Changes in biodiversity and ecosystem function during the restoration of a tropical forest in south China

Tropical forests continue to vanish rapidly,but few long-term studies have ever examined if and how the lost forests can be restored.Based on a 45-year restoration study in south China,we found that a tropical rain forest,once completely destroyed,could not recover naturally without deliberate restoration efforts.We identified two kinds of thresholds that must be overcome with human ameliorative measures before the ecosystem was able to recover.The first threshold was imposed primarily by extreme physical conditions such as exceedingly high surface temperature and impoverished soil,while the second was characterized by a critical level of biodiversity and a landscape context that accommodates dispersal and colonization processes.Our three treatment catchments(un-restored barren land,single-species plantation,and mixed-forest stand)exhibited dramatically different changes in biodiversity and ecosystem functioning over 4 decades.The mixed forest,having the highest level of biodiversity and ecosystem functioning,possesses several major properties of tropical rain forest.These findings may have important implications for the restoration of many severely degraded or lost tropical forest ecosystems.     

Analysis of Grassland Vegetation of the Southwest Heilongjiang Steppe （China） Using the Power Law

In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was the grass Stipa baicalensis Roshev. Grasslands with light, intermediate, and heavy grazing intensities were located 10, 5, and 2 km from a village, respectively. Villagers use the steppe to raise cattle, horses, sheep, and goats. Each of the three grasslands was surveyed by placing 100 quadrats （50 cm×50 cm） along a 50 m line transect. Each quadrat was divided into four equal areas （25 cm×25 cm; S-quadrats） and all plant species occurring in each of these smaller areas were identified and recorded. These data were summarized into frequency distributions and the percentage of S-quadrats containing a given species and the variance of each species were estimated. The power law was applied to these estimates. The power law was used to evaluate the spatial heterogeneity and frequency of occurrence for each species in the grassland community. The lightly grazed grassland exhibited high spatial heterogeneity （caused by large plant size）, the highest species diversity, and a high occurrence of S. baicalensis. In contrast, the heavily grazed grassland exhibited high spatial heterogeneity （caused by patchy populations of small plant size）, low species diversity, and a low occurrence of S. baicalensis. We judged that the heavily grazed grassland was overgrazed and exclusion of livestock from the degraded areas is necessary for recovery.     

Response of Polygonum viviparum species and community level to long-term livestock grazing in alpine shrub meadow in Qinghai-Tibet Plateau

Grazing by domestic herbivores is generally recognized as a major ecological factor and an important evolutionary force in grasslands. Grazing has both extensive and profound effects on individual plants and communities. We investigated the response patterns of Polygonum viviparum species and the species diversity of an alpine shrub meadow in response to long-term livestock grazing by a field manipulative experiment controlling livestock numbers on the Qinghai-Tibet Plateau in China. Here, we hypothesize that within a range of grazing pressure, grazing can alter relative allocation to different plant parts without changing total biomass for some plant species if there is life history trade-offs between plant traits. The same type of communities exposed to different grazing pressures may only alter relative species' abundances or species composition and not vary species diversity because plant species differ in resistant capability to herbivory. The results show that plant height and biomass of different organs differed among grazing treatments but total biomass remained constant. Biomass allocation and absolute investments to both reproduction and growth decreased and to belowground storage increased with increased grazing pressure, indicating the increasing in storage function was attained at a cost of reducing reproduction of bulbils and represented an optimal allocation and an adaptive response of the species to long-term aboveground damage. Moreover, our results showed multiform response types for either species groups or single species along the gradient of grazing Intensity. Heavy grazing caused a 13.2％ increase in species richness. There was difference in species composition of about 18％--20％ among grazing treatment. Shannon-Wiener (H') diversity index and species evenness (E) index did not differ among grazing treatments. These results support our hypothesis.     

Effect of cultivating croplands and grazing in arid grassland habitats on the conservation of melitaeine butterflies in a mountainous area in Northern China

In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different loca-tions, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterflies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and dis-continuous croplands within the patch has a significant effect on the population density of both spe-cies of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, comple-mented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effec-tively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategi-cally involved in proposing conservation plans for the target species in the future.     

