Dendroclimatological study of Sabina saltuaria and Abies faxoniana in the mixed forests of the Qionglai Mountains,eastern Tibetan Plateau

Tree-ring chronologies were developed for Sabina saltuaria and Abies faxoniana in mixed forests in the Qionglai Mountains of the eastern Tibetan Plateau.Climate-growth relationship analysis indicated that the two co-exist-ing species reponded similarly to climate factors,although S.saltuaria was more sensitive than A.faxoniana.The strong-est correlation was between S.saltuaria chronology and regional mean temperatures from June to November.Based on this relationship,a regional mean temperature from June to November for the period 1605-2016 was constructed.Reconstruction explained 37.3%of the temperature variance during th period 1961-2016.Six major warm periods and five major cold periods were identified.Spectral analysis detected significant interannual and multi-decadal cycles.Reconstruction also revealed the influence of the Atlantic Multi-decadal Oscillation,confirming its importance on climate change on the eastern Tibetan Plateau.

Long-term changes in radial growth of seven tree species in the mixed broadleaf-Korean pine forest in Northeast China:Are deciduous trees favored by climate change?

The role of the temperate mixed broadleaf-Korean pine forest(BKF)in global biogeochemical cycles will depend on how the tree species community responds to climate;however,species-specific responses and vulner-abilities of common trees in BKF to extreme climates are poorly understood.Here we used dendrochronological meth-ods to assess radial growth of seven main tree species(Pinus koraiensis,Picea jezoensis,Abies nephrolepis,Fraxinus mandshurica,Phellodendron amurense,Quercus mongolica,and Ulmus davidiana)in an old-growth BKF in response to climate changes in the Xiaoxing’an Mountains and to improve predictions of changes in the tree species compo-sition.Temperature in most months and winter precipita-tion significantly negatively affected growth of P.jezoensis and A.nephrolepis,but positively impacted growth of P.koraiensis and the broadleaf species,especially F.mandshu-rica and U.davidiana.Precipitation and relative humidity in June significantly positively impacted the growth of most tree species.The positive effect of the temperature during the previous non-growing season(PNG)on growth of F.mandshurica and Q.mongolica strengthened significantly with rapid warming around 1981,while the impact of PNG temperature on the growth of P.jezoensis and A.nephrolepis changed from significantly negative to weakly negative or positive at this time.The negative response of radial growth of P.jezoensis and A.nephrolepis to precipitation during the growing season gradually weakened,and the negative response to PNG precipitation was enhanced.Among the studied species,P.koraiensis was the most resistant to drought,and U.davidiana recovered the best after extreme drought.Ulmus davidiana,P.jezoensis and A.nephrolepis were more resistant to extreme cold than the other species.Climate warming generally exacerbated the opposite growth patterns of conifer(decline)and broadleaf(increase)spe-cies.Deciduous broadleaf tree species in the old-growth BKF probably will gradually become dominant as warming continues.Species-specific growth-climate relationships should be considered in future models of biogeochemical cycles and in forestry management practices.

Effect of thinning intensity on the carbon sequestration of natural mixed coniferous and broadleaf forests in Xiaoxing'an Mountains, China

To study the effect of thinning intensity on the carbon sequestration by natural mixed coniferous and broad-leaf forests in Xiaoxing’an Mountains,China,we established six 100 m×100 m experimental plots in Dongfanghong For-est that varied in thinning intensity:plot A(10%),B(15%),C(20%),D(25%),E(30%),F(35%),and the control sample area(0%).A principal component analysis was performed using 50 different variables,including species diversity,soil fertility,litter characteristics,canopy structure param-eters,and seedling regeneration parameters.The effects of thinning intensity on carbon sequestration were strongest in plot E(0.75),followed by D(0.63),F(0.50),C(0.48),B(0.22),A(0.11),and the control(0.06).The composite score of plot E was the highest,indicating that the carbon sequestration effect was strongest at a thinning intensity of 30%.These findings provide useful insights that could aid the management of natural mixed coniferous and broadleaf forests in Xiaoxing’an Mountains,China.This information has implications for future studies of these forests,and the methods used could aid future ecological assessments of the natural forests in Xiaoxing’an Mountains,China.

