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1.
树木位置和胸径对人工林细根水平分布的影响   总被引:5,自引:2,他引:3  
通过研究福建三明莘口林场33年生格氏栲和杉木人工林细根生物量与树木位置和胸径大小的关系,探讨人工林细根水平分布特点。用土芯法(土钻内径6 .8cm,深10 0 cm)测定细根生物量,格氏栲和杉木人工林分别随机取土芯4 1个和4 0个,同时记录离取样点最近的第1棵、第2棵和第3棵树的距离和胸径。格氏栲和杉木人工林细根生物量平均值分别为3.2 6 6 t/ hm2和2 .0 4 8t/ hm2 ,变异系数分别达37.3%和4 2 .8% ,细根生物量均遵从正态分布(p<0 .0 5 )。格氏栲和杉木人工林细根生物量均与离取样点最近第1棵、第2棵树的距离有显著的负相关,且以与最近第1棵树距离的相关系数最大。格氏栲人工林细根生物量与最近第1棵树的胸径呈显著的正相关(p<0 .0 1) ,而与最近第2、第3棵树的胸径无关(p>0 .0 5 ) ;而杉木人工林细根生物量则与最近第1、第2和第3棵树的胸径均无显著相关(p>0 .0 5 )。逐步多元线性回归分析表明,离取样点最近第1棵树距离和胸径可解释格氏栲人工林细根生物量水平变异的4 1.0 % ,而离取样点最近第1、2棵树距离则可解释杉木人工林细根生物量水平变异的4 0 .6 %。由于人工林细根水平分布呈现特定模式,规则取样估计细根生物量将产生系统误差。  相似文献   

2.
格氏栲和杉木人工林地下碳分配   总被引:8,自引:2,他引:6  
通过对福建三明36年生的格氏栲人工林和杉木人工林林木地下C分配(TBCA)进行研究,结果表明,由分室累加法直接测定的格氏栲和杉木人工林的TBCA分别为8.426和4.040 t C.hm-2.-a 1。在格氏栲和杉木人工林TBCA组成中,根系净生产量和根系呼吸各约占50%;在根系年净生产量中,细根年净生产量和粗根年净生产量各约占75%和25%。而格氏栲和杉木人工林的细根年C归还量则均约占各自TBCA的1/3(分别为33%和36%)。在假设地下C库处于稳定状态时,由C平衡法计算的格氏栲和杉木人工林的TBCA(分别为6.039t C.hm-2.-a 1和2.987 t C.hm-2.-a 1)低于分室累加法,这与两种人工林地下C库尚未达到稳定状态有关。利用R a ich and N ade lhoffer全球模式方程推算的格氏栲和杉木人工林的TBCA(分别为9.771t C.hm-2.a-1和5.344 t C.hm-2.-a 1)则高于分室累加法,这与全球模式方程只是一种全球尺度规律有关。  相似文献   

3.
格氏栲天然林与人工林枯枝落叶层碳库及养分库   总被引:30,自引:4,他引:26  
通过对福建三明格氏栲天然林及在其采伐迹地上营造的 33年生格氏栲人工林和杉木人工林枯枝落叶层现存量与季节动态、C库及养分库的研究表明 ,格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层现存量分别为 8.99t· hm- 2 、7.5 6t· hm- 2 和 4 .81t· hm- 2 ;枯枝落叶层中叶占现存量的比例分别为 6 4 .96 %、6 1.38%和 38.0 5 % ,枝占比例分别为 31.5 9%、37.83%和 4 2 .6 2 %。格氏栲天然林与人工林枯枝落叶层现存量最大值均出现在春季 ,而杉木人工林枯枝落叶层现存量最大值出现在夏季。格氏栲天然林枯枝落叶层 C贮量为 4 .0 2 t· hm- 2 ,分别是格氏栲人工林和杉木人工林的 1.2 2倍和 1.77倍 ;格氏栲天然林和人工林枯枝落叶层 C库与杉木人工林的差异均达到显著水平 (P<0 .0 5 )。格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层养分贮量分别为 138.4 2 kg· hm- 2 、113.5 6 kg· hm- 2 和 72 .39kg· hm- 2 ;除 Mg外 ,格氏栲天然林枯枝落叶层中各种养分贮量均最高。与人工林相比 ,天然林枯枝落叶层现存量、C和养分贮量均最大。枯枝落叶层对林地长期生产力维持具有重要作用。  相似文献   

