An Analysis of Vegetation Restoration on Opencast Oil Shale Mines in Estonia

We compared four types of 30‐year‐old forest stands growing on spoil of opencast oil shale mines in Estonia. The stand types were: (1) natural stands formed by spontaneous succession, and plantations of (2) Pinus sylvestris (Scots pine), (3) Betula pendula (silver birch), and (4) Alnus glutinosa (European black alder). In all stands we measured properties of the tree layer (species richness, stand density, and volume of growing stock), understory (density and species richness of shrubs and tree saplings), and ground vegetation (aboveground biomass, species richness, and species diversity). The tree layer was most diverse though sparse in the natural stands. Understory species richness per 100‐m² plot was highest in the natural stand, but total stand richness was equal in the natural and alder stands, which were higher than the birch and pine stands. The understory sapling density was lower than 50 saplings/100 m² in the plantations, while it varied between 50 and 180 saplings/100 m² in the natural stands. Growing stock volume was the least in natural stands and greatest in birch stands. The aboveground biomass of ground vegetation was highest in alder stands and lowest in the pine stands. We can conclude that spontaneous succession promotes establishment of diverse vegetation. In plantations the establishment of diverse ground vegetation depends on planted tree species.     

黑龙江省不同地点蒙古栎林生态特点研究

通过对黑龙江省６个地点的天然蒙古栎林的结构和更新特点的分析,蒙古栎林可划分为不同特点的蒙古栎群落,即纯蒙古栎群落、蒙古栎桦树群落、蒙古栎槭树群落、蒙古栎红松群落和蒙古栎松混交林群落,其演替趋势如下：红蒙古栎群落、蒙古栎桦树群落至蒙古栎槭树落、蒙古栎红松群落,再至蒙古栎红松混交林群落,蒙古栎群落类型的多样性主要反应群落不同的演替阶段,造成蒙古栎群落多样的原因是人类活动和自然因素作用的结果,随着群落的演替,蒙古栎的优势地位逐渐被消弱,乔木种类丰富度增多,草本种类丰富度增多;蒙栎的相对密度下降,林内环境由于干燥逐渐变中性至较湿润,蒙古栎幼苗和幼树在总幼苗和幼树中所占的比例下降,耐荫物中色木槭等的幼苗和幼树所占比例上升;在演替过程中,蒙古栎分布格局－聚集分布的聚集程度逐渐降低,并向随机分布的方向发展。     

Carbon of Chaillu forests based on a phytosociological analysis in Republic of Congo,more than meets the eye?

The objectives were to quantify aboveground, belowground and dead wood carbon pools near Mayoko in the Chaillu massif of Republic of Congo and explore relationships between carbon storage and plant diversity of all growth forms. A total of 190 plots (25 m by 25 m) were sampled (5072 stems, 211 species) and data analysed using recommended central-African forest allometric equations. Mean stem diameter at breast height was 33.6 cm, mean basal area 47.7 m² ha⁻¹ and mean density of individuals 407 ha⁻¹. Mean aboveground carbon (AGC) ranged from 13.93–412.66 Mg C ha⁻¹, belowground carbon from 2.86–96.97 Mg C ha⁻¹ and dead wood from 0.00–7.59 Mg C ha⁻¹. The maximum AGC value recorded in a plot was 916 Mg C ha⁻¹. The analysis performed using phytosociological association as basis rather than broad vegetation type is unique. AGC values for undisturbed terra firme forest sites featured among the highest recorded for African tropical forests. Considering only tree diversity, a weak, yet significant, relationship existed between AGC and species richness, Shannon-Wiener index of diversity and Fisher's alpha. However, if diversity of all plant growth forms is considered, no relationship between carbon and plant diversity existed.     