Composition and properties of soil humus in a mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum

This study was conducted in Xinkou Experimental Forestry Farm of Fujian Agricultural and Forestry University, Sanming, Fujian Province in January 1999. Taking pure stand of Chinese fir as control, the authors measured and studied the content of organic carbon, content of humic acid (HA), ratio of HA to fulvic acid (FA), and the characteristics of infrared light spectrum and visible light spectrum of soil humus in the mixed forest of Chinese fir and Tsoong?tree. Compared to humus composition in the pure stand of Chinese fir, the content of soil organic C, HA content, and the E4 value of HA for different layers of soil, except for the ratio of HA to FA, showed a significant increase in the mixed forest, while the ratios of E4 to E6 had a little decrease. The infrared light spectrum of humic acid had an absorptive peak at 1650 cm-1. It is concluded that the levels of humification and aromaticity of soil humus are higher in the mixed forest, which is favorable for the improvement of soil structure and nutrient supply, thus improving the soil fertility to a certain degree.

Seasonal Dynamics of Energy Return Through Litterfall of A Mixed Forest of Chinese Fir and T. odorum

Based on the measurement of monthly litterfall and their gross calor ic values, the seasonal dynamics of energy return through litterfall were determ ined in a pure and a mixed T. odorum (Tsoongiodendron odorum Chun) forests with Ch inese fir (Cunninghamia lanceolata (Lamb.) Hook.) in Sanming, Fujian Provinc e. Annual ene rgy return through litterfall was estimated as 12.648×10 6J·m -2 for the mixed fo rest, being 4 2% higher than that of the pure forest, and a large proportion of the energy return comprised leaf litter. The conversion efficiency of solar rad i ation energy into litterfall was 0 56% for mixed forest and 0 54% for pure for es t, respectively. The monthly energy flux in litterfall of Chinese fir showed a t hree-apex curve, peaked in March, August and December, respectively, which was s imilar to that in various fractions of leaf, twig, flower and fruit litter. The consistency in monthly patterns among different litter fractions of Chinese fir was attributed to their solid connections all the while. The monthly energy flux in litterfall of T. odorum culminated in January, May and August, the same was true for its leaf and twig litter. However, energy flux in flower litter only oc curred during March to May and that in fruit litter appeared in January and Marc h. The monthly dynamics of energy flux through litterfall of the two forests wer e both determined by their respective litterfall pattern of Chinese fir. Seasona l energy flux in litterfall for both mixed and pure forests followed the sequenc e of spring>winter>summer>autumn, but fluctuations in the former were less disti nct than those in the latter.

Soil carbon dioxide fluxes of a typical broad-leaved/Korean pine mixed forest in Changbai Mountain, China

The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static closed chamber technique in a typical broad-leaved/Korean pine mixed forest area on the northern slope of Changbai Mountain, Jilin Province, China. The experiment was carried out through the day and night in the growing season (from June to September) in situ and sample gas was analyzed by a gas chromatograph. Results showed that the forest floor was a large net source of carbon, and soil CO2 fluxes had an obvi-ous law of seasonal and diel variation. The soil CO2 flux of broad-leaved/Korean pine mixed forest was in the range of 0.302.42 mmol穖-2穝-1 with the mean value of 0.98 mmol穖-2穝-1. An examination on the seasonal pattern of soil CO2 emission suggested that the variability in soil CO2 flux could be correlated with variations in soil temperature, and the maximum of mean CO2 flux occurred in July ((1.27±23%) mmol穖-2穝-1) and the minimum was in September ((0.50±28%) mmol穖-2穝-1). The fluctuations in diel soil CO2 flux were also correlated with changes in soil temperature; however, there existed a factor for a time lag. Soil CO2 flux from the forest floor was strongly related to soil temperature and had the highest correlation with temperature at 6-cm depth of soil. Q10 values based on air temperature and soil temperature of different soil depths were at the ranges of 2.09–3.40.

Dynamics of nitrogen and phosphorus concentrations of fine roots in a mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum

From September 1999 to July 2000, N and P concentrations of fine roots were measured with the method of sequential soil core at bimonthly intervals in a mixed forest of Tsoong's tree (Tsoongiodendron odorum Chun) and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) in Sanming, Fujian. The results showed that N, P concentration of Chinese fir and Tsoong's tree in fine roots were negatively related to root diameter size. The concentrations of N and P in living roots and dead roots were compared. The order of N concentration in fine roots in different samples was Tsoong's tree>undergrowth>Chinese fir, while that of P was undergrowth>Tsoong's tree>Chinese fir. For Chinese fir, the seasonal change of N, P concentrations in fine roots with various diameter classes showed a single-apex curve with a maximum in September. For Tsoong's tree, maximized concentration of N in fine roots appeared in July or September and maximized P concentration in May.

