Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Carbon sequestration by forests and soils on mined land in the Midwestern and Appalachian coalfields of the U.S.

Carbon (C) accreditation of forest development projects is one approach for sequestering atmospheric CO₂, under the provisions of the Kyoto protocol. The C sequestration potential of reforested mined land is not well known. The purpose of this work was to estimate and compare the ecosystem C content in forests established on surface, coal-mined and non-mined land. We used existing tree, litter, and soil C data for fourteen mined and eight adjacent, non-mined forests in the Midwestern and Appalachian coalfields to determine the C sequestration potential of mined land reclaimed prior to the passage of the Surface Mining Control and Reclamation Act (1977). We developed statistically significant and biologically reasonable models for ecosystem C across the spectrum of site quality and stand age. On average, the highest amount of ecosystem C on mined land was sequestered in pine stands (148 Mg ha⁻¹), followed by hardwood (130 Mg ha⁻¹) and mixed stands (118 Mg ha⁻¹). Non-mined hardwood stands sequestered 210 Mg C ha⁻¹, which was about 62% higher than the average of all mined stands. Our mined land response surface models of C sequestration as a function of site quality and age explained 59, 39, and 36% of the variation of ecosystem C in mixed, pine, and hardwood stands, respectively. In pine and mixed stands, ecosystem C increased exponentially with the increase of site quality, but decreased with age. In mined hardwood stands, ecosystem C increased asymptotically with age, but it was not affected by site quality. At rotation age (60 yr), ecosystem C in mined hardwood stands was less on high quality sites, but similar for low quality sites compared to non-mined hardwood stands. The overall results indicated that the higher the original forest site quality, the less likely C sequestration potential was restored, and the greater the disparity between pre- and post-mining C sequestration stocks.     

Drainage,Liming and Fertilization of Organic Soils. I. Long-term Effects on Acid/Base Relations

Abstract

Long-term changes of the acid/base relations of organic soils after drainage, fertilization and/or liming at three experimental sites—two ombrogenous and one soligenous—in south central Norway are discussed. These sites were drained, fertilized and/or limed in 1953–1956 and sampled in 1991–1992. Drainage at the ombrogelious sites caused: insignificant shifts of pH, higher bulk densities to 40 cm depth, higher ash percentage, higher contents of N and P to 20 cm depth and reduced concentrations of total Ca, K, Mg, Na, A1 and Fe in soil layers deeper than 20 cm. The soligenous site was not effectively drained; despite this, pH dropped about 0.5 unit in the surface and subsurface soil layers of the control plots, while small changes were measured for most other soil variables. The suggested reason for the pH drop is limited sulphide oxidation in the upper 20 cm drained layer. Base saturation at actual soil pH, when all treatments were included, was estimated with good precision by four regressors: pH, extractable Al, extractable Fe and extractable Ca (R²=0.90–0.95). Similar models explained 97–99”” of the variation in base saturation at soil pH=7.0. The lime effects at the properly drained oligotrophic sites were proportional to applied doses; for pH to 40 cm, base saturation to 60 cm, and Ca concentration to 60 cm depth. At the less well-drained soligenous site, effects were limited to the upper 30 cm layer. Both drainage and liming caused higher cation exchange capacities and proper drainage seems to be a prerequisite for the liming effect. Estimated recovery of calcium to 60 cm depth was 64–79% at the ombrogenous sites and 42–46% at the soligenous site.     

Effects of a deep container on morpho-functional characteristics and root colonization in Quercus suber L. seedlings for reforestation in Mediterranean climate

In the last decades, reforestation and afforestation programs are being carried out mainly with containerized seedlings. Container design determines the morphological and physiological characteristics of seedlings. However, container characteristics are often the same for plant species with very different growth strategies. The most commonly used nursery containers are relatively shallow and limit tap root growth; consequently, species relying on the early development of a long tap root to escape drought, such as those of the Quercus genus, might need to be cultivated in deep containers. The aim of this paper was to compare the morphological and physiological characteristics of Quercus suber L. seedlings cultivated in shallow containers (CCS-18, depth 18 cm) with seedlings cultivated in deep containers (CCL-30, depth 30 cm). Both container types used were made of high-density polyethylene, cylindrical in shape, open-bottomed, with a diameter of 5 cm, two kinds of vertical ribs on the inside wall showing a cultivation density of 318 seedlings/m². At the end of nursery culture, the seedlings cultivated in the CCL-30 deep container presented a longer tap root, higher shoot and root biomass and higher Dickson Quality Index (DQI). Moreover, the CCL-30 seedlings showed a higher root growth capacity (RGC), they reached deep substrate layers faster and they presented higher root hydraulic conductance. These morpho-functional advantages improved the CCL-30 seedling water status, which was expressed by higher stomatal conductance during an imposed drought period.     

