Maximum Tree Density Research Articles

Phytosociological Analysis of Functional Components in Silvipastoral Land Use Systems of Himachal Pradesh, India

Phytosociological studies are important for devising suitable conservation strategies of the plant genetic resources. Himachal Pradesh is a north-western Himalayan state with diverse landscape having rich and unique floristic diversity. Silvipastoral systems are one among the most prominent agroforestry land use systems which contributes significantly in productivity, ecological balance and livelihood of local communities. Thus, to know the status of floristic and phytosociological diversity in these land use systems, the present study has been conducted from April 2018 to March 2022 in 12 selected villages in Himachal Pradesh. Total number of plant species recorded in study area was 1046 (including 114 tree, 170 shrub and 762 herb species), belonging to 108 families and 538 genera. Poaceae, Asteraceae, Fabaceae, Rosaceae and Lamiaceae were the five most dominant families. Maximum tree density recorded for species Myrica esculenta (980 ind. ha-1) at site 3, Grewia optiva (660 ind. ha-1) at site 2 and Grewia optiva (640 ind. ha-1) at Site 1 Naun, Mandi, followed by Bauhinia variegata (630 ind. ha-1) at Site 2 Banalgi, Solan in zone-II. On the basis of IVI, Cedrus deodara (252.30) was most dominant species followed by Quercus oblongata (193.11), Pinus wallichiana (164.68) and Myrica esculenta (149.10). Among the shrubs Hippophae salicifolia (119.24) was most dominant species followed by Berberis lycium (96.14) and Berberis aristata (90.98). However, Achyranthus aspera (107.66) was most dominant herb species followed by Commelina benghalensis (97.50) and Sonchus asper (44.01). The lowest value of IVI was observed for Capsella bursa-pastoris (9.63) and Tanacetum dolichophyllum (10.54). According to CAMP (Conservation Assessment and Management Prioritization), 2013 nine species viz., Angelica glauca, Berberis aristata, Dioscorea deltoidea, Polygonatum cirrhifolium, Hyoscyamus niger, Bunium persicum, Ephedra gerardiana, Juniperus communis and Selinum vaginatum are threatened and requires conservation and management efforts. In past no study was conducted on floristic and phytosociology diversity of silvipastoral systems of Himachal Pradesh. Hence, present study will definitely act as base line data for further in-depth studies on restoration of degraded lands and silvipastoral system management and improvement programs.

Elevation patterns of tree diversity, composition and stand structure in Mahendragiri Hill Forest, Eastern Ghats of Odisha, India

Tropical mountain forests in Eastern Ghats provide a unique opportunity to relate environmental drivers to plant community structure along elevation gradient. We aimed to investigate the tree diversity, composition and stand structure along elevation gradient and drivers facilitating species distribution across Mahendragiri Hill Forest (MHF) in Eastern Ghats of Odisha, India. Altogether 120 plots of 0.05 ha were established and stems ≥10 cm diameter at breast height were measured. We compared species composition and stand structure among elevation zones. Ordination analysis was used to quantify how community structure was related to topographic, climatic and onsite conditions. In total 189 species representing 131 genera and 51 families were recorded ranging from 64 (MHF6) to 106 species (MHF4). Fabaceae representing 23 species, followed by Phyllanthaceae was dominant families. Maximum tree density and basal area were enumerated in high elevation MHF6 and least disturbed MHF5, respectively. Canonical Correspondence Analysis (CCA) interpreted 58.59% of variation and depicted the role of elevation followed by disturbance and precipitation in species distribution patterns. Variance partitioning analysis shows that topography and disturbance strongly partitioned the dissemination of tree species. Variations in species diversity reflects a direct coupling or interaction of several factors together, making it a complex phenomenon.