The legacy of harvest and fire on ecosystem carbon storage in a north temperate forest

Forest harvesting and wildfire were widespread in the upper Great Lakes region of North America during the early 20th century. We examined how long this legacy of disturbance constrains forest carbon (C) storage rates by quantifying C pools and fluxes after harvest and fire in a mixed deciduous forest chronosequence in northern lower Michigan, USA. Study plots ranged in age from 6 to 68 years and were created following experimental clear‐cut harvesting and fire disturbance. Annual C storage was estimated biometrically from measurements of wood, leaf, fine root, and woody debris mass, mass losses to herbivory, soil C content, and soil respiration. Maximum annual C storage in stands that were disturbed by harvest and fire twice was 26% less than a reference stand receiving the same disturbance only once. The mechanism for this reduction in annual C storage was a long‐lasting decrease in site quality that endured over the 62‐year timeframe examined. However, during regrowth the harvested and burned forest rapidly became a net C sink, storing 0.53 Mg C ha⁻¹ yr⁻¹ after 6 years. Maximum net ecosystem production (1.35 Mg C ha⁻¹ yr⁻¹) and annual C increment (0.95 Mg C ha⁻¹ yr⁻¹) were recorded in the 24‐ and 50‐year‐old stands, respectively. Net primary production averaged 5.19 Mg C ha⁻¹ yr⁻¹ in experimental stands, increasing by < 10% from 6 to 50 years. Soil heterotrophic respiration was more variable across stand ages, ranging from 3.85 Mg C ha⁻¹ yr⁻¹ in the 6‐year‐old stand to 4.56 Mg C ha⁻¹ yr⁻¹ in the 68‐year‐old stand. These results suggest that harvesting and fire disturbances broadly distributed across the region decades ago caused changes in site quality and successional status that continue to limit forest C storage rates.     

Effects of population density on forest structure and species richness and diversity of trees in Kampong Thom Province, Cambodia

This study examined differences in stand structure, tree species richness, and tree species diversity in relation to population density in Kampong Thom Province, Cambodia. Tree data were obtained from a 1997 forest inventory involving 60 clusters (540 plots) systematically distributed over 30% of the provincial forest area. Spatially referenced population data were obtained from the 1998 national population census. The average number of trees per cluster was 356/ha, the average basal area, 23 m²/ha, the average stand volume, 217 m³/ha, and the average aboveground biomass, 273 Mg/ha for all trees of DBH 10 cm and larger. The average species richness per cluster was 37 species, while average species diversity was measured as 0.916 using Simpson’s index and 2.98 by Shannon’s index. Significant negative correlations were generally found between population density surrounding clusters and tree density, basal area, stand volume, aboveground biomass, and species richness and diversity for three examined diameter classes (DBH of 10–30, ≥30, and ≥10 cm). As the distance from clusters for calculating population density increased, the correlation levels increased up to 5 or 7 km, depending on the variables and diameter class, and then stayed relatively constant for stand structure variables and decreased for species richness and diversity. The results indicate that evidence of disturbance was more pronounced at higher population density up to around 5 to 7 km. We suggest that introduction of greater controls on human disturbance should be a high priority for resource management and conservation in Kampong Thom Province and, presumably, Cambodia as a whole.     

Patterns of Biomass and Carbon Distribution across a Chronosequence of Chinese Pine (Pinus tabulaeformis) Forests

Patterns of biomass and carbon (C) storage distribution across Chinese pine (Pinus tabulaeformis) natural secondary forests are poorly documented. The objectives of this study were to examine the biomass and C pools of the major ecosystem components in a replicated age sequence of P. tabulaeformis secondary forest stands in Northern China. Within each stand, biomass of above- and belowground tree, understory (shrub and herb), and forest floor were determined from plot-level investigation and destructive sampling. Allometric equations using the diameter at breast height (DBH) were developed to quantify plant biomass. C stocks in the tree and understory biomass, forest floor, and mineral soil (0–100 cm) were estimated by analyzing the C concentration of each component. The results showed that the tree biomass of P. tabulaeformis stands was ranged from 123.8 Mg·ha^–1 for the young stand to 344.8 Mg·ha^–1 for the mature stand. The understory biomass ranged from 1.8 Mg·ha^–1 in the middle-aged stand to 3.5 Mg·ha^–1 in the young stand. Forest floor biomass increased steady with stand age, ranging from 14.9 to 23.0 Mg·ha^–1. The highest mean C concentration across the chronosequence was found in tree branch while the lowest mean C concentration was found in forest floor. The observed C stock of the aboveground tree, shrub, forest floor, and mineral soil increased with increasing stand age, whereas the herb C stock showed a decreasing trend with a sigmoid pattern. The C stock of forest ecosystem in young, middle-aged, immature, and mature stands were 178.1, 236.3, 297.7, and 359.8 Mg C ha^–1, respectively, greater than those under similar aged P. tabulaeformis forests in China. These results are likely to be integrated into further forest management plans and generalized in other contexts to evaluate C stocks at the regional scale.     

