直干型大叶相思在南宁的引种与生长研究

8年的引种试验表明,直干型大叶相思主干较通直,适应性强,生长迅速,年平均高生长达2.9 m,胸径达2.4 cm,蓄积量年生长量可达16.77m3/hm2;可推广建立速生丰产工业用材林和贫瘠立地绿化造林。     

An allometric equation for estimating stem biomass of Acacia auriculiformis in the north-eastern region of Bangladesh

Tree biomass plays an important role in sustainable management and in estimating forest carbon stocks. The objective of this study was to select the best model for measuring stem biomass of Acacia auriculiformis in the study area. Data from five hillocks and 120 individual trees from each hillock were used in this study. Twelve different forms of linear, power and exponential equations were compared in this study to select the best model. Two models (VI and XI) were selected based on R ², adjusted R ², the Akaike information criterion, F-statistics and the five assumptions of linear regression. Model VI was discarded based on the Durbin-Watson value of autocorrelation of the residuals, then the ARIMA (2, 0, 1) model was used to remove the autocorrelation from the model and the final bias-corrected model XI was derived. The model was validated with a test data set having the same range of DBH and stem height of the training data set on the basis of linear regression, Morisita's similarity index, and t-test for mean difference between predicted and expected biomass. A comparison between the best logarithmic and non-linear allometric model shows that the non-linear model produces systematic biases and overestimates stem biomass for larger trees. The overall results showed that the bias-corrected logarithmic model XI can be used efficiently for estimating stem biomass of A. auriculiformis in the northeastern region of Bangladesh.     

Gum arabic yield in differently managed <Emphasis Type="Italic">Acacia senegal</Emphasis> stands in western Sudan

A comparative study of gum arabic yield trends per tree and picking in relation to stand management (by farmers and by researchers) and type (natural and planted) was conducted at two locations in North Kordofan, Sudan, for a three-year period. In addition, eight-year yield trends in relation to rainfall were compared based on the 1993–2000 gum yield data from 1440 trees. Although the gum arabic yield followed the same trend over time in all stands at both locations, the gum yield from farm stands, whether planted or natural, was 47% to 60% lower than that from research stands. Late tapping reduced the gum yield by 40% and 50% at the two different locations, respectively. Yield was highly affected by rainfall, correlating positively with annual rainfall in six of the eight years of the study. These findings can be used for improving gum arabic yield through management interventions and for predicting yield in relation to stand type, management regime and rainfall.     

Environmental and demographic correlates of tree recruitment and mortality in north Australian savannas

Tropical savannas cover approximately 20% of the earth’s land area, and therefore represent an important carbon store. Under scenarios of future climate change it is thus important to understand the demographic processes determining tree cover, namely tree recruitment, growth and mortality. This study measured tree recruitment and mortality in 123 (0.08 h) plots in Kakadu, Nitmiluk and Litchfield National Parks, in the Australian monsoonal tropics, over two consecutive 5-year intervals. Plots were located in two important habitats, both dominated by eucalyptus—lowland savanna and savanna growing on sandstone plateaux. All trees with diameter at breast height (DBH) ≥5 cm were tagged and identified. Recruitment was calculated as the proportion of tagged trees present at the end of an interval that were not present at the beginning. There were a total of 6666 and 6571 tree-intervals for mortality and recruitment, respectively. We used Akaike Information Criterion (AIC)-based model selection and multi-model inference to relate tree mortality and recruitment to fire frequency, mean annual rainfall (MAR), stand basal area, tree density and eco-taxonomic group. Recruitment decreased with tree density in both savanna types, and in lowland savanna, with the frequency of fires. In sandstone savanna, recruitment increased with MAR. Effects of fire on recruitment were better explained by season than severity of fire, while fire severity had a stronger influence on mortality. Mortality decreased with tree size up to about 25 cm DBH, but increased sharply when DBH exceeded 50 cm. Mortality increased with stand basal area, and increased with the frequency of late dry season fires in lowland savanna only. There was little evidence that mortality was affected by the frequency of early dry season fires or MAR. Both recruitment and mortality rates were higher for Acacia and Proteaceae species than for pantropical or Myrtaceae (including Eucalyptus) species. We identified several negative feedbacks, mediated by changes in tree density and stand basal area that help confer long-term stability to savanna tree cover. Nonetheless, changes such as a long-term increase in MAR or an increase in frequency or severity of fires are likely to result in changes in tree density, stand basal area and therefore carbon storage potential of savannas.     

