不同间伐强度对杨桦次生林林下植物多样性的影响

以杨桦次生林为研究对象,采用30-40%强度间伐和20%的中度间伐,以未间伐的林分为对照,研究比较了间伐后1年、2年和5年内的林下植物多样性的变化。结论如下:对于木本植物,间伐显著提高了林下木本植物的盖度(P0.05),其大小顺序为强度间伐中度间伐对照,在间伐后2年、5年差异均显著(P0.05)。对于林下草本植物,间伐显著提高了林下草本植物的种数,尤其在间伐后2年,中度间伐和强度间伐林下的木本植物种数、盖度、Simpson和Shannon多样性指数均显著高于对照(P0.05);但随着间伐时间的延续,中度间伐和强度间伐对草本植物的影响逐渐减弱,其中度间伐林下的植物种数、Simpson和Shannon多样性指数与对照之间未能发现显著差异(P0.05)。     

吉林蛟河不同林分腐木甲虫(鞘翅目)多样性分析

【目的】阔叶红松林是我国长白山林区顶级植物群落,林内动物、植物种类丰富,分析阔叶红松林及阔叶混交林中腐木甲虫物种组成、多样性,以及林分因子对腐木甲虫的影响,有助于揭示腐木甲虫与森林生境变化的相互关系作用机制,为评价天然林在保持腐木甲虫多样性的作用,以及不同生境对腐木甲虫多样性的影响提供依据。【方法】2012—2013年,每年5月中旬—8月下旬的腐木甲虫活跃期,在吉林蛟河阔叶红松林、杨桦林、水胡林中利用飞翔拦截诱捕器持续采集林内腐木甲虫,通过甲虫的生物学、相关文献资料和数据库确定腐木甲虫种类。【结果】共采集到甲虫39个科239种,其中,腐木甲虫203种,7 465个个体;叩甲科、露尾甲科、隐翅虫科和天牛科的数量和种类较多;四星蜡斑甲和条脊甲在本地首次被采集到。阔叶红松林2个林分中腐木甲虫具有较高的多样性,杨桦林和水胡林中多样性相对较低。不同林分对甲虫的物种数、个体数、丰富度指数和多样性指数均有显著影响。阔叶红松林2个林分中甲虫的物种数、个体数、丰富度指数都显著高于杨桦林和水胡林。郁闭度、平均胸径、每公顷蓄积、每公顷株数、灌木盖度对各类群影响不同,林分的郁闭度、平均胸径、公顷蓄积对大多数腐木甲虫有正向影响。【结论】阔叶红松林内腐木甲虫种类和数量比较丰富,林龄、胸径、蓄积高的阔叶红松林林分腐木甲虫具有较高的多样性,其在维持腐木甲虫多样性方面发挥着重要作用。天牛科的物种数、个体数在阔叶红松林林分中数量都高于杨桦林和水胡林。叩甲科是阔叶红松林中最大的类群,与其他类群不同,其在灌木盖度高和乔木株数多的杨桦林数量较多。     

长白山区野生刺五加种群结构与数量特征分析

采用样地调查法,对长白山区野生刺五加种群资源现状、群落特征及种群数量进行研究,分析群落物种丰富度、多样性指数、主要灌木物种的重要值及种群个体数量估算,结果表明:野生刺五加种群主要分布在阔叶红松林、蒙古栎林、杂木林和云冷杉林群落内,阔叶红松林内种群区域分布频度最大,部分区域已形成优势群落。云冷杉林内乔、灌木层Pielou均匀度指数(R)均为最高,灌木层生态优势度指数(SN)、Shannon-Wiener多样性指数(SW)最高,而丰富度指数D2和Hurlbert种间机遇指数(H)最低。杂木林内丰富度指数(D1、D2)最高,蒙古栎林内Hurlbert种间机遇指数(H)最高,说明云冷杉林内刺五加群落相对较为稳定,而其他林内由于人为采挖严重,群落相对不稳定。刺五加在阔叶红松林的灌木层占有较高重要性,重要值最大,其大小依次为阔叶红松林杂木林云冷杉林蒙古栎林。     