Coastal heathland succession influences butterfly community composition and threatens endangered butterfly species

Succession has a strong influence on species diversity and composition of semi-natural open terrestrial ecosystems. While several studies examined the effects of succession on butterflies in grassland and forest ecosystems, the response of heathland butterflies to succession had not been investigated so far. To address this issue we sampled butterfly abundance and environmental parameters on the Baltic island of Hiddensee (NE Germany) along a gradient of coastal heathland succession from grey dunes to birch forest. Our results provide evidence that succession of coastal heathland has a strong influence on butterfly diversity, abundance, and species composition. Thereby grass and tree encroachment present the main threats for heathland butterflies. Diversity and abundance of butterflies were highest in shrub-encroached heath directly followed by early stages of coastal heathland succession (dwarf-shrub heath, grey dune). Both observed threatened species (Hipparchia semele, Plebeius argus) were negatively affected by succession: abundance decreased with increasing vegetation density (both species) and grass cover (P. argus); consequently, the two later successional stages (shrub, birch forest) were not occupied. Our findings highlight the importance of the preservation of early stages of coastal heathland succession for endangered butterfly species. For coastal heathland management we therefore suggest to maintain early successional stages by sheep grazing, mowing or, in case of high nutrient contents, intensive techniques such as sod-cutting or choppering. To a lower extend shrub-encroached sites should also be present, which might be beneficial for overall species richness.     

Biomass carbon storage and net primary production in different habitats of Hunshandake Sandland, China

Terrestrial ecosystems are playing important roles in global carbon cycling. However, the information is still limited with regard to the semi-arid sandland or desert area, compared with the thorough studies on forest and grassland. We here estimated the biomass carbon storage, net primary production (NPP) and rain use efficiency (RUE) of Hunshandake Sandland, a semi-arid sandy region in Inner Mongolia covered with vegetation of Siberian elm (Ulmus pumila L.) sparse forest grassland. Five main habitats, i.e. fixed dunes, semi-fixed dunes, shifting dunes, lowland, and wetland, were compared to analyze the patterns of carbon storage and NPP distribution. The average biomass (9.19 Mg C ha^?1) and NPP (4.79 Mg C ha^?1 yr^?1) of the sparse forest grassland were respectively 82% and 54% higher than the mean level of the surrounding temperate grassland. Governed by the same climate, sparse forest grassland ecosystem had RUE almost twice that of surrounding grassland. The ratio of below to aboveground biomass was 3.5: 1 in the sandland, indicating that most of the vegetational carbon was stored in belowground pool. Although trees were functionally critical in maintaining the integrity of sparse forest grassland, they accounted for only 10.6% and 1.2% of the biomass and NPP, respectively. The sparse forest grassland in Hunshandake Sandland should be recognized as a temperate savanna ecosystem which is distinctively different from typical temperate grassland in the same region as evidenced by the higher NPP and vegetation carbon storage. Well designed management and restoration efforts can potentially sustain ecosystem services in both forage production and carbon sequestration.     

