雨强和土地利用方式对黄土丘陵区水土流失的影响

为了更好掌握黄土丘陵区雨强和土地利用方式对水土流失的影响规律和机理,利用人工降雨模拟器,设计了5种雨强和4种土地利用方式的区组试验,对水土流失进行了定量研究。结果表明：雨强对不同土地利用方式的产流产沙都呈极显著的正效应,4种土地利用方式的地表平均产流产沙与雨强均呈幂函数显著增长趋势;5种雨强的平均地表产流量为林地＞休闲耕地＞栽培草地＞草地,平均产沙量分别为休闲耕地＞栽培草地＞草地＞林地,产流与产沙没有呈现完全的对应关系。如果没有林冠层、灌木层和枯枝落叶层对降雨的截留、阻滞和消弱,林地产流量高于其他土地利用方式,但具有良好的保土效果,而草地具有良好的保水和保土效果。     

Sewage sludge as a fertilizer of pole stage forests: short-term hydrochemical fluxes and foliar response

Abstract. Proposed restrictions on the disposal of sewage to the marine environment means that alternative land based outlets are required in the UK. Commercial forestry represents a significant land use that could receive and benefit from the application of sewage sludge, to overcome the generally poor soil nutrient status. The oligotrophic and sensitive nature of surface waters in many afforested areas requires that the environmental consequences of the widespread use of organic fertilizers in forestry are carefully considered. This paper compares the effects of an N and P fertilizer with that of sewage sludge on the nutrient content of foliage in a pole stage Scots pine ( Pinus sylvestris ) forest and of nutrient fluxes in soil. Both conventional fertilizer and sewage treatments had significant but differing effects on the availability and leaching of the major nutrients, especially N and P. Evidence for increased nitrification and nitrate production with time was apparent for both treatments. Fluxes of N and P in mineral horizon leachate were consistently smaller than those from the overlying organic horizon. Foliar nutrient concentrations after one year were significantly higher ( P < 0.01) in all of the treatments, and conventional fertilization with urea produced a significantly higher foliar N concentration than that measured in the sludge-treated plots. There was no evidence for appreciable N or P leaching from the site within a year of sludge application.     

Soil compaction under timber harvesting machinery: a preliminary report on the role of brash mats in its prevention

Abstract. Forest soil sustainability and future crop productivity is at risk if mechanised harvesting operations cause soil damage. In UK upland forestry, soil protection is usually provided by placing harvesting residues (brash) over areas where machinery traffic is required. In this study, various thicknesses of brash mat were tested for their ability to reduce compaction of a surface water gley soil at Kielder Forest, Northumberland. Changes in penetration resistance and dry soil bulk density were studied after passes by forest harvesting and timber extraction machinery running on the brash. The study shows that normal harvesting operations caused some soil compaction. However, the brash mat system was shown as important in protecting the soil. Soil under brash mats experienced some compaction to at least 45 cm depth. The thickest brash mat, composed of residues from 10 rows of trees, was unable to prevent compaction completely. Nevertheless, the protective role of the brash mat system was clearly confirmed when compared to timber extraction over bare soil. The point at which compaction has a detrimental effect on the establishment and stability of future tree rotations remains uncertain.     

固原县抗旱造林技术措施试验研究

作者通过对固原县东部黄土丘陵区抗旱造林技术措施的试验研究,初步总结出以下抗旱造林技术措施:1.选择抗旱树种;2.提前整地;3.地膜造林;4.截干造林;5.浸水蘸浆;6.保根保湿;7.秋季造林等,从而为宁南干旱、半干旱黄土丘陵区提高造林成活率提供了科学依据。     

Experimental evidence for the interacting effects of forest edge,moisture and soil macrofauna on leaf litter decomposition

