Ecosystem Research Station Research Articles

The underlying processes of a soil mite metacommunity on a small scale.

Metacommunity theory provides an understanding of how ecological processes regulate local community assemblies. However, few field studies have evaluated the underlying mechanisms of a metacommunity on a small scale through revealing the relative roles of spatial and environmental filtering in structuring local community composition. Based on a spatially explicit sampling design in 2012 and 2013, this study aims to evaluate the underlying processes of a soil mite metacommunity on a small spatial scale (50 m) in a temperate deciduous forest located at the Maoershan Ecosystem Research Station, Northeast China. Moran’s eigenvector maps (MEMs) were used to model independent spatial variables. The relative importance of spatial (including trend variables, i.e., geographical coordinates, and broad- and fine-scale spatial variables) and environmental factors in driving the soil mite metacommunity was determined by variation partitioning. Mantel and partial Mantel tests and a redundancy analysis (RDA) were also used to identify the relative contributions of spatial and environmental variables. The results of variation partitioning suggested that the relatively large and significant variance was a result of spatial variables (including broad- and fine-scale spatial variables and trend), indicating the importance of dispersal limitation and autocorrelation processes. The significant contribution of environmental variables was detected in 2012 based on a partial Mantel test, and soil moisture and soil organic matter were especially important for the soil mite metacommunity composition in both years. The study suggested that the soil mite metacommunity was primarily regulated by dispersal limitation due to broad-scale and neutral biotic processes at a fine-scale and that environmental filtering might be of subordinate importance. In conclusion, a combination of metacommunity perspectives between neutral and species sorting theories was suggested to be important in the observed structure of the soil mite metacommunity at the studied small scale.

Assessing the surface heating effect of the open-path analyzer of an eddy covariance system with fine-wire thermocouples

The open-path CO2/H2O analyzer that is currently widely used in the eddy covariance (EC) system possesses a surface heating effect, which may influence the accuracy of the eddy-flux measurements. Taking the open-path EC system in the temperate deciduous forest of the Maoershan Ecosystem Research Station as a case, we assessed the heating effect of the open-path CO2/H2O ana-lyzer (Li-7500) with fine-wire thermocouples and tested the applicability of Burba's equations. The results indicated that between April 23 and May 28 in 2016, the daytime air temperature in the mid-optical-path of the Li-7500 was on average 0.2 ℃ higher than the ambient air temperature, while the nocturnal temperature was almost equal, with the peak of the heating often occurring in the morning transition period and at noon or in the early afternoon. The diurnal variation in the heating effect on the sensible heat flux (HS,HE) estimated from the simple linear-fitting models in the fourth method by Burba (BurbaLF) was overall a rectangle-like wave, whereas that from the multiple regression models (BurbaMR) showed a weak mono-peak shape. Compared with direct mea-surements (K079) with the K-type fine-wire thermocouples (with a 0.079 mm diameter of single bare wire) and the HS,HE modeled with two fine-wire thermocouples (K079Model), the estimated HS,HE with the BurbaLF and BurbaMR varied little in the daytime with a lower but wider daytime-peak (20 W·m-2), a sharp transition between daytime and nighttime, and a typical nocturnal va-lue of ＜ 5 W·m-2. The peak values of HS,HE estimated from the K079 and K079Model could be higher than 40 W·m-2, and the values at night fluctuated around zero. The sensible heat flux in the optical-path of the Li-7500 was increased by 13.6% during the daytime. The value of the daytime heating effect on the CO2 turbulent flux (Fc,HC) estimated from the K079 and K079Model was averaged about 0.5 mg CO2·m-2·s-1, twice of the value estimated previously. Compared with the direct measurements, the Burba equations underestimated the Fc,HC around the noon due to the inadequate HS,HE, but overestimated the Fc,HC in the morning, the late afternoon and the night because of over-corrections of HS,HE, resulting in an overall overestimate of Fc,HC. These findings validated that both K079 and K079Model methods can be used to estimate the Fc,HC.

Wind characteristics of CzeCOS’s ecosystem station Bílý Kříž

Eddy-covariance is a direct and accurate method to measure exchanges of greenhouse gases and energy between ecosystems and the atmosphere under good turbulent mixing conditions. Calm conditions can affect the accuracy of the eddy-covariance measurements by potential gas buildup below the measurement height. This study characterizes wind patterns and calm periods at Bílý Kříž Ecosystem Research Station, using four-year (2010-2013) wind data measured on an eddy-covariance tower at the site, located in Beskids Mountains, Czech Republic. The site is covered by young, dense Norway spruce forest on a 12.5° slope facing South. The results show that the prevailing wind direction was from S to SW direction (55 % frequency of occurrence), and to a much lesser extent from N, NE and NW but including the strongest winds above 12 m s-1, possibly during gale or storm events. Calm condition (u < 1 m s-1) accounted for 34 % of year time. Summer and Spring were the calmest seasons. Occurrence frequencies of calm conditions for the six-month periods from May to October (plant growing season) were higher than those for the remaining parts of the year (on average 39 % vs 28 % respectively). One should be aware of the calm periods in May-October when processing eddy-covariance data, since it is the time period of most contribution of forest ecosystem as a sink of CO2.

