外文翻译挖掘机开垦森林土壤与修正方案

1、附录Reclamation of forest soils with excavator tillage and organic amendments AbstractIn early 1994, a research project was initiated to evaluate the success of several techniques aimed at restoring productivity to degraded soils on landings near Vama Vama Creek, 44 km east of Prince George in Central

2、 British Columbia. Soils were developed from morainal parent materials, the usual surface soil texture was silt loam. Two organic amendments were used in this study, including freshly prepared wood chips and old sawdust. An excavator equipped with a site preparation rake was used to till the soils t

3、o a depth of 0.50 m. Organic amendments were subsequently added to the plots, and either left as a mulch or incorporated into the surface 0.20 m of the soil. Nitrogen was applied to all plots at a rate of 225 kg N ha-1, which represents about one-third of the 500±700 kg ha-1 that was estimated

4、to be required to compensate for N immobilization during decomposition of the woody residues. Survival was good for all treatments, but after 3 years, trees were growing best in areas that were treated with tillage alone. Trees growing on areas where old sawdust was used as an amendment had more vol

5、ume than trees growing in areas where wood chips had been used. Control plots with no treatment had intermediate growth. Soil temperature and chemical properties were evaluated for their effect on growth.#2000 Elsevier Science B.V. All rights reserved.Keywords: Forest soil rehabilitation; British Co

6、lumbia; Soil disturbance; Soil conservation; Soil productivity; Landing and road rehabilitation 1. Introduction Soils on forest landings in central British Columbia are frequently characterized by compaction and nutrient depletion (Carr, 1988a). Degraded soils on landings and other areas where soils

7、 have been disturbed by forest operations often support only meager growth of planted conifers (Arnott et al., 1988). In many cases, soil conditions are so degraded that planting is not attempted on landings. Restoring soil productivity on degraded soils requires that growth-limiting conditions be a

8、lleviated (Bulmer, 1998). Tillage is frequently employed to decompact soils and improve soil productivity(Andrus and Froehlich, 1983). On coarse-textured soils, tillage alone may provide significant benefits for growth of conifers such as lodgepole pine, although the long-term consequences of soil n

9、utrient depletion may be of concern. On fine-textured soils,tillage results have been inconsistent (Carr, 1988b;McNabb, 1994), partly because there is a narrow rangeof moisture content where effective tillage can be carried out, but also because stable aggregates are required to prevent puddling and

10、 poor physical conditions from reappearing shortly after tillage. Stable soil aggregates form when soil mineral grains establish an intimate association with soil organic matter(Tisdall and Oades, 1982). Several approaches could be employed to re-establish stable soil structure after tillage of fine

11、-textured soils. A cover crop of deep rooted grasses and legumes could be established to provide organic matter and enhance biological activity in the root zone,thereby encouraging the development of stable soil aggregates. Another approach that has been proposed involves the incorporation of organi

12、c amendments into the surface soil layer to bring organic and mineral soil materials in contact with each other, and possibly encourage the formation of stable aggregates. This project was developed in order to gain more information about methods for restoring productivity to compact and nutrient-po

13、or soils. We evaluated the effect of several combinations of tillage and the addition of organic amendments on soil properties and the establishment and early growth of lodgepole Pine.2. Materials and methods2.1. Study sitesThe study was carried out on three forest landings 44 km east of Prince Geor

14、ge, in the SBSwk1 biogeoclimatic subzone. Soils were developed from morainal parent materials. The usual surface soil texture was silt loam, but in at least one location, a clay-rich B horizon was encountered. Coarse fragment content varied between 15 and 40%. The landings were located on level or g

15、ently sloping areas. Prior to treatment, there was little vegetation growth on the Landings.2.2. Experimental designNine treatments were applied to 5 m6 m plots, as described in Table 1. Two control plots were established on each landing. The two organic amendments used were wood chips produced as p

16、art of treatments to reduce ®re hazard on the adjacent cutblock, and well-rotted sawdust from an old sawmill site. These materials are typical of soil amendments that may be available at remote rehabilitation sites. The chips had typical particle size of 0.1 m 0.05 m 0.005 m,while the sawdust p

17、articles had all dimensions smaller than 0.003 m. 2.3. TreatmentsTreatments were carried out in the summer of 1994 using an excavator equipped with a five-tooth site preparation rake. Soils were tilled to a depth of 0.50 m, and organic amendments were subsequently shoveled onto the plots to obtain a

