Undisturbed Forest Sites Research Articles

Regeneration of post‐mining and post‐fire soil function by assessment of tree nutrient status: Evidence from pioneer and N‐fixing species

AbstractNutrient concentrations in the foliage of particular tree species can identify growth‐limiting factors. Therefore, the adaptability and usefulness of certain trees in the afforestation of barren soils after disturbances could be based on nutrient supply and stoichiometry. In this study, we investigated the macronutrient supply to (i.e., nitrogen [N], phosphorus [P], potassium, sulfur, calcium [Ca], and magnesium [Mg]) and C:N:P (carbon:nitrogen:phosphorus) stoichiometry of the foliage of black alder (Alnus glutinosa), common birch (Betula pendula), and Scots pine (Pinus sylvestris) in two different regeneration scenarios—a reclaimed mine site with primary succession and an afforested post‐fire (PF) site with secondary succession. The control plot was on an undisturbed forest site hosting stands of the studied tree species. The lower concentrations of elements in the post‐mining soils developed from “point zero” were enough to supply the trees with a similar level of nutrition to those in the PF and undisturbed soils. The studied tree species differed in their foliage chemistry and had different effects on the soil properties. The alder and birch foliage contained more nutrients than the pine foliage. In particular, the birch foliage contained the highest concentrations of Ca, Mg, and P, thus enhancing the biogeochemical cycling of these elements. The alder foliage had the highest N concentration, albeit the soil total N contents under this species were not higher than those under birch. Thus, its phytomeliorative effect may have been overestimated. The pine foliage contained the lowest concentrations of nutrients, indicating the high nutrient use efficiency of this species. On the sites degraded after disturbance, pine and birch grew under N‐limitation stress, while the alder—a N‐fixing species—grew under P‐limitation stress, especially at the PF site. The PF soils under alder were also characterized by higher acidity, P depletion, and higher C:P and N:P ratios compared to the PF soils under the other studied species. We found that birch should be the most common tree species in the first phase of area regeneration after disturbances. Introducing alder into afforestation should take place in admixtures, especially at the PF site.

Trends in groundberry cover under climate change in the southern and central Yukon, 1997–2022

Groundberries are an important component of the flora of the boreal forest and provide seasonally important food for many birds and mammals, as well as local people in northern Canada. Here, we ask whether there has been a change in the cover of groundberries in the Yukon boreal forest over the last two decades. We monitored five common species at undisturbed forest sites spaced 300 km apart. At our Kluane site, we monitored 710 fixed quadrats per year for 26 years (1997–2022), and at Mayo 500 quadrats per year for 18 years (2005–2022). The cover of four species, Arctostaphylos uva-ursi (L.) Spreng. (bearberry) , Arctostaphylos rubra (Rehder & E.H. Wilson) Fernald (red bearberry) , Empetrum nigrum L. (crowberry), and Geocaulon lividum (Richardson) Fernald (toadflax), declined annually by 0.2%–0.8% at both sites. In contrast, Vaccinium vitis-idaea L. (lingonberry) increased annually by 0.5% and 0.8%. We tested whether increases in summer temperature and rainfall were correlated with the observed changes but found no significant relationships. These boreal plants are changing in abundance, but we have limited data on the extent and speed of these changes. We recommend experiments to understand the cause(s) of these changes in groundberry productivity. Our study is a start in monitoring important berry species in this critical ecosystem of northern Canada.

Differences in genetic diversity and reproductive performance of a moss, a leafy liverwort, and a thalloid liverwort from forests of contrasting ages

Two competing predictions regarding highly dispersible clonal plants, such as bryophytes, expect levels of genetic diversity to either increase or decrease over time following a disturbance that opens habitat for colonization. Following up on previous research that found higher levels of genetic variation in bryophytes from relatively undisturbed forest sites, we examined unisexual, haploid species of a moss (Plagiomnium ciliare), a leafy liverwort (Porella platyphylloidea), and a thalloid liverwort (Conocephalum conicum sensu lato) from the Mountains, Piedmont, and Coastal Plain of the southeastern United States. In terms of time since last disturbance, sites were ranked Mountains > Piedmont > Coastal Plain. Measures of genetic variation, including percentage of loci polymorphic, mean number of alleles per locus, mean expected heterozygosity, and number of multilocus genotypes, all fit the prediction that genetic diversity should increase over time. We also examined several components of reproductive success expected to influence levels of genetic variation, including colony size, colony mixing, sex expression, phenotypic sex ratio, and sporophyte production (percentage of females producing sporophytes). Most, but not all, of our predictions for populations of varying time since last disturbance were fulfilled, although other ecological differences related to soil, climate, and vegetation are also likely to influence reproductive success.