Species diversity and community structure in sal (<Emphasis Type="Italic">Shorea robusta</Emphasis>) forests of two different rainfall regimes in West Bengal,India

Knowledge on the structure and composition of the plant communities has enormous significance in conservation and management of forests. The present study aimed to assess the community attributes, viz., structure, composition and diversity in the moist and dry sal (Shorea robusta) forests in the West Bengal province of India and compare them with the other sal forests of India. The phytosociological data from these forests were quantitatively analysed to work out the species richness, diversity, evenness, dominance, importance value, stand density and the basal area. The analysis showed that plant richness and diversity in moist sal forests of northern West Bengal are higher than the dry sal forests of south-west Bengal; a total of 134 tree (cbh ≥30 cm), 113 shrub and 230 herb species were recorded in the moist sal forest compared to 35 tree, 41 shrub and 96 herb species in dry sal forest. Papilionaceae was observed to be the dominant family. Dry sal forests had higher tree dominance (0.81) and stand density (1,006 stems ha⁻¹) but lower basal area (19.62 m²ha⁻¹) while moist sal forest had lower tree dominance (0.18) and stand density (438 stems ha⁻¹) but higher basal area (56.52 m²ha⁻¹). Tree species richness and stem density across girth classes in both the types decreased from the smallest to largest trees, while the occurrence rate of species increased with increase in girth class. A t-test showed significant differences in species richness, basal area and the stand density at 95% confidence level (p = <0.05) in the two forest types. The CCA indicated very low overall match (canonical correlation value = 0.40) between the two sets of variables from moist and dry sal types. The differences in these forests could be attributed to the distinct variations in climatic conditions- mainly the rainfall, disturbance regimes and the management practices.     

Biomass carbon storage and net primary production in different habitats of Hunshandake Sandland, China

Terrestrial ecosystems are playing important roles in global carbon cycling. However, the information is still limited with regard to the semi-arid sandland or desert area, compared with the thorough studies on forest and grassland. We here estimated the biomass carbon storage, net primary production (NPP) and rain use efficiency (RUE) of Hunshandake Sandland, a semi-arid sandy region in Inner Mongolia covered with vegetation of Siberian elm (Ulmus pumila L.) sparse forest grassland. Five main habitats, i.e. fixed dunes, semi-fixed dunes, shifting dunes, lowland, and wetland, were compared to analyze the patterns of carbon storage and NPP distribution. The average biomass (9.19 Mg C ha^?1) and NPP (4.79 Mg C ha^?1 yr^?1) of the sparse forest grassland were respectively 82% and 54% higher than the mean level of the surrounding temperate grassland. Governed by the same climate, sparse forest grassland ecosystem had RUE almost twice that of surrounding grassland. The ratio of below to aboveground biomass was 3.5: 1 in the sandland, indicating that most of the vegetational carbon was stored in belowground pool. Although trees were functionally critical in maintaining the integrity of sparse forest grassland, they accounted for only 10.6% and 1.2% of the biomass and NPP, respectively. The sparse forest grassland in Hunshandake Sandland should be recognized as a temperate savanna ecosystem which is distinctively different from typical temperate grassland in the same region as evidenced by the higher NPP and vegetation carbon storage. Well designed management and restoration efforts can potentially sustain ecosystem services in both forage production and carbon sequestration.     

Biomass,carbon density and diversity of tree species in tropical dry deciduous forests in Central India

Tropical dry deciduous forests play a significant role in regulating the biogeochemical cycles. Present study assesses the carbon stock of tropical dry deciduous forests varying in tree density, basal cover, and diversity located in Singrauli district of Madhya Pradesh in Central India. Field sampling was carried out in six forest sites viz., Chitrangi, East Sarai, Gorbi, Renukoot, West Sarai, and Waidhan, of Singrauli. A total of 29 tree species belonging to 18 families were recorded across the forest ranges where tree density, basal area and diversity values varied from 702 (Gorbhi Range) – 1671 (East Sarai range) individuals ha^?1; 15.43 (Renukhund range) – 71.76 m² ha^?1 (Chitrange range) and 0.69 (West Sarai range) – 2.52 (Gorbi range), respectively. Total biomass estimated ranged from 103.32 (Renukhund range) – 453.54 Mg ha^?1 (Chitrange range) while the total tree carbon density varied from 48.97 to 214.97 Mg C ha^?1. The variation in carbon storage in the studied ranges was found dependent on density of trees in different diameter and age classes and tree species diversity. Diospyros melanoxylon, Butea monosperma, Shorea robusta, Senegalia catechu, Spondias pinnata, and Lagerstroemia parviflora were the dominant species at different study sites (forest ranges) and contributed towards higher carbon storage in respective forest ranges. Study endorses field-based approach for carbon estimations based on above and belowground assessments as a more realistic approach to understand sink potential of natural forests.     