Planting position and shade enhance native seedling performance in forest restoration for an endangered malagasy plant

The critically endangered tree Schizolaena tampoketsana is confined to a few diminished and degraded forest fragments on the Malagasy highlands. This habitat is vulnerable to loss due to frequent fires in the surrounding grassland that threaten to spread into the forest. One of these fragments is the focus a conservation project and here the managers aim to conserve S. tampoketsana by restoring its forest habitat to its former extent as evidenced by remnant woody plants. To inform this activity the survival and early-stage growth of seedlings of four locally native tree species were compared under contrasting conditions of proximity to the remaining forest and shade. After 12 months, seedlings of three species(Baronia taratana, Eugenia pluricymosa, Uapaca densifolia) survived better and experienced improved growth in height in grassland close to the existing forest rather than distant from it, and two survived better with shade rather than unshaded. A number of mechanisms could explain these results including reduced exposure to desiccating sunlight and winds and better soil and greater water availability close to the forest. The seedlings of one species(Nuxia capitata) survived well under all conditions. This study suggests that reforestation in these dry highlands is most feasible adjacent to remnant forest fragments and in microhabitats that minimize water loss, though young plants of some tree species may be capable of surviving in harsher conditions.     

The effects of different urban land use patterns on soil microbial biomass nitrogen and enzyme activities in urban area of Beijing, China

Soil microbes are affected by various abiotic and biotic factors in urban ecosystem due to land use change. The effects of different land use patterns on soil microbial properties and soil quality are, however, largely unknown. This study compared soil nutrient status, microbial biomass nitrogen and enzyme activities under five different land use patterns—nature forest, park, farmland, street green, and roadside tree sites at various soil depths in Beijing, China. The results showed that soil properties were significantly affected by urban land use patterns and soil depths in the urban environment. Compared to forest sites, soil nutrients were markedly decreased in other land use patterns, except the highest soil organic matter content in roadside tree sites in 0–10 cm soil layer. Soil microbial biomass nitrogen showed the order as follows: nature forest > park > farmland > street green > roadside tree in 0–10 cm soil layer, and it decreased along with the soil depth gradient. Furthermore, urease activity was highest in nature forest and lowest in street green and roadside tree soils in each depth, while the activity of protease ranged between 0.84 and 3.94 mg g^?1 with the peak appeared in roadside tree at 30–40 cm soil layers. Nitrate reductase activity was also extremely higher in street green than other land use patterns. Correlation analyses suggested that change of soil microbial biomass and enzyme activity in different land use patterns were mainly controlled by nutrient availability and soil fertility in urban soils.     

Effects of fire disturbance on the soil physical and chemical properties and vegetation of Pinus massoniana forest in south subtropical area

A variety of studies on the impact of fire disturbance on ecosystems has shown that the physical and chemical properties of soil after fire disturbance change notably. Meanwhile, little is known about the effects of different fire intensities on the soil properties and vegetation after fire disturbance, especially in the south subtropical area. In this paper, we analyzed the soil physical and chemical properties, vegetation species and species diversity of fire center, fire edge (which was burned a year ago) and non-burned Pinus massoniana plantation in Gaoyao, Guangdong province, China. The results showed that the soil conductivity, water content, total nitrogen, total potassium, and available potassium content of fire center were significantly higher than those of the non-burned land, and pH was higher than that of fire edge, whereas the available nitrogen, total phosphorus and organic matter content were much lower, which were generally existed in 0–10 cm soil layer and 10–30 cm soil layer. Changes of the soil properties of fire edge were similar with those of fire center, but less significant, and seemed to be more complex. Effects of burning on the vegetation of fire disturbance plots were found to be notable, species number and average height of plants of fire disturbance plots were lower than those of the non-burned plots, a difference of species diversity and uniformity were also shown, and finally, the composition of plant community also changed, e.g., pioneer species such as D. dichotoma, etc., dominated, and drought-resistant plants, heat-resistant plants and positive plants increased after burning.     

