Effects of decomposed leaf litter mixtures from Platycladus orientalis and broadleaf tree species on soil properties

Determining the effects of decomposed leaf litter mixtures, consisting of litter from different tree species, on the properties of soil is important for evaluating nutrient cycling and interspecific relationships. In this study, leaf litter mixtures consisting of Platycladus orientalis (L.) Franco combined individually with eight broadleaf plant species were ground and mixed with soil to analyze the effects of their decomposition on the quantity of soil microbes, the activities of soil enzymes, and the soil chemical properties and to determine the interactions between the different types of litter within a mixture during decomposition. In terms of soil properties as a whole, we found that when P. orientalis litter was mixed separately with litter from Amorpha fruticosa L., Caragana microphylla Lam., Betula platyphylla Suk., or Hippophae rhamnoides L., the resulting litter mixtures showed synergistic interaction effects on soil, but when P. orientalis litter was mixed with litter from Populus simonii Carr., Ulmus pumila L., Robinia pseudoacacia L., or Quercus liaotungensis Koidz. showed antagonistic interaction effects.     

冀北山地不同树种组成桦木林枯落物及土壤水文效应

为弄清不同树种组成的林分对林地枯落物及土壤持水能力的影响,采用浸泡法和双环法对冀北山地5种不同树种组成的桦木林进行研究,结果表明:1林地枯落物半分解层储量均大于未分解层,总储量变化范围为12.85~20.87t/hm~2,白桦纯林储量最大,阔叶混交林最小;2枯落物最大持水量变化范围为73.27~106.99t/hm~2,有效拦蓄量变化范围为59.22~81.86t/hm~2,均为杨桦混交林最大、落桦混交林最小;3枯落物持水量与浸泡时间呈对数关系,随时间推移逐渐增大,而吸水速率与浸泡时间呈指数关系,随浸泡时间推移而逐渐下降;4土壤容重是油松白桦林最大、杨桦混交林最小,总孔隙度是杨桦混交林最大(60.66%)、阔叶混交林次之(59.31%)、油松白桦林最小(45.43%),土壤最大持水量和有效持水量均是杨桦混交林最大、阔叶混交林次之、油松白桦林最小;5土壤入渗速率和入渗时间呈明显幂函数关系。综合来看,杨桦混交林和阔叶混交林枯落物和土壤持水能力较强。     

Impacts of mixed litter decomposition from <Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> and other tree species on C loss and nutrient release in the Loess Plateau of China

The productivity of Robinia pseudoacacia (R.p.) pure forest usually declines at the late growth stage, and reforming it into mixed forests could be a promising way to resolve this problem. When choosing a suitable tree species that can be mixed with R.p., the interspecific relationship is an important issue. Therefore, we gathered the autumn litter fall from R.p. and 10 other species from the Loess Plateau of China were mixed in dual species litterbags (R.p. + each other species) and buried them in soil for a 345 days lab decay incubation. We measured the litter mass loss and nutrient contents to determine whether the nutrient release was affected by mixed species litter decomposition. The impacts of mixed litter decomposition on macro-elements release were more obvious than on micro-elements. The litters with similar substrate quality might show variable impacts on nutrients release in mixed decomposition. The C loss and release of nutrient was improved by descending order when R.p. litter was mixed with Hippophae rhamnoides, Ulmus pumila, Populus simonii, Larix principis-rupprechtii and Quercus liaotungensis (Q.l.). But, except for Q.l., only the other species were recommended as suitable mix-plants for R.p. since promoting a high turnover of the nutrient in the litter compartment and a rapid availability for tree.     

Promotion of germination of coniferous seeds by snow stratification combined with dehydration-rehydration treatment

Five chemical and four non-chemical presowing treatments were tested on seeds of three conifers (Larix principis-rupprechtii Mayr, Pinus sylvestris L. var. mongolica Litv, and Pinus tabulaeformis Carr.). By itself, cold stratification with snow for 60 days did not significantly improve the germination percentage over that of soaking the seed in warm water (45 °C) for 12 hours. However, including either one or two dehydration-rehydration cycles after the cold stratification did improve both the percentage and speed of germination of seed from all three species. Soaking seed for 12 hours in various chemicals (KNO₃, CaCl₂, CuSO₄, KMnO₄ and GA₃) before germination was less effective than the snow stratification followed by double dehydration-rehydration treatments (Chang and Lin, 1989).     