Structure and Composition of Vegetation and Status of Invasion in Different Forest Types of Western Himalaya

Present study deals with qualitative and quantitative assessment of vegetation in four most dominated forest types of western Himalaya, Sal (Shorea robusta) forest, Chir-Pine (Pinus roxburghii) forest, Banj-oak (Quercus leucotrichophora), and Deodar forest (Cedrus deodara) between 600 to 2100 m asl elevation. These forests serve the lifeline for local communities for their daily sustenance. A total of 336 species belonging to 277 genera and 98 families were recoded from study area. Total basal cover (TBC) ranged between 24.05 to 35.15 m² ha^-1, Tree density ranged from 472 to 1068, shrub’s density varied between 1930 to 4080 whereas herbs ranged from 53600 to 80008 individual per hectare. Maximum tree density was recorded (1068 ind. ha^-1) at the oak stand and minimum (472 ind. ha^-1) recorded at the Sal forest. Species richness, Shannon-Wiener diversity index and TBC increase from Sal to oak forest. It was observed that temperate oak forests in study area comprised higher diversity and species richness at tree, shrub and herb layer, Sal forest depicted higher regeneration. Major invasive species in study area were Lantana camara, Ageratina adenophora, Ageratum conyzoides and Parthenium hysterophorous. In present study, Ageratina adenophora recorded an elevation of about 2100m asl, which is the alarming sign for local biodiversity and may cause a serious threat to Himalayan biodiversity.

Assessing species abundance and habitat preferences in a part of Nanda Devi Biosphere Reserve, western Himalaya

Present study is an attempt to understand the plant species abundance and habitat preferences using multivariate method in Nanda Devi Biosphere Reserve (NDBR), in western Himalaya. Soil, altitude, slope and differences are reported to be the most important parameters shaping the plant community in the mountains. Two representative areas i.e., Pindari–Sunderdhunga–Kafni site (PSK) of Kumaun region and Lata–Tolma–Phagti site (LTP) of Garhwal region with nineteen forest communities in buffer zone of NDBR have been investigated. All the forest communities were analyzed for assessing community composition and species density in relation to environmental variables. Out of 451 plant species recorded from the study sites, there was a dominance of herbs (70.5%) followed by shrubs (17.7%) and trees (11.8%). Maximum tree density in PSK and LTP sites was recorded in Betula utilis (535 ind ha−1) and mixed T. wallichiana–A. pindrow (1211 ind ha−1) communities respectively. The disturbed habitats in low to mid elevation areas are represented by low canopy cover and high seedling density in PSK site and high non-native species density in LTP site. Both the study sites are dominated by Betula utilis, Taxus wallichiana, Abies pindrow in high elevation areas securing high density of native and endemic species. Habitat preferences of different important species indicate their range of distribution and choice of association with other species.

Carbon stock potential in Pinus roxburghii forests of Indian Himalayan regions

Chir pine (Pinus roxburghii) is the most important tree species used for afforestation programs in the Himalayan regions. In the present study, fourteen forest stands were selected in four different altitudes, i.e., 1801 masl in Garhwal Himalayan of Uttarakhand, India, to assess carbon stock potential of the forest. The study was conducted during 2013–2015. Among the study sites, the maximum tree density (575 ± 90.14 ind. ha−1) was reported in New Tehri (altitude: > 1801 masl) and minimum (135 ± 5.00 ind. ha−1) in Daddi (altitude: 1001–1400 masl). The highest (96 ± 18.36 t ha−1) above-ground carbon stock was estimated in Kandikhal where bole, branch, and foliage contribute 89.93 ± 19.47, 5.17 ± 1.04 and 0.90 ± 0.14 t ha−1, respectively, while lowest (26.68 ± 9.48 t ha−1) was in Gumkhal, and contribution from the same component was found as 20.72 ± 7.84, 4.50 ± 1.58, and 1.47 ± 0.11 t ha−1, respectively. Further, highest value of below-ground carbon was in Kandikhal (28.58 ± 4.81 t ha−1) with an altitude range between 1001 and 1400 masl and the lowest in Gumkhal (9.19 ± 2.87 t ha−1) between 1401 and 1800 masl. Besides, litter production was found higher in the summer season followed by winter and rainy seasons. The study concluded that the density, height, basal area, and volume of Pinus roxburgii varied with altitude, but it was not directional. However, growth patterns and tree density were the key factors in estimating total carbon stocks and further to know the behavior of carbon dynamics (source/sink). Litter production had an inverse relation with altitude; however, increase in litter biomass at > 1801 masl was observed due to new plantations of pine. This study will be highly helpful to the forester and policy-makers in planning carbon mitigation strategies (e.g., catchment area treatment, afforestation activities) at regional and global scales.