Effects of fire disturbance on the soil physical and chemical properties and vegetation of Pinus massoniana forest in south subtropical area

A variety of studies on the impact of fire disturbance on ecosystems has shown that the physical and chemical properties of soil after fire disturbance change notably. Meanwhile, little is known about the effects of different fire intensities on the soil properties and vegetation after fire disturbance, especially in the south subtropical area. In this paper, we analyzed the soil physical and chemical properties, vegetation species and species diversity of fire center, fire edge (which was burned a year ago) and non-burned Pinus massoniana plantation in Gaoyao, Guangdong province, China. The results showed that the soil conductivity, water content, total nitrogen, total potassium, and available potassium content of fire center were significantly higher than those of the non-burned land, and pH was higher than that of fire edge, whereas the available nitrogen, total phosphorus and organic matter content were much lower, which were generally existed in 0–10 cm soil layer and 10–30 cm soil layer. Changes of the soil properties of fire edge were similar with those of fire center, but less significant, and seemed to be more complex. Effects of burning on the vegetation of fire disturbance plots were found to be notable, species number and average height of plants of fire disturbance plots were lower than those of the non-burned plots, a difference of species diversity and uniformity were also shown, and finally, the composition of plant community also changed, e.g., pioneer species such as D. dichotoma, etc., dominated, and drought-resistant plants, heat-resistant plants and positive plants increased after burning.     

Localized treatments using commercial dust and liquid formulations of fipronil against Coptotermes formosanus （Isoptera： Rhinotermitidae） in the laboratory

Use of proper application methods and formulations of termiticides are im- portant to reduce their negative impact to the environment. In this study, we conducted laboratory experiments to determine the effect of localized treatments with commercial dust and liquid formulations of fipronil against Formosan subterranean termites, Coptoter- mes formosanus Shiraki. The test arena consisted of a specially designed 16-chambered structure with a center chamber connected to 5 foraging chambers that themselves were connected to 10 additional foraging chambers. One peripheral chamber received a liquid or dust treatment and termites were released in the center chamber. Results showed that 〉 91% of the termites were dead within the 9-d test period despite the localized treatment of only 1 foraging chamber. Termites that were still alive after 9 d were transferred to an untreated dish and held for 10 more days. The majority of those termites were dead and the rest were moribund on day 19. Regardless of the specific dish treated, both formulations of fipronil were found to be highly efficacious. Termites did not exhibit repellency to either formulation. Our results suggest that localized （or spot） treatment with either commer- cially available dust or liquid formulations of fipronil can be a viable option for control of a termite infestation where complete soil drenching is not desirable.     

Pattern analysis in landscape ecology: progress, challenges and outlook

Landscape pattern indices or landscape metrics, an important means in landscape pattern analysis, has resulted in the prosperity of landscape ecology. However, landscape pattern analysis was criticized recently for its poor correlation with ecological processes. In this paper, the current situation and challenges in landscape pattern analysis was elaborated, and the future of landscape pattern analysis was discussed. We believe that the landscape metrics is still the main method in spatial pattern analysis, and is important for landscape ecology. However, there are 3 challenges in landscape pattern analysis: (1) how to develop new methods by integrating explicit ecological sense in landscape pattern analysis? (2) How to link landscape pattern and ecological processes? (3) How to apply the theory of “matrix-patch-corridor” to practice? In future, 5 issues are to be addressed: (1) to develop a methodology to describe landscape pattern in a dynamic manner; (2) to explore the ecological sense of landscape pattern using a series of landscape metrics; (3) to develop new methods for landscape pattern analysis related to ecological processes; (4) to conduct landscape pattern analysis at multi-dimensions; (5) to explain the relationship between landscape pattern and ecological processes by multi-scale pattern analysis.     