Forest ecosystems have been widely fragmented by human land use. Fragmentation induces significant microclimatic and biological differences at the forest edge relative to the forest interior. Increased exposure to solar radiation and wind at forest edges reduces soil moisture, which in turn affects leaf litter decomposition. We investigate the effect of forest fragmentation, soil moisture, soil macrofauna and litter quality on leaf litter decomposition to test the hypothesis that decomposition will be slower at a forest edge relative to the interior and that this effect is driven by lower soil moisture at the forest edge. Experimental plots were established at Wytham Woods, UK, and an experimental watering treatment was applied in plots at the forest edge and interior. Decomposition rate was measured using litter bags of two different mesh sizes, to include or exclude invertebrate macrofauna, and containing leaf litter of two tree species: easily decomposing ash (Fraxinus excelsior L.) and recalcitrant oak (Quercus robur L.). The decomposition rate was moisture-limited at both sites. However, the soil was moister and decomposition for both species was faster in the forest interior than at the edge. The presence of macrofauna accelerated the decomposition rate regardless of moisture conditions, and was particularly important in the decomposition of the recalcitrant oak. However, there was no effect of the watering treatment on macrofauna species richness and abundance. This study demonstrates the effect of forest fragmentation on an important ecosystem process, providing new insights into the interacting effects of moisture conditions, litter quality, forest edge and soil macrofauna.     

森林植被垂直截留作用与水土保持

本文分析了林冠层、灌木草本层、枯枝落叶层的截留量及其削减的降雨能量,并以六盘山林区各森林流域为例。评论了垂直截留作用对林地土壤和森林流域水量收入的影响,阐明了森林植被垂直结构中各层次在保持水土中的地位。     

Aluminum complexation suppresses citrate uptake by acid forest soil microorganisms

Organo-mineral interactions have been hypothesized to play a major role in biogeochemical cycling and pedogenesis in some forest soils. These processes are likely to be controlled to some extent by their persistence in soil, however, the factors regulating their bioavailability remain poorly understood. Therefore, we investigated the microbial utilization of ¹⁴C-labeled citrate in glass bead filled bioreactors containing a biofilm developed from an inoculum from an acid forest soil. The removal of Al-citrate in the bioreactors was negligible compared to the rate of citrate removal in the absence of Al. There was no evidence that in the short-term the microbial community adapted to increase the utilization of Al-citrate. In bioreactors filled with a Picea abies forest soil (Haplic Arenosol) the rates of citrate utilization were always slightly higher than that of Al-citrate. We conclude that complexation of citrate by metals such as Al may have a significant effect on their role in soil biogeochemical cycles.     

Changes in forest floor and mineral soil carbon and nitrogen stocks in a boreal forest after clear‐cutting and mechanical site preparation

Significant amounts of organic carbon (C) and nitrogen (N) are accumulated in soil in boreal forests. However, increased concern has been shown regarding the negative impacts of forestry operations on both the C sequestration and N stocks in soil. Changes in the C and N stocks in woody debris, forest floor and mineral soil (0–20 cm) were studied in Eastern Finland for 10 years after stem‐only clear‐cutting followed by soil harrowing. Samples were taken from the uncut forest and from the different microsites formed by the harrowing (ridges, furrows and undisturbed areas). Carbon and N from logging residues were not incorporated into the forest floor or mineral soil stocks to any great extent. After 5 years the C stock above the mineral soil was smaller (< 20%) in the treated area than in the uncut forest and after 10 years it was < 50% smaller. The corresponding N stock was marginally larger (< 5%) after 5 years, but smaller (< 20%) after 10 years. In the mineral soil there were no changes; only the furrows lost C and N when compared with the other microsites, but not when compared with the forest. Harrowing increased the spatial variation in the forest floor C and N stocks. The comparison of the N losses from the soil and logging residues and woody debris with the leaching losses, the amounts utilized by the regenerating vegetation or estimated to be immobilized by the stumps at the same site indicated that N which remained after the clear‐cutting was retained at the site. For a full understanding of the impact of such a disturbance on stocks at a site all significant fluxes and stocks would need to be monitored.     

