Volume is an important attribute used in many forest management decisions.Data from 83 fixed-area plots located in central New Brunswick,Canada,are used to examine how different measures of stand-level diameter and he...Volume is an important attribute used in many forest management decisions.Data from 83 fixed-area plots located in central New Brunswick,Canada,are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer's(1967)volume equation.When density was included in the models(Volume=f(Diameter,Height,Density))choice of diameter measure was more important than choice of height measure.When density was not included(Volume=f(Diameter,Height)),the opposite was true.For models with density included,moment-based estimators of stand diameter and height performed better than all other measures.For models without density,largest tree estimators of stand diameter and height performed better than other measures.The overall best equation used quadratic mean diameter,Lorey's height,and density(root mean square error=5.26 m^3·ha^(-1);1.9%relative error).The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha(root mean square error=32.08 m^(3)·ha^(-1);11.8%relative error).The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.展开更多
Aims Sorghum halepense is a perennial invasive weed causing great harm worldwide,including some regions on Hainan island.In this study,we compared the performance between plants from outbreaking(dense stands covering ...Aims Sorghum halepense is a perennial invasive weed causing great harm worldwide,including some regions on Hainan island.In this study,we compared the performance between plants from outbreaking(dense stands covering large areas)and those from non-outbreaking(less dense stands covering smaller areas)populations.We also tested the hypothesis that plants with greater intraspecific competitive ability will have a lower stand biomass when grown under high-density conditions.Methods We grew plants of S.halepense individually,with an intraspecific competitor,with two interspecific competitors and with three or six plants from the same population per pot,and tested whether outbreaking and non-outbreaking populations differed in their performance.We also tested whether stand biomass(i.e.total biomass when three or six plants were grown together)was related to total biomass of individuals grown alone,and intra-or interspecific competitive ability.Important Findings Outbreaking and non-outbreaking populations of S.halepense differed in their biomass when individuals were grown alone,but not when grown in competition or when three or six plants from the same population were grown together.Across populations,biomass of individuals grown alone was negatively correlated with intra-and interspecific competitive ability,indicating that there is a trade-off between individual growth and competitive ability.Stand-level biomass was not related to total biomass of individuals grown alone,and intra-or interspecific competitive ability,indicating that low biomass when grown alone and high competitive ability may not reduce the performance of S.halepense when grown in dense monocultural stands.展开更多
基金the Natural Sciences and Engineering Research Council of Canada(Discovery Grant RGPIN-2023-05879)the New Brunswick Innovation Foundation(Emerging Projects Grant EP-0000000033)。
文摘Volume is an important attribute used in many forest management decisions.Data from 83 fixed-area plots located in central New Brunswick,Canada,are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer's(1967)volume equation.When density was included in the models(Volume=f(Diameter,Height,Density))choice of diameter measure was more important than choice of height measure.When density was not included(Volume=f(Diameter,Height)),the opposite was true.For models with density included,moment-based estimators of stand diameter and height performed better than all other measures.For models without density,largest tree estimators of stand diameter and height performed better than other measures.The overall best equation used quadratic mean diameter,Lorey's height,and density(root mean square error=5.26 m^3·ha^(-1);1.9%relative error).The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha(root mean square error=32.08 m^(3)·ha^(-1);11.8%relative error).The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.
基金This work was funded by the Project for High-level Talents of Basic and Applied Basic Research(Natural Science)in Hainan(2019RC280)the Key Research and Development Project of Hainan(ZDYF2019055)the Central Public-interest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences(630042019014 and 1630042017017).
文摘Aims Sorghum halepense is a perennial invasive weed causing great harm worldwide,including some regions on Hainan island.In this study,we compared the performance between plants from outbreaking(dense stands covering large areas)and those from non-outbreaking(less dense stands covering smaller areas)populations.We also tested the hypothesis that plants with greater intraspecific competitive ability will have a lower stand biomass when grown under high-density conditions.Methods We grew plants of S.halepense individually,with an intraspecific competitor,with two interspecific competitors and with three or six plants from the same population per pot,and tested whether outbreaking and non-outbreaking populations differed in their performance.We also tested whether stand biomass(i.e.total biomass when three or six plants were grown together)was related to total biomass of individuals grown alone,and intra-or interspecific competitive ability.Important Findings Outbreaking and non-outbreaking populations of S.halepense differed in their biomass when individuals were grown alone,but not when grown in competition or when three or six plants from the same population were grown together.Across populations,biomass of individuals grown alone was negatively correlated with intra-and interspecific competitive ability,indicating that there is a trade-off between individual growth and competitive ability.Stand-level biomass was not related to total biomass of individuals grown alone,and intra-or interspecific competitive ability,indicating that low biomass when grown alone and high competitive ability may not reduce the performance of S.halepense when grown in dense monocultural stands.
