Natural Secondary Forest Research Articles

Effect of forest vegetation on runoff and sediment production in sloping lands of Loess area

According to fixed-position data for 1985–2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County of Shanxi Province in Loess area, this paper studied the relationship between vegetation and runoff and sediment production in sloping lands in detail, which helps to provide scientific basis for vegetation re-construction and studies on environmental transformation of water and sediment in watersheds of Loess area. Although, many study results testify that forest vegetation has an important function in soil and water conservation and cutting runoff, the effect of vegetation on runoff and sediment transmission is complicated, and this needs to be studied in depth. The results of the paper showed the following. Firstly, the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest, and runoff and sediment produced in the former in individual rainfall were 65%–82% and 23%–92% of those produced in the latter. At the same time, better correlative relationship between runoff and sediment production and rainfall and rainfall intensity were testified by multiple regression, but the correlation decreased gradually with the increase of canopy density of forest. Secondly, the difference of runoff and sediment production in several land use types was very distinct, and the amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least, and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O. davidiana forest. Besides, runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than those of O. davidiana forest, respectively, but the amount decreased obviously after high-standard soil preparation in the case of the former. Thirdly, based on gray cognate analyses of factors affecting runoff and sediment production in sloping land, the factors of stand canopy density and herb and litter biomass were the most significant ones, whose gray incidence degree exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of Loess area, which will help to increase coverage and litter thickness in order to cut down the runoff and sediment dramatically in sloping land.

Carbon storage of artificial forests in rehabilitated lands in the upper reaches of the Yellow River

We studied 10-to 27-year-old artificial forests on rehabilitated lands in the upper reaches of the Yellow River with the objective of comparing the carbon densities of various artificial and natural forests. Under artificial plantations, the vegetation layer (including roots) had a mean carbon density of 111.3 t/hm2, the litter layer a density of 5.1 t/hm2, and the soil layer a density of 64.9 t/hm2. These values accounted for 28.6%, 13.8%, and 61.0% of their respective counterparts in the natural secondary forests under the same site conditions in the region. The ratios of carbon density among vegetation, litter, and soil pools were 39.6:1.8:58.6 for artificial forests and 57.4:2.7:39.9 for natural forests. The carbon densities of the vegetation and litter layers increased exponentially with forest age. The total carbon density ratios were also increasing gradually. Although the mean total carbon density of the artificial forests in the rehabilitated lands was 281.2 t/hm2 in the experimental area, it accounted for only 41.5% of the carbon density of the natural secondary forests (677.4 t/hm2). The annual increase in total carbon density of artificial forests was as high as 15.2 t/hm2, which was 11.7% more than that of natural forests and 6.8 times higher than that (1.95 t/hm) of artificial forests in the entire country as measured during 1994–1998. This indicates that growth and carbon storage capacity of artificial forests in the rehabilitated lands were higher than those of forests on the barren hills and the secondary forests. We concluded that the conversion project from croplands to forests and grasslands based on scientific principles is very important in the formation of carbon sinks for reducing greenhouse effects.

Mid- and near-infrared spectroscopic assessment of soil compositional parameters and structural indices in two Ferralsols