Effects of predation risk on behavior, hormone levels, and reproductive success of plateau pikas

AbstractPredation is a strong selective force that affects animal population dynamics either through direct killing or predation risk effects. Although recent empirical research has shown that the non‐consumptive effect of predator risk on prey dynamics can be as large (or even larger) as direct effects, little is known about the strength of predation risk effects in wild populations or the physiological mechanisms that mediate them. Here, we test both the predator‐sensitive food hypothesis and predation‐stress hypothesis in a single system by investigating activity budgets, stress/sex hormone levels, and demography of plateau pikas (Ochotona curzoniae) and their predators in Haibei Alpine Meadow Ecosystem Research Station of the Chinese Academy of Science. During the study period (2009 and 2010), plateau pikas experienced various predation pressures due to many predators being poisoned in 2010. In the year of high predator numbers, pikas spent more time on vigilant duty and less time foraging and they also showed higher plasma corticosterone levels and lower plasma estradiol and testosterone levels. Reproductive success and male with developed testes also reduced in the year of higher predation risk. In general, our results support both the predator‐sensitive food and predation‐stress hypothesis. Predator‐induced risk affects prey reproduction by changes in feeding patterns and stress physiology.

Changes in stoichiometry of soil carbon, nitrogen and phosphorus in the early stage of temperate forest succession in Maoershan, Northeast China

A soil displacement experiment was established in the Maoershan Forest Ecosystem Research Station in 2004, replacing the cropland soil of the 0-30 cm depth with the eluvial horizon soil (A treatment), the sediment horizon soil (B treatment) and the parent material horizon soil (weathered sand, C treatment) of an adjacent temperate broadleaved stand. The three treatments simulated the secondary successions from forest clear-cutting, bare soil without seed bank, and primary succession, respectively. Changes in soil carbon, nitrogen, phosphorus and their stoichiometry were examined in 2014. The results indicated that during the ten-year succession, the contents of soil C, N and P changed insignificantly in the A treatment. The contents of soil C and N decreased by 34.7% and 38.6% in the B treatment, but increased by 63.4% and 198.4% in the C treatment, respectively. The slope of the log-transformed N-C relationships decreased significantly during the succession, while the slope of the log-transformed P-N relationships increased significantly. After 10-year's succession, only the C:N decreased by 44.5%, and the N:P increased by 283.6% in the C treatment, with no significant changes for others. The contents of C, N and P were significantly correlated with the root biomass and necromass, suggesting that the succession might change the soil elements and their stoichiometric relationships through modifying organic matter inputs.

Variation Characteristics and Sources Analysis of Atmospheric Volatile Organic Compounds in Changbai Mountain Station

Volatile organic compounds (VOCs) play very important roles in the formation of ozone and secondary organic aerosols. The concentrations, compositions, and seasonal variation of VOCs were measured in 2012 at Changbai Mountain Forest Ecosystem Research Station, a remote station in Northeast China. Weekly samples were collected in the Changbai Mountain area and analyzed via gas chromatography-mass spectrometry. The results showed that the annual mean concentration of total VOCs (TVOCs) was 10.7×10-9±6.2×10-9. Halohydrocarbon was the most abundant component, accounting for 37% of the total VOCs, followed by alkanes and aromatics, accounting for 33% and 15% respectively, and alkenes accounted for 15%. The seasonal variation of TVOCs in this area was obvious, and the order was spring >autumn >summer >winter. TVOCs concentration in spring was very significantly higher than those in any other season (P<0.05). The principal component analysis (PCA) was used to identify the sources of the VOCs. Five sources were resolved by the PCA, including traffic sources, LPG,biogenic sources, combustion sources, industrial sources and regional transportation. The HYSPLIT-4.0 model was used to analyze the effect of pollutant transport, and the results indicated that the transport of pollutants from southwest had a significant effect on the increase of VOCs concentration.

Maize biomass simulation based on dynamic photosynthate allocation.

Photosynthate allocation is critical to crop growth and biomass formation, and it is also a key part of crop simulation. A photosynthate allocation model of maize was established based on photosynthate allocation mechanisms as well as the photosynthate allocation characteristics of maize at different stages. This model was then coupled with the CO2 assimilation module of WOFOST crop model to simulate the biomass dynamics of different organs of maize on daily scale. It was validated by 5 years' field experiment data of spring maize from Jinzhou Agricultural Ecosystem Research Station. The results showed that, the model could explain about 95.4% of maize's total biomass change, while 87.0%, 85.3%, 67.9%, 76.5% and 87.5% of vegetative, leaf, root, stem, and ear biomass variations, respectively. This model could fulfill accurate simulation of different organ biomass dynamics of maize.

