城市森林对周边小气候时空格局的影响

以对城市森林生态效应的动态评价为目的,研究绿地和非绿地之间的物质交换特点与规律,描述和揭示植物群落的生态效应时空格局。试验对森林周边温度和湿度在空间和时间的梯度变化进行测试。结果表明,杨树林对其周边环境有着明显的降温和增湿效应,中午时段绿地生态场效应最高,下午测试时段对周边空气温湿度的影响与常规是逆反的。     

Experimental Results on the Effects of Nonregular Spatial Patterns of Plants on Yield per Area

Based on several simplifying assumptions, a stochastic approach was developed which allows an estimation of the effects of nonregular spatial patterns of the distribution of individual plants on yield per area (F). In this approach, two random variables were attached to each plant: single plant yield (E) and individual space per plant (A). The latter was estimated by the area of Thiessen polygons. Yield per area was calculated theoretically by the expectation of the ratio E / A. Appropriate approximations of this expectation depend on the means (ē and ā), coefficients of variation (vE and vA) of E and A and their correlation (rEA). Yield per area can be decomposed into two additive terms: the first term gives the commonly used estimate ē/ā— or h(ā)/ā if a functional relationship between E and A is assumed: E = h(A). In this study, the two relationships E = k1 + k2 · ln A and E = A/(k3 + k4A) were used (with appropriately chosen constants k1, k2, k3, and k4). The second term in the decomposition of F can be interpreted as the effect of variable individual plant spaces on yield per area. In this paper, all theoretical concepts and results were applied to 17 experimental data sets of three cultivars of winter oilseed rape (Brassica napus L.). Single plant yields (E) and individual plant areas (A) were positively correlated with correlation coefficients from 0.64 up to 0.91. The ranges for both coefficients of variation were similar: 0.27 ≤ vE ≤ 0.65 and 0.28 ≤ vA ≤ 0.59. One obtains no significant differences in the goodness-of-fit for both tested relationships between E and A although the logarithmic relationship seems to be slightly superior. For only three data sets one obtains negative values for the percentage of the second term in the decomposition of F. This indicates an overestimation of yield per area by the commonly used estimates h(ā)/ā and ē/ā, respectively. These overestimations, however, are less than 5 %. In all other cases with positive values for the second term the yield per area is underestimated by the common estimates. For almost all data sets, however, the percentages of F which are explained by the common estimates are much larger than 90 %.     

Irrigation Water Management for Efficient Water Use in Mulched Onion

Caused by the necessarily imperfect seed placement accuracy of sowing machines and, additionally, caused by many other biotic and abiotic factors, the resulting plant stands exhibit nonregular spatial distributions of its plants. Based on several simplifying assumptions, a stochastic approach is developed which allows an estimation of the effects of nonregular spatial patterns on yield per area. In this approach, two random variables are attached to each plant: single plant yield E and individual space A . The latter is estimated by the area of Thiessen polygons. Yield per area, calculated by the expectation of the ratio E/A , can be approximately expressed dependent on the means ( Ē and Ā ) and coefficients of variation ( v _E and v _A ) of E and A and their correlation ( r _EA ). In relation to the commonly used estimate Ē/Ā for yield per area, one obtains yield decreases if v _A / v _E  <  r _EA . This inequality, however, will be usually valid in the field of applications. The theoretical approaches and results were applied to three experimental data sets for drilled seeds of winter oilseed rape ( Brassica napus L.) (plant density: 60 plants m⁻², row distance: 10 cm). These data sets are characterized by different accuracies of longitudinal distributions within rows (58 %, 101 %, 150 %): yield depression increases with an increasing variability of plant distances within rows.     

沙漠绿洲地区膜下滴灌棉花产量和氮素利用的水氮耦合效应

研究施肥量和灌水量对膜下滴灌模式棉花氮素利用效率(NUE)的水氮耦合效应的影响。试验设置1带4行、2带4行、2带6行3种滴灌模式,灌水量和施氮量采用二次通用旋转组合设计,进行大田小区膜下滴灌棉花试验。结果表明,1带4行灌水量对棉花产量的影响大于施氮量,2带4行和2带6行施氮量对棉花产量的影响大于灌水量。3种滴灌模式棉花产量与灌水量呈显著正相关。棉花产量与施肥量,1带4行呈显著的正相关,2带4行在施氮量为27.6~69.0 kg/hm2呈负相关,施氮量为69~94.2 kg/hm2呈正相关。2带6行施氮量为27.6~55.2 kg/hm2呈正相关,施氮量为55.2~94.2 kg/hm2呈负相关;灌水量和施肥量对棉花氮素利用效率的影响,3种模式均为施氮量大于灌水量。氮素利用效率与施氮量的关系,1带4行和2带4行在施氮量为27.6~82.2 kg/hm2呈负相关,施氮量为82.2~94.2 kg/hm2呈正相关,2带6行呈负相关。3种滴灌模式氮素利用效率与灌水量呈正相关;根据不同滴灌模式对水氮耦合效应,建立以棉花产量、NUE为目标的不同滴灌模式水氮管理策略。     

肥皂草的嫩枝扦插繁殖和栽培管理技术

太原市植物研究中心2005年从东北引进了新优地被植物肥皂草,它有很高的观赏价值和生态效益。通过近4年的引种试验,证明该品种适应太原地区气候和土壤条件,是很有发展潜力的优良绿化地被品种。对肥皂草进行嫩枝扦插繁殖试验,结果表明,用浓度为500 mg/kg的NAA处理4 h,肥皂草扦插生根率和成活率能达到90%以上,成活率很高。并对其栽培管理技术进行了总结。     

