Litter Inputs Research Articles

Influence of vegetation cover on the functional diversity of macroinvertebrates associated with leaf litter in a stream of the tropical dry forest

Vegetation is a fundamental element for the maintenance of macroinvertebrates functional diversity and, therefore, essential to aquatic trophic net preservation, being particularly relevant in threatened ecosystems such as tropical dry forests. Our aim is to determine the relationship between vegetal cover conservation and macroinvertebrates functional diversity associated with litter, in a stream from a tropical dry forest. In La Avería stream (Huila, Colombia), we sampled sites with different vegetation cover, estimated their physicochemical variables, and calculated leaf litter inputs (vertical, side, and drift) for each station for a whole year. Subsequently, we recorded the macroinvertebrates associated with litter from common vegetal species using leaf traps. We performed a PERMANOVA, added to multiple linear regression models and a redundancy analysis to correlate our environmental variables with changes in functional diversity. We observed changes in the functional parameters related to sampling zones and time. On one hand, functional richness and distance, are associated with dry seasons when resource availability and environmental conditions are stabilized. On the other hand, the functional evenness value diminishes in areas with higher pH due to the loss of individuals. We found evidence of a relationship between physicochemical variables and functional diversity. pH and precipitation changes were directly associated with changes in litter supply and therefore define the dimensionality of the functional traits in the ecosystem. Our work emphasizes the idea that the macroinvertebrate diversity carries great potential as a tool for decision-making in the preservation and environmental management of aquatic and riparian systems.

Implications of alder shrub growth for alpine tundra soil properties in Interior Alaska

ABSTRACT The increase in deciduous shrub growth in response to climate change throughout the Arctic tundra has uncertain implications, in part due to a lack of field observations. Here we investigate how increasing alder shrub growth in alpine tundra in Interior Alaska corresponds to active layer thickness and soil physical properties. We documented increased alder growth by combining biomass harvests and dendrochronology with the analysis of remotely sensed Normalized Difference Vegetation Index and fire history. Active layer thickness was measured with a tile probe and carbon and nitrogen pools were assessed via elemental analysis. Shallower organic layers under increasing alder growth indicate that nitrogen-rich, deciduous litter inputs may play a role in accelerating decomposition. Despite the observed reduction in organic carbon stocks, active layer thickness was the same under alder and adjacent graminoid tundra, implying deeper thaw of the underlying mineral soil. This study provides further evidence that the widely observed expansion of deciduous shrubs into graminoid tundra will reduce ecosystem carbon stocks and intensify soil–atmosphere thermal coupling.

Decomposability of leaf and wood litter are not correlated across species: effects of litter traits on decomposition in field and laboratory conditions

Changes in tree species composition have important effects on the overall rate of litter decomposition at a community level because litter decomposability varies among species and between leaf and wood litter. To understand how changes in tree species composition affect litter dynamics and carbon sequestration at the ecosystem level, it is important to clarify interspecific variations in leaf and wood litter decomposability, and the traits driving the variation. Using field data, field experiments, and laboratory experiments, we explored rates of leaf and wood litter decomposition and their relationships to traits of ten deciduous hardwood species in a temperate forest in Japan. Rates of leaf and wood litter decomposition at the community level were also estimated by considering species‐specific litter inputs and decomposition rates. Rates of leaf and wood litter decomposition were not correlated under either field or controlled laboratory conditions. This is probably because the traits that affect decomposition rate differ between leaf and wood litter. Interspecific variation in litter decomposability of leaves and wood was generally consistent between field conditions and laboratory experiments using a single fungus, suggesting that the decomposing fungi set the species‐specific decomposition rates. Moreover, the leaf and wood traits that affected decomposition by their specific fungi were different. The aboveground input of wood litter was less than half that of leaf litter, but its half‐life was > 3 times longer, suggesting that wood and leaves make similar contributions to litter accumulation. Focusing on either leaf or wood litter alone may produce misleading estimates of how species composition changes affect litter dynamics at the community level. Our results provide insight into predicting the response of carbon dynamics to future climate change.

Peatland restoration pathways to mitigate greenhouse gas emissions and retain peat carbon

Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere.

