[Critical influencing factors on vegetation productivity in sandy land of the Northwestern Liaoning Province,China]. / è¾½è¥¿åŒ—æ²™åŒ–åœŸåœ°æ¤è¢«ç”Ÿäº§åŠ›å ³é”®å½±å“å› ç´ .

To reveal the key factors influencing vegetation productivity in sandy lands, we conducted a comprehensive analysis of vegetation productivity on regional scale, pixel scale, and plot scale of the sandy lands in northwes-tern Liaoning Province, based on soil physicochemical data, topographical data, climate data, and the intrinsic characteristics of vegetation. On the regional scale, we established a random forest model to explore the impact of topographical factors, climate factors, and vegetation characteristics on vegetation productivity. On the pixel scale, we performed a correlation analysis between vegetation cover and climate factors. On the plot scale, we combined the physicochemical properties of 234 soil samples with topographical factors and vegetation characteristics, and utilized the random forest model to calculate the importance values of each factor. The results showed that soil nutrients could explain 24.8% of the spatial variation in net primary productivity when other factors were excluded. When introducing topographical factors into the model, the model could explain 40% variation of net primary productivity. When further incorporating fractional vegetation coverage and leaf area index into the model, the model could explain 72.8% variation of net primary productivity. Our findings suggested that fractional vegetation coverage and leaf area index were the most influential factors affecting vegetation productivity in this area. Topographical factors ranked second, followed by climate factors, which had a relatively small impact.

[Latitudinal variations of seed functional traits of Phragmites australis in Chinese coastal marsh]. / 中国滨海沼泽湿地芦苇种子功能性状的纬度梯度变异.

Functional traits of seeds reflect plant reproductive strategies adapting to environmental changes, which is an evolutionary behavior in natural selection and genetics. Study on seed functional traits is of great significance to deeply understand the long-term adaptive evolution of plants and seeds. We measured seed functional traits of a main indigenous species Phragmites australis, including seed size, seed weight, seed set, and seed production, in nine coastal marshes of the six provinces/cities along the coastal zone of China (21°29'-40°57' N), and analyzed latitudinal variations of functional traits. The results showed that seed functional traits of P. australis in Chinese coastal marshes varied significantly with latitude and that there were significant correlations among different traits. Seed size (including seed length, seed width, seed shape index, aspect ratio, and seed surface area), and 100-seed weight showed significant quadratic function relation with latitude, which firstly decreased and then increased with the increases of latitude, while seed setting rate firstly increased and then reduced. There was a trade-off between the number and size of P. australis seeds. Seed production per unit area significantly increased with latitude. Results of stepwise regression analysis showed that climatic factors were the main driver resulting in the difference of seed functional traits of P. australis between latitudes, followed by pH and salinity of soil porewater.

Temperature sensitivity of SOM decomposition is linked with a K-selected microbial community.

Temperature sensitivity (Q10 ) of soil organic matter (SOM) decomposition is a crucial parameter to predict the fate of soil carbon (C) under global warming. Nonetheless, the response pattern of Q10 to continuous warming and the underlying mechanisms are still under debate, especially considering the complex interactions between Q10 , SOM quality, and soil microorganisms. We examined the Q10 of SOM decomposition across a mean annual temperature (MAT) gradient from -1.9 to 5.1°C in temperate mixed forest ecosystems in parallel with SOM quality and bioavailability, microbial taxonomic composition, and functional genes responsible for organic carbon decomposition. Within this temperature gradient of 7.0°C, the Q10 values increased with MAT, but decreased with SOM bioavailability. The Q10 values increased with the prevalence of K-strategy of soil microbial community, which was characterized by: (i) high ratios of oligotrophic to copiotrophic taxa, (ii) ectomycorrhizal to saprotrophic fungi, (iii) functional genes responsible for degradation of recalcitrant to that of labile C, and (iv) low average 16S rRNA operon copy number. Because the recalcitrant organic matter was mainly utilized by the K-strategists, these findings independently support the carbon quality-temperature theory from the perspective of microbial taxonomic composition and functions. A year-long incubation experiment was performed to determine the response of labile and recalcitrant C pools to warming based on the two-pool model. The decomposition of recalcitrant SOM was more sensitive to increased temperature in southern warm regions, which might attribute to the dominance of K-selected microbial communities. It implies that climate warming would mobilize the larger recalcitrant pools in warm regions, exacerbating the positive feedback between increased MAT and CO2 efflux. This is the first attempt to link temperature sensitivity of SOM decomposition with microbial eco-strategies by incorporating the genetic information and disentangling the complex relationship between Q10 and soil microorganisms.

