Evaluating Long-Term Seedling Growth across Densities Using Nelder Plots and the Forest Vegetation Simulator (FVS) in the Black Hills, South Dakota, USA

2021 ◽  
Author(s):  
Wade T Tinkham ◽  
Mike A Battaglia ◽  
Chad M Hoffman
Keyword(s):  
Seedling Growth ◽  
Tree Growth ◽  
Forest Growth ◽  
Forest Vegetation ◽  
Planting Density ◽  
Harvest Scheduling ◽  
Sustainable Harvest ◽  
Forest Vegetation Simulator ◽  
Small Tree ◽  
Fuel Treatment

Abstract Small-tree development affects future stand dynamics and dictates many ecological processes within a site. Accurately representing this critical component of stand development is important for evaluating treatment alternatives from fuel hazard reduction to harvest scheduling. As with all forest growth, competition with other vegetation is known to regulate small-tree growth dynamics. This study uses three Nelder plots with 45 years of ponderosa pine growth to understand competition effects on seedling growth and evaluate the Forest Vegetation Simulator (FVS) Central Rockies (CR) variant’s ability to represent these dynamics. Removal of herbaceous competition before planting increased tree diameters by 50–135% and height by 35–75% across a planting density gradient at age 12. However, by age 45, the effect of herbaceous competition on tree size was no longer evident. Instead, trees at the lowest planting density had diameters 2.5–3 times larger than the most densely grown trees. Forest Vegetation Simulator (FVS) simulations underpredicted diameter at breast height (dbh) by 35–50% and 0–35% for 12 and 45-year-old trees, respectively. There was an underprediction bias of 15–20% for heights at age 12 and overpredictions of 5–10% at age 45. Continuous underprediction of dbh will affect the reliability of modeled fuel treatment longevity and sustainable harvest scheduling. Study Implications: Management and modeling of small-tree growth can affect decision-making for a range of activities, from assessing fuel treatment effectiveness to sustainable harvest scheduling. Effective small-tree density management can increase tree diameters at age 45 by 2.5–3 times the diameter of unthinned sites. FVS-CR underpredicted age 12 heights by 0–45% and age 45 diameters by 0–35% as a function of planting density, suggesting that the model fails to capture the intensity or timing of density-induced competition. These underpredictions will inflate the length of time fuel treatments remain effective and decrease projected sustainable harvest levels supported by responsible management.

scholarly journals Incorporation of Genetic Gain into Growth Projections of Douglas-Fir Using ORGANON and the Forest Vegetation Simulator

2010 ◽  
Vol 25 (2) ◽  
pp. 55-61 ◽  
Author(s):  
Peter J. Gould ◽  
David D. Marshall
Keyword(s):  
Pacific Northwest ◽  
Genetic Gain ◽  
Growth Models ◽  
Regional Growth ◽  
Site Index ◽  
Douglas Fir ◽  
Forest Vegetation ◽  
Planting Density ◽  
Forest Vegetation Simulator ◽  
Stand Management

Abstract Growth models for coast Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) are generally based on measurements of stands that are genetically unimproved (or woods-run); therefore, they cannot be expected to accurately project the development of stands that originate from improved seedlots. In this report, we demonstrate how early expected gain and genetic-gain multipliers can be incorporated into growth projection, and we also summarize projected volume gains and other aspects of stand development under different levels of genetic gain, site productivity, and initial planting density. Representative tree lists that included three levels of productivity (site index = 100, 125, and 150 ft; base = 50 years)and three initial planting densities (302, 435, and 602 trees/ac) were projected from ages 10 to 60 years under three scenarios using two regional growth models (Stand Management Cooperative version of ORGANON and the Pacific Northwest variant of the Forest Vegetation Simulator). The two models projected similar percentage volume gains for improved seedlots. Seedlots with a genetic worth (GW) of 5% for height and diameter growth were projected to have volume gains of 3.3–5.8% over woods-run stands at 40 years and 2.1–3.2% at 60 years. Volume gains were projected to approximately double when GW was increased from 5 to 10%.

Accuracy and equivalence testing of crown ratio models and assessment of their impact on diameter growth and basal area increment predictions of two variants of the Forest Vegetation Simulator

2009 ◽  
Vol 39 (3) ◽  
pp. 655-665 ◽  
Author(s):  
Laura P. Leites ◽  
Andrew P. Robinson ◽  
Nicholas L. Crookston
Keyword(s):  
Predictor Variable ◽  
Basal Area ◽  
Forest Growth ◽  
Forest Vegetation ◽  
Basal Area Increment ◽  
Growth And Yield ◽  
Estimation Accuracy ◽  
Diameter Growth ◽  
Forest Vegetation Simulator ◽  
South Central