Determining the effect of tree size,bark-wood bond strength and tree form on the productivity of an excavator-based harvester in Acacia mearnsii in the KwaZulu-Natal forestry region of South Africa

The aim of this study was to determine the effect of tree size, bark-wood bond strength and tree form on the productivity of cut-to-length harvesting of Acacia mearnsii, using an excavator-based harvester with a SP Maskiner harvester head in the KwaZulu-Natal forestry region of South Africa. Tree diameter and height measurements were used to determine individual tree volumes, after which the trees were classified into different bark-wood bond strength and tree-form classes. Time studies were carried out to determine harvester productivity. The results showed that tree size plays a crucial role in the productivity of the harvester, but bark-wood bond strength and tree form also influence productivity. The harvester productivity varied from 5.5 m³ per productive machine hour (PMH) in 0.05 m³ trees to 16.9 m³ PMH^?1 in 0.25 m³ trees The bark-wood bond strength did not influence harvester productivity when handling small trees of less than 0.1 m³. In small trees, the productivity of the harvester was also not affected by different form classes, but as tree size increased, there was greater productivity variation between the different form classes.     

"宫胁生态造林法"在上海外环环城绿带建设中的应用

<正>"宫肋生态造林法"具有建设成本低、后期管护少等优点,可以成为环城绿带建设的可选模式之一。目前,"宫胁生态造林法"已在世界各地被广泛应用,在我国北京、青岛、宁波、马鞍山、上海浦东等地,也成功地用于荒山植被恢复、高速公路绿带建设以及城市绿化建设。 "宫胁生态造林法"的理论基础是潜在植被理论和 理论,它提倡应用顶级群落的组成种采用容器育苗等"模拟自然"的手法和技术,通     

光肩星天牛成虫寄主选择中的"记忆效应"

2004年和2005年,对羽化于5种树种的光肩星天牛成虫在5种相同寄主树种上的停留、取食、交配、刻槽、产卵等5个寄主选择指标进行了试验.从总体结果看,光肩星天牛成虫在进行寄主选择时,对原寄主具有一定“记忆效应”.具体来讲,受到嗜好树种复叶槭的影响,来源不同的光肩星天牛成虫在停留、取食和交配3个指标上没有表现出很强的“记忆效应”.但就刻槽和产卵两个指标而言,光肩星天牛成虫在其来源树种上的比率最高,“记忆效应”表现得十分明显.该结果为在多树种合理配置中发挥诱饵树作用提供了较好的理论依据.     

沈阳市6种行道树对紫外辐射屏蔽效应的研究

应用便携式紫外辐照计测定银杏、银中杨、垂柳、垂榆、梓树和京桃6种行道树树冠及其单叶对紫外辐射的屏蔽效应。结果表明：各树种紫外线辐射强度的日变化呈倒＂U＂字型,绿叶屏蔽紫外辐射的效果要好于黄叶。6个树种均表现出良好的紫外辐射屏蔽功能,67%以上的紫外辐射被屏蔽,屏蔽效应大小依次为：京桃〉垂榆〉梓树〉银杏〉垂柳〉银中杨。     

周山森林公园不同林木生长对土壤氮的动态影响

在河南洛阳周山森林公园,2009年不同时期对紫叶李(Prunus cerasifera Ehrhart)和塔柏(Sabina chinensis)不同立地林地土壤全氮含量进行了测定,结果表明:紫叶李林地土壤中全氮的含量高于塔柏林地含量,无论平地坡地皆是如此。在不同月份或季节,前者全氮的含量高于后者,且波动幅度较后者大。同时土壤中全氮含量也受地形的影响,平地的全氮含量高于坡地。不同深度,0~10cm土层,平地和坡地的差距最大,随着土层深度的增加,差距逐渐缩小,20~30cm土层,已无明显差异。总体来看,紫叶李平地和坡地土壤氮元素的含量变化要比塔柏平地和坡地土壤氮元素含量变化显著。     

Water consumption of a single tree from the main afforestation tree species in Western Shanxi Province, a loess area