Response of moth communities (Lepidoptera) to forest management strategies after disturbance

Spruce forests face many threats such as climate change and bark beetle outbreaks. Yet, bark beetle dynamics have a long co-evolutionary history strongly linked to spruce forest structural dynamics. Disturbed spruce forest sites resulting from bark beetle outbreaks therefore should not be regarded as degraded land, but as early successional stages following natural forest dynamics. Three post-bark-beetle disturbance sites and one closed-canopy site in the Bavarian Forest and Ĺ umava National Parks were investigated with the focus on moth communities. The three disturbed sites had undergone different post-disturbance management regimes, with one being treated by salvage logging, while at the other two forest sites deadwood was kept in the forest. To avoid the spread of bark beetles, however, the bark of dead trees was either gouged or removed. The aim was to determine how many moths can be found at the undisturbed and disturbed forest sites and if differences in community composition can be explained by different management regimes. The results highlight that natural forest disturbance can increase moth diversity, especially by favouring species that are associated with open and shrub habitats. Many rare and endangered species benefit from bark beetle outbreaks, indicating that accepting natural forest dynamics is an important part of conservation management. Post-bark beetle management seems to have a minor effect on moth communities.

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

AbstractThe 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.

Impacts of deforestation and forest regeneration on soil bacterial communities associated with phosphorus transformation processes in the Brazilian Amazon region

Land-use change has negative impacts on the biodiversity of plants and animals. However, we lack studies and/or information about the impacts of land-use change on the biodiversity of soil microorganisms, especially those involved in the phosphorus (P) transformation processes. This represents a great concern since some microbial groups are extremely important to different P transformation processes and regulate P availability in tropical and subtropical regions. In our study, we used shotgun DNA-metagenomic sequencing and P fractionation analysis to assess the effects of forest-to-pasture conversion on the dynamics of soil bacterial groups involved in the P transformation processes and their potential functions. Additionally, we assessed if the dynamics of these specific soil bacterial groups were recovered after pasture abandonment and with secondary forest establishment. Our results demonstrated that the land-use change altered the total amount of P and its fractions in the soils. The bacterial community structure was affected by changes in soil chemical properties, mainly by changes in the aluminum, total P, and labile P contents. The bacterial groups involved in the P transformation processes and their potential functions were also affected by changes in land use. The pasture soil harbored a distinct bacterial community when compared to the primary and secondary forest sites. In general, forest-to-pasture conversion increased bacterial groups involved in the P mineralization, including Firmicutes, Cyanobacteria, and Gemmatimonadetes. Conversely, we observed an increase of Proteobacteria members (e.g., Bradyrhizobiaceae and Beijerinckiaceae) and genes related to P solubilization and mineralization after pasture abandonment and with the secondary forest re-establishment. Our multi-analytical approach suggests that forest-to-pasture conversion has negative impacts on the biodiversity of bacterial groups involved in the P transformation processes and their potential functions, while the secondary forest re-establishment can stimulate resilience. Taken together, our results indicated that the bacterial groups involved in the P transformation and their potential functions can be gradually recovered and reach intermediate and/or even similar levels to those observed in undisturbed forest sites. This brings new insights and helps to improve our knowledge about the impacts of anthropogenic actions on the soil microbiome in the Amazon region.

Influence of tree species on carbon, nitrogen, and phosphorus stocks and stoichiometry under different soil regeneration scenarios on reclaimed and afforested mine and post-fire forest sites