Short‐term effects of low intensity fire on soil macroinvertebrate assemblages in different vegetation patch types in an Australian tropical savanna

Abstract Early dry season fires are a common land management regime employed across the tropical savannas of northern Australia. The rationale is that this reduces fuel loads and so reduces fire risk in the latter part of the dry season. Despite the acceptance of fire as a major management tool the ecological effects of fire remain uncertain. Vegetation patches and their associated macroinvertebrates play a critical role in the capture and recycling of water and nutrients. The aim of this study was to examine the responses of soil macroinvertebrates, within different types of vegetation patches, to early dry season fires in tropical savanna woodland in northern Australia. The abundance of major macroinvertebrate taxa and functional groups, and taxon richness were quantified in three vegetation patch types 2 weeks before and 2 weeks after burning. Termites dominated the soil macroinvertebrate assemblage sampled. Fire led to significant decreases in ant and spider abundances and overall taxon richness. Functional group analyses showed significant overall declines in the abundances of macropredators and litter transformers. There were also interactions between fire and patch type; in tree patches, fire significantly reduced total macroinvertebrate abundance, as well as the abundance of termites and ecosystem engineers. These changes in soil macroinvertebrates will potentially influence patch functionality, with important implications for soil processes and landscape health.     

Dynamics of species-rich upland hay meadows over 15 years and their relation with agricultural management practices

Questions: Has the species-rich vegetation of upland hay meadows been maintained under low intensity management imposed by an agri-environment scheme? Is the target plant community re-establishing where it has been modified previously by intensive agricultural practices? What combinations of management practices and soil properties are associated with changes towards or away from the target community? Location: The Pennines, northern England, UK. Methods: A survey of 116 hay meadows in 1987 was repeated in 2002 by recording plant species in permanent quadrats. Changes in community variables (species richness, Ellenberg values, upland hay meadow community coefficients) were analysed in species-rich, modified species-rich and degraded grassland types. Redundancy Analysis and Generalised Linear Models were used to show the relationship between management practices and soil properties and change in species composition and community variables. Results: Few sites contained the species-rich grassland type, and here forb richness declined. In the modified species-rich type, total and grass species richness increased but Ellenberg N-values also increased. Total and grass species richness increased in the degraded type and the community coefficient increased. Management was weakly related to change in species composition but showed clear relationships with the community variables. Re-establishment of the target species-rich community was more likely with late cutting, in the absence of cattle or prolonged spring grazing, and at lower soil nutrient status. Conclusion: The species-rich community was not maintained but some reversion occurred in degraded grassland. Inorganic fertiliser application and intensive spring grazing should be avoided and cutting delayed until late July.     

Grazing as a factor structuring grasslands in the Pyrenees

Questions: What are the relative roles of abiotic and grazing management factors on plant community distribution in landscapes? How are livestock type and stocking rate related to changes in vegetation structure and composition? Location: Sub‐alpine grasslands in the central and eastern Pyrenees. Methods: Multivariate analysis and variance partitioning methods were used to evaluate the relative roles of environmental factors in structuring vegetation composition and diversity patterns in three surveys on differently managed grasslands. Results: Vegetation composition within a region was affected by environmental factors hierarchically, changing first according to abiotic factors and then to grazing management. At landscape scales, abiotic factors explained two‐fold more variation in vegetation composition than grazing factors. Within landscape units, cattle grazing increased vegetation heterogeneity at landscape and patch scales, while sheep grazing favoured the presence of a specific set of species with high conservation value. Species composition was highly responsive to management variables compared to diversity components. Conclusions: The combination of sheep and cattle grazing at various stocking rates is an effective tool to preserve the diversity of plant species and communities within a region with a long tradition of livestock management, through the scaling up of effects by local processes occurring in patches at smaller scales.     