寒温带森林根际土壤微生物量碳氮含量生长季内动态变化

【目的】研究寒温带森林根际土壤微生物量碳氮含量的动态变化,为揭示森林土壤碳氮养分利用机制和碳氮循环提供参考,为研究区森林保护与合理经营提供科学依据。【方法】以我国寒温带针阔混交林为研究对象,选择主要组成树种樟子松、兴安落叶松、白桦和山杨,采用抖落法采集根际和非根际土壤样品,对土壤微生物量碳氮含量动态特征进行研究,探讨不同树种根际土壤微生物量碳氮的富集程度、差异性和生长季变化以及其对土壤营养库的贡献率。【结果】不同树种根际土壤微生物量碳氮含量月际变化差异显著,根际土壤微生物量碳含量波动范围为114.14~451.05 mg ·kg -1 ,氮含量波动范围为40.38~185.00 mg ·kg -1 。根际土壤微生物量碳富集率依次为樟子松(87.99%)>白桦(78.22%)>兴安落叶松(73.14%)>山杨(56.96%),微生物量氮富集率依次为山杨(81.50%)>白桦(77.63%)>樟子松(76.42%)>兴安落叶松(51.40%)。土壤微生物量碳氮比为1.42~5.24,樟子松、兴安落叶松、白桦、山杨根际和非根际土壤微生物量碳氮比生长季变幅分别为1.42~5.24、1.57~3.79、1.67~4.55、1.55~2.59和1.79~3.53,其均值分别为2.64、2.63、2.81、2.11和2.36。根际微生物量碳对土壤有机碳库的贡献率为0.83%~0.95%,微生物量氮对土壤有机氮库的贡献率为3.63%~5.08%。【结论】寒温带针阔混交林主要树种生长季根际土壤微生物量碳氮含量均显著高于非根际,根际效应显著;在生长季末期,针叶树种根际效应相比阔叶树种更为强烈;针叶树种根际土壤微生物量对土壤结构和功能的影响高于阔叶树种。     

杉木凋落物土壤生态功能研究进展

凋落物作为连接植物与土壤的基本载体,在养分循环中起着至关重要的作用。目前国内外的研究主要集中于自然或人工林凋落物的产量、养分含量、能量流动及碳循环等方面,而针对杉木凋落物的土壤生态功能并未深入探究。通过查阅大量文献,在前人研究的基础上,文中简述了杉木凋落物的分解特性,详尽地阐述了杉木凋落物对于土壤物理、化学性质及土壤生物的影响,并在现有研究分析的基础上对今后凋落物研究的方向进行了展望。     

Inhibition of the regeneration of Japanese black pine (<Emphasis Type="Italic">Pinus thunbergii</Emphasis>) by black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis>) in coastal sand dunes

Pine forests are declining because of pine wilt disease and Robinia pseudoacacia, a nitrogen-fixing species, is dominating coastal forests along the Sea of Japan. We examined the effects of R. pseudoacacia on the regeneration of a native pine species, Pinus thunbergii. Two 200 m² plots were set up at the border of a P. thunbergii and R. pseudoacacia-dominated area in a coastal forest. We conducted monthly censuses of emergence, distribution and survival of pine seedlings in the plots from May 2003 to December 2004. Light intensity and soil properties were also measured to analyze the relationships between the survival of pine seedlings and environmental conditions using the Mantel test and the structural equation model. Pinus thunbergii seedlings emerged in spring–early summer and in late autumn. Survival of pine seedlings in the R. pseudoacacia-dominated subplots was less than half that in the pine-dominated subplots. Survival of pine seedlings emerging in May 2003 was significantly reduced by the lower light intensity and higher soil nitrogen in R. pseudoacacia-dominated subplots. The tendency was the same for seedlings emerging from April to May 2004. We concluded that R. pseudoacacia reduced the intensity of light during the growing season and increased the nitrogen content of soil, which resulted in inhibition of the natural regeneration of P. thunbergii.     

Changes in nutrient concentrations and nutrient release in decomposing needle litter in monocultural systems of Pinus contorta and Pinus sylvestris—a comparison and synthesis

Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta) needle litters were compared in terms of nutrient composition and its change during decomposition. Initial nutrient composition differed between the species, with lodgepole pine needle litter having significantly higher concentrations of P, Mg and Mn. However, no difference was found for concentrations of N, Ca or K. Increases in concentrations of N, P and K during decomposition were significant in both litter types. For Ca the pattern of concentration changes followed a quadratic function as decomposition proceeded. Concentrations of Mg and Mn decreased in lodgepole pine needle litter. In Scots pine litter there was also an initial decrease, but it was followed by an increase in most incubations. For both Mg and Mn, changes in concentrations during decomposition differed significantly between species. In the late decomposition stages, concentrations of Mg and Mn became similar in both litter types. Nutrient concentrations generated by the models were compared with those of the humus (F and H) layer in the stands. The model was quite accurate in predicting concentrations of N and P for both species and the concentration of Mg for lodgepole pine. By contrast, it was not accurate in predicting concentrations of Ca and Mn. Nutrient release was estimated for the two species using both measured litterfall data and long‐term estimates, and regression models were used to predict concentration changes. Rates of release of P, Mg and Mn in the lodgepole pine stands were found to be about twice as high compared with those in Scots pine. Calcium was also released to a greater extent although the difference was not significant.     