In this work, we present the effects of Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth), and black alder (Alnus glutinosa Gaertn.) on the carbon (Cstock), nitrogen (Nstock), and phosphorus (Pstock) stocks and stoichiometry in the uppermost soil horizons (Oi + Oe, 0–5 cm) on afforested post-mining sand-pit and post-fire forest sites. These results were compared to those for undisturbed forest sites under the same tree species. The Cstock and Nstock of the post-fire soils were similar to those of the undisturbed soils, but lower for the reclaimed mine site. Notably, tree species affected the distribution of Cstock between the organic and mineral horizons. Compared to the other tree species, pine was characterized by a higher Cstock in the Oi + Oe horizons of the post-mining and undisturbed soils. In the 0–5-cm soil horizons, the highest Cstock values were detected under alder at the post-mining site and under birch and alder at the undisturbed site. For all of the studied sites, the C:N ratios in the litter horizons occurred in the following order: alder < birch < pine. This trend was only reflected in the mineral horizons of the undisturbed sites, which indicates the very temporary impact of organic matter on the disturbed sites. The C:P and N:P ratios in the mineral soil horizons were higher for the post-fire site than the post-mining and undisturbed sites, which may indicate a P limitation for the given content of C and N. Black alder, as a N-fixer, can increase the C:P and N:P ratios in nutrient-poor, sandy soils after disturbance in comparison with the other studied tree species, especially in post-fire soils. The uppermost mineral soil horizons under alder were characterized by higher C:P and N:P ratios than the soils under pine on the post-mining site and under the other tree species on the post-fire site. The N:P ratios in the litter horizons under alder on the disturbed sites were higher than for the other tree species, while this was not true for the undisturbed soils where alder grew under nutrient-optimal conditions. This suggests that the phytomelioration influence of N-fixers on degraded and nutrient-poor soils, may be inhibited by P limitation.

Soil Organic Carbon Pools and Associated Soil Chemical Properties under Two Pine Species (Pinus sylvestris L. and Pinus nigra Arn.) Introduced on Reclaimed Sandy Soils

The roles of different tree species and their impacts are key in assessing the dynamics of soil restoration in afforested post-mining sites. The objective of this study was to compare the effect of Scots pine (Pinus sylvestris L.), which is native to Central Europe and commonly used in afforestation, to that of the non-native black pine (Pinus nigra Arn.) on the development of carbon pools and the chemical properties of reclaimed soils after sand exploitation. The study was carried out in 20- and 35-year-old stands, and the results were compared to undisturbed forest sites. Samples of the litter horizon and mineral soils (0–5 and 5–20 cm) were analyzed for pH, soil organic carbon (SOC), and total nitrogen (Nt). In addition, electrical conductivity (EC), sorption complex properties, water-soluble carbon, and hot-water-extractable carbon were determined from the mineral soil samples. Scots and black pine had a similar effect on the properties of the reclaimed soils. However, the soils under Scots pine were characterized by lower pH values in the litter and 0–5 cm horizons, higher EC in the 0–5 cm horizon, and higher C stocks in the litter horizon. Changes in the C stocks and chemical properties with afforestation years were limited to the uppermost soil horizons (litter and 0–5 cm). For both pine species, soils under the older stands were characterized by lower pH, higher EC, higher exchangeable acidity, higher cation-exchange capacity, lower base saturation, higher SOC and Nt contents, and more stable soil organic matter than soil under younger stands. After 35 years, about 20% and 27% of the C stocks in the reclaimed mine soils had been restored under black pine and Scots pine, respectively (compared to undisturbed soils). This difference between the pine species resulted from the higher C stocks in the litter horizons under Scots pine. Pedogenesis in post-mining sites after sand exploitation under pine species tended to result in more acidic and oligotrophic soils in relation to the undisturbed soils in adjacent forest ecosystems with pine.

Artisanal mining impacts small mammals while chainsaw milling is a more sustainable practice in Ghana

Logging and mining are widespread in most West African countries and considering their socio-economic importance, little is known about their ecological impacts. In this study, we investigated the effects of chainsaw milling (logging) and artisanal mining on terrestrial small mammal communities in a tropical forest in Ghana. For this, we compared abundance, diversity measures and community composition of small mammals active at the forest floor in logged, mined and undisturbed forest sites. We found that abundance was higher in logged and undisturbed forest sites than in mined sites. Small mammal species richness, Shannon diversity and Pielou’s evenness did not differ significantly among the three forest disturbance categories. Community composition of small mammals varied between mined and undisturbed sites as well as between mined and logged sites, suggesting differential species responses to altered environments. This may be due to the presence of pits in mined forest sites, hence a reduction in exploitable ground habitat structures for shelter, nesting or food. Overall, our results suggest that artisanal mining has strong impacts on community composition of forest floor small mammals in tropical forests while the effect of logging by chainsaw milling activities is minimal, especially when practiced at low intensity. This effect was moderated by elevation and distance to streams that equally shaped small mammal communities. More research on the effects of specific forms of logging and mining activities on small mammals are urgently needed to better protect species in forests impacted by logging and mining.

