Stand dynamics during a 12-year period in a second-growth stand in a cool temperature forest in northern Japan

In 1981 and 1993, trees over 2 m high were measured and mapped to clarify stand dynamics in two permanent plots of 0.1 ha in a secondary, cool temperate, mixed broadleaf/conifer forest after logging in the Tomakomai Experiment Forest, central Hokkaido, northern Japan. The species could be placed in two groups according to the change in basal area and density, and annual height growth:Quercus mongolica var.grosseserrata, Phellodendron amurense, Prunus sargentii andTilia japonica (Group I: GI) showed episodic regeneration and/or fast height growth;Acer mono, Acer palmatum var.matsumuae andSorbus alnifolia (Group II: GII) showed continuous regeneration and/or slow height growth. The age distribution of stems over 10 cm in d.b.h. suggests synchronous regeneration of GI and GII species. Vertical stratification was promoted during the 12-year period by the difference in annual height growth between the two species groups. Additional tree censuses in both remnant old-growth stands and second-growth stands after large scale blowdowns demonstrated thatQ. mongolica var.grosseserrata is most dominant in stands varying in the stages of development. Disturbance history and successional trends in dominant species implied that stand-devastating disturbances were responsible for the regeneration ofQ. mongolica var.grosseserrata in the study forest.     

Fine root mass in relation to soil N supply in a cool temperate forest

Soil inorganic nitrogen supply and fine root mass in the top layers of mineral soil (0–5 and 5–10cm) were investigated at upper and lower sites of a cool temperate forest where Fagus crenata and Quercus crispula dominate. At both sites, soil inorganic nitrogen supply was greatest in the 0–5cm layer. The predominant forms of soil inorganic nitrogen supply were NH₄⁺-N at the upper site and NO₃^–-N at the lower site. Fine roots were concentrated in the 0–5cm layer at the upper site, but not at the lower site. The form of supplied soil inorganic nitrogen supply can be important in determining the vertical distribution of fine roots.     

Three-dimensional dispersion of drosophilid flies in a cool temperate forest of northern Japan

Three-dimensional dispersion of drosophilid flies was studied within a secondary broad-leaved forest in relation to forest structure. The survey area included the forest margin and old canopy gaps and varied in the foliage height profile from place to place. Using multivariate analyses on the data of drosophilid dispersion, five microhabitats which were different from one another for drosophilids were recognized: (i) canopy layer; (ii) middle layer; (iii) floor layer of forest interior; (iv) upper layer of forest margin; and (v) herbaceous layer of forest margin and gap. The height of living space of canopy species was remarkably lowered at the forest margin. The forest edge was richer in both numbers of individuals and species than the forest interior from the overlap of the grassland and the forest canopy subcommunities and the addition of invaders from other habitats. However, no ‘edge’ species, which were mostly restricted to or spend most of their time in ecotones, were found. It is hypothesized that the above-ground forest structure consists fundamentally of three zones: (i) the canopy; (ii) the floor; and (iii) the edge. A significant positive correlation was found between the foliage height diversity and the degree of vertical habitat segregation among drosophilid species. The patchiness of vegetation structure influential to the three-dimensional dispersion in a forest drosophilid community was estimated to be on the scale of 110–450 m². This scale of subjective habitat patchiness or ‘ecological neighbourhood’ corresponds well with the most prevalent size of canopy gaps occurring in various forests.     

Effects of smoke, heat, darkness and cold stratification on seed germination of 40 species in a cool temperate zone in northern Japan

The effects of smoke, heat, darkness and cold stratification on seed germination were examined for 40 species with various life history attributes. These species establish in early successional stages on a volcano and are distributed in cool temperate zones of northern Japan. Smoke decreased seed germination in 11 species and increased it in one species, Leucothoe grayana . Germination of Polygonum longisetum was enhanced by a combination of smoke and cold, and that of Aralia elata by smoke and heat. Heat increased germination for three species and decreased it for one. Cold stratification broke dormancy in seeds of 11 species. Continuous darkness decreased germination of 22 species and did not increase germination for any species, showing that approximately half of the species require light for maximum germination. Although most species are sun plants that establish in early stages of succession and/or in disturbed areas, smoke and heat do not enhance germination of these species after disturbance, even when the disturbance is fire. Germination of slender and/or large seeds tends to be decreased more by smoke, probably because of their larger surface area. Light is more important than smoke and heat for detection of disturbance and for seed germination in this region. However, despite the low fire frequency in the region, germination of a few species was increased by fire-derived stimuli.     