Bulk soil samples (BS) ( n = 120) from long-term tillage experiments and areas covered by secondary natural forest were collected in the Brazilian savanna region (Cerrado) at Santo Antônio de Goiás, and southern Atlantic forest region at Londrina. Bulk soils were separated into 8 aggregate size fractions (ASF) by wet sieving ( n = 700). Bulk soil samples (BS) and ASF were analyzed for total C, N by dry combustion. BS were also analyzed for sand, silt, and clay by densitometry, and several measures of soil aggregation were determined. All samples were scanned in the mid- and near-infrared (Mid-IR, NIR) by diffuse reflectance of ground, non-KBr diluted samples using a Digilab FTS-7000 FTIR spectrometer equipped with a Pike Auto-Diff auto-sampler. Quantitative calibrations for the various analytes were performed separately for the original set of 120 BS samples and the set of 700 ASF samples using partial least squares regression (PLSR). Results for the set of 120 BS for total C and N were excellent using either spectral range with R 2 > 0.97, except for C by Mid-IR ( R 2 = 0.93). Similar results were obtained for determinations of sand and clay ( R 2 > 0.94). Silt, determined by difference (100% − %sand − %clay), gave much lower R 2 (0.80 and 0.63 for Mid-IR and NIR, respectively). For aggregation indices, R 2 of ∼ 0.80 were achieved in the Mid-IR, NIR results were not as good ( R 2 < 0.67). Efforts with the 700 ASF samples resulted in R 2 of 0.98 and 0.96 for C, and 0.96 and 0.97 for N, for Mid-IR and NIR calibrations, respectively. Calibration efforts to determine the values for the set of 700 ASF samples using set of 120 BS from which they were fractionated gave R 2 = 0.90 and 0.87 in the Mid-IR and NIR, respectively, when 5% of the ASF were added to the set of 120 BS. Spectral discrimination of sample source was easily and very accurately determined for all data sets examined.

Effects of regenerating forest cover on soil microbial communities: A case study in hilly red soil region, Southern China

The stability and function of a soil ecosystem depends on the cycling of nutrients by the soil microbial community. To evaluate the effects of regenerating forest cover on the function of microbial community, the differences of four forest restoration approaches, including plantations of slash pine, Chinese fir, tea-oil camellia and natural secondary forest, in soil microbial community size, activity and metabolic diversity were measured by microbial biomass and metabolic diversity (BIOLOG) assays in a hilly red soil region, Southern China. Native soils were sampled and assessed with 0–20 and 20–40 cm layers. Results showed that significant differences ( p < 0.05) were found in soil microbial biomass among four forest restoration approaches. It was highest in the soil of natural secondary forest, medial in the plantations of tea-oil camellia and Chinese fir and the least in slash pine plantation. Principal component analysis (PCA) further revealed consistent differences of the metabolic diversity patterns in 0–20 cm soil, but not for Chinese fir plantation, tea-oil camellia plantation and natural secondary forest in 20–40 cm soil. Average well colour development (AWCD) and indices of richness and diversity showed significant difference in the four forest restoration approaches. The variable tendency of the indicators was the same as microbial biomass. These suggested that the ability to utilize sole-carbon-source and functional diversity (metabolic diversity) for soil microbial community were stronger in natural secondary forest than that in plantations. Altogether, microbial biomass and metabolic diversity patterns in 0–20 cm soil of natural secondary forest were dominant, comparing with that of three plantations, viz. slash pine plantation, Chinese fir plantation and tea-oil camellia plantation. While in 20–40 cm soil there were no recognizable differences for above indicators among four vegetation types. Factors affecting the structure and function of soil microbial community appeared to be linked closely with artificial tending, soil and water loss, root biomass and litter production. The information gathered from the studies can be used to baseline data for forest restoration projects.

How different reforestation approaches affect red soil properties in southern China

AbstractSignificant differences were found in soil physicochemical and biological effects between various forest restoration approaches of a hilly red‐soil region, southern China. Soil quality was the highest in natural secondary forest (0·95), while in sites revegetated with tea‐oil camellia (Camellia oleifera), Chinese fir (Cunninghamia lanceolata) and slash pine (Pinus elliottii) and control sites, integrated soil quality indices were 0·68, 0·55, 0·36 and 0·04 respectively. The lower soil quality of plantations and controls resulted from increased disruption of soil physical structure, lower quality litter fall, lower litter fall production, reduction in microbial biomass, decline of microbial function and loss of soil nutrients due to periodically artificial tending and accelerated soil erosion. Improvement in soil physicochemical properties and enhanced soil microbial function at a natural secondary forest site demonstrated the inherent restoration of these soils. Hence, natural restoration, as well as reducing human disturbance, is a better approach to improving soil properties than returning farmland to planted woodlands. Copyright © 2005 John Wiley &amp; Sons, Ltd.