Sex-Segregated Range Use by Black-and-White Ruffed Lemurs (Varecia variegata) in Ranomafana National Park, Madagascar

Ranging behavior is one important strategy by which nonhuman primates obtain access to resources critical to their biological maintenance and reproductive success. As most primates live in permanent social groups, their members must balance the benefits of group living with the costs of intragroup competition for resources. However, some taxa live in more spatiotemporally flexible social groups, whose members modify patterns of association and range use as a method to mitigate these costs. Here, we describe the range use of one such taxon, the black-and-white ruffed lemur (Varecia variegata), at an undisturbed primary rain forest site in Ranomafana National Park, Madagascar, and characterize sex differences in annual home range area, overlap, and daily distances traveled. Moreover, we characterize seasonal variability in range use and ask whether ranging behaviors can be explained by either climatic or reproductive seasonality. We found that females used significantly larger home ranges than males, though sexes shared equal and moderate levels of home range overlap. Overall, range use did not vary across seasons, although within sexes, male range use varied significantly with climate. Moreover, daily path length was best predicted by day length, female reproductive state, and sex, but was unrelated to climate variables. While the patterns of range use and spatial association presented here share some similarities with “bisexually bonded” community models described for chimpanzees, we argue that ruffed lemurs best conform to a “nuclear neighborhood” community model wherein nuclear (core) groups share the highest levels of home range overlap, and where these groups cluster spatially into adjacent “neighborhoods” within the larger, communally defended territory.

Soil Physico-chemical Properties at Different Habitat Types in Disturbed and Undisturbed Sites of the Takamanda Rainforest, Cameroon

Soil fertility in tropical forest ecosystems is achieved by high and rapid circulation of nutrients, through nutrient cycling which is a function of climate variability. Decomposition is a key process in nutrient cycling and the formation of soil organic carbon. This study examines the physico-chemical properties of soils in different habitat types in the disturbed and undisturbed Takamanda rainforest. A total of 180 soil samples were collected from the different habitat types of the two forest sites. At each of the sites, soil samples were collected from the ridge tops (crest of a ridge), hilly slopes (side of a ridge), plains (low land), swamps (low land area saturated with water) and valley bottoms (trough surrounded by ridges). Soil samples were collected at 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, 40-50 cm and 50-60 cm soil depths. The results indicated that the bulk densities were highest in the habitats of hilly slope (1.43±0.35) and ridge top (1.21±0.11) in the disturbed and undisturbed forest respectively. The soil porosity was highest (73±50) in plain and valley bottoms (72±60) in the undisturbed forest. The electrical conductivity was highest (58.83±80, 57.00±4.50) in valley bottoms in both disturbed and undisturbed sites respectively. The soil textural classes noted in both top soil and subsoil in disturbed and undisturbed were loam, sandy loam, loamy sand, sandy clay loam and clay loam. The macro-nutrients (Nitrogen, Phosphorus, Organic Carbon, Sulphur, Calcium and Potassium) generally showed a decreased trend with soil depths across habitats in disturbed and undisturbed forests. The soil micronutrients (Manganese, Iron, Zinc, Copper and Nickel) showed an increased trend with soil depths across habitats in disturbed and undisturbed forest sites. Therefore, appropriate measures are necessary for conservation and management of the soils of Takamanda rainforest. This would enhance the growth and diversity of both flora and fauna of these rainforest sites.

Tree species diversity and biomass carbon assessment in undisturbed and disturbed tropical forests of Dibru-Saikhowa biosphere reserve in Assam North-East India