18、n even distribution of the material. Amendments were either left as a mulch or subsequently incorporated into the surface 0.20 m of the soil.Pine seedlings (PSB 313) were planted at 1 m spacing on all plots. A legume seed mix was applied in the summer of 1995, but very poor establishment of the legu

19、me cover crop occurred due to dry weather.Grass and legume cover has been maintained at a low level throughout the experiment. All plots, including controls, were fertilized in the summer of 1995, using a combination of urea (45-0-0) and a complete NPK fertilizer (18-18-18). Nitrogen was applied at

20、a rate of 225 kg N ha-1, which represents about one-third of the 500±700 kg N ha-1 that was estimated to be required to compensate for N immobilization during decomposition of the woody residues. The plots received 50 kg ha-1 of K2O and P2O5.2.4. Soil analysis and tree productivity measurements

21、Composite soil samples were collected in October,1994 from the recently treated plots. Samples were air dried, passed through a 0.002 m sieve, and analyzed at the Pacific Forestry Centre. Soil temperature and moisture were evaluated approximately every two weeks during the summer of 1995 by obtainin

22、g three readings with a hand-held thermometer that was inserted 0.15 m below the mineral soil surface. Tree survival and early growth was monitored after one,two, and three growing seasons. Tree height and caliper was determined, along with an assessment of the tree condition. Tree volume was determ

23、ined as the volume of a cylinder with base diameter equal to the caliper, and height equal to the seedling height.3. Results and discussion3.1. Soil properties Soil temperature results are presented in Fig. 1.Even though no analysis was done on the data, and replication was limited, general conclusi

24、ons appear to be justified. Daytime soil temperatures tended to be lower for mulch treatments compared to soils without added amendments. Plots where organic amendmentshad been tilled into the surface had intermediate soil Temperatures. The sawdust had a much lower C : N ratio than the wood chips (F

25、ig. 2), reflecting higher N concentrations for woody materials that have experienced several years of decomposition. P, Ca, Mg and Fe concentrations also appeared to be slightly higher in the sawdust material (data not shown). Concentrations of other elements did not appear to vary consistently betw

26、een the sawdust and wood chip amendments. C : N ratios of surface mineral soils ranged from16.5 to 72.9. Incorporated sawdust increased the C : N ratio of the ®ne fraction of mineral soils compared to plots without added amendments. Incorporated wood chips also resulted in a slight increase in

27、mineral soil C : N, even though the wood chips were generally much larger than 0.002 m. Carbon concentrations of surface mineral soils were affected by several factors,including the presence of buried wood and other organic materials in the untreated landings, and the effect of the organic amendment

28、s on soil C concentrations.Untreated soils at one of the landings had high C concentrations in surface mineral soils, probably resulting from the presence of buried wood and forest floor material. A 0.05 m layer of wood chips is equivalent to an addition rate of 500 m3 ha-1. The chips had dry bulk d

29、ensity of 152 kg m-3, so the addition rate is equivalent to 76 000 kg ha-1 of organic matter, or approximately 44 000 kg ha-1 of carbon. Incorporation of wood chips at a rate of 44 000 kg ha-1 of C into the surface 0.20 m of a hypothetical mineral soil with a bulk density of 1200 kg m-3, would incre

30、ase the C concentration by 1.8%. Only a portion of this C would end up in the ®ne fraction of soil in the first few years after treatment, but all of it is expected to become part of the soil carbon cycle, and portions will eventually contribute to the ®ne soil organic matter content. In c

31、ontrast, sawdust incorporation would be expected to result in similar changes to total C concentration, but the C would appear in the fine soil fraction sooner,because the initial particle size is much smaller for sawdust than for wood chips. As expected, Fig. 2 shows that the plots where sawdust wa

32、s incorporated into the surface had higher organic matter levels in the surface mineral soils than other treatments. Concentrations of other nutrients in surface mineral soils were variable, and did not show obvious trends arising from the treatments.3.2. Tree survival and early growth Seedlings on

33、plots with tillage alone produced the most volume over the 3 year period (Fig. 3). Trees growing in plots where sawdust was used as an amendment tended to have more volume after 3 years than trees growing where wood chips were used as the amendment. Heavy applications of wood chips left as a surface

34、 mulch resulted in the lowest volume growth after 3 years. Survival rates were over 90% for all treatments (Fig. 4). The silty soils were prone to frost heave, and high mortality rates and seedling damage due to frost heave were observed on control and tilled only plots on a wet area of one landing