Assessment of woody species diversity and composition along a disturbance gradient in Behali Reserve Forest of Biswanath district, Assam, India

The present study was carried out in Behali Reserve Forest, a semi-evergreen forest of Assam, India to record and analyze the woody species diversity and community characteristics using random sampling. Altogether, 35 quadrats (20 m × 20 m) were randomly established and studied from August 2018 to April 2019 spreading across nine study sites. A total of 128 (118 identified and 10 unidentified) woody species from 83 genera and 43 families were found in the sampled area of 1.4 ha. Lauraceae with 19 species was the richest family by species followed by Euphorbiaceae and Phyllanthaceae (eight species each). Altogether, 787 individuals were recorded from the sampled plots and the stand density ranged between 250 individuals × ha-1 to 725 individuals × ha-1 with mean stand density of 543 individuals × ha-1. Species-wise density analysis revealed that Magnolia hodgsonii (96.43 individuals × ha-1) has the maximum tree density. Plot wise analysis showed that Dikal (58.32 m2 × ha-1) recorded the maximum basal area as well as the equitability index of 0.95. In Serelia, we recorded the highest Simpson index (0.92), Shannon H index (2.76), Brillouin index (2.11), Menhinick (3.49), Margalef (5.29) and Fisher alpha index (26.59). In Radhasu, we recorded maximum evenness (0.90), dominance (0.58) and Berger-Parker index (0.65). The maximal values of Chao index (38.53) was recorded in Hatimara. Our study also revealed that diversity was maximal for the community under medium level of disturbance in the reserve, while communities under the lowest and highest disturbance pressure had minimal diversity. The Behali Reserve Forest exhibited a great species richness (118 species), mean basal area (44.42 m2 × ha-1) and stand density (in total, 788 individuals per study area of 1.4 ha) compared to the other forests of the northeastern region of India.

Impact of disturbance on vegetation, biomass and carbon stock in tropical forests of Tripura, Northeast India

In this study, the impact of anthropogenic disturbances on vegetation, soil characteristics, biomass and carbon stock was studied in tropical mixed deciduous forests of Tripura, North-east India. The forests stands were selected based on the presumed disturbance index and categorized in three distinct categories viz. Least Disturbed Forests (LDF), Moderately Disturbed Forests (MDF) and Highly Disturbed Forests (HDF). The study revealed that species diversity is much higher in LDF followed by MDF and HDF sites. Few species like Anogeissus accuminata, Lannea coromandelica, Schima wallichii, and Syzygium cumini are common in all the three categories of forests. The Shannon–Wiener diversity index ranged from 1.32 to 2.51 in all the stands. The phytosociological parameters varied along the disturbance gradient in different stands. The maximum tree density was 198.57 trees ha−1 in LDF, 176.67 trees ha−1 in MDF and least in HDF (111.67 trees ha−1). Soil Organic Carbon (SOC %) recorded maximum in LDF (1.41–1.67%) and minimum in HDF (0.91–1.36%). Tree biomass showed a significant relation with soil organic carbon stock (r = 0.998, p < 0.05). Furthermore, the present study suggests the need for quantification of forest disturbance and biomass which will improve carbon budget estimates and lead to better parameterization of forest carbon cycle models.

