章古台沙地不同树种年龄和树种的生态系统叶片和土壤养分研究

对辽宁省章古台地区的几种主要针叶树种的针叶养分及其林分表层(0-15cm)土壤养分进行研究。结果表明,不同年龄樟子松(45、29和20年)(Pinussylvestrisvar.mongolica)林地表层土壤养分并无显著差别,而29年樟子松林分表层土壤全N、全P和N:P比显著高于相近年龄的赤松(P.densiflora)(29年)和油松林(P.tabulaeformis)(31年)。随着樟子松年龄的增加,叶片P含量逐渐减少,而叶片N和K含量则未表现出随年龄而变化的趋势;对于年龄相近的三个树种,叶片N和P含量表现为:樟子松>赤松>油松,而叶片K含量在三个树种中并无显著差别。表层土壤的全N和全P,有机质和全P以及叶片N和P含量之间表现出了显著的相关性,但是,林分表层土壤养分和树木针叶养分之间并无显著相关关系,这可能与当地对凋落物的过度收集,过度放牧以及土壤水分含量低有关。最后,根据国外研究结果引入N:P比阈值来分析研究区域的N,P养分状况,基于章古台地区这几种针叶树种针叶N:P比,我们认为研究区域的樟子松随着年龄的增加受N限制的可能性降低,29年的赤松林整体表现出不受N和P养分限制,而31年的油松林则表现为系统N和P都供应不足。图3表3参45。     

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     

沙地樟子松天然林和人工林中针叶养分含量比较

为了诊断沙地樟子松人工林的衰退原因,我们比较分析了沙地樟子松天然林和人工林中的叶片养分含量。结果表明,天然林中的樟子松叶片内氮、磷含量均比人工林中低,而钾含量比人工林高。樟子松人工林叶片中 N:P, P: K 和N: K在45年前随年龄增加而增加,从植物养分含量的角度来看,这一结果表明氮或磷可能不是沙地樟子松生长的绝对限制因子。然而,天然林和人工林叶片中的钾含量比以前报道过的松属植物中的含量都要低。天然林叶片中的N: P比值在正常的范围内,但人工林的则在该范围以外。这些结果表明天然林具有比人工林更好的养分平衡状况。如果只从樟子松的生长地来考虑,我们可以认为樟子松人工林的衰退现象可能是因其它的矿物元素或者氮和磷的有效性,而不是氮和磷的绝对含量不足造成的。养分的不平衡状况和人工林内针叶快速分解可能也是衰退的重要因素。图3表3参42。     

叶面施肥对杉木苗期生长的影响研究

为了解叶面肥对杉木Cunninghamia lanceolate苗期生长质量的影响,对杉木苗分别喷施1.000 g·L~(-1)特多收和0.167 g·L~(-1)喷施宝叶面肥,结果表明:2种叶面肥处理3个月后杉木苗高度、干重量以及Ⅰ级苗比例与清水处理差异极显著(P0.01),地径差异显著(P0.05),特多收叶面肥处理较喷施宝叶面肥处理苗高、地径、干重量和Ⅰ级苗比例分别增加6.11%、5.17%、24.85%和7.02%,效果优于喷施宝。     

Comparison of foliar nutrient concentrations between natural and artificial forests of Pinus sylvestris var. mongolica on sandy land, China

In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.     

叶面肥对油茶幼苗生长和生理特征影响的研究

以1a生出圃的油茶幼苗为材料研究不同浓度无机盐配比的叶面肥对油茶幼苗生长发育的影响,以便获得有利于油茶幼苗生长的叶面肥.在N、P、K肥的基础上,对硼酸、硫酸锌、钼酸钠进行L9(34)正交试验设计来配制叶面肥,喷施油茶幼苗叶片一段时间后测定幼苗的生长及其生理生化指标,对测定结果进行了极差分析和方差分析,并对优化的叶面肥进...     