重庆市四面山林地土壤水分入渗特性研究与评价

采用Spearman秩相关分析法与灰色关联度分析方法,对四面山几种不同林地土壤水分入渗特性进行了研究分析。结果表明,林地土壤容重、砂砾含量及非毛管孔隙度对土壤饱和导水率具有显著相关性。非毛管孔隙度、砂砾含量与土壤饱和导水率成正相关关系,土壤容重与土壤饱和导水率成负相关关系。选取土壤水分初渗速率、稳渗速率、入渗时间与累积入渗量4项参数进行灰关联评价。林地土壤水分入渗特性灰关联紧密相关程度依次为阔叶林(0.8031)>楠竹林(0.7869)>针阔混交林(0.4454)>针叶林(0.4039),阔叶林土壤在所研究的几种林地中具有较好的渗透性能。Horton水分渗透模型对各林地土壤水分入渗过程拟合的相关系数R值均大于0.950,对所研究的四面山林地土壤水分入渗过程具有良好的适用性。     

刺萼龙葵入侵对不同类型土壤特性的影响

外来入侵植物对土壤生态系统的影响已成为入侵生态学研究的热点。本文选取河北宣化和吉林白城2个刺萼龙葵(Solanum rostratum Dunal.)入侵典型地区,研究刺萼龙葵入侵对不同类型土壤养分及酶活性的影响。每个地区分别选择4个生境作为样地,宣化地区生境包括荒地、路边、农田和林地,白城地区生境包括荒地、路边、农田和草原,其中宣化的林地和白城的草原为每个地区特有的生境。采用滴定法和比色法测定土壤养分和酶活性。结果表明,与未入侵样地(CK)相比,刺萼龙葵入侵显著提高了农田、林地和草原的土壤全氮含量(P0.05),其中宣化(灌淤土)农田和林地全氮含量比CK增加102.49%、79.02%,白城(淡黑钙土)农田和草原比CK增加44.04%、21.81%;刺萼龙葵入侵显著提高了农田和林地的土壤铵态氮含量(P0.05),其中宣化农田、林地中土壤铵态氮含量比CK增加137.59%、50.32%,白城农田中增加140.18%;刺萼龙葵入侵也提高了路边、林地、农田(白城)和荒地(宣化)的土壤硝态氮含量(P0.05),其中,宣化荒地、路边和林地土壤硝态氮含量较CK增加65.52%、32.96%和22.68%,白城路边和农田分别增加132.59%、153.96%。刺萼龙葵入侵显著提高了宣化地区及白城荒地和农田的土壤有机质含量(P0.05);降低了宣化荒地、农田和林地的土壤全磷含量(P0.05),土壤全磷分别比CK降低54.63%、70.81%和29.68%,白城路边和草原的土壤全磷含量分别较CK下降17.40%、14.69%(P0.05);刺萼龙葵入侵对2个地区土壤全钾和速效钾则无显著影响。刺萼龙葵入侵显著提高了荒地、农田、林地、草原和路边(宣化)的土壤脲酶活性(P0.05);宣化路边和白城荒地、草原的中性磷酸酶的活性,宣化荒地和林地土壤过氧化氢酶活性均显著提高(P0.05),对白城过氧化氢酶则无显著影响。刺萼龙葵入侵对某些生境的土壤养分和酶活性无显著影响可能与入侵生境的小气候、入侵时间长短等因素相关,需进一步深入研究。总之,刺萼龙葵入侵改变了2个地区土壤理化性质和酶活性,其可能通过改变土壤养分及土壤酶活性,以创造对自身有利的土壤环境,从而进一步扩散蔓延。     

红壤地区杉木人工林土壤肥力质量性状的演变

通过在江西省红壤地区主要林区的铜鼓县和德兴县选择不同林龄（1～28年）的杉木人工林样地采用随机网格法对土壤分层取样，并对土壤样品进行分析后的研究结果表明，从造林阶段到5～8年的幼林期，包括林地凋落物层、土层厚度、有机质、全N、CEC、BS、pH和速效N、P、K在内的林地主要土壤质量性状大幅度退化。随着树龄的增大，林地土壤质量性状开始缓慢恢复。但是，即使杉木人工林进入了主伐期，土壤质量性状的恢复程度仍选低于其初始水平。     