4种不同演替阶段森林群落物种组成和多样性的比较研究

通过空间变化代替时间差异和样方法等手段,对浙江省马尾松林针叶（针叶林）、马尾松针阔叶混交林、中龄常绿阔叶林和近熟常绿阔叶林4种不同演替阶段森林群落的物种组成和多样性、群落间相似性进行了研究。结果表明,23个样地共记录维管植物53科105属170种。随着演替的进行,群落物种数、各层次的Shannon-Wiener多样性指数基本上呈现先下降后上升的趋势,并以针阔叶混交林最低,估计跟先锋物种的消失和后期物种的出现这一更替有关。随着演替的进行,各群落间的Jaccard相似性系数逐渐降低,其中针阔叶混交林和中龄常绿阔叶林之间的相似性系数最高,马尾松与近熟常绿阔叶林之间的相似性系数最低。群落主成分分析也得出相似的结果。群落之间的差异主要体现在物种组成尤其是乔木层的组成上;针阔叶混交林是物种丰富度和物种多样性较低的一个群落,但它与其它群落间的相似性较高,并已储存了常绿阔叶林中的大部分物种,对演替起着承前启后的作用。     

Modeling above‐ground litterfall in eastern Mediterranean conifer forests using fractional tree cover,and remotely sensed and ground data

Question: How can we model above‐ground litterfall in Mediterranean conifer forests using remotely sensed and ground data, and geographic information systems (GIS)? Location: Eastern Mediterranean conifer forest of Turkey. Methods: Above‐ground litterfall from Mediterranean forest stands of Pinus nigra, Cedrus libani, Pinus brutia and Juniperus excelsa and mixed Abies cilicica, C. libani and P. nigra was modeled as a function of fractional tree cover using a regression tree algorithm, based on IKONOS and Landsat TM/ETM+data. Landsat TM/ETM+images for the study area were used to map actual stand patterns, based on a land‐cover map of species stands using a supervised classification. Results: Total amount of annual above‐ground litterfall for the entire study area (12 260 km²) was estimated at 417.2 Mg ha^?1 for P. brutia, 291.1 Mg ha^?1 for the mixed stand, 115.5 Mg ha^?1 for P. nigra, 54.6 Mg ha^?1 for J. excelsa and 45.9 Mg ha^?1 for C. libani. The maps generated indicate the distribution of the seasonal amount of total above‐ground litterfall for different species and the distribution of species stands in the study area. There was an increase in the amount of above‐ground litterfall for P. brutia stand in summer, for J. excelsa in autumn and for C. libani, P. nigra and the mixed stand of A. cilicica, P. nigra and C. libani in winter. Conclusion: Application of this model helps to improve the accuracy of estimated litterfall input to soil organic carbon pools in the Mediterranean conifer forests.     

Experimental Manipulation of Forest Structure: Near-Term Effects on Gap and Stand Scale C Dynamics

Canopy gaps and coarse woody debris are two forest structural features that are more abundant in old-growth forests than in second-growth, even-aged stands. These features directly influence the carbon balance of the ecosystem, yet few studies have quantified their interactive effects. We experimentally manipulated the forest structure of a second-growth northern hardwood forest in north-central Wisconsin (USA) and measured the shift of C between pools of the ecosystem components. Here, we question the longevity of the changes to the aboveground pools and address their implications for total ecosystem C (TEC) and net ecosystem production (NEP) at both the gap and stand scale. At the scale of the gap, the harvest and removal of trees significantly reduced NEP (?3.2 to ?3.5 Mg C ha^?1 for gaps vs 2.2 to 2.5 Mg C ha^?1 for reference conditions), but did not alter heterotrophic respiration. The addition of woody debris without harvest significantly increased heterotrophic respiration, decreasing soil C storage of the gap area (?0.5 to ?1.1 Mg C ha^?1). The combined treatment of gap creation and woody debris addition made the gap area a significant C source to the atmosphere for the 3 years of the study (?4.9 to ?5.1 Mg C ha^?1). We also estimated how these structural features would affect C dynamics at a broader scale. The conversion of 10% of the stand canopy to gap conditions caused only a brief decrease in the stand NEP with the C balance returning to reference conditions by the third year following tree harvest. The woody debris additions caused an increase in both TEC and heterotrophic respiration. When combined the addition of canopy gaps and woody debris caused plots to initially become significant C sources, relative to undisturbed locations that were consistently accumulating C, with an annual NEP ranging from 2.1 to 2.8 Mg C ha^?1 y^?1. Understanding the effects of these structural features on forest C dynamics is highly relevant as the maturing forests of the region transition to more structurally complex forests and the demand for managing ecosystems for long-term C sequestration increases.     