The applicability of a color acetate film for estimating photosynthetic photon flux density in a forest understory

The suitability of a color acetate film for estimating photosynthetic photon flux density (PPFD) in a forest understory was examined. The fading ratio of the film (F), the total PPFD (PPFDtotal) to which the film was exposed, and the average daily maximum temperature during exposure (T) were obtained from measurements at multiple sampling points throughout an entire year within a natural secondary forest (n = 42). The ranges of the recorded values were as follows: F 35%–99%, PPFDtotal 1.4–28.3 mol m−2, and T 6°–32°C. PPFDtotal was regressed by F and T with a high r2 (=0.94; P < 0.0001): PPFDtotal = (100 − F)/(1.085 + 0.051 T). The absolute error (|estimated PPFDtotal − measured PPFDtotal|) averaged 1.3 mol m−2 with a maximum of 5.7 mol m−2, indicating a good fit. These results indicated broad applicability of the film, both spatially and temporally, for estimating forest understory PPFD.

Natural regeneration in exotic tree plantations in Hong Kong, China

Tree plantations consisting mostly of a single exotic species have been established in Hong Kong, South China, for reforesting degraded lands since the 1950s. In this study, natural woody plant regeneration success under different types of closed-canopy plantations ( Acacia confusa, Lophostemon confertus, Melaleuca quinquenervia and mixed-plantings) and natural secondary forests in the central New Territories were assessed. A total of 79 tree species, 64 shrubs and 23 woody climbers were recorded in 16 20 m × 20 m plantation plots. Stem density of woody plant regeneration was similar among all sites, ranging from 9031 to 10,950 stems > 0.5 m in height per hectare. Multivariate analysis of understorey species composition showed that there were consistent differences between plantation types. Lophostemon plantations generally had poor native plant colonization in comparison with natural secondary forests and other types of plantations. These differences between forest types can be at least partly attributed to pre-existing site conditions, since the tree species planted were matched to the site. Native woody plant colonization was poor on sites isolated from natural seed sources. Plantation understories were generally dominated by a few species of bird-dispersed shrubs, suggesting that enrichment planting with poorly dispersed shade-tolerant native tree species will be needed to facilitate regeneration in those plantations where natural regeneration is inadequate.

Community Characteristics of Early Recovery Vegetation on Abandoned Lands of Shifting Cultivation in Bawangling of Hainan Island, South China

Abstract: Shifting cultivation is a major form of agricultural practice in most parts of tropical regions worldwide. In places where the bush fallow period is excessively shortened or the period of cultivation is extended for too long, the rate of vegetation recovery and biodiversity on abandoned lands of shifting cultivation would decline. The recovery of the secondary plant communities could even be inhibited for a prolonged period because of grass occupancy. Because of the vital significance of the early recovery communities to secondary succession, we studied the community characteristics of early recovery vegetation on abandoned lands of shifting cultivation in Bawangling of Hainan Island. Measurements were made of the community composition and structure of early recovery vegetation. The sprouting abilities of different functional groups and different species in the same functional group, and the effect of the grass functional group on the composition and quantitative characteristics of tree and shrub functional groups were analyzed. Results indicated that only a few families, genera, or species apparently dominated in the early recovery vegetation on the abandoned lands of shifting cultivation and that deciduous species occurred with a rather high percentage in this early recovery community compared with the natural secondary or old growth forests. Small-sized individuals dominated the woody community. The abundance and basal area of sprouting stems for species in the tree functional group were greater than those of seeder stems, whereas the abundance and basal area of resprouters and seeders for species in the shrub functional group did not differ. The total abundance of stems for the community, stem abundances for species in tree or shrub functional groups, and for seeder or resprouter stems were all negatively correlated with coverage of the grass functional group. The mean sprouting ability in the tree functional group was greater than in the shrub functional group. The sprouting ability for different species in the same functional group was also significantly different. (Managing editor: Ya-Qin HAN)(Recommended by: Jian-Xin SUN)

Landscape pattern and fragmentation of natural secondary forests in the eastern mountainous region, northeast China: A case study of Mao'ershan forests in Heilongjiang Province