Floristic composition and spatial distribution assessment of montane mesophilous grasslands in the central Apennines,Italy: A multi-scale and diachronic approach

Abstract

Evaluation of past land use offers valuable information in seeking to understand the distribution patterns of plant communities, insofar as such activity may have altered soil features, causing anthropogenic soil patchiness and marked plant diversity both locally and regionally. This study sought to provide a general overview of the relationships between the different syntaxonomical units and the soil features in a sub-Mediterranean grassland landscape, starting from assessment of soil parameters. In addition, we wanted to verify whether soil features and hierarchical landscape assessments of grasslands under homogeneous grazing disturbance are sufficient to explain the floristic differentiation of the plant communities, and whether study of land use history helps explain the distribution patterns of these plant communities. A clear understanding of the relationships between environmental factors and the floristic composition of plant communities is a strong basis for future inquiries into how disturbance variations (grazing, mowing, manuring, etc.) and past land use variations have affected grassland structures. This study examined nine syntaxa that develop on semi-flat slopes or those with northern exposure.     

Biodiversity of semi‐arid Mediterranean grasslands: Impact of grazing and afforestation

Question: What is the impact of grazing and/or afforestation on grassland diversity, species composition and cover parameters? Location: Semi‐arid Mediterranean grasslands of Jordan. Methods: Vegetation, litter, bare soil and rock cover were compared among four management types – free grazing and protected from grazing with three levels of tree cover. Species composition, plant cover, species richness and evenness were used to evaluate differences in vegetation among management types. Species composition differences among management types were also investigated. Results: Semi‐arid Mediterranean grasslands harbour appreciable levels of plant biodiversity. Grazing did not affect plant diversity, indicating the high resilience against and adaptation to grazing; however,grazing affected species composition and cover parameters. Afforestation seems to protect soil through higher litter cover but its impact on plant biodiversity was negative and markedly affected species composition. Conclusions: Neither protection from grazing or massive afforestation alone are sufficient for conserving biodiversity in this system. A management model is suggested where the landscape should be maintained as a mosaic of four management types: complete protection from grazing, grazing rotation, planting sparse trees in eroded areas and revegetating degraded areas using native, herbaceous and grazing tolerant species.     

Traditional Cattle Grazing in a Mosaic Alkali Landscape: Effects on Grassland Biodiversity along a Moisture Gradient

Extensively managed pastures are of crucial importance in sustaining biodiversity both in local- and landscape-level. Thus, re-introduction of traditional grazing management is a crucial issue in grassland conservation actions worldwide. Traditional grazing with robust cattle breeds in low stocking rates is considered to be especially useful to mimic natural grazing regimes, but well documented case-studies are surprisingly rare on this topic. Our goal was to evaluate the effectiveness of traditional Hungarian Grey cattle grazing as a conservation action in a mosaic alkali landscape. We asked the following questions: (i) How does cattle grazing affect species composition and diversity of the grasslands? (ii) What are the effects of grazing on short-lived and perennial noxious species? (iii) Are there distinct effects of grazing in dry-, mesophilous- and wet grassland types? Vegetation of fenced and grazed plots in a 200-ha sized habitat complex (secondary dry grasslands and pristine mesophilous- and wet alkali grasslands) was sampled from 2006–2009 in East-Hungary. We found higher diversity scores in grazed plots compared to fenced ones in mesophilous- and wet grasslands. Higher cover of noxious species was typical in fenced plots compared to their grazed counterparts in the last year in every studied grassland type. We found an increasing effect of grazing from the dry- towards the wet grassland types. The year-to-year differences also followed similar pattern: the site-dependent effects were the lowest in the dry grassland and an increasing effect was detected along the moisture gradient. We found that extensive Hungarian Grey cattle grazing is an effective tool to suppress noxious species and to create a mosaic vegetation structure, which enables to maintain high species richness in the landscape. Hungarian Grey cattle can feed in open habitats along long moisture gradient, thus in highly mosaic landscapes this breed can be the most suitable livestock type.     