Soil pH and plant diversity shape soil bacterial community structure in the active layer across the latitudinal gradients in continuous permafrost region of Northeastern China.

In the permafrost region of northeastern China, vegetation and soil environment have showed response to permafrost degradation triggered by global warming, but the corresponding variation of the soil microbial communities remains poorly investigated. Here, a field investigation in the continuous permafrost region was conducted to collect 63 soil samples from 21 sites along a latitudinal gradient to assess the distribution pattern of microbial communities and their correlation with environmental factors. High-throughput Illumina sequencing revealed that bacterial communities were dominated by Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria. Both microbial richness and phylogenetic diversity decreased initially and then increased as the latitude increased. UniFrac analysis of microbial communities detected significant differences among latitudes. Variation partitioning analysis and structural equation models revealed that environmental variables, including geographic factors, plant-community factors and soil physicochemical factors, all played non-negligible roles in affecting the microbial community structures directly or indirectly. Redundancy analysis and boosted regression tree analysis further highlighted the influences of soil pH and plant richness on microbial community compositions and diversity patterns. Taken together, these results suggest that the distribution pattern of soil microbial communities shows distinct changes along the latitudinal gradients in northeastern China and is predominantly mediated by soil pH and plant diversity.

Data in support of environmental controls on the characteristics of mean number of forest fires and mean forest area burned (1987-2007) in China.

Fire frequency and size are two important parameters describing fire characteristics. Exploring the spatial variation of fire characteristics and understanding the environmental controls are indispensable to fire prediction and sustainable forest landscape management. To illustrate the spatial variation of forest fire characteristics over China and to quantitatively determine the relative contribution of each of the environmental controls to this variation, forest fire characteristic data (mean number of forest fires and mean burned forest area) and environmental data (climate, land use, vegetation type and topography) at provincial level were derived. These data sets can potentially serve as a foundation for future studies relating to fire risk assessment, carbon emission by forest fires, and the impact of climate change on fire characteristics. This data article contains data related to the research article entitled "Environmental controls on the characteristics of mean number of forest fires and mean forest area burned (1987-2007) in China" by chang et al. [1].

Predicting impacts of climate change on the aboveground carbon sequestration rate of a temperate forest in northeastern China.

The aboveground carbon sequestration rate (ACSR) reflects the influence of climate change on forest dynamics. To reveal the long-term effects of climate change on forest succession and carbon sequestration, a forest landscape succession and disturbance model (LANDIS Pro7.0) was used to simulate the ACSR of a temperate forest at the community and species levels in northeastern China based on both current and predicted climatic data. On the community level, the ACSR of mixed Korean pine hardwood forests and mixed larch hardwood forests, fluctuated during the entire simulation, while a large decline of ACSR emerged in interim of simulation in spruce-fir forest and aspen-white birch forests, respectively. On the species level, the ACSR of all conifers declined greatly around 2070s except for Korean pine. The ACSR of dominant hardwoods in the Lesser Khingan Mountains area, such as Manchurian ash, Amur cork, black elm, and ribbed birch fluctuated with broad ranges, respectively. Pioneer species experienced a sharp decline around 2080s, and they would finally disappear in the simulation. The differences of the ACSR among various climates were mainly identified in mixed Korean pine hardwood forests, in all conifers, and in a few hardwoods in the last quarter of simulation. These results indicate that climate warming can influence the ACSR in the Lesser Khingan Mountains area, and the largest impact commonly emerged in the A2 scenario. The ACSR of coniferous species experienced higher impact by climate change than that of deciduous species.

[Simulating climate change effect on aboveground carbon sequestration rates of main broadleaved trees in the Xiaoxing'an Mountains area, Northeast China].