森林资源一类清查和二类调查数据的协调性问题探讨

针对森林资源一类清查和二类调查存在两套数据的问题,提出了通过产出一套综合数据以解决协调性问题的方案。并举例进行了说明。     

Long-term impacts of prescribed burning on regional extent and incidence of wildfires—Evidence from 50 years of active fire management in SW Australian forests

Prescribed burning is advocated for the sustainable management of fire-prone ecosystems for its capacity to reduce fuel loads and mitigate large high-intensity wildfires. However, there is a lack of comprehensive field evidence on which to base predictions of the benefits of prescribed burning for meeting either wildfire hazard reduction or conservation goals. Australian eucalypt forests are among the very few forest types in the world where prescribed burning has been practised long enough and at a large enough spatial scale to quantify its effect on the incidence and extent of unplanned fires. Nevertheless even for Australian forests evidence of the effectiveness of prescribed burning remains fragmented and largely unpublished in the scientific literature.     

闽江流域洪灾与森林生态环境的研究Ⅰ.闽江流域洪灾成因与森林的水文效应

通过收集大量闽江流域气象、地质、土壤、水文、水系、森林资源和人类活动等资料 ,揭示了闽江流域洪灾的成因 :自然条件 (即异常气候和蒲扇形水系等 )是直接原因 ,人类不合理的活动造成的水土流失 ,河床抬高 ,流域蓄洪能力下降 ,特别是森林资源质量的下降 ,引起的保土蓄水和阻洪滞洪功能的严重削弱 ,是根本原因。同时也分析了森林与水文的关系 ,揭示了森林在防灾减灾中的作用。     

海子坪天然毛竹林的现状及保护价值初探

海子坪是中国以保护天然毛竹林为主批准成立的省级自然保护区,是国内未经人为干扰破坏、保存最好、面积最大的唯一天然毛竹林。通过对海子坪自然保护区天然毛竹林的现状进行分析总结,指出海子坪天然毛竹林具有有利于竹类植物种质资源的保存;有利于毛竹种群的遗传改良;有利于天然毛竹林植物群落遗传多样性的研究;有利于为人工竹林的生态恢复指明方向和有利于填补竹类研究相关领域空白的五大保护价值。     

森林资源评价的发展及研究

从有关的概念入手，论述了不同林业时期的森林资源评价发展过程，进而从森林的三种效益方面综述了国内外森林资源评价研究的进展情况，并对国际性、国家性以及区域性的森林资源可持续发展的评价指标体系研究和森林资源的评价路线作了评述。据此，以思考的方式对今后的森林资源评价研究提出了意见。     

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。     

浅谈祥云县天然林保护工程区森林分类与经营意见

祥云县位于大理白族自治州东部,总面积2441．65hm^2,是全省三大老旱区之一,在分析祥云县森林资源现状以及林业生态环境评价的基础上,阐述了森林分类区划的结果为：生态保护区面积160698hm^2,占林业用地面积的96．0％。商品林经营区面积6480hm^2,占4％,并分别提出了目标和经营意见。     

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.     

The flexural properties of young Pinus elliottii x Pinus caribaea var. hondurensis timber from the Southern Cape and their prediction from acoustic measurements

The objectives of this study were to determine the bending strength and stiffness properties of young Pinus elliottii x P. caribaea var. hondurensis timber from the Southern Cape, South Africa, and to evaluate the predictability of these properties from acoustic measurements on standing trees, logs and their sawn boards. The timber has good bending strength (MOR) properties but the mean stiffness (MOE_stat) was significantly lower than that required for structural-grade timber. The mean MOE_stat was also about 30% lower than a P. radiata control sample. The MOE_stat of sawn boards could be predicted from acoustic stress wave measurements on standing trees with a correlation (r) of 0.48 and from acoustic resonance frequency measurements on sawn boards with a correlation of 0.85. The MOR of sawn boards was not significantly correlated with acoustic stress wave measurements on standing trees and only moderately correlated with acoustic resonance frequency measurements on sawn boards (r = 0.45).     

观景距离和光照条件对黄栌林景观色彩的影响

为分析观景距离和光照条件对景观色彩呈现的影响,以八达岭国家森林公园红叶岭黄栌森林景观为研究对象,通过利用在不同观景距离、光照条件下拍摄的照片,设计试验,定量提取并计算HSV色彩,进行显著性检验等。结果表明:1)观景距离对景观色彩影响的试验中,Friedman秩和检验色彩全分量P值均远大于显著性水平α=0.05,色彩分量占比差值的T检验均以P值小于α=0.05拒绝μ≥0.1的原假设,即观景距离对森林景观色彩无明显影响。2)光照条件对景观色彩影响的试验中,Friedman检验全分量统计量均小于χ_0.05~2(12-1)=4.575,色相分量占比差值以92%的比例拒绝T检验的原假设μ≥0.1,彩度分量和明度分量分别以33%和27%的比例接受原假设μ≥0.1,即光照条件对景观色彩的色相分量无明显影响,对彩度和明度分量影响较大。3)本研究提出了使用色彩占比差值实施T检验的方法,对森林景观呈现进行定量分析,否定了观景距离、光照条件等客观因素对森林景观色彩呈现有较大影响的感性观点,为景观美学进一步研究提供了理论依据。     