4.
通过对中亚热带格氏栲天然林(natural forest of Castanopsis kawakamii。约150年生)、格氏挎和杉木人工林(monoculture plantations of C.kawakamii and Cunninghamia lanceolata,33年生)凋落物数量与季节动态、养分归还及凋落叶分解与其质量的关系为期3a的研究表明。林分年均凋落量及叶所占比例分别为:格氏栲天然林11.01t/hm^1。59.70t/hm^2;格氏栲人工林9.54%。71.98%;杉木人工林5.47t/hm^2。58.29%。格氏栲天然林与人工林凋落量每年只出现1次峰值(4月份)。而杉木林的则出现3次(4或5月份、8月份和11月份)。除杉木林的Ca和格氏栲人工林的Mg年归还量最大外。N、P、K及养分总归还量均以格氏栲天然林的为最大。杉木人工林的最小。分解la后格氏栲天然林中格氏栲叶的干重损失最大(98.16%)。杉木叶的最小(60.78%)。C/N及木质素/N比值与凋落叶分解速率呈显著负相关。而N、水溶性化合物初始浓度与分解速率呈显著正相关。与针叶树人工林相比,天然林的凋落物数量大、养分归还量高、分解快。具有良好自我培肥地力的能力。因此。保护和扩大常绿阔叶林资源已成为南方林区实现森林可持续经营的重要措施之一。  相似文献   

5.
2010年11月-2011年12月, 研究了华西雨屏区31年生香樟人工林土壤表层(0~30 cm)细根生物量及碳储量.结果表明: 香樟人工林土壤0~30 cm层细根总生物量(活根+死根)和碳储量的平均值分别为1592.29 kg·hm-2和660.68 kg C·hm-2,其中活细根贡献率分别为91.1%和91.8%.随着土壤深度的增加,香樟1~5级活细根和死细根的生物量及碳储量均显著减少;随着根序等级的升高,香樟活细根生物量及碳储量显著增加.香樟细根总生物量及碳储量均在秋季最高、冬季最低,死细根生物量及碳储量为冬季最高、夏季最低;1级根和2级根生物量及碳储量均在夏季最高、冬季最低,而3~5级根则为秋季最高、冬季最低.土壤养分和水分的空间异质性是导致细根生物量和碳储量变化的主要原因.  相似文献   

6.
格氏栲天然林与人工林根系呼吸季节动态及影响因素   总被引:37,自引:5,他引:32  
通过用挖壕沟 静态碱吸收法对福建三明格氏栲天然林及33年生格氏栲和杉木人工林的根系呼吸进行为期2a定位研究。不同森林根系呼吸速率季节变化均呈单峰曲线,最大值出现在春末或夏初,最小值出现在冬季。1年中格氏栲天然林、格氏栲人工林和杉木人工林根系呼吸速率变化范围分别在157.76~480.40mgCO2/(m2·h)、53.03~339.45mgCO2/(m2·h)和16.66~228.02mgCO2/(m2·h)之间。在近似正常气候状况的2002年,不同森林根系呼吸主要受土壤温度影响(R2=0.52~0.72);而土壤温度和土壤湿度共同则可解释根系呼吸速率季节变化的81%~90%。在极端干旱的2003年,根系呼吸受土壤温度或湿度的影响较小,土壤温度和土壤湿度共同仅能解释根系呼吸变化的24%~60%,这与根系在持续干旱期间长期处于近休眠状态有关。根系呼吸对土壤温度和土壤湿度的敏感性大小顺序均为杉木人工林>格氏栲人工林>格氏栲天然林。格氏栲天然林根系呼吸占土壤呼吸比例(47.6%)均高于格氏栲和杉木人工林的(42.5%和40.2%),不同森林根系呼吸占土壤呼吸比例均以冬季最低,而以5月或6月最高。格氏栲天然林、格氏栲人工林和杉木人工林根系呼吸年通量分别为6.537、4.013和1.828tC/(m2·h)。  相似文献   

