their effects on time to seedling mortality using a parametric accelerated failure time model. The year of seedling germination had the largest effect on survival with increasing mortality rates for seedlings from more recent cohorts. Seedlings had longer survival times where oak seedling densities were lower, shrub cover was higher, and when the acorn remained attached. Additionally, survival time was increased in higher elevation plots, which were also located further into the valley. Interannual seedling survival (N = 1580) was strongly impacted by seedling condition in the previous year, particularly leaf number and amount of leaf damage. Most seedling deaths occurred over winter, and seedlings failed to break bud the following spring. Interannual variation in seasonal climate, particularly deep, heavy snowpack in 2019 followed by drought conditions in 2020, coincided with recent elevated mortality. Overall, the median survival time of 3–4 years and the rapid turnover of the oak seedling population currently limit ability for expansion, although the net gain of occupied plots and increase in survival at higher elevation plots with lower QURU densities present some mechanisms that could promote expansion if the current suboptimal understory conditions shift to favor QURU.more » « less
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Marked seedlings. Our dataset includes 1463 marked individual oak seedlings in 535 5m2 plots over the 20 transects. Overall, oak seedlings occurred in a third of the searched plots. Most plots had only one seedling (236 plots) and only 3% (16 plots) of the plots had 10 or more seedlings, with a maximum density of 3.4 seedlings m2. Cohort years 2011, 2015, 2017 and 2022 had a greater influx of seedlings, and our oldest seedling is estimated to be 30 years or older. For seedlings where initial height was measured in their year of germination (i.e., in 2011 or later) mean initial seedling height was 14.8 cm (SD = 6.51 cm) and there was a small but significant decline in initial seedling height with time (-0.23 cm/year, F1,1298 = 19.97, p=<0.0001). The size of first year seedlings as measured by both initial height (F1,760 = 25.2, p<0.001) and leaf number (F1,752 = 11.1, p=0.009) increased on average with distance into the valley. The mean distance of oak seedlings into the valley has not increased over the course of the study and remains centered around 800m from the east entrance. Plot environment. Study transects encompassed a full range of topographic positions in the lower valley. Hemlock dominance ranged from absent (5 transects) to dominant (greater than 50% of trees; 3 transects). Tree basal area around the plots ranged from 18.8 – 43.5 m2 ha-1. Light transmission was universally low (all ≤13% TT). Light transmission (F1,5916 = 139.3; r2: 0.157, p<0.0001), hemlock dominance (F1,5916 = 2024; r2: 0.255, p<0.0001), and oak seedling density (F1,5916 = 73.9; r2: 0.126, p<0.0001) all decreased with distance further west into the valley. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
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{"Abstract":["The germination rate of creosote (Larrea tridentata) on the\n Sevilleta appears to be very low. During the early years of the LTER\n project it was attempted to quantify such germination through the\n use of seedling plots which were monitored on a bi-annual basis\n (spring and fall). During the period from 1989 through 1992 there\n were no creosote seedling that germinated on the monitoring plots.\n In 1999 a rather sizeable population of small seedlings was observed\n in one quite localized area in the vicinity of Five Points. This\n rather large number of individuals in one very limited area raised\n several questions:1. When did this small community of individuals\n germinate- the supposition is that they had all germinated at the\n same time.2. What conditions existed in this particular location\n which allowed such prolific germination when there was no indication\n of virtually any other germination in this vicinty.3. The most\n immediate question was whether these seedlings would survive through\n the impending La Nina winter, spring and summer as many of the\n individuals did not appear to be very "healthy." To help\n answer these questions it was decided to begin a "small"\n monitoring project. All of the individuals in this small area that\n appeared to be of the same age were marked with posts, located with\n GPS, measured (height) and photographed. This initial survey\n included 78 individuals. The population was resurveyed in August,\n 2000 and it was discovered that: 1. Many individuals were missed in\n the initial survey; 2. Most of the individuals (72 of 78) had\n survived the intervening 9 months; and 3. The average individual\n growth during this period was 1.4 cm. It is planned that this\n population will continue to be monitored (probably on an annual\n basis) to track survival and growth rate of these individuals. "]}more » « less
