Annual periodicity of fruiting in temperate forests in Yakushima,Japan

Fruiting phenology, assessed by seed fall, in five warm-and cool-temperate forests on Yakushima Island, southern Japan, was studied for two years in one 50 m × 50 m plot and for four years in four 100 m × 50 m plots. The elevation of the plots ranged between 170 and 1200 m a.s.l. Seed fall phenology showed annual periodicity in all five plots. This was clear when assessed by the number of species but became less clear when assessed by the biomass of seed litter. Community-level annual periodicity was based on the prevalence of population-level annual periodicity and interspecific synchronization of the fruiting peak from autumn to winter. Fleshy fruits had peaks of seed fall in a wider range of months than non-fleshy fruits, since it is sometimes beneficial to bear fruit outside the community-level fruiting peaks in order to avoid interspecific competition for animal seed dispersers. No consistent effect of climatic factors on seed fall phenology was detected.     

Diversity, distribution and resource values of woody climbers in tropical forests of southern Eastern Ghats, India

We investigated the distribution and resource values of liana species assessed in six hill complexes of southern Eastern Ghats, India. 143 liana species (DBH (diameter at breast height) ≥1.5 cm) and 32,033 liana individuals were recorded from 110 transects (0.5 ha each covering 55 ha area) in the study sites. The resource values of lianas were broadly categorized into ecological and economic importance. About 90% (129) of liana species and 96% (30,564) of liana individuals were established ecological/economic values. Fruit rewards provided by 76 species and 20,325 individuals constituted the major resource of ecological importance. 82 species and 21,457 liana individuals are of economic importance as medicine, edible fruits, edible and medicinal values, and yet others are used for different domestic purposes including furniture, fuel wood, rope making etc.. Ecologically, the prevalence of succulent diaspores in lianas of Indian Eastern Ghats indicates the animal dependence of many liana species for dispersal and underlines the need for a holistic and whole-forest conservation approach in maintaining forest biodiversity.     

Compression and overlap of unique vegetation system of subtropical mountain resembling tropical and temperate forests along elevation

The purpose of this study was to investigate how forests on subtropical mountains, which resembled tropical and temperate forests, were assembled, and to examine the compression and overlap of vegetations. We established 344 sample plots (400 m²) located at different altitudinal gradients ranging from 16 to 3,500 m above sea level (ASL) in Hsueshan Range northern Taiwan. Vegetation types were classified by TWINSPAN and the results of DCA were used to analyze the changes in vegetation types along elevation. Vegetation I was composed of the species of Euphorbiaceae, Moraceae, and Rubiaceae, which were taxa of tropical floristic elements, and the extent of this vegetation was limited below 1,500 m ASL. Vegetation II was defined into two subtypes, which were distributed from 1,000 to 2,500 m ASL, and were composed predominantly of Chamaecyparis and Tsuga, respectively. Our data also revealed that vegetation II contained co-dominants of species from families Lauraceae and Fagaceae. Moreover, evergreen broadleaved trees similar to tropical mountain forests were found to have narrower altitudinal ranges on subtropical mountains, whereas coniferous forests resembled temperate areas and were characterized by endemic conifer species. Vegetation III, from 2,500 to 3,500 m ASL, was characterized by endemic conifer species, Abies and Tsuga. Interestingly, deciduous forest was almost absent in this area and Fagus was the only tree type on a small mountain ridge. Data obtained from this study will help in raising conservation awareness for subtropical mountains since unique patterns of compression and overlap characteristics of tropical and temperate resembling forests were evident.     

Stand structure,phenology and litterfall dynamics of a subtropical mangrove Bruguiera gymnorrhiza

We evaluated the phenology and litterfall dynamics of the mangrove Bruguiera gymnorrhiza(L.)Lamk along the Okukubi River, Okinawa Island, Japan.Over 3 years, this species showed the highest litterfall of leaves and stipules in summer and the lowest litterfall in winter. From Kendall's coefficient of concordance, the monthly changes in leaf, stipule, and branch were strongly and significantly concordant among years. Leaf and stipule litterfall could be governed by monthly maximum wind speed, monthly day length, and monthly mean air temperature. Branch litterfall depended on monthly maximum wind speed and monthly rainfall, and increased exponentially with increasing monthly maximum wind speed. Mean total litterfall was 11.8 Mg ha~(-1)yr~(-1), with the largest component being leaf litterfall(65.8 %). Annual leaf litterfall per plot was almost constant regardless of the tree density of the plot. Mean leaf longevity was 18 months.Flower and mature propagule litterfall might be influenced by monthly mean air temperature, monthly day length and monthly mean air temperature. The average development periods from flower buds to flowers and flower buds to mature propagules were 1 and 8 months, respectively.Except for leaf and branch, all vegetative and reproductive organ litterfall had clear annual cycles. B. gymnorrhiza showed a positive correlation between leaf production and reproductive organ production.     