7.
水曲柳根系生物量、比根长和根长密度的分布格局   总被引:1,自引:1,他引:0  
采用连续钻取土芯法在生长季内对东北林业大学帽儿山实验林场17年生水曲柳人工林根系取样,研究水曲柳不同直径根系现存生物量、比根长和根长密度及垂直分布状况.结果表明,水曲柳人工林根系总生物量为1 637.6 g·m-2,其中活根生物量占85%,死根占15%.在活根生物量当中,粗根(直径5~30 mm)占的比例最高(69.95%),其次为活细根(直径<1 mm,13.53%),小根(1~2 mm)和中等直径的根(2~5 mm)比例较小(分别为7.21%和9.31%).直径<1 mm活细根的比根长为32.20 m·g-1,直径5~30 mm粗根的比根长为0.08 m·g-1.单位面积上活根的总长度为6 602.54 m·m-2,其中直径<1 mm的细根占92.43%,其它直径等级则不到活根总长度的8%.直径<1 mm的细根生物量与根长密度具显著线性关系(R2=0.923),但与比根长无显著相关关系(R2=0.134).  相似文献   

8.
中国亚热带森林转换对土壤呼吸动态及通量的影响   总被引:43,自引:6,他引:37  
通过用静态碱吸收法对中国亚热带福建三明格氏栲自然保护区内的格氏栲天然林和33年生的格氏栲人工林及杉木人工林的土壤呼吸进行为期2a的定位研究,结果表明,3种森林土壤呼吸速率季节变化均呈单峰曲线,最大值出现在5月至6月份,最小值出现在12月至翌年1月份。格氏栲天然林、格氏栲人工林和杉木人工林土壤呼吸速率一年中变化范围分别在403.47~1001.12mgCO2m-2h-1、193.89~697.86mgCO2m-2h-1和75.97~368.98mgCO2m-2h-1之间。2002年土壤呼吸速率主要受土壤温度影响,但在极端干旱的2003年则主要受土壤湿度的影响。双因素关系模型(R=aebTWc)拟合结果优于仅考虑土壤温度或土壤湿度的单因素关系模型,土壤温度和土壤湿度共同解释不同年份不同森林土壤呼吸速率季节变化的80%~96%。杉木林土壤呼吸对气候变化敏感性高于格氏栲天然林和人工林。格氏栲天然林、格氏栲人工林和杉木人工林土壤呼吸年通量分别为13.742、9.439和4.543tC·hm-2·a-1,前者分别约是后二者的1.5倍和3.0倍。森林转换对土壤呼吸通量的影响可能与枯落物数量和质量、根系呼吸、土壤有机质数量和质量的变化有关。  相似文献   

9.
亚热带不同林分土壤矿质氮库及氮矿化速率的季节动态   总被引:4,自引:0,他引:4  
以亚热带地区天然林、格氏栲人工林和杉木人工林为对象,采取PVC管原位培养连续取样法,对不同林分土壤净氨化速率、净硝化速率及净氮矿化速率进行为期一年(2014年9月—2015年8月)的研究,分析林分类型和季节动态对土壤矿质氮库和净氮矿化速率的影响.结果表明: 硝态氮是该地区土壤矿质氮库的主要存在形式,天然林和杉木人工林土壤硝态氮含量分别占总土壤矿质氮库的55.1%~87.5%和56.1%~79.1%,林分间土壤铵态氮含量差异不显著,硝态氮含量差异显著,其中格氏栲人工林土壤硝态氮含量显著低于天然林和杉木人工林.土壤硝态氮库和矿质氮库在不同月份间差异显著,在植物非生长季节(10月至次年2月)较大,在植物生长季节(3—9月)较小.各林分全年土壤净硝化速率均较低,净氨化速率是净氮矿化速率的主要存在形式,林分类型对土壤净氨化速率有显著影响,其中杉木人工林显著低于天然林和格氏栲人工林.月份对土壤净氨化速率有显著影响,各林分土壤净氨化速率变化规律不一致,但均在11月和2月达到一年中的最低值.重复测量方差分析显示,林分类型和季节动态对土壤矿质氮库及氮矿化速率均有显著影响.温度和水分是影响土壤矿质库及氮矿化速率的重要因素,凋落物对土壤氮矿化速率的影响主要是通过质量控制而非数量控制.  相似文献   

10.
拉萨河谷杨树人工林细根的生产力及其周转   总被引:6,自引:0,他引:6  
通过土钻取样和分解袋法对拉萨河谷杨树人工林细根的生长和周转进行了测定.结果表明,在该地区杨树人工林生态系统中,约80%的细根集中分布在0~30cm土壤表层中;接近树木一侧的活(死)细根生物量均高于外侧,但二者未达到显著的差异;在生长季期间,活细根生物量平均为2.576 t · hm-2,死细根生物量平均为1.566 t · hm-2,生长高峰出现在生长季初期.经估算,拉萨河谷杨树人工林细根年生长量为3.030 t · hm-2,年周转率为1.18次;但受高原低温的影响,细根分解缓慢,分解系数k平均为0.0007~0.0008.细根的这种生长特征是杨树对高原地区短暂生长季节和雨热同季气候条件的一种适应性表现.  相似文献   