Water is the key factor in vegetation growth in a loess area. Researchers have been keen on the study of tree transpiration for a long time. To provide a scientific basis and practical instruction for vegetation reconstruction and recovery in a loess area, the paper measured and calculated the water consumption of potted Platycladus orientalis, Robinia pseudoacacia, Armeniaca vulgaris and Pyrus hopeiensis separately during the growing season (from Apr. to Nov.). The four were the main afforestation species in a loess area of western Shanxi based on the principle of water balance. Using data on soil water dynamics and the range of available moisture on potted mature trees, the relationship between water supply and consumption and soil moisture availability and deficit state were analyzed. Several conclusions are listed as follows: 1) In the dry year (2002), during the growing season the precipitation was 430.7 mm and the water consumption of potted trees was from 430 to 490 mm. More water consumption and less available water supply occurred, showing a serious water deficiency. In the rainfall-rich year (2003), during the growing season the precipitation was 870.2 mm and the water consumption of potted trees was from 480 to 515 mm. Due to the uneven distribution of rainfall, the water budget balance was slightly affected in May and November. 2) The curves of soil water content of different species had similar annual changes, although the trends were different in the same month, and those of the same tree species in different test plots also had different trends in the same month. 3) Non-available soil water content of Platycladus orientalis, Robinia pseudoacacia, Armeniaca vulgaris and Pyrus hopeiensis was less than 8.0%, 8.4%, 9.2% and 9.7% respectively, which indicated that Pyrus orentalis used water more efficiently than the others. In the dry year (2002), for several months, soil water content of potted trees was lower than its threshold value for non-available soil water content, which could influence the healthy growth of trees. After supplements of precipitation of winter in the year and spring in the next year, soil water content was higher than the lower limit of soil readily available moisture content, which implied that a balance between inter-annual water supply and consumption could be maintained. __________ Translated from Scientia Silvae Sinicae, 2006, 42(9): 18–23 [译自: 林业科学]     

福州地区人工杉木林分蓄积量表的研究

本文提出以林分构成因子——林分胸高总断面积及林分平均高，估计林分蓄积量的办法，选取９种方程求解参数，配合了最优林分蓄积量经验方程，制定出《福州地区人工杉木林分蓄积量表》，对完善我省林业数表的种类、形式和内容，进行了初步尝试。     

Impacts of increased fire frequency and aridity on eucalypt forest structure,biomass and composition in southwest Australia

Water stress and fire disturbance can directly impact stand structure, biomass and composition by causing mortality and influencing competitive interactions among trees. However, open eucalypt forests of southwest Australia are highly resilient to fire and drought and may respond differently to increased fire frequency and aridity than forests dominated by non-eucalypt species. We measured the variation in stem density, basal area, stand biomass, sapwood area, leaf area and litterfall across 16 mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest stands along an aridity gradient in southwest Australia that had variable fire histories. Fire frequency was defined as the total number of fires over a ∼30-year period and aridity as the ratio of potential evapotranspiration to annual precipitation. Total stand biomass and sapwood area were predicted from diameter at breast height of individual jarrah and marri trees using allometric equations. Leaf area was estimated using digital cover photography. More arid and frequently burnt stands had higher stem density, especially of smaller trees, which were mainly jarrah. Overall, both standing biomass and leaf area decreased at more arid sites, while sapwood area was largely unaffected by aridity, suggesting that these stands respond to increased water limitation by decreasing their leaf area relative to their sapwood area. Biomass of marri was reduced at more arid and, to a lesser extent, at more frequently burnt stands. However, total stand biomass (jarrah and marri) and leaf area index did not vary with fire frequency, suggesting that less marri biomass (due to slower growth rates, higher mortality or less recruitment) was compensated by an increase in the density of jarrah trees (regeneration). We conclude that increased fire and drought shift tree species composition towards more fire-resistant species and result in denser stands of smaller trees. In contrast, total stand biomass declines with increasing aridity, but has no association with fire frequency.     

施肥对红松无性系种子园母树结实效应研究

通过在红松无性系幼龄种子园进行的氮肥、磷肥和钾肥3种肥料,每种肥料设置4个水平的施肥试验,研究分析了氮肥、磷肥和钾肥3种肥料,以及每种肥料的不同施用数量,对促进红松无性系种子园幼龄母树结实的效果,提出促进红松无性系幼龄植株结实的适宜施肥数量。     

Predicting Potential Density and Basal Area Development in the Social Forestry Plantations of Acacia nilotica in Gujarat State of India

ABSTRACT

Growth modelling is an important and effective tool for evaluating the effects of a particular management action on the future development of a forest ecosystem. However, such necessary growth models are not available for many indigenous tree species in India. Acacia nilotica is an important multipurpose tree species found in India and growth models are required for proper management of the species in the region. This paper presents equations for estimating potential stand density and predicting basal area in pure even-aged stands of A. nilotica in Gujarat State of India. Although no thinning was suggested, decrease in the number of trees in the stands was observed because of mortality due to overcrowding and some biotic factors. Relationships between quadratic mean diameter and stems per hectare were developed, which was used to establish the limiting density line. Eight different stand level models, belonging to the path invariant algebraic difference form of a non-linear growth function, were compared for projecting basal area. They can be used to predict future basal area as a function of stand variables like dominant height and stem number per hectare and are crucial for evaluating different silvicultural treatment options. The performance of the models was evaluated using different statistical criteria to recommend the suitable model for projecting the basal area in A. nilotica stands.     