辽东山区主要森林类型生物多样性的研究

生物多样性是生物及其环境形成的生态复合体以及与此相关的各种生态过程的总合，森林内生物多样性越大，物种越丰富．分布越均匀时，才可以说此生物群落具有稳定的组成结构，生物多样性对确定合理的林型结构是十分必要的。在5种森林类型中杂木林的生物多样性最好，杂木林中灌木层生物多样性指数和均匀度指数最大，柞树林、红松林、落叶松林和油松林差异不大；草本层生物多样性指数以杂木林最大，红松林下草本植物分布均匀。阔叶林在郁闭度0．6—0．7．针叶林在0．7—0．8时各物种分布均匀，物种丰富度较大，乔、灌、草各层生长状况良好。     

不同间伐强度对长白落叶松-红松林植物多样性和土壤特性的影响

为了提高长白落叶松-红松林的生产力和生物多样性,2005年秋对长白落叶松人工林进行疏伐,伐后林冠下栽植4年生红松。2012年秋又对上层长白落叶松进行生长伐,设计轻度、中度和强度3种间伐强度和1组未间伐林分(对照),分析5年后不同间伐强度对林下植物多样性和土壤理化性质的影响。结果表明:①抚育间伐能提高林下植物多样性,林下灌木层植物丰富度随着间伐强度的增加而增加,轻度、中度和强度间伐差异显著(p<0.05)。林下灌木层植物多样性指数随着间伐强度的增加而增加,对照与中度间伐、强度间伐差异显著(p<0.05),但中度间伐和强度间伐差异不显著。林下草本层植物的丰富度和多样性指数随着间伐强度的增加而增加,各间伐强度均与对照差异显著(p<0.05),但轻度间伐和中度间伐差异不显著。②适度抚育间伐能改善土壤的理化性质,随着间伐强度的增加,土壤容重有所降低,土壤孔隙度和持水量有所提高;土壤pH值呈现先升高后略有降低的趋势,全K、速效K、全P、速效P、全N、速效N含量先升高后略有降低,其中中度间伐效果最好。综合考虑,对长白落叶松林分进行中度间伐较为适宜。     

辽宁东部山区几个主要林型林下植物多样性的初步研究

本文研究了辽宁东部山区４个主要林型的林下植物种类多样性规律。采用了Ｓｈａｎｎｏｎ－ｗｉｎｎｅｒ多样性指数、Ｓｉｍｐｓｏｎ优势度和均匀度等几个主要参数进行计算分析。结果表明，多样性指数为０６６０８～２７８０２，优势度为００７２８～０７３５３。杂木林多样性指数高于其他人工林，落叶松林植物种类多样性高于红松林。随着林龄的增长，落叶松林多样性呈递增的趋势，红松林呈下降的趋势；优势度的变化规律则与此相反。     

间伐强度对云杉人工林下植物多样性的影响研究

调查了云杉人工林间伐后和未间伐的林分生长、林下植物种类、数量、盖度、高度,采用物种丰富度、Shannon-Wiener指数、Simpson指数和Pielou均匀度指数进行了多样性分析,以探讨间伐强度对云杉人工林下植物多样性的影响.结果表明：随着间伐强度的增大,保留木的生长显著优于对照区;林下植物种类、数量显著增加;不同间伐强度林下植物种类的多样性、丰富度、生物量、盖度、显著高于对照区,且随间伐强度的增强而增大,以重度间伐（＜450株/hm2）最为显著（灌木层多样性除外）.     