Mao’ershan region is a representative natural secondary forested region in the eastern mountainous region, northeast of China. Under the support of ARC/INFO, the landscape pattern and landscape diversity of Mao’ershan region were studied by combining the forest type map (1:10000), which was drawn from the aerial photograph (1999), field investigation and land utilization, map (1:10000). The selected indices included patch number, patch size, patch density index, richness index, domonance index, evenness index and diversity index. The results showed that the landscape dominant forest type in Mao’ershan region was softwood broad-leaved forest. In all landscape types,the average patch area of natural secondary forests was bigger than that of artificial forest. The patch density index of each landscape formed in artificial forest was higher than that of natural secondary forest. The landscape diversity index and landscape evenness index of natural forest were highest, the landscape heterogeneity was also, but the landscape dominance was lower. In natural forest, the control effects of landscape elements on landscape-structure, function and its change were weakened. The artificial forest was on the contrary.

DISSOLVED ORGANIC CARBON CONCENTRATIONS IN SOIL UNDER DIFFERENT LAND USES IN THE LIUPAN MOUNTAIN FOREST ZONE

Dissolved organic carbon is an important component of the carbon balance of terrestrial ecosystems and source of energy, carbon, and nutrient transfer from terrestrial to aquatic ecosystems. Land use changes caused by human activities have had major impacts on terrestrial ecosystem carbon cycles, including impacts of soil DOC dynamics. Hence, it is important to understand the impacts of land use changes on DOC for assessing the impacts of land use change on the carbon cycle. Over the last several centuries, extensive areas of native vegetation in the Liupan Mountain Forest Zone have been replaced by croplands or rangelands, whereas in recent decades former arable lands and rangelands have been afforested. However, the impacts of these land-use changes on the terrestrial ecosystem carbon cycle are unclear, especially on the soil DOC dynamics. In order to assess the impacts of land-use changes on soil DOC dynamics, we measured the concentrations of DOC in precipitation, subsurface water, soil leachate, detrital leachate solutions, throughfall, and water percolating through the soil in plots with the same elevation, exposure, and soil types but with different vegetation types. A natural secondary forest dominated by Querces liaotungensis, Populus davidiana, or brushwood, a cropland and rangeland derived from destruction of the natural secondary forests, and a 13, 18 and 25 year old larch plantation, Larix ricipis-rupprechtii, afforested on former croplands or rangelands were studied. Our results showed that concentrations of DOC in precipitation and subsurface water from May to October was 0.80-1.60 mg·L~(-1) and 2.43-7.66 mg·L~(-1), respectively. From September to October, the concentration of DOC in throughfall was 1.78-15.20 mg·L~(-1) which was higher under natural forests or plantations than in croplands or rangelands and positively correlated with annual production of aboveground detritus (p=0.05). The concentration of DOC in detrital leachate solutions, derived from detritus submerged in water for 24 h, was 12.30-64.79 mg·L~(-1) and its fraction was not more than 1%. The concentration of detrital DOC was 400% and 153% higher under natural forests than cropland and rangeland, respectively, and 194% and 50% higher under plantation than cropland and rangeland, respectively. Its fraction was 79% and 98% higher in the cropland and rangeland than the natural forest, respectively, and 180% and 210% higher in the cropland and rangeland than the plantation, respectively. The concentration of DOC in detrital leachate was positively correlated with aboveground detrital carbon storage of leaf, branch, humus and litter (p=0.05, n=184). The concentration of DOC in soil solutions in the 0-20 cm deep soil layer was 7.88-88.44 mg·L~(-1) and its fraction was not more than 1%. The concentration of soil solution DOC was higher under the natural secondary forest or the plantation than cropland or rangeland, and its fraction was lower under natural forest than cropland or rangeland but higher under the plantation than natural secondary forests. The difference of the soil solution DOC concentration or fraction between the natural secondary forest or plantation and rangeland or cropland was greater at 0-10 cm soil depth than 10-20 cm soil layer. The change of this DOC concentration with soil depth was greater under the natural secondary forest or plantation than cropland or rangeland. The concentration of this DOC was positively correlated with detrital carbon storage and soil water content (p=0.05), and soil water content was the main factor that influenced the concentration of DOC in soil solutions. The concentration of DOC in soil percolation water was 5.76-58.84 mg·L~(-1) which was higher under the natural forest or plantation than cropland or rangeland. The difference in this DOC concentration between the natural secondary forest or plantation and rangeland or cropland was greater in the 0-10 cm than 10-40 cm soil layer. The change of this DOC concentration with soil depth was greater under the natural secondary forest or plantation than cropland or rangeland. These differences were ascribed to the differences in vegetation and soil properties that resulted from changes in land use and their consequent impacts on hydrological processes. The results of this study indicate that changes in land use have large impacts on terrestrial DOC concentrations.