Responses and influencing factors of foliar photosynthetic characteristics of &amp;lt;italic&amp;gt;Larix gmelinii &amp;lt;/italic&amp;gt;to changing environments

Investigating tree photosynthetic capacity is important for understanding the carbon cycles of terrestrial ecosystems and their responses and adaptation to climatic change. Dahurian Larch ( Larix gmelinii ) is one of the dominant tree species in Chinese boreal forests with a broad bio-geographic range under divergent habitats, and thus an ideal tree species for exploring tree adaptation to environment. In this study, we measured the foliar photosynthesis and associated physiological parameters of 30-year-old Dahurian larch trees from six provenances in a common garden at the Maoershan Forest Ecosystem Research Station in Northeast China for three years (2009–2011). The six provenances were located across the natural distribution range of the larch, spanning approximately 4° in latitude (48°–52°N), 5°C in mean annual temperature ( - 2.3–2.6°C), and 200 mm in mean annual precipitation (425–622 mm). To access the top canopy of the sampled trees, we constructed 15-m-high wooden scaffolds at the site. Three representative trees from each provenance were selected for the measurements per month from mid May to mid September. We measured three fully expanded sunlit fascicles on young short shoots at the top of the canopy of each tree in situ with an infrared gas analyzer. On non-rainy days, light and CO2 response curves were measured between 06:30 and 12:00 hours under optimal conditions. Our goal was to explore impacts of environmental changes on foliar photosynthetic characteristics of the larch and their driving factors. The main results were summarized as follows: (ⅰ) The leaf-area-based maximum net photosynthetic rate ( P max-a), dark respiratory rate ( R a), apparent quantum yield (AQY), maximum rate of carboxylation ( V max), maximum electron transport rate ( J max) and triose phosphate utilization rate (TPU) all increased significantly ( P T s) and aridity index (AI) of the seed-source original sites, while the light compensation point (LCP) and photorespiratory rate ( R p) showed an opposite trend. This suggests that the leaf photosynthetic characteristics genetically adapt to the original site conditions of the tree seed-sources, among which the temperature and precipitation are the major driving factors. (ⅱ) P max-a was positively correlated with AQY, V max, J max, TPU, and leaf nitrogen concentration, but negatively with LCP and R p ( P T s habitats had higher sensitivity of P max-a associated with other characteristics. (ⅲ) P max-a was significantly and positively correlated with 3-day mean temperature, mean monthly temperature, mean growing season temperature, 3-day mean relative humidity, and mean monthly precipitation of the common garden, while the R a showed opposite trends with the environmental factors except for the mean growing season temperature. This indicates that the leaf photosynthetic characteristics acclimate to the environmental conditions of the common garden. However, the trees from higher T s habitats had lower intercepts of the regression equations of P max-a associated with the environmental factors, and had the opposite trends for R a except for the mean growing season temperature. The results suggest that the relationships between foliar photosynthetic characteristics and environment are jointly controlled by both phenotypic acclimation to current site conditions and genotypic adaptation to the original environment of the seed-source. These findings provide insights on understanding the survival, reproduction and distribution of Dahurian larch to changing environments.

Soil microbial characteristics and the influencing factors in subtropical forests

Soil microorganisms play an important role in the soil formation, nutrient cycling, and regulating plant productivity. Bacteria, fungi and actinomycetes are main microbial groups being responsible for the soil ecosystems. However, responses of soil microbial communities to litter characteristics and soil properties at the regional scale are poorly understood. Litter characteristics, soil properties and soil microbial communities were measured in coniferous forests and broadleaved forests at three natural forests (Dinghu Mountain National Field Forest Ecosystem Research Station (DHS), Ailao Mountain National Field Forest Ecosystem Research Station (ALS), Daming Mountain Nature Reserve Station (DMS)) and a plantation (Heshan National Field Forest Ecosystem Research Station (HSZ)) ecosystems in order to explore the effects of litter characteristics on soil microbial community structure. In our study, the soil microbial communities were analyzed by dilution-plate method. Furthermore, we analyzed the determined factors of soil microbial community structure in the forest ecosystems. The results showed that season, forest type and sampling site influenced the soil microorganisms and community structure. There were the obvious seasonal dynamics of soil microorganisms in subtropical region, China. The soil microbial counts and the ratio of fungi and bacteria in wet season were higher than those in dry season. The counts of bacteria and total microorganisms in coniferous forests were less than those in broadleaved forests. Moreover, the ratios of fungi and bacteria were greater in coniferous forests than that in broadleaved forests. Similarly, the counts of bacteria and total microorganisms in plantations were less than those in natural forests. Besides, the fungi in the two forests showed the different trends in dry season and wet season. Soil fungi in natural forests were higher than that in plantation in dry season, but it showed the opposite pattern in the wet season. The ratio of fungi and bacteria was significantly higher in plantation than that in natural forests. Linear regression results showed that variations of fungi, actinomycetes and total microorganisms were primarily explained by the litter quality in coniferous forests, but the variations of fungi and actinomycetes were explained by the litter storages in broadleaved forests. Redundancy analysis (RDA) results showed that soil and litter properties explained 79.7% of total variation in microbial community structure. Furthermore, the variations of microbial community structure were explained 19.1%, 16.7%, 16.6% and 11.6% by soil total nitrogen (STN), soil organic carbon (SOC), soil water content (SWC) and the ratio of soil organic carbon and the nitrogen (soil C:N), respectively. Overall, our findings will facilitate a better understanding of soil microbial characteristics in subtropical forests.