两种叶面肥对马尾松苗期生长的影响研究

为了解叶面肥种类对马尾松(Pinus massonianna)苗期生长质量的影响,对马尾松苗分别喷施质量浓度为1g.L-1的特多收和0.125 g·L-1喷施宝叶面肥,结果表明:2种叶面肥处理3个月后马尾松苗高、地径、根系生长以及苗木质量较清水处理均有所提高,特多收叶面肥处理各生长指标均显著高于清水处理(P＜0.05),特多收叶面肥处理较喷施宝叶面肥处理的苗高、地径、主根长、须根数、总须根长、鲜质量和Ⅰ级苗比例分别增加0.7％、3.1％、17.6％、29.5％、21.4％、1.6％和1.5％,施肥效果优于喷施宝(P＜0.05).     

Effects of serpentine soil factors on Virginia pine (Pinus virginiana) seedlings

Effects of simulated serpentine soil conditions (elevated Mg:Ca ratio and Ni concentration) on seedlings from populations of Virginia pine (Pinus virginiana Mill.) from serpentine and non-serpentine sites were evaluated in sand culture. We determined (1) how seedlings are affected by elevated Mg:Ca ratio and Ni concentrations, (2) if there are interactive effects between Mg:Ca ratio and Ni concentrations on seedling growth, needle pigment concentrations, and nutrition, and (3) if Virginia pine populations from serpentine areas are edaphic ecotypes. A Mg:Ca ratio of 5 and 50 microM Ni both reduced seedling growth compared with control seedlings grown in the presence of the standard Mg:Ca ratio of 0.5 and no Ni. Interactive effects between Mg:Ca ratio and Ni concentrations were highly significant for growth, foliar pigments, and needle and root elemental concentrations. Nickel-mediated reductions in growth and foliar pigment concentrations were less at the serpentine Mg:Ca ratio of 5 than at the standard (non-serpentine) Mg:Ca ratio of 0.5. Foliar N was reduced by Ni concentrations as low as 10 microM, and foliar and root K, Ca and P concentrations were significantly reduced by Ni concentrations above 25 microM, with greater reductions at a Mg:Ca ratio of 0.5 than at a Mg:Ca ratio of 5. There were no population x serpentine soil factor interactions for seedling growth, foliar pigment concentrations, or nutrition, suggesting that seedlings from trees growing on serpentine soils are not edaphic ecotypes. We conclude that serpentine conditions present at the site of seed collection have not resulted in the selection of edaphic ecotypes of Virginia pine with respect to Mg:Ca ratio and Ni concentration.     

Growth and nutrient use efficiency of water tupelo seedlings in flooded and well-drained soil

Growth characteristics and nutrient utilization rate of Nyssa aquatica L. seedlings grown in pots containing flooded or well-drained soil were compared in a greenhouse study. For most of the growing season, relative height and diameter growth rates, and biomass accumulation rates were greater for seedlings in flooded soil than for seedlings in well-drained soil. The concentration of Fe in the roots of seedlings in flooded soil was almost tenfold greater than that of seedlings in well-drained soil. However, flooding had no effect on foliar Fe concentrations. The flooding treatment resulted in decreased concentrations of N in all component parts and increased concentrations of P in the roots and stem, but it had no effect on foliar P concentrations. In response to flooding, foliar K concentrations decreased, whereas the concentration of K in the roots increased. Flooding had no effect on the K concentration of the stem. Seedlings in flooded soil produced more total biomass per milligram of nutrient absorbed than seedlings in well-drained soil, suggesting that N. aquatica seedlings are more efficient at producing biomass and height growth under hydric conditions than under mesic conditions.     

Autumn Fertilization in the Nursery Affects Growth of Picea abies Container Seedlings After Transplanting

Second-year Norway spruce seedlings [Picea abies (L.) Karst.] grown in containers were divided into three fertilization levels in August [5, 15 and 25 mg nitrogen (N) seedling^?1]. The resulting foliar concentrations of N were 11.0, 13.1 and 15.8 g kg^?1, respectively. Seedling height (mean 26.0 cm) did not differ among treatments. The next spring, the seedlings were tested in two experiments. (1) The seedlings were transplanted into pots containing sandy soil in the greenhouse, where they were fertilized with either pure water or nutrient solution (22 mg N l^?1). (2) The outplanting performance of the autumn-fertilized seedlings was tested on a sandy field. In the greenhouse experiment, the autumn fertilization level affected height growth and root egress of the seedlings significantly, but less than fertilization with a nutrient solution after planting. In the field experiment, during the first season after transplanting shoot growth of the seedlings increased with the level of autumn fertilization. After the second and third seasons, the seedling stem volume was highest with the highest level of autumn fertilization. These results suggest that, by improving the preplanting nutrient status of seedlings, the growth of shoot, stem diameter and root biomass can be enhanced after planting, especially on nutrient-poor soils. However, heavier autumn fertilization than that used here may yield a greater and more persistent increment in growth.     