Nitrification and denitrification in subalpine coniferous forests of different restoration stages in western Sichuan, China

Nitrification is the biological conversion of organic or inorganic nitrogen compounds from a reduced to a more oxidized state. Denitrification is generally referred to as the microbial reduction of nitrate to nitrite and further gaseous forms of nitric oxide, nitrous oxide and molecular nitrogen. They are functionally interconnected processes in the soil nitrogen cycle that are involved in the control of long-term nitrogen losses in ecosystems through nitrate leaching and gaseous N losses. In order to better understand how nitrification and denitrification change during the process of ecosystem restoration and how they are affected by various controlling factors, gross nitrification rates and denitrification rates were determined using the barometric process separation (BaPS) technique in subalpine coniferous forests of different restoration stages. The results showed that forest restoration stage had no significant effects on gross nitrification rates or denitrification rates (One-way ANOVA (analysis of variance), p < 0.05). There was no significant difference in the temperature coefficient (Q ₁₀) for gross nitrification rate among all the forest sites (One-way ANOVA, p < 0.05). Gross nitrification rates were positively correlated with water content (p < 0.05), but not with soil pH, organic matter, total nitrogen, or C/N ratios. Denitrification rates in all the forest soils were low and not closely correlated with water content, soil pH, organic matter, or total nitrogen. Nevertheless, we found that C/N ratios obviously affected denitrification rates (p < 0.05). Results from this research suggest that gross nitrification is more responsible for the nitrogen loss from soils compared with denitrification. Translated from Journal of Plant Ecology, 2006, 30(1): 90–96 [译自: 植物生态学报]     

Liana habitat and host preferences in northern temperate forests

Lianas and other climbers are important ecological and structural components of forest communities. Like other plants, their abundance in a given habitat depends on a variety of factors, such as light, soil moisture and nutrients. However, since lianas require external support, host tree characteristics also influence their distribution. Lianas are conspicuous life forms in tropical regions, but in temperate areas, where they are less prominent, little is known about factors that control their distributions in these forests. We surveyed the climbing plant species in 20 mature (100 years and greater) forested habitats in the Midwest USA at a variety of levels from simple presence/absence, to ground layer abundances, to those species that had ascended trees. We also examined attributes of the tree species with climbers attached to them. Using cluster analysis, we distinguished five different tree communities in our survey locations. We determined that 25% of the trees we surveyed had one or more lianas attached to it, with Parthenocissus quinquefolia (Virginia creeper) the most common climbing species encountered. Canopy cover and soil attributes both influenced climber species presence/absence and ground layer climber abundance. The proportion of liana species of a given climbing type (roots, stem twiner, tendril climber) was significantly related to the DBH of the host tree, with more root climbers and fewer stem and tendril climbers on large trees. In general, the DBH of climbing lianas had a significant positive relationship to the DBH of the host tree; however this varied by the identity of the liana and the tree species. The greater the DBH of the host tree, the higher the probability that it was colonized by one or more lianas, with tree species such as Pinus banksiana (jack pine) and Quercus alba (white oak) being more susceptible to liana colonization than others. Finally, some liana species such as Celastrus scandens (American bittersweet) showed a preference for certain tree species (i.e., P. banksiana) as hosts. The information obtained about the relationship between the tree and climber community in this study provides insight into some of the factors that influence liana distributions in understudied temperate forest habitats and how lianas contribute to the structure of these mature forests. In addition, these data can provide a point of comparison to other liana communities in both temperate and tropical regions.     

