Diversity of secondary woody species in relation to species richness and cover of dominant trees in thermophilous deciduous forests

One of the prominent compositional features of thermophilous deciduous forests of southern Europe is their richness in secondary woody species (AWS). To date, no studies have focused on the diversity and contribution to the ecosystem functions and socio-economic benefits provided by these species. Here, we first characterized species richness and diversity for three main functional groups of AWS, sporadic trees, shrubs and vines, in 53 representative stands of central Italy. Secondly, we explored variations in AWS diversity and composition along a four-level gradient of species richness of dominant trees under comparable site conditions. The 40 AWS taxa recorded showed a remarkable taxonomic singularity at both the genus and the family rank. Dominant tree species richness had no significant effect on AWS species richness and composition, while Shannon diversity of AWS, especially shrubs, was associated with cover of the dominant trees. Each AWS possessed, on average, ca. five ability traits over a total of 13 considered that contributed to important ecosystem functions or expected socio-economic benefits such as wood and food production, conservation of genetic resources (wild crop relatives) and ornamentals. This highlights the key role of AWS, and in particular of sporadic trees, for enhancing multifunctionality of thermophilous deciduous forests.     

Litter production and decomposition dynamics in moist deciduous forests of the Western Ghats in Peninsular India

A field study was conducted in the moist deciduous forests of the Western Ghats (India) to test the following three hypotheses: (1) Litter production in tropical forests is a function of the floristic composition, density, basal area and disturbance intensity; (2) Decay rate constants of tropical species is an inverse function of the initial lignin/nitrogen ratio; (3) Decomposition rates in tropical forests are faster than temperate forests.

Litter fall was estimated by installing 63 litter traps in the moist deciduous forests of Thrissur Forest Division in the Western Ghats at three sites. Litter fall followed a monomodal distribution pattern with a distinct peak during the dry period from November–December to March–April.Dillenia pentagyna, Grewia tiliaefolia, Macrosolen spp.,Xylia xylocarpa, Terminalia spp.,Lagerstroemia lanceolata, Cleistanthus collinus, Bridelia retusa, andHelicteres isora were the principal litter producing species at these sites. The annual litter fall ranged from 12.18 to 14.43 t ha⁻¹. Structural attributes of vegetation such as floristic composition, basal area, density and disturbance intensity did not directly influence litter fall rates.

Leaf litter decay rates for six dominant tree species were assessed following the standard litter bag technique. One hundred and eight litter bags per species containing 20 g samples were installed in the forest floor litter layer at the same three sites selected for the litter fall quantification exercise. The residual litter mass decreased linearly with time for all species. In general, less disturbed sites and species adapted to higher nitrogen availabilities exhibited relatively higher decay rate coefficients (k). The rapid organic matter turnover observed in comparison with published temperate forest litter decay rates confirms that tropical moist deciduous forest species are characterised by faster decomposition rates.

Mean concentrations of N, P and K in the litter were profoundly variable amongst the dominant species. Initial nitrogen content of the leaf litter varied from 0.65 to 1.6%, phosphorus from 0.034 to 0.077% and potassium from 0.25 to 0.62%.C. collinus, an understorey shrub consistently recorded the lowest litter concentrations for all nutrients. The overriding pattern is one of higher nutrient levels in the overstorey leaf litter and lower concentrations in the understorey litter. Furthermore, as decomposition proceeded, the nitrogen concentration of the residual biomass increased.     

Tree species diversity and stand structure along major community types in lowland primary and secondary moist deciduous forests in Tripura, Northeast India

Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura.Overall 10,957 individual trees belonging to 46 family,103 genera and 144 species were counted at ≥30 cm DBH(diameter at breast height) using 28 permanent belt transects with a size of 1 ha(10 m × 1000 m).Four different tree communities were identified.The primary forests was dominated by Shorea robusta(mean density 464.77 trees ha-1,105 species) and Schima wallichii(336.25 trees ha-1,82 species),while the secondary forests was dominated by Tectona grandis(333.88 trees ha-1,105 species) and Hevea brasiliensis(299.67 trees ha-1,82 species).Overall mean basal area in this study was 18.01m 2 ·ha-1 ;the maximum value was recorded in primary Shorea forest(26.21 m 2 ·ha-1).Mean density and diversity indices were differed significantly within four different communities.No significant differences were observed in number of species,genera,family and tree basal cover area.Significant relationships were found between the species richness and different tree population groups across the communities.Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumulation of native oligarchic small tree species.Seventeen species were recorded with <2 individuals of which Saraca asoka(Roxb.) de Wilde and Entada phaseoloides(L.) Merr.etc.extensively used in local ethno-medicinal formulations.The present S.robusta Gaertn dominated forest was recorded richer(105 species) than other reported studies.Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests.Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur.The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T.grandis L.dominated community.     