The effect of fertilization on early growth of konara oak and Japanese zelkova seedlings planted in a harvested pitch pine plantation

We determined a suitable amount of fertilizer for konara oak(Quercus serrata) and Japanese zelkova(Zelkova serrata) planted in a harvested pitch pine(Pinus rigida) plantation. Two-year-old bare-root seedlings of konara oak and one-year-old containerized seedlings of Japanese zelkova were planted in April 2011. Three plots were established for each tree species to evaluate each of three fertilization applications. Solid compound fertilizer(N:P:K = 3:4:1) was applied yearly in three amounts(control: no fertilization, F1: 180 kg ha-1, and F2:360 kg ha-1), every May from 2011 to 2013. We measured the root collar diameter and height, and analyzed the compartmental N and P concentrations. Compartmental N concentrations of konara oak and Japanese zelkova were not consistent based on amount of fertilization. However,the compartmental P concentrations of konara oak and Japanese zelkova were significantly different in the order of F2, F1, and control. Although the differences in growth of konara oak appeared after 3 years of fertilization,Japanese zelkova showed differences after only 2 years of fertilization owing to differences in seedling type. Growth of konara oak was affected by fertilization at F1 and F2 in2013. However, growth of Japanese zelkova was affected only at F2. Nutrient demand of Japanese zelkova appeard to be higher than that of konara oak, at least during the early growing period. Results from this study could be practically used in harvested pitch pine plantations to determine appropriate fertilization regimes.     

Long-term trends of phosphorus nutrition and topsoil phosphorus stocks in unfertilized and fertilized Scots pine (Pinus sylvestris) stands at two sites in Southern Germany

For two Scots pine (Pinus sylvestris) ecosystems in S Germany with different atmospheric N deposition (Pfaffenwinkel, intermediate N deposition; Pustert, large N deposition), the supply with phosphorus (P) has been monitored for unfertilized and fertilized plots over more than four decades by foliar analysis (1964–2007). Additionally, topsoil concentrations and stocks of total P and plant-available P (citric-acid-extractable phosphate) were quantified in 10-year intervals (1982/1984, 1994, 2004). At both sites, fertilization experiments, including the variants control, NPKMgCa + lime, PKMgCa + lime + introduction of lupine, corresponding to an addition of 75 and 90 kg ha⁻¹ P in Pustert and Pfaffenwinkel, respectively had been established in 1964. Our study revealed different trends of the P nutritional status for the pines at the two sites during the recent four decades: At Pustert, elevated atmospheric N deposition together with small topsoil P pools resulted in significant deterioration of Scots pine P nutrition and in an increasingly unbalanced N/P nutrition. At Pfaffenwinkel a trend of improved P nutrition from 1964 to 1991 was replaced by an opposite trend in the most recent 15 years. For our study sites, which are characterized by acidic soils with thick O layers, the forest floor stock of citric-acid-extractable phosphate showed a strong and significant correlation with the P concentration in current-year pine foliage, and thus was an appropriate variable to predict the P nutritional status of the stands. Total P stocks as well as the concentrations of total P in the forest floor or in the mineral topsoil were poorly correlated with pine foliar P concentrations and thus inappropriate predictors of P nutrition. P fertilization in the 1960s sustainably improved the P nutritional status of the stands. At Pfaffenwinkel, foliar P concentrations and topsoil stocks of citric-acid-extractable phosphate were increased at the fertilized plots relative to the control plots even 40 years after fertilization; at Pustert, foliar P concentrations were increased for about 20 years.     

