遥感主体图的准确度对景观生态学研究的影响

用各种案例系统地解释了遥感数据分类误差对景观指数误差的必然影响。一方面 ,遥感数据在各种时间和空间尺度上为景观生态学研究提供必需的土地类型数据 ;另一方面 ,遥感技术的灵活性和复杂性可以产生出各种质量的土地类型数据。但景观生态学方面的用户对土地类型数据基本上是没有选择地使用 ,甚至是不知好坏地使用 ,所以景观生态学的发现和结论具有不可避免的任意性。总结了在各种情况下景观指数的变动区间 ,指出了现实较低的遥感数据的分类准确度会引起更低的景观指数的准确度 ,当进行景观变化分析时 ,这种误差的放大效应将更加明显。当前 ,人们对除面积以外的景观指数的误差仍然束手无策 ,尽可能地提高遥感数据的分类准确度是唯一力所能及的办法。     

森林生态系统生物物理参数遥感反演研究进展

论述了利用遥感技术反演推算森林生态系统主要生物物理参数：叶面积指数、吸收光合有效辐射、净第一性生产力和生物量的技术、方法和模型及各个参量之间的相互关系研究进展,阐述了各研究方法、模型的特点、优势及局限性。特别论述了净第一性生产力的森林冠层光合作用理论模型基础、微波遥感估算森林生物量的应用优势和理论模型,展示了遥感技术在森林生态学研究中广阔的应用前景,同时也指出现有研究中各生物物理参数的定量遥感估算还有待进一步深入研究。     

Population decline but increased distribution of an invasive ant genotype on a Pacific atoll

Populations of invasive species are often studied when their effects are perceived as a problem. Yet observing the dynamics of populations over longer time periods can highlight changes in effects on invaded communities, and assist with management decisions. In this study we revisit an invasion of the yellow crazy ant (Anoplolepis gracilipes) in the Tokelau archipelago to determine if the distribution and abundance of the ant has changed ~7 years after surveys completed in 2004. We were particularly interested in whether populations of a previously identified invasive haplotype (D) had increased in distribution and abundance, as this haplotype was implicated in negative effects on resident ant communities. Indeed, haplotype D populations have become more widespread since the initial survey, more likely owing to new introductions or movement by humans, rather than intrinsic characteristics of the haplotype. We also found that despite no significant change in the abundance of A. gracilipes overall, haplotype D populations have declined in abundance. Residents of the Tokelau atolls no longer consider the ant to be a pest as they did 7 years ago, when populations of this ant interfered with their food production and many other aspects of daily life. We observed no significant differences between A. gracilipes invaded and uninvaded communities, which suggests that the ant is at a level of abundance below which significant negative ecological effects may occur. Population declines of invasive species are not infrequent, and understanding these population dynamics, particularly the underlying mechanisms promoting population declines or stabilisation, should be a high priority for invasion ecology.     

Factor analysis and classification of remotely sensed data for monitoring tidal flats

Interest in using remote sensing techniques, principally those involving satellite, in Wadden Sea research has centred on attempting a classification of the various sediment surface types present. Unlike most recent studies which have used mainly Landsat Multispectral Scanner data, we have assessed the feasibility of using Landsat Thematic Mapper data, which in conjunction with time series aerial photography, forms the basis of a strategy for remotely sensing the Wadden Sea. This paper focusses on an approach for extracting potentially “hidden” within-pixel information from multispectral data sets. A hierarchical (unsupervised) classification of a Thematic Mapper image successfully classified five different classes, including land, saltmarsh, water, cloud and tidal flat areas. This procedure thus enabled a “masking-out” of all classes other than those classified as tidal flat, following which a factor analysis was used to determine the minimum number of independent factors necessary to explain the observed variation in the signal received by the satellite. Three factors accounted for a total of 82% of the variation in all seven TM channels. Preliminary studies of the primary factor (score) image shows a good correlation with existing latterday cartographic data. Considering the proximate relationship between topography and other important biotic and abiotic sedimentary characteristics, this approach may prove valuable for future applications of satellite data for monitoring long-term change in physical and thus biological Wadden Sea characteristics. Ongoing research efforts are focussing on a classification and quantification of sub-pixel patchiness using aerial photography and ground surveys. The approaches taken and results obtained to date are discussed. Presented at the VI International Wadden Sea Symposium (Biologische Anstalt Helgoland, Wattenmeerstation Sylt, D-2282 List, FRG, 1–4 November 1988)     

A field based statistical approach for validating a remotely sensed mangrove forest classification scheme

Amongst the most threatened ecosystems on Earth, mangrove forests are also one of the more difficult to work in due to their growth in mud and open water coastal zones and their dense tangled stems, branches and prop roots. Consequently, there has been an impetus to employ remotely sensed imagery as a means for rapid inventory of these coastal wetlands. To date, the majority of mangrove maps derived from satellite imagery utilize a simple mangrove classification scheme which does not distinguish mangrove species and may not be useful for conservation and management purposes. Although more elaborate satellite based mangrove classification schemes are being developed, given their enhanced complexity they deserve additional justification for end users. The purpose of this study was to statistically examine the appropriateness of one such classification scheme based on an inventory of field data. In January of 2007 and May of 2008, 61 field sample plots were selected in a stratified random fashion based on a previous classification of a degraded mangrove forest of the Isla La Palma (Sinaloa, Mexico) using Landsat TM5 data. Unlike other previous Landsat TM based classifications of this region, which simply identified the mangrove forests as one class, the mangroves were classified (i.e. mapped) according to four conditions; healthy tall, healthy dwarf, poor condition, and dead mangroves. Within each sample plot, all mangroves of diameter of breast height (dbh) greater than 2.5 cm were identified and their height, condition and dbh recorded. An estimated Leaf Area Index (LAI) value also was obtained for each sample and the shortest distance from the center of each sample plot to open flowing water was determined using a geographic information system (GIS) overlay procedure. These data were then used to calculate mean values for the four classes as well as to determine stem densities, basal areas, and the Shannon–Wiener diversity index. In order to assess the appropriateness of this mangrove classification scheme a discriminant analysis approach was then applied to these field data. The results indicate this forest has undergone severe degradation, with decreasing mean tree heights, mean dbh and species diversity. In regards to the discriminant analysis procedure, further classification of these field plots and cross-validation based on these significant variables provided high classification accuracy thus validating the appropriateness of the satellite based image classification scheme. Moreover, the discriminant analysis indicated that the estimated LAI, mean height, and mean dbh are significant in the separation of the classification of mangrove forest condition along these field sample plots.     