Seed dispersal phenology and dispersal syndromes in a subtropical broad-leaved forest of China

This study describes the dispersal phenology and syndromes in Gutianshan 24 ha plot in a subtropical broad-leaved forest of China. The 130 0.5 m² seed traps collected 69,115 mature seeds, representing 27 species (belonging to 24 genera, and 15 families) in 12 months. One marked peak in the number of seeds and species during the year was found in dry season (November). Zoochory was the most common dispersal syndrome (70.4%), followed by anemochory (18.5%), ballistic dispersal (11.1%). Among fruit types, berry (33%), capsule (22%), nut (18%), and drupe (11%) were common in the subtropical evergreen forest. In fruit color, brown was the commonest (40%), followed by dark brown (30%), black (15%), red (11%), and yellow (4%). Overall, the community level seed rain study revealed that one marked peak in seed number occurred in the middle of dry season; zoochory was the principal dispersal mode of woody plants in subtropical forest, and dry seasons favor seed dispersal by animal and wind.     

Roads, fire and aggressive competitors: Determinants of bird distribution in subtropical production forests

Forestry practices such as fuel-reduction burning and maintenance of road networks can negatively impact avian assemblages, both directly by changing habitat structure and indirectly by creating conditions favorable for predators or competitors. The Brigalow Belt forests include some of the largest contiguous areas of native forest in the temperate and sub-humid zones of eastern Australia. Over 1 million ha of these forests are proposed to be converted from forestry to conservation tenure, yet the impacts on the avifauna of current and potential future forest management practices are not known. We investigated the influence of road edges and habitat type and structure on the avifauna of a 356 000 ha forest. Survey sites were either <50 m or >300 m from a road, and in either cypress pine Callitris glaucophylla forest, spotted gum Corymbia citriodora forest with a regenerating cypress pine/buloke Allocasuarina luehmannii understorey or spotted gum forest with an open understorey due to fuel-reduction burning. The avifauna differed significantly among vegetation types but not with proximity to a road, with the greatest differences between cypress pine and both types of spotted gum forest. The noisy miner Manorina melanocephala, an aggressive avian competitor, appears to be the factor mediating these assemblage-level differences. Noisy miners were rare in cypress pine forest but were three times more numerous than any other species in spotted gum forest. Spotted gum forest with a regenerating understorey had fewer noisy miners. Although total bird abundance was highest in open spotted gum forest, the species richness and abundance of passerines smaller than noisy miners was significantly lower in this forest type. Abundance of small passerines was eight times higher in sites where <3 noisy miners were recorded. Only one species, the eastern yellow robin, was influenced by proximity to a road edge. Cypress pine forest is potentially an important refuge for smaller birds. The results suggest that burning regimes that reduce regeneration of the cypress pine and buloke subcanopy in spotted gum forest potentially are exacerbating the problem of noisy miner domination of the avifauna.     

Natural conifer regeneration patterns in temperate forests across the Inland Northwest,USA

Key message

Natural regeneration patterns of conifer species were studied. Seedling regeneration follows patterns responding to stand structure and site condition factors along shade and drought tolerance gradients. Our findings can assist in adaptive forest management for maintaining sustainable regeneration and plant biodiversity.

Context

Seedling regeneration can vary with stand factors of overstory trees and understory non-tree vegetation and site conditions.

Aims

Natural seedling regeneration patterns of coniferous species were investigated using Forest Inventory and Analysis (FIA) data of 10 common species across the Inland Northwest, USA.

Methods

Zero-inflated negative binomial models were developed to understand the responses of natural regeneration to stand factors and site conditions.

Results

Seedling occurrence varies along shade and drought tolerance gradients responding to stand structure and site conditions. Two moderate shade-tolerant species of different drought tolerance contributed as a transition. Strong response patterns were revealed for seedling density, in which seedling density was improved with the presence of conspecific trees while limited by competition, especially from the understory vegetation layer.

Conclusion

Overstory structure and understory vegetation could improve or hinder natural regeneration of coniferous tree species given different shade tolerance and site conditions. Our findings can be effectively implemented in adaptive forest management for maintaining sustainable regeneration of specific conifers in broad temperate mixed forests.

     

Effects of stand density on ecosystem properties of subalpine forests in the southern Rocky Mountains, USA

? Mixed coniferous, subalpine forest communities in the Rocky Mountains are historically dense and have experienced infrequent, high-severity fire. However, many of these high-elevation stands are thinned for a number of perceived benefits.

? We explored the effects of forest stand density on ecosystem properties in subalpine forests in Colorado, USA, 17–18 y after forests were managed for timber.