Effect of Mixed Forests of Chinese Fir and Tsoong's Tree on Soil Properties

An investigation and on 13 year old (1984～1996) Chinese fir and Tsoong's tree mixed forests in Jianou City, Fujian Province, China was carried out to compare the influences of different interplanting types of individual tree tree, row row, row strip (three rows) and pure Chinese fir stands on soil properties. Compared with the pure stands of Chinese fir, the mixed stands exerted a positive effect on soil fertility, with increases in soil organic matter, total N, available P and available K. Moreover, improvements were also observed in soil enzymatic activities, aggregate structure, structure stability, status of soil porosity, soil aeration and penetrability in mixed stands. The row row interplanted stands had the best effect on tree growth and soil properties among these mixed forests. In the southern subtropical region, the spreading of the row row mixing model of the two tree species would be helpful to preventing the soil from fertility deterioration caused by successive plantation of Chinese fir.

Local and generalized height-diameter models with random parameters for mixed,uneven-aged forests in Northwestern Durango,Mexico

Background:We used mixed models with random components to develop height-diameter(h-d) functions for mixed,uneven-aged stands in northwestern Durango(Mexico),considering the breast height diameter(d) and stand variables as predictors.Methods:The data were obtained from 44 permanent plots used to monitor stand growth under forest management in the study area.Results:The generalized Bertalanffy-Richards model performed better than the other generalized models in predicting the total height of the species under study.For the genera Pinus and Quercus,the models were successfully calibrated by measuring the height of a subsample of three randomly selected trees close to the mean d,whereas for species of the genera Cupressus,Arbutus and Alnus,three trees were also selected,but they are specifically the maximum,minimum and mean d trees.Conclusions:The presented equations represent a new tool for the evaluation and management of natural forest in the region.

Distribution Patterns and Associations of Dominant Tree Species in a Mixed Coniferous-Broadleaf Forest in the Changbai Mountains

In 2012 a plot was established with 1-ha area in a mixed coniferous-broadleaf forest in the Changbai Mountains, northeastern China for examining local forest processes, structure and succession. A method of O-ring statistics （pair- correlation function） was applied to analyze the spatial patterns and associations of the dominant species within different vertical layers. After the evaluation by their importance values, six tree species （or group） （i.e. Abies nephrolepis, Picea jezoensis, Pinus koraiensis, Tilia amurensis, and species group of Betula ssp. and species group of Acer ssp.） were determined as dominant trees species. It was found that some of these species exhibited closely clustered distributions at fine distances. As spatial distance increased, a random or even regular distribution gradually appeared with the exception of the upper layers of A. nephrolepis and P. koraiensis, and the lower layers of P. jezoensis, P. koraiensis and Betula ssp., which were substantially randomly distributed. Intra- and inter-species spatial associations varied in accordance with species, tree height and reciprocal distances. Positive associations were observed between the lower and upper height classes of trees of the same species （except for that of P. jezoensis） at fine distances. This may be owing to limited seed dispersal and geological heterogeneity. The aggregation intensity declines with increasing distances and this consistent with the predictions of self-thinning. Some coniferous trees （e.g. Pinus koraiensis） in the lower height class were positively associated with T. amurensis and group of Betula ssp. of the upper height class at some distances, suggesting that saplings of coniferous trees occupy a broader niche and can grow well under the canopy of the adult of broad-leaved trees. Negative associations were observed between upper coniferous trees and lower broad-leaved trees and between upper P. jezoensis and lower P. koraiensis, suggesting that a canopy of these trees might not provide suitable environment for the survival, establishment, and growth of o lower individuals, corresponding well to Janzen-Connell hypothesis.

Root secretion stimulating ash growth in larch-ash mixed forest

Allelopathic effect of larch (Larix gmelini ) on the ash growth (Fraximus mandshurica) was studied in artificial cultivation tests. The results revealed that the larch root secretion obviously stimulated the ash growth. In order to determine the main stimulation allelochemicals, the chemical composition was analyzed. By contrasting the contents of carbohydrate and aminoacid in root secretion of larch and ash, it was concluded that the carbohydrate and aminoacid were not important stimulation allelochemicals. The organic acid and other components in root secration of larch and ash were analyzed by GC and GC-MS analysis. The sand culture tests were carried out ed selected model compounds. The results showed that benzeneacetic acid, benzenepropionic acid and phenolic acids in root secretion of larch were the main stimulation allelochemicals.