Diversity and community structure of geometrid moths of disturbed habitat in a montane area in the Ecuadorian Andes

The diversity and faunal composition of geometrid moths (Lepidoptera: Geometridae) was investigated at two sites within an anthropogenically disturbed habitat mosaic at 1950 m and 2005 m a.s.l., in the vicinity of intact Andean montane rainforest in southern Ecuador. A total of 629 specimens belonging to 197 species were collected. The results were compared with those from ten sites of undisturbed forest habitats within an elevational range of 1800-2212 m. The local diversity of the moths at disturbed sites was surprisingly high (Fisher's alpha: 86.1 and 86.8; rarefied species number at the level of 250 specimens: 117 and 113; extrapolated species number, estimator Chao 1: 220 and 303). Forest successions and remnants probably serve as habitats for many species, but diversity is possibly overestimated due to the presence of 'tourist species' from adjacent forests. Disturbed habitats were characterized by a low diversity in the genera Eois, Bonatea and Herbita, probably due to the absence of their potential host plants (e.g. Piper species). Only three moth species represented by more than three individuals were found exclusively in disturbed habitats (Eupithecia densicauda, Pero obtusaria, 'Sabulodes' muscistrigata). Some 25 species profited from disturbance, among these were six species of the genus Eupithecia. The proportion of species present with only one specimen was high (56 and 62%), and species dominance was low (Berger- Parker index: 7.9 and 5.8%). In two-dimensional scaling based on the CNESS index of dissimilarity, disturbed sites are separated from the forest sites. The conservation of secondary forest remnants and natural forest appears to be essential for the survival of the very species-rich Andean geometrid moth communities.

Effects of Land Use on Bird Species Richness in Sulawesi, Indonesia

Abstract: There is still much debate over the potential value of land‐use systems for the maintenance of tropical biodiversity. An increasing number of studies indicate that much forest biodiversity can also be found in the agricultural landscape matrix. Because there is little information on the potential value of land‐use systems for tropical forest bird species, we conducted repeated point counts in near‐primary forest, adjacent young secondary forest, modernized cacao agroforestry systems, and annual cultures at submontane elevations in central Sulawesi, Indonesia. Species richness decreased from natural forest and young secondary forest to agroforestry systems and annual cultures. Although species richness was similar between natural and young secondary forest, the number of endemic bird species was significantly lower in second‐growth forest. Species composition gradually changed as the habitat changed from natural to secondary forest, agroforestry systems, and annual cultures. Despite close proximity to near‐primary forest, the agroforestry systems studied supported only a few small frugivorous‐nectarivorous species. Our results suggest that secondary forest could play an important role in the conservation of many Sulawesi bird species, but, although suitable for colonization, its potential to sustain populations over the long term is unknown. Improvement of the landscape matrix for biodiversity conservation through secondary habitats therefore seems desirable to enlarge the ranges of forest species, but the fight against land conversion within protected areas of the region should be of much higher importance, at least at present.

Landscape pattern and diversity of natural secondary forests in the eastern mountainous region, northeast China: A case study of Mao’ershan region in Heilongjiang Province

Landscape pattern and diversity of natural secondary forests in the eastern mountainous region, northeast China: A case study of Mao’ershan region in Heilongjiang Province

Effects of closing mountain for forest restoration in the watershed of Miyun reservoir, Beijing

The paper provides a systematical analysis of ecological restoration effects of natural secondary forest of closure area in Chao Guanxi Gou, Miyun County, Beijing. The results indicate that through more than twenty years of hillclosing afforestation since 1983, canopy closure has improved almost by 0.2; forest cover rate has raised from 7.2% to 93.8%; biodiversity, tree biomass and vegetation community have increased to a great extent. Compared with the average canopy closure before hillclosing afforestation in this area, it has improved to over 0.4 in average and increased by 0.1-0.2. The forest coverage degree has reached more than 90%. Consequently, the forest plays more important roles in intercepting precipitation, improving water storage capacity of soil, decreasing the surface runoff, and preventing soil and water loss.

