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Regeneration niches for tree seedlings are defined as possessing the biotic and abiotic requirements to successfully replace adults. However, two critical discrepancies obscure our understanding of the role of regeneration niches in forest community assembly: a weak association between seedling assemblages and environmental factors, and an uncoupling between seedling and adult-tree assemblages. However, understory plants, which may interact with microenvironments and seedlings, may be a better spatial descriptor of regeneration habitats. To test this, the spatial variations of seedling assemblages in a montane cloud forest of Taiwan were analyzed in terms of their association with neighborhood assemblages of understory plants, the shrub layer, and overstory trees, as well as environmental variables. We found that the understory plant spatial structure contributed most in explaining spatial variations of the seedling assemblages (especially for widespread Lauraceae and patchy Fagaceae) and facilitated the identification of patches of different regeneration habitats for specific seedling assemblages. Moreover, among these regeneration patches, tall herbs affected seedling density and diversity differently. We found segregation between tall herbs and Lauraceae seedlings, indicating that tall herbs shape seedling assemblages and uncouple the association between seedling and adult stages. However, positive covariations between seedlings/tall herbs and between seedlings/adults were found for Fagaceae and Pentaphylacaceae in different regeneration patches, suggesting that positive, neighboring effects and dispersal limitation may cause the patchy distribution of seedling assemblages and affect their coupling with adults. Thus, the understory plant spatial structure shapes seedling assemblages and provides a better link to spatial associations with regeneration habitats.

How micro-topography affecting plant communities classification and species composition at one stand-level was investigated through the plant communities and species composition varied across fine-scale environmental heterogeneity at the 25-ha Lienhuachih broad-leaved forest dynamics plot (FDP). All free-standing woody plants with diameter at breast height ≧1 cm were identified, measured, tagged and mapped. Four plant communities were identified and represented with dominant and indicating species based on two-way indicator species analysis (TWINSPAN). Type I, Pasania nantoensis - Randia cochinchinensis, locating on the ridge and the highest elevation was with the highest stem density; Type II, Mallotus paniculatus - Engelhardtia roxburghiana, locating on the upper slope was an ecotone between type I and type III, with the middle stem density and basal area among four plant community types; Type III, Diospyros morrisiana - Cryptocarya chinensis, locating on the lower slope and stream side was with lower stem density but the highest species heterogeneity; and Type IV, Machilus japonica var. kusanoi - Helicia formosana locating on west stream side was with the lowest stem density and basal area. Detrended Correspondence Analysis (DCA) results showed nearly 27.11% of the plant species composition was attributable to micro-topographic variables. Ridge distance, stream distance and convexity were the most important factors effected the changes of plant community and species composition. Classification and regression tree (CART) method was also used to examine the relationship between each single specie and micro-topographic variables. Over 70% species had more than 27.11 % variations which explained by DCA results. To conclude, our results support the existence of habitat association and niche divergence related to micro-topography in a subtropical evergreen broad-leaved forest.

There is a growing need to understand, and ultimately manage, carbon storage by forest ecosystems. Broad-leaved evergreen forests of Taiwan provide an outstanding opportunity to examine factors that regulate ecosystem carbon storage. We utilized data from three Taiwan Forest Dynamics Plots (FS, LHC, and PTY) in which every tree is identified, measured, tagged and mapped, to examine factors regulating carbon storage as estimated from aboveground biomass. Allometric equations were used to estimate the aboveground biomass of each tree, and a model building procedure was used to examine relationships between plot-level aboveground biomass (AGB; Mg/ha) and a suite of topographic and biotic factors. We found that our study sites have AGB values comparable to some of the most carbon dense forests in the world. Across all three sites, maximum biomass was contained in the taxonomic families Fagaceae, Lauraceae and Theaceae. In the FS site, we identified slope convexity (P = 0.03) and elevation (P < 0.001) as topographic predictors of AGB and found that maximum AGB was found in topographically flat areas. In FS, stem density (P < 0.001) was a significant biotic predictor of AGB and the maxima occurred at intermediate densities. In LHC, we found that convexity (P < 0.001) and slope (P < 0.001) were significantly related to AGB which was maximized along a topographic ridge in the plot. Species richness (P < 0.001) was a significant biotic predictor of AGB in LHC, and the relationship indicated slightly higher AGB at higher levels of species richness. The only significant factor related to AGB in PTY was species richness (P = 0.02). Further work is needed to seek a mechanistic understanding of topographic factors and species richness as drivers of carbon storage in forests.

Understanding processes underlying spatial distribution of tree species is fundamental to studying species coexistence and diversity. This study modeled point patterns of tree distribution, expressed by Cartesian coordinates of individual trees within a mapped forest stand, for the purpose of identifying processes that may generate spatial patterns of tree communities. We used four primary point pattern processes (homogeneous Poisson process, inhomogeneous Poisson process, homogeneous Thomas process, and inhomogeneous Thomas process) to model tree distribution in two stem-mapped forests in Taiwan, Republic of China. These four models simulate spatial processes of habitat association and seed dispersal, allowing us to evaluate the potential contribution of habitat heterogeneity and dispersal limitation to the formation of spatial patterns of tree species. The results showed that the inhomogeneous Thomas process was the best fit model and described most of the species studied, suggesting that spatial patterns of tree species might be formed by the joint effects of habitat associations and dispersal limitation. The homogeneous Thomas process that models the effect of dispersal limitation was the second best model. We also found that the best fit models could be predicted by species attributes, including species abundance and dispersal mode. The significant traits, however, differed between the two study plots and demonstrated site-specific patterns. This study indicated that the interactive operation of niche-based (habitat heterogeneity) and neutral-based (dispersal limitation) may be important in generating spatial patterns of tree species in forest communities.

