不同坡向人工促进天然更新拟赤杨林生长状况比较

调查建宁县采用人促天然更新拟赤杨不同坡向对其生长的影响,结果表明,不同坡向对拟赤杨林生长有明显影响。阳坡、半阳坡比阴坡、半阴坡生长更好。封育15 a形成的天然次生林中阳坡、半阳坡的拟赤杨平均胸径分别为19.7 cm和17.4 cm,平均树高分别为18.8 m和18.1 m,林分蓄积量分别为276.688 0 m~3/hm~2和205.976 0 m~3/hm~2,达到速生丰产林指标。建议在建宁县可以采用人促天然更新培育拟赤杨工业原料林或食用菌专用林,并优先选择阳坡或半阳坡的林地进行培育。     

干旱阳坡刺槐造林技术研究

刺槐是干旱阳坡造林先锋树种之一。为提高造林成活率,保障生态建设质量,在立地条件恶劣的干旱阳坡营造刺槐林时,应选择科学的造林密度,提前1 a或0.5 a于雨季细致整地;第2 a晚秋采用截干方式将壮苗营造在海拔<800m、土层厚度>30 cm的宜林地带,且覆土厚度>7 cm,并需加强抚育管理。     

不同坡向落叶松人工林林分生长模型差异的研究

本文利用红石林业局2016年森林资源调查小班数据库，对落叶松人工林不同坡向的林分生长模型进行了构建，并分析了模型参数差异。结果表明：不同坡向落叶松人工林公顷株数、公顷蓄积量、平均胸径和年龄等主要林分因子差异较小。落叶松人工林林分生长模型为理查德方程，不同坡向模型参数a差异显著，参数b和参数c差异不显著。阳坡、半阴半阳坡和阴坡模型参数a分别为207.7、207.6和181.5,参数b均为0.051 3,参数c均为2.761 6。     

辽西半干旱山地刺槐人工林生长调查

通过对北宁市山地刺槐人工林立地条件、生长规律及生态效益等调查，结果表明，在类似北宁生态条件的半干旱地区的山地，适宜于培养小径级刺槐人工林；造林地要选择在阳坡、半阳坡、山中下腹土层较厚的地块；造林前需要整地；这些地区营造刺槐人工林，有助于保持水土，改良土壤，促进造林地植被变化，恢复和改善生态环境，减少病虫危害。     

核桃园幼树管理技术

一、建园 （一）园址的选择：山地要避开岗、梁，选择坡面的中下部位，以阳坡或半阳坡为好；平地要排水良好，光照充足，土层厚度1．5m以上，质地疏松，PH值6．5～8之间，地下水位在2m以下，最好具备良好的灌溉条件。年平均气温不低于8～12度，最低气温不低于-25度，无霜期120天以上。     

兴隆山桦林人为影响与自然生长观测对比

桦林是兴隆山自然保护区森林类型的重要组成之一,据兴隆山保护区资源本底调查情况,桦林占整个林地面积的43.4%。兴隆山桦林有白桦、红桦林2种,以白桦林为主。白桦林系阳性树种,耐寒性强,对生境适应的幅度较宽,它适生于阴凉湿润、半湿润的生境,亦可生长于较干燥的半阳坡或阳坡。     

杨树烂皮病发生情况调查初报

通过对迎春5号(三北1号)杨树烂皮病(Valsa sordida Nit.)发生情况调查得知，杨树烂皮病的发生主要取决于造林时的环境条件和生物因子，当年新植林发病最重，1a以后逐年减轻。不同土壤比较：白浆土造林发病最重，暗棕壤次之，草甸土最轻；不同地类比较：农田耕地造林病害重于宜林荒山造林；不同坡位病害比较；坡上重于坡中，坡中重于坡下；不同坡向比较：阳坡病情重于阴坡；不同坡度比较：坡度越大，发病越重。     