Characteristics, source apportionment and reactivity of ambient volatile organic compounds at Dinghu Mountain in Guangdong Province, China

Volatile organic compounds (VOCs) play a very important role in the formation of ozone and secondary organic aerosols. The concentrations, compositions, and variability of VOCs were measured from 2005 to 2008 at Dinghu Mountain Forest Ecosystem Research Station, a remote station in Southeast China. Weekly samples were collected in the Dinghu Mountain area and were analysed via gas chromatography–mass spectrometry. The results revealed that the total VOC concentrations decreased continuously and that the dominant VOC components were alkanes (43%) and aromatics (33%), followed by halo-hydrocarbons (12%) and alkenes (12%). The general trend of seasonal variation indicated higher concentrations in spring and lower concentrations in summer. The positive matrix factorization model was used to identify the sources of the VOCs. Seven sources were resolved by the PMF model: (1) vehicular emissions, which contributed 25% of the total VOC concentration; (2) industrial sources and regional transportation, contributing 17%; (3) paint solvent use, contributing 17%; (4) fuel evaporation, contributing 13%; (5) stationary combustion sources, contributing 12%; (6) biogenic emissions, contributing 10%; and aged VOCs, contributing only 6%. The HYSPLIT model was used to analyse the effect of pollutant transport, and the results indicated that the transport of pollutants from cities cannot be ignored. Finally, the OH radical loss rates and ozone formation potentials (OFPs) were calculated, and the results indicated isoprene to have the highest OH radical loss rate and toluene to be the largest contributor to the OFP at the Dinghu Mountain site.

人工红松林步行虫(Coleoptera: Carabidae)群落物种共存格局动态分析

PDF HTML阅读 XML下载 导出引用 引用提醒 人工红松林步行虫(Coleoptera:Carabidae)群落物种共存格局动态分析 DOI: 10.5846/stxb201504050680 作者: 作者单位: 哈尔滨师范大学,哈尔滨师范大学,哈尔滨师范大学,哈尔滨师范大学,哈尔滨师范大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41471037，41101049，41371072，41430857）；黑龙江省普通本科高等学校青年创新人才培养计划（UNPYSCT-2015054）；哈尔滨师范大学青年学术骨干资助计划项目（KGB201204）；哈尔滨师范大学硕士研究生创新科研项目（HSDSSCX2015-10） Co-occurrence pattern dynamics of a Carabidae community in a Pinus koraiensis planted forest Author: Affiliation: Harbin Normal University,Harbin Normal University,Harbin Normal University,Harbin Normal University,Harbin Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:揭示群落物种共存格局是群落生态学研究的重点内容之一，零模型的应用极大的促进了群落物种共存格局及其调控机制的进展，然而针对地下生物群落共存格局动态特征的研究并不多见。在帽儿山森林生态站的人工红松林内，通过5次调查取样基于零模型模拟分析小尺度空间（20 m×20 m）步行虫群落物种共存格局的动态特征。结果表明：（1）共捕获步行虫20种，2278只个体，其中Carabus billergi maoershanensis为所有调查季节数量最具优势且分布最广泛的物种，步行虫群落结构具明显的时间变异性；（2）2013年6月步行虫群落为集群性共存格局，而2014年8、10月为竞争性共存格局，基于目前的零模型指标和法则难以准确揭示其他月份是集群性还是竞争性的共存格局，但所有季节的群落均表现为明显的非随机性共存格局，这些共存格局的发现并不完全支持Diamond的群落构建机制理论；（3）所有调查季节均发现很少的显著物种对，基于更严格的检验表明群落中集群性物种对多于隔离性物种对，那些表现为显著的非随机性共存关系的物种对往往是群落内数量较大且分布广泛的优势和常见物种。表明非随机性共存格局可能是帽儿山人工红松林小尺度空间步行虫群落的常见格局，这种非随机性格局具一定的短期动态稳定性，但不同季节这种非随机性共存格局类型表现不同，群落内这些较少的显著物种对可能对群落物种共存格局具有一定的贡献。 Abstract:One of the most important tasks in community ecology is identifying the co-occurrence patterns of the community and identifying the underlying processes that control such patterns. Null model analysis,which has been facilitated by the processes of biodiversity maintenance, has been used to identify the co-occurrence patterns in communities. However, few studies have focused on co-occurrence pattern dynamics of belowground soil communities. In this study, we identify the co-occurrence pattern dynamics of a Carabidae community in a Pinus koraiensis planted forest on a small scale, based on five investigations from June 2013 to October 2014. A plot (20 m×20 m) was established and further divided into 100 squares of 2 m×2 m at the Maoer Mountain Ecosystem Research Station of the Northeast Forestry University in Heilongjiang Province, Northeast China. One hundred pitfall traps were set to collect the Carabidae community for each investigation. To determine non-random patterns of species co-existence and significant species pairs in Carabidae communities, the null model was used to generate expected patterns in the absence of species interactions. In total, 20 species and 2278 individuals were captured. Carabus billergi maoershanensis was the most abundant and most widely distributed species among all communities. Carabidae community composition exhibited significant temporal variability among individuals during the experimental period. With the model algorithm of fixed row and column sums, results of the C-score and V-ratio showed that co-occurrence of species in June 2013 was aggregated, a finding that was inconsistent with Diamond's assembly rules. Moreover, with the model algorithm of fixed row sums and probability column sums and considering both algorithms, results of the C-score and V-ratio indicated that co-occurrence patterns of Carabidae communities in August and October 2014 were segregated, which was consistent with Diamond's assembly rules. Although the results of the C-score and V-ratio suggest that the co-occurrence patterns of the Carabidae communities in July and September 2013 were aggregated or segregated based on analysis of the null model, it can be inferred that non-random co-occurrence patterns were detected in all Carabidae communities. Furthermore,based on our observations of the co-occurrence patterns in the Carabidae communities, the Diamond's assembly rules were partly rejected. Few significant species pairs were detected among all Carabidae communities. A greater number of aggregated species pairs were observed in comparison to segregated species pairs among all communities. The species comprising those significant species pairs were dominant or common species, and were comparatively more widely distributed throughout the plot in each season. In addition, the Pianka (Oik) indices between those dominant and common species were relatively greater than that observed between other species pairs. The results suggest that those significant species pairs might also make important contributions to community composition. The present study demonstrated that a non-random co-occurrence pattern might be common in a small-scale Carabidae community in a Pinus koraiensis planted forest. This non-random co-occurrence pattern also showed short-term stability during the study period;however, the properties of the sepatterns vary among the different seasons. The significant species pairs possibly contribute directly to observed community co-occurrence patterns, and more focus should be placed on the contributions of those dominant and common Carabidae species in the future. 参考文献 相似文献 引证文献