In the present study, the tree species phytosociological attributes, tree density, basal area, and tree biomass carbon (above- and below-ground) distribution pattern was explored in the undisturbed and disturbed forest sites in Dibru-Saikhowa biosphere reserve of Assam, northeast India. The study area is globally recognized biodiversity hotspots in India and situated in the flood plain of the Brahmaputra and Lohit River. The tree species attributes like tree density, basal area, and tree biomass carbon were estimated in three undisturbed and disturbed forest sites. Principal component analysis, redundancy analysis, and correlation analyses were conducted to explore the relationship between biodiversity indices, forest stands characteristic, and tree biomass. The undisturbed forest stand showed the highest biological attributes (29–39 species and 25–33 genera) compare to disturbed forest stands (27–32 species and 21–27 genera). Combretaceae, Lauraceae, Phyllanthaceae, Salicaceae, Myrtaceae, and Moraceae has shown a higher importance value index. The biodiversity indices were significantly higher in undisturbed forest stands and the Shannon–Wiener diversity index (H′) ranged from 1.97 to 3.57, Simpson index (Cd) ranged from 0.76 to 0.88, and evenness index (e) ranged from 0.65 to 0.97 in all the stands. The mean tree density and forest basal area were significantly higher in the undisturbed forest (796.66 ha−1 and 56.56 m2 ha−1, respectively) compared to disturbed forest stands (436.66 ha−1 and 38.91 m2 ha−1, respectively). Tree biomass carbon in undisturbed forest (184–214.62 Mg C ha−1) was also more than disturbed forests (124–137.53 Mg C ha−1). Moreover, the biomass carbon was greatly affected by the tree composition, diversity, density, and the disturbances in forest stands. The present study will provide the baseline information for effective and sustainable tree species diversity conservation and evaluate tree carbon stock in the Dibru-Saikhowa biosphere reserve.

Arbuscular mycorrhizal fungi in Melocanna baccifera from disturbed and undisturbed sites in Mizoram, India

Melocanna baccifera is a well-known native bamboo species of India belonging to the grass family Poaceae. A study on the presence of arbuscular mycorrhizal fungi (AMF) association with M. baccifera was conducted from a disturbed and undisturbed bamboo forest sites within Mizoram University, Mizoram, India. Soil from the rhizosphere region as well as physico-chemical properties of the soil were taken to study AMF diversity. The roots were observed for percentage colonization by AMF. It was found that undisturbed site had higher colonization percentage (56%) than the disturbed site (46%). The Shannon’s diversity index showed that undisturbed site (1.46) had more diversity than the disturbed site (1.59) while disturbed site showed lower index of dominance (3.34) which indicates higher shared dominance of AMF species than undisturbed site (4.66).

Canonical Correlation Analysis across Vegetation and Soil Properties of the Disturbed and Undisturbed Coastal Forest Ecosystems

This study presents comparative initial information about canonical correlation across forest stand parameters, diversity indices and soil properties in undisturbed forest sites (IFS), agriculture disturbed sites (ADS) and livestock disturbed sites (DGS). Data were collected from Uzigua Forest Reserve in Tanzania. Forty- seven sample plots of 25 m × 25 m were randomly established on IFS, ADS and DGS from which tree inventory data and 141 soil samples were drawn. Data were subjected into Canoco windows 4.5 software for multivariate analyses and comparisons across IFS, ADS and DGS. The correlation of tree stand parameters (TSP) and soil physical properties (SPP) were F=1.207, p=0.242 in IFS, F=2.400, p=0.012 in ADS and F=0.529, p=0.938 in DGS. For soluble bases and TSP were F=2.448, p=0.018 in IFS, F=0.687, p=0.790 in ADS and F=0.743, p=0.808 in DGS. Carbon, nitrogen and potassium (CNP) and TSP were F=0.816, p=0.572 in IFS, F=0.687, p=0.790 in ADS and F=0.070, p=0.020 in DGS. The SPP and Shannon indices had F=1.103, p&lt;0.388 in IFS, F=0.520, p=0.714 in ADS and F=0.932, p=0.444 in DGS. The SPP and Independent Value Index (IVI) were F=0.042, p=0.996 in IFS, F=0.819, p=0.620 in ADS and F=0.633, p=0.724 in DGS. Soluble bases and equitability were F=0.119, p=0.968 in IFS, F=0.001, p=0.001 in ADS and F=0.011, p=0.001 in DGS. The CNP and IVI had F=4.246, p=0.014 in IFS, F=2.729, p=0.018 in ADS and F=2.007, p=0.060 in DGS. The mean higher canonical correlation in the non-disturbed sites indicates that crop-agriculture and livestock grazing affect the interplays between forest vegetation and soil properties. Therefore, human activity disturbs the structure and soil properties.