? Forest structure significantly altered the composition and chemical signature of plant communities. Previously managed stands contained lower density of overstory trees and higher ground cover compared to paired reference stands. Foliar phenolic concentration of several species was negatively related to basal area of overstory trees. Furthermore, reductions in stand density increased total foliar phenolic:nitrogen ratios in some species, suggesting that gap formation may drive long-term changes in litter quality. Despite significant changes in forest structure, reductions in stand density did not leave a strong legacy in surface soil properties, likely due to the integrity of soil organic matter reserves.

? Changes in forest structure associated with past management has left a long-term impact on plant communities but has only subtly altered soil nutrient cycling, possibly due to trade offs between litter decomposability and microclimate associated with reductions in canopy cover.

     

Differences in leaf phenology between juvenile and adult trees in a temperate deciduous forest

In a deciduous forest, differences in leaf phenology between juvenile and adult trees could result in juvenile trees avoiding canopy shade for part of the growing season. By expanding leaves earlier or initiating senescence later than canopy trees, juvenile trees would have some period in high light and therefore greater potential carbon gain. We observed leaf phenology of 376 individuals of 13 canopy tree species weekly over 3 years in a deciduous forest in east central Illinois, USA. Our objectives were: (1) to quantify for each species the extent of differences in leaf phenology between juvenile and conspecific adult trees; and (2) to determine the extent of phenological differences between juvenile Aesculus glabra Willd. and Acer saccharum Marsh. trees in understory and gap microhabitats. All species displayed phenological differences between life stages. For 10 species, bud break was significantly earlier, by an average of 8 days, for subcanopy individuals than for canopy individuals. In 11 species, completion of leaf expansion was earlier, by an average of 6 days, for subcanopy individuals than for canopy individuals. In contrast, there were no significant differences between life stages for start of senescence in 10 species and completion of leaf drop in nine species. For eight species, leaf longevity was significantly greater for subcanopy individuals than for canopy individuals by an average of 7 days (range = 4-10 days). Leaf phenology of subcanopy individuals of both Aesculus glabra and Acer saccharum responded to gap conditions. Leaf longevity was 11 days less in the understory than in gaps for Aesculus glabra, but 14 days more in the understory than in gaps for Acer saccharum. Therefore, leaf phenology differed broadly both between life stages and within the juvenile life stage in this community. A vertical gradient in temperature sums is the proposed mechanism explaining the patterns. Temperature sums accumulated more rapidly in the sheltered understory than in an open elevated area, similar to the canopy. Early leaf expansion by juvenile trees may result in a period of disproportionately higher carbon gain, similar to gains made during summer months from use of sun flecks.     

Seasonal variations in photosynthesis of Picea morrisonicola growing in the subalpine region of subtropical Taiwan

From January 1999 to May 2001, we investigated seasonal variations in the photosynthetic capacity of Taiwan spruce (Picea morrisonicola Hay.) growing in the subalpine region of subtropical Taiwan (23 degrees 29' N, 120 degrees 53' E, 2600 m a.s.l.). Photosynthetic capacity (near light-saturated net photosynthetic rate, Pnsat, chlorophyll fluorescence (Fv/Fm) and soluble protein concentration of needles all increased from mid or late spring to early winter. Even when minimum air temperature of the measuring day dropped to near 0 degrees C, Pnsat remained at about 20% of the highest value observed in winter. There was a curvilinear relationship between Fv/Fm and the minimum or mean air temperature of the measuring day. The increase in Fv/Fm with temperature was slowed when the daily mean air temperature was above 7 degrees C, or the minimum air temperature was above 3 degrees C; however, when air temperatures dropped below these values, Fv/Fm varied sharply. Seasonal variations in Pnsat paralleled those in Fv/Fm and needle soluble protein concentration. In early or mid spring when air temperature and Fv/Fm increased, Pnsat and soluble protein concentration remained low. Multiple regression analysis showed that seasonal variations in Pnsat were affected by Fv/Fm, air temperature and needle soluble protein concentration, and the multiple regression equation could be used to estimate Pnsat in different seasons. We conclude that the decrease in photosynthetic capacity of Taiwan spruce in winter and its subsequent recovery in spring were mainly caused by photoinhibition and its reversal, and changes in needle soluble protein concentration. Another possible explanation for the delayed recovery of photosynthetic capacity in spring may be associated with the slow increase in needle soluble protein concentration.     