林隙微生境及更新研究进展

系统评述了国内外关于林隙干扰及更新的最新研究进展.林隙是一种经常发生的小规模干扰,是森林群落时空格局变化的驱动力.不同的林隙干扰状况导致了林隙内光照的差异,进一步造成林隙内温度、湿度、土壤理化性质的变化,形成了微生境的时空异质性.林隙干扰通过改变微生境而对幼苗的出土、存活、定居和生长产生重要影响.林隙内种子库的物种丰富度变化很大,是幼苗分布格局的重要影响因子.更新幼苗的存活率和生长量受林隙大小及幼苗在林隙中位置的影响.指出了这一领域今后的研究方向.     

Effect of recurrent fires on soil nutrient dynamics in a tropical dry deciduous forest of Western Ghats,India

The role of forest fires in the soil dynamics and global carbon cycle has not been comprehensively studied in tropical forests as the effects of fire on tropical forest soils can be extremely variable. This study was aimed to understand how repeated fires affect physical and chemical properties of soil in a tropical dry deciduous forest and alter soil fertility and health. The study was carried out in the dry deciduous forest of Mudumalai Tiger Reserve. Soil samples were collected from unburned (B0) to six-time burned (B6) plots. Samples were collected from each plot from three different depths viz. 0–10 (Top), 10–20 (Middle), and 20–30 cm (Bottom) and analyzed for soil physical and chemical properties. Soil pH, EC, WHC decreased with increasing fire frequencies while bulk density increased. Organic Carbon, Total N, and available P decreased with increasing fire frequencies whereas extractable K initially increased but decreased with the very high frequency of fires. NO₃^?N slightly decreased with high fire frequencies but NH₄^?N decreased significantly with increasing fire frequency. These results provide a new insight regarding the influence of repeated fires on soil that will be valuable to understand the effect of fire on the recovery of soils and nutrient dynamics.     

Successional patterns and gap phase dynamics of a humid tropical forest of the Western Ghats of Kerala, India: ground vegetation, biomass, productivity and nutrient cycling

The population dynamics of the ground vegetation and its energetics such as biomass accumulation and net primary productivity, and the nutrient cycling patterns in the humid tropical forest of the Western Ghats in India are largely determined by gap age and by whether gaps are formed naturally or through selection felling. Responses of plant categories such as herbs, shrubs, tree seedlings and saplings also vary depending upon gap type and age. An exotic species such as Chromolaena odorata occurred only in selection-felled gaps ((9 ± 3)−(49 ± 4) individuals (100 m)⁻²). Nilgirianthus ciliatus, a dominant shrub, plays a key role in the gaps in determining population dynamics of others. The net primary productivity of the ground vegetation, which is about 31.17 ± 4.26 kg (100 m)⁻² year⁻¹ in an undisturbed site, increased a year after gap formation to 102.82 ± 6.46 kg (100 m)⁻² year⁻¹ in natural gaps and to 71.82 ± 2.36 kg (100 m)⁻² year⁻¹ in selection-felled gaps. Five years after gap formation, net primary productivity of the ground vegetation declined considerably, this being related to decline in fast-growing shrub and secondary tree species in the vegetation and gap closure. A similar trend was also recorded for the rates of nutrient uptake and nutrient accumulation in the vegetation.

In natural gaps the soil nutrient level increased gradually with gap age. This could be attributed to slow release of nutrients from the fallen trunks and nutrient storage in the rapidly recovering vegetation. In contrast, in selection-felled gaps, the quantities of soil nutrients such as nitrogen, phosphorus and magnesium were higher in 1-year-old gaps than in undisturbed sites, owing to the release of these nutrients from leaf litter and wood debris which were deposited in larger quantities within the gap itself, and owing to sparse ground vegetation resulting from the greater disturbance of the soil, in the first 1 or 2 years. The fractional annual turnover rates of elements of the ground vegetation and the soil were higher in 1-year-old gaps and declined with gap age. The significance of these results for forest management is discussed.     