Forest structure and carbon dynamics of an intact lowland mixed dipterocarp forest in Brunei Darussalam

Tropical forests play a critical role in mitigating climate change because they account for large amount o terrestrial carbon storage and productivity.However,there are many uncertainties associated with the estimation o carbon dynamics.We estimated forest structure and carbon dynamics along a slope（17.3°–42.8°）and to assess the relations between forest structures,carbon dynamics,and slopes in an intact lowland mixed dipterocarp forest,in Kuala Belalong,Brunei Darussalam.Living biomass,basa area,stand density,crown properties,and tree family composition were measured for forest structure.Growth rate,litter production,and litter decomposition rates were also measured for carbon dynamics.The crown form index and the crown position index were used to assess crown properties,which we categorized into five stages,from very poor to perfect.The living biomass,basal area and stand density were 261.5–940.7 Mg ha-1,43.6–63.6 m2ha-1and 6,675–8400 tree ha-1,respectively.The average crown form and position index were 4,which means that the crown are mostly symmetrical and sufficiently exposed for photosynthesis.The mean biomass growth rate,litter production,litter decomposition rate were estimated as11.9,11.6 Mg ha-1a-1,and 7.2 g a-1,respectively.Biomass growth rate was significantly correlated with living biomass,basal area,and crown form.Crown form appeared to strongly influence living biomass,basal area and biomass growth rate in terms of light acquisition.However,basal area,stand density,crown properties,and biomass growth rate did not vary by slope or tree family composition.The results indicate that carbon accumulation by tree growth in an intact lowland mixed dipterocarp forest depends on crown properties.Absence of any effect of tree family composition on carbon accumulation suggests that the main driver of biomass accumulation in old-growth forests of Borneo is not species-specific characteristics of tree species.

Nutrient cycling characteristics of Quercus acutissima and Pinus massoniana mixed forest in the Three Gorge Reservoir area, China

The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 878, 725 and 117 times of inside cycling coefficients of N, P and K, respectively. 3392, 1026 and 1588 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 1431, 132 and 1048 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 549%, 130%, and 834% of N, P and K withdraw from leaves to branches, 499%, 199% and 730% of N, P and K withdraw from branches to trunks per year, respectively.

Effects of Logging Intensity on Structure and Composition of a Broadleaf-Korean Pine Mixed Forest on Changbai Mountains,Northeast China

In order to identify a harvesting model which is beneficial for broadleaf-Korean pine mixed forest （BKF） sustainability, we investigated four types of harvested stands which have been logged with intensities of 0 （T0, control）, 15% （T1, low intensity）, 35% （T2, moderate intensity）, and 100% （T3, clear-cutting）, and examined the impacts of logging intensity on composition and structure of these stands. Results showed that there were no significant differences between To and T1 for all structural characteristics, except for density of seeding and large trees. The mean diameter at breast height （DBH, 1.3 m above the ground）, stem density and basal area of large trees in T2 were significantly lower than in To, while the density of seedlings and saplings were significantly higher in T2 than in To. Structural characteristics in T3 were entirely different from To. Dominant tree species in primary BKF comprised 93%, 85%, 45% and 10% of the total basal area in T0, T1, T2 and T3, respectively. Three community similarity indices, the Jaccard＇s similarity coefficient （Cj）; the Morisita-Hom index （CMH）; and the Bray-Curtis index （CN）, were the highest for T0 and T1, followed by T0 and T2, and T0 and T3, in generally. These results suggest that effects of harvesting on forest composition and structure are related to logging intensities. Low intensity harvesting is conductive to preserving forest structure and composition, allowing it to recover in a short time period. The regime characterized by low logging intensity and short rotations appears to be a sustainable harvesting method for BKF on the Changbai Mountains.