Diameter growth (DG) equations in many existing forest growth and yield models use tree crown ratio (CR) as a predictor variable. Where CR is not measured, it is estimated from other measured variables. We evaluated CR estimation accuracy for the models in two Forest Vegetation Simulator variants: the exponential and the logistic CR models used in the North Idaho (NI) variant, and the Weibull model used in the South Central Oregon and Northeast California (SO) variant. We also assessed the effects of using measured (CRm) versus predicted (CRp) crown ratio for predicting 10 year DG and 30 year basal area increment (BAI). Evaluation criteria included equivalence tests, bias, root mean square error, and Spearman’s coefficient of rank correlation. Inventory data from the Winema and the Colville National Forests were used. Results showed that the NI variant models overpredicted CR when CRm was below 40% and underpredicted CR when it was above 60%, whereas the SO variant model overpredicted CR when CRm was smaller than 60%. Differences between CRm and CRp were positively correlated with differences in DG predictions. Using CRm versus CRp resulted in 30 year BAI absolute percent differences of 10% or less for more than 50% of the plots.

Tree growth across the Nepal Himalaya during the last four centuries

2017 ◽  
Vol 41 (4) ◽  
pp. 478-495 ◽  
Author(s):  
UK Thapa ◽  
S St. George ◽  
DK Kharal ◽  
NP Gaire
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Environmental Changes ◽  
Ring Width ◽  
High Elevation ◽  
Forest Growth ◽  
Tree Ring Width ◽  
Early 19Th Century ◽  
Tree Ring Data ◽  
Instrumental Records

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.

scholarly journals A 406-year non-growing-season precipitation reconstruction in the southeastern Tibetan Plateau

2021 ◽  
Vol 17 (6) ◽  
pp. 2381-2392
Author(s):  
Maierdang Keyimu ◽  
Zongshan Li ◽  
Bojie Fu ◽  
Guohua Liu ◽  
Fanjiang Zeng ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Tree Growth ◽  
Ring Width ◽  
Growing Season ◽  
Climatic Conditions ◽  
Forest Growth ◽  
Drought Severity ◽  
Precipitation Reconstruction ◽  
Southeastern Tibetan Plateau

Abstract. Trees record climatic conditions during their growth, and tree rings serve as proxy to reveal the features of the historical climate of a region. In this study, we collected tree-ring cores of hemlock forest (Tsuga forrestii) from the northwestern Yunnan area of the southeastern Tibetan Plateau (SETP) and created a residual tree-ring width (TRW) chronology. An analysis of the relationship between tree growth and climate revealed that precipitation during the non-growing season (NGS) (from November of the previous year to February of the current year) was the most important constraining factor on the radial tree growth of hemlock forests in this region. In addition, the influence of NGS precipitation on radial tree growth was relatively uniform over time (1956–2005). Accordingly, we reconstructed the NGS precipitation over the period spanning from 1600–2005. The reconstruction accounted for 28.5 % of the actual variance during the common period of 1956–2005. Based on the reconstruction, NGS was extremely dry during the years 1656, 1694, 1703, 1736, 1897, 1907, 1943, 1982 and 1999. In contrast, the NGS was extremely wet during the years 1627, 1638, 1654, 1832, 1834–1835 and 1992. Similar variations of the NGS precipitation reconstruction series and Palmer Drought Severity Index (PDSI) reconstructions of early growing season from surrounding regions indicated the reliability of the present reconstruction. A comparison of the reconstruction with Climate Research Unit (CRU) gridded data revealed that our reconstruction was representative of the NGS precipitation variability of a large region in the SETP. Our study provides the first historical NGS precipitation reconstruction in the SETP which enriches the understanding of the long-term climate variability of this region. The NGS precipitation showed slightly increasing trend during the last decade which might accelerate regional hemlock forest growth.

The Growth Charactersitics Study of Introduction Fast-Growing Poplar at the Initial Stage of Afforestation

2013 ◽  
Vol 726-731 ◽  
pp. 4270-4273
Author(s):  
Pei Yong Lian ◽  
Jin Ye Liu ◽  
Lian Kuan Wang
Keyword(s):  
Tree Growth ◽  
Inner Mongolia ◽  
Planting Density ◽  
Seedling Height ◽  
Effect Analysis ◽  
Fast Growing ◽  
Forest Region ◽  
Initial Stage ◽  
Factor Effect

We have carried out three consecutive years of tree growth survey, and studied on afforestation technology, compatibility and high-yielding measures, we conducted two-factor effect analysis of different varieties and different density on seedling height and ground diameter in the annual introduction of fast-growing poplar. The results showed that the influence of different varieties of seedling height and ground diameter was extremely significant, and the influence of different density of seedling height and ground diameter was not significant basically. Based on the above results, it can be preliminarily determined the most suitable fast-growing poplar and planting density for Inner Mongolia Daxinganling Forest Region.

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