兴安圆柏压条繁殖技术的研究

2005～2006年对兴安圆柏进行压条繁殖试验,压条前对枝条环切两圈,枝条生根效果最好,可以提高单株生根条数57%,而枝条最佳埋土厚度是20cm,单株平均生根数为30.2条;对枝条不同年龄压条生根条数进行比较,3a、6～8a生枝条均有较高的生根条数,与多年生枝条呈现极显著差异;草甸沙地、固定沙地、干旱阳坡3种立地条件下,枝条平均生根率也呈现极显著差异,生根条数顺序为草甸沙地>固定沙地>干旱阳坡。     

燕山山楂幼树丰产栽植技术

1建园 1．1选择园地可选择土壤疏松肥沃、通透性良好、日照充足、含水量高、保水力强、土壤PH6．5—7．5的平原或坡度15度以下的山地建山楂幼园。但经验证明，在燕山地区，在阳坡的坡根和平原建园生产的山楂质量较高。     

极度干旱沙丘黄柳装瓶埋条造林

在塞罕坝西部的沙丘阳坡 ,土壤中养分稀少 ,又极度干旱 ,干旱季节 0～ 4 5 cm土壤含水量常在 2 %以下 ,而地表温度最高可达 6 5℃以上。第一年经过造林后浇水而成活的苗木 ,翌年或第三年还会大量死亡。 2 0 0 0年春 ,我们用黄柳条基部装瓶埋条造林方法解决了这一难题。具体作法是 :1　采条在天然灌木黄柳树上或基部 ,选择长 80 cm以上 ,基茎 0 .5～ 2 .0 cm的黄柳条 ,要求条基部无杈 ,1～ 3a生。2　装瓶用矿泉水瓶、输液瓶等 ,装满水拧紧盖 ,运往造林地。打开瓶盖 ,将黄柳条基部插入瓶中。3　造林在沙丘阳坡挖深 4 5～ 5 0 cm的造林坑 ,连黄…     

马尾松幼林施肥持续8年的生长效应

１９９２～１９９年在福建省邵武市花岗岩发育的低丘红壤上,对马尾松幼林施肥进行了持续８年的观测研究。结果表明：在第８年时,无论是施Ｐ还是其它肥料,其对总生长量或连年生长量的增长效应已不显著;单施钙镁磷肥或再配合尿素、氯化钾肥料的效应至少可以持续到第６年,至第７年仍维持一定的增长效应;而单施尿素、氯化钾肥料的效应一直均无明显表现。     

建水石质山地两种乔灌混交模式的造林成效

在建水县石质山地进行了墨西哥柏 车桑子混交模式和干香柏 车桑子混交模式的造林试验。6年的试验结果表明:两种乔灌混交模式的造林成活率、保存率均较高,林木的生长状况也较好。前者中墨西哥柏的造林成活率和保存率均为100%,车桑子均为94.44%;后者中干香柏的造林成活率为77.78%、保存率为72.22%,车桑子均为100%。经用层次分析法对两种混交模式的乔灌木层次的明显性、群落的盖度、林木的高生长和径生长等4个方面作比较,得出墨西哥柏 车桑子混交模式的稳定性优于干香柏 车桑子混交模式。由于石质山地的土壤较为瘠薄,影响了乔木树种的生长,使两种乔灌混交林中乔木树种墨西哥柏和干香柏的生长高峰期提前在第3~4年到来。相比较墨西哥柏比干香柏更能适应试验区恶劣的自然条件,其造林后第6年树高和地径生长量仍达0.99 m和1.08 cm,而干香柏只有0.44 m和0.46 cm。     

杨树幼株、苗杆生长及材性差异研究

通过对杨树中汉107号无系性幼林采样测定发现,2～8a生幼树胸径处去皮后木材基本密度、纤维含量、纤维长度都随树龄增加而略增大,分别于第6年、第6年、第5年时基本上稳定下来,达到工艺成熟;幼树木材连年生长量总体趋势是随着年龄的增加而增大,第7年时达到极高值,第8年开始下降。综合杨树不同树龄时生长与木材材性情况,杨树的主伐期定为8a是比较理想的。另外通过对杨树1～5a蔸1a生苗杆的各项指标测定表明:采用“割韭菜”式的经营杨树直接用于制浆、人造板,工艺上是不成熟的。     