Crop evapotranspiration-based irrigation management during the growing season in the arid region of northwestern China

In arid northwestern China, water shortages have triggered recent regulations affecting irrigation water use in desert-oasis agricultural systems. In order to determine the actual water demand of various crops and to develop standards for the rational use of water resources, we analyzed meteorological data from the Fukang desert ecosystem observation and experiment station (FKD), the Cele desert-grassland ecosystem observation and research station (CLD), and the Linze Inland River Basin Comprehensive Research Station (LZD), which all belong to the Chinese Ecosystem Research Network. We researched crop evapotranspiration (ETc) using the water balance method, the FAO-56 Penman-Monteith method, the Priestley-Taylor method, and the Hargreaves method, during the growing seasons of 2005 through 2009. Results indicate substantial differences in ETc, depending on the method used. At the CLD, the ETc from the soil water balance, FAO-56 Penman-Monteith, Priestley-Taylor, and Hargreaves methods were 1150.3±380.8, 783.7±33.6, 1018.3±22.1, and 611.2±23.3 mm, respectively; at the FKD, the corresponding results were 861.0±67.0, 834.2±83.9, 1453.5±47.1, and 1061.0±38.2 mm, respectively; and at the LZD, 823.4±110.4, 726.0±0.4, 722.3±29.4, and 1208.6±79.1 mm, respectively. The FAO-56 Penman-Monteith method provided a fairly good estimation of E Tc compared with the Priestley-Taylor and Hargreaves methods.

Changes in photosynthesis of alpine plant Saussurea superba during leaf expansion