Effects of litter and root inputs on soil CH4 uptake rates and associated microbial abundances in natural temperature subalpine forests

Climate change altered the quantities of aboveground plant litter and root inputs, but the effects on soil CH4 uptake rates and underlying mechanisms remain unclear. To investigate these factors, a three-year detritus input and removal treatment (DIRT) study including six treatments (namely, CK, control; NL, litter removal; DL, double litter; NR, root exclusion; NRNL, root exclusion plus litter removal; and NRDL, root exclusion plus double litter) was conducted in broadleaf and coniferous forest subalpine forest ecosystems. The results showed that both the subalpine forest soils acted as sink for atmospheric CH4 across all treatments, while the broadleaf forest had consistently higher CH4 uptake rates than the coniferous forest. Based on the annual mean values, root exclusion (NR, NRNL and NRDL) significantly decreased soil CH4 uptake rates by 35.9 %, 31.0 % and 43.4 % in the broadleaf forest and 36.7 %, 31.9 % and 40.6 % in the coniferous forest compared with CK treatments, respectively. Meanwhile, the mean soil CH4 uptake rates were significantly reduced by 23.6 % and 17.3 % in the broadleaf forest and the coniferous forest under the DL treatments, respectively; nevertheless, the NL treatment significantly increased soil CH4 uptake rates by 19.68 % and 14.4 %, respectively. The results clearly demonstrated that root exclusion exerted a greater influence on soil CH4 uptake rates than plant litter manipulations. Correlation and redundancy analysis (RDA) revealed that the separation of root exclusion treatments from aboveground plant litter manipulations was based on higher soil water content, NH4+-N and NO3−-N concentrations, and lower DOC (dissolved organic carbon) concentrations and methanotroph pmoA gene abundance. The results suggest that future alterations in aboveground plant litter and root input, particularly a reduction in root input, can exert a stronger influence on regulating soil CH4 uptake than aboveground litter manipulations in subalpine forests with cold and humid climatic conditions in response to future climate scenarios.

Hurricane disturbance drives trophic changes in neotropical mountain stream food webs.

Food webs are complex ecological networks that reveal species interactions and energy flow in ecosystems. Prevailing ecological knowledge on forested streams suggests that their food webs are based on allochthonous carbon, driven by a constant supply of organic matter from adjacent vegetation and limited primary production due to low light conditions. Extreme climatic disturbances can disrupt these natural ecosystem dynamics by altering resource availability, which leads to changes in food web structure and functioning. Here, we quantify the response of stream food webs to two major hurricanes (Irma and María, Category 5 and 4, respectively) that struck Puerto Rico in September 2017. Within two tropical forested streams (first and second order), we collected ecosystem and food web data 6 months prior to the hurricanes and 2, 9, and 18 months afterward. We assessed the structural (e.g., canopy) and hydrological (e.g., discharge) characteristics of the ecosystem and monitored changes in basal resources (i.e., algae, biofilm, and leaf litter), consumers (e.g., aquatic invertebrates, riparian consumers), and applied Layman's community-wide metrics using the isotopic composition of 13 C and 15 N. Continuous stream discharge measurements indicated that the hurricanes did not cause an extreme hydrological event. However, the sixfold increase in canopy openness and associated changes in litter input appeared to trigger an increase in primary production. These food webs were primarily based on terrestrially derived carbon before the hurricanes, but most taxa (including Atya and Xiphocaris shrimp, the consumers with highest biomass) shifted their food source to autochthonous carbon within 2 months of the hurricanes. We also found evidence that the hurricanes dramatically altered the structure of the food web, resulting in shorter (i.e., smaller food-chain length), narrower (i.e., lower diversity of carbon sources) food webs, as well as increased trophic species packing. This study demonstrates how hurricane disturbance can alter stream food webs, changing the trophic base from allochthonous to autochthonous resources via changes in the physical environment (i.e., canopy defoliation). As hurricanes become more frequent and severe due to climate change, our findings greatly contribute to our understanding of the mechanisms that maintain forested stream trophic interactions amidst global change.