不同强度间伐对北京山区油松生长及其林下植物多样性的影响

2005年和2006年夏季,对北京密云水漳村和昌平小宫门低山阴坡厚土油松人工林林分的生长及其林下植物多样性变化情况进行抚育间伐后的调查研究.结果表明:间伐后第1、2年,油松林分平均胸径、树高、冠幅、单株材积和蓄积量显著高于对照,但各强度间伐林分之间生长差异不显著;而间伐后第6年,油松林的各项生长指标均表现为强度间伐＞中度间伐＞弱度间伐＞对照,且中度、强度间伐显著大于对照和弱度间伐,强度间伐后林分生长效果最好;林下植物种类、数量、多样性指数、均匀度指数和林下植物总生物量在间伐后第1、2年都随着间伐强度的增加而升高,间伐后第6年,不同强度间伐下油松林的植物种类、多样性指数、均匀度指数均比间伐后第1、2年有所降低,弱度、中度、强度间伐后的林下植物种类比对照分别增加了5、10和18种,多样性指数仍表现为强度间伐＞中度间伐＞弱度间伐＞对照;各强度间伐后林下植物的密度较间伐初期有所减少,植物盖度仍随间伐强度加大而增加,强度间伐后,可明显看出林下植物的结构层次;中度、强度间伐使林下需水性强的植物比例增加,促使油松人工林林下植物向中旱生、中生植物转变;随着间伐强度的增大,油松林林下植物总生物量也增加,且各强度间伐的林下植物总生物量表现为间伐后第6年＞第2年＞第1年;间伐后第6年,弱度、中度和强度间伐的林下植物总生物量与对照相比,分别增加了29.1%、45.2%和70.9%.间伐对油松林分的生长及其林下植物多样性的影响是显著的,对于北京低山阴坡厚土35～37年生密度为3 200～3 467株·hm-2的油松人工林而言,强度间伐最有利于林分的生长和林下植物多样性的提高,经营密度宜为1 240～1 500株·hm-2.     

间伐强度对红松人工林下草本植物多样性及其组成的影响

通过测定和比较红松人工林下光照条件的差异,植被组成及多样性的变化,研究5种不同间伐强度对红松林群落组成的影响。结果表明:随间伐强度增大,林内散射光强度增大,单子叶植物科的数量增多,双子叶植物减少。间伐强度不同,红松林内草本建群种不同。间伐可改变群落的植物多样性、均匀度和丰富度,其中以弱度区最明显。运用关联度分析得出:不同间伐强度红松林下的无截取散射光量对植物多样性各指标影响的大小顺序为丰富度指数>均匀度指数>多样性指数>优势度指数。综合分析认为,合理间伐红松林,使其密度维持在1 000~1 600株.hm-2最有利于维护红松林的稳定。     

不同经营措施对辽东红松林和杂木林土壤物理性质及土壤水分的影响

通过野外实地调查与室内分析,研究了不同经营措施下红松林和杂木林的土壤物理性质、土壤水分变化情况。结果表明:红松林择伐区土壤自然含水量、饱和含水量较杂木林高;土壤容重、总孔隙杂木林高于红松林;红松林内土壤的最大、最小、毛管持水量等指标皆高于杂木林。择伐上层林木栽植的红松林对土壤的改良效果较皆伐造林和直接林冠下造林者好。中度抚育间伐的森林经营措施改良土壤效果显著。     

A succession and silviculture model for the broad-leaved Korean pine forests of Changbai Mountain Area

IntroductionGaPSinforestSwereoftenfomledduetobigtreesfalldown.Regenerationandgrowtl1inthegapsincreasebe-causeofIheAnprovementoflightcondition-Thegapwillbefilledwithnewregeneratedtrees.Wattnamedtl1isforesIdynamicsastheforestgrowtllcycle.SinceD.Bot-kindevelopedthefirstGapmo`Iel(JANOWAnlodel)basedontheforestgrowthcycletheory,dleresearchongapmodelbecameoneofthemostactivedirectio11slilecologybecauseofJANoWAnlodeI'ssuccess.H.Sl1ug-artandhisstUdentSmadegreatc()ntributio11stogapmodeI'sdeve…     

Diversity of polyporous fungi (Polyporaceae) in northern boreal forests: effects of forest site type and logging intensity

