Effects Of Human Use Research Articles

Vegetation structure and effects of human use of the dambos ecosystem in northern Mozambique

The Niassa National Reserve (NNR) is the most extensive conservation area in Mozambique and the third largest in Africa, encompassing 42,000 km2 of endemic miombo vegetation. Dambos wetlands occur within the wooded grassland and grassland vegetation of NNR and provide a wide range of Ecosystem Services (ES), including life support for animal species, regulation of water flow and prevention of soil erosion. It also generates income for the livelihoods of local communities by providing land for agriculture and harvesting of non-timber products. The dynamics of these ecosystems is poorly understood despite the contribution of the dambos to global biodiversity and ES. This research is the first preliminary assessment of the vegetation structure and composition of six dambos within NNR, selected using Google Earth, MODIS satellite images and an exploratory field visit. Field data collection was performed using a two-stage systematic sampling approach, along transect lines of 100 × 10 m (0.1 ha), perpendicular to the dambos' flow. Square plots of 0.25 m2 were established for grass survey within the transects where grass vegetation was measured, counted and identified. Data were analyzed with R software. The sociological position of each species was analyzed with regard to the vertical structure while for horizontal structure, the abundance, dominance, frequency and Importance Value Index (IVI) were determined. In order to understand the differences between dambos, evenness (H) and reciprocal of Simpson's heterogeneity index (Hill's N2) were calculated. Principal Coordinates Analysis (PCoA) and Cluster Analysis were also used to characterize the surveyed species communities. A total of 58 transects (5.8 ha) and 336 subplots were assessed, recording 110 woody and 73 grass species, respectively. The most common tree species were Vitex doniana, Burkea africana, Syzygium cordatum and Annona senegalensis, while for grass vegetation the most abundant species were Andropogon eucomus and Helictotrichon turgidulum. According to the IVI, the most dominant tree and shrub species were V. doniana, Pseudolachnostylis maprouneifolia, A. senegalensis and S. cordatum. Homogeneity (Hill's N2 = 18.92) and evenness (H = −4.27) were, on average, low in all dambos. Dambo 2 was the most heterogeneous (Hill's N2 = 18.21) while dambo 1 was the least heterogeneous (Hill's N2 = 5.71). Dambo 6 was most equitable (H = −1.35) whereas dambo 2 the least equitable (H = −3.72). Using species abundance and based on PCoA and cluster analysis, four main groups of dambos were identified based mainly on the water gradient, with data variation captured by the first three axes reaching almost 83%. The p-value (0.42), suggested no significant differences between species communities in the dambos, and thus, human disturbances appear not to be enough to modify dambos microenvironment. Accordingly, the results suggest that human activities, at this level, do not necessarily affect the structure and diversity of dambos in the NNR. The results also suggest that the species A. senegalensis, Combretum psidioides, Crossopteryx febrifuga, Protea nitida, P. maprouneifolia and S. cordatum can be used as indicator dambo species in NNR, with high likelihood of occurrence.

Assessing Land Use Change and Its Impact on Ecosystem Services in Northern Thailand

Ecosystem services are highly vulnerable to a number of impacts due to the complex effects of human use of natural resources and subsequent land use change. Assessment of the impact of change in land use with respect to ecosystem services is necessary in order to implement appropriate land uses that enhance ecosystem services. This study analysed the impact of change in land use on ecosystem services using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model to map and quantify a set of ecosystem services, namely sediment retention, water yield, carbon stock, and habitat quality, in northern Thailand, which has experienced substantial policy induced land use change. The study also assessed the changes in land use from 1989 to 2013 and their impact on overall ecosystem services using GIS. Increased rubber plantation cultivation and built-up areas resulting in reduced forest cover were the major changes found in land use in the area. The results of the study show a general decrease in ecosystem services for the study period in the watershed, in particular, a negative impact on ecosystem services was observed in agricultural areas. The study findings on spatial and temporal distribution of ecosystem services can help guide the development of appropriate land use options to enhance ecosystem services.

