An official website of the United States government
Tree plantations represent an important component of the global carbon (C) cycle and are expected to increase in prevalence during the 21st century. We examined how silvicultural approaches that optimize economic returns in loblolly pine (Pinus taeda L.) plantations affected the accumulation of C in pools of vegetation, detritus, and mineral soil up to 100 cm across the loblolly pine’s natural range in the southeastern United States. Comparisons of silvicultural treatments included competing vegetation or ‘weed’ control, fertilization, thinning, and varying intensities of silvicultural treatment for 106 experimental plantations and 322 plots. The average age of the sampled plantations was 17 years, and the C stored in vegetation (pine and understory) averaged 82.1 ± 3.0 (±std. error) Mg C ha−1, and 14.3 ± 0.6 Mg C ha−1 in detrital pools (soil organic layers, coarse-woody debris, and soil detritus). Mineral soil C (0–100 cm) averaged 79.8 ± 4.6 Mg C ha−1 across sites. For management effects, thinning reduced vegetation by 35.5 ± 1.2 Mg C ha−1 for all treatment combinations. Weed control and fertilization increased vegetation between 2.3 and 5.7 Mg C ha−1 across treatment combinations, with high intensity silvicultural applications producing greater vegetation C than low intensity (increase of 21.4 ± 1.7 Mg C ha−1). Detrital C pools were negatively affected by thinning where either fertilization or weed control were also applied, and were increased with management intensity. Mineral soil C did not respond to any silvicultural treatments. From these data, we constructed regression models that summarized the C accumulation in detritus and detritus + vegetation in response to independent variables commonly monitored by plantation managers (site index (SI), trees per hectare (TPH) and plantation age (AGE)). The C stored in detritus and vegetation increased on average with AGE and both models included SI and TPH. The detritus model explained less variance (adj. R2 = 0.29) than the detritus + vegetation model (adj. R2 = 0.87). A general recommendation for managers looking to maximize C storage would be to maintain a high TPH and increase SI, with SI manipulation having a greater relative effect. From the model, we predict that a plantation managed to achieve the average upper third SI (26.8) within our observations, and planted at 1500 TPH, could accumulate ~85 Mg C ha−1 by 12 years of age in detritus and vegetation, an amount greater than the region’s average mineral soil C pool. Notably, SI can be increased using both genetic and silviculture technologies.
more »
« less
This content will become publicly available on December 1, 2025
Growth trends of loblolly pine age five or less in relation to soil type and management intensity
We evaluated three objectives for loblolly pine (Pinus taeda L.) trees age five or less: 1) how height growth varies by soil type and silvicultural intensity, 2) the accuracy of predicted base-age 25 site index (SI25) using age one to five heights, and 3) if height dominance exhibited early in the rotation is maintained throughout the rotation. Data from 42 sites across the southeastern United States with an array of soil textures and management intensities (optimal, intensive, and operational) were used. Management intensity and soils significantly affected tree height. Coarse loamy soils were the most responsive to increasing management intensity. At age four, tree heights were greatest in the optimal group (4.63 m), followed by the intensive (4.31 m), and then the operational (3.06 m). Organic soils do not appear to respond to maximum management intensity. Predictability of SI25 was high especially starting at age four, with R2 values ranging from 0.27 for the age four intensive group to 0.78 for the age four operational group. The optimal group had the greatest slope with an expected increase of 2.61, 2.75, 1.88, and 1.78 m in site index per additional meter of height at ages two, three, four, or five, respectively. Data from six different study sites indicate, the tallest (class one) and smallest (class five) trees changed percentile class the least often over time. As early as age two, over 40 % of observations in classes one and five had zero changes in class through age 13. Young tree data were effective in predicting SI25, and height dominance appeared generally set early in the rotation.
