DOI: 10.5061/dryad.bvq83bk8f
title: Joint control of plant ecological strategy by climate, regeneration mode, and ontogeny in Northeastern Chinese forests

description: Research on how plant ecological strategies (competitive, stress-tolerant,
 or ruderal) vary within species may improve our understanding of plant and
 community responses to climate warming and also successional changes. With
 increasing temperature, the importance of ruderal (R) and stress-tolerance
 (S) components is hypothesized to decrease, while the strength of the
 competitive (C) component should increase. Offshoots and younger plants
 are predicted to have greater R and smaller S components. Leaf area, leaf
 dry matter content, and specific leaf area were measured for 1,344 forest
 plants belonging to 134 species in Northeastern China, and C, R, and S
 scores calculated for each. Linear mixed effect models were used to assess
 how these indicators differed among study sites (n = 2), regeneration
 types, ontogenetic stages, and plant life forms. The two study sites have
 an average annual temperature difference of 0.675°C, simulating a
 temperature increase of 0.630°C due to climate warming. Higher
 temperatures reduce low-temperature stress and frost damage, which may
 explain the observed decrease in R and S scores; at the same time, plant
 competitive ability increased, as manifested by higher C scores. This
 effect was most pronounced for herbs, but nearly negligible as compared to
 the effect of regeneration type for trees and of ontogeny for woody
 species. Resprouting trees and younger woody plants had higher R scores
 and lower S scores, a sign of adaptation to high disturbance. A small
 increase in mean annual temperature led to shifts in CSR strategy
 components for herbaceous species, without altering the vegetation type or
 community composition. Offshoots and younger plants had higher R and lower
 S scores, shedding light on similar changes in the ecological strategies
 of tree communities during secondary succession, such as the transition of
 Quercus mongolica coppices to forest, and age-related changes in Populus
 davidiana-Betula platyphylla forests.
description: The leaves of all
 tree, shrub, and herbaceous species (A total of 134 species, including 25
 trees, 28 shrubs, and 81 herbs, 123 species in FL and 120 in LS) were
 extensively sampled according to tree regeneration types and woody plant
 ontogenetic stages. For each type, the goal was to obtain at least six
 replicas per site; however, for a few rare plant species, only three to
 five replicates were possible. Very few plant species were too rare to be
 sampled sufficiently. In order to ensure enough regeneration samples
 (<i>i.e.</i>, at
 least six replicates of each regeneration type per site) and to accurately
 identify resprouting versus seed regeneration, only five tree species were
 sampled (<i>A.
 sibirica</i>, <i>Acer mono</i>,
 <i>B.
 platyphylla</i>, <i>Padus
 racemose</i>, and <i>Q.
 mongolica</i>); additionally, sampled individuals
 including seedling and resprouting were mature trees that had flowered and
 fruited. For trees, four ontogenetic stages were established: seedling,
 sapling, young adult, and adult. Seedlings were defined for coniferous
 trees as individuals with height &lt; 30 cm and for broad-leaved
 species as individuals with height &lt; 50 cm. Coniferous saplings had
 heights &gt; 30 cm and broad-leaved saplings heights &gt; 50 cm,
 in addition to a diameter at breast height (DBH) &lt; 5 cm. Young
 adult trees were those that had just entered the reproductive stage, and
 generally had DBH ranging from 5 to 15 cm. Finally, adult trees were
 reproductively mature and had DBH &gt; 30 cm. For shrubs, two
 ontogenetic stages were recognized: saplings and adults. Shrub saplings
 were structurally simple, unbranched individuals of height &gt; 50 cm
 that showed an absence of reproductive organs, while adults had entered
 the reproductive stage. The leaf area
 (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) were
 determined according to Pérez-Harguindeguy et al. (2013). Leaf
 sampling took place from July 19 to 23, 2019 in LS, and from July 25 to
 28, 2019 in FL; at this time, the leaves had fully expanded and reached
 maturity. Three to five unshaded directions were selected in the canopy
 for sampling, and vigorously growing branches were then collected for leaf
 extraction. Tall trees were sampled by professional climbers (Figure S1).
 Three to thirty undamaged, fully expanded leaves were measured per sampled
 individual. The C, S, and R scores for each individual were calculated
 using “StrateFy” (Pierce et al., 2017).
description: Access to the data is embargoed for a period up to a year after
 publication. After, our data will be freely available for the scientific
 community, upon citation of this manuscript.