Effect of human use, season and habitat on ungulate density in Kanha Tiger Reserve, Madhya Pradesh, India

Conservation practitioners require strata specific, seasonal species densities for habitat management. Herein, we use stratified distance sampling in Kanha Tiger Reserve (KTR) with 200 spatial transects and an effort of 1200 km walk in the year 2013. Analysis was done to access (a) impact of human use and (b) effect of habitat and season on ungulate densities in KTR. While a single detection function for each species was used for estimating density within human-restricted core and multiple use buffer of KTR, species-specific seasonal detections were modelled for each habitat. Ungulate biomass was 4.8 times higher in the core area compared with the buffer zone. The core supported a herbivore density and biomass of 50 ± 4.80/km2 and 26,806 ± 2573 kg/km2, respectively. Chital were found to be most abundant, having a density of 30.1 ± 4.34/km2 and contributing 33 % of the biomass with a habitat preference for grasslands (106 ± 39/km2) in summer and winter. Sambar had highest density (15.4 ± 3.34/km2) in bamboo-mixed habitat, in both seasons. Gaur contributed 39 % of the ungulate biomass and showed a seasonal shift in density from sal forests (9.65 ± 3.55/km2) in summer to miscellaneous forests (8.13 ± 1.94/km2) in winter. Barasingha were restricted to grasslands with similar summer and winter densities of 1.56 ± 0.76/km2. Chousingha were rare (0.1 ± 0.04/km2), found mostly in miscellaneous forests and plateau grasslands. Grassland and bamboo-mixed forests supported 58 % of the total ungulate biomass. Management for an optimal habitat mosaic that maintains ungulate diversity, addresses the specific needs of endangered species and maximizes ungulate biomass is recommended.

Intense use of woody plants in a semiarid environment of Northern Ethiopia: Effects on species composition, richness and diversity

Human influences affect plant species diversity and composition in many tropical forest ecosystems. We assess the effects of human use of woody plants on plant species composition and diversity in an intensively used open-access forest in Northern Ethiopia, and compare these community attributes with those of relatively intact forest patches. In each of 90 20 × 20 m plots in the open-access forest, we counted the number of woody plant species in different growth stages, and compared with those of 48 same-sized plots in nearby intact forest patches. Forest utilisation resulted in major shifts in dominance, with the dominant species in relatively intact forests being absent in open-access forest, whereas those species dominant in the open-access forest were absent from intact forests. Open-access forest had a lower total number of species, individuals and beta diversity than relatively intact forests. Intensive forest utilization has resulted in the dominance of disturbance-tolerant native and invasive species. Opuntia ficus-indica, regarded as a problem weed in Ethiopia, was abundant in the open-access forest. Dominance of a few species in the open-access forest could cause local and landscape-scale species loss. Relatively intact forest patches are therefore important for biodiversity conservation and ecological restoration in northern Ethiopia.

Influence of Human Pressure on Forest Resources and Productivity at Stand and Tree Scales: The Case Study of Yunnan Pine in SW China.

This paper examines human impact on stands and individual trees of Pinus yunnanensis growing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province, China. In an effort to assess whether use of these forests was sustainable, we examined the effects of human use in two ways. First, we directly measured the effect of cutting branches, for fuel and fodder, on tree growth. We hypothesized that branch cutting would negatively impact tree growth. We established 12 plots on four hills and compared 14 pairs of trees, one tree in each pair with an apparently full crown and the other with a considerable portion of the crown removed. Second, we assessed stand and tree properties over a 500 m elevation gradient above the villages where we hypothesized that as elevation increases, stand and tree properties should show fewer human impacts. Although extensive branch cutting reduced the live crown, tree height and diameter, compensatory processes likely enabled trees to recover and to add basal area increments (BAIs) similar to those added by trees with full crowns. Trees and stands close to villages showed less growth and lower basal areas, respectively, than stands and trees at intermediate or distant elevations from villages. Areas relatively close to the villages showed considerable effects of human-related disturbances such as branch cutting, grazing, tree and shrub removal, losses of litter, and human and animal trails. Such areas had increased soil erosion and often loss of the 'A' horizon. Stands close to villages had younger trees, lower stand basal areas, smaller basal area increments, and more stumps. Our results suggest an increasingly vulnerable interface between occupants of these two villages and their surrounding forests.