Report of a Twelve-year study of Litter Fall and Productivity in a Stand of Mature Scots pine

Litter collections were made in a Scots pine (Pinus sylvestrisL. ) plantation between its first major thinning at 40 years(effectively 35 years because of early stagnation) and its secondthinning at 52 years. The response to thinning was immediatewith no lag phase. Needle production peaked in the third growingseason and remained more or less constant thereafter. Needlebiomass peaked in the eighth year (10. 3 tonnes per hectare)after a year in which the retention of third year needles hadbeen greater than usual. Cone production reached its first maximumin the fourth year, its second in the sixth year, but, thereafter,changed to a three-year cycle: it is suggested that the dipin overall productivity in the sixth and ninth years led tofewer flower bud initials being laid down in those years. Priorityin resource allocation seems to have gone to cone production,once set in train, and then to needle production which stayedup in 1977 (the sixth year) but fell in 1980. Production of litter items was 20 per cent greater than litterfall over the first four years (range –minus; 0. 3% to+plus; 28. 3%) and 0. 4 per cent greater over the last eightyears (range – 14. 5% to +plus; 12. 2%). The differenceswere due in the main to the two-year delay between productionand fall of needles and the one-year delay for cones. However,the differences were not predictable because of greater third-yearneedle retention in certain years and the variable proportionof cones dismantled by squirrels and falling as fragments inthe year of their production.     

Effects of previous N fertilizations on soil‐water pH and N concentrations after clear‐felling and soil scarification at a Pinus sylvestris site

The study describes effects of clear‐felling and soil scarification on the N concentration and pH of soil water in experimental plots previously supplied with different doses of N. The experiment is situated in central Sweden in a former Pinus sylvestris L. stand. Over a 20‐yr period, plots were fertilized three times with ammonium nitrate, resulting in total doses of 360, 720, 1080, 1440 and 1800 kg N ha^‐1. Soil water was sampled at a depth of 40–50 cm using suction lysimeters, and analysed for N and pH. The study covers one growing season before clear‐felling and six and four growing seasons after clear‐felling and soil scarification, respectively. Statistically significant (p < 0.05) elevations in total N and nitrate‐N concentrations were noted in the fourth to the sixth growing seasons after clear‐felling in the plots that had received 1800 kg N ha^‐1, and in the fifth and sixth seasons in the plots that had received 1440 kg N ha^‐1. Ammonium‐N concentrations were not significantly affected. After clear‐felling, total N and nitrate‐N increased with time at a higher rate in the plots that had received 1440 and 1800 kg N ha^‐1 doses compared with the control. In the sixth post‐cutting season, the nitrate‐N concentration was 0.26 mg l^‐1 in the control and between 0.51 and 4.0 mg l^‐1 in the various fertilized plots. Before clear‐felling, a linear relationship between pH and fertilizer dose was absent. After clear‐felling, negative relationships prevailed, but they differed significantly from the pre‐cutting relationship only during the fourth, fifth and sixth post‐cutting seasons. In the sixth post‐cutting season, the pH was 6.0 in the control, and 6.1, 5.7, 5.6, 5.2 and 4.3 in the plots supplied with 360, 720, 1080, 1440 and 1800 kg N ha^‐1 doses, respectively. The absolute difference in pH between the sixth growing season after clear‐felling and period before clear‐felling increased linearly with increasing fertilizer dose (p < 0.05, R ² = 0.79). Before clear‐felling, nitrate‐N was elevated only in the plots that had received 1800 kg N ha^‐1. After clear‐felling, nitrate‐N seemed to increase in all fertilized plots, but the increase began first in the plots receiving the highest fertilizer dose. It was not until the fifth and sixth growing seasons after clear‐felling that nitrate‐N concentrations appeared elevated in all fertilized plots compared with the control. It seems likely that nitrification caused the increases in nitrate‐N because nitrate‐N accounted for most of the variation in pH in the fourth to the sixth growing seasons. Disc trenching was simulated around some of the lysimeters so that 50% of the soil was disturbed. This did not significantly affect the N concentration or pH of the soil water during the first 4 yrs after scarification.     