施肥对毛白杨生长量、叶片氮(N)、磷(P)、钾(K)含量及蒸腾作用、气孔阻力影响的研究

对二年生三倍体毛白杨进行了施肥试验,分析了不同施肥水平、不同生长月份以及不同无性系对胸径、树高生长量和叶片N、P、K含量的影响,及其在生长季的变化规律,蒸腾作用和气孔阻力的不同生长月份和日变化情况。结果表明,不同施肥水平和生长月份对生长量和叶片N、P的含量有极显著影响;不同的无性系对K的含量有极显著的影响;在生长季毛白杨生长量与叶片N、P、K含量的变化规律相吻合;不同生长月份以及一天内不同时间,蒸腾速率和气孔阻力均存在极显著差异;蒸腾速率和气孔阻力日进程呈单峰曲线,高峰出现在中午。     

云南松林分与小蠹虫的竞争状态研究

云南松林遭小蠹虫危害以后,常由于林分抵御功能的不同而形成区域性的蠢害林分系统,即在"虫群区域"内存在着"衰退"和"发展"两种林分演变过程,若按"演变属性"来分析,则看到蓄积量下降、蓄积量停滞、蓄积量上升等3种林分演变过程是蠹害林分系统的普遍性特征,前2种属于"衰退状态",后1种属于"发展状态"。对3个蠢害林分系统的"演变属性"用二项分布P(衰退概率)+Q(发展概率)=1来描述,那么二项式(P+Q)3方程中的系数1、3、3、1成为系统中不同"演变属性"的概率论判断。由人为因素、虫群因素、环境因素引起的林分"衰退"和"发展"当然是随机的,但从分析中看到人的正、反两面行为都会引起林分与虫群相互作用的变化。     

枇杷疏花疏果技术及对产量品质影响研究

通过对各参试品种在湘南低山丘陵区红壤土、石灰土、钙质土立地条件下枇杷优质丰产高效栽培技术研究及相关资料的系统分析,提出了枇杷疏花疏果技术要点。并以红壤土上10~14年生太城四号枇杷为材料,系统研究了疏花疏果对枇杷果实产量及品质的影响。结果表明:太城四号枇杷疏花疏果后以每穗留果3~5个为最佳,疏果后平均单果重、单株产量及收益分别比对照提高117%、32%、163%。同时可提高果实的可食率、可溶性固形物含量、含糖量,降低含酸量,有效改善果实品质、口感风味、色泽,大大缩短果实采摘期。     

花桥板栗嫁接苗新梢径与长生长相关性研究

以花桥板栗嫁接苗为研究对象,通过调查嫁接苗的新梢径、新梢长等,建立秋季腹接嫁接苗的新梢径与新梢长、春季切接嫁接苗的新梢径与新梢长的关系方程,并对秋季腹接和春季切接嫁接苗的新梢径、新梢长进行了比较。结果表明:秋季腹接嫁接苗的新梢径(x)与新梢长(y)的关系方程为y=43.838 ln(x)+75.439。春季切接嫁接苗的新梢径(x)与新梢长(y)的关系方程为y=45.869 ln(x)+83.612。秋季腹接和春季切接嫁接苗的新梢长无明显差异。     

沈阳地区藤本月季引种及栽培技术的研究

随着沈阳的城市化步伐的加快,高层建筑云集,公路四通八达,车辆也越来越多,污染情况越来越严重,人们对身边环境有了越来越多的期许,然而城市化的快速发展,沈阳园林绿化用地越来越紧张,因此垂直绿化是我们有效解决绿化用地不够的有效方式。藤本月季的生长习性能使我们在有限的空间环境里创造出更多的垂直园林绿地,藤本月季已在多个城市中得到应用,在耐旱、耐寒、抗病害、粗放的栽培养护管理方面也有了多方面的研究,经济效益可观。如若大批量的应用会给为社会带来更大的环境效益及社会效益。     

Effects of thinning and site productivity on culmination of stand growth: results from long-term monitoring experiments in Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don) forests in northeastern Japan

We analyzed data from 28 long-term experimental monitoring plots installed in Japanese cedar (Cryptomeria japonica D. Don) plantations in northeastern Japan to examine how site productivity and thinning practices relate to culmination in stand growth. Site productivity and thinning practices in the plots were evaluated by site index (dominant tree height at 40-years old) and by cumulative thinning rate (cumulative thinning volume divided by cumulative gross production during the entire period of measurement). Culmination of stand growth was evaluated by culmination age of the mean annual increment (MAI) and its maximum value (Max MAI). Max MAI for the mean annual gross increment (MAIgross) and mean annual net increment (MAInet) increased with increasing site index, but did not change with cumulative thinning rate. Culmination age for MAIgross decreased with increasing site index, but did not change with cumulative thinning rate. Culmination age for MAInet decreased with increasing site index. Additionally, culmination age for MAInet increased with increasing cumulative thinning rate in sites with a high site index (>19.3 m) but not in those with a low site index (<19.3 m). These results indicate that thinning extends the culmination age without changing Max MAInet under high site productivity. Therefore, thinning increases total net yield in sites with high productivity based on a long-term perspective.