Effects of recreational use on branchiopod egg and ephippia density, Black Rock Desert-High Rock Canyon emigrant trails National Conservation Area, Nevada, USA

Numerous plays playas occur on valley floors of endorehic basins in arid regions of the western USA. Their openness makes them attractive for hiking, vehicle travel, military, and other uses when dry. Branchiopod crustacean dormant egg banks survive in these systems and are a rich food resource for migrating birds. Brachniecta gigas Lynch, 1937, B. mackini Dexter, 1956, and Lepiduras lemmoni Holmes, 1895, and Moina cf. macrocopa (Straus, 1820) occur in the Black Rock Desert playa, Nevada, USA. We collected playa egg bank samples to determine effects of human use in three studies. We compared intact egg and ephippia density in virgin playa areas with: 1) a heavily used vehicle track, and 2) recreational camping and vehicle activity mitigated by dust abatement in Black Rock City (site of the Burning Man Festival). We also attempted to quantify changes in intact egg and ephippia density through repeated vehicle travel over a track on virgin playa. We found no observed decrease in intact egg or ephippia density attributed to incrementally increased vehicle travel over virgin playa, which may be attributed to strength of the playa substrate matrix. Differences in intact egg and ephippia density were substantially lower in heavily used vehicle tracks than in adjacent playa, but differences were not statistically significant. Density of intact eggs and ephippia in Black Rock City were lower following the festival, but differences were statistically significant only for eggs in camping areas and not roads. Weak effects observed on these roads may be attributed to dust abatement that maintained substrate density.

Managing visitor sites in Svalbard: from a precautionary approach towards knowledge-based management

Increased tourism in the Arctic calls for more knowledge to meet management challenges. This paper reviews existing knowledge of the effects of human use on vegetation, fauna and cultural heritage in Svalbard, and it addresses the need for site-specific knowledge for improved management. This paper draws upon scientific studies, knowledge held by management authorities and local people, the Governor’s database on visitors and visited sites and our own data from landing sites we visited. There is a certain level of basic knowledge available, allowing us to roughly grade the vulnerability of sites. However, there is a thorough lack of site-specific data related to the management of single locations or groups of similar locations. Future research needs to address specific on-site challenges in the management of visitor sites. Relevant management models and measures are discussed.We contend that a shift away from a blanket application of the precautionary principle and towards a more integrated, site-specific and evidence-based management plan will contribute to more trusted and reliable, and thereby acceptable among stakeholders, decisions in the management of growing tourism activity in Svalbard. Keywords: Arctic; resource management; planning; tourism (Published: 4 May 2012) Citation: Polar Research 2012, 31 , 18432, http://dx.doi.org/10.3402/polar.v31i0.18432

The effect of human use of sandy beaches on developmental stability ofTalitrus saltator(Montagu, 1808) (Crustacea, Amphipoda). A study on fluctuating asymmetry

AbstractIn recent years, there has been an increasing intensity of human use of coastal areas in Galicia (NW Spain). Actually, there is great concern about rapid and unplanned urban and industrial development on certain locations, as this can generate adverse impacts on those areas. In this study, we selected three sandy beaches along the Galician coast (Chanteiro, Insuela and Valieros) facing different levels of anthropic pressure, and we analysedTalitrus saltatorindividuals with the aim of elucidating whether anthropogenic pressures on beaches such as tourism or pollution have an influence on the incidence of morphological developmental alterations in sandhoppers in the field. Specifically, levels of fluctuating asymmetry were selected as indicators of environmental stress. Results of two sampling dates (May and September) show that individuals collected at the most touristy and polluted beach were those showing the highest asymmetry values, although results were only statistically significant for samples collected during spring. Results are in accordance with the hypothesis that beach management and pollution reduce symmetry in sandhoppers living in altered beaches.

Abiotic factors determining vegetation patterns in a semi-arid Mediterranean landscape: Different responses on gypsum and non-gypsum substrates

In arid and semi-arid regions water availability is the main factor determining vegetation patterns. On gypsum outcrops, vegetation is also conditioned by soil physical (i.e. surface crust) and chemical (i.e. ion unbalance) restrictions, which promote a highly specialist and endemic gypsophile flora. Topographical and climatic variability affect the rigors of gypsum soil environment, and thus, plant community distribution along environmental gradients can differ between gypsum and non-gypsum substrates. The aim of the paper was to evaluate the relative importance of different abiotic factors as drivers of plant communities in gypsum and non-gypsum substrates. While non-gypsophile vegetation is expected to be determined mainly by aridity, gypsophile vegetation could show more complex patterns, following the relaxation of the rigors of gypsum soil under environmental gradients such as steep slopes and mesic conditions. We compared the relationships between presence and cover of three plant communities (open woodland, dwarf-shrubland and garrigue) on gypsum and non-gypsum substrates with environmental factors, after removing the effect of human use. Generalized additive models (GAM) and generalized linear models (GLM) were employed. Results showed that xeric conditions inhibited development and recovery of vegetation, but plant communities on gypsum substrate did not always respond in the same way as non-gypsum vegetation. While the degree of aridity (determined by precipitation and temperature) conditioned non-gypsum vegetation strongly, favouring less developed plant communities, topographical factors (slope aspect and angle) were the main determinants of gypsum plant community patterns. We conclude that gypsum substrate determines strongly the plant community patterns in a semi-arid Mediterranean landscape, as it can be observed by the strong response of gypsophile vegetation to the relaxation of the rigors of gypsum soils with topography (i.e. steep and north oriented slopes).