Effect of thinning intensity on understory herbaceous diversity and biomass in mixed coniferous and broad-leaved forests of Changbai Mountain

Background:Herbs are an important part of the forest ecosystem,and their diversity and biomass can reflect the restoration of vegetation after forest thinning disturbances.Based on the near-mature secondary coniferous and broad-leaved mixed forest in Jilin Province Forestry Experimental Zone,this study analyzed seasonal changes of species diversity and biomass of the understory herb layer after different intensities of thinning.Results:The results showed that although the composition of herbaceous species and the ranking of importance values were affected by thinning intensity,they were mainly determined by seasonal changes.Across the entire growing season,the species with the highest importance values in thinning treatments included Carex pilosa,Aegopodium alpestre,Meehania urticifolia,and Filipendula palmata,which dominated the herb layer of the coniferous and broad-leaved mixed forest.The number of species,Margalef index,Shannon-Wiener index and Simpson index all had their highest values in May,and gradually decreased with months.Pielou index was roughly inverted“N”throughout the growing season.Thinning did not increase the species diversity.Thinning can promote the total biomass,above-and below-ground biomass.The number of plants per unit area and coverage were related to the total biomass,above-and below-ground biomass.The average height had a significantly positive correlation with herb biomass in May but not in July.However,it exerted a significantly negative correlation with herb biomass in September.The biomass in the same month increased with increasing thinning intensity.Total herb biomass,above-and below-ground biomass showed positive correlations with Shannon-Winner index,Simpson index and Pielou evenness index in May.Conclusions:Thinning mainly changed the light environment in the forest,which would improve the plant diversity and biomass of herb layer in a short time.And different thinning intensity had different effects on the diversity of understory herb layer.The findings provide theoretical basis and reference for reasonable thinning and tending in coniferous and broad-leaved mixed forests.

Dynamics of nitrogen nutrition of coexisting dominant trees in mixed broad-leaved/Korean pine forest

Chemical analysis of ammonium, nitrate and total nitrogen in tree leaves and roots and anin-vivo bioassay for nitrate reductase activity (NRA) were used to monitor the seasonal variations in nitrogen assimilation among four coexisting dominant tree species, includingPinus koraiensis, Tilia amurensis, Fraxinus mandshurica andAcer mono, in a virgin mixed broad-leaved/Korean pine (Pinus koraiensis) forest. The soil study included individual horizons of L+F (0–5 cm), Ah (5–11 cm) and Aw (11–25 cm). All four species had nitrate and ammonium in their roots and leaves, and also NRA in leaves. This indicated that these coexisting species were adapted to ammonium + nitrate nutrition. A negative correlation existed between nitrate use and ammonium use. Ammonium concentration was higher than that of nitrate in tree leaves and roots, and also in soils, which indicated climax woody species had a relative preference for ammonium nutrition. There was a positive relationship between tree nitrogen nutrition use and soil nitrogen nutrient supply. Utilization of ammonium and nitrate as well as the seasonal patterns differed significantly between the species. Peaks of ammonium, nitrate, NRA and total nitrogen in one species were therefore not necessarily synchronous with peaks in other species, and which indicated a species-specific seasonal use of nitrogen. The species-specific temporal differentiation in nitrogen use might reduce the competition between co-existing species and may be an important mechanism promoting stability of virgin mixed broad-leaved//Korean pine forest.

NITROGEN NUTRIENT MECHANISM IN SECONDARY SUCCESSION PROCESS OF THE MIXED BROAD-LEAVED/ KOREAN PINE (PINUS KORAIENSIS) FOREST

Chemical and biochemical analysis methods were used to monitor the vedations of nitrogen nutrient among the dominance trees species in secondary succession process of the mixed broad - leaved/Korean pine forest on Changbai Mountains, Northeast China. Amounts of total nitrogen, anunonium and NRA in soils of virgin broad-leaved/Korean pine forest which is in climax were higher than those of secondary birch forests those are in succession Stage. The amount of nitrate was in the other hand. In climax, dominance trees species are tolerant mesophytic trees such as Pinus Koraiensis, Tilia amurensis, Acer mono and also Fraxinus mandshurica, they are all ammonium + nitrate adapted species, but they show a preference for the anunonium rather than those of the pioneer trees species in secondary birch forest, such as Populus davidiava and Betula platyphylla. Because they have more ammonium in their leaves and roots, especially Pinus koraiensis. Populus davidvana and Betula plaaphlla are intolerant trees, amounts of nitrate and total nitrogen is higher in their leaves and roots and also NRA in their leaves, so they preference for the nitrate rather than the others.In secondary birch forest, the regeneration trees species adapt their nitroggn nutrient to the variation of nitrogen nutrient situation in soil, finally they could survival well and the secondary birch forest would succession to climax. In climax, dominance trees species adapt their Nitrogen nutrient to the situation in soil and there are not strong competition in nitrogen nutrient among them, so they can coexist well and keep the climax as stable vegetation.

