Suchergebnisse

We quantified biomass and nutrient accumulation of Acacia dealbata Link and Eucalyptus globulus Labill. planted at stem densities of 5000 and 15000 ha(-1) in a bioenergy plantation in Chile. We tested the hypotheses that species and stocking will not affect biomass or nutrient accumulation. Species and stocking did not affect biomass accumulation after five years; however, species and stocking did influence nutrient mass. A. dealbata had higher nitrogen mass than E. globulus for total (397 kg ha(-1) more, i.e., 126% higher), foliage (188 kg ha(-1), 218%), branch (55 kg ha(-1), 95%), stem (120 kg ha(-1), 86%), and root (34 kg ha (-1), 109%) components, likely because A. dealbata fixes nitrogen. A. dealbata had lower calcium mass than E. globulus for branch (111 kg ha(-1), 60%) and stem (69 kg ha(-1), 39%) components. Root nitrogen and phosphorus masses and foliage, branch and root boron masses were significantly lower with a stocking density of 5000 ha(-1). Low stocking produced the same amount of total biomass as high stocking for both species and would be less expensive to plant. A. dealbata had higher nitrogen mass and likely increased soil nitrogen. E. globulus had high calcium mass in the stem and branches; off-site losses could be mitigated with stem-only harvests and debarking of stems in the field. Given the rainfall patterns and water availability constraints in Chile, additional criteria including water use efficiency would be required to determine the best species for bioenergy plantations in Chile. (C) 2017 Elsevier Ltd. All rights reserved. ; Department of Forest Resources and Environmental Conservation at Virginia Polytechnic Institute and State University; Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepcion; Department of Forestry and Environmental Resources at North Carolina State University; Virginia Agricultural Experiment Station; McIntire-Stennis Program of the National Institute of Food and Agriculture, United States Department of Agriculture; Chilean National Commission for Scientific and Technological Research; FONDECYTComision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [1140482] ; We gratefully acknowledge the support provided by the Forest Productivity Cooperative and especially Masisa S.A. for their role in providing the study site. We appreciate the support of the Department of Forest Resources and Environmental Conservation at Virginia Polytechnic Institute and State University, the Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepcion and the Department of Forestry and Environmental Resources at North Carolina State University. Funding for this work was provided in part by the Virginia Agricultural Experiment Station and the McIntire-Stennis Program of the National Institute of Food and Agriculture, United States Department of Agriculture. This work was supported by the Chilean National Commission for Scientific and Technological Research with FONDECYT Project Grant #1140482. We thank all those who helped complete the field work and to process the biomass samples especially Leonardo Munoz, Juan Espinoza, Yuri Burgos, Marco Yanez, Viviana Munoz and Pablo Mena. The use of trade names in this paper does not imply endorsement by the associated agencies of the products named, nor criticism of similar ones not mentioned. ; Public domain authored by a U.S. government employee

Short rotation Eucalyptus plantations offer great potential for increasing wood-fiber production in the southern United States. Eucalyptus plantations can be highly productive (>35 m(3) ha(-1) year but they may use more water than intensively managed pine (primarily Pinus taeda L) plantations. This has raised concern about how expansion of Eucalyptus plantations will affect water resources. We compared tree water use, stem growth, and WUE (kg wood per m(3) water transpired) in adjacent nine-year-old Eucalyptus benthamii and P. taeda plantations with similar stand density and leaf area. Sap flux (F-d, g cm(-2) s(-1)) was measured continuously over one year using thermal dissipation probes. Stem biomass, stem growth, tree water use (E-t, L day(-1)), canopy transpiration per unit leaf area (E-1, mmol m(-2) s(-1)), and canopy stomatal conductance (G(s), mmol m(2) s(-1)) were quantified. Eucalyptus had higher daily Fd (196.6 g cm(-2) day(-1)) and mean daily E-t (24.6 L day(-1)) than pine (105.8 g cm(-2) day(-1), 15.2 L day(-1)). Eucalyptus exhibited a seasonally bimodal pattern in daily E-t that did not occur in pine. Monthly E-t was23-51% higher in Eucalyptus and differences between species were greatest in the spring and fall. Annual E-t was 32% higher in Eucalyptus (9.13 m(3) H2O year(-1)) than pine (5.79 m(3) H2O year(-1)). Annual stem biomass increment was greater in Eucalyptus (Eucalyptus: 22.9; pine: 11.8 kg tree(-1) year(-1)), and Eucalyptus had greater WUE (Eucalyptus: 2.86; pine 1.72 kg biomass m(-3) H2O year(-1)). Pine exhibited a lower seasonal minimum and higher seasonal maximum leaf area index (LAI). At low LAI, there was no significant difference between species in E-l or G(s); however, at maximum LAI, pine E-l and G(s) were 46 and 43%, respectively of rates observed in Eucalyptus. The species differed in G(5) response to vapor pressure deficit (D). At a similar reference G(s) (G(s),(ref) at D =1 kPa), pine exhibited greater stomatal sensitivity to D. These results suggest that (1) Eucalyptus trees had higher sap flux and total water use than pine, (2) Eucalyptus had greater stem growth and WUE, and (3) species differences in water use were driven primarily by differences in E-l and G(s). Published by Elsevier B.V. ; Public domain authored by a U.S. government employee