Conservation value of moist evergreen Afromontane forest sites with different management and history in southwestern Ethiopia

Tropical forest ecosystems harbor high biodiversity, but they have suffered from ongoing human-induced degradation. We investigated the conservation value of moist evergreen Afromontane forest sites across gradients of site-level disturbance, landscape context and forest history in southwestern Ethiopia. We surveyed woody plants at 108 randomly selected sites and grouped them into forest specialist, pioneer, and generalist species. First, we investigated if coffee dominance, current distance from the forest edge, forest history, heat load and altitude structured the variation in species composition using constrained correspondence analysis. Second, we modelled species richness in response to the same explanatory variables. Our findings show that woody plant community composition was significantly structured by altitude, forest history, coffee dominance and current distance from forest edge. Specifically, (1) total species richness and forest specialist species richness were affected by coffee management intensity; (2) forest specialist species richness increased, while pioneer species decreased with increasing distance from the forest edge; and (3) forest specialist species richness was lower in secondary forest compared to in primary forest. These findings show that coffee management intensity, landscape context and forest history in combination influence local and landscape level biodiversity. We suggest conservation strategies that foster the maintenance of large undisturbed forest sites and that prioritize local species in managed and regenerating forests. Creation of a biosphere reserve and shade coffee certification could be useful to benefit both effective conservation and people's livelihoods.

Energy and CO2 exchange in an undisturbed spruce forest and clear-cut in the Southern Taiga

Effects of clear cutting and other forest disturbances on surface radiative properties and the energy and CO2 fluxes between land surface and the atmosphere can vary significantly depending on local climatic and moisture conditions, forest structure and species composition, soil properties and many other factors. In this study we analyzed the influence of clear-cutting on the energy, water vapor and CO2 fluxes in the still very poorly investigated part of the boreal forest community in the European part of Russia. This issue has become particularly relevant due to intensified logging in the region during recent decades. The sensible (H) and latent (LE) heat, as well as CO2 fluxes were continuously measured at recently clear-cut and undisturbed mature spruce forest sites using eddy covariance technique during the first growing season following harvest. Because of their close location they are characterized by similar meteorological conditions. The results of our field measurements showed that the clear-cut strongly influenced the energy balance and CO2 fluxes between the land surface and atmosphere. Energy fluxes (LE and H) at the undisturbed forest site were consistently larger than at the clear-cut throughout the period of measurements. The Bowen ratio (β=H/LE) varied significantly over time, though was similar at both sites. Whereas H was almost equal to LE at both sites in spring, the LE significantly exceeded H over the summer (β≈0.2 - for mature spruce forest and β = 0.4 - for clear-cut). The mean β for the entire period was similar (β≈0.5) at both sites. Analysis of CO2 fluxes showed that the clear-cut was a consistent source of CO2 to the atmosphere. Net ecosystem exchange (NEE) at the clear-cut averaged 3.3 ± 1.3 gC∙m−2∙d-1 (±1 SD), while average NEE at the undisturbed mature forest was close to zero (0.1 ± 1.9 gC∙m−2∙d-1). Differences in NEE were mainly governed by differences in gross primary productivity (GPP) between sites (7.0 ± 4.1 gC∙m−2∙d-1 and 4.1 ± 3.0 gC∙m−2∙d-1, for the undisturbed forest and clear-cut, respectively). Total ecosystem respiration (TER) did not significantly (p < 0.05) differ between sites (7.1 ± 3.6 gC∙m−2∙d-1 at the undisturbed mature forest and 7.4 ± 3.4 gC∙m−2∙d-1 at clear-cut). TER at the undisturbed forest showed higher sensitivity to changes in soil temperature, whereas GPP at the clear-cut was characterized by higher light-use efficiency. Our measurements showed that TER rates were relatively high in the southern taiga in comparison with other boreal sites where CO2 fluxes were previously investigated.