11.
Plantation forests have been expanding in many tropical and subtropical environments. Howerver, even when they replace less wildlife friendly land uses such as pastures and annual crops, the biodiversity levels of pristine natural habitats often have not been recovered. Here we addressed how the landscape context of plantation forests located in South-eastern Brazil affects species richness and community resilience of medium and large size mammals. The area covered by native habitat fragments surrounding plantation forests is positively related to functional richness, including the presence of species more vulnerable to extinction in fragmented landscapes. In addition, the degree of aggregation of plantation forest stands is negatively related to more vulnerable species. No primates were recorded in our seven plantation forest sites (ranging from 272 to 24,921 ha), even when they were seen in native habitat fragments adjacent to commercial tree stands. Two invasive species (Sus scrofa and Lepus capensis) were recorded in four plantation forest sites. The impoverishment of fauna in plantation forests is due to two factors. First, plantation forests generally are structurally simplified habitats when compared to highly diverse tropical forests. Secondly, the isolation from habitat fragments which act as source of individuals in the landscape precludes the establishment of individual in plantation forest. We also highlighted the management practices to improve the complexity of vegetation in commercial tree stands should be taken cautiously, insofar as reduced productivity per area entails a greater demand for land. Thus, an alternative would be intensify the management of the commercial tree stands for wood production together with the restoration of adjacent areas set aside to conservation and native habitat fragments protection.  相似文献   

12.
We studied the pattern of bird species richness in native and exotic forest patches in Hungary. We hypothesized that species-area relationship will depend on forest naturalness, and on the habitat specialization of bird species. Therefore, we expected strong species-area relationship in native forest patches and forest bird species, and weaker relationship in exotic forest patches containing generalist species. We censused breeding passerine bird communities three times in 13 forest patches with only native tree species, and 14 with only exotic trees in Eastern Hungary in 2003. Although most bird species (92%) of the total of 41 species occurred in both exotic and native forests, the species-area relationship was significant for forest specialist, but not for generalist species in the native forests. No relationship between bird species and area was found for either species group in the forest with exotic tree species. The comparison of native versus exotic forest patches of similar sizes revealed that only large (>100 ha) native forests harbor higher bird species richness than exotic forests for the forest specialist bird species. There is no difference between small and medium forest patches and in richness of generalist species. Thus, the species-area relationship may diminish in archipelago of exotic habitat patches and/or for habitat generalist species; this result supports the warning that the extension of exotic habitats have been significantly contributing to the decline of natural community patterns.  相似文献   

13.
Non-native trees may have significant impacts on the carbon sink capacity of forested lands. However, large-scale patterns of the relative capacity of native and non-native forests to uptake and store carbon remain poorly described in the literature, and this information is urgently needed to support management decisions. In this study, we analyzed 17,065 plots from the Spanish Forest Inventory (covering c. 30 years) to quantify carbon storage and sequestration of natural forests and plantations of native and non-native trees under contrasting climate types, while controlling for the effects of environmental factors (forest structure, climate, soil, topography, and management). We found that forest origin (non-native vs. native) highly influenced carbon storage and sequestration, but such effect was dependent on climate. Carbon storage was greater in non-native than in native forests in both wet and dry climates. Non-native forests also had greater carbon sequestration than native ones in the wet climate, due to higher carbon gains by tree growth. However, in the dry climate, native forests had greater carbon gains by tree ingrowth and lower carbon loss by tree mortality than non-native ones. Furthermore, forest type (classified by the dominant species) and natural forests versus tree plantations were important determinants of carbon storage and sequestration. Native and non-native Pinus spp. forests had low carbon storage, whereas non-native Eucalyptus spp. forests and native Quercus spp., Fagus sylvatica, and Eurosiberian mixed forests (especially not planted ones) had high carbon storage. Carbon sequestration was greatest in Eucalyptus globulus, Quercus ilex, and Pinus pinaster forests. Overall, our findings suggest that the relative capacity of native and non-native forests to uptake and store carbon depends on climate, and that the superiority of non-native forests over native ones in terms of carbon sequestration declines as the abiotic filters become stronger (i.e., lower water availability and higher climate seasonality).  相似文献   