LANDIS Pro 7.0 model was used to simulate the dynamics of aboveground biomass of ten broadleaved tree species in the Xiao Xing' an Mountains area under current and various climate change scenarios from 2000 to 2200, and carbon content coefficients (CCCs) were coupled to cal- culate the aboveground carbon sequestration rates (ACSRs) of these species. The results showed that in the initial year of simulation, the biomasses and their proportions of Fraxinus mandshurica, Phellodendron amurense, Quercus mongolica, Ulmus propinqua, and Acer mono were relatively low, while those of Betula costata, Betula platyphylla, and Populus davidiana were higher. A trend of rise after decline occurred in ACSR for pioneer species in the mid and late periods of simulation years, but ACSRs for the other broadleaved tree species were considerably complex. The ACSRs of Q. mongolica and Tilla amurensis fluctuated in the ranges of -0.05-0.25 t · hm(-2) · 10 a(-1) and 0.16-1.29 t · hm(-2) · 10 a(-1) in simulation years, respectively. The ACSRs of F. mandshurica, U. propinqua, A. mono, and B. costata showed a trend of decline after rise in late simulation years. There were significant differences in ACSR for P. amurense and B. davurica among various climate change scenarios in the periods of 2050-2100 and 2150-2200, while no significant difference in ACSR for the other species would be detected. Difference of sensitivity of various species in ACSR for future climate scenarios in the Small Khingan Mountains area existed. However, the un- certainty of future climates would not yield significant difference in ACSR for most broadleaved tree species. Moreover, a time lag would exist in the process of climate change effects on temperate forest's ACSR.

[Effects of forest ownership regime on landscape pattern and animal habitat: a review].

In some European and North American countries where forestry is highly developed, both public and private forest ownership regimes have being existed for a long time. Currently, the researches about both the dynamics of forest landscape and habitat pattern and the relationship between habitat pattern and biological conservation in multi-ownership forest landscape are increasingly becoming important. This paper reviewed the effects of multi-ownership regime on forest landscape pattern and animal habitat and emphasized on the ecological consequences of forest parcelization and land divestiture, including the provision of diverse habitats and fragmentation of the existing large-area habitat. This paper also summarized two ways (changing the ownership pattern and integrating the multi-ownership management by cross boundary coordination) for handling the conflicts between small-scaled multi-ownership management and biological conservation at large scale in forestry-developed countries and analyzed the reasons that those countries prefer to adopt the latter one. Furthermore, the methodological limitations in simulating ownership pattern were pointed out. Finally, the present status, challenges and opportunities in the above-mentioned research issues in China were discussed, and the suggestions for further researches were provided.

[Effects of spatial heterogeneity on spatial extrapolation of sampling plot data].

By using model combination method, this paper simulated the changes of response variable (tree species distribution area at landscape level under climate change) under three scenarios of environmental spatial heterogeneous level, analyzed the differentiation of simulated results under different scenarios, and discussed the effects of environmental spatial heterogeneity on the larger spatial extrapolation of the tree species responses to climate change observed in sampling plots. For most tree species, spatial heterogeneity had little effects on the extrapolation from plot scale to class scale; for the tree species insensitive to climate warming and the azonal species, spatial heterogeneity also had little effects on the extrapolation from plot-scale to zonal scale. By contrast, for the tree species sensitive to climate warming, spatial heterogeneity had effects on the extrapolation from plot scale to zonal scale, and the effects could be varied under different scenarios.

[Interaction between pest and fire disturbances in Huzhong area of Great Xing' an Mountains: long-term simulation].

Forest pest and forest fire are the two major disturbances of forest ecosystem, and there exists definite interaction between the disturbances at large spatial and temporal scales. In this paper, the spatially intuitional landscape model (LANDIS) was adopted to simulate the long-term (300 years) interaction between forest pest and forest fire in Huzhong area of Great Xing' an Mountains. The results showed that pest disturbance decreased the fine fuel load, increased the coarse fuel load at the early (0-100 a) and middle (100-200 a) stages of simulation course, and decreased the fire frequency at the early and middle stages. The fire frequency under different forest pest disturbance scenarios was similar at the later stage (200-300 a) of simulation course. Pest disturbance decreased the fire intensity and fire risk class at the early and later stages, but increased the fire intensity and fire risk class at the middle stage. Fire suppression could increase the occurrence area of forest pest, and thus, it was suggested that forest managers should take appropriate measures to prevent insect pest, not solely with the focus on fire suppression but also adopting the forest fire management measures such as taking off coarse fuel and implementing prescribed fire to ensure the sustainable development of forest ecosystem.

[Simulation of timber-harvesting area in Xiao Xing' anling Mountains under climate change].

By using the spatially explicit forest landscape model (LANDIS 6.0 PRO), the percentages of timber-harvesting area in Xiao Xing' anling Mountains under current harvesting scenario and under 11 harvesting scenarios with alternating harvesting intensities (alternating time was 10, 20 and 30 years, respectively) in 2000-2400 under climate change were simulated. Alternating harvesting intensity could increase the harvesting area. Comparing with current harvesting scenario, the simulated scenarios could increase the harvesting area by 3%-5% at short term (10-30 years), 2.5%-7% at medium term (40-60 years), and 3.5%-8% at long term (70-100 years). On the whole, the current total harvesting area was still high. Alternating harvesting-intensity could increase the harvesting area within a definite term, but the effect would be unsustainable. To have a sustainable development of forestry in the study area, it is necessary to reduce the harvesting intensity and change the forest management policy.

