Shrub traits of forest and shrubland reveal different growth strategies

Shrub plants play important roles in both forest and shrubland ecosystems. Analyzing the differences of functional traits of shrubs grown in understory of forest communities and in various shrublands can explore the adaptation strategies of shrubs in different habitats. Nine functional traits of leaf and twig collected from 20 dominant shrub species in 24 plots distributed in three habitats: forest shrub layer, secondary shrubland and primary shrubland, in Beishan Mountain of Jinhua, Zhejiang Province, eastern China, were measured. The overall differences, inter- and intra-specific variations and the differences in various life forms of shrub traits in three different habitats were statistically analyzed. Results show that: 1) There are differences of nine plant traits for shrubs grown in three different habitats. The understory shrubs have larger leaf area (LA) and specific leaf area (SLA), smaller leaf dry matter content (LDMC), leaf tissue density (LTD) and twig tissue density (TTD), while shrubs in secondary shrubland have larger leaf thickness (LT) and LTD, smaller SLA and twig dry matter content (TDMC) compared with shrubs from the primary shrubland. 2) The intraspecific variation coefficients of SLA, twig diameter (TD), TTD, and TDMC in understory shrubs are the largest, while the interspecific variation coefficients of SLA, LDMC, TDMC, and TTD in ​​secondary shrubland are the smallest. 3) Among different life forms, the understory evergreen shrubs have significant higher LT, LTD, and LDMC than deciduous shrubs, while deciduous shrubs have significant higher SLA than evergreen shrubs. The differences of LT and SLA between evergreen and deciduous shrubs of primary shrubland are the same as those of understory shrubs, but the differences of LTD and LDMC between evergreen and deciduous shrubs have the opposite trend. 4) The main source affecting shrub traits is species, along with an explanation ratio from 38.01% to 78.92%. The second source is habitat. In short, compared to shrubs from shrublands, understory shrubs in forest communities form a series of trait combinations that are larger LA and SLA, smaller LTD, TTD, and LDMC to adapt to the understory environment with less light and stronger competition. Secondary shrubland, compared to the primary shrubland, has a series of shrub trait combinations that are larger LT, LTD and TD, smaller LA, SLA, TDMC and twig bark thickness (TBT) to store more nutrients.