Variation in biomass and carbon storage by stand age in pine (Pinus tabulaeformis) planted ecosystem in Mt. Taiyue,Shanxi, China

Forest ecosystems play dominant roles in global carbon budget because of the large quantities stored in live biomass, detritus, and soil organic matter. Researchers in various countries have investigated regional and continental scale patterns of carbon (C) stocks in forest ecosystems; however, the relationship between stand age in different components (vegetation, forest floor detritus, and mineral soil) and C storage and sequestration remains poorly understood. In this paper, we assessed an age sequence of 18-, 20-, 25-, 38-, and 42-year-old Pinus tabulaeformis planted by analyzing the vertical distribution of different components biomass with similar site conditions on Mt. Taiyue, Shanxi, China. The results showed that biomass of P. tabulaeformis planted stands was ranged from 88.59 Mg ha^?1 for the 25-year-old stand to 231.05 Mg ha^?1 for the 42-year-old stand and the major biomass was in the stems. Biomass of the ground vegetation varied from 0.51 to 1.35 Mg C ha^?1 between the five stands. The forest floor biomass increased with increasing stand age. The mean C concentration of total tree was 49.94%, which was higher than C concentrations of ground vegetation and forest floor. Different organs of trees C concentration were between 54.14% and 47.74%. C concentrations stored in the mineral soil for each stand experienced decline with increasing soil depth, but were age-independent. Total C storage of five planted forests ranged from 122.15 to 229.85 Mg C ha^?1, of which 51.44–68.38% of C storage was in the soil and 28.46–45.21% in vegetation. The study provided not only with an estimation biomass of P. tabulaeformis planted forest in Mt. Taiyue, Shanxi, China, but also with accurately estimating forest C storage at ecosystem scale.     

Do lianas shape ant communities in an early successional tropical forest?

Almost half of lowland tropical forests are at various stages of regeneration following deforestation or fragmentation. Changes in tree communities along successional gradients have predictable bottom‐up effects on consumers. Liana (woody vine) assemblages also change with succession, but their effects on animal succession remain unexplored. Here we used a large‐scale liana removal experiment across a forest successional chronosequence (7–31 years) to determine the importance of lianas to ant community structure. We conducted 1,088 surveys of ants foraging on and living in trees using tree trunk baiting and hand‐collecting techniques at 34 paired forest plots, half of which had all lianas removed. Ant species composition, β‐diversity, and species richness were not affected by liana removal; however, ant species co‐occurrence (the coexistence of two or more species in a single tree) was more frequent in control plots, where lianas were present, versus removal plots. Forest stand age had a larger effect on ant community structure than the presence of lianas. Mean ant species richness in a forest plot increased by ca. 10% with increasing forest age across the 31‐year chronosequence. Ant surveys from forest >20 years old included more canopy specialists and fewer ground‐nesting ant species versus those from forests <20 years old. Consequently, lianas had a minimal effect on arboreal ant communities in this early successional forest, where rapidly changing tree community structure was more important to ant species richness and composition.     