Agroforestry development in Europe: Policy issues

Agroforestry is considered a sustainable form of land management that optimizes the use of natural resources (nutrients, radiation, water). Agroforestry is defined as the deliberate integration of woody vegetation with agricultural activities in the lower story. It provides a higher biomass production per unit of land, while providing more ecosystem services than woody-less agricultural lands, such as the reduction of soil erosion and nitrogen leaching, and increase carbon sequestration and landscape biodiversity. The objective of this paper is to evaluate the past and current European Union Common Agricultural policies aiming at promoting the afforestation or reforestation of lands, as the introduction of trees can be seen as a first step to carry out agroforestry practices in former agricultural or forest lands. Agroforestry was a traditional land use system in Europe before modern times. However, before the sixties land intensification and consolidation destroyed millions of trees all over Europe. On the contrary, some good examples of agroforestry promotion are found in Eastern European countries in order to reduce the effect of extreme events such as winds, flooding at the beginning and mid of the last century. In Western European countries, the introduction of trees in the land has been promoted by agroforestry, afforestation and reforestation at the end of the last century. Afforestation of agricultural lands have been the most successful CAP measure (over 1 million hectares) while agroforestry measures were not extensively adopted which may be explained by the funds associated to afforestation measure which compensated the losses of income 15 or 20 years in afforested lands. Agroforestry was poorly adopted in the CAP 2007–2013, having a better success in the CAP 2014–2020 due to the recognition of woody vegetation and the compensation of 5 years given for maintenance once agroforestry is established. However, policy rules ensuring Pillar I payment when agroforestry measure is adopted such as a management plans ensuring that maximum tree density (100 trees per hectare) is not reached, should be pursued.

Regeneration dynamics, population structure, and forest composition in some ridge forests of the Western Himalaya, India

ABSTRACTThe present study aimed to analyze the regeneration dynamics, population structure, and forest composition in some ridge forests of the Western Himalaya to elucidate the impact of climate change. The highest species richness (trees, 17; saplings, 16; seedlings, 16) was recorded in mixed Rhododendron arboreum forest. The maximum tree density (737 ± 25.93 trees ha−1; mixed Quercus floribunda); sapling density (5342 ± 587.54 saplings ha−1; mixed Quercus semecarpifolia), and seedling density (71,429 ± 26,632.29 seedlings ha−1; mixed Cedrus deodara) were recorded in forests of higher altitudes. The mean basal cover values in these forests oscillated between 39.21 ± 1.53 m2 ha−1 (mixed Quercus leucotrichophora) to 87.65 ± 15.45 m2 ha−1 (mixed Abies pindrow). The highest Shannon index value (0.51 ± 0.05) and species evenness (0.36 ± 0.02) for trees were recorded in mixed Rhododendron arboreum forest. Some species like Betula utilis, Myrica esculenta, Ficus rumphii, Ilex dipyrena, Quercus floribunda, Litsea elongata, Symplocos paniculata, and Abies spectabilis were noticed as new recruiters (recent invaders) in new habitats, which may change the future forest composition. This study revealed that ridge forests of the Bhagirathi catchment area were in transition phase at middle altitudes. Mixed Quercus floribunda forest was observed to be the youngest regenerating forest; however, mixed Abies pindrow forest was the most mature old-growth forest.

Population structure and regeneration status of Vitellaria Paradoxa (C. F. Gaertner) under different land management regimes in Atacora department, Benin

Vitellaria paradoxa (shea) parklands are one of the major features of the Sudanian savannah. Besides the parklands importance in terms of provision of ecosystem services, they play a major role in satisfying household subsistence needs. However, the shea trees on farms are under threat due to the increasing population growth, inappropriate agricultural practices and increasing effects of climate change. Thus, we examine the V. paradoxa population structure and its regeneration status in parklands under different land management regimes in four communes of Atacora department in Northern Benin. Dendrometric parameters were measured in five plots of 50 × 50 m in each commune and land management regime and the number of seedling and coppice were assessed. We applied Weibull theoretical model to compare measured and expected diameter classes’ densities. The tallest and largest individuals were recorded in fields while old fallows had the maximum tree density and regeneration across sites. In over-all, the tree densities across sites as well as regeneration were low in fields and young fallows. We also found that the land management regime significantly influenced regeneration particularly the coppices. On the other hand, the distribution of diameter classes showed that shea agroforests was represented by small diameter classes implying a stable and regenerating population in 92 % of visited sites, irrespective of the land management regime. Thus, the state of regeneration in shea parklands appeals for an improvement in the management of juveniles, a guaranty of future stable population.