Illegal dumping from ships is responsible for most drink bottle litter even far from shipping lanes

Recent studies using bottles as tracers have shown that illegal dumping from ships is responsible for the rapid increase in drink bottles washing up on oceanic islands and at remote continental beaches away from local litter inputs. However, these studies have been in areas with moderate to high levels of shipping activity. I examined bottles stranded on the Pitcairn Islands in the central South Pacific, which are far from major shipping routes. Drink bottles from Asia dominated, with most coming from China. The top four brands (three Chinese and one multinational) were the same as at Tristan da Cunha in the central South Atlantic Ocean, which lies on the shipping route between South America and Asia. Bottle ages also were similar at Pitcairn and Tristan, indicating that vessels are the main source of bottles at both islands. Stricter controls are needed to reduce illegal dumping of plastics at sea.

Among the trees: shade promotes the growth and higher survival of juvenile toads

getation, including trees, significantly shapes microhabitats for amphibians due to the leaf litter input, providing stable shelter, creating a microclimate or indirectly through trophic interactions. It is known that some species can survive in a highly modified urban environment. Species associated with open space can find stable habitats in urban and human-transformed areas, but is the impact of shading (presence of canopy cover) significant in their case? We focus on the effect of solar exposure on the growth rate of juvenile green toads Bufotes viridis in fruit and canopy manipulation treatments. The main aim of the study was to examine the selected habitat traits promoting post-metamorphic growth of the green toad in semi-open enclosures. We investigated differences between exposure/land cover variants, i.e., sunny site (open area with direct solar exposure) and shadow site (shady site with a tree canopy cover). Using imitation fruits and real cherry plum Prunus cerasifera fruits (non-native tree species), we checked wheth­er amphibian growth is related to the additional structure that fruit lying on the ground created (a more heterogeneous surface structure) or to a trophic character (additional food source due to attracting inver­tebrates). We conducted a 40-day rearing experiment in three variants with two replications in semi-open enclosures with 20 juvenile toads each. We found differences in snout-vent length and body mass index in­vestigated due to site exposure during post-metamorphic growth. The survival rate of juvenile toads in the shaded site was higher than in sunny sites. We demonstrated a positive effect of the tree’s shade, regardless of the fleshy fruit’s presence on the ground. Toads benefit from developing at sites with reduced solar ex­posure (i.e., with a tree canopy), resulting in intensive growth and higher survival rate. Thus, there is an opportunity for planners and urban authorities to manage habitats for amphibian conservation purposes by creating a shaded zone, even for open habitat species, especially in transformed areas such as cities. Our results indicate that the beneficial effect of the lying fruit on the growth of juveniles is limited to specific conditions, and understanding this requires further research.

Corn straw biochar addition elevated phosphorus availability in a coastal salt-affected soil under the conditions of different halophyte litter input and moisture contents

Improving salt-affected soil health using different strategies is of great significance for Sustainable Development Goals. The effects of biochar as a sustainable carbon negative soil amendment on phosphorous (P) pools in the degraded salt-affected soils of the of coastal wetlands (as one of the primary blue carbon ecosystems) with halophyte litter input under different water conditions (the two intrinsic characteristics of coastal wetlands) are poorly understood. Thus, a corn straw derived biochar (CBC) was added into a coastal salt-affected soil collected from the Yellow River Delta to investigate its effect on P fractions and availability under the input of three different local halophyte litters (i.e., Suaeda salsa, Imperata cylindrica and Phragmites australis) and under the unflooded and flooded water conditions. The results showed that the individual input of Suaeda salsa increased soil P availability by 28.2–40.9 %, but Imperata cylindrica and Phragmites australis had little effect on P availability. CBC individual amendment more efficiently enhanced P availability in the unflooded soil than the flooded soil. However, the co-amendment of CBC with litters showed little synergistic effect on P availability. CBC sharply increased the proportion of Ca-bound labile P fraction, but moderately lifted the proportion of Al/Fe-bound mediumly labile P fraction. CBC-enhanced P availability and altered inorganic P fractions were mainly resulted from the provision of labile inherent P by biochar, improved soil properties (i.e., increased CEC), and altered bacterial community composition (i.e., elevated abundance of P-solubilizing and phosphate-accumulating bacteria). These findings give new insights into understanding P biogeochemical cycling in the coastal salt-affected soils amended with biochars, and will be helpful to develop biochar-based technologies for enhancing P pools and improving soil health of the blue carbon ecosystems.