Carbon Accumulation Patterns During Post-Fire Succession in Cajander Larch (Larix cajanderi) Forests of Siberia

Increased fire activity within boreal forests could affect global terrestrial carbon (C) stocks by decreasing stand age or altering tree recruitment, leading to patterns of forest regrowth that differ from those of pre-fire stands. To improve our understanding of post-fire C accumulation patterns within boreal forests, we evaluated above- and belowground C pools within 17 Cajander larch (Larix cajanderi) stands of northeastern Siberia that varied in both years since fire and stand density. Early-successional stands (<20-year old) exhibited low larch recruitment, and consequently, low density, aboveground larch biomass, and aboveground net primary productivity (ANPP_tree). Mid-successional stands (21- to 70-year old) were even-aged with considerable variability in stand density. High-density mid-successional stands had 21 times faster rates of ANPP_tree than low-density stands (252 vs. 12?g?C?m^?2?y^?1) and 26 times more C in aboveground larch biomass (2,186 vs. 85?g?C?m^?2). Density had little effect on total soil C pools. During late-succession (>70-year old), aboveground larch biomass, ANPP_tree, and soil organic layer C pools increased with stand age. These stands were low density and multi-aged, containing both mature trees and new recruits. The rapid accumulation of aboveground larch biomass in high-density, mid-successional stands allowed them to obtain C stocks similar to those in much older low-density stands (~8,000?g?C?m^?2). If fire frequency increases without altering stand density, landscape-level C storage could decline, but if larch density also increases, large aboveground C pools within high-density stands could compensate for a shorter successional cycle.     

Sapling communities in Amazonian white-water forests

Aim Structure and floristic composition of forest regeneration (trees between 1 and 10 cm diameter at breast height (d.b.h), ≥ 1 m growth height) was described in three forest types of Amazonian white‐water forests (várzea), in order to analyse whether floristic composition of saplings is related to the successional stage of the forests, whether it differs in comparision with the mature flora, and if there exists a zonation of sapling species along the gradients of flooding and irradiation. Location Mamirauá Sustainable Development Reserve, Western Brazilian Amazon. Methods The investigated forests were of the low and the high várzea type, on an annual average flooded around 4 and 1 months, respectively. The two low‐várzea forests belonged to the secondary and to the late‐successional stage, the high‐várzea forest also to the late‐successional stage. A total of 24 circular sample plots covering 1885 m² were installed. They were nested within three rectangular 1 ha permanent sample plots where individuals ≥ 10 cm d.b.h. were formerly inventoried. Average inundation and radiation [relative photosynthetically active radiation (rPAR)] at the forest floor was recorded in all inventoried plots. The Mean spatial Distribution Center (MDC; Ebdon, 1998 ) for all sapling species was calculated. Sapling species were grouped into associations with respect to their light‐demand and their location along the flood‐level gradient. Results Average flood height and average rPAR at the forest floor was highest in the secondary stage of the low várzea and lowest in the high‐várzea forest. Overall average density and basal area of the saplings averaged 2250 individuals and 2.3 m² ha^?1 in the secondary stage, 2330 individuals and 2.6 m² ha^?1 in the late‐successional stage of the low várzea and 5000 individuals and 4.8 m² ha^?1 in the high várzea. In all forest types, species richness of saplings was lower than species richness of trees ≥ 10 cm d.b.h., and amounted to 25 species in the secondary stage, to 35 species in the late‐successional stage of the low várzea and to 88 species in the high‐várzea forest. The amount of ‘immigrants’ ( Bazzaz, 1991 ) at the sapling level increased with proceeding forest succession and amounted to 24 and 29% in the low várzea and to 31% in the high várzea. Sapling species distribution, species richness and individual density was linked to both, the gradient of flooding and the gradient of irradiation. Species richness and individual density was highest in the high várzea and decreased with increasing influence of flooding. The high várzea was predominated by pronounced shade‐tolerant sapling species, whereas in the low várzea occured both, light demanding and shade‐tolerant species groups. Main conclusions Influence of flooding seems to be the main factor triggering species composition and structure of sapling communities in várzea forests. Proceeding forest succession reduces the impact of flooding because of the biogenical induced silting up of the forested sites. However, forest succession also alters forest architecture of the overstory and such the light conditions at the sapling level. Therefore, radiation is an important factor influencing species composition of sapling communities in várzea forests.     