35、where seepagewater was present, while lower rates were observed for adjacent plots that had received organic amendments.Although data on soil moisture content are not presented here, several effects of the treatments on soil moisture status and availability to tree roots could be considered as causi

36、ng the observed growth response. Lower soil moisture contents may result from better drainage from areas with raised surfaces, resulting in warmer soil temperatures and increased aeration of the root zone. During dry periods,increased soil organic matter contents of soils treated with sawdust or chi

37、p incorporation may improve soil moisture retention and provide moisture for plants.Surface mulches can also enhance moisture retention,although mulches also insulate the surface and may result in lower temperatures. Several factors, including the extent of summer drought during a particular year wo

38、uld determine the beneficial or detrimental effects of variations in soil moisture storage or altered thermal properties on seedling growth. In general,only minor summer moisture deficits are experienced in the SBSwk1.4. ConclusionAfter 3 years, trees were growing best in areas thatwere treated by t

39、illage alone, and trees growing onareas where old sawdust was used as a soil amendmenthad more volume than trees growing in areas wherewood chips were used as a soil amendment. Controlplots with no treatment had intermediate growth. Soiltemperature appears to have a large influence on treegrowth rat

40、es on these plots. Survival after 3 years was high, indicating that commonly available techniques for landing rehabilitation can restore soil conditions to a state suitable for establishment and early growth of conifer seedlings. Some of the variation in early growth results may relate to difference

41、s in initial conditions on the landings.The results also likely reflect the condition of the planting stock shortly after leaving the nursery, along with conditions at the time of planting. These effects have diminished after 3 years and significant treatment effects were observed. Treatment effects

42、 are expected to become even more dramatic in subsequent years as the establishment effects diminish further. The old sawdust had chemical (low C : N) and physical (smaller particle size, expected higher water holding capacity) that may be implicated in the improved growth, but the data available to

43、 date and analyses that have been carried out so far do not allow further interpretation of the cause for the improved growth of trees on the plots treated with sawdust.Acknowledgements Funding for establishment of this project in 1994and 1995 was provided by a grant from Canada's Green Plan to

44、the Canadian Forest Service. Since1996, continued measurements have been made possible by the BC Ministry of Forests. Support for this project was also provided by Carrier Lumber. Field assistance during plot installation and for subsequent measurements was provided by Matthew Plotnikoff and Colin P

45、eters. ReferencesAndrus, C.W., Froehlich, H.A., 1983. An evaluation of fourimplements used to till compacted forest soils in the Pacificnorthwest. Res. Bull. 45. For. Res. Lab., Oregon StateUniversity, Corvallis, OR.Arnott, J.T., Carr, W.W., Waines, A.C., 1988. Establishing forestcover on winter lan

46、dings in the central interior of BritishColumbia. For. Chron. 64, 121±126.Bulmer, C.E., 1998. Soil rehabilitation in British Columbia: aproblem analysis. Land Manage. Handbook 44. BC Min. For.,Victoria, B.C.Carr, W.W., 1988a. Nutritional and soil compaction aspects ofestablishing forest cover o

47、n winter landings in the Fort St.James area. FRDA Report 047. BC Min. For. and Can. Fore.Serv., Victoria, BC.Carr, W.W., 1988b. The rehabilitation of degraded forest soil inBritish Columbia: an overview. In: Lousier, J.D., Still, G.W.(Eds.), Degradation of forested land: forest soils at risk. Proc.1

48、0th BC Soil Sci. Workshop, February, 1986. Land Manage.Rep. No. 56. BC Min. For., Victoria, BC, pp.197±204.McNabb, D.H., 1994. Tillage of compacted haul roads and landingsin the boreal forests of Alberta. Canada. For. Ecol. Manage. 66,179±194.Tisdall, J.M., Oades, J.M., 1982. Organic matte

49、r and water stableaggregates in soils. J. Soil Sci. 33, 141±163. 挖掘机开垦森林土壤与修正方案BC省的森林,卡拉玛卡研究站,水库路3401,弗农,加拿大不列颠哥伦比亚省c7 V1B 2 审核1999年10月6日。摘要：在1994年初发起的一个研究项目评估成功的几种技术，旨在恢复瓦马瓦马溪以东44公里附近中环不列颠哥伦比亚省乔治王子上岸退化土壤生产力。土壤从材料开发，通常表面土壤质地为粉质壤土。两个有机修订这项研究中，包括新制的木屑和旧木屑。一台挖掘机配备整地耙来耕地土壤深度0.50米。随后添加有机添加物的地块，要么离开覆