土壤温度和水分变化对川西云杉幼苗氮和磷含量的影响

【目的】研究不同梯度的土壤温度和水分对川西云杉幼苗生长性状和各器官氮和磷含量的影响,以期为全球气候变暖背景下解释川西云杉树线形成的原因提供参考和数据积累。【方法】以5年生川西云杉幼苗为试验材料,采用人工气候室结合嵌套设计,设置5个土壤温度梯度(2、7、12、17、22℃)和3个土壤水分梯度(干旱处理、正常水分含量处理、饱和水分含量处理)。每处理9株幼苗,共135株幼苗。实验处理4个月后,测定并比较分析不同梯度的土壤温度和水分对幼苗的生长性状、各器官干物质含量、各器官全氮、全磷浓度和含量以及土壤全氮和全磷浓度的影响。【结果】土壤温度处理对幼苗基径和株高生长量均无显著影响,而土壤水分处理对幼苗株高生长量有显著影响;在2℃和7℃土壤温度干旱处理下显著降低了幼苗的株高生长量,但随着土壤温度的升高其影响效应不显著。土壤温度处理对土壤氮和磷浓度无显著影响,而干旱处理显著升高了土壤氮和磷浓度。川西云杉幼苗各器官的氮和磷浓度以及当年生叶氮含量随土壤温度降低显著降低;干旱和饱和水分处理显著降低了当年生叶和当年生枝的氮浓度,饱和水分处理显著降低了当年生叶的磷浓度,干旱处理显著降低了当年生枝、茎和根的磷浓度,干旱和饱和水分处理显著降低了当年生叶和根的氮和磷含量,且随着土壤温度升高影响效应更显著。【结论】在短期内,土壤低温对川西云杉幼苗的生长性状没有明显的制约作用,但对川西云杉幼苗各器官的氮和磷浓度及含量影响显著,尤其是当年生叶和根的氮和磷浓度及含量。在川西地区,低温、干旱等极端气候胁迫导致的云杉幼苗氮、磷含量的不足很可能是限制川西云杉垂直分布的重要因素。此外,土壤温度和水分处理存在显著的交互作用,随着土壤温度的降低,水分胁迫对幼苗各器官氮和磷含量的影响由显著变得不再显著,说明随着海拔升高,与水分因子相比,土壤低温成为造成云杉各器官营养元素亏缺的主导因子。     

Growth and Nutritional Responses of Juvenile Jeffrey Pine to Post-Planting Fertilization

Abstract

Broadcast fertilization of a three-year-old Jeffrey pine (Pinus jeffreyi Grev. & Balf.) plantation growing on an eroded Sierra Nevada site was examined for its capacity to enhance seedling growth. The amendments chosen for the study included controlled release and conventional soluble formulations that contained a variety of N forms, but all featured high N content along with other nutrients. Four application rates were used, and all amendments were distributed around the base of the seedlings as top dressing. Four seasons after treatment application, fertilized seedlings were 129% larger in height, 93% larger in diameter, and 865% greater in shoot volume than unfertilized seedlings overall. Seedling sizes generally increased with application rate, and by a small margin, the controlled release fertilizer outperformed the other formulations. Relative growth analysis suggested that stimulation by the amendments would continue beyond four seasons. Foliar analysis conducted early and again late during the study revealed that N and P concentrations were consistently raised by fertilization, which likely accounts for much of the accompanying growth gains, while Ca, Fe, Mn, B, and Al concentrations were consistently reduced. Either early or late, foliar K was also raised while Mg, S, Zn, and Cu were reduced. Collectively, these results indicate that fertilization with a variety of high N formulations can increase the availability and uptake of critical nutrients sufficiently to impart in Jeffrey pine on low quality sites a substantial growth advantage.     

Nutritional Augmentation of Jeffrey Pine Saplings on a Harsh Sierran Site

Broadcast fertilization with an array of amendments was examined for its capacity to reinvigorate growth and enhance nutrition of a 12-yr-old Jeffrey pine (Pinus jeffreyi Grev. & Balf.) plantation growing on an acidic Sierra Nevada surface mine site. Selected amendments consisted of Viking Brand 21-7-14, Free Flow 29-3-4, High N 22-4-6 + Minors, and Milorganite 6-2-0 + Iron—formulations that differed substantially in critical characteristics including N sources and the duration of release, and each was administered using three rates of application. All formulations stimulated sapling growth during some stage of the study, especially when applied at the highest rates, but the Free Flow amendment, which features urea as the predominant N source, the High N formulation, which is a controlled release fertilizer, and Milorganite, an organic amendment based on municipal biosolids, sustained growth enhancement longer than the Viking amendment, which relies exclusively upon ammoniacal and nitrate N forms and lacks any provision for metering nutrient release. As indicated by foliar analysis, increased availability and uptake of N probably accounted for most of the added growth induced by fertilization, although improved P nutrition likely contributed as well. However, in addition to the N and P responses, fertilized saplings were frequently lower in Mn, B, and Al—all of which may be phytotoxic at elevated concentrations. Further support for the possible linkages between foliar concentrations noted above and sapling growth responses were provided by the concentrations of these elements in the mine soil, which was low in N and P but high in Mn, B, and Al. This study reports approaches to nutritional augmentation on degraded sites suitable for use during the sapling stage of tree development.     