[Effects of eco-protection policy on land use/cover in upper reaches of Minjiang River].

By using CLUE-S model, a scenario analysis was made on the land use/cover change in the upper reaches of Minjiang River from 2000 to 2020, based on the historic development trend and the regulations of policies "natural forest protection" and "grain for green". In 2000-2020, according to the historic development trend, the forestland area (landscape matrix) in the study region would have a continual decrease while the shrub land and grassland areas would be increased, and the landscape pattern would be more fragmental. The implementation of the policies "natural forest protection" and "grain for green" would effectively increase forestland area, being able to reverse the trend of landscape fragmentation and more optimize the landscape pattern.

[Long-term effects of Dendrolimus superans Bulter disturbance on forest landscape in Huzhong Forest Bureau of Great xing' an Mountains: a simulation study].

A spatially explicit landscape model LANDIS was applied to simulate the long-term effects of Dendrolimus superans Bulter disturbance on the forest landscape in Huzhong Forest Bureau of Great Xing' an Mountains. The statistical software pakage APACK was used to calculate the distribution area of D. superans and representative tree species, the aggregation index reflecting the spatial pattern, and the average area of forest patchs. The dynamics of forest landscape in the study region was simulated under two scenarios, i.e., with and without D. superans disturbance for 300 years (from 1990 to 2290). In the region, the distribution area of D. superans showed a trend of increased first and decreased then. Under D. superans disturbance scenario, the distribution area and the average patch size of Larix gmelinii in 0-150 years and the aggregation index of L. gmelinii in 0-190 years, the distribution area and the average patch size of Betula platyphylla and its aggregation index in 80-190 years, as well as the distribution area, average patch size, and aggregation index of Pinus sylvestris var. mongolica were lower or slightly lower than those under no disturbance scenario. D. superans disturbance led to the fragmentation of forest landscape to some extent.

[Soil respiration of degraded Korean pine forest ecosystem in Changbai Mountains].

Taking the broad-leaved Korean pine forest area in Changbai Mountains, a typical eastern forest belt of Northeast China for global change as test object, and by using the approaches of trenching-plot and infrared gas exchange analyzer, this paper analyzed the soil respiration in a selected series of degraded Korean pine forest ecosystem, i.e., broad-leaved Korean pine forest (CK), poplar-birch forest (Y), hardwood forest (S), Mongolian oak forest (M), and bare land (L). In the growth season of the forests, soil respiration showed a clear single peak curve, with the maximum in July or August. The soil respiration decreased in the sequence of Y>M>CK>S>L. The amount of CO2 release in Y and M was about 0.4 and 0.3 times higher than that in CK; and that in S and L accounted for 88% and 78% of CK, respectively.

[Effect zone of forest road on plant species diversity in Great Hing 'an Mountains].

Forest road has far-reaching effects on plant species diversity across varying scales, and the estimation of its effect distance and effect zone is a key issue to integrate the road effect and ecological processes in forest area. In this paper, ten transects, 2 m wide and extending 50 m from varying grade roads including main road, main line for wood transportation, and secondary line for wood transportation in Huzhong forest area of Great Hing' an Mountains were set. The plant composition was investigated in twenty-five 2 m x 2 m plots of each transect. The road-effect distance on plant species diversity identified by moving window analysis in terms of the important value of each plot. The results showed that in study area, the effect distance reached up to 20-34 m, regardless of the roads grade. The plant species diversity of shrub stratum and herb stratum within the effect zone was greater than that in adjacent habitat, with the Shannon-Weiner index increased by 21% and 60%, respectively. The response of shrub stratum to the road effect was more stable than herb stratum, but no significant change was observed in tree stratum. Chamaenerion angustifolium was the indicative species of road-effect zone communities. Based on the estimation of road-effect distance, the road area in Huzhong Forestry Bureau and Great Hing' an Mountains occupied about 0.10%, and its effect zone on vegetation occupied 1.79% and 1.53%, respectively.

[Modeling of forest landscape change in Xiaoxinganling mountains under different planting proportions of coniferous and broadleaved species].