Composition and characteristics of natural secondary forests in Shenzhen, South China

The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea + Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, i.e., Schefflera, Sterculia and Cleistocalyx + Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04–2.953 and 64.2%–74% respectively, but those of the Endospermum community are 4.74 and 79% respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.

Spatial connectivity and distribution of landscape type in the natural secondary forests of eastern mountainous region, northeast China—a case study of Mao'ershan region in Heilongjiang Province

Mao'ershan region is representative in the natural secondary forested region of the eastern mountainous region, northeast China. The landscape nearest neighbor index and landscape connectivity index were calculated with ARC/INFO software for Mao'ershan region. The spatial distribution of the landscape of the region was analyzed. The results showed that the landscape connectivity index of non-woodland was significantly higher than that of woodland. The landscape connectivity index of natural forest was nearly equal to zero, which means its fragmentation degree is high. The nearest neighbor index of plantation was lower than that of natural forest and non-forestland. Among the man-made forests, the distance index of the coniferous mixed plantation is the lowest, and its pattern is nearly glomeration. The landscape pattern of natural forest presented nearly random distribution. Among non-forest land, the distance index of cut blank was the lowest, and its pattern was also nearly glomeration.

SOIL QUALITY CHANGES FOLLOWING FOREST CLEARANCE IN BENGKULU, SUMATRA

Intense destruction and degradation of tropical forests is recognized as one of the environmental threats and tragedies. These have increased the need to assess the effects of subsequent land-use following forest extraction on soil quality. Therefore, the objective of this study is to evaluate the impacts of land-use type on soil quality properties in Bengkulu Province, Sumatra. Soil samples were collected from adjacent sites including natural secondary forest, bare land, cultivated land and grassland. The results show that land-use following forest clearance lowered saturated hydraulic conductivity (85%), porosity (10.50%), soil water content at field capacity (34%),C organic (27%), N total (26%), inorganic N (37%), soil microbial biomass C (32%), mineralizable C (22%), and particulate organic matter (50%), but slightly increased water soluble organic C. Specific respiration activity rates increased about 14% in cultivated soils compared to natural forest soils, indicating greater C turnover per labile C pool in the form of soil microbial biomass, thus decreased biologically active soil organic matter. Forest conversion tends to reduce the C,ffg/Crer for all deforested sites. All of deforested areas relatively have infertile soil, with the worst case found in cultivated field. The C^g/Crd of cultivated fields was about 24% less than that of remnant forest (1.07). Grassland apparently maintains only slightly higher soil C levels than the bare land. On average, degradation index of soil following forest clearance was 35% with the highest deterioration occurred in the bare land (38%). Fallowing the fields by naturally growth of Imperata cylindrica for about 15 yr in abandoned land after 3-5 years of cultivation did not improve the soil quality. Moreover, forest clearance has an impact on soil quality as resulted in the loss of a physically protected organic matter and reduction in some labile C pools, thus declined biological activity at disturbed ecosystems. Keywords: Degradation index / forest / Imperata cylindrica grassland / soil quality/ soil organic matter

Dynamic change of arborous species diversity in natural secondary forests after selective cutting on the north slope of Changbai Mountain, Northeast China

The community characteristics of natural secondary forests on the north slope of Changbai Mountain after selective cutting were investigated, and the dynamics of arborous species diversity during the restoration period of 28 years were studied. The results showed that the arborous species richness (S) had little change and kept the range of 18–22 all along, the Simpson index (D) of the secondary layer and regeneration layer and whole stand had similar trends of change, but that of the canopy layer descended slowly in initial 15 years and had little change later, and the change of diversity index was not obvious and the Shannon-Wiener index (H’) fluctuated in a very small scopes (H’±10%).

