Developing conservation strategies for Pinus koraiensis and Eleutherococcus senticosus by using model-based geographic distributions

We described potential changes in the geo- graphic distribution and occurrence probability of Pinus koraiensis Sieb. et Zucc. and Eleutherococcus senticosus （Rupr. et Maxim.） Maxim. in the counties of northeast China. This information was used to identify priority areas for protection and provide protection and management recommendations within each studied county. The two species were mapped in 2884 study plots throughout this region over a 4-year period （38°40＇N-53°30＇N, 115°05＇E- 135°02＇E）. We used the species distribution models （Maxent）, systematic conservation planning models （Marxan）, and Geographic Information Systems （ArcGIS 10.0）. The distributions of two species were correlated in the study area, enabling unique and economically viable joint conservation measures to be implemented. Three models were combined to identify feasible priority con- servation sites. We used local spatial statistics to assess all identified conservation areas in relation to potential climate change based shifts in the geographic distribution of the two species. Model-based conservation strategies were used to identify effective measures to protect and utilize these two tree species in the study region. This study pre- sents a novel technique for assessing wild plant distribu- tions, in addition to serving as a model for the conservation of other species within the framework of general forest management, ecological construction, and geographical surveying.

Forest plant and macrofungal differences in the Greater and Lesser Khingan Mountains in Northeast China:A regional-historical comparison and its implications

Forests in Northeast China in the Greater and Lesser Khingan Mountains(GKM and LKM)account for nearly 1/3 of the total state-owned forests in the country.Regional and historical comparisons of forest plants and macrofungi will favor biological conservation,forest management and economic development.A total of 1067 sampling plots were surveyed on forest composition and structure,with a macrofungi survey at Liangshui and Huzhong Nature Reserves in the center of two regions.Regional and historical differences of these parameters were analyzed with a redundancy ordination of their complex associations.There were 61-76 families,189-196 genera,and 369-384 species,which was only 1/3 of the historical records.The same dominant species were larch and birch with Korean pine(a climax species)less as expected from past surveys in the LKM.Shrub and herb species were different in the two regions,as expected from historical records.There was 10-50%lower species diversity(except for herb evenness),but 1.8-to 4-time higher macrofungi diversity in the GKM.Compared with the LKM,both tree heights and macrofungi density were higher.Nevertheless,current heights averaging 10 m are half of historical records(>20 m in the 1960s).Edible macrofungi were the highest proportion in both regions,about twice that of other fungal groups,hav-ing important roles in the local economy.A major factor explaining plant diversity variations in both regions was herb cover,followed by shrubs in the GKM and herb-dominant species in the LKM.Factors responsible for macrofungi variations were tree density and shrub height.Vaccinium vitis-idaea and Larix gmelinii in the GKM but tree size and diversity were important factors in the LKM.Our findings highlighted large spatial and historical differences between the GKM and LKM in plant-macrofungal composition,forest structure,and their complex associations,which will favor precise conservation and management of forest resources in two region in the future.

Variations in the natural 13C and 15N abundance of plants and soils under long-term N addition and precipitation reduction:interpretation of C and N dynamics

Background:The nitrogen isotope natural abundance(δ^(15)N)provides integrated information on ecosystem N dynamics,and carbon isotope natural abundance(δ^(13)C)has been used to infer how water-using processes of plants change in terrestrial ecosystems.However,howδ^(13)C andδ^(15)N abundances in plant life and soils respond to N addition and water availability change is still unclear.Thus,δ^(13)C andδ^(15)N abundances in plant life and soils were used to investigate the effects of long-time(10 years)N addition(+50 kg N·ha^(−1)·yr^(−1)and precipitation reduction(−30%of throughfall)in forest C and N cycling traits in a temperate forest in northern China.Results:We analyzed theδ^(13)C andδ^(15)N values of dominant plant foliage,litterfall,fungal sporophores,roots,and soils in the study.The results showed thatδ^(15)N values of foliage,litterfall,and surface soil layer’s(0–10 cm)total N were significantly increased by N addition,whileδ^(15)N values of fine roots and coarse roots were considerably decreased.Nitrogen addition also significantly increased theδ^(13)C value of fine roots and total N concentration of the surface soil layer compared with the control.The C concentration,δ^(13)C,andδ^(15)N values of foliage andδ^(15)N values of fine roots were significantly increased by precipitation reduction,while N concentration of foliage and litterfall significantly decreased.The combined effects of N addition and precipitation reduction significantly increased theδ^(13)C andδ^(15)N values of foliage as well as theδ^(15)N values of fine roots andδ^(13)C values of litterfall.Furthermore,foliarδ^(15)N values were significantly correlated with foliageδ^(13)C values,surface soilδ^(15)N values,surface soil C concentration,and N concentrations.Nitrogen concentrations andδ^(13)C values of foliage were significantly correlated withδ^(15)N values and N concentrations of fine roots.Conclusions:This indicates that plants increasingly take up the heavier 15N under N addition and the heavier 13C and 15N under precipitation reduction,suggesting that N addition and precipitation reduction may lead to more open forest ecosystem C and N cycling and affect plant nutrient acquisition strategies.