more »
« less
- Award ID(s):
- 1916552
- PAR ID:
- 10579958
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Forest Ecology and Management
- Volume:
- 574
- Issue:
- C
- ISSN:
- 0378-1127
- Page Range / eLocation ID:
- 122355
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Druzhinina, Irina S. (Ed.)ABSTRACT Trees associating with different mycorrhizas often differ in their effects on litter decomposition, nutrient cycling, soil organic matter (SOM) dynamics, and plant-soil interactions. For example, due to differences between arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree leaf and root traits, ECM-associated soil has lower rates of C and N cycling and lower N availability than AM-associated soil. These observations suggest that many groups of nonmycorrhizal fungi should be affected by the mycorrhizal associations of dominant trees through controls on nutrient availability. To test this overarching hypothesis, we explored the influence of predominant forest mycorrhizal type and mineral N availability on soil fungal communities using next-generation amplicon sequencing. Soils from four temperate hardwood forests in southern Indiana, United States, were studied; three forests formed a natural gradient of mycorrhizal dominance (100% AM tree basal area to 100% ECM basal area), while the fourth forest contained a factorial experiment testing long-term N addition in both dominant mycorrhizal types. We found that overall fungal diversity, as well as the diversity and relative abundance of plant pathogenic and saprotrophic fungi, increased with greater AM tree dominance. Additionally, tree community mycorrhizal associations explained more variation in fungal community composition than abiotic variables, including soil depth, SOM content, nitrification rate, and mineral N availability. Our findings suggest that tree mycorrhizal associations may be good predictors of the diversity, composition, and functional potential of soil fungal communities in temperate hardwood forests. These observations help explain differing biogeochemistry and community dynamics found in forest stands dominated by differing mycorrhizal types. IMPORTANCE Our work explores how differing mycorrhizal associations of temperate hardwood trees (i.e., arbuscular [AM] versus ectomycorrhizal [ECM] associations) affect soil fungal communities by altering the diversity and relative abundance of saprotrophic and plant-pathogenic fungi along natural gradients of mycorrhizal dominance. Because temperate hardwood forests are predicted to become more AM dominant with climate change, studies examining soil communities along mycorrhizal gradients are necessary to understand how these global changes may alter future soil fungal communities and their functional potential. Ours, along with other recent studies, identify possible global trends in the frequency of specific fungal functional groups responsible for nutrient cycling and plant-soil interactions as they relate to mycorrhizal associations.more » « less
-
Abstract In savannas, partitioning of below‐ground resources by depth could facilitate tree–grass coexistence and shape vegetation responses to changing rainfall patterns. However, most studies assessing tree versus grass root‐niche partitioning have focused on one or two sites, limiting generalization about how rainfall and soil conditions influence the degree of rooting overlap across environmental gradients.We used two complementary stable isotope techniques to quantify variation (a) in water uptake depths and (b) in fine‐root biomass distributions among dominant trees and grasses at eight semi‐arid savanna sites in Kruger National Park, South Africa. Sites were located on contrasting soil textures (clayey basaltic soils vs. sandy granitic soils) and paired along a gradient of mean annual rainfall.Soil texture predicted variation in mean water uptake depths and fine‐root allocation. While grasses maintained roots close to the surface and consistently used shallow water, trees on sandy soils distributed roots more evenly across soil depths and used deeper soil water, resulting in greater divergence between tree and grass rooting on sandy soils. Mean annual rainfall predicted some variation among sites in tree water uptake depth, but had a weaker influence on fine‐root allocation.Synthesis. Savanna trees overlapped more with shallow‐rooted grasses on clayey soils and were more distinct in their use of deeper soil layers on sandy soils, consistent with expected differences in infiltration and percolation. These differences, which could allow trees to escape grass competition more effectively on sandy soils, may explain observed differences in tree densities and rates of woody encroachment with soil texture. Differences in the degree of root‐niche separation could also drive heterogeneous responses of savanna vegetation to predicted shifts in the frequency and intensity of rainfall.more » « less
-
Roberts, Scott (Ed.)Abstract On-the-ground sample-based forest inventory methods have been the standard practice for more than a century, however, remote sensing technologies such as airborne laser scanning (ALS) are providing wall-to-wall inventories based on individual tree measurements. In this study, we assess the accuracy of individual tree height, diameter, and volume derived from field-cruising measurements and three ALS data-derived methods in a 1.1 ha stand using direct measurements acquired on felled trees and log-scale volume measurements. Results show that although height derived from indirect conventional field measurements and ALS were statistically equivalent to felled tree height measurements, ALS measured heights had lower root mean square error (RMSE) and bias. Individual tree diameters modeled using a height-to-diameter-at-breast-height model derived from local forest inventory data and the software ForestView had moderate RMSE (8.3–8.5 cm) and bias (-3.0 – -0.3 cm). The ALS-based methods underdetected trees but accounted for 78%–91% of the field reference harvested merchantable volume and 71%–99% of