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1.
土壤中汞的化学形态及其影响因素   总被引：11，自引：0，他引：11  
An investigation and on 13-year-old(1984-1996) Chinese fir and Tsoong‘s tree mixed forests in Jianou City,Fujian Province,China was carried out to compare the influences of different interplanting types of individual tree-tree,row-row,row-strip(three rows)and pure Chinese fir stands on soil properties.Compared with the pure stands of Chinese fir ,the mixed stands exerted a posivtive effect on soil fertility,with increases in soil organic matter,total N,available P and available K.Moreover,improvements were also observed in soil enzymatic activities ,aggregate structure,structure,stability,status of soil porosity,soil aeration and penetrability in miexd stands.The row-row interplanted stands had the best effect on tree growth and soil properties among these mixed forests.In the southern subtropical region,the spreading of the row-row mixing model of the two tree species would be helpful to preventin ghe soil from fertility deterioratio caused by successive plantation of Chineses fir.  相似文献   

2.
This paper deals with a study on the effects of Chinese fir,lobolly pine and deciduous oak forests o the nutrient status of soils in northern subtropics of China,adopting the principle of forest ecology in the case of similar climate and soil type.The experimental area was situated in the Xiashu Experimental Centre of Forest,where the soil is yellow-brown soil derved from siliceous slope wash.Sample plots of these 3 stands were established to study the nutrient status in litter ,the amount of nutrient uptake by roots,the quantity of nutrient output by percolating water outside the deep layer of soil,and the seasonal dynamics of available nutrient in surface soil.It was whown that the intensity of nutrient cycling in soil under deciduous oak was the highest,and the effect of oak in improving soil fertility was the best.The result of improving soil fertility by Chinese fir was the most inferior,though the intensity of nutrient cycling under that stand was higher than that under loblolly pine stand.The influence of loblolly pine on the improvement of soil fertility was better than that of Chinese fir,in spite of its lowest intensity of nutrient cycling.  相似文献   

3.
中国杉连作对土壤肥力的影响   总被引：10，自引：0，他引：10  
The changes in soil fertility under continuous plantation of Chinese fir were studied by comparing soil samples from different forest stands:the first and second plantations of Chinese fir,evergreen broad-leaved forests,and clear-cut and burnt Chinese fir land located at Xihou Village,Nanping of Fujian Province.The soils were humic red soil originated from weathered coarse granite of the Presinian system.Soil pH,CEC,base saturation ,exchangeable Ca^2 ,exchangeable Mg^2 and A1-P declined after continuous plantation of Chinese fir.The same trends were also found in the soils under broad-leaved stands and slash burnt lands.The explantation was that not merely the biological nature of the Chinese fir itself but the natural leaching of nutrients,soil erosion and nutrient losses due to clear cutting and slash burning of the preceduing plantation caused the soil deterioration .Only some of main soil nutrients decreased after continuous plantation of Chinese fir,depending on specific silvicultural system,which was different from the conclusions in some other reports which showed that all main nutrients,such as OM,total N,available P and available K decreased,Some neccessary step to make up for the lost base,to apply P fertilizer and to avoid buring on clear cut lands could be taken to prevent soil degradation and yield decline in the system of continuous plantation of Chinese fir.  相似文献   

4.
Vector analysis technique and ecological sequential comparison methods were adopted to study tree growth response to the micronutrients,B,Mo,Cu,Zn,Fe,and Mn,in soils derived from various parent materials in the forest area of Tailhu Lake region in southeast China,The results showed that the dry weight of individual current-year needle of Chinese fir(Cunninghamia lanceolata) grown on the soil derived from granite parent rock was increased by 8% and 13% in comparison with that grown on the soils derived from sandstone and ash-tuff parent rock,respectively.And such dry weight of loblolly pine (Pinus taeda) grown on the soil derived from sandstone parent rock was increased by 21% in comparison with that on the soil derived from ash-tuff parent rock.One of the reasons for those results was that micronutrients content in the soil derived from ash-tuff parent rock were not sufficient to meet the requirement of the growth of Chinese fir and loblolly pine ,i.e.,micronutrients in soil were deficient and/or induced defiient.The amounts of Cu,Zn,Fe,and Mn uptake by Chinses fir and loblolly pine were in agreement with the contents of available micronutrients in soil respectively,except for B and Mo.Meanwhile,there might exist and “antagonism“ between the uptake of B versus Mo by trees,although more studies are needed to confirm it .Regression analysis indicated that amount of a soil available micronutrient was correlated to the type of parent material and its total amount in the forest floor, except for B.The F test identified that the correlation of each equation reached the significant level to different extents,respectively,The t test confirmed that amount of available forms was mainly depended on the type of parent material for Mo,Cu,Zn and Mn but on the forest floor for ,Fe,There was a feedback effect of forest stand on the amount of soil available micronutrients.The ability of accumulating available micronutrients in soil was better by the sawtooth oak(Quercus acutissima) stand than by the Chinese fir stand (except for B).The ability of accumulating available Zn,Fe,Mn and Mo in soil was better by the Chinese fir stand than by the loblolly pine stand ,while as for available B and Cu,by the latter was better than by the former,When discussing the efect of forest stand on the amount of soil available micronutrients,not only the amount of micronutrient in the forest floor and the parent materials but also the amount of micronutrient taken up by current-year needles have to be considered.  相似文献   