Genetic variation in foliar nutrient concentration in relation to foliar carbon isotope composition and tree growth with clones of the F1 hybrid between slash pine and Caribbean pine

The objectives of this study were: (1) to quantify the genetic variation in foliar nutrient concentration in relation to foliar carbon isotope composition (δ¹³C) and tree growth of 122 clones of ca. 4-year-old F₁ hybrids between slash pine (Pinus elliottii Engelm var. elliottii) and Caribbean pine (P. caribaea var. hondurensis Barr. et Golf.) grown at two experimental sites with different water and nutrient availability in southeast Queensland, Australia and (2) to examine the potential of using foliar nutrient concentration of the 4-year-old tree canopies for selecting elite F₁ hybrid pine clones with improved nutrient-use efficiency (NUE) and water-use efficiency (WUE), and ultimately enhanced tree growth under ambient growing conditions. There were significant differences in foliar nutrient concentrations between two canopy positions (upper outer and lower outer canopy) sampled, between summer and winter, and between the two sites. This highlights that foliar nutrient concentrations are influenced by sampling and environment. Significant genetic variations in foliar nutrient concentrations were detected between the clones, between the female parents, and between the male parents of the clones in both sampling seasons at both sites. Depending on the nutrient concerned, canopy position, season, and site sampled, the clones accounted for 4.7–33.9% of the total variation in foliar nutrient concentrations, the clone female parents for 0–25.1% and the clone male parents for 0–28.6%. The site-by-clone interactions were statistically significant for foliar N, P, Mg, Cu, Zn, Mn, Fe and mineral concentrations at the upper outer canopy in summer, and for foliar N concentration in winter. There were significant, positive correlations between clone means of foliar δ¹³C and N concentration at the upper outer canopy in summer for the wet site, while clone foliar δ¹³C was also positively related to clone foliar N concentration at both canopy positions in summer for the dry site. This suggests that clone WUE as reflected in foliar δ¹³C may be improved by selecting elite clones with higher foliar N concentration and increased photosynthesis, leading to enhanced tree growth when both water and N are the major growth-limiting factors. This is supported by the positive correlation detected between clone tree height and foliar N concentration at the upper outer canopy for both sites. Thus, foliar nutrient (particularly N) concentration, together with foliar δ¹³C, may be useful for assisting in selection of exotic pine clones with improved NUE and WUE, and enhanced tree growth under the nutrient- and water-limiting environments.     

Impacts of mechanical site preparation on foliar nutrients of planted white spruce seedlings on mixed-wood boreal forest sites in Alberta

The impacts of different methods of mechanical site preparation (MSP) on performance and foliar nutrition of planted white spruce (Picea glauca (Moench) Voss) seedlings were examined at two mixed-wood boreal forest sites (Judy Creek, Fox Creek) in Alberta, Canada. The treatments included three types of MSP: disc trench, ripper plough, and bladed, the latter including thin and thick microsites (based on depth of remaining organic matter); as well as a harvested-control (no MSP). Seedlings were planted in June 1991, four months after MSP, and foliar N, P, K, Ca, Mg, S, Mn, Fe, and Al were assessed in the second and third growing seasons (13, 25, and 28 months later). Nutrient concentration and relative (among treatments) foliar nutrient content scaled up to the level of the whole seedling were examined. Following analysis of variance, significant responses were interpreted using vector analysis. MSP did not significantly affect seedling survival, height or unit needle weight. There was a non-significant trend of higher foliar biomass for seedlings in MSP areas than for control seedlings. Overall, the impact of MSP on foliar nutrient status on these sites was minimal. The only consistent positive effect of MSP on seedling nutrition was increased foliar Mg concentrations in blade-thin sites at Fox Creek. Indications of possible negative impacts of MSP include: increased Fe and Al concentrations in MSP areas at both sites; reduced P and K concentrations at both sites; and reduced Mn concentration and content at one site. The ripper treatment had the greatest positive effect on foliar nutrient status (P, K, Mn concentration). Blading (particularly blade-thin) resulted in the lowest concentrations of foliar P, K and Mn and the greatest increases in foliar Fe and Al.     