Nutrient dynamics of foliar litter in reciprocal decomposition in tropical and subtropical forests

In order to explore the release of nutrients and the effects of global warming on the decomposition rate of forest litter, an experiment is designed to reciprocally decompose forest foliar litter in two sites across climatic zones: Mt. Jianfengling in Hainan Province in the tropics and Mt. Dinghushan in Guangdong Province in the subtropics. The two sites have similar altitudes, soil types, annual mean rainfall and seasonality of dry and wet. The main difference between these two sites is the annual mean temperature with the difference of 3.7°C. Foliar litters of 10 native dominant tree species have been collected respectively from the two sites and divided into single-species litter and mixed litter. They are decomposed reciprocally in the two sites. The results indicate that litter decomposes in the tropical site 1.36–3.06 times more rapidly than in the subtropical site. Apparent Q ₁₀, calculated on the basis of the temperature difference between the two sites, ranges from 3.7 to 7.5. The return amount of N, P and C will increase by 32.42, 1.033 and 741.1 kg/hm², respectively in Mt. Dinghushan in the first year’s litter decomposition under the prevailing temperature condition. Only in Mt. Dinghushan is the correlation between decomposition rate constant and initial litter quality high and significant in the ratio of lignin to N, lignin, the ratio of lignin to P, HLQ and C. This is not the case at Mt. Jianfengling. __________ Translated from Journal of Beijing Forestry University, 2005, 27(1): 24–32 [译自: 北京林业大学学报, 2005, 27(1): 24–32]     

永顺落叶木莲开花与结实物候学研究

首次报道永顺落叶木莲开花与结实物候学特征。其花期在3月中旬至5月上旬,果期在4月中旬至10月上旬。其间有3次花周期和3次果实发育期,每次花周期和果实发育期天数不同。低海拔比高海拔开花早,落花期亦早,开花周期较短;低海拔较高海拔的果发育期长,种子散落期晚,果实最佳采集期在9月20日至9月30日。     

西藏红豆杉资源的保护和利用

通过对西藏喜马拉雅红豆杉（Ｔａｘｕｓ ｗａｌｌｉｃｈｉａｎａ）和云南红豆杉（ｔａｘｕｓ．ｙｕｎｎａｎｅｎｓｉｓ）资源的调查，分析讨论了西藏红豆杉资源分布的现状及特点，提出了保护和利用红豆杉资源的途径。     

Diversity loss of lichen pine forests in Poland

In Central Europe, deciduous forests are the dominant community type and lichen pine forests are restricted to certain areas with extremely nutrient-poor and xeric soil types. In recent decades, a retreat of vegetation of oligotrophic habitats has been observed in Central Europe. In this study, we assessed changes of lichen pine forests in Poland: within the main area of the range in Central Europe. We used two sets of data collected at a local and regional (nation-wide) scale. On the basis of data from semi-permanent plots, we examined changes in the structure and species composition of lichen pine forests over 33 years at the local scale (between 1975 and 2008). To compare trends at the regional scale, we used data collected in the Polish Vegetation Database (PVD). For identification of lichen pine forests we determined a group of co-occurring Cladonia species. We analyzed differences in species richness and vegetation structure at the regional scale in tree time periods (1) between 1951 and 1969, (2) 1970 and 1989, and (3) 1990 and 2011. We found that changes in lichen pine forests are primarily quantitative at both scales. Our results indicate that the abundance of Cladonia species is limited by strong competitors, i.e., vascular plants and bryophytes, which may be explained by eutrophication and climate warming. Only pine forests with a minor abundance of lichens have chances to persist in the vegetation of Central Europe, while the most valuable communities with high abundance of indicators will disappear. Though an assessment of the total decrease in the area of lichen pine forests is not possible with the available regional data, local observations indicate a large decline in the area of lichen pine forests in Central Europe. Their conservation seems to be a serious challenge, because it is difficult to provide optimal conditions for all indicators.     

Diversity and dominant species of arthropods in different forests of Aershan, Inner Mongolia

Taking different forests in Aershan of Inner Mongolia as sample plots,diversity and dominant species of arthropods were studied.The results show that two classes,17 orders,68 families,130 species and 3742 individuals were identified and 92.31% of total species appeared in natural forests,and 75.38% of total species appeared in plantations.The orders of Lepidoptera,Coleop-tera,Diptera and Hymenoptera covered most of the collected arthropods.In different forest types,diversity indices is natural mixed forests...