Restoration of native vegetation following exclosure establishment on communal grazing lands in Tigray,Ethiopia

Questions: Is plant species richness, diversity and above‐ground standing biomass enhanced after establishing exclosures on communal grazing lands? What factors influence the effectiveness of exclosures to restore degraded native vegetation in Tigray, Ethiopia? Location: Northern Ethiopia. Methods: We used a space‐for‐time substitution approach to detect changes in plant species richness, diversity and above‐ground standing biomass after conversion of communal grazing lands to exclosures. We selected replicated (n=3) 5‐, 10‐, 15‐ and 20‐year‐old exclosures and paired each exclosure with an adjacent communal grazing land to ensure that soil and terrain conditions were as similar as possible among each pair. Results: All exclosures displayed higher plant species richness, diversity and biomass than the communal grazing lands. Differences in plant species richness and biomass between an exclosure age and adjacent communal grazing land were higher in oldest than in youngest exclosures. In exclosures, much of the variability in plant species composition and biomass was explained by a combination of edaphic (total nitrogen, phosphorus, texture and soil pH) and site (precipitation and altitude) variables (R²=0.72–0.82). Edaphic and site variables also explained much of the variability in plant species composition in communal grazing lands (R²=0.76–0.82). Our study shows that all exclosures are at an early stage of succession. The increase in economically important indigenous shrub and tree species with exclosure age suggests that, with time, a valuable afromontane forest may develop. Conclusions: Establishment of exclosures on communal grazing lands is a viable option to restore degraded native vegetation. However, before expanding exclosures, the ecological consequences of additional exclosures should be investigated as further expansion of exclosures could increase grazing pressure on remaining grazing areas. Furthermore, consideration of edaphic and site variables will help optimize selection of areas for establishment of exclosures and enhance natural regeneration in exclosures in the future.     

Use of indigenous ecological knowledge of the Maasai pastoralists for assessing rangeland biodiversity in Tanzania

This paper incorporates the indigenous ecological knowledge (IEK) of the Maasai pastoralists and ecological methods to assess effects of grazing and cropping on rangeland biodiversity at macro‐ and micro‐landscape scales in northern Tanzania. The joint surveys with pastoralists identified indicator plant species and their associations with micro‐landscapes and livestock grazing suitability (i.e. for cattle and small ruminant grazing), while traditional calf‐pasture reserves (alalili pl. alalilia) were evaluated for preservation of rangeland biodiversity. The macro‐landscapes comprising the cool high plateau (osupuko pl. isipuki) and montane forest highland (endim) were included in the survey. At micro‐landscape scales, the osupuko was classified into uplands (orkung'u), slopes (andamata) and dry valley bottomlands (ayarata). The micro‐landscapes were assessed in terms of herbaceous plant species and woody species richness and risks of soil erosion. Biodiversity varied at both the macro‐ and micro‐landscape scales and in accordance with the land‐use types. Greater plant species diversity and less erosion risks were found in the pastoral landscapes than in the agro‐pastoral landscapes. The calf‐grazing pastures had greater herbaceous species richness than the non‐calf pastures, which in turn had more woody species. The study concludes that the indigenous systems of landscape classification provides a valuable basis for assessing rangeland biodiversity, which ecologists should incorporate into ecological surveys of the rangelands in East Africa in the future.     

Tropical forest recovery: legacies of human impact and natural disturbances

Land-use history interacts with natural forces to influence the severity of disturbance events and the rate and nature of recovery processes in tropical forests. Although we are far from an integrated view of forest recovery processes, some generalizations can be made. Recovery of forest structure and composition is relatively rapid following disturbances that primarily impact forest canopies, such as hurricanes. Recovery is considerably slower following disturbances that heavily impact soils as well as aboveground vegetation, such as bulldozing, heavy or long-term grazing, and severe fires, often with long-lasting effects on species composition. The landscape matrix plays a critical role in local recovery processes. Proximity of disturbed areas to remnant forest patches promotes more rapid recovery, which depends heavily on seed dispersal. Recovery of aboveground biomass is constrained by soil fertility and texture across regions as well as across soil types within a region. Restoration of soil fertility may be a prerequisite for forest recovery on sites with severely degraded soils. Despite evidence of rapid forest recovery following large-scale deforestation, many degraded areas of today's tropics will require human assistance to recover forest structure, species composition, and species interactions typical of mature tropical forests.