香叶树人工林木材纤维形态特征的研究

通过对香叶树人工林木材纤维形态的测定表明：香叶树人工林木材在1～3 a间木纤维长度属短;在3～18 a间木纤维长度属中等长度。香叶树人工林木材在1～5 a间木纤维长宽比较小,在6～18 a间木纤维长宽比大于45。     

闽南山地不同立地湿地松生长动态的研究

通过对９株不同立地条件的２０年生湿地松人工林的优势木的树干解析，利用实测数据拟合生长动态方程，结果表明：Ⅰ类地胸径连年生长量最大值出现在第４ａ，Ⅱ、Ⅲ类地出现在第６ａ；树高连年生长量最大值Ⅰ、Ⅱ类地为４ａ，Ⅲ类地较迟，大约在６～８ａ；材积连年生长量在１６～１８ａ达到最大，但在３种立地条件下都未达到数量成熟；利用已有数据拟合出的不同立地生产过程的方程，精确度较高，可供生产上参考。     

鲁西平原毛白杨林地土壤条件与林木生长规律的研究

本项研究主要在山东省冠县毛白杨林场进行,研究了毛白杨片林的林分生长规律、生物量积累及它们与土壤条件的关系。研究结果表明毛白杨生长量在不同土壤上差异甚大,其年平均材积生长量,壤质褐潮土>夹淤沙壤质潮土>通体沙质潮土>粘质褐潮土>风沙土;毛白杨片林数量成熟龄在壤质褐潮土为13a以后,其它几种肥力差的土壤为7-9 a;壤质褐潮土上毛白杨林速生期持续12 a以上,其它几种土壤为4-9 a。据观测毛白杨片林粗生长高峰期显著,5月份粗生长占全年总量40-60％。高生长高峰期持续期较长,为6-7月。毛白杨片林生物量积累随林龄增大而增加,尤其2-10 a增长速度最大,10-14 a以后生物量积累也有所增加,但增加速度减缓。     

秃杉人工林生长过程

用解析木法测定早期引种秃杉林中优势木1株、种源试验林中优势木和平均木各1株,结果表明,秃杉树高生长从5年以后进入速生期,持续至18年生;胸径生长从6年生时进入速生期,持续到20年生;材积生长从14年起进入速生期,至24年生时连年生长曲线仍未与年平均生长曲线相交,还未达数量成熟。用Logistic模型模拟树高、胸径、材积生长进程曲线,确定材积、胸径、树高速生期为13.64,12.77,11.27年。初步确定秃杉8年生以前为幼龄期,8~16年生为速生期,16年生以后为速生稳定期。     

广东省翁源县农业土壤速效钾时空变异特征及其影响因素研究

运用ArcGIS地统计分析方法,对广东省翁源县农业土壤速效钾时空分布特征及其影响因素进行了研究。翁源县1984年土壤速效钾含量变化范围为3.85～235.00 mg.kg-1,大部分地区农业土壤速效钾含量处于四级水平(50～100mg.kg-1),北部地区高于南部地区;2011年全县农业土壤速效钾含量变化范围为4.20～111.00mg.kg-1,大部分地区处于六级水平(小于30mg.kg-1),速效钾缺乏状况严重,分布呈斑块状。研究结果表明,近30年来翁源县农业土壤速效钾含量呈下降趋势,翁西地区下降速率快于东部地区。土壤类型、地形地貌、土地利用方式、施肥管理等因素对农业土壤速效钾含量均有影响。