With spatially explicit landscape model (LANDIS), the dynamic change of forest landscape in Youhao Forest Bureau in Xiaoxinganling Mountains from 2001-2201 under 5 planting proportions of coniferous and broadleaved species, i.e., 100% broadleaved species, 70% broadleaved and 30% coniferous species, 50% broadleaved and 50% coniferous species, 30% broadleaved and 70% coniferous species, and 100% coniferous species, was studied, taking the forest under natural regeneration after harvesting as the control. The results showed that afforestation effectively promoted the recovery of forest resources, but single planting of coniferous species would lead to the area percent of broadleaved species lower than the control. When broadleaved species were planted only, the area percent of coniferous species was lower than the control. The area percent and aggregation index of Pinus koraiensis and Larix gmelini increased with increasing planting proportion of coniferous species, and those of Quercus mongolica increased with increasing planting proportion of broad-leaved species. Afforestation decreased the area percent of Betula phatyphylla, but had no significant effects on its aggregation index. Different afforestation strategies not only altered the species area percent, but also affected the species spatial pattern.

[Effects of different forest management alternatives on Sciurus vulgaris habitat].

A spatially explicit landscape model LANDIS was applied to simulate the forest landscape changes under four management alternatives (no cutting, clear cutting, selective cutting I and II) in Youhao Forestry Bureau located in Small Xing' an Mountain from 2000 to 2200. The outcomes from LANDIS were combined with a landscape-level habitat suitability index (HSI) model in a GIS environment to assess Sciurus vulgaris habitat quality. The results showed that the increase of suitable habitat area and the decrease of marginally suitable area were the fastest under no cutting scenario, and the slowest under clear cutting scenario. Suitable habitat area increased faster while marginally suitable area decreased more slowly under selective cutting I scenario than under selective cutting II. Overall, the optimal management alternative of S. vulgaris habitat was in the sequence of no cutting, selective cutting I, selective cutting II, and clear cutting.

[Dynamics and influence width of dry valley landscape boundary in upper reaches of Minjiang River].

Based on RS and GIS techniques, the distribution extent of the dry valley in upper reaches of Minjiang River was determined, with the dynamics and influence width of its landscape boundary analyzed. The results indicated that the dry valley had a gradually expanded distribution, and the total length of its boundary was increased. The boundary complexity increased from 1974 to 1995 but decreased from 1995 to 2000, and the upper boundary of the dry valley ascended rapidly along mountain slope. The uppermost elevation of the dry valley boundary was 3128 m in 1974, 3167 m in 1995, and 3181 m in 2000. In the last 26 years, the upper boundary of the dry valley ascended 53 m in total, being about 2 m per year. The influence width of the dry valley boundary was 800 m, which could be regarded as a buffer zone to disturbances. The area between 800-1200 m from the dry valley boundary to exterior was a transition zone intensely influenced by the dry valley and its surrounding landscape, which should be addressed in the restoration of the dry valley.

[Landscape change and its spatial driving force of farmlands in Wenchuan County of Min-jiang River upper reach].

Based on remote sensing images and geographic information system, and by using landscape metrics and Kappa coefficient, this paper studied the farmland landscape change in Wenchuan County of Minjiang River upper reach. A logistic regression model was used to analyze the driving forces of this change, with elevation, gradient, aspect, and the distances to road, river and settlement as the affecting factors. The results showed that from 1974 to 2000, the farmland area in Wenchuan County kept increasing, with the greatest increment in 1974-1986. In 1986-2000, farmland area had no evident increase, but converted with other landscape types frequently and had an evident spatial position change, especially in the period from 1994 to 2000. Such a farmland change was mainly driven by policy, and the spatial driving forces differed in different periods.

[Spatiotemporal pattern and its driving forces of urban growth in Shenyang City].

By using time series Landsat TM satellite images and adopting GIS spatial analysis and landscape pattern analysis methods, this paper studied the spatiotemporal diversity of urban growth and the evolution of urban landscape pattern in Shenyang, and examined their driving forces. The results showed that in 1988-2004, the urban area in Shenyang increased persistently, and the growth intensity enhanced consistently, with the peaks occured in 2000-2004. The spatial differentiation of urban growth in the City was also distinct, with the southwest direction as the leading orientation, and the urban edges and different level economic development zones as the main growth areas. The urban landscape pattern became more and more complex, and the compactness index of urban development decreased. The evolution of urban landscape pattern was related to the characteristics of urban growth, which also showed spatiotemporal diversity. The urban growth and urban landscape pattern evolution in Shenyang were mainly attributed to the development of industrialization and the construction of different level economic development zones, the proper policies of local governments and the urban planning, as well as the development of traffic infrastructure.