Vegetation and Soil Characteristics of Plantations in a Part of Western Himalaya

Recognizing the role of plantations in bioresource conservation, four plantations namely Department of Non-renewable Energy Sources (DNES), Eucalyptus, Rose, and Tea were surveyed and sampled in a part of Western Himalaya. Total of 96 plant species belonging to 52 families were recorded from the plantations. Poaceae, Asteraceae and Rosaceae were the dominant families while seven species namely Bidens pilosa, Clinopodium vulgare, Erigeron annuus, Euphorbia heterophylla, Eupatorium adenophorum, Oxalis corniculata, and Pouzolzia zeylanica were common to all the plantations. Maximum tree density was recorded in DNES plantation (36.63±28.10/100m2), while maximum shrub density was in Tea plantation (20.50±2.10/25 m2). Rose plantation, on the other hand, had the highest herb density (210.83±57.30/m2). Tree (2.547) and shrub diversity (2.382) was highest in DNES, while the herb diversity was highest (2.594) in Tea plantation. The pH of the soil from these plantations 4.37 in Tea plantation to 4.77 in Rose plantation. Amongst the four plantations, maximum similarity was between DNES and Eucalyptus plantations (22%) and added together the four plantations account for 3% of the Flora of Himachal Pradesh.

广西马山岩溶植被年龄序列的群落特征

Desertified karst region is a focal and difficult area of vegetation recovery and ecological restoration in southwest China. We investigated changes of the regeneration,succession and community characteristics in karst vegetation after stopping human disturbance,based on a chronosequence in the kart region of Mashan county. Our sampling includes 15plots,each of 20 m×50 m representing five successional stages( desertified karst land,grassland,scrub,young forest and mature forest). We found that vegetation succession proceeded from desertified karst land to grassland to scrub to young forest,and finally to mature forest. Vegetation cover was significant different among different successional communities at three different layers( P0. 05). The greatest cover of arbor layer was found in mature forests,of shrub layer was in young forests,and of grass layer was in scrub stage,while the maximum number of species,genera and families with importance values( IV) ≥10. 00 were found in young forests. Community structures of all layers were remarkably different among successional stages,so were plant density of the tree layer,with the maximum tree density found in young forests. Plant density of the shrub layer in the mature forests was significantly lower than that in young forests and grasslands( P0. 05),and was not significantly different with desertified karst lands and scrubs( P 0. 05). Species richness of the communities increased with succession,but the changes were different among all layers in different successional stages. The greatest species richness in the grass layer was found in the grassland and the lowest in the mature forest; the greatest species richness in the shrub layer was found in the young forest and the lowest in the desertified karst land stage; the greatest species richness in the tree layer was found in the young forest and the least in the mature forest. Ecological dominance was not significantly different among grass layers in different successional stages( P 0. 05),but significantly different among shrub and arbor layers in different successional stages( P0. 05). The restoration of karst vegetation can be divided into two stages,each with a threshold,i. e. harsh physical environments and deficiency of climax species,respectively. At each stage,the successive direction and speed depended on the presence of different driving and keystone species with different functional characteristics. The later a successional stage was,the more aboundance of climax species,and the more obvious it was that the driving and keystone species were those of advanced,large-sized and long-lived.

Limitations on maximum tree density using hyperspatial remote sensing and environmental gradient analysis

We present a novel approach for performing environmental gradient analysis to address the question: is maximum potential tree density in eastern Lake Tahoe Basin, NV limited by water, temperature/energetic constraints, or both? To address this question we fuse continuous tree density estimates derived from hyperspatial remote sensing imagery (pixels smaller than trees) with two topographically derived environmental gradients: elevation and yearly potential relative radiation (PRR). We based our analysis on the maximum tree density found in each of over 200 environmental gradient combinations found with our area of interest, drawing from a dataset consisting of over 300,000 30 m plots and over 3 million individual trees. At a given elevation, sites in which maximum tree density increases as a function of increasing yearly PRR were considered to be temperature or energy limited. Conversely, sites in which maximum tree density decreased as a function of increasing yearly PRR were considered water limited. We found that eastern Lake Tahoe appears to be a landscape which is both water limited (at lower elevation and brighter, south-facing slopes) and temperature/energy limited (at higher elevations and darker, north-facing slopes). We discuss how fusing accurate and ecologically relevant remote sensing outputs with direct and indirect continuous microclimate surfaces can provide a powerful tool for addressing major questions of tree distributions and life history parameters.