鲁中山区不同人工林土壤水分特征

 为了解不同林分土壤水资源的变化规律,为北方石质山区植被恢复重建提供科学依据,在济南市南部山区圣泉寺林场内,以5种人工林分为研究对象,对其土壤物理结构和土壤水分特征进行了研究。结果表明:1)各种林分类型的土壤容重、孔隙度和渗透速率等表征土壤水文物理性质的指标,明显好于无林地,其中混交林好于纯林,刺楸纯林好于黄连木、栾树纯林。2)在旱季和雨季,随着土壤深度的增加,大部分林分土壤含水量呈现递减趋势,其变动幅度小于无林地。3)随着土壤深度的增加,各森林类型土壤饱和持水量逐渐减小;混交林表层土壤蓄水功能最好,其他林分各层次差异较小;在涵养水源和水分有效性方面,混交林优于纯林,纯林中以刺楸较好,栾树较差。在今后的森林经营中,首先考虑营造混交林分,树种组成以刺楸+黄连木较好,若营造纯林,应选择营造刺楸林分。     

森林生态水文功能与林业发展决策

 从森林的作用层面和生态水文过程的角度总结分析了森林的水文调节、土壤保持和削减洪峰等生态服务功能,并讨论了当前国内外学术界共同关心的增加森林植被会减少径流的问题,认为应综合地评价造林活动和森林植被恢复的影响,但同时应加强森林生态水文基础性研究,强化林业发展和森林管理决策的科技基础,以提高森林植被建设和水资源管理及林业发展综合决策的能力。     

The effect of Amazonian Eucalyptus plantations on soil aggregates and organic matter density fractions

Afforestation with Eucalyptus species is increasing in Brazil, but there is little information on the impacts of intensively managed short-rotation forestry on soil aggregate dynamics and labile organic matter fractions in these tropical ecosystems. This study investigated soil aggregate dynamics in a clay and sandy soil, each with a Eucalyptus plantation and an adjacent primary forest. It is shown that silviculture alters the processes of soil aggregate formation on both soil types. Micro-aggregates at 0–20 cm depth in the planted clay soil were 40% greater in mass than under native forest, and C and N were reduced by 87 and 75%, respectively. In plantations with a sandy soil, micro-aggregates had equal mass compared with native forest, but increased in C and N by 20 and 67%, respectively. The results from the sandy soil indicate that C and N increased in micro-aggregates following afforestation. Macro-organic matter fractions separated by density had lower mass, C, and N concentrations, and higher C:N ratios only in lower soil profiles, with native forest having greater values in all comparisons with light and medium fractions. The differences in micro-aggregate C and N and in the light and medium macro-organic matter fractions between the upper and lower soil profiles in both soils, indicate that silvicultural management had contrasting effects on different soil textures and at different depths. Increased micro-aggregate protection of C and N in the sandy plantation soil could negatively affect long-term nutrient cycling although the quantity and quality of light and medium macro-organic matter fractions did not change between plantation and native forest in the upper soil profile; this indicates that labile OM availability and quality had not been diminished in plantation soils at this depth.     