Stand development and regeneration during a 33-year period in a seral Picea glehnii forest, northern Japan

Stand development and regeneration were studied during a 33-year period (1965-1998) in a 1-ha plot in a seral Picea glehnii forest in northern Japan. P. glehnii was mono-dominant in the upper canopy layer, but its understory trees were rarely found in 1965. Other species were scarcely observed in 1965. Many recruited saplings of Abies sachalinensis which had grown to > 5 cm diameter at breast height (DBH) by 1998 had become dominant in the understory layer. Mortality of P. glehnii canopy trees was low. Therefore, the stand basal area increased during the census period due to the growth of surviving canopy trees. Stand development brought about intense competition among trees by increasing local crowding for each tree, and promoted dominance of larger trees and suppression of smaller trees. Although growth rates of understory trees of the two conifers decreased with the increase in local crowding, the growth rate of A. sachalinensis was consistently higher than that of P. glehnii at all extents of local crowding. The recruitment rate (growing to 5 cm DBH) of the two conifers was less affected by local crowding. However, the number of recruits of P. glehnii was only about a quarter of that of A. sachalinensis during the census period because the regeneration of P. glehnii was largely restricted to fallen logs and within 1 m of the base of any live tree > 20 cm DBH. Therefore, our long-term study suggests that A. sachalinensis will dominate over P. glehnii in the seral forest because of higher recruitment and growth rates of the former than the latter in the understory.An erratum to this article can be found at     

Effects of rainfall events on soil CO2 flux in a cool temperate deciduous broad-leaved forest

The effects of rainfall events on soil CO₂ fluxes were examined in a cool temperate Quercus/Betula forest in Japan. The soil CO₂ fluxes were measured using an open-flow gas exchange system with an infrared gas analyzer in the snow-free season from August 1999 to November 2000. Soil CO₂ flux showed no significant diurnal trend on days without rain. In contrast, rainfall events caused a significant increase in soil CO₂ flux. To determine the effect of rainfall events and to evaluate more precisely the daily and annual soil carbon flux, we constructed a multiple polynomial regression model that included two variables, soil temperature and soil water content, using the soil CO₂ flux data recorded on sunny days. Daily soil carbon fluxes on sunny days calculated by the model were almost the same as those determined by the field measurements. On the contrary, the fluxes measured on rainy days were significantly higher than those calculated daily from the soil carbon fluxes by the model. Annual soil carbon fluxes in 1999 and 2000 were estimated using models that both do and do not take rainfall effects into consideration. The result indicates that post-rainfall increases in soil CO₂ flux represent approximately 16–21% of the annual soil carbon flux in this cool temperate deciduous forest.     

Gap formation, microsite variation and the conifer seedling occurrence in a subalpine old-growth forest, central Japan

To evaluate the effects of canopy gaps and forest floor microsites (soil, fallen logs, root-mounds, buttresses and stumps) on regeneration of subalpine forests, the gap regeneration and seedling occurrence of conifers (Abies mariesii, Abies veitchii, Picea jezoensis var. hondoensis and Tsuga diversifolia) were studied in two stands of a subalpine old-growth forest, central Japan. The percentage of gap area to total surveyed area was 11.2–11.3% in the stands. Gap regeneration was not common for P. jezoensis var. hondoensis and T. diversifolia. In contrast, gap regeneration by advanced regeneration was relatively common for Abies. Seedling occurrence of P. jezoensis var. hondoensis and T. diversifolia was restricted on elevated surfaces such as stumps and root-mounds, while Abies seedlings could occur on soil as well as on elevated surfaces. Rotten stumps were the most favorable microsites for conifer seedling occurrence, which covered small area in the forest floor. Although canopy gaps were not always favorable for seedling occurrence, all conifer seedlings were larger under canopy gaps than under closed canopy. Canopy gaps and forest floor microsites clearly affected seedling occurrence and growth of conifers. This suggests that regeneration of conifers is related to the difference of growth advantage under canopy gaps and favorable microsites for seedling occurrence.     