Anthropogenic disturbances shift diameter distribution of woody plant species in Shorea robusta Gaertn. (Sal) mixed forests of Nepal

Assessing diameter distribution is an approach of observing regeneration strategies and impacts of anthropogenic disturbances on forest structural attributes. In this study, we evaluated the differences in diameter distributions in highly disturbed, moderately disturbed, and undisturbed forest sites of Buffer Zone Community Forests (BZCFs), viz. Janajagaran BZCF, Musharni Mai BZCF, and Radha Krishna BZCF of Central Terai, Nepal. Weibull and gamma distributions were fitted to explain changes in frequency distribution of diameter data collected. We observed a significant decrease in species richness (overall: p < 0.001) and density of smallest diameter class (0–10 cm diameter at breast height) stems (overall: p < 0.001) with increasing disturbances. Similarly, increase in median diameters (p < 0.01) and parameters of Weibull’s and gamma distributions along gradients from undisturbed to highly disturbed forest sites (except between moderately disturbed and undisturbed sites of Musharni Mai BZCF) were observed. Bowley coefficient of skewness was lower in all highly disturbed sites of BZCFs showing reduction in right skewness of the distribution curves with disturbances. These results indicate anthropogenic disturbances shift diameter structure of forests stands, negatively affecting abundance of small diameter–sized woody species and shifting Shorea robusta mixed forests towards even-aged stands.

Development of Technosol properties and recovery of carbon stock after 16 years of revegetation on coal mine degraded lands, India

Surface mining is recognized as one of the essential anthropogenic activities which drastically disturbs the ecosystem. To offset the impacts of surface mining, revegetation is widely used to restore the disturbed landscape. The present field study was carried out to assess the status of an ecosystem structure, soil quality and C pool of the 16-years old revegetated post-mining site and compared to an undisturbed forest site. For this, physicochemical, biological and hydrological properties of Technosols were analyzed, and differences in these parameters were quantified. Vertical distribution of soil nutrients (NPK), soil organic carbon (SOC) and soil inorganic carbon (SIC) were assessed in the upper 100 cm (at an interval of 20 cm) of Technosols and forest soils. After 16-years of revegetation, autochthonous tree species comprise 17% of the total tree population on the reclaimed site. Technosol quality was increased in terms of accumulation of SOC, available nitrogen (N), and available phosphorus (P). SOC and total N stock recovered in Technosols were 70% and 47% of the reference forest soils, respectively. Likewise, after 16-years of revegetation, ecosystem C pool was 33% of the undisturbed forest site. Increase in C pool can be attributed to the development of plant biomass C, accretion of SOC and litter C pool. The study provides an insight into the magnitude of nutrient content and development of ecosystem C pool in a reconstructed ecosystem and importance of revegetation of post-mining sites to offset CO2 emission. The study concluded that plantation of multipurpose tree (MPT) species will improves Technosol quality, facilitates natural colonization of native tree species and increases ecosystem C pool along the age of revegetation.

Changes from pasture to a native tree plantation affect soil organic matter in a tropical soil, Panamá

We examined changes in soil organic matter arising from conversion of a 45-year old pasture to a 10 yr. old native tree plantation in Panama, to evaluate the effect of monoculture and mixtures. We intensively sampled the soil 0–10 cm depth in the pasture in 2001 and in 22 plantation plots in 2011, ranging from 5 monocultures to 3- and 6-species treatments; samples were also taken from an undisturbed forest site. Soil analyses included organic carbon (SOC) and δ13C. Conversion of the pasture to tree plantation resulted in an overall loss of SOC of 0.6 kg m−2 (18%) in the top 10 cm, but neither tree species nor diversity had a significant effect. End-member δ13C values suggested that the contribution of C3 plants to SOC was increased from 26% in the pasture to 55% after 10 years of plantation and SOC turnover times were calculated to be 21–36 yr. The magnitude of the loss in soil SOC is smaller than the increases in tree biomass (~3 kg C m−2) and litter (~0.3 kg C m−2) in the plantation, but still a significant part of the ecosystem C balance.

Effects of Habitat Disturbance on Lizard Functional Diversity in a Tropical Dry Forest of the Pacific Coast of Mexico

Tropical dry forests are complex and diverse ecosystems threatened by multiple anthropogenic factors, such as habitat disturbance caused by land use change. We assessed species and functional diversity of lizard communities in areas with different levels of tropical dry forest disturbance in the Chamela region, Mexico. Functional richness, functional evenness, and functional dispersion were assessed considering six lizard functional traits. We recorded 415 lizards of 15 species. Species richness, species diversity, functional richness, functional dispersion, and the number of functional groups are lower in disturbed sites than in undisturbed tropical dry forest sites. On the contrary, abundance and functional evenness were higher in strongly disturbed sites. We suggest that lizard functional diversity should be studied further in order to secure the integrity of herpetofaunal communities and ecosystem processes.