Relationships between foliar phosphorus fractions of Pinus sylvestris var. mongolica and soil available phosphorus

In order to find out the best foliar diagnostic index of phosphorus (P) nutrition in Mongolian pine (Pinus sylvestris var. mongolica) in the southeastern Keerqin Sandy Lands, the concentrations of total nitrogen (N), inorganic P, organic P and total P in needles of different ages and soil available P were examined. The results show that in the study area, soil available P was rather low (0.12–0.63 mg/kg) and was significantly correlated with inorganic P (cPi) and total P (cPt) concentrations in current year needles of Mongolian pine. The significant correlation between soil available P and needle cPt derived from the significant correlation between cPi and cPt. Compared with cPt, cPi did reflect the level of soil P supply more accurately and more directly. __________ Translated from Chinese Journal of Applied Ecology, 2008, 19(3): 494–498 [译自: 应用生态学报]     

Growth response of Douglas-fir seedlings to nitrogen fertilization: importance of Rubisco activation state and respiration rates

High foliar nitrogen concentration ([N]) is associated with high rates of photosynthesis and thus high tree productivity; however, at excessive [N], tree productivity is reduced. Reports of excessive [N] in the Douglas-fir forests of the Oregon Coast Range prompted this investigation of growth and needle physiological responses to increasing foliar N concentrations in 1-year-old Douglas-fir seedlings. After 1 year of N fertilization, total seedling biomass increased with each successive increase in N fertilizer concentration, except in the highest N fertilization treatment. Of the many physiological responses that were analyzed, only photosynthetic capacity (i.e., Vcmax), respiration rates and leaf specific conductance (KL) differed significantly between N treatments. Photosynthetic capacity showed a curvilinear relationship with foliar [N], reaching an apparent maximum rate when needle N concentrations exceeded about 12 mg g(-1). In vitro measurements of ribulose-1,5-bisphosphate carboxylase (Rubisco) activity suggested that photosynthetic capacity was best related to activated, not total, Rubisco content. Rubisco activation state declined as foliar [N] increased, and based on its significant correlation (r2= 0.63) with foliar Mn:Mg ratios, it may be related to Mn inactivation of Rubisco. Respiration rates increased linearly as foliar N concentration increased (r2= 0.84). The value of K(L) also increased as foliar [N] increased, reaching a maximum when foliar [N] exceeded about 10 mg g(-1). Changes in K(L) were unrelated to changes in leaf area or sapwood area because leaf area to sapwood area ratios remained constant. Cumulative effects of the observed physiological responses to N fertilization were analyzed by modeling annual net CO2 assimilation (Anet) based on treatment specific values of Vcmax, dark respiration (Rdark) and KL. Estimates of Anet were highly correlated with measured total seedling biomass (r2= 0.992), suggesting that long-term, cumulative effects of maximum Rubisco carboxylation, Rdark and KL responses to N fertilization may limit seedling production when foliar N exceeds about 13 mg g(-1) or is reduced to less than about 11 mg g(-1).     

竹酢液对杉木苗木生长效应和土壤肥力影响的研究

通过杉木幼苗的盆栽试验,采用喷施及土壤施入两种施用方法及9个不同浓度处理,分析施用竹酢液后对土壤化学性质以及杉木苗高和地径生长的影响。结果表明:施用竹酢液后,土壤pH无明显变化;H50和P300两种处理可以明显提高土壤全氮和速效磷含量,降低苗木生长过程中土壤速效钾、碱解氮和有机质等指标含量的衰减程度;促进土壤脲酶、多酚氧化酶和过氧化物酶的活性;对苗高和地径的生长有明显的促进作用。总体看来,适宜浓度的竹酢液对提高杉木人工林土壤肥力,促进杉木生长有利,其应用前景广泛。