Convergence Between Dung Beetle Assemblages of a Post‐Mining Vegetational Chronosequence and Unmined Dune Forest

Abstract In Maputaland, South Africa vegetative and microclimatic changes on mined dunes drive the composition of the dung beetle fauna toward convergence with that in natural dune forest on unmined dunes. We assessed the pattern of these changes using a 23‐year vegetational chronosequence on mined dunes, which passes from grassland (approximately 1 year) to open Acacia shrubland thicket to Acacia karroo‐dominated woodland (approximately 9 years). Across this sequence, which represents successional stages in the restoration of dune forest, there was a sequential trend toward convergence in dung beetle species composition in both the entire species complement and, particularly, in shade specialist species. However, species abundance patterns showed a trend toward convergence only in early chronosequence Acacia woodland, followed by a decline in similarity between dung beetle assemblages of older Acacia woodland and unmined natural forest. This trend toward divergence was common both to the entire species complement, which includes widespread taxa, and to species endemic to Maputaland or the east coast. These trends in similarity and dissimilarity between dung beetle assemblages closely parallel the greater physiognomic and microclimatic similarity between early Acacia woodland and natural forest and the relative dissimilarity of older Acacia woodland. In conclusion, although percentage similarities between dung beetle assemblages of approximately 12‐year woodland and natural forests were comparable with those between each natural forest stand, decline in similarity in older woodland stands suggests that lasting convergence in dung beetle species abundance will only be attained once the Acacia woodland is replaced by secondary natural forest.

The solute budget of a forest catchment and solute fluxes within a Pinus radiata and a secondary native forest site, southern Chile

AbstractSolute concentrations and fluxes in rainfall, throughfall and stemflow in two forest types, and stream flow in a 90 ha catchment in southern Chile (39°44′S, 73°10′W) were measured. Bulk precipitation pH was 6·1 and conductivity was low. Cation concentrations in rainfall were low (0·58 mg Ca2+ l−1, 0·13 mg K+ l−1, 0·11 mg Mg2+ l−1 and &lt;0·08 mg NH4–N l−1), except for sodium (1·10 mg l−1). Unexpected high levels of nitrate deposition in rainfall (mean concentration 0·38 mg NO3–N l−1, total flux 6·3 kg NO3–N ha−1) were measured. Concentrations of soluble phosphorous in bulk precipitation and stream flow were below detection limits (&lt;0·09 mg l−1) for all events. Stream‐flow pH was 6·3 and conductivity was 28·3 μs. Stream‐water chemistry was also dominated by sodium (2·70 mg l−1) followed by Ca, Mg and K (1·31, 0·70 and 0·36 mg l−1). The solute budget indicated a net loss of 3·8 kg Na+ ha−1 year−1, 5·4 kg Mg2+ ha−1 year−1, 1·5 kg Ca2+ ha−1 year−1 and 0·9 kg K+ ha−1 year−1, while 4·9 kg NO3–N ha−1 year−1 was retained by the ecosystem. Stream water is not suitable for domestic use owing to high manganese and, especially, iron concentrations.Throughfall and stemflow chemistry at a pine stand (Pinus radiata D. Don) and a native forest site (Siempreverde type), both located within the catchment, were compared. Nitrate fluxes within both forest sites were similar (1·3 kg NO3–N ha−1 year−1 as throughfall). Cation fluxes in net rainfall (throughfall plus stemflow) at the pine stand generally were higher (34·8 kg Na+ ha−1 year−1, 21·5 kg K+ ha−1 year−1, 5·1 kg Mg2+ ha−1 year−1) compared with the secondary native forest site (24·7 kg Na+ ha−1 year−1, 18·9 kg K+ ha−1 year−1 and 4·4 kg Mg2+ ha−1 year−1). However, calcium deposition beneath the native forest stand was higher (15·9 kg Ca2+ ha−1 year−1) compared with the pine stand (12·6 kg Ca2+ ha−1 year−1). Copyright © 2002 John Wiley &amp; Sons, Ltd.