14.
Shaded coffee has been highlighted for its potential to conserve biodiversity, and thus perhaps also a diversity of natural enemies that could control pest organisms. In southwestern Ethiopia, coffee is grown in shade both in contiguous forests and in forest patches with native trees surrounded by open fields. We hypothesized that coffee grown in contiguous forests, which is the natural habitat for coffee (Coffea arabica) and its interacting organisms, would have less pest damage due to high protection by natural enemies. We surveyed pests on coffee plants in plots within contiguous forests (10 sites) and in forest patches (21 sites). In general, the variation in number of damaged or attacked leaves by individual insect or fungal pests was larger between plants than between plots, which suggests that very local conditions or processes are important. The spatial signals were generally weak. Coffee rust and coffee blotch miner tended to have lower infestation rates in accordance with our hypothesis, while fruit flies in ripe berries were more abundant in forest patches closer to contiguous forest. Based on interviews, olive baboons showed a clear dependency on contiguous forest habitat and were regarded as a problem only in contiguous forests and forest patches close to contiguous forests. In conclusion, we found no support for a generally stronger top‐down control on coffee pests in sites within, or with connectivity to, contiguous moist afromontane forests in the native range of coffee.  相似文献   

15.
Although the importance of natural habitats to pollinator diversity is widely recognized, the value of forests to pollinating insects has been largely overlooked in many parts of the world. In this review, we (i) establish the importance of forests to global pollinator diversity, (ii) explore the relationship between forest cover and pollinator diversity in mixed-use landscapes, and (iii) highlight the contributions of forest-associated pollinators to pollination in adjacent crops. The literature shows unambiguously that native forests support a large number of forest-dependent species and are thus critically important to global pollinator diversity. Many pollinator taxa require or benefit greatly from resources that are restricted to forests, such as floral resources provided by forest plants (including wind-pollinated trees), dead wood for nesting, tree resins, and various non-floral sugar sources (e.g. honeydew). Although landscape-scale studies generally support the conclusion that forests enhance pollinator diversity, findings are often complicated by spatial scale, focal taxa, landscape context, temporal context, forest type, disturbance history, and external stressors. While some forest loss can be beneficial to pollinators by enhancing habitat complementarity, too much can result in the near-elimination of forest-associated species. There is strong evidence from studies of multiple crop types that forest cover can substantially increase yields in adjacent habitats, at least within the foraging ranges of the pollinators involved. The literature also suggests that forests may have enhanced importance to pollinators in the future given their role in mitigating the negative effects of pesticides and climate change. Many questions remain about the amount and configuration of forest cover required to promote the diversity of forest-associated pollinators and their services within forests and in neighbouring habitats. However, it is clear from the current body of knowledge that any effort to preserve native woody habitats, including the protection of individual trees, will benefit pollinating insects and help maintain the critical services they provide.  相似文献   

16.
The riverine forests of the northern city of Edmonton, Alberta, Canada display strong resilience to disturbance and are similar in species composition to southern boreal mixedwood forest types. This study addressed questions such as, how easily do exotic species become established in urban boreal forests (species invasiveness) and do urban boreal forest structural characteristics such as, native species richness, abundance, and vertical vegetation layers, confer resistance to exotic species establishment and spread (community invasibility)? Eighty-four forest stands were sampled and species composition and mean percent cover analyzed using ordination methods. Results showed that exotic tree/shrub types were of the most concern for invasion to urban boreal forests and that exotic species type, native habitat and propagule supply may be good indicators of invasive potential. Native forest structure appeared to confer a level of resistance to exotic species and medium to high disturbance intensity was associated with exotic species growth and spread without a corresponding loss in native species richness. Results provided large-scale evidence that diverse communities are less vulnerable to exotic species invasion, and that intermediate disturbance intensity supports species coexistence. From a management perspective, the retention of native species and native forest structure in urban forests is favored to minimize the impact of exotic species introductions, protect natural succession patterns, and minimize the spread of exotic species.  相似文献   