The native alpine plant Saussurea superba is widely distributed in Qinghai–Tibetan Plateau regions. The leaves of S. superba grow in whorled rosettes, and are horizontally oriented to maximize sunlight exposure. Experiments were conducted in an alpine Kobresia humilis meadow near Haibei Alpine Meadow Ecosystem Research Station (37°29′–37°45′N, 101°12′–101°33′E; alt. 3200 m). Leaf growth, photosynthetic pigments and chlorophyll fluorescence parameters were measured in expanding leaves of S. superba. The results indicate that leaf area increased progressively from inner younger leaves to outside fully expanded ones, and then slightly decreased in nearly senescent leaves, due to early unfavorable environmental conditions, deviating from the ordinary growth pattern. The specific leaf area decreased before leaves were fully expanded, and the leaf thickness was largest in mature leaves. There were no significant changes in the content of chlorophylls (Chl) and carotenoids (Car), but the ratios of Chl a/b and Car/Chl declined after full expansion of the leaves. The variation of Chl a/b coincided well with changes in photochemical quenching (qP) and the fraction of open PSII reaction centers (qL). The maximum quantum efficiency of PSII photochemistry after 5 min dark relaxation (F(v)/F(m)) continuously increased from younger leaves to fully mature leaves, suggesting that mature leaves could recover more quickly from photoinhibition than younger leaves. The light-harvesting capacity was relatively steady during leaf expansion, as indicated by the maximum quantum efficiency of open PSII centers (\(F_{\text{v}}^{{\prime }}\)/\(F_{\text{m}}^{{\prime }}\)). UV-absorbing compounds could effectively screen harmful solar radiation, and are a main protection way on the photosynthetic apparatus. The decline of qP and qL during maturation, together with limitation of quantum efficiency of PSII reaction centers (L(PFD)), shows a decrease of oxidation state of QA in PSII reaction centers under natural sunlight. Furthermore, light-induced (ΦNPQ) and non-light-induced quenching (ΦNO) were consistent with variation of L(PFD). It is concluded that the leaves of S. superba could be classified into four functional groups: young, fully expanded, mature, and senescent. Quick recovery from photoinhibition was correlated with protection by screening pigments, and high level of light energy trapping was correlated with preservation of photosynthetic pigments. Increasing of ΦNPQ and ΦNO during leaves maturation indicates that both thermal dissipation of excessive excitation energy in safety and potential threat to photosynthetic apparatus were strengthened due to the declination of qP and qL, and enhancement of L(PFD).

Canopy interception loss in a Pinus sylvestris var. mongolica forest of Northeast China

Pinus sylvestris var. mongolica is one of the main species to be afforested in deserts of China. But little work has been carried out on the canopy interception loss of this plant species. For researching the canopy interception loss of a natural P. sylvestris forest, we observed the gross precipitation, gross snowfall, throughfall and stemflow in a sample plot at the Forest Ecosystem Research Station of Mohe in the Great Khingan Mountains of Northeast China from July 2012 to September 2013. Considering the spatial variability of the throughfall, we increased the area rather than the number of collector and randomly relocated them once a week. The results demonstrated that the throughfall, stemflow, and derived estimates of rainfall and snowfall interception loss during the main rainy and snowy seasons were 77.12%±5.70%, 0.80%, 22.08%±5.51% and 21.39%±1.21% of the incident rainfall or snowfall, respectively. The stemflow didn’t occur unless the accumulated rainfall reached up to 4.8 mm. And when the gross precipitation became rich enough, the stemflow increased with increasing tree diameters. Our analysis revealed that throughfall was not observed when rainfall was no more than 0.99 mm, indicating that the canopy storage capacity at saturation was 0.99 mm for P. sylvestris forest.

Impact of precipitation patterns on biomass and species richness of annuals in a dry steppe.

Annuals are an important component part of plant communities in arid and semiarid grassland ecosystems. Although it is well known that precipitation has a significant impact on productivity and species richness of community or perennials, nevertheless, due to lack of measurements, especially long-term experiment data, there is little information on how quantity and patterns of precipitation affect similar attributes of annuals. This study addresses this knowledge gap by analyzing how quantity and temporal patterns of precipitation affect aboveground biomass, interannual variation aboveground biomass, relative aboveground biomass, and species richness of annuals using a 29-year dataset from a dry steppe site at the Inner Mongolia Grassland Ecosystem Research Station. Results showed that aboveground biomass and relative aboveground biomass of annuals increased with increasing precipitation. The coefficient of variation in aboveground biomass of annuals decreased significantly with increasing annual and growing-season precipitation. Species richness of annuals increased significantly with increasing annual precipitation and growing-season precipitation. Overall, this study highlights the importance of precipitation for aboveground biomass and species richness of annuals.