Differentiation and maintenance of topo-community patterns with reference to regeneration dynamics in mixed cool temperate forests in the Chichibu Mountains,central Japan

Topo-community structure and dynamics were studied in mixed cool temperate forests, using the regeneration dynamics, to clarify the maintenance mechanisms of community patterns along a microtopographic gradient. The 76 stands studied were classified into two groups (i.e. convex slope and concave slope stands). The soil surface was more eroded on the concave slope than on the convex slope, while water potential was not significantly different between topographies. On the convex slope, even-aged patches alternated between young phase patches dominated by shade intolerant species, such asAcer rufinerve andBetula grossa, and mature phase patches, withTsuga sieboldii andFagus crenata. A slower lateral growth rate ofTsuga canopy trees and the absence of suppressed saplings in the mature phase may prolong the gap phase, which provides a favorable situation to shade-intolerant species. On the concave slope, patch structure was less clear, and process of replacement of canopy species by previously suppressed individuals of the same species was seen in the mature phase, which was mainly composed ofF. crenata, Fagus japonica, Acer sieboldianum andStewartia pseudo-camellia. Gaps on the concave slope were formed frequently but were generally closed within 10 years by lateral growth of deciduous canopy trees and by upgrowth of suppressed trees, and thus some individuals underwent recurrent periods of suppression until they reached the canopy. We concluded that soil surface stability and gap encroachment pattern are critical to the maintenance of the community pattern along a microtopographic gradient.     

Gap-phase dynamics and coexistence of a long-lived pioneer and shade-tolerant tree species in the canopy of an old-growth coastal temperate rain forest of Chiloé Island, Chile

Aim A major question with regard to the ecology of temperate rain forests in south‐central Chile is how pioneer and shade‐tolerant tree species coexist in old‐growth forests. We explored the correspondence between tree regeneration dynamics and life‐history traits to explain the coexistence of these two functional types in stands apparently representing a non‐equilibrium mixture. Location This study was conducted in northern Chiloé Island, Chile (41.6° S, 73.9° W) in a temperate coastal rain forest with no evidence of stand disruption by human impact. Methods We assessed stand structure by sampling all stems within two 50 × 20 m and four 5 × 100 m plots. A 600‐m long transect, with 20 uniformly spaced sampling points, was used to quantify seedling and sapling densities, obtain increment cores, and randomly select 10 tree‐fall gaps. We used tree‐ring analysis to assess establishment periods and to relate the influences of disturbances to the regeneration dynamics of the main canopy species. Results Canopy emergent tree species were the long‐lived pioneer Eucryphia cordifolia and the shade‐tolerant Aextoxicon punctatum. Shade‐tolerant species such as Laureliopsis philippiana and several species of Myrtaceae occupied the main canopy. The stem diameter distribution for E. cordifolia was distinctly unimodal, while for A. punctatum it was multi‐modal, with all age classes represented. Myrtaceae accounted for most of the small trees. Most tree seedlings and saplings occurred beneath canopy gaps. Based on tree‐ring counts, the largest individuals of A. punctatum and E. cordifolia had minimum ages estimated to be > 350 years and > 286 years, respectively. Shade‐tolerant Myrtaceae species and L. philippiana had shorter life spans (< 200 years). Most growth releases, regardless of tree species, were moderate and have occurred continuously since 1750. Main conclusions We suggest that this coastal forest has remained largely free of stand‐disrupting disturbances for at least 450 years, without substantial changes in canopy composition. Release patterns are consistent with this hypothesis and suggest that the disturbance regime is dominated by individual tree‐fall gaps, with sporadic multiple tree falls. Long life spans, maximum height and differences in shade tolerance provide a basis for understanding the long‐term coexistence of pioneer and shade‐tolerant tree species in this coastal, old‐growth rain forest, despite the rarity of major disturbances.     