5.
Conversion of natural forests into pure plantation forests is a common management practice in subtropical China. To evaluate the effects of forest conversion on soil fertility, microbe numbers and enzyme activities in topsoils (0-10 cm) were quantified in two 33-year-old monoculture plantations of Castanopsis kawakamii Hayata (CK) and Cunninghamia lanceolata Lamb. (Chinese fir) (CF), and compared to a neighboring relict natural C. kawakamii forest (NF), in Sanming, Fujian. Five soil samples were collected once each in January, April, July, September and November in 2000 in each forest for laboratory analysis. Over the sampling year, there were significant differences for bacteria, fungi and actinomycetes between forests and between seasons (P < 0.05). The largest bacteria and fungi populations were in NF, while CF contained the greatest number of actinomycetes. There were also significant differences (P < 0.05) with microbial respiration for forests and seasons. Additionally, compared with NF, urease and acid phosphatase were significantly lower (P < 0.05) in CK and CF. Also, the correlations of soil hydrolysable N and available P to soil microbial and enzymatic activities were highly significant (P < 0.01). Thus, to alter the traditional Chinese fir monoculture so as to mimic the natural forest conditions, managing mixed stands of Chinese fir and broadleaf trees or conducting crop rotation of conifers and broadleaf trees as well as minimizing forest disturbances like clear-cutting, slash burning and soil preparing, could be utilized.  相似文献   

6.
Soil properties were investigated in sites where three succeeding generations of Chinese fir (Cunninghamia lanceolata (Lambert) Hooker) in Nanping, Fujian, China, were cultivated in order to show the impact of a repeated monoculture on site productivity. Compared with the first generation (FG) stand the soil structure deteriorated in the second generation (SG) and the third generation (TG) stands. For instance, the destruction rate of the peds increased by 55%-115% in the SG and the TG stands compared to the FG stand. Soil nutrient storage and nutrient availability also decreased in the SG and the TG stands. For surface soils of 0-20 cm, the organic matter content, total N and P, and available N and P decreased by 3%-20% relative to those in the FG stand. For many soil parameters, the differences between the FG stand and the SG and the TG stands were statistically significant (LSD test, P < 0.05). Furthermore, with each succeeding generation of Chinese fir, the total number of soil microbes declined, the soil enzyme activity weakened, and the soil biological activity decreased. In order to maintain sustainable site productivity, new silvicultural practices need to be developed for management of Chinese fir plantations.  相似文献   

7.
中国亚热带地区冷杉和砂仁 农林系统的土壤肥力研究   总被引：4，自引：0，他引：4  
A trial of interplanting and non-interplanting villous amomum(Amomum villosum Lour.) under the canopy of Chinese fir(Cunninghamia lanceolata Hook.)at age 22 was established in Sanming,Fujian of China,and a survey on soil fertility was carried out 10 years after its establishment .Compared with the control(non-interplanting), the properties of soil humus in agroforestry system were ameliorated,with a higher level of humification and resynthesis of organic detritus .The soil microbial population and enzymatic actvities were both higher under the influence of villous amomum.Both the nutrient supplying and nutrient conserving capacities of the soil were improved,This agroforestry system exhibited an advantage of improved soil fertility,as well as an accelerated rowth of Chinese fir ,it was therefore a sustainable management system suited for Chinese fir in South China.  相似文献   

8.
The effects of fertilization on the distributions of organic carbon (OC) and nitrogen (N) in soil aggregates and whether these effects vary with cropping system have not been well addressed.Such information is important for understanding the sequestration of OC and N in agricultural soils.In this study,the distributions of OC and N associated with soil aggregates were analyzed in different fertilization treatments in a continuous winter wheat cropping system and a legume-grain rotation system in a 27-year field experiment,to understand the effects of long-term fertilization on the distributions of OC and N in aggregates and to examine the recovery of soil OC and N in a highland agroecosystem.Manure fertilizer significantly decreased soil bulk density but increased the amount of coarse fractions and their associated OC and N stocks in the soils of both systems.Fertilizers N + phosphorus (P) and manure had similar effects on total soil OC and N stocks in both systems,but had larger effects on the OC and N stocks in ＞ 2 mm aggregates in the legume-grain rotation system than in the continuous winter wheat system.The application of P increased the OC and N stocks in ＞ 2 mm aggregates and decreased the loss of N from chemical fertilizers in the legume-grain rotation system.The results from this study suggested that P fertilizer should be applied for legume-included cropping systems and that manure with or without chemical fertilizers should be applied for semiarid cropping systems in order to enhance OC and N accumulation in soils.  相似文献   