Impacts of aboveground litter and belowground roots on soil greenhouse gas emissions: Evidence from a DIRT experiment in a pine plantation

Plant detritus alteration may influence soil greenhouse gas emissions, but the direction, extent and mechanisms remain uncertain. Here we conducted a DIRT (Detritus Input and Removal Treatment) experiment in a Pinus sylvestris var. mongolica plantation in Saihanba (Hebei Province, China), manipulating aboveground litter (L-: litter removal, L: normal litter, L+: litter doubling) and belowground roots (R-: root removal, R: with root) resulting in six treatments. We measured CO2, N2O, and CH4 fluxes during 2019 and 2020 growing seasons, along with soil physicochemical, enzymatic and microbial variables. Our findings revealed that soil CO2 and N2O emissions increased with litter input, while CH4 uptake decreased. The absence of roots decreased soil CO2 emission and CH4 uptake but increased N2O emission. Aboveground litter enhanced the carbon cycling variables, such as extractable organic carbon (EOC), the ratio of soil extractable organic carbon to extractable total nitrogen (EOC:ETN), soil carbon mineralization rate (Cmin), and peroxidase activity (PER), resulting in increased CO2 emission. In contrast, the absence of roots increased the nitrogen cycling variables, such as soil extractable total nitrogen (ETN), nitrate nitrogen content (NO3−-N), the ratio of soil extractable organic carbon to extractable total nitrogen (EOC:ETN), soil net nitrogen mineralization rate (Nmin), and the abundance of ammonia-oxidizing bacteria (AOB), leading to increased N2O emission. Moreover, soil CH4 uptake was mainly influenced by soil microclimate: aboveground litter input reduced CH4 uptake by lowering soil temperature, while belowground roots benefited CH4 uptake via reducing soil moisture by water uptake. Taken together, our study suggests that soil CO2, N2O, and CH4 emissions (or uptake) are influenced by both aboveground and belowground plant inputs through various pathways. While aboveground litter input promotes the emissions of greenhouse gasses, the mitigating effect of belowground roots on N2O and CH4 partially offsets the increment of CO2 emission in this plantation.

Impacts of land use history on leaf litter input, chemical composition, decomposition and related nutrient cycling in young and old secondary tropical lowland rainforests (Sumatra, Indonesia)

BackgroundNutrient cycle in tropical forests is mainly driven by litter fall amounts and by litter decay due to litter physical and chemical properties. Apart from differences in site conditions, different successional stages of tropical rainforests may influence nutrient inputs to the soil via differences in litter fall and decay.MethodsWe studied leaf litter fall, decomposition and related nutrient input to the soil in two secondary tropical rainforest types differing in land-use intensity and history in the lowlands of Sumatra (Indonesia).ResultsMean annual litter fall was by 29.5% higher in the old than in the young secondary forests. In contrast, annual litter decomposition differed only marginally (54.9% vs. 52.1%) in young vs. old secondary forests. Litter chemical composition (C, N, P, K contents) did not differ between the forest types. Litter decomposition was also not different between the forest types (4.6% vs. 4.3% loss of initial weight per month). Consequently, annual nutrient input to the soil was primarily affected by differences in leaf litter production, thus, old secondary forests exceeded that of young secondary forests by 30% and 24% for C and N, but was not different regaring P and K among the two forest types.ConclusionsThe results indicate that litter nutrient inputs to the soil in the two types of secondary tropical lowland forests are most strongly influenced by aboveground litter production rather than litter chemical quality or litter decay. We conclude that the restoration status of secondary tropical lowland forests is crucial for the nutrient status of these forest ecosystems.