The effects of forest site type and logging intensity on polyporous fungi were studied in subxeric, mesic and herb-rich forests and spruce mires in northern Finland. The species richness of polypores did not follow the fertility gradient of the site types, but was connected with the amount and diversity of coarse woody debris (CWD). The total number of species, and the numbers of indicator and threatened species were equal in subxeric pine forests and in more fertile spruce-dominated stands. The species composition of pine-dominated forests differed conspicuously from that of spruce-dominated site types. The total number of species was not affected by logging intensity, but no virgin forest species or threatened species were found on the sites where the number of cut stumps exceeded 150 stumps ha^?1. Increasing logging intensity decreased the number of polypore observations, indicating reduced substrate availability. The results stress the importance of protecting not only fertile spruce-dominated stands, but also poorer, pine-dominated forests, and sites with high and diverse CWD content.     

Diversity of naturally-regenerated native woody species in forest plantations in the Ethiopian highlands

Woody species diversity and ground layervegetation cover were studied in plantations ofPinus patula, Cupressus lusitanica,Grevillea robusta, and Juniperusprocera, and in surrounding natural forests inWondo Genet, Ethiopia. In the understory of theplantations, a total of 53 naturallyregenerated tree and shrub species belonging to31 families were recorded. Important indigenoustimber species were also represented. Treesaccounted for 72% of all naturally-regeneratedwoody plant species. On the average, 78% ofthe woody species found in plantations werealso found in the natural forest. There was nosignificant variation in understory woodyspecies richness among plantations. C.lusitanica plantations had a significantlyhigher abundance of woody species than those ofP. patula, but the difference wasnot significant in relation to J. procera,G. robusta and the adjacent natural forest.The herbaceous ground cover percentage in G. robusta and P. patula stands wasconsiderably higher than in C. lusitanicaand J. procera stands. Relative toplantations of other species, plantations ofthe native tree species J. procera hadhigher understory species richness, mediumwoody species abundance and low ground cover.Although there was a marked variation inoverstory plantation density, its effect onunderstory species richness and abundance wasnot significant. The density ofnaturally-regenerated woody species inplantations was over three times the usualplanting density in Ethiopia, indicating a highpotential of forest plantations for restoringthe natural forest ecosystems on degraded landsat a comparatively low cost.     

Effects of multiple factors on plant diversity of forest fragments in intensive farmland of Northern Portugal

The joint and independent effects of dominant tree species, forest patch spatial attributes, and forest structure and management as drivers of plant species richness and composition in small forest patches scattered within an intensive agricultural landscape were addressed.In a landscape with scattered urban and intensive dairy agricultural areas in north-west Portugal, within which small forest patches (dominated by pines, eucalypts, or both) represent semi-natural habitat islands, 50 small forest patches, with areas ranging between 0.3 and 3 ha, were selected and surveyed for vascular plant diversity, within dairy farming landscape mosaics dominated by annual forage crops. Explanatory variables were composed of three datasets derived either from GIS mapping or field observations: forest type (dominant tree species), forest patch spatial attributes (patch area and shape index), and measures of forest management and structure (diameter at breast height, tree density per hectare, and percentage cover of vegetation strata). Variations in these forest patch attributes were assessed across forest types, and related to measures of plant diversity (total, native, alien, woody, and herbaceous species richness). Redundancy analysis with variance partitioning was applied to evaluate the joint and independent effects of the three sets of variables on species assemblages. The recent shift in canopy dominance from pine to eucalypt observed in the region appears to be related to a (nonsignificant) tendency for the increase of patch area and to the decrease of patch complexity, as well as several changes in forest structure and management, expressed as a trend to denser tree canopies and lower cover of understory plants. Dominant tree species and attributes related to forest structure and management were the most important factors determining plant diversity. The joint effect of the dominant tree species and forest structure and management resulted in lower levels of plant species richness in eucalypt plantations. These were also more prone to invasion by alien species, probably due to decreased biotic resistance from unsaturated native plant assemblages. Our results draw attention to the importance of dominant tree species and management practices for the maintenance of plant diversity levels (species richness and composition) in dairy landscape mosaics, highlighting the importance of the remnants of semi-natural forests as refuges for plant diversity in the landscape context. Nonetheless, forest plant diversity could further be fostered by promoting naturalness of pine stands and the regeneration of native oak woodlands in some forest areas. This would also diversify the range of ecosystem services that could be provided by forest areas in these peri-urban farmlands.     

