Understorey plant community and light availability in conifer plantations and natural hardwood forests in Taiwan

Questions: What are the effects of replacing mixed species natural forests with Cryptomeria japonica plantations on understorey plant functional and species diversity? What is the role of the understorey light environment in determining understorey diversity and community in the two types of forest? Location: Subtropical northeast Taiwan. Methods: We examined light environments using hemispherical photography, and diversity and composition of understorey plants of a 35‐yr C. japonica plantation and an adjacent natural hardwood forest. Results: Understorey plant species richness was similar in the two forests, but the communities were different; only 18 of the 91 recorded understorey plant species occurred in both forests. Relative abundance of plants among different functional groups differed between the two forests. Relative numbers of shade‐tolerant and shade‐intolerant seedling individuals were also different between the two forest types with only one shade‐intolerant seedling in the plantation compared to 23 seedlings belonging to two species in the natural forest. In the natural forest 11 species of tree seedling were found, while in the plantation only five were found, and the seedling density was only one third of that in the natural forest. Across plots in both forests, understorey plant richness and diversity were negatively correlated with direct sunlight but not indirect sunlight, possibly because direct light plays a more important role in understorey plant growth. Conclusions: We report lower species and functional diversity and higher light availability in a natural hardwood forest than an adjacent 30‐yr C. japonica plantation, possibly due to the increased dominance of shade‐intolerant species associated with higher light availability. To maintain plant diversity, management efforts must be made to prevent localized losses of shade‐adapted understorey plants

attenuata

Antennaria neglecta Greenefield pussytoes;prairie pussytoesantennaire négligéeAntennaria neglectaJaffrey; Roadside rte. 137 at Dead Mars

asperifolia

Oryzopsis asperifolia Michauxrough-leaved mountain rice;white-grained mountain rice;rough mountain rice;rough-leaved ricegrass;winter grassoryzopsis à feuilles rudesasperifoliaSurry, No. end of Surry Mtn.Rich decid. Wood

occidentalis

Thuja occidentalis Linnaeuseastern white cedar;northern white cedar;northern white-cedar;eastern arborvitae;arborvitae;swamp cedarWhitefield; south of Burn's Pd.thuja swamptree 33 feet tal

uniflora

Monotropa uniflora LinnaeusIndian pipe;ghost pipe;one-flowered Indian pipe;convulsion root;ghostflowermonotrope uniflore;monotrope à une fleurMonotropa unifloraDublin, near Grimes Hill Rd.Wood

americana

Vallisneria americana MichauxAmerican eelgrass;wild celery;tapegrass;water celery;eelgrassvallisnérie d'Amérique;herbe à la barbotteamericanaHinsdale, Conn. R. No. of Vernon Dam2-3 ft of quiet wate

serriola

Lactuca serriola LinnaeusLactuca scariolaKeene, Royberry St. parking lotCracks in pavemen

macrophylla

Solidago macrophylla Banks ex Purshlarge-leaved goldenrodverge d'or à grandes feuilles;solidage à grande feuilleSolidago macrophyllaThompson & Meserve Purchase, Mt. JeffersonAlpine & subalpine openings of spruce-fir forest.4000 to 5300 feetSpruce, Fi

majus

Hypericum majus (A. Gray) Brittonlarge St. John's-wort;greater St. John's-wort;larger Canadian St. John's-wort;greater Canadian St. John's-wortmillepertuis majeurmajusWalpole, River Road So. at R.R. crossing

discolor

Salix discolor Muhlenbergpussy willow;lowland pussy willow;large pussy willow;American pussy willow;glaucous willowsaule discolore;chatons;saule p'tits-minousJaffrey, E. base of Gap Mtn.RoadsideShrub 2.7 m