Comparison of Methods to Estimate Reineke's Maximum Size-Density Relationship Species Boundary Line Slope

Abstract Maximum size-density relationships (MSDR) provide natural resource managers useful information about the relationship between tree density and average tree size. Obtaining a valid estimate of how maximum tree density changes with changes in average tree size is necessary to describe these biological relationships accurately. This article examines three methods to estimate the slope (b) of the MSDR species boundary line across a range of planting densities: ordinary least-squares (OLS), first-difference model, and the linear mixed-effects model. For this article, stability refers to the extent to which parameter estimates do not change when the range of planting densities in the fitting data set changes. When using data from a planting density trial consisting of planting densities ranging from 6,727 to 747 seedlings per hectare, mixed-effect models produced the most stable estimates of b while OLS resulted in the least stable estimates. MSDR boundaries have been defined as either (1) those that describe the boundaries of individual stands (MSDR dynamic thinning line) or (2) those that describe MSDRs common across all sites for a particular species in a certain geographical region (MSDR species boundary line). A further refinement of the MSDR species boundary line is proposed by defining two MSDR species boundary lines, labeled here as I and II. Although both MSDR species boundary lines are positioned above all observations, one MSDR species boundary line, II, has a slope that can be considered the population average of all MSDR dynamic thinning lines; the other species boundary line (I) has a slope that results from positioning the boundary above all observations without accounting for self-thinning patterns of individual stands. A mixed-effects analysis was used to estimate the slope of MSDR species boundary line II.

Development of current stand structure in dry fir-pine forests of eastern Washington

Stand reconstruction, using live trees and deadwood, provided a four to five hundred year recruitment history for the current stand structure in dry fir-pine forests of northern Washington, USA. The lengthy structural record indicated these dry fir-pine forests were resilient to change, that all forest conditions were transient, and that forests were currently transitioning away from maximum tree density levels. Historically, frequent fires maintained low tree abundance, but fire cycles lengthened in the 1860s as Euro-settlement progressed. Average stand density had already increased to 194% (SD = 116) of 1860 levels by the start of effective fire suppression in 1915. From the 1930s to 1960s, average stand density peaked at 258% (SD = 98) of 1860 levels. By 2000, tree mortality in these overstocked stands had reduced average stand densities to 68% (SD = 19) of maximum levels. However, tree densities in 2000 still averaged 173% (SD = 64) above historical levels. Although there had been significant tree recruitment and a century without fire, the trees present in the historic stands provided 75% (SD = 13) of the basal area in 2000. Numerous understory (< 7.6 cm dbh) trees (252 trees/ha, SD = 97) were present in 1860 stands and these trees contributed more basal area than the historic overstory in 2000. In the absence of fire and without human intervention, the sampled stands have decreased in overall tree density from maximum levels while representation of shade-tolerant species, range and evenness of age-class structure, and abundance of old forest (live tree and deadwood) legacies have increased.

A plant functional approach to the prediction of changes in Australian rangeland vegetation under grazing and fire

Abstract. Grazing by domestic livestock and changed fire regimes by humans have caused major changes in the productivity and composition of rangelands in Australia and other continents. Of particular concern are the commonly observed loss of perennial forage species and the increasing abundance of woody plants. Grazing and fire‐induced changes are difficult to predict from current process knowledge and are often too costly or time‐consuming to investigate experimentally. We describe the development and use of ARENA, a new simulation model. A plant functional approach is used in which the relative growth rate, competitive ability and life cycle of the plant types are mainly defined by the plant's morphology and allocation pattern, plus its water‐use efficiency and nitrogen concentration. The soil and plant types can be parameterized to a large extent with information from the literature, facilitating application in a broad range of dryland environments. The model has been tested for two soils and pasture communities in the seasonally dry tropics of the Victoria River District, N Australia. Predictions of pasture production and perennial grass fraction under undisturbed conditions agreed with observations in field exclosures. Predictions of maximum tree density also coincided with observations along a rainfall gradient. Simulation experiments were conducted to explore the effect of different stocking levels and fire management regimes on pasture productivity and composition. Responses of pastures on red loam and grey clay soils were generally consistent with regional field experience, but the model did not reproduce the expected changes in the abundance of woody plants.