17.
Abstract Coarse woody debris (CWD) is the standing and fallen dead wood in a forest and serves an important role in ecosystem functioning. There have been several studies that include estimates of CWD in Australian forests but little synthesis of these results. This paper presents findings from a literature review of CWD and fine litter quantities. Estimates of forest‐floor CWD, snags and litter from the literature are presented for woodland, rainforest, open forest and tall open forest, pine plantation and native hardwood plantation. Mean mass of forest floor CWD in Australian native forests ranged from 19 t ha?1 in woodland to 134 t ha?1 in tall open forest. These values were generally within the range of those observed for similar ecosystems in other parts of the world. Quantities in tall open forests were found to be considerably higher than those observed for hardwood forests in North America, and more similar to the amounts reported for coniferous forests with large sized trees on the west coast of the USA and Canada. Mean proportion of total above‐ground biomass as forest floor CWD was approximately 18% in open forests, 16% in tall open forests, 13% in rainforests, and 4% in eucalypt plantations. CWD can be high in exotic pine plantations when there are considerable quantities of residue from previous native forest stands. Mean snag biomass in Australian forests was generally lower than the US mean for snags in conifer forests and higher than hardwood forest. These results are of value for studies of carbon and nutrient stocks and dynamics, habitat values and fire hazards.  相似文献   

18.
Forestry management worldwide has become increasingly effective at obtaining high timber yields from productive forests. In New Zealand, a focus on improving an increasingly successful and largely Pinus radiata plantation forestry model over the last 150 years has resulted in some of the most productive timber forests in the temperate zone. In contrast to this success, the full range of forested landscapes across New Zealand, including native forests, are impacted by an array of pressures from introduced pests, diseases, and a changing climate, presenting a collective risk of losses in biological, social and economic value. As the national government policies incentivise reforestation and afforestation, the social acceptability of some forms of newly planted forests is also being challenged. Here, we review relevant literature in the area of integrated forest landscape management to optimise forests as nature-based solutions, presenting ‘transitional forestry’ as a model design and management paradigm appropriate to a range of forest types, where forest purpose is placed at the heart of decision making. We use New Zealand as a case study region, describing how this purpose-led transitional forestry model can benefit a cross section of forest types, from industrialised forest plantations to dedicated conservation forests and a range of multiple-purpose forests in between. Transitional forestry is an ongoing multi-decade process of change from current ‘business-as-usual’ forest management to future systems of forest management, embedded across a continuum of forest types. This holistic framework incorporates elements to enhance efficiencies of timber production, improve overall forest landscape resilience, and reduce some potential negative environmental impacts of commercial plantation forestry, while allowing the ecosystem functioning of commercial and non-commercial forests to be maximised, with increased public and biodiversity conservation value. Implementation of transitional forestry addresses tensions that arise between meeting climate mitigation targets and improving biodiversity criteria through afforestation, alongside increasing demand for forest biomass feedstocks to meet the demands of near-term bioenergy and bioeconomy goals. As ambitious government international targets are set for reforestation and afforestation using both native and exotic species, there is an increasing opportunity to make such transitions via integrated thinking that optimises forest values across a continuum of forest types, while embracing the diversity of ways in which such targets can be reached.  相似文献   

19.
Plantations of fast-growing hybrid trees, such as hybrid poplars and hybrid larch, are increasingly used for wood and timber production, but they are also believed to impair forest biodiversity. Most studies that have assessed how such plantations may alter the diversity and composition of understorey plants were established in agricultural landscapes or have compared tree plantations with old-growth natural forests. Moreover, many important aspects of biodiversity have been overlooked in previous studies, such as functional and beta-diversity. Here, we present results from a study that was aimed at quantifying alpha- and beta-diversity of understorey plant species and functional groups in hybrid poplar (9–10 years) and hybrid larch plantations (16 years) located within a forested landscape of Quebec, Canada. These hybrid plantations were compared to naturally regenerated secondary forests and to native plantations of black spruce of the same origin (clear cut) and similar age. Our results indicate that fast-growing hybrid plantations do not present lower taxonomic and functional alpha-biodiversity indices, but may harbour more diverse communities, in part through the introduction of plant species that are associated with open habitats. We provide further evidence that planted forests may be as heterogeneous as naturally regenerated forests in terms of understorey plant composition. Plant species and functional composition differed slightly between stand types (naturally regenerated forests, native and fast-growing hybrid plantations), with plantations offering a greater potential for colonisation by ruderal species, while being detrimental to species of closed forest habitats. Lastly, plantations of fast-growing hybrids do not induce greater changes in understorey vegetation relative to native plantations of black spruce, at least during the first stand rotation.  相似文献   

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