Interactions between fishing strategies of Nephrops trawlers in the Bay of Biscay and Norway lobster diel activity patterns

Abstract  Norway lobster, Nephrops norvegicus (L.), in the Bay of Biscay exhibited diel activity patterns with more individuals outside their burrows at dawn and dusk, increasing catchability at these times. Data from an on board observer programme on Nephrops trawlers between 2002 and 2005 were used to assess variability in catchability in commercial catches. Catch numbers per haul varied spatially and between months, but no signal for diel variations was found. Fishing strategies developed by the Nephrops trawlers had several components. On a seasonal level, they started around sunrise. On a haul level, haul duration decreased from haul to haul, with the longest hauls taking place at the time of the highest catchability. By-catch of hake, Merluccius merluccius (L.), increased more than proportionally with haul duration.     

南川百合与泸定百合种群格局分形特征的分析

本文应用计盒维数和信息维数比较分析了南川百合与泸定百合种群的空间分布格局及其分形特征。研究显示，南川百合与泸定百合种群的计盒维数和信息维数均较小（〈1．5，远离2），说明其占据生态空间的能力和格局强度都不大，体现其在群落中的劣势伴生地位。在2006年，南川百合各种群的平均计盒维数（0．7232）比泸定百合（0．7734）小0．0502，而其平均信息维数（0．4179）却比泸定百合（0．2381）大0．1798，这些数据表明，南川百合种群占据生态空间的能力比泸定百合弱，但其种群格局强度要比泸定百合种群大得多。在高温干旱的2006年，这两种百合的计盒维数与2005年相比都有所减少，信息维数都有所增加，但南川百合种群计盒维数的减少比例（13．87％）大于泸定百合（8．97％），约为泸定百合的1．54倍，其信息维数的增加比例（6．830%）却小于泸定百合（33．02%），泸定百合种群信息维数的增加量是南川百合种群的4．98倍，这些数据表明，高温干旱天气对这两种百合的生长均有影响；泸定百合的抗热抗旱能力要高于南川百合，南川百合更易受高温干旱天气的伤害。由于人为干扰和气候等环境因子的变化，南川百合和泸定百合均出现濒危迹象，此外，因南川百合抗热抗旱性能不强、占据生态空间能力弱等，导致其更加处于濒危状态，应尽快加以保护。     

宁夏东部荒漠草原猪毛蒿光合特征和水分利用效率对降水变化的响应

荒漠草原植物的生长和生存受降水影响很大,本研究以宁夏东部荒漠草原猪毛蒿种群为研究对象,2017-2020年连续4年监测了降水改变条件下土壤水分特征,测定了猪毛蒿净光合速率、蒸腾速率、气孔导度和胞间CO₂浓度等光合特征,并对其内禀水分利用效率和瞬时水分利用效率进行了分析。研究表明：4年中无效降水事件（<5 mm）发生次数较多,占当年降水频次的60.00%~82.54%;大雨（≥25 mm且≤49.9 mm）和暴雨等级（≥50 mm）降水事件较少,平均单次降水事件的降水量仅为3.3~6.5 mm·次^-1。不同处理各土层的土壤含水量存在较大差异,表层（10 cm）土壤含水量较次表层（20 cm）和深层（60 cm）的变幅大;次表层（20 cm）土壤平均含水量低于表层,与小降水事件发生频次较高无法入渗补给以及植物吸收消耗有关;深层（60 cm）土壤含水量变化小,较稳定。净光合速率随着光合有效辐射的增加而增大,当光合有效辐射在400~1600 μmol·m^-2·s^-1时,增雨处理提高了猪毛蒿的净光合速率;在光合有效辐射>1600 μmol·m^-2·s^-1时,猪毛蒿净光合速率有下降趋势,且增雨处理下降幅度最大。光合有效辐射在>400 μmol·m^-2·s^-1时,胞间CO₂浓度呈直线下降,达到1600 μmol·m^-2·s^-1时,胞间CO₂浓度最小。蒸腾速率和气孔导度随着光照强度的增加未有显著变化,但增雨处理下猪毛蒿的蒸腾速率和气孔导度均大于其他处理。气孔限制值随着光合有效辐射的增加呈上升趋势,同时降水的增加减小了气孔限制值。猪毛蒿的内禀水分利用效率和瞬时水分利用效率均在较低的光照强度时（<400 μmol·m^-2·s^-1）随着光强的增加而迅速增大,之后增速减缓。各处理中猪毛蒿最大内禀水分利用效率和最大瞬时水分利用效率在1600~2000 μmol·m^-2·s^-1时达到最大。随着干旱程度的增加,猪毛蒿最大水分利用效率对应的光照强度由2000减小至1600 μmol·m^-2·s^-1。在荒漠草原,当光照强度>400 μmol·m^-2·s^-1时,适度干旱提高了猪毛蒿的水分利用效率。     

对退耕还林工程中种草的探讨

分析种草在退耕还林工程中的重要地位和作用，提出退耕种草的草种选择和种植模式，并探讨发展草产业的途径和方向。     

树莓在贵阳地区引种栽培情况初报

2000年从中国林科院森林生态环境研究所引种树莓2个系列6个品种。经比较，有4个品种值得在贵州推广。其果实在6月上中旬成熟，单果平均重6.2g，可溶性固形物含量平均10.3%，味酸甜，风味独特，适应性广。