Floristic and structural patterns along a chronosequence of secondary forest succession in Argentinean subtropical montane forests

We studied forest structure and composition along a chronosequence of secondary forest succession in Northwest Argentina's montane forests (‘Yungas’) at 27°S, between 700 and 900 m. Early herbaceous stages, forested stages of 11, 25, 45, and 50 years after abandonment, and old-growth forests were surveyed. Secondary forests included stands that originated in abandoned herbaceous crops and in abandoned fruit orchards. Basal area and species composition differed between 50-year-old secondary forests and old-growth forests. In contrast, tree density and species diversity were similar in the 50-year-old and in the old-growth forests. The previous use (herbaceous crops or fruit orchards) was an important influence on secondary forest composition. Whereas stands originating in herbaceous fields were dominated by wind-dispersed native species such as Heliocarpus popayanensis, Tecoma stans, Parapiptadenia excelsa, and Tipuana tipu, fruit-orchard-originated stands were dominated by animal-dispersed species. Among the animal-dispersed species, the exotic tree Morus alba was the most abundant, and its abundance in secondary forests seems to slow the succession toward old-growth forest composition. Overall, after accounting for differences attributable to pre-abandonment conditions, secondary forest succession showed a trend toward compositional convergence, with the rate of succession apparently regulated by the demography of long-lived pioneer species.     

Growth Response of Loblolly Pine (Pinus taeda L.) 3–5 Years After Plantation Establishment Using Different Management Intensities

The upward trend of intensive management in Southern pine forests is expected to continue, both in area and intensity level. Much of the Mississippi Lower Coastal Plain (LCP) is managed intensively using some combination of mechanical site preparation, chemical site preparation, and herbaceous weed control (HWC). We studied pine growth response and competition control on loblolly pine (Pinus taeda L.) plantations 3–5 years following establishment using five combinations of chemical site preparation, mechanical site preparation, and HWC. Treatments were designated a priori as 1 (least intensive) through 5 (most intensive) largely on the basis of anticipated impact on the vegetation community. We measured pine height and diameter at breast height (dbh); woody stem density; hardwood basal area (BA); coverage of herbaceous plants, understory woody plants, and pine trees; and estimated differences in pine response using age-shift calculations at age 5. Pine height and dbh were correlated with treatment intensity; treatment 5 maintained an average advantage of 1.4-m height and 2.5-cm dbh over treatment 2, the least responsive treatment. Woody stem density varied widely and was not affected by treatment; understory woody coverage was also unaffected by treatment. Coverage of herbaceous plants was reduced in treatments receiving broadcast HWC, and in treatment 2, where slower establishment of pines may have acted as a release for competing woody plants. Age-shift gains relative to treatment 2 ranged from 0.4–1.0 years. Based on year 5 measurements of hardwood BA, it is likely that treatments 1 and 2 will fall further behind treatments 3–5 as the stands mature. Greatest control of competing vegetation and maximum growth of pines was achieved with the most intensive treatment.     

