Long-term effects of thinning on soil organic carbon fractions and carbon pool management indices in secondary forests of heavily burned areas.

Despite decades of recovery, soil carbon in heavily burned areas has failed to reach pre-fire levels. It is unclear whether stand management practices can promote soil organic carbon accumulation at such sites. This study evaluated the changes in soil labile organic carbon (LOC) fractions (including dissolved organic carbon (DOC), microbial biomass carbon (MBC), and easily oxidizable organic carbon (EOC)) and the carbon pool management index (CPMI) after the thinning of a heavily burned area in the Daxing'an Mountains and selected sample plots.

[Changes in diversity of marsh plant communities under shrub encroachment in Sanjiang Plain and their soil control factors].

In this study, we explored the changes in plant community diversity and their relationship with soil factors under shrub encroachment pressure by selecting four marsh areas in Sanjiang Plain with different degrees of shrub cover (, 0≤≤100%), including marsh with no shrub encroachment (=0), light shrub encroachment (0<≤30%), medium shrub encroachment (30%<≤70%), and heavy shrub encroachment (70%<≤100%). The results showed that shrub encroachment was the main reason for the heterogeneity of plant community composition in marsh. With shrub encroachment, the dominant species was replaced by , whereas disappeared.

Understory species composition mediates soil greenhouse gas fluxes by affecting bacterial community diversity in boreal forests.

Introduction: Plant species composition in forest ecosystems can alter soil greenhouse gas (GHG) budgets by affecting soil properties and microbial communities. However, little attention has been paid to the forest types characterized by understory vegetation, especially in boreal forests where understory species contribute significantly to carbon and nitrogen cycling.

Method: In the present study, soil GHG fluxes, soil properties and bacterial community, and soil environmental conditions were investigated among three types of larch forest [- forest (RL), - forest (LL), and -- forest (SLL)] in the typical boreal region of northeast China to explore whether the forest types characterized by different understory species can affect soil GHG fluxes.

Impacts of permafrost thaw on streamflow recession in a discontinuous permafrost watershed of northeastern China.

Permafrost thaw due to climate change is altering terrestrial hydrological processes by increasing ground hydraulic conductivity and surface and subsurface hydrologic connectivity across the pan-Arctic. Understanding how runoff responds to changes in hydrologic processes and conditions induced by permafrost thaw is critical for water resources management in high-latitude and high-altitude regions. In this study, we analyzed streamflow recession characteristics for 1964-2016 for the Tahe watershed located at the southern margin of the permafrost region in Eurasia.

Different variations in soil CO, CH, and NO fluxes and their responses to edaphic factors along a boreal secondary forest successional trajectory.

Forest succession is an important process regulating the carbon and nitrogen budgets in forest ecosystems. However, little is known about how and extent by which vegetation succession predictably affects soil CO, CH, and NO fluxes, especially in boreal forest. Here, a field study was conducted along a secondary forest succession trajectory from Betula platyphylla forest (early stage), then Betula platyphylla-Larix gmelinii forest (intermediate stage), to Larix gmelinii forest (late stage) to explore the effects of forest succession on soil greenhouse gas fluxes and related soil environmental factors in Northeast China.

Contribution of the nongrowing season to annual NO emissions from the permafrost wetland in Northeast China.

Permafrost regions store large amounts of soil organic carbon and nitrogen, which are major sources of greenhouse gas. With climate warming, permafrost is thawing and releasing an abundance of greenhouse gases into the atmosphere and contributing to climate warming. Numerous studies have shown the mechanism of nitrous oxide (NO) emissions from the permafrost region during the growing season.

Soil Microbial Community Response Differently to the Frequency and Strength of Freeze-Thaw Events in a Forest in the Daxing'an Mountains, China.

Sustained climate warming increases the frequency and strength of soil freeze-thaw (FT) events, which strongly affect the properties of soil microbial communities. To explore the responses and mechanisms of the frequency and strength of freeze-thaw events on soil microbial communities, a lab-scale FT test was conducted on forest soil in permafrost region from the Daxing'an Mountains, China. The number of FT cycles (FTN) had a greater effect on microbial communities than FT temperature fluctuation (FTF).

Building Virtual Watersheds: A Global Opportunity to Strengthen Resource Management and Conservation.

Modern land-use planning and conservation strategies at landscape to country scales worldwide require complete and accurate digital representations of river networks, encompassing all channels including the smallest headwaters. The digital river networks, integrated with widely available digital elevation models, also need to have analytical capabilities to support resource management and conservation, including attributing river segments with key stream and watershed data, characterizing topography to identify landforms, discretizing land uses at scales necessary to identify human-environment interactions, and connecting channels downstream and upstream, and to terrestrial environments. We investigate the completeness and analytical capabilities of national to regional scale digital river networks that are available in five countries: Canada, China, Russia, Spain, and United States using actual resource management and conservation projects involving 12 university, agency, and NGO organizations.