Naturalized flora of Taiwan has been increasing in the past six after the first catalogue was compiled in 2002. In order to probe into the increasing pattern behind this dramatic growth of potential invaders, we compiled and evaluated newly added naturalized species in a quest for better understanding. Furthermore, naturalized species shared with neighboring regions, such as Mainland China and Japan, were estimated as well. The results revealed that two-thirds of these newly recruited species naturalized before 2002, and only 77 actually naturalized after 2002. The proportion of naturalized flora in the native species pool increased from 8% to 12%. The compositions, origins, and life forms of these potential invaders before and after 2002 were similar with slight fluctuations presented in the ranks of the dominant families. Number of species shared with neighboring regions multiplied due to the fast growth of the naturalized flora in Taiwan; nevertheless, the number might be understated due to the inaccessibility of the latest naturalized floras from neighboring regions. The doubled flora of naturalized species in the past six years implies insufficient attention to plant invasions and lag phases of invasion. The expansion of naturalized flora in Taiwan also increased the pools of naturalized species shared with neighboring areas, including Mainland China and Japan.

A 8.37-ha plot of the broad-leaved forest at an elevation of about 2000 m in the upstream basin of the Nantzuhsienhsi River in mid-southern Taiwan was set up for long-term monitoring of forest dynamics. All stems with diameter at breast height (d.b.h.) ≧ 1 cm were identified, measured, tagged, and mapped to analyze the forest composition, structure and species diversity of the plot. A total of 18,790 woody plant individuals, belonging to 64 species in 27 families, were recorded. The dominant families were Lauraceae, Fagaceae, and Theaceae, accounting for 78.8% of total individuals. The dominant species were Castanopsis carlesii, Machilus japonica, Listea acuminate, and Cyclobalanopsis stenophylloides. The most abundant species in the canopy layer was Castanopsis carlesii, in the subcanopy layer was Listea acuminate, and in the shrub layer were Machilus japonica and Listea acuminata. Four plant communities were identified based on Two-way Indicator Species Analysis (TWINSPAN) classification, including three evergreen forest types and one deciduous forest type. The three evergreen types are Machilus japonica type, locating on the east and west valleys and partial lower slopes, Machilus japonica-Castanopsis carlesii type, locating on middle to lower slopes and the central dry valley, and Schima superba-Castanopsis carlesii type, locating on eastern ridge and upper slopes. The deciduous type is Alnus formosana forest which is distributed on mid-west and southwestern ridges. The means of species number, density and basal area for different forest types declined gradually from ridge to valley habitats. These results reveal that topography is an important factor which is closely related to the distribution of evergreen broad-leaved forest types in the plot.

The forest structure and woody species composition were investigated in a montane rainforest of Mt. Lopei in northern Taiwan. All stems ≥ 1 cm dbh were measured and identified for a permanent plot of 1-ha (1,136 to 1,164 m asl.). Approximately 12,934 stems of 70 taxa in 31 families were found. The most abundant families were Fagaceae, Illiciaceae, and Theaceae, representing 51.5% of the individuals. The dominant species, based on basal areas were Cyclobalanopsis longinux, Machilus thunbergii, Cyclobalanopsis sessilifolia, Illicium arborescens, Diospyros morrisiana, and Meliosma seqimulata. Comparison of TWINSPAN groupings with the DCA ordination showed a definitive separation of forest types along a topographic gradient. The categorized forest types were the Cyclobalanopsis longinux-Myrsine seguinii type on the ridgetop and northeastern slope facing strong northeastern monsoon, and the Illicium arborescens-Itea parviflora type on the relatively protected southwestern slope. Evident differences of the composition and structure were observed between these two forest types. Size-class structures of most species showed an inverse J-shaped or an inverse L-shaped distribution, both indicators of a continuous recruitment in this permanent plot.

The genus Sciaphila (Triuridaceae) is revised based on comparative morphological and palynological studies in Taiwan. Four species are recognized, i. E. Sciaphila arfakiana Becc., S. Maculata Miers, S. ramosa Fukuy. & T. Suzuki, and S. secundiflora Thwaites ex Benth. Sciaphila arfakiana and S. maculata are new record to Flora of Taiwan and S. secundiflora distributed in Kueishan Island is a new distribution. SEM micrographs of pollen grains, a key to species, species descriptions, and taxonomic notes are provided.

The first collection of Quercus aliena Blume var. acutiserrata Maxim. Ex Wenz. In Taiwan was made by Y. Shimada in 1924 from Hongmao. Since then, no other specimen had ever been collected. Recently, this species was rediscovered from Fengshan (3 km south of Hongmao) in Hsinchu County. On closer studies it was found to be the typical variety of Q. aliena Blume rather than the name recognized by Shimada. The population of Q. aliena is quite small at that limited location, and is vulnerable to human impacts. Therefore, it is necessary to take steps to conserve the habitat as soon as possible. The taxonomic treatment, morphological descriptions, photographs and notes of the species are given here. A key to distinguish it from the other three closely related Taiwanese species is also provided.

台湾における高い人口密度と急速な経済発展にもかかわらず，常緑広葉樹林は引き続き台湾島の面積の32% を占めている。この森林は海岸域から海抜2500 m に分布し，多様な植物相と4 つの主要森林型を支えている。779 の調査区での森林の植物相は木本植物570 種を含み， 234 属， 82 科に及んでいる。最も種の数が多い科はクスノキ科，ブナ科，ツバキ科，アカネ科， トウダイグサ科であった。本研究の第１の目的は，台湾における常緑広葉樹林の4 主要型について比較解釈をすることである。第2 の目的は過去3 世紀に亘るこれらの森林の管理と保護の状況を概括することである。