Indirect effects of precipitation variation on the decomposition process of Mongolian oak (Quercus mongolica) leaf litter

The effect of precipitation variation on the chemistry of Mongolian oak (Quercus mongolica) leaf litters was examined by analyzing litters of Mongolia oak saplings under four precipitation gradients. The decomposing process of these leaf litters in the Mongolian oak dominated forest was assessed using litter bag method. Compared with the litters of the Mongolian oak saplings from the natural precipitation site (A), litters produced by Mongolian oak from the driest precipitation gradient (A₄₅₀) had significantly higher concentrations of nitrogen (N), phosphorus (P) and potassium (K) while lower acid-insoluble fraction (AIF) concentration. The decomposition study showed that A₄₅₀ exhibited significantly higher decomposition rate, mineralization rates of N, P and K as well as much shorter N and P net immobilization periods. On the contrary, litters produced by seedlings from wettest gradient (A₈₅₀) showed a totally opposite pattern. Litters from saplings that received comparable precipitation (A₆₅₀) to those at the natural site (A) had significantly higher N concentration and faster decomposition rate as well as release rates of N, P and K. The mass loss patterns for the four litter types fitted the exponential model and the decay constant (k) can be well predicted by initial AIF/N. During the decomposition period, N concentration was best related to the percentage of mass remaining of the litters with relatively higher AIF concentrations and lower N concentrations, but the percentage of mass remaining of litters with lower AIF concentrations and higher N concentrations correlates strongly with AIF con centration. Our study proved that changes in precipitation significantly altered the litter quality, and therefore indirectly changed the decay process of leaf litters. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(2): 261–266 [译自: 应用生态学报]     

Relation between Growth and Vertical Distribution of Fine Roots and Soil Density in the Weibei Loess Plateau

The influence of woodland soil bulk density on the growth and distribution of fine root system of main planting tree species in the Weibei Loess Plateau was investigated by means of pot culture and field survey. Results indicated that in the woodland of Pinus tabulaeformis, soil bulk density increased with the depth at different sites, while in the woodland of Robinia pseudoacacia, soil bulk density was higher than that in P. tabulaeformis, and there was no clear difference across the profile. Further analysis implied that there existed negative correlations between soil bulk density and fine root length in the woodland of P. tabulaeformis. Results from pot culture indicated that although the effects of pot culture media on the fine root growth and development of different tree species seedlings were different, all treated seedlings grew better in the soil matter with medium bulk density and porosity and with the biggest biomass. Bulk density of pot culture media had clear effects on the growth and development of P. tabulaeformis and R. pseudoacacia seedling roots, especially on the former, whereas it had little effect on that of Platycladus orientalis and Prunus armeniaca var. ansu, whose fine root biomass changed little in different pot culture media. Translated from Scientia Silvae Sinicae, 2004, 40(5) (in Chinese)     

Appropriate density of water and soil conservation of Pinus tabulaeformis and Robinia pseudoacacia forests in loess area, North China

In this paper, based on a long-term monitoring of water cycle in the water and soil conservation forest stands of Pinus tabulaeformis and Robinia pseudoacacia, the soil moisture deficit is calculated. Following the principles of runoff-collecting forestry and applying the forest structure investigation results, the authors developed a formula to calculate appropriate density for forests on the basis of different diameters at breast height (DBH). Using this method to manage forests, the natural water requirement of forests can be met and soil drought can be avoided. In addition, with long-term monitoring of soil moisture in stands, the authors also give an appropriate managing density specifically for the water and soil conservation forests of P. tabulaeformis and R. pseudoacacia in the loess area which is according to soil moisture content, or with the lowest soil moisture content and invalid moisture frequency as the indexes. __________ Translated from Science of Water and Soil Conservation, 2007, 5(2): 55–59 [译自: 中国水土保持科学]     