the merchantable volume scaled at the mill. The results also illustrate challenges of using mill-scaled volume estimates as validation data and highlight the need for more research in this area. Overall, the results provide key insights to forest managers on accuracies associated with conventional field-derived and ALS-derived individual tree inventories. Study Implications: Forest inventory data provide critical information for operational decisions and forest product supply chain planning. Traditionally, forest inventories have used field sampling of stand conditions, which is time-intensive and cost-prohibitive to conduct at large spatial scales. Remote sensing technologies such as airborne laser scanning (ALS) provide wall-to-wall inventories based on individual tree measurements. This study advances our understanding of the accuracy of conventional field-derived and ALS-derived individual tree inventories by evaluating these inventories with felled tree and log scaling data. The results provide key insights to forest managers on errors associated with conventional field and ALS-derived individual tree measurements.more » « less
-
Overview: These data sets are the culmination of a five-year community science project done in collaboration with the Society for Protection of NH Forests. Co-authors on the resulting paper were: Carrie Deegan, Sarah Thorne, Ana Suppé, Kimberly L. Colson and Wanda Rice. Funding was provided by: Engaged Research Grant from the Einhorn Center for Community Engagement at Cornell University 2019 - 2023; Public Engagement with Science Grant (NSF grant #1713204) subcontract from Hubbard Brook Research Foundation; USDA Climate Hub; NSF-REU supplement under the HBR LTER (NSF grant #1637685) in 2021 and 2022 and HBR LTER in 2023 (NSF grant #2224545 ). Undergraduate students who helped on the project: Katie Sims, Alex Ding, Esmée deCortie, Sage Wentzell-Brehme, Colin Craig, Linda Mahecha, Roxy Moore. Community volunteers who contributed to field data collection and project meetings: Paul Doscher, Dave Heuss, Kim Sharp, Chris Brown, Tim Kendrick, Dan Poor, Rickey Poor, and Blaine Kopp. The study was conducted in four mature forest stands with a notable sugar maple component owned and managed by the Society for Protection of New Hampshire Forests (Forest Society) and spanning most of the latitudinal gradient in the state. Plots were established in autumn of 2018. In general, 12 plot locations were established for each of the four forest stands. Plots are spatially-uniform and placed as close to a 100 m grid system as possible with the restriction that the plot had to include three canopy sugar maple trees. The plots are 0.05 hectares or 500 m2 in size measured in a 12.62 m radius circular plot. Marked_sdlg_site_EDI: This data set contains survival, leaf area and leaf damage for 1191 sugar maple seedlings at four sites in New Hampshire. The sugar maple seedlings were two years old at the time of marking in 2019 and were from the 2017 mast year. The study followed the seedlings on 12 plots per site for 5 years (2019-2023). The data file also contains plot and site variables for topography, soil chemistry and tree density and sugar maple dominance. Some of the main findings from the study were the importance of site, initial leaf area and leaf damage to seedling survival. Litter_coll_ForestSoc_2yr: Leaves and seeds were collected from half of the plots (N=6) per site using three collectors. Count and dry weight were obtained for the leaves and counts for any seeds. This data set contains the main autumn collection data for 2019 and 2020. The were 20 tree species included over the four sites. There was a pattern of greater productivity in the southern site (greatest number of leaves) and decreased productivity in the northern site (lowest dry mass of leaves). Seed production for sugar maple was higher in 2019. Sweep_ForestSoc: Sapling layers were generally open with only 281 saplings from all plots. Kauffmann had the densest and most diverse sapling layer. The saplings were only measured once in 2019. Tagged_trees_ForestSoc: The data set includes growth (4 year) and vigor data (every other year) for 1335 trees in four study sites in New Hampshire. The data set includes data for 16 tree species tagged in 2019 and assessed in 2021 and 2023. At all sites, sugar maple growth was slower than average tree growth and mortality for sugar maple was higher than the average tree. This data set does not include data for trees that died during the study and therefore do not have growth data (96 trees). Common_garden_sdlgs: This data set includes harvest data for 50 sugar maple seedlings grown in a common garden experiment with soil from the four study sites taken from two microsites: sugar maple dominated and dominated by other species. The experimental setup had two controls. One control was the live soil from the site where the seedlings were obtained (native soil control). A second control contained a mix of sugar maple soil from the four sites that had been sterilized (pathogen free control). The experiment did not demonstrate a microsite difference for seedling growth but rather sites differed with the most nutrient rich soil resulting in larger seedlings. Overall, the experiment did not support a significant role of soil pathogens in explaining seedling survival differences between sites. ACSA_samaras_2019: This data table gives counts and condition of the samaras collected at the four study sites in autumn 2019, which represented the largest seed year during the study time. This data is useful for comparing differences in pre-dispersal damage to the seeds and seed production across sites. 2020_germinant_counts: This data table gives counts of newly germinated sugar maple seedlings at the plots with collectors (odd numbered plots). Sites were visited 14-18 May 2020. These data are used for comparing initial seedling densities across sites and the number of seedlings compared to the number of seeds for those plots, which gives an idea of post-dispersal survival.more » « less