[Rainfall redistribution traits of three main forest types in Dagangshan Mountains of Jiangxi Province, China].

The redistribution processes of rainfall due to the canopy were studied on three typical forest types (Chinese fir forest, evergreen broad-leaved forest and Phyllostachys pubescens forest) in Dagangshan Mountains of Jiangxi Province. The results showed that from April to June, 2012, the total precipitation was 531.6 mm, with the maximum single rainfall of 61.

Multi-model ensemble simulation and projection in the climate change in the Mekong River Basin. Part I: temperature.

This paper evaluates the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) in simulating annual and decadal temperature in the Mekong River Basin from 1950 to 2005. By use of Bayesian multi-model averaging method, the future projection of temperature variation under different scenarios are also analyzed. The results show, the performances of climate model are more accurate in space than time, the model can catch the warming characteristics in the Mekong river Basin, but the accuracy of simulation is not good enough.

Food availability and animal space use both determine cache density of Eurasian red squirrels.

Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cache losses.

[Estimation of forest canopy closure by using partial least square regression].

Based on remote sensing and forest resources inventory data, this paper approached the feasibility of using Bootstrap approach to select optimal variables and using partial least square (PLS) regression to build a model for estimating forest canopy closure. The results showed that whether using a model built with all variables or a model with the optimal variables selected by Bootstrap approach, the relative deviation in estimating forest canopy closure was about 5%. The optimal variables selected in this paper differed greatly with those in the studies for other areas, suggesting that besides selection method, zonal vegetation and terrain could also induce the differences of selected optimal variables for the estimation of forest canopy closure.

[Distribution characteristics and seasonal dynamics of Cu and Zn in shrub-marsh plants in mountainous areas of northeast China].

The study on the distribution, accumulation, and seasonal dynamics of Cu and Zn in shrub-marsh plants Salix rosmarinifolia, Salix pentandra, Carex caespitosa and Carex schmidtii in mountainous areas of Northeast China showed that the Cu concentration in test plants varied from 6 to 12 mg x kg(-1), and its distribution was in the sequence of root > stem > leaf in S. rosmarinifolia and S. pentandra, and of stem > leaf > root in C.

[Effects of forest and swamp on hydrochemical characteristics of streams].

With the upper reaches of Gongbiela River in the northeast part of Xiaoxing' an Mountains as test area, this paper studied the hydrochemical characteristics of the streams in forest and swamp during the period of June - September 2004. The results indicated that the hydrochemistry of forest and swamp streams belonged to calcium-bicarbonate type I (C1(Ca)). The pH value, mineralization rate, total hardness, and HCO3(-), SO4(2-), Ca(2+), Mg(2+) and Fe concentrations of forest streams were lower than those of swamp streams, while the concentrations of total N, total P, Cl-, K+, and Na+ were in adverse.

[Quantitative estimation of vegetation coverage in Mu Us sandy land based on RS and GIS].

On the basis of oriented field investigation data and corresponding RS and GIS information, and by the method of ridge estimation, this paper studied the estimation model of vegetation coverage and its affecting factors in Yijinholo County of northeast Mu Us sandy land. The results showed that the vegetation coverage was affected by NDVI, and closely linked with such RS and GIS information as, TM7, TM2, TM 4/3 and gradient. Ridge estimation method could obviously improve the limitation of Least Square method, eliminate the adverse effects caused by existing complex estimation relation towards uncoiling undetermined parameter among the variables, and improve the estimate precision.

[Effects of forest harvesting on river runoff in Xiaoxing'anling].

By the method of runoff determination in large basin combined with contrast experiment in small watershed, and based on the runoff and forest resources data in past 35 years, this paper studied the serial changes of river runoff in Xiaoxing'anling after forest harvesting. The results showed that the river flow was increased in the early 10 years after forest harvesting, but decreased gradually with the growth and crown closure of artificial larch forest, tended towards or even lower than the level before harvesting. The river runoff had a close correlation with annual rainfall and the areas of forest harvesting and regeneration.

[Hydrochemical characteristics of three kinds of wetland in Gongbiela Basin].

The study on the hydrochemical characteristics of three representative kinds of wetland in Gongbiela Basin showed that in the water of test wetlands, HCO3 - was the dominant anion, accounting for 81.91% - 85.46% of total anions, and Ca2+ was the dominant cation, accounting for 56.

[Preliminary research on environmental characteristics of oasis-desert ecotone].

Taking Minqin Oasis in the downstream of Shiyanghe Rivers as example, the shrub characteristics of sand dune, which was closely related to the vegetation of the interface between the outside of oasis and desert, was studied in this paper. The change of vegetation coverage and dune density indicated that the vegetation coverage in the ecotone was obviously higher than that in the outside of oasis and in drift desert. There existed an area outside oasis that was obviously affected by human activies and 0-600 m away from the outside of oasis.