Herbivores influence biogeochemical processes by altering litter quality and quantity in a subarctic wetland

Global change drivers that modify the quality and quantity of litter inputs to soil affect greenhouse gas fluxes, and thereby constitute a feedback to climate change. Carbon cycling in the Yukon–Kuskokwim (Y–K) River Delta, a subarctic wetland system, is influenced by landscape variations in litter quality and quantity generated by herbivores (migratory birds) that create ‘grazing lawns’ of short stature, nitrogen-rich vegetation. To identify the mechanisms by which these changes in litter inputs affect soil carbon balance, we independently manipulated qualities and quantities of litter representative of levels found in the Y–K Delta in a fully factorial microcosm experiment. We measured CO2 fluxes from these microcosms weekly. To help us identify how litter inputs influenced greenhouse gas fluxes, we sequenced soil fungal and bacterial communities, and measured soil microbial biomass carbon, dissolved carbon, inorganic nitrogen, and enzyme activity. We found that positive correlations between litter input quantity and CO2 flux were dependent upon litter type, due to differences in litter stoichiometry and changes to the structure of decomposer communities, especially the soil fungi. These community shifts were particularly pronounced when litter was added in the form of herbivore feces, and in litter input treatments that induced nitrogen limitation (i.e., senesced litter). The sensitivity of carbon cycling to litter quality and quantity in this system demonstrates that herbivores can strongly impact greenhouse gas fluxes through their influence on plant growth and tissue chemistry.Graphical abstract

Revegetation type affected soil C, N, P stocks and stoichiometry in a reclaimed mine area in Shanxi province, China

Soil stoichiometry serves as an indicator for balance of soil C, N, P pools and for the maintenance of ecosystem stability and function. Especially in seriously degraded lands, it can also reflect the status of soil recovery. However, the response of soil elements and stoichiometry to patterns of plant restoration remains unclear. In this study, soil organic C, N, P stocks and stoichiometry along a succession gradient of vegetation types were investigated in a reclaimed post-mining area in Shanxi province. Soil C and N stocks varied significantly with revegetation types while soil P stock showed no significant difference. Revegetation type significantly influenced soil C, N stocks and stoichiometry by affecting litter and fine root inputs, and consequently modifying the rates of C sequestration and nutrient release. The maximum of C and N stocks occurred in a naturally-restored shrub land with largest fine root biomass, resulting mainly from its diverse species including some legumes. Although soil C and N stocks increased significantly with succession gradient after twenty years of restoration, they were still lower than those of a nearby undisturbed site. Furthermore, soil C:N and C:P values varied among revegetation types, and the mean soil C:P (11.63) and N:P (1.03) values were significantly lower than the average level across China, indicating serious soil C and N shortage. Our result implied that shrubs with diverse species might be the most efficient plant type to rebuild soil C and N stocks, and consequently would promote restoration process of degraded lands.

Do earthworm and litter inputs promote decomposition or stabilization of cryoturnated organic matter from melted permafrost?

As global climate change progresses, Artic permafrost melts. Deeper layers of permafrost contain organic matter which can migrate into deeper soil by a process called cryoturbation. While this organic matter does not decompose in frozen soils, it decomposes rapidly in melting permafrost. Warming soils may experience increased litter input and earthworm colonization. The effects of litter addition and earthworm colonization on the decomposition and condition of permafrost remain unclear. This study used laboratory experiments to compare effects of willow litter (Salix caprea) addition and earthworm activity (Aporectodea caliginosa) on cryogenic organic matterfrom permafrost soils mixed in mineral soil and mineral soil itself. Respiration and stability of organic matter was monitored over two years with new litter added three times once litter in the soil with earthworms had disappeared from the soil surface. After a two-year period, treatments with litter addition and with earthworms alone showed increased system respiration, but effects were non-cumulative. The soil samples receiving earthworms showed higher proportions of organic matter stabilized in the mineral fraction by the end of the experiment. These preliminary lab results suggest that litter supply and earthworm colonization may both stabilize and speed up mineralization of organic matter released from melting permafrost.