4种不同植被群落类型表土的抗蚀力学特性

[目的]研究黄土高原农林业生产表层土壤水土流失,为该区域及其相似地区生态修复中树种选择及配置提供科学依据。[方法]以杨树+柠条乔灌混交林、杨树纯林、油松常绿针叶林和柠条灌木纯林下4种不同植被群落类型下表土为对象,进行抗剪力学特性研究,并分析土壤含水率对其力学特性的影响力。[结果]在测试表土含水率2.5%～12.5%范围内,4种不同植被类型及裸地对照样地土壤结皮抗剪强度和黏聚力均随着土壤含水率的增加呈增大的趋势,表明在一定范围内表土湿润程度的增加对提高土壤表层抗蚀能力起到积极作用;4种不同植被群落类型表土抗剪强度和黏聚力的值均显著大于裸地的值,说明水土保持的林草措施对表层土壤结构的改善起到了促进作用,从而提高了表层土壤的抗侵蚀能力;在测试含水率2.5%～12.5%范围内随着含水率的增加各样地表土内摩擦角无明显的变化规律。[结论] 4种不同植被群落类型中柠条+杨树混交林下表土抗剪强度、黏聚力总体表现最大,这也从另外一方面说明了水土保持的林草措施中营造混交林的优越性。     

小浪底库区坡地不同利用方式下土壤养分的流失特征研究

通过野外模拟降雨试验,分析了撂荒荒坡、林草间作、农林间作、造林林地和坡耕地翻耕种植玉米、坡耕地翻耕休闲6种利用方式下的土壤流失特征。研究结果表明:(1)坡耕地及农林间作下地表径流中的有效钾和硝态氮含量高于撂荒荒坡、林草间作和造林林地。(2)撂荒荒坡、林草间作和造林林地沉淀泥沙中的全氮、全磷、全钾和有机质含量高于其它3种利用方式。(3)径流液养分和沉淀泥沙养分含量产流初期达到高值,之后趋于稳定。(4)不同形态的养分在泥沙中有富集现象;富集比在1.01~1.43之间,不同利用方式下富集比差异不大。     

利用数字土壤制图技术评价森林立地质量

[目的]为了提升森林立地质量评价的精准性,探讨利用数字土壤制图技术对森林立地质量进行评价,助力精准林业的发展.[方法]以济源南山林场为研究区,以地形因子为预测因子,运用模糊C均值聚类方法(FCM算法)对立地评价所需的主要土壤属性进行预测制图,并在利用遥感影像数据获取林地其他立地环境因子分布图的基础上,应用灰色关联度法对...     

Forestry and soil erosion in Britain – a review

Abstract. Research on soil erosion under forest in Britain is reviewed. Erosion can increase as a result of afforestation in the uplands, sometimes with undesirable consequences for surface water quality. Published rates of erosion are usually close to 'natural' ones, at around 500 kg ha⁻¹ yr⁻¹. Of the forest operations that can lead to erosion ploughing is the most important. Clearfelling may also increase erosion, but little is known of its long-term effects. New developments in forestry may do much to reduce the risk of soil erosion, particularly the replacement of ploughing by subsoiling and the control of drain gradients.     

滇东南石漠化山地不同植被恢复模式下土壤地力变化和水土流失状况研究

通过对滇东南石漠化山地不同植被恢复模式下土壤的理化性质进行定点观测和地力变化及水土流失状况的分析,结果表明:封山育林地土壤的肥力较佳,其次是耕地土壤,这是由于封山育林地土壤多年来进行封山育林,耕地土壤进行了平衡施肥;3年后人工林地土壤的理化性质有很大改善,土壤肥力有很大提高,这是退耕还林的结果;从水土流失状况来看,耕地是产流产沙、固体和液体养分流失最严重的类型,人工林地水土流失最低,说明退耕还林和封山育林有利于石漠化山地土壤肥力的改善和水土保持功能的提高。     

黄土区刺槐和油松水土保持林合理密度的研究

 以黄土区刺槐和油松水土保持林为研究对象,在对水分循环要素进行长期监测的基础上,以水分亏缺量为依据,利用径流林业的基本原理,结合林分调查结果,提出了利用胸径计算刺槐和油松林合理密度的公式。利用该密度参考值管理刺槐和油松水土保持林,可以保证林木正常生长所需水量,不会造成林地土壤干化。同时以刺槐和油松林地的土壤水分含量、最低含水量和难效水频率为指标,提出了黄土区适宜的刺槐和油松水土保持林的管理密度。