Underplanting degraded exotic Pinus with indigenous conifers assists forest restoration

We propose that nonharvest plantations could provide important opportunities for restoration of indigenous forest cover and related ecosystem services. We assessed the relative performance of three Podocarpaceae (podocarps) species planted into a degraded Ponderosa Pine (Pinus ponderosa) plantation, central North Island, New Zealand. We hypothesised that the degraded pine plantation overstorey could provide suitable conditions for the development of a podocarp‐dominated forest structure within ca. 50 years of underplanting and that podocarp growth would differ depending on the species suitability to the site. Rimu (Dacrydium cupressinum) significantly outperformed both Totara (Podocarpus totara) and Kahikatea (Dacrycarpus dacrydioides) in height and diameter growth. Rimu was now the structurally dominant tree where it occurred rather than pine. Per annum scaled carbon storage within Rimu stands was significantly greater than the Totara, Kahikatea or Pine stands. All podocarp species had attained a greater stand density compared to the pine overstorey. Possible reasons for the differing podocarp growth performance include different light requirements, response to soil nutrients, elevational distributions and frost susceptibility. There were significant differences in understorey species richness among the different stands of podocarp species. Underplanting accelerated successional development by incorporating late‐successional indigenous canopy dominants within the forest succession and overcame limitations imposed on forest succession at the site from its isolation from indigenous forest tree seed sources.     

Landscape Patterns of Sapling Density,Leaf Area,and Aboveground Net Primary Production in Postfire Lodgepole Pine Forests,Yellowstone National Park (USA)

Causes and implications of spatial variability in postfire tree density and understory plant cover for patterns of aboveground net primary production (ANPP) and leaf area index (LAI) were examined in ninety 11-year-old lodgepole pine (Pinus contorta var. latifolia Engelm.) stands across the landscape of Yellowstone National Park (YNP), Wyoming, USA. Field studies and aerial photography were used to address three questions: (1) What is the range and spatial pattern of lodgepole pine sapling density across the burned Yellowstone landscape and what factors best explain this variability? (2) How do ANPP and LAI vary across the landscape and is their variation explained by abiotic factors, sapling density, or both? (3) What is the predicted spatial pattern of ANPP and LAI across the burned Yellowstone landscape? Stand density spanned six orders of magnitude, ranging from zero to 535,000 saplings ha^?1, and it decreased with increasing elevation and with increasing distance from unburned forest (r ²?=?0.37). Postfire densities mapped from 1:30,000 aerial photography revealed that 66% of the burned area had densities less than 5000 saplings ha^?1 and approximately 25% had densities greater than 10,000 saplings ha^?1; stand density varied spatially in a fine-grained mosaic. New allometric equations were developed to predict aboveground biomass, ANPP, and LAI of lodgepole pine saplings and the 25 most common herbaceous and shrub species in the burned forests. These allometrics were then used with field data on sapling size, sapling density, and percent cover of graminoid, forb, and shrub species to compute stand-level ANPP and LAI. Total ANPP averaged 2.8 Mg ha^?1y^?1 but ranged from 0.04 to 15.12 Mg ha^?1y^?1. Total LAI averaged 0.80 m² m^?2 and ranged from 0.01 to 6.87 m² m^?2. Variation in ANPP and LAI was explained by both sapling density and abiotic factors (elevation and soil class) (ANOVA, r ²?=?0.80); abiotic variables explained 51%–54% of this variation. The proportion of total ANPP contributed by herbaceous plants and shrubs declined sharply with increasing sapling density (r ²?=?0.72) and increased with elevation (r ²?=?0.36). However, total herbaceous productivity was always less than 2.7 Mg ha^?1 y^?1, and herbaceous productivity did not compensate for tree production when trees were sparse. When extrapolated to the landscape, 68% of the burned landscape was characterized by ANPP values less than 2.0 Mg ha^?1y^?1, 22% by values ranging from 2 to 4 Mg ha^?1y^?1, and the remaining 10% by values greater than 4 Mg ha^?1y^?1. The spatial patterns of ANPP and LAI were less heterogeneous than patterns of sapling density but still showed fine-grained variation in rates. For some ecosystem processes, postfire spatial heterogeneity within a successional stage may be similar in magnitude to the temporal variation observed through succession.