热带季节雨林林窗不同热力作用面的热力特征

利用热带季节雨林林窗区域小气候要素的观测资料,探讨了昼间林窗区域不同热力作用面的热力特征.在西双版纳雾凉季,热带季节雨林与次生林相似,其林窗边缘壁面具有不可忽视的热力作用,是林窗区域除林冠面、林窗地表面和林内地表面之外的新的热力作用面.由于林窗边缘树木高度的影响,其东侧、北侧林缘壁面热力效应最大区域出现位置高于次生林林窗,而热力效应强度小于次生林林窗.其结果可为进一步研究林窗小气候形成机制提供研究基础,为研究林窗更新及生物多样性影响提供科学参考.     

Wildland fires and moist deciduous forests of Chhattisgarh,India: divergent component assessment

We studied moist deciduous forests of Chhattisgarh, India （1） to assess the effect of four levels of historic wildland fire frequency （high, medium, low, and no-fire） on regeneration of seedlings in fire affected areas during pre and post-fire seasons, （2） to evaluate vegetation struc- ture and diversity by layer in the four fire frequency zones, （3） to evalu- ate the impact of fire frequency on the structure of economically impor- tant tree species of the region, and （4） to quantify fuel loads by fire fre- quency level. We classified fire-affected areas into high, medium, low, and no-fire frequency classes based on government records. Tree species were unevenly distributed across fire frequency categories. Shrub density was maximum in zones of high fire frequency and minimum in low- frequency and no-fire zones. Lower tree density after fires indicated that regeneration of seedlings was reduced by fire. The population structure in the high-frequency zone was comprised of seedlings of size class （A） and saplings of size class （B）, represented by Diospyros melanoxylon, Dalbergia sissoo, Shorea robusta and Tectona grandis. Younger and older trees were more abundant for Tectona grandis and Dalbargia sis- soo after fire, whereas intermediate-aged trees were more abundant pre- fire, indicating that the latter age-class was thinned by the catastrophic effect of fire. The major contributing components of fuel load included duff litter and small woody branches and twigs on the forest floor. Total fuel load on the forest floor ranged from 2.2 to 3.38 Mg/ha. The netchange in fuel load was positive in high- and medium-frequency fire zones and negative under low- and no-fire zones. Repeated fires, how- ever, slowly reduced stand stability. An ecological approach is needed for fire management to restore the no-fire spatial and temporal structure of moist deciduous forests, their species composition and fuel loads. The management approach should incorporate participatory forest manage- ment. Use of c     

Anthropogenic disturbances and status of forest and wildlife in the dry deciduous forests of Chhattisgarh state in India

The advent of modern forces and the changes in socioeconomic patterns of forest dwellers have increased the pressures on the forests. In order to mitigate such pressures and also to protect the forests and wildlife the model of protected areas networks has shifted and enhanced such pressures in the unprotected natural forests due to several reasons. Being a low profile category of protected status and continuous human settlements, the present study highlights the case of dry deciduous forests of Sarguja district of Chhattisgarh state of India. The major objectives of this study were to quantify the status of forests and wildlife and also to determine the extent of anthropogenic disturbances faced by the dry deciduous forests of central India. Transect and silent drive count methods were used for sampling wildlife and quadrat method was used for sampling vegetation. Besides, the local uses of various forest produces were also studied in view of understanding the people dependency on forests. The forest vegetation, in the study area, was pre-dominated by Shorea robusta, which had Madhuca indica, Diospyrus melanoxylon and Buchnania lanzan as the major companion species. The forest had either the high girth class mature tree species or the saplings. The low vegetation cover and density were due to the high anthropogenic pressures mainly in the form of heavy livestock grazing and collection of ethnobotanically important species. The study though reveals that the area is not rich in wildlife and the forest is fragmented, the area still supports some important species, which include many rare and endangered plants and animals. The findings of this study have been discussed in view of the management and conservation of the forest and wildlife in the dry deciduous forests.     

