A comparison of some population density sampling techniques for biodiversity, conservation, and environmental impact studies

Twelve terrestrial and marine studies were conducted at various sites in Malaysia, Brazil, and the United States between April 1999 and February 2004. These data were analyzed using five density estimate techniques for stationary (non-motile) organisms including Stratified Random Sampling, Point-Center Quarter, Third Nearest Object, Weinberg, and Strong. The Strong method gave the most accurate density estimates of stationary animals and plants. Stratified Random Sampling ranked second best and the Third Nearest Object the third best. Belt or strip transects may be preferable but can be restrictive in some situations because of logistics and associated time constraints. Straight line measurements on reefs were 3–27% more accurate than reef slack line and reef contour measurements. Most study areas measured with the standardized Morisita index of dispersion were moderately aggregated. Results from the Third Nearest Object and Point-Center Quarter techniques indicate that the addition of more data to establish a density correction factor does not necessarily give more accurate estimates of density.     

Potential biodiversity map of bird species (Passeriformes): Analyses of ecological niche,environmental characterization and identification of priority conservation areas in southern Patagonia

Different methodologies try to identify priority conservation areas (PCA) to improve habitat conservation and decrease human pressures over bird species at coarse-scale. Map of potential biodiversity (PB) can identify PCA (high PB values) at different scale levels by considering ecological requirements and distributions through potential habitat suitability (PHS) models. The aim was to elaborate a map of PB of bird species based on PHS models to spatially identify PCA in Santa Cruz, Argentina. Moreover, we want to analysis species’ ecology requirements, and evaluate PB values and spatially identify PCA through two scale levels. We computed 47 models using Environmental Niche Factor Analysis (ENFA) on Biomapper software. Each model was visualized and combined to get a unique map of PB. We analyzed ecological requirements by specialization and marginality and PHS maps. Moreover, considering natural environments (regional level) and forest types’ cover (forest landscape level), we evaluated PB values using ANOVAs and identified PCA under different human pressures, using human footprint (HPF) map. Bird species related to Nothofagus forests were most specialist and exhibited a narrower potential distribution than grassland species. At regional level, Magellanic grass steppes displayed the highest PB values, where most of the PCA had high HPF values. At forest landscape level, ecotone N. antarctica forests had the highest PB values, where PCA with low HFP values were outside current protected networking. We conclude that combining PHS models and the map of PB allowed us to improve bird distribution studies and to assist biodiversity conservation strategies under human pressures.     

Improving biodiversity surrogates for conservation assessment: A test of methods and the value of targeted biological surveys

Aim

Conservation assessment and planning across extensive regions rely on the use of mapped or modelled surrogates because direct field‐based inventories of biodiversity rarely provide complete spatial coverage. Surrogates are assumed to represent spatial patterns in the distribution of biodiversity, yet the validity of this assumption is rarely evaluated. Here, we use data from new biological surveys targeting poorly known taxonomic groups across sparsely surveyed landscapes to test: (1) the performance of established and novel surrogates; and (2) the value of targeted survey data in further improving surrogate effectiveness.

Location

Continental Australia.

Methods

Surrogates were derived from either mapped land classifications (bioregions, vegetation types), or models of spatial turnover in biodiversity composition. Models were derived by linking best‐available biological observations to high‐resolution mapped climate, terrain and soil attributes using generalized dissimilarity modelling (GDM). The performance of surrogates was evaluated using survey data for eight biological groups collected as part of the Bush Blitz programme ( http://bushblitz.org ). For the GDM‐based surrogates, within‐ and cross‐taxon performance was first evaluated for models fitted to biological data available prior to Bush Blitz, and then for models enhanced through the addition of the Bush Blitz data.

Results

All of the tested surrogates performed significantly better than random across all eight biological groups. GDM‐based surrogates performed over 10% better on average than the best performing combination of mapped land classifications. The addition of Bush Blitz targeted data in GDM‐based surrogates led to further improvements in surrogate performance.

Main conclusions

Our results support continued investment in targeted biological survey programmes to enhance the performance of surrogates and ensure that surrogates represent a wider breadth of biodiversity. The strong performance of compositional turnover modelling, relative to mapped land classifications, suggests that this surrogate strategy deserves greater consideration in future conservation assessments and has potential for use in continental‐scale monitoring of biodiversity.