择伐对思茅松自然种群结构和空间分布格局的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 择伐对思茅松自然种群结构和空间分布格局的影响 DOI: 10.5846/stxb201406051159 作者: 作者单位: 中国林业科学研究院资源昆虫研究所,国家林业局普洱森林生态系统定位研究站;中国林业科学研究院资源昆虫研究所,国家林业局普洱森林生态系统定位研究站;中国林业科学研究院资源昆虫研究所,中国科学院植物研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 云南省科技计划项目(2013RA004);中国林科院中央级公益性科研院所基本科研业务费专项资金资助项目(riricaf2012001Z);林业公益性行业科研专项项目(201404211) Influences of selective cutting on the structure and spatial distribution patterns of a natural population of Pinus kesiya var. langbianensis Author: Affiliation: Research Institute of Resource Insects,The Pu’er Forest Eco-system Research Station,State Forestry Administration;Research Institute of Resource Insects,The Pu’er Forest Eco-system Research Station,State Forestry Administration,The Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:思茅松是云南省重要的材脂兼用树种,而择伐是思茅松天然林管理的有效手段,也是获取木材的重要途径。基于对云南省景谷县思茅松天然林的样地调查数据,采用种群径级结构代替年龄结构、Ripley的L函数点格局等方法,对思茅松天然林在不同强度择伐10a后的种群结构和空间分布格局及其不同发育阶段在不同尺度下的相互关系进行了系统研究和分析。结果表明:择伐10a后3种类型的思茅松自然种群的胸径、树高之间呈显著的正相关且可用幂指数模拟预测模型。未择伐的思茅松种群呈衰退型,轻度择伐(12.9%)后种群呈稳定型,中度择伐(29.3%)后的种群属增长型,适当的中度择伐有利于自然种群的更新;未择伐与中度择伐后的思茅松种群分布格局整体呈随机型,但后者较前者更趋向于均匀分布,轻度择伐后的思茅松种群分布格局随着尺度的增加由随机转向聚集分布。择伐对不同径级思茅松天然林种群空间分布格局有重要影响,未择伐的思茅松自然种群随着发育阶段的发展,多数尺度上由随机分布逐渐转变为聚集分布,至大树则又以随机分布为主;轻度择伐和中度择伐的思茅松自然种群则随着发育阶段的发展而由完全的随机分布逐渐转变为聚集分布,中度择伐的聚集分布则更为明显。思茅松不同发育阶段间在所有尺度上基本都呈显著正相关,表明思茅松种群种内竞争弱,有利于种群的维持。 Abstract:Pinus kesiya var. langbianensis is an important source of timber and resin production in Yunnan Province, China. In forest management, selective cutting is an effective means of P. kesiya forest management, and is also the primary way to obtain timber. This study is based on data from sampling plots of a P. kesiya natural forest in Jinggu County, Yunnan Province. The method of substituting space for time using the L function (based on the derivatives of Ripley's K function) was used to analyze the influence of 10 years of different selective cutting intensities on the structure and spatial distribution patterns of a P. kesiya natural forest population. This study also investigated the relationship between P. kesiya's development stages and spatial scales. The results showed a significantly positive correlation between DBH and tree height after 10 years of selective cutting, and are used as a power model to simulate a prediction model. The P. kesiya population without selective cutting showed a decling population type. The population under low intensity selective cutting (12.9%) showed a stable type, and the diameter-class structure of the population under medium intensity selective cutting (29.3%) presented an invert "J" shape, was an expanded type, and had more individuals with the small diameter class. This indicates that medium intensity selective cutting is useful for promoting regeneration. Both P. kesiya populations without selective cutting and with selective cutting under medium intensity were randomly distributed, but the latter tended to be more regularly distributed than the former. The spatial pattern of low intensity cutting changed from random to aggregated with the increase of scale. Selective cutting intensities changed the spatial distribution patterns of different DBH classes, and also influenced the overall distribution patterns of P. kesiya. With the progression of developmental stages, the distribution of trees under no selective cutting changed from random to aggregate. For large trees, the distribution pattern was most often random; the distribution patterns under low and medium intensity cutting changed from completely random to aggregated with the development, and an aggregated distribution at medium intensity selective cutting is more apparent than low intensity selective cutting. The different growth stages of P. kesiya populations were significantly positively correlated at all scales. Intraspecific competition was weak, which had the advantage of population maintenance. Low and medium intensity selective cutting may enhance the stability of the forest community spatial structure. Medium selective cutting is more effective at forest structure maintenance than low selective cutting. Our results have important theoretical and practical implications for establishing a development plan for the sustainable management of P. kesiya forests. 参考文献 相似文献 引证文献

Relative roles of spatial factors, environmental filtering and biotic interactions in fine-scale structuring of a soil mite community

Community theories suggest that community structuring depends on dispersal limitation, environmental filtering and biotic interactions. However, the relative roles of these factors at fine scale are less well understood. In this study, we attempt to determine the relative roles of spatial factors, environmental filtering and biotic interactions in the fine-scale (5 m) structuring of a soil mite community from a temperate deciduous forest in the Maoershan Ecosystem Research Station in northeastern China. In August 2012, we established three plots and collected 100 samples from each plot in a 5 × 5 m2 area using a spatially delimited sampling design. To quantify the relative contributions of the spatial and environmental processes, Moran's eigenvector maps (MEMs), variation partitioning analysis and partial Mantel test were used. Null and neutral models were used to disentangle the effects of biotic interactions. Null mode analyses were conducted for non-random patterns of species co-existence and significant species-pairs in the assemblage of soil mites, and to determine whether the observed pattern was the result of biotic interactions. The neutral model was used to identify whether the community structure shows divergence, convergence or neutrality. The results indicated that the relatively large and significant variance was due to spatial factors in all plots. The contribution of environmental filtering was relatively low and non-significant in all plots based on variation partitioning, while it was significant in Plot II based on a partial Mantel test. Soil organic matter content, soil pH, and soil and litter water content explained a significant part of the variance observed in the distribution of the mite community. Furthermore, the null model revealed a non-random co-occurrence pattern in the soil mite community, and the environmental niche overlap indicated a weak contribution of biotic interactions. The observed mean dissimilarity implied significant divergence in communities based on neutral model analysis. Collectively, these results emphasize that both spatial and environmental processes were important drivers in the fine-scale structuring of soil mite communities in a temperate deciduous forest and that biotic interactions were less influential in the observed pattern.