The role of disturbance severity and canopy closure on standing crop of understory plant species in ponderosa pine stands in northern Arizona,USA

Concerns about the long-term sustainability of overstocked dry conifer forests in western North America have provided impetus for treatments designed to enhance their productivity and native biodiversity. Dense forests are increasingly prone to large stand-replacing fires; yet, thinning and burning treatments, especially combined with other disturbances such as drought and grazing, may enhance populations of colonizing species, including a number of non-native species. Our study quantifies plant standing crop of major herbaceous species across contrasting stand structural types representing a range in disturbance severity in northern Arizona. The least disturbed unmanaged ponderosa pine stands had no non-native species, while non-native grasses constituted 7–11% of the understory plant standing crop in thinned and burned stands. Severely disturbed wildfire stands had a higher proportion of colonizing native species as well as non-native species than other structural types, and areas protected from grazing produced greater standing crop of native forbs compared to grazed unmanaged stands. Standing crop of understory plants in low basal area thinned and burned plots was similar to levels on wildfire plots, but was comprised of fewer non-native graminoids and native colonizing plants. Our results also indicate that size of canopy openings had a stronger influence on standing crop in low basal area plots, whereas tree density more strongly constrained understory plant standing crop in dense stands. These results imply that treatments resulting in clumped tree distribution and basal areas <10 m² ha⁻¹ will be more successful in restoring native understory plant biomass in dense stands. Multiple types and severity of disturbances, such as thinning, burning, grazing, and drought over short periods of time can create greater abundance of colonizing species. Spreading thinning and burning treatments over time may reduce the potential for non-native species colonization compared to immediately burning thinned stands.     

Commercial thinning that maintained species diversity of a mixed black spruce–jack pine stand enhanced productivity

Commercial thinning enables forest managers to meet timber production objectives. Thinning reduces tree density to alleviate competition for resources and favour growth of selected tree species. However, in doing so, thinning can homogenize the composition of mixed-species forests and raise biodiversity issues. There is increasing evidence that species richness can lead to higher productivity through a complementarity effect. Hence, thinning that would maintain species diversity of mixed-species forests could enhance stand productivity and help forest managers to reconcile timber production objectives and biodiversity issues. The objective of this study was to compare post-thinning stand production, experimentally over 10 years, in mixed and monospecific stands of black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). The post-thinning stand production curve of the mixed stand converged toward that of the unthinned mixed stand while the production curves of the thinned and unthinned monospecific stands remained parallel. The convergent productivity of the mixed stand could be explained by a positive interaction between effects of thinning and niche complementarity. We propose that thinning that maintains species diversity of mixed stands could help forest managers who are implementing ecosystem management to reconcile timber production objectives with biodiversity issues.     

Effects of the overstory on the diversity of the herb and shrub layers of Anatolian black pine forests

Understory plants are important components of forests because they are responsible for the majority of the vascular plant diversity of forest ecosystems. The richness and composition of understory communities are closely related to the tree layer diversity, structure and composition. The aim of this study was to examine the understory diversity of Anatolian black pine (Pinus nigra Arnold subsp. pallasiana (Lamb.) Holmboe)-dominated forests on the Kazda?? Mountains of West Turkey. To describe the overstory structure and composition in a numerically and quantitatively well-defined manner, cumulative abundance profiles (CAPs) of the tree species were used. The resemblance of the sampling plots was classified into five stand types assessing the CAP through the Fuzzy C-Means clustering method. A permutational multivariate analysis of variance (PERMANOVA) was performed to test the variance of the community ecological distance between the five stand types, and the results showed significant differences in these clusters. Many shade-tolerant plants were associated with the mixed stands of Anatolian black pine–Kazda?? fir. The composition of the herb and shrub layer could not be explained by the environmental variables but by differences in the overstory structure of the stands. Pure or nearly pure Anatolian Black pine stands were more diverse than mixed oak–Anatolian black pine and Kazda?? fir–Anatolian black pine stands. However, although dense and young pure Anatolian black pine stands had the most diverse plant species in the shrub layer, they were ranked third in terms of the herb layer diversity. The Anatolian black pine–Kazda?? fir mixed stands had the lowest herb and shrub layer diversity. These results allow us to comprehend the relationship between the overstory structure and composition, and the understory diversity. Understanding this relationship is important for the conservation of understory plant diversity in the management of forest ecosystems.