9.
Alfalfa cropping has been considered an efficient method of increasing soil fertility.Usually nitrogen increase in root nodules is considered to be the major beneficial effect.A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil,initially containing illite and chlorite,in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping,soil potassium (K) content and soil clay minerals.The results indicated that soil K significantly accumulated after cropping,with a peak value at about 15 years,and decreased afterwards.The accumulated K was associated with the K increase in the well-crystallized illite,which was not extracted by the traditional laboratory K extraction methods in assessing bioavailability.The steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in the alfalfa soil.Plant biomass productivity peaked at near 9 years of culture,whereas soil K and clay minerals continued to increase until cropping for 15 years.This suggested that K increased in the topsoil came from the deep root zone.Thus alfalfa continued to store K in clays even after peak production occurred.Nitrogen did not follow these trends,showing a general decline compared with the native prairie soils that had not been cropped.Therefore,the traditional alfalfa cropping can increase K content in the topsoil.  相似文献   

10.
不同肥力水平和利用历史的红壤磷脂脂肪酸图谱   总被引：4，自引：0，他引：4  
Analysis of phospholipid fatty acids(PLFAs) was used to estimate the microbial community structures of eight Chinese red soils with different fertility levels and land use histories.The total amounts of PLFAs in the soils were significantly correltaed with soil organic carbon, total nitrogen,microbial biomass C and basal respiration,indicating that total PLFA was closely related to fertility and sustainbility in these highly weathered soils.Soils of the eroded wastelan were rich in Gram-positive species .When the eroded soils were planted with citrus trees,the soil microbial population had changed little in 4 years but took up to 8-12 yearss before it reached a significantly different population,Multivariate analysis of PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure.Howver,the difference of soil microbial community structure in the paddy field compared to other land uses was not larger than expected in this experiment.  相似文献   

11.
肉桂林取代杉木林后土壤肥力变化的研究   总被引：1，自引：1，他引：1  
对４年生肉桂林和杉木萌芽林的土壤肥力进行对比研究。结果表明：肉桂林的土壤结构、水分状况、孔隙组成和渗透性能均比杉木萌芽林好,土壤有机质、全Ｎ、全Ｐ、全Ｋ和速效养分含量也比杉林萌芽森有所增加。说明肉桂林取代杉木林后,林地土壤肥力得到较明显的改善。  相似文献   

12.
Abstract. After clear-felling of a first generation Chinese fir ( Cunninghamia lanceolata ) forest, mixed stands of Chinese fir and Michelia macclurei (a broadleaf tree) (MCM), pure M. macclurei stands (PMS) and pure Chinese fir stands (PCS) were established in 1983. The effects on soil were evaluated 20 years after planting by measuring physicochemical, microbiological and biochemical parameters. Both broadleaf monoculture and mixtures of broadleaf and conifer exerted a favourable effect on soil fertility. A soil quality index (SQI) decreased in the order: PMS (0.62) > MCM (0.57) > PCS (0.41). Improvement in soil quality, enhanced biological activity and forest productivity demonstrated that mixed stands are an effective measure to maintain sustainable forest productivity, as well as to control soil degradation under successive stands of Chinese fir. In addition, since the microbiological and biochemical parameters measured were sensitive to the forest management, they may be potential indicators for assessing the sustainability of different management systems. The results also showed that total organic carbon, cation exchange capacity and microbial biomass carbon are effective indicators of the improvement or deterioration of soil quality under forest.  相似文献   

13.
杉木与阔叶树叶凋落物混合分解对土壤性质的影响   总被引：13，自引：1，他引：13  
通过盆钵模拟试验对杉木与楠木、杉木与木荷叶凋落物混合分解后土壤性质进行研究,结果表明:土壤微生物区系中,细菌占微生物总数的98.18%~99.80%,真菌、放线菌在微生物总量中的比例差异不显著(P>0.05),分别为0.12%~1.01%和0.12%~1.08%;7月份土壤微生物中放线菌数量显著高于3月份土壤微生物中放线菌数量(P<0.05),而细菌数量相对较少;杉木、楠木以及木荷叶凋落物三者单独分解时,阔叶树林地细菌数量较大,杉木林地的真菌、放线菌数量较多。当杉木与楠木叶凋落物混合分解时,土壤三大微生物数量以及微生物总量都明显增加;与木荷叶凋落物混合分解时,仅细菌和微生物总量有所增加。混合分解后,林内土壤养分大体呈低~高~低的变化模式;pH值均有不同程度的,其中增加最多的是杉楠X1+3X2的处理。  相似文献   