The effect of competition on individual tree basal area growth in mature stands of Pinus cooperi Blanco in Durango (Mexico)

In this paper, we evaluated how well-selected distance-dependent and distance-independent competition indices explain individual tree basal area growth of trees, growing in mature and even-aged stands of Pinus cooperi Blanco. A total of 18 competition measures were analyzed of which six do not need tree location (distance-independent) and 12 that utilize tree location (distance-dependent). The competition situation of a stand and/or an individual tree was studied using 11 different competitor selection methods. The mean square error reduction relative to no-competition was used to judge the performance of each competition index. It was found that the best distance-independent competition indices performed as well as the best distance-dependent competition indices. It was concluded that the BALMOD-index would be a good competition index to be incorporated into further individual tree basal area growth models for the study area.

The effect of density after precommercial thinning on volume and structure in Pinus Sylvestris and Picea Abies stands

The interaction between stand density and dominant height and the development of volume, mean diameter, mortality and distribution of volume during a period from precommercial thinning to first commercial thinning was studied on permanent plots in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands in Sweden. The reciprocal equation of the yield density effect was used to level the volume yield. Higher density after precommercial thinning resulted in higher yield and smaller mean diameter. The mortality up to first thinning was low, but is also dependent on density after precommercial thinning. The positive skewness of the volume distribution was higher in denser stands.     

新疆阿克苏地区特色林果适生区区划研究

为了因地制宜、充分合理地利用自然资源,根据主要气候因素对果树的影响情况,对新疆维吾尔自治区阿克苏地区9个县市的气温资料进行了统计分析,并对各县市适宜种植树种的范围进行了人工区划,在此基础上,运用SPSS 18.0软件进行Bayes判别分析,最终确定了阿克苏地区各个县市的适生树种。结果表明:对阿克苏地区各个县市特色林果树种种植影响最大的气温因素是早春极端最低气温,其次为冬季极端最低气温和早春平均最低气温,说明极端低温对果树生长起着关键作用。阿克苏地区适宜种植苹果的县有乌什、温宿、新和、库车;适宜种植香梨的县市有沙雅、阿瓦提、阿拉尔;红枣种植,除乌什、拜城"次适宜"外,其他几个县市均适宜种植;库车最适宜种植巴旦木;核桃种植,除拜城外其他几个县市均适宜种植;杏的种植,除拜城外,其他几个县市均适宜种植;阿月浑子在阿克苏地区的各个县市均不适宜种植;葡萄在沙雅、阿瓦提县均适宜种植。     

长春市主要绿化树种适应低温冻害能力的调查与分析

以长春市部分绿地的主要园林绿化树种为对象,对其适应低温冻害的能力进行了调查与分析,结果表明:在2009～2010年冬春季节持续低温作用下,12种外来树种中未遭受冻害的有青杄等7种,占58.3%;油松、丹东桧柏、大径级垂榆、京桃、刺槐普遍遭受冻害,都有死亡植株发生,其中大径级垂榆冻死率高达63.6%。低温累积效应是导致树木遭受冻害的主要因素,种间的遗传差异亦是因素之一。乡土野生树种无冻害相发生。     

基于混合效应的湖南马尾松次生林单木生长模型

[目的]建立湖南省马尾松次生林单木断面积与材积生长模型,为林木的生长预估提供理论依据.[方法]以湖南省2014年一类清查样地中的20块马尾松次生林为研究对象,选取5个具有生物学意义的生长方程,建立马尾松断面积和材积随年龄变化的基础模型,在此基础上,加入以样地为随机效应的随机参数,构建基于混合效应的湖南马尾松次生林单木断...     

杉松人工林伐区调查设计中树高曲线图的绘制与应用

为提高罗源县杉、松人工林树高曲线图绘制的准确性,利用广泛拟合择优选取的方法确定了能很好描述罗源县杉、松人工林胸径(D)树高(H)的一元二次函数模型,同时利用Excel电子表格设计绘制树高曲线图的程序。研究结果具有较大的应用价值。