Weak responses of soil microorganisms to leaf litter inputs after native Phyllostachys edulis invasion into adjacent native forests

Weak responses of soil microorganisms to leaf litter inputs after native Phyllostachys edulis invasion into adjacent native forests

Long-term effects on water chemistry and macroinvertebrates of selective thinning along small boreal forest streams

The maintenance of narrow strips of trees (forest buffers) along the shorelines of surface water bodies during logging is a common measure to protect freshwater habitats. The functionality of forest buffers may be improved by actively managing the streamside forest early in the rotation for their eventual function as buffers, including by increasing the proportion of broadleaf trees in spruce-dominated stands. In this study, long-term effects of different selective thinning regimes along two small forest streams were investigated in south-central Sweden. In a young coniferous forest, a c. 10 m-wide band along the streams was selectively thinned in 1998 to create a band with purely broadleaf trees along one of the streams and purely conifers along the other. Forest stand characteristics, water chemistry and benthic macroinvertebrates data were collected during 1996–2003 (before and after selective thinning). The streams were re-investigated 20–22 years after thinning, together with three streams representing operational forest management. The forest adjacent to all five streams was inventoried and litterfall, stream water chemistry, and benthic macroinvertebrates composition were monitored between spring and late autumn during 2018–2020. Twenty years after thinning, the thinned bands beside the streams were still dominated by either broadleaf trees or conifers, depending on the stream. Over the longer term, the differences in water chemistry between the streams with selective thinning were mainly related to lower pH, ANC, Tot-P and Tot-N concentrations in the stream bordered by mainly broadleaf trees. Analysis of benthic macroinvertebrates was based on environmental quality indices (ASPT and EPT), diversity and abundance metrics, and relative abundances of functional feeding groups. Streams with higher broadleaf litter inputs tended to score better on the ASPT and EPT indices than those with lower broadleaf inputs, as well as supporting higher relative abundances of one or more groups of invertebrate detritivores (leaf shredders, collector-gatherers and/or passive filter feeders). This suggests that management of the density of broadleaf trees beside these streams might support higher ecological status and will support a greater proportion of detritivores in benthic food webs.

Fine‐root turnover and leaf litterfall of Salsola passerina facilitate soil restoration in Alxa steppe desert of northwest China

Nutrient cycling in desert ecosystems is heavily reliant on the fine root turnover and litter decomposition processes of dominant plant species. Based on field investigations and laboratory experiments, we explored fine root production (FRP) and turnover of Salsola passerina in Alxa steppe desert, and assessed fine root and leaf litter input and its correlation with soil C and N stocks, and then compared the variability of soil physicochemical properties at the site below and the interspace of S. passerina canopy. Results showed that fine root biomass dynamics of S. passerina were consistent with soil water content. Annual FRP of S. passerina was 243.3 g m−2 yr−1 and the turnover rate was 2.0 per year. S. passerina contributed 172.2 g C m−2 and 6.8 g N m−2 to soil from its fine root senescence and leaf litter input annually. Compared to the canopy interspace, the soil texture and fertility beneath the shrubs significantly improved, while the soil salinity decreased. The results indicated that the activities of desert shrub growth provided the degraded soil with abundant nutrients through fine root turnover and litter decomposition processes, which promoted soil texture and nutrition heterogeneity at the stand scale, and played an important role in degraded dryland restoration.

Litter and soil properties under woody and non-woody vegetation types: Implication for ecosystem management in a mountainous semi-arid landscape

There are contrasting reports about whether and how vegetation types influence litter and soil properties. Accurate and comprehensive assessment of the complex relationship between vegetation types, litter and soil characteristics in semi-arid mountain landscapes is almost unknown. Thus, the purpose of this research was to study the effects of (1) Carpinus orientalis Miller., (2) Crataegus melanocarpa M.B., (3) Rhamnus pallasii Fisch. and C.A.Mey, (4) Agropyron longiaristatum Boiss, (5) Bromus tomentolus Bioss. and (6) Hordeum vulgare L. on litter properties and soil physical, chemical, biochemical and biological features in northern Iran. A sampling of the organic layer (litter) and mineral soil (30 × 30 cm) from a depth of 0–10 cm was done for all characteristics in the summer season and for soil microclimate and biological characteristics in the summer and fall seasons. A total of 90 litter samples, 90 soil samples in summer and 90 soil samples in fall (6 vegetation types × 2 seasons × 15 samples) were taken from the area and transferred to the laboratory. Results showed that the Carpinus improved litter properties, soil organic matter contents, total N and available nutrients (P, K, Ca and Mg) and enzyme activities (urease, acid phosphatase, arylsulfatase and invertase). In addition, the population of earthworm groups (epigeic, anecic, and endogeic), acarina, collembola, nematodes, protozoa (especially in the fall season) and bacteria and fungi (especially in the summer season) under Carpinus significantly increased. Data analysis demonstrated higher soil fertility and biological activities in the woody vegetation, which can be assigned to the higher litter input and nutrients. Overall, the findings of this study showed that woody vegetation, especially Carpinus, can improve soil properties at high altitudes of mountainous, semi-arid sites that are often considered as especially fragile and sensitive ecosystems.