     

Establishing an ecological vulnerability assessment indicator system for spatial recognition and management of ecologically vulnerable areas in highly urbanized regions: A case study of Shenzhen,China

The extensive use of modeling and technologies such as a geographic information system (GIS) in ecological vulnerability assessment and the recognition of eco-environmentally vulnerable areas from the perspective of spatial positioning provide important complements to urban ecological space management research. This study establishes an ecological vulnerability assessment indicator system containing nine elements and twelve indicators with respect to ecological sensitivity, ecological pressure, and self-resilience. The range of ecologically vulnerable areas in a highly urbanized region is spatially recognized. Management strategies are proposed with regard to institutionalization and marketization. The results show that the ecological vulnerability in Shenzhen is good overall and that most areas are moderately vulnerable; the goal of space management is to enhance ecological function and prevent further expansion of the city as a threat to ecological security. Highly vulnerable areas are mainly distributed in the west and agglomerate with urban functional areas; it is suggested to delimit an ecological red line in this region and implement the most stringent “steel wire” control following the existing ecological protection law in China. Furthermore, this study proposes an ecological preparedness system suited for the particularity of the highly urbanized region in Shenzhen and attempts to introduce marketization into ecological restoration to solve the economic and social plight of ecological reconstruction in highly urbanized regions. The vulnerability assessment results objectively reflect the condition of the regional ecological environment, and the space management policy has implications for ecological protection, resource utilization, and sustainable development in similar cities.     

Optimization of economic policies and investment projects using a fuzzy logic based cost-effectiveness model of coral reef quality: empirical results for Montego Bay, Jamaica

 For effective mitigation of human impacts, quantitative models are required that facilitate a comprehensive analysis of the effects of human activity on reefs. Fuzzy logic procedures generate a complex dose-response surface that models the relationships among coral abundance and various inputs (e.g., physical damage, sedimentation, nutrient influx), within the context of the abiotic marine environment. This is linked to a nonlinear economic structure incorporating technical interventions (e.g., pollution treatment) and policy interventions (e.g., taxation) in eight economic sectors. Optimization provides insights into the most cost-effective means for protecting coral reefs under different reef quality targets. The research demonstrates that: (1) it is feasible to use fuzzy logic to model complex interactions in coral reef ecosystems; and, (2) conventional economic procedures for modeling cost-effectiveness can result in sub-optimal policy choices when applied to complex systems such as coral reefs. In Montego Bay, Jamaica, up to a 20% increase in coral abundance may be achievable through using appropriate policy measures having a present value cost of US$153 million over 25 years; a 10% increase is achievable at a cost of US$12 million. Accepted: 20 June 1999     

Sperm head morphometry in ejaculates of adult marmosets (Callithrix jacchus): A model for studying sperm subpopulations and among-donor variations

In humans and other mammals, sperm morphology has been considered one of the most important predictive parameters of fertility. The objective was to determine the presence and distribution of sperm head morphometric subpopulations in a nonhuman primate model (Callithrix jacchus), using an objective computer analysis system and principal component analysis (PCA) methods to establish the relationship between the subpopulation distribution observed and among-donor variation. The PCA method revealed a stable number of principal components in all donors studied, that represented more than 85% of the cumulative variance in all cases. After cluster analysis, a variable number (from three to seven) sperm morphometric subpopulations were identified with defined sperm dimensions and shapes. There were differences in the distribution of the sperm morphometric subpopulations (P < 0.001) in all ejaculates among the four donors analyzed. In conclusion, in this study, computerized sperm analysis methods combined with PCA cluster analyses were useful to identify, classify, and characterize various head sperm morphometric subpopulations in nonhuman primates, yielding considerable biological information. In addition, because all individuals were kept in the same conditions, differences in the distribution of these subpopulations were not attributed to external or management factors. Finally, the substantial information derived from subpopulation analyses provided new and relevant biological knowledge which may have a practical use for future studies in human and nonhuman primate ejaculates, including identifying individuals more suitable for assisted reproductive technologies.