Anatomical traits associated with absorption and mycorrhizal colonization are linked to root branch order in twenty-three Chinese temperate tree species.
* Different portions of tree root systems play distinct functional roles, yet precisely how to distinguish roots of different functions within the branching fine-root system is unclear. * Here, anatomy and mycorrhizal colonization was examined by branch order in 23 Chinese temperate tree species of both angiosperms and gymnosperms forming ectomycorrhizal and arbuscular-mycorrhizal associations. * Different branch orders showed marked differences in anatomy. First-order roots exhibited primary development with an intact cortex, a high mycorrhizal colonization rate and a low stele proportion, thus serving absorptive functions. Second and third orders had both primary and secondary development. Fourth and higher orders showed mostly secondary development with no cortex or mycorrhizal colonization, and thus have limited role in absorption. Based on anatomical traits, it was estimated that c. 75% of the fine-root length was absorptive, and 68% was mycorrhizal, averaged across species. * These results showed that: order predicted differences in root anatomy in a relatively consistent manner across species; anatomical traits associated with absorption and mycorrhizal colonization occurred mainly in the first three orders; the single diameter class approach may have overestimated absorptive root length by 25% in temperate forests.
Guo
Dali
D
Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.|Shenzhen Graduate School, Peking University, Shenzhen 518055, China.
Xia
Mengxue
M
Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Wei
Xing
X
School of Forestry, Northeast Forestry University, Harbin 150040, China.
Chang
Wenjing
W
Shenzhen Graduate School, Peking University, Shenzhen 518055, China.
Liu
Ying
Y
School of Forestry, Northeast Forestry University, Harbin 150040, China.
Wang
Zhengquan
Z
School of Forestry, Northeast Forestry University, Harbin 150040, China.
D000042:Absorption / Q000502:physiology*; D002681:China; D032462:Cycadopsida / Q000033:anatomy & histology / Q000378:metabolism / Q000382:microbiology; D017753:Ecosystem; D005502:Food; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000378:metabolism / Q000382:microbiology; D038821:Mycorrhizae / Q000254:growth & development* / Q000502:physiology; D018517:Plant Roots / Q000033:anatomy & histology* / Q000254:growth & development / Q000378:metabolism; D014197:Trees / Q000033:anatomy & histology* / Q000378:metabolism / Q000382:microbiology