Fluxes of methane, carbon dioxide and nitrous oxide in an alpine wetland and an alpine grassland of the Tianshan Mountains, China

Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) are known to be major greenhouse gases that contribute to global warming. To identify the flux dynamics of these greenhouse gases is, therefore, of great significance. In this paper, we conducted a comparative study on an alpine grassland and alpine wetland at the Bayinbuluk Grassland Eco-system Research Station, Chinese Academy of Sciences. By using opaque, static, manual stainless steel chambers and gas chromatography, we measured the fluxes of CH4, N2O and CO2 from the grassland and wetland through an in situ monitoring study from May 2010 to October 2012. The mean flux rates of CH4, N2O and CO2 for the experimental alpine wetland in the growing season (from May to October) were estimated at 322.4 μg/(m2·h), 16.7 μg/(m2·h) and 76.7 mg/(m2·h), respectively; and the values for the alpine grassland were −88.2 μg/(m2·h), 12.7 μg/(m2·h), 57.3 mg/(m2·h), respectively. The gas fluxes showed large seasonal and annual variations, suggesting weak fluxes in the non-growing season. The relationships between these gas fluxes and environmental factors were analyzed for the two alpine ecosystems. The results showed that air temperature, precipitation, soil temperature and soil moisture can greatly influence the fluxes of CH4, N2O and CO2, but the alpine grassland and alpine wetland showed different feedback mechanisms under the same climate and environmental conditions.

Nitrogen deposition impacts on the amount and stability of soil organic matter in an alpine meadow ecosystem depend on the form and rate of applied nitrogen

SummaryThe effects of atmospheric nitrogen (N) deposition on carbon (C) sequestration in terrestrial ecosystems are controversial. Therefore, it is important to evaluate accurately the effects of applied N levels and forms on the amount and stability of soil organic carbon (SOC) in terrestrial ecosystems. In this study, a multi‐form, small‐input N addition experiment was conducted at the Haibei Alpine Meadow Ecosystem Research Station from 2007 to 2011. Three N fertilizers, NH4Cl, (NH4)2SO4 and KNO3, were applied at four rates: 0, 10, 20 and 40 kg N ha−1 year−1. One hundred and eight soil samples were collected at 10‐cm intervals to a depth of 30 cm in 2011. Contents and δ13C values of bulk SOC were measured, as well as three particle‐size fractions: macroparticulate organic C (MacroPOC, &gt; 250 µm), microparticulate organic C (MicroPOC, 53–250 µm) and mineral‐associated organic C (MAOC, &lt; 53 µm). The results show that 5 years of N addition changed SOC contents, δ13C values of the bulk soils and various particle‐size fractions in the surface 10‐cm layer, and that they were dependent on the amounts and forms of N application. Ammonium‐N addition had more significant effects on SOC content than nitrate‐N addition. For the entire soil profile, small additions of N increased SOC stock by 4.5% (0.43 kg C m−2), while medium and large inputs of N decreased SOC stock by 5.4% (0.52 kg C m−2) and 8.8% (0.85 kg C m−2), respectively. The critical load of N deposition appears to be about 20 kg N ha−1 year−1. The newly formed C in the small‐input N treatment remained mostly in the &gt; 250 µm soil MacroPOC, and the C lost in the medium or large N treatments was from the &gt; 53 µm POC fraction. Five years of ammonium‐N addition increased significantly the surface soil POC:MAOC ratio and increased the instability of soil organic matter (SOM). These results suggest that exogenous N input within the critical load level will benefit C sequestration in the alpine meadow soils on the Qinghai–Tibetan Plateau over the short term.

Influence of thinning on acidic deposition in Chinese fir plantations

Acidic deposition, which is mainly caused by atmospheric pollution, is one of the global environmental problems. Thinning is an effective management to improve the tree productivity, reduce the wildfire risk and maintain a healthy forest. Since thinning may reduce the effect of acidic deposition, the effect of thinning on acidic deposition was estimated. The biomass, soil properties, pH value of runoff and groundwater in both unthinned and thinned Chinese fir plantations were measured and compared over a 5-year period (2–6 years after thinning). The results indicated that acidic deposition in the Huitong State Ecosystem Research Station was serious, and it got worse with time. Forest thinning resulted in a huge change in biomass and soil properties. During the 5-year monitoring period, biomasses of understory and litter, plant species richness, coverage of undergrowth plant layer were significantly higher in thinned site than in unthinned site. Moreover, higher soil fertility as well as lower amounts of runoff and groundwater were found in thinned site. It was suggested that thinning could improve the structure of forest, leading to restoring the effluent (runoff and groundwater) pH to the normal value.