我国天然云冷杉针阔混交林更新研究进展*

天然云冷杉针阔混交林是我国的主要森林类型之一 ,在国民用材中占有相当大的比重。天然更新对森林群落的重构起着至关重要的作用。采伐是影响森林更新的主要人为干扰因素之一。对天然云冷杉针阔混交林适宜采用择伐 ,不适宜采用皆伐。择伐强度在 3 0 %以下有利于天然更新。林隙中更新树种的种类和数量通常多于林冠下 ,林隙具有较高的物种多样性指数。     

Effect of abiotic factors on understory community structures in moist deciduous forests of northern India

Understory vegetation controls, in a significant way, the regeneration of overstory trees, carbon sequestration and nutrient retention in tropical forests. Development and organization of understory vegetation depend 3n climate, edaphic and biotic factors which are not well correlated with plant community structures. This study aimed to ~xplore the relationships between understory vegetation and abiotic factors in natural and planted forest ecosystems. A non-metric multidimensional scaling （NMS） ordination technique was applied to represent forest understory vegetation among five forest communities, i.e., a dry miscellaneous forest （DMF）, a sal mixed forest （SMF）, a teak plantation （TP）, a low-land miscellaneous forest （LMF） and a savanna area （SAV） of the Katerniaghat Wildlife Sanctuary, located in northern India. Microclimatic variables, such as photosynthetically active radiation （PAR）, air temperature （AT）, soil Lemperature （ST）, ambient atmospheric CO2 concentration, absolute air humidity （AH）, physical and chemical soil ~roperties as well as biological properties were measured. Understory species were assessed via 100 random quadrats （5 m x 5 m） in each of the five forests in which a total of 75 species were recorded encompassing 67 genera from 37 families, consisting of 32 shrubs and 43 plant saplings. DMF was the most dense forest with 34,068 understory individuals per ha of different species, whereas the lowest understory population （13,900 per ha） was observed in the savanna. Ordination and correlation revealed that microclimate factors are most important in their effect compared to ~daphic factors, on the development of understory vegetation in the various forest communities in the north of India.     

Soil quality assessment across different stands in tropical moist deciduous forests of Nagaland,India

To analyze the relationship between the management of three forest stand plantations and soil quality in the Dimapur district of the Northeastern Himalayan region,India,three forest soil profiles,covered by different species stands,at three depths were tested for 13 physical and chemical variables.Only four of these variables(electric conductivity,bulk density exchangeable Mg and available P)were included in a minimum data set,after using a varimax rotation algorithm in a principal component analysis,and subsequently used to calculate a soil quality index(SQI).Results showed higher SQIs in the surface layers(0–20 cm depth)than in the deeper ones.Average weighed SQI varied significantly(P<0.05)through the three considered forest sites,with the lowest value at site FS3.These findings reveal that the approach used here is suitable for preliminary screening of the impact of a forestry species on soil,to aid in species selection and improve soil health for afforestation and reforestation projects.     

光热和水分条件对石灰岩山地侧柏人工林更新的影响

侧柏(Platycladus orientalis)是我国荒山造林、水土保持和涵养水源的重要常绿树种之一。它适应环境的能力强,栽培范围广,常被栽植于我国的石灰岩山地上。耐干旱瘠薄是公认的侧柏生态学特性之一,但是,侧柏幼苗和幼树的更新和生长受山地环境影响较大。通过热红外成像法移动观测山体光热能量的分配特征,利用SketchUP软件三维阴影分析的功能进行林窗日照和遮阴分布的计算机模拟,以及在山东省侧柏主要栽培区对山地林窗幼苗进行实地调查研究,结果表明:侧柏苗适合栽培在湿润而光照充足的立地上。山地阴坡和阳坡、山谷和山脊的光照和湿度的差异导致侧柏幼苗更新的变化,以至于一边因密度过大而出现严重的种内竞争,另一边因幼苗更新不畅而常出现林窗和空地。因此,需要通过适度的人工抚育和管理来解决该问题,以便在我国北方地区建立起稳定和完善的侧柏森林生态系统。     

Characteristics and dynamics of sandy natural forests in sandy forest-steppe ecotone in the northern area of China

l "trod notionViolent human disturbance results in global landscape and vegetation fragmentation, including thepolar landscape and alpine vegetation (Cox, 1993).In modern world, environment and development aretWo important problems, which have a direct effecton the destiny of human and the earth. Forestry,which undertakes double missions that are to optimize the environment and promote the development,is the crux to realize the unity of environment anddevelopment (Liu 1985).China is a develop…     

Regeneration characteristics of gaps and their effect on Abies fargesii forests in the Shennongjia National Nature Reserve, China