Recovery of a Subtropical Dry Forest After Abandonment of Different Land Uses1

ABSTRACTWe studied the ecological characteristics of 45–50‐yr‐old subtropical dry forest stands in Puerto Rico that were growing on sites that had been deforested and used intensively for up to 128 yr. The study took place in the Guánica Commonwealth Forest. Our objective was to assess the long‐term effects of previous land use on this forest—i.e., its species composition, structure, and functioning. Previous land‐use types included houses, farmlands, and charcoal pits. Stands with these land uses were compared with a nearby mature forest stand. The speed and path of forest recovery after deforestation and land‐use abandonment depended on the conditions of the land. Study areas where land uses had removed the forest canopy and altered soil conditions (houses and farmlands) required a longer time to recover and had a different species composition than study areas where land uses retained a forest canopy (charcoal pits). Different forest attributes recovered at different rates. Crown area index, stem density, and litterfall rate recovered faster than stemwood and root, biomass, tree height, and basal area. Where previous land uses removed the canopy, Leucaena leucocephala, a naturalized alien pioneer species, dominated the regrowth. Native species dominated abandoned charcoal pits and mature forest. The change in species composition, including the invasion of alien species, appears to be the most significant long‐term effect of human use and modification of the landscape.

Landscape change under indirect effects of human use: the Savanna of Central Chile

The Chilean Intermediate Depression to the north of Santiago has experienced a physiognomical transformation from a Prosopis chilensis woodland to an Acacia caven savanna. Today P. chilensis trees are scarce and belong mostly to the larger size classes. By contrast A. caven seems to reproduce frequently and its populations consist of individuals of all size classes. In this paper we document these changes and report the results of tests aimed at determining the causes of these physiognomical changes. We found that livestock, leporids, introduced Mediterranean forbs and agriculture account for differences in seed dispersal and survival of A. caven and P. chilensis, which can explain the documented changes in the Chilean landscape.

Effect of Human Use of Energy on Climate

Effect of Human Use of Energy on Climate

Effect of Human Use of Energy on Climate

Effect of Human Use of Energy on Climate

Nonfood uses of plants in Usambara

The attempt here has been to discuss Shambaa use of wild nonfood plants primarily in terms of utility, but also with some attention to principles of classification and of the effects of human use of plants on the wider environment. The local system of classification emphasizes those plants which are useful to people. There are many of these, which may be surprising in an area that has been undergoing commercialization and socio-economic change since the early years of this century (P. Fleuret, 1979). Natural systems still provide the Shambaa with many useful, even essential products. But those plants that are useful are also being used up, and continued exploitation has ramifications for the other components of the ecosystem: fish vanished from the streams, wild date palms and tree ferns vanishing, deforestation, erosion, fuelwood shortages, increasing prices for many natural products. By all indications, the most crucial effects of human exploitation have occurred within the last 100 years. Contemporary accounts by missionaries and explorers describe the area as “... abound[ing] in forests of fine timber ...” (Krapf, 1860) or cite oral traditions indicating that the most seriously deforested areas of today were under forest just prior to the turn of the century. (Data obtained from Lushoto District files lodged at the Tanzania National Archives, Dar es Salaam.) As recently as 1975, one author, in writing of Usambara, suggested that a solution to agricultural crisis (especially land shortage) was to open the remaining forest reserve to human settlement and cultivation (Cliffe, 1975, pp. 149–150). This suggestion does not take into account the fact that the natural vegetation of Usambara continues to provide its residents with a great many vital materials and implements, even though human use of these resources is approaching, or has even reached, a critical point in terms of ecological consequences. Efforts should be made to preseve, not destroy, this vital natural resource.