14.
结合森林资源二类调查，以立地因子为依据，运用数量化回归方法，建立一系列方程，对广西林朵林场的林地进行杉木立地类型的划分和立地质量评价研究．结果表明：海拔、坡向、坡位和土层厚度是影响杉木生长的主导因子。所建立的方程具有较高的评价精度，可根据具体情况及对精度要求，选用适当方程．  相似文献   

15.
华蓥市山区典型林分水源涵养功能评价   总被引：2，自引：1，他引：1  
为研究南方丘陵山区典型人工林的生长现状和涵养水源能力,选取华蓥市6种林分作为研究对象,通过测定林下枯落物层和土壤层特征,分析比较不同林地枯落物和土壤的持水能力,对林地水源涵养能力进行评价。结果表明:杉木纯林(近自然经营)枯落物现存蓄积量最大,枯落物持水能力排序为杉木纯林(近自然经营)杉木纯林马尾松—檵木混交林(近自然经营)杉木—响叶杨混交林柏木纯林马尾松—杉木混交林;杉木纯林的土壤层总孔隙度、毛管孔隙度、有效持水量均为最优,分别达到67.67%,60.39%,138.11 t/hm~2;6种林地土壤有效持水量大小顺序为杉木纯林杉木纯林(近自然经营)马尾松—杉木混交林杉木—响叶杨混交林柏木纯林马尾松—檵木混交林(近自然经营);综合枯落物层和土壤层持水能力可知,杉木纯林(近自然经营)的水源涵养能力最强,为309.77 t/hm~2,马尾松—杉木混交林最弱。  相似文献   

16.
杉木人工林和阔叶杂木林土壤养分平衡因素差异的初步研究   总被引：22，自引：1，他引：22  
李昌华 《土壤学报》1981,18(3):255-261
杉木(Cunninghamia lancelata)是我国南方重要造林树种,人工林分布面积很大。在多年的林业实践中,发现杉木人工林,特别是速生的林分在连续栽植之后,一代不如一代,地力逐渐衰退。因此,连栽二、三代之后,就使其轮荒恢复杂木林。而阔叶杂木林则有恢复土壤肥力的作用,因而杉木一般以在常绿阔叶林或阔叶杂木林砍伐后第一次植杉的土壤上生长为最好[1]1)。  相似文献   

17.
吉林省东部低山丘陵区4种林分类型林地的土壤肥力分析   总被引：5，自引：2，他引：5  
根据吉林省东部低山丘陵区汪清林业局金仓林场中4种主要林分类型(长白落叶松天然林、长白落叶松人工林、天然针阔混交林和天然阔叶混交林)的土壤肥力调查数据,分析和比较了4种林分类型林地的土壤物理和化学性质,并采用主成分分析评价了其土壤肥力状况。(1)随土壤深度增加,土壤容重和土壤pH值增大,而土壤含水量、阳离子交换量和养分含量减少,但其在不同林分下的变化程度不同;(2)林分类型对部分土壤化学性质(如土壤CEC、有机质、全氮和速效钾)影响显著。其中,天然针阔混交林的土壤含水量、土壤pH值、阳离子交换量、有机质含量及全氮、磷、钾含量均为最高;(3)采用主成分分析法对不同林分类型的林地土壤肥力状况进行了评价,结果发现土壤肥力状况为:天然针阔混交林>长白落叶松天然林>长白落叶松人工林>天然阔叶混交林。建议在经营现有的林分时,考虑近自然育林,及时进行林下补植更新,并营造针阔混交林,以改善该区林地土壤的肥力状况。  相似文献   

18.
Mineralization of soil organic carbon (C) plays a key role in supplying nutrient elements essential to plant growth. Changes of C mineralization of mixed stands of Chinese fir and Michelia macclurei (a broadleaf tree), pure M. macclurei stands, and pure Chinese fir (Cunninghamia lanceolata) stands established in 1983 after clear‐felling of a first‐generation Chinese fir forest were analyzed in Huitong, Hunan Province, China, and compared with those of a stand of native secondary evergreen broadleaf forest (NBF). The results showed that NBF soil had the greatest C mineralization. Mixture of Chinese fir and M. macclurei had no effect on total soil organic C in comparison with pure Chinese fir plantation, but significantly increased C mineralization from soils was detected in this study. This positive influence on C mineralization could be explained by the increase of soil labile C pools and soil microbial biomass and activity. From the analysis of C mineralization, soil microbial properties, and labile organic C, mixtures of broadleaf and Chinese fir can be considered to be an effective sustainable management model for a Chinese fir plantation. Given strong correlations with microbiological and biochemical characteristics of soils and an easier process of determination, hot water extraction, hot water–extractable C (HWC) could be used as an integrated measure of forest soil quality in mid‐subtropics.  相似文献   

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