Abies fargesii is an evergreen tree species of the Pinaceae family, one of the most important cultivated timber species,     

海南岛霸王岭热带山地雨林林隙更新生态位的研究

通过对海南岛霸王岭热带山地雨林林隙更新生态位的研究表明：同一树种在不同大小和年龄级林隙内的优势度不同，不同树种在同一大小和年龄级林隙内的优势度不同。根据树种在不同大小级林隙内的生态位宽度的变化，可分为生态位幅度宽、中等、较小和狭小4类；根据树种在不同年龄级林隙内的生态位宽度的变化，可分为对林隙时间生态资源利用充分、利用较充分、利用不充分和利用很少的4类树种。不同的树种或树种组对不同大小和年龄阶段林隙生态资源利用的不一致性，表明热带山地雨林中不同树种的林隙大小级生态位和林隙时间段生态位是相对分离的。分析表明，海南岛热带山地雨林中有很大一部分树种是属于低密度、狭生态位的树种。从物种多样性的角度来看，大量低密度、狭生态位树种的存在表明热带山地雨林是一种较为脆弱的生态系统类型。     

兴安落叶松老龄林分幼苗天然更新及微生境特点

对落叶松老龄林幼苗天然更新及微生境研究采用样线法，沿样线设置样方，调查样方内幼苗数、测定环境变量。结果表明，原始老龄林各环境变量中地表层的作用最突出，光照的作用最小，灌木层居中。一般，枯落物、根系盘结层和苔藓的作用较大，其中枯落物对苔藓的发育有抑制作用。抑制兴安落叶松更新的主要因素：在丛桦落叶松林中主要是草本植物、赤杨落叶松林为苔藓厚度、杜香落叶松林为苔藓厚度和根系盘结层厚度。     

Regeneration and survival of tree seedlings and sprouts in tropical deciduous and sub-tropical forests of Meghalaya,India

Species composition, regeneration status and survival of seedlings and sprouts of tree species were studied in tropical and subtropical forests of Meghalaya State in northeast India. The subtropical humid semi-evergreen forests at Upper Shillong and Mawphlang are dominated by Manglietia insignis, Pinus kesiya, Quercus dealbata, Q. griffithii, Rhododendron arboreum, Schima khasiana and Prunus undulata whereas the tropical deciduous forest lying at lower altitude (Burnihat) is dominated by Artocarpus chaplasa, Duabanga sonneratoides and Shorea robusta. The species composition of the tree community at the periphery is different from that of the forest stand at the centre. In the forests at Upper Shillong and Burnihat 40% of the tree species regenerated through both seedlings and sprouts, whereas the percentage of such trees in the undisturbed forest at Mawphlang was only about 22%. Survival of seedlings and sprouts was higher at the forest periphery than under the dense canopy, signifying the role of light in forest regeneration. Although the seedling mortality occurred throughout the year, it was particularly high during winter season due to prevailing low temperature and high soil moisture stress. The sprouts, however, were less susceptible to adverse environmental conditions.     

松华坝水库云南松林隙天然更新研究

对昆明地区松华坝水库库区天然云南松林隙更新情况通进行调查,分析了坡位、林隙面积大小等因子对林隙更新的影响．结果表明,坡中部林隙幼树天然更新情况较下部和上部好;当林隙面积小于200m^2时更新情况较差,在400～600m^2时更新情况最好;林隙中部更新情况最好,边缘次之,林隙外（林冠下）最差．     

Regeneration dynamics of dominant tree species along an altitudinal gradient in moist temperate valley slopes of the Garhwal Himalaya

The present study was undertaken in moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to understand the regeneration dynamics of the dominant tree species along an altitudinal gradient in naturally regenerating, restricted access forest. The overall regeneration status was fairly high in the study area. Most of the native canopy and undercanopy dominants had frequent reproduction and expanding populations, which suggests the stability of forest structure/composition and further expansion of dominant species. The overall regeneration of trees in the forest had a greater contribution of middle and understorey species. Because of infrequent reproduction and declining populations of some of the dominant native species viz., Abies pindrow, Alnus nepalensis and Betula alnoides, structural/compositional changes in the future are expected in respective forests dominated by them. Abies pindrow and Taxus baccata need immediate attention by forest managers for their survival in the area. Seedlings were found to be more prone to competition from herb and shrubs than saplings.