Topography and soil content contribute to plant community composition and structure in subtropical evergreen-deciduous broadleaved mixed forests

Topography and soil factors are known to play crucial roles in the species composition of plant communities in subtropical evergreen-deciduous broadleaved mixed forests.In this study,we used a systematic quantitative approach to classify plant community types in the subtropical forests of Hubei Province(central China),and then quantified the relative contribution of drivers responsible for variation in species composition and diversity.We classified the subtropical forests in the study area into 12 community types.Of these,species diversity indices of three communities were significantly higher than those of others.In each community type,species richness,abundance,basal area and importance values of evergreen and deciduous species were different.In most community types,deciduous species richness was higher than that of evergreen species.Linear regression analysis showed that the dominant factors that affect species composition in each community type are elevation,slope,aspect,soil nitrogen content,and soil phosphorus content.Furthermore,structural equation modeling analysis showed that the majority of variance in species composition of plant communities can be explained by elevation,aspect,soil water content,litterfall,total nitrogen,and total phosphorus.Thus,the major factors that affect evergreen and deciduous species distribution across the 12 community types in subtropical evergreendeciduous broadleaved mixed forests include elevation,slope and aspect,soil total nitrogen content,soil total phosphorus content,soil available nitrogen content and soil available phosphorus content.

Floristic Composition, Structure and Soil Properties of Mixed Deciduous Forest and Deciduous Dipterocarp Forest: Case Study in Madan Watershed, Myanmar

Patterns of woody regeneration in terms of species composition and diversity were studied in mixed deciduous forest (MDF) and deciduous dipterocarp forest (DDF) in Minbyin reserved forest of Lewe Township. A total of 57 plant species of MDF belonging to 28 families and 342 individuals and 25 plant species of DDF consist of 15 families and 285 individuals were identified. Plant species diversity was quantitatively higher in the MDF (H' = 3.68) compared to the DDF (H' = 2.39). Tectona grandis showed the highest density (30), dominance (4.40 m2) and IVI (27.01) of MDF and Dipterocarpus tuberculatus also composed the highest density (109), dominance (9.02 m2) and IVI (81.87) in DDF. The smallest diameter class (10 - 20 cm) comprised with 29 species, 103 individuals in MDF and 18 species, 85 individuals in DDF. The size class distribution displayed a reverse J-shaped pattern. The largest numbers of species were concentrated in the smallest height class in both investigated forests because of height and diameter distribution is closely related. The total densities of seedlings and saplings were 1219 and 531 ha-1 in MDF and 988 and 444 ha-1 in DDF respectively. Although soil texture of (40 - 50 cm) and (90 - 100 cm) were sandy clay loam in mixed deciduous forest, the other layers of both investigated forests were sandy loam.

Analysis of forest structural complexity using airborne LiDAR data and aerial photography in a mixed conifer–broadleaf forest in northern Japan

Determining forest structural complexity,i.e.,a measure of the number of different attributes of a forest and the relative abundance of each attribute,is important for forest management and conservation.In this study,we examined the structural complexity of mixed conifer–broadleaf forests by integrating multiple forest structural attributes derived from airborne Li DAR data and aerial photography.We sampled 76 plots from an unmanaged mixed conifer–broadleaf forest reserve in northern Japan.Plot-level metrics were computed for all plots using both field and remote sensing data to assess their ability to capture the vertical and horizontal variations of forest structure.A multivariate set of forest structural attributes that included three Li DAR metrics(95 th percentile canopy height,canopy density and surface area ratio) and one image metric(proportion of broadleaf cover),was used to classify forest structure into structural complexity classes.Our results revealed significant correlation between field and remote sensing metrics,indicating that these two sets of measurements captured similar patterns of structure in mixed conifer–broadleaf forests.Further,cluster analysis identified six forest structural complexity classes includingtwo low-complexity classes and four high-complexity classes that were distributed in different elevation ranges.In this study,we could reliably analyze the structural complexity of mixed conifer–broadleaf forests using a simple and easy to calculate set of forest structural attributes derived from airborne Li DAR data and high-resolution aerial photography.This study provides a good example of the use of airborne Li DAR data sets for wider purposes in forest ecology as well as in forest management.