Altering Natural Ecosystems Causes Negative Consequences on the Soil Physical Qualities: An Evidence-Based Study from Nilgiri Hill Region of Western Ghats, India

Land use change (LUC) has direct and indirect consequences on soil quality. To gain insight into how LUC influences the physical properties of soil, it can be advantageous to compare undisturbed ecosystems with those that have naturally evolved over time, as well as to use soil quality indices to pinpoint the sensitivity of each ecosystem and land use change (LUC). A soil survey was carried out in the six major ecosystems of the Nilgiri Hill Region: cropland (CL), deciduous forest (DF), evergreen forest (EF), forest plantation (FP), scrubland (SL), and tea plantation (TP), with those having an establishment for over 50 years being selected and analyzed for soil physical parameters. In addition, soil quality indices were also derived to pinpoint the vulnerability of each ecosystem to LUC. The results reveal that the changes in land use significantly altered the soil physical properties. The content of clay was higher in EF and DF and increased with the soil profile’s depth, whereas the sand content was higher in CL and TP and decreased with the depth increment. BD and PD were significantly lower in EF, DF, SL, and FP, whereas they were higher in CL and TP. PS and ASM followed a similar trend to BD and PD. Owing to undisturbed natural settings, an abundance of litter input, and higher carbon concentrations, the HC was higher in EF, DF, SL, and FP, whereas, in the case of anthropogenic-influenced ecosystems such as CL and TP, it was lower. We discovered that LUC has altered Ag S, WSA, and MWD. Due to tillage and other cultural practices, Ag S, WSA, and MWD were significantly lower in CL and TP. However, the results confirm that native ecosystems (EF and DF) with a higher carbon content prevent such degradation, thereby resulting in good Ag S, WSA, and MWD.

Spatial patterns of soil stoichiometry and their responses to land use in a desertified area: A case study of China's Horqin Sandy Land

AbstractEcological stoichiometry facilitates the understanding of biogeochemical cycles by studying the balance among multiple elements in ecosystems. However, the spatial patterns of soil stoichiometry and their responses to land use in desertified land are unclear. In this study, we selected 525 sample points to collect topsoil (0–20 cm) samples throughout China's Horqin Sandy Land and measured soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP). We then calculated stoichiometric ratios (C:N:P). SOC (8.7 g kg−1), TN (0.9 g kg−1), and TP (0.3 g kg−1) were lower in this region than in Chinese and global terrestrial ecosystems due to aeolian desertification. SOC, TN, C:P, and N:P were significantly (p < 0.05) higher in grassland, followed by woodland, cropland, and sandy land. This sequence may result from the large number of dead roots that participate in the SOC turnover in grassland. TP was significantly higher in cropland due to fertilization. C:N did not differ significantly (p > 0.05) among grassland, woodland, and cropland because of the strong coupling relationship between SOC and TN. The values of SOC, TN, TP, C:P, and N:P in the Horqin Sandy Land were high in the north (dominated by mountain woodland and grassland) and were low in the south (dominated by desertified land). SOC, TN, and TP contents and C:N:P ratios were mainly affected by mean annual temperature (29.6%), land use (11.5%), and bulk density (11.4%) through their influence on soil microbial metabolism, litter and nutrient input, and soil structure, respectively. The results provide information on the overall changes in soil stoichiometry in the Horqin Sandy Land and its responses to land‐use changes, and can therefore guide ecological restoration in semiarid regions affected by desertification in the modern context of climate change.