Determinants of the dramatic seasonal changes in the intake of energy and protein by Japanese monkeys in a cool temperate forest

Daily intake of gross energy (DGEI) and protein (DGPI) of Japanese monkeys in a cool temperature forest were investigated in different four seasons. As a result, dramatic seasonal differences in DGEI and DGPI were found: DGEI and DGPI in winter were significantly lower than those in spring and autumn, being only about 17–42% of those in the two seasons. DGEI and DGPI in summer were also lower than those in autumn and spring, being only about 29–52% of those in the two latter seasons. Seasonal comparisons of some variables on food qualities revealed that much lower values of DGEI and DGPI in winter and summer were influenced srongly not so much by the lower calorie and protein content of food as by the lower speed of dry weight intake. Multiple regression analyses for each food item revealed that the unit weight was a more important factor in determining the speed of dry weight intake than was the speed of unit intake. In addition, the speed of dry weight intake contributed much more to the speed of calorie and protein intake than did the content of calorie and protein. Multiple regression analyses, employing DGEI and DGPI (as dependent variables) and daily mean values of some variables related to food quality (as independent variables), revealed that the mean values of speed of calorie and protein intake on food items eaten in a day could explain 79.0% and 85.9% of the variance in DGEI and DGPI, respectively. In addition, the mean value of the speed of dry weight intake of food items eaten in a day can be used to explain 74.3% and 52.8% of the variance in DGEI and DGPI, respectively. These findings suggested that not only nutritional content of food but also the speed of dry weight intake strongly determined the nutritional condition of nonhuman primates. Am. J. Primatol. 41:267–288, 1997. © 1997 Wiley-Liss, Inc.     

Structure and regeneration of canopy species in an old-growth evergreen broad-leaved forest in Aya district,southwestern Japan

The population structure and regeneration of canopy species were studied in a 4 ha plot in an old-growth evergreen broad-leaved forest in the Aya district of southwestern Japan. The 200 m × 200 m plot contained 50 tree species, including 22 canopy species, 3,904 trees (dbh5 cm) and a total basal area of 48.3 m²/ha. Forty one gaps occurred within the plot, and both the average gap size (67.3 m²) and the total area of gap to plot area (6.9%) were small. Species found in the canopy in the plot were divided into three groups (A, B, C) based on size and spatial distribution patterns, and density in each tree size. Group A (typical species: Distylium racemosum, Persea japonica) showed a high density, nearly random distribution and an inverse J-shaped size distribution. Species in group B (Quercus salicina, Quercus acuta, Quercus gilva) were distributed contagiously with conspicuous concentration of small trees (<5 cm dbh) around gaps. However, the species in this group included few trees likely to reach the canopy in the near future. Group C included fast-growing pioneer and shade intolerant species (e.g. Cornus controversa, Carpinus tschonoskii, Fagara ailanthoides), which formed large clumps. Most gaps were not characterized by successful regeneration of group B and C but did appear to accelerate the growth of group A. Group B species appear to require long-lived or large gaps while group C species require large, catastrophic disturbances, such as landslides, for regeneration.     

Disentangling relationships between habitat conditions, disturbance history, plant diversity, and American black cherry (Prunus serotina Ehrh.) invasion in a European temperate forest