Long-time precipitation reduction and nitrogen deposition increase alter soil nitrogen dynamic by influencing soil bacterial communities and functional groups

The effects of precipitation reduction and nitrogen deposition increase on soil bacterial communities and functions impact soil nitrogen cycling. Seasonal changes could modify the effects of precipitation reduction and nitrogen deposition increase on bacterial communities and functions by changing soil environments and properties. Understanding soil microbial communities and the seasonal response of functions to precipitation reduction and nitrogen deposition increase may be important for the accurate prediction of changes in the soil nitrogen dynamics. Thus, a long-term field simulation experiment of nitrogen deposition increase and throughfall exclusion was established to investigate soil bacterial communities’ response to nitrogen deposition increase and/or precipitation reduction, with no nitrogen deposition increase and no precipation reduction as a control, in a temperate forest. We examined soil bacterial communities(Illumina sequencing) under different treatments during the winter, freezing-thawing cycle periods(FTCs), and growing season. The bacterial functional groups were predicted by the FAPROTAX database. The results showed that nitrogen deposition increase, precipitation reduction, the combined effect of nitrogen deposition increase and precipitation reduction, and seasonal changes significantly altered the soil bacterial community composition.Interestingly, by combining the result of a previous study in which nitrogen deposition increase increased the nitrous oxide flux in the same experimental system, the loss of soil nitrogen was increased by the decrease in denitrification and increase of nitrification bacteria under nitrogen deposition increase,while ammonification bacteria significantly increased and N-fixing bacteria significantly decreased with precipitation reduction compared to the control. In relation to seasonal changes, the aromatic-degrading, cellulolytic, and ureolytic bacteria were lowest during FTCs, which indicated that FTCs might inhibit biodegradation. Nitrification and nitrite-oxidizing bacteria increased with nitrogen deposition increase or precipitation reduction and in FTCs compared to the control or other seasons. The interaction between treatment and season significantly changed the soil bacterial communities and functions. These results highlight that nitrogen deposition increase, precipitation reduction, seasonal changes, and their interactions might directly alter bacterial communities and indirectly alter the dynamics of soil N.

Effects of long-term nitrogen addition on theδ^(15)N andδ^(13)C of Larix gmelinii and soil in a boreal forest

Background:Natural abundance of carbon(C)and nitrogen(N)stable isotope ratios(δ^(13)C andδ^(15)N)has been used to indicate the state and cycle of ecosystem C and N.However,it is still unclear how C and N cycle of boreal forests respond to the N deposition.Results:We conducted an 8-year continuous N addition field experiment in a Larix gmelinii forest in Greater Khingan Mountains,Northeast China.Four N treatments(0,25,50,75 kg N ha^(−1)year^(−1))were built.The effects of N addition on theδ^(13)C andδ^(15)N of needle,branch,bark,and fine root of Larix gmelinii and soil were studied.The result of the balance between the N input and output flux showed that N addition significantly increased theδ^(15)N in each organ of Larix gmelinii,but did not change theδ^(15)N of soil.We also found that the N absorption by needles of Larix gmelinii could increase the needle photosynthesis rate andδ^(13)C by increasing carboxylation,but N addition had no significant effect on theδ^(13)C of soil and other organs.In addition,both the soilδ^(15)N andδ^(13)C increased with the soil depth.Conclusions:Long-term N addition may lead to more open C and N cycles and further affect plant nutrient acquisition strategies in boreal forest ecosystems.

Symbiotic mycorrhizal types affect patterns of tree aboveground and belowground C allocation in Northeast China

Background Given the ubiquitous nature of mycorrhizal symbioses,different symbiotic fungi have obvious differences in structure and function,which may affect associated tree aboveground and belowground C allocation dynamics.However,the mechanisms underlying tree aboveground and belowground C allocation and its response to symbiotic mycorrhizal types and other factors(e.g.,resource availability)remain poorly understood.Results We used forest inventory data to explore the potential mechanism of tree aboveground and belowground C allocation patterns in Northeast China.Our results showed that tree-fungal symbioses were related to the patterns of tree C allocation.The ratio of aboveground to belowground C pool was significantly higher in ectomycorrhizal(EM)-associated trees than that in arbuscular mycorrhizal(AM)-associated trees.Symbiotic mycorrhizal types were associ-ated with the responses of tree aboveground and belowground C allocation to different factors,such as mean annual precipitation(MAP)and mean annual temperature(MAT).Almost all factors significantly increased aboveground C allocation in AM-associated trees but significantly decreased it in EM-associated trees.Moreover,after controlling the other factors,the effects of climate factors(MAT and MAP)on the C allocation of AM-and EM-associated trees were similar.Increases in MAT and MAP significantly increased belowground and aboveground C allocation,respectively.Conclusions Our results demonstrate symbiotic mycorrhizal types play an important role in controlling tree aboveground and belowground C allocation and dynamics.