樟子松人工林混交改造后土壤养分综合评价

为探明不同混交模式对土壤养分的影响机制,以38 a生的樟子松人工林为研究对象,对其进行带状间伐后,在间伐带内栽植樟子松、银中杨、色木槭幼苗形成混交林。应用典范对应和主成分分析方法,比较混交林土壤化学性质、酶活性的差异及对应关系,结果表明:混交改造后土壤化学性质均高于对照,其中有机质、碱解氮含量在樟×槭(PAM2)、樟×杨(PPM2)样地达到最高,分别为14.74 g/kg和49.63 mg/kg,但有效磷含量则低于樟×樟样地;与对照相比,各样地土壤酶活性均出现了不同程度的升高,其中樟×杨样地土壤酶活性表现最好。总的来说,混交样地的土壤养分因子综合得分高于对照,针阔混交林普遍高于樟子松异龄林。因此,营建混交林是促进科尔沁沙地樟子松人工林土壤生态改善,延长防护林生命周期的行之有效的办法。     

Concentrations of foliar and surface soil in nutrientsPinus spp. plantations in relation to species and stand age in Zhanggutai sandy land, northeast China

The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, total P and C: N ratio of the soil inP. sylvestris var.mongolica stands were significantly higher in comparison with those inP. tabulaeformis andP. densiflora stands. ForP. sylvestris var.mongolica, the foliar P concentration appeared to decrease with age, and the foliar N and K concentrations did not show a consistent change with age. As for the different tree species of the similar age, the foliar N and P concentrations were significantly different (p<0.05), being withP. sylvestris var.mongolica>P. densiflora>P. tabulaeformis. The foliar N: P ratio ofP. densiflora significantly was higher thanP. sylvestris var.mongolica andP. tabulaeformis, while the foliar K was no obvious difference between the three tree species. There were significant correlation (p<0.05) between soil total N and P, soil organic matter and total P, foliar N and P, but it did not show significant correlations between soil and foliar nutrient concentrations, which might attribute to the excessive litter raking, overgrazing and low soil moisture in this area. Based on the foliar N: P ratio, we introduced a combination threshold index of N: P ratio with their absolute foliar nutrient concentrations to determine the possible limiting nutrient. According to the critical N: P ratio and their absolute foliar N, P concentrations, theP. sylvestris var.mongolica stands showed a decreased N limitation degree with age, theP. densiflora stands showed unlimited by N and P in the whole, and theP. tabulaeformis stands showed co-limited by N and P. No significant difference in soil nutrient concentrations of the surface soils was found between 45, 29, 20-yr-oldPinus sylvestris var.mongolica plantation stands. Foundation item: This research was supported by Key Knowledge Innovation Project (KZCX3-SW-418) of Chinese Academy of Sciences. Biography: CHEN Guang-sheng (1978-), male, master candidate in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China Responsible editor: Song Funan     

不同类型樟子松林分土壤养分空间变异性的初步研究

就樟子松纯林和樟子松落叶松混交林下的土壤主要养分的含量、性质进行研究,探讨不同林型下土壤养分含量的变异性以及土壤各指标之间的相关关系,揭示研究区域内森林生态系统土壤养分空间分布特征和变异的某些规律。结果表明,樟子松纯林和樟子松落叶松混交林下土壤pH值变异系数为4.22～5.90,属弱变异性;樟子松纯林下层土壤的有效磷含量变异系数达到90.97%,属于强变异性,其他所测的土壤养分指标变异系数在16.38%～50.89%,均属于中等程度变异性。     

彰武北部沙地土壤钾素状况的研究

对彰武县北部沙地不同利用类型立地的土壤钾素状况的研究表明:彰武县北部沙地土壤全钾含量处于较高水平,速效钾、缓效钾含量仅杨树纯林及樟子松、油松和樟子松、杨树混交林为较高水平,而大面积的樟子松林和农业用地均为较低水平.     

Effects of different vegetation restoration models on soil microbial biomass in eroded hilly Loess Plateau, China

Vegetation restoration is a key measure to improve the eco-environment in Loess Plateau, China. In order to find the effect of soil microbial biomass under different vegetation restoration models in this region, six trial sites located in Zhifanggou watershed were selected in this study. Results showed that soil microbial biomass, microbial respiration and physical and chemical properties increased apparently. After 30 years of vegetation restoration, soil microbial biomass C, N, P (SMBC, SMBN, SMBP) and microbial respiration, increased by 109.01%–144.22%, 34.17%–117.09%, 31.79%–79.94% and 26.78%–87.59% respectively, as compared with the farmland. However, metabolic quotient declined dramatically by 57.45%–77.49%. Effects of different models of vegetation restoration are different on improving the properties of soil. In general, mixed stands of Pinus tabulaeformis-Amorpha fruticosa and Robinia pseudoacacia-A. fruticosa had the most remarkable effect, followed by R. pseudoacacia and Caragana korshinkii, fallow land and P. tabulaeformis was the lowest. Restoration of mixed forest had greater effective than pure forest in eroded Hilly Loess Plateau. The significant relationships were observed among SMBC, SMBP, microbial respiration, and physical and chemical properties of soil. It was concluded that microbial biomass can be used as indicators of soil quality. __________ Translated from Journal of Natural Resources, 2007, 22(1): 20–27 [译自: 自然资源学报]     