We examined crown architecture and within crown leaf area distribution effects on Pinus taeda L. growth in North Carolina (NC), Virginia (VA), and Brazil (BR) to better understand why P. taeda can grow much better in Brazil than in the southeastern United States. The NC, VA, and BR sites were planted in 2009, 2009, and 2011, respectively. At all sites, we planted the same two genetic entries at 618, 1236, and 1854 trees ha(-1). In 2013, when trees were still open grown, the VA and NC sites had greater branch diameter (24%), branch number (14%), live crown length (44%), foliage mass (82%), and branch mass (91%), than the BR site. However, in 2017, after crown closure and when there was no significant difference in tree size, site did not significantly affect these crown variables. In 2013, site significantly affected absolute leaf area distribution, likely due to differences in live crown length and leaf area, such that there was more foliage at a given level in the crown at the VA and NC sites than at the BR site. In 2017, site was still a significant factor explaining leaf area distribution, although at this point, with crown closure and similar sized trees, there was more foliage at the BR site at a given level in the crown compared to the VA and NC sites. In 2013 and 2017, when including site, genetic entry, stand density, and leaf area distribution parameters as independent variables, site significantly affected individual tree growth efficiency, indicating that something other than leaf area distribution was influencing the site effect. Better BR P. taeda growth is likely due to a combination of factors, including leaf area distribution, crown architecture, and other factors that have been identified as influencing the site effect (heat sum), indicating that future work should include a modeling analysis to examine all known contributing factors. ; Public domain authored by a U.S. government employee

Previous work indicates that Pinus taeda L. grows faster and has a higher carrying capacity when grown outside its native range. We were interested in examining the hypotheses that growth, light use efficiency (volume growth and absorbed photosynthetically active radiation relationship, LUE) and volume growth per unit heat sum is the same for native and exotic plantations. To test these hypotheses, we installed a common garden experiment where the same six genetic entries of P. taeda (four clonal varieties, one open pollinated family and one control mass pollinated family) were planted at three densities (618, 1235, and 1853 stems ha(-1)) with three or four replications at three sites (Virginia (VA), and North Carolina (NC) in the United States and Parana State in Brazil (BR)). The VA and BR sites were outside the native range of P. taeda. After five years of growth, the BR site had larger trees and stand scale basal area and volume were increasing faster than the other sites. Site did not affect LUE but density and genetic entry did. The sites were at different latitudes but the average photosynthetically active radiation at the top of the canopy was similar for the years when all sites were operational, likely because the BR site receives more rain annually and the cloudiness associated with the rain may have reduced available light. We estimated an hourly heat sum where the daytime temperature was between 5 and 38 degrees C, hours where vapor pressure deficit exceeded 1.5 kPa and days following nights where nighttime temperatures were less than 0 degrees C were excluded. Site was significant for the cumulative volume and heat sum relationship, for a given level of cumulative degree hours the sites ranked BR > VA > NC in cumulative volume. The different growth per unit of degree hours for each site indicated that something other than the heat sum was causing the observed difference in growth. Other factors including respiration and extreme climatic conditions may contribute to growth differences per unit degree hour and including these differences in the analysis would require a more detailed modeling effort to examine. The sites used in this study are ideally suited to continue testing additional hypotheses to explain the different growth between native and exotic P. taeda plantations because they have the same genotypes at all sites and consequently eliminate differences in genetics as a potential explanation for observed growth differences. ; National Science Foundation Center for Advanced Forest Systems; Department of Forest Resources and Environmental Conservation at Virginia Polytechnic Institute and State University; Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepcion; Department of Forestry and Environmental Resources at North Carolina State University; Federal University of Santa Catarina; Virginia Agricultural Experiment Station; McIntire-Stennis Program of the National Institute of Food and Agriculture, U.S. Department of Agriculture; Forest Productivity Cooperative ; We appreciate support from the Forest Productivity Cooperative and members for their role in the establishment and management of the trials central to this publication. We gratefully acknowledge the support provided by the National Science Foundation Center for Advanced Forest Systems, the Department of Forest Resources and Environmental Conservation at Virginia Polytechnic Institute and State University, the Departamento de Silvicultura, Facultad de Ciencias Forestales, Universidad de Concepcion, the Department of Forestry and Environmental Resources at North Carolina State University and the Federal University of Santa Catarina. Funding for this work was provided in part by the Virginia Agricultural Experiment Station and the McIntire-Stennis Program of the National Institute of Food and Agriculture, U.S. Department of Agriculture. The use of trade names in this paper does not imply endorsement by the associated agencies of the products named nor criticism of similar ones not mentioned. We are grateful for Arborgen for supplying the genetic material, for the assistance of K. Peer and C. Sawyer at The Reynolds Homestead, H.C. Rohr at the North Carolina Forest Service's Bladen Lakes State Forest and the personnel at Valor Florestal in the installation and ongoing maintenance of the study sites. ; Public domain authored by a U.S. government employee