Whether non-native plant invasions are causes, consequences, or independent of the low species diversity in recipient ecosystems remains a debated question. We tried to test these three hypotheses in the special case of the American black cherry ( Prunus serotina Ehrh.), a gap-dependent tree species, which is invading European temperate forests. We compared plant communities, soil properties, and disturbance history between P. serotina -invaded and uninvaded paired-stands in a managed mixed forest. Relationships between invasion, disturbances, plant communities, and environmental conditions were investigated using redundancy analyses with variation partitioning. Several soil characteristics differed between paired stands, but were rather components of stand invasibility than invasion effects, except for topsoil available phosphorus. The disturbance history was similar among paired stands except for the amount of storm-induced tree falls, which correlated with the invader's density. Wild boar-disturbed soil areas were more important beneath P. serotina canopies, suggesting a positive feedback on its own establishment. Overall, species assemblages in invaded and uninvaded stands were similar; their ecological inconsistency suggested a management-sustained non-equilibrium. Habitat conditions and disturbances explained most of the variation in both plant diversity and P. serotina density, the last two factors exhibiting a weak direct association. We conclude that in managed forest ecosystems where plant communities are mainly driven by non-interactive factors and immigration processes, non-native plant species can naturalize without being directly influenced by measured features of the plant community in the receiving environment on the short term.     

秦岭落叶阔叶林25 ha森林动态监测样地物种组成与群落特征

秦岭落叶阔叶林是温带-亚热带过渡区保存较好的植被类型, 群落结构复杂。为了研究该过渡区植被的生物多样性维持机制, 按照CTFS (Center for tropical Forest Science)和中国森林生物多样性监测网络(CForBio)的建设标准, 于2015年在陕西省佛坪国家级自然保护区的落叶阔叶林建立了一块面积25 ha的动态监测样地。本文对样地内胸径(DBH) ≥ 1 cm的所有木本植物进行了调查和统计, 分析了其物种组成、区系特征、径级结构和空间分布格局。结果表明: 样地内DBH ≥ 1 cm的木本植物独立个体有47,739株, 隶属于36科66属119种。温带区系成分的科和属分别占总科数和总属数的41.18%和60.00%, 温带区系特征明显。稀有种有51种, 占总树种的42.86%。落叶树种有106种, 占总树种的89.07%, 在样地内占绝对优势。重要值≥ 1的物种共有20个, 分别占样地总个体数和总胸高断面积的70.35%和57.41%, 重要值最大的物种分别是乔木层的锐齿栎(Quercus aliena var. acutesrrata)、亚乔木层的水榆花楸(Sorbus alnifolia)和灌木层的刺叶栎(Q. spinosa)。样地内所有个体的平均胸径为8.61 cm, 整体径级分布呈倒”J”型, 小径级个体较多, 群落更新良好。除了太白杨(Populus purdomii), 样地内优势种表现出大尺度的聚集分布, 且它们的分布与生境紧密相关, 不同物种表现出不同的生境偏好。     

暖温带-北亚热带过渡区落叶阔叶林群落特征

白云山落叶阔叶林是暖温带-北亚热带生态过渡区保存较完好的植被,具有北亚热带向暖温带的过度性质,群落结构相对复杂,物种种类相对丰富。参照巴拿马巴洛科罗拉多岛(Barro Colorado Island,BCI)样地的技术规范,于2015年在白云山国家森林公园建立了一个5 hm~2固定监测样地,调查并鉴定了样地内胸径≥1 cm的木本植物。基于首次调查数据从物种组成、径级结构、重要值、群落分类和分布格局等方面进行了分析,结果表明:(1)样地共有17963株个体,隶属于34科55属93种;(2)该群落以锐齿槲栎(Quercus aliena var.acuteserrata)、华山松(Pinus armandii)、三桠乌药(Lindera obtusiloba)、漆树(Toxicodendron vernicifluum)占优势,稀有种占总种数的36.56%,偶见种占总种数的30.11%;(3)所有物种的径级结构分布呈倒"J"型,表明群落内有充足的幼苗,群落更新状况良好;(4)多元回归树经过交叉验证,以凹凸度和平均海拔将样地植被划分为3类,Ⅰ:锐齿槲栎-华山松-三桠乌药-秦岭木姜子-河南海棠群落;Ⅱ:锐齿槲栎-华山松-漆树-连翘群落;Ⅲ:锐齿槲栎-白桦-白檀-照山白群落;(5)点格局分析表明样地内优势种主要表现为聚集分布格局。研究结果有助于增加人们对暖温带-北亚热带生态过度区内森林群落的认识,为此区域内植物群落的管理和保护积累基础资料。