50、盖或纳入0.20米的土壤表面。氮225公斤每公顷的速度被应用到这次研究，据估计500±700公斤公顷的约三分之一，被要求固定应用为在木质残留物的分解。挽救措施是处理好了，但3年后，树木的长势最好的领域分别用单独耕作。老锯末作为一项修正案量比在木片的地方已被用于生长的树木有更多的树木生长。没有治理的对照地块中间有增长。土壤温度和化学性质进行了其对经济增长的影响评估。2000 爱思唯尔科学BV保留所有权利1.介绍：众多的特点，在不列颠哥伦比亚省中部的森林着陆土壤板结，养分耗竭（卡尔，1988a）。退化的土壤上和其他地区的土壤已经不妥善的森林经营活动往往只支持种植针叶树（Arnott等人，

51、1988）轻微增长。在许多情况下，土壤条件退化，种植不试图上岸。土壤生产力恢复退化的土壤上生长限制条件得到缓解（布尔默，1998）。经常采用松软土壤耕作，提高土壤的生产力（安德鲁斯和弗勒利希，1983）。在粗质地的土壤，耕作可提供黑松等针叶树的增长，虽然土壤养分长期枯竭的后果可能会是关注的问题。在®NE质感土壤，耕作结果不一致（卡尔，1988B;麦克纳布，1994年），部分原因是一个狭窄的范围内可以进行有效的耕作，水分含量，而且还因为稳性团聚体需要防止耕作后不久再次出现树体状况不佳。稳定的土壤团聚形成土壤矿物颗粒时，建立土壤有机质（蒂斯和奥德的，1982年）。有几种方法可以重新建立稳

52、定的土壤后免耕土壤结构。根深蒂固的牧草和豆科植物可以建立覆盖作物根区域中提供有机质和提高生物活性，从而鼓励发展稳定的土壤团聚体。已经提出的另一种涉及到土壤表层带来土壤有机和无机材料相互接触方法，并有可能鼓励掺入有机物稳性团聚体的形成。 这个项目是为了获得更多的信息的方法恢复紧凑、贫营养的土壤生产力。我们对土壤理化性质评估性耕作，并建立和早期生长的黑松添加有机添加物的几种组合的效果。2. 材料与方法2.1研究网站这项研究进行了三个森林着陆乔治王子市以东44公里，在生物地球化学气候分区。土壤开发的材料。通常的表面土壤质地为粉砂壤土，但至少有一个位置，遇到富含粘土的B层。粗碎屑含量介于15和40。着

53、陆位于水平或平缓地区。处理之前，很少有植有生长。2.2实验设计9个5米x6米处理应用，如表1中所述。两个控制地上建立每次着陆。两个有机添加物使用木屑作为处理的一部分减少®相邻的切口块重再次危害，以及旧锯木厂腐烂的木屑。这些材料是典型的土壤改良剂，可能是远程康复站点。该模片有典型的颗粒尺寸为0.1mx 0.05米x 0.005米，而木屑颗粒有所有尺寸小于0.003米。2.3治理在1994年的夏天进行治理使用的挖掘机配备一个®VE齿整地耙。土壤耕种的深度0.50米，有机修正随后铲到地块，以获得均匀分布的材料。修订要么离开覆盖或随后并入0.20米的土壤表面。所有种植松苗（PSB3

54、13）的地块树苗在1米的间距。豆科植物种子组合被应用在1995年的夏天，但是非常贫瘠的土地由豆科植物建立作物覆盖，由于天气干燥，在整个实验草和豆科植物一直维持在一个较低的水平。在1995年的夏天，所有的细节，包括控制，受精使用尿素（45-0-0）和一个完整的氮磷钾复合肥（18-18-18）的组合。适用于氮气225公斤每公顷，据估计约占500±700 KGN公顷比例的三分之一，以固定在分解的木质残留物作为补偿。该地块收到50公斤K2O和P2O5每公顷。2.4土壤分析和树生产力测量1994年10月采集复合土样，从最近处理的情况。样品在空气中干燥后，通过0.002筛，并在起搏®C林业中心分析了。土壤温度和湿度在1995年夏天