我国樟子松人工林天然更新研究进展

樟子松人工林天然更新问题的研究一直在进行,但人工林内幼苗数量过少及难以发育为幼树的问题一直难以彻底解决。文中综述了影响我国沙地樟子松人工林天然更新能力的因素,如光照、温度、水分、土壤环境、生物因子及人工营林技术等的研究概况。在研究过程中发现,樟子松人工林的遗传多样性与土壤微生物对樟子松人工林天然更新影响方面的研究尚少有报道,或可以为解决樟子松人工林天然更新问题提供更深入的思路。     

马尾松与几种阔叶树混交后水源涵养功能的变化

通过对马尾松与山杜英、枫香、拟赤杨和光皮桦混交后水源涵养功能的研究,结果表明:地上部分持水量以马尾松纯林最大,其次是混交林,最小为阔叶树纯林;活地被物枯落物部分持水量以阔叶树纯林最大,其次为混交林,最小为马尾松纯林;土壤渗透能力和贮水能力以混交林最大,其次为阔叶林,最小为马尾松林。     

Studies on the diversity of soil animals in Taishan Mountain

Taishan Mountain has diverse habitats and abundant groups of soil animals. Five habitats,Platycladus orientalis forest,Pinus densiflora forest,Robinia pseudoacacia forest,Pinus tablaerormis forest and Grassland, were selected and the diversity of soil animals in different habitats in Mt. Taishan were investigated and studied in 1997–1999. Totally 52 groups of soil animals were found, belonging separately to 7 Phyla, 11 Classes, 25 Orders and 28 suborders or families. There exists remarkable difference in groups, quantity and diversity of soil animals among the five habitats. Grassland habitat was the highest andPinus densiflora forest was the lowest in groups, quantities, Density-group index (DG) and Diversity index of comparing many communities (DIC) of soil animals. Shannon-Wiener’s diversity index (H′) for soil animals of different habitats was in order ofPlatycladus orientalis forest>Pinus densiflora forest>Pinus tablaerormis forest>Grassland>Robinia pseudoacacia forest, Pielou’s equality index (J′) wasPlatycladus orientalis forest>Pinus densiflora forest>Grassland>Pinus tablaerormis forest>Robinia pseudoacacia forest, and Simposn’s dominant index (C) was Grassland>Robinia pseudoacacia forest>Pinus tablaerormis forest>Pinus densiflora forest>Platycladus orientalis forest. The H index and J index of macro-soil animal all were larger than that of mid-small soil animal. Clustering analysis for five soil animal communities and ordination analysis for community structure by multidimensional scaling (MDS) were made and completely identical results were obtained. Soil animal communities of five habitats were divided into 3 groups. Biography: Y{upuan} Xing-zhong (1963-), male, associate professor of East China Normal University, Shanghal 200062, China Responsible editor: Chai Ruihai     

Impacts of mixed litter decomposition from Robinia pseudoacacia and other tree species on C loss and nutrient release in the Loess Plateau of China

The productivity of Robinia pseudoacacia(R.p.) pure forest usually declines at the late growth stage,and reforming it into mixed forests could be a promising way to resolve this problem. When choosing a suitable tree species that can be mixed with R.p., the interspecific relationship is an important issue. Therefore, we gathered the autumn litter fall from R.p. and 10 other species from the Loess Plateau of China were mixed in dual species litterbags(R.p.+each other species) and buried them in soil for a 345 days lab decay incubation. We measured the litter mass loss and nutrient contents to determine whether the nutrient release was affected by mixed species litter decomposition. The impacts of mixed litter decomposition on macro-elements release were more obvious than on micro-elements. The litters with similar substrate quality might show variable impacts on nutrients release in mixed decomposition. The C loss and release of nutrient was improved by descending order when R.p. litter was mixed with Hippophae rhamnoides, Ulmus pumila, Populus simonii, Larix principis-rupprechtii and Quercus liaotungensis(Q.l.). But, except for Q.l., only the other species were recommended as suitable mix-plants for R.p. since promoting a high turnover of the nutrient in the litter compartment and a rapid availability for tree.