Combining geostatistical models and remotely sensed data to improve tropical tree richness mapping

Information on the spatial distribution and composition of biological communities is essential in designing effective strategies for biodiversity conservation and management. Reliable maps of species richness across the landscape can be useful tools for these purposes. Acquiring such information through traditional survey techniques is costly and logistically difficult. The kriging interpolation method has been widely used as an alternative to predict spatial distributions of species richness, as long as the data are spatially dependent. However, even when this requirement is met, researchers often have few sampled sites in relation to the area to be mapped. Remote sensing provides an inexpensive means to derive complete spatial coverage for large areas and can be extremely useful for estimating biodiversity. The aim of this study was to combine remotely sensed data with kriging estimates (hybrid procedures) to evaluate the possibility of improving the accuracy of tree species richness maps. We did this through the comparison of the predictive performance of three hybrid geostatistical procedures, based on tree species density recorded in 141 sampling quadrats: co-kriging (COK), kriging with external drift (KED), and regression kriging (RK). Reflectance values of spectral bands, computed NDVI and texture measurements of Landsat 7 TM imagery were used as ancillary variables in all methods. The R² values of the models increased from 0.35 for ordinary kriging to 0.41 for COK, and from 0.39 for simple regression estimates to 0.52 and 0.53 when using simple KED and RK, respectively. The R² values of the models also increased from 0.60 for multiple regression estimates to 0.62 and 0.66 when using multiple KED and RK, respectively. Overall, our results demonstrate that these procedures are capable of greatly improving estimation accuracy, with multivariate RK being clearly superior, because it produces the most accurate predictions, and because of its flexibility in modeling multivariate relationships between tree richness and remotely sensed data. We conclude that this is a valuable tool for guiding future efforts aimed at conservation and management of highly diverse tropical forests.     

Host tolerance,not symbiont tolerance,determines the distribution of coral species in relation to their environment at a Central Pacific atoll

Tolerance of environmental variables differs between corals and their dinoflagellate symbionts (Symbiodinium spp.), controlling the holobiont’s (host and symbiont combined) resilience to environmental stress. However, the ecological role that environmental variables play in holobiont distribution remains poorly understood. We compared the drivers of symbiont and coral species distributions at Palmyra Atoll, a location with a range of reef environments from low to high sediment concentrations (1–52 g dry weight m⁻² day⁻¹). We observed uniform holobiont partnerships across the atoll (e.g. Montipora spp. with Symbiodinium type C15 at all sites). Multivariate analysis revealed that field-based estimates of settling sediment predominantly explained the spatial variation of coral species among sites (P < 0.01). However, none of the environmental variables measured (sedimentation, temperature, chlorophyll concentration, salinity) affected symbiont distribution. The discord between environmental variables and symbiont distributions suggests that the symbionts are physiologically tolerant of the variable environmental regime across this location and that the distribution of different host–symbiont combinations present is largely dependent on coral rather than Symbiodinium physiology. The data highlight the importance of host tolerance to environmental stressors, which should be considered simultaneously with symbiont sensitivity when considering the impact of variations in environmental conditions on coral communities.     

基于多光谱影像的森林树种识别及其空间尺度响应

当前,不同空间分辨率卫星影像对森林类型识别结果中普遍存在的尺度效应,而且纹理参量对不同尺度下树种识别精度的影响仍缺乏广泛认知.本研究以中国东北旺业甸林场为研究区,采用观测时相同步、地理坐标匹配的GF-1 PMS、GF-2 PMS、GF-1 WFV,以及Landsat-8 OLI卫星传感器数据组成空间尺度观测序列(1、2、4、8、16、30 m),并结合支持向量机(SVM)模型,探讨了区域内5种优势树种遥感识别结果的尺度变化规律及其纹理特征参数的影响,同时检验了基于尺度上推转换影像的树种识别结果差异.结果表明: 影像空间分辨率对区域树种识别结果具有显著影响,其中,研究区森林树种识别的最佳影像分辨率为4 m,当分辨率降低至30 m时,树种识别结果最差.在1～8 m影像分辨率范围内,增加纹理信息能够显著提高不同优势树种的识别精度,使总分类精度提升了2.0%～3.6%,但纹理信息对16～30 m影像的识别结果没有显著影响.与真实尺度卫星影像相比,基于升尺度转换影像的树种识别结果及其尺度响应特征存在显著差异,表明在面向多个空间尺度的遥感观测和应用研究中,需要采用真实分辨率影像以确保结果的准确性.     

In situ and laboratory studies on the behaviour and survival of Pacific salmon (genus Oncorhynchus)

Juvenile Pacific salmon display a marked surface water orientation during downstream migration, estuarine and nearshore coastal rearing phases. Many estuaries in British Columbia are vertically stratified with a shallow, well-defined halocline which can restrict the dispersion of wastes discharged into less saline surface waters and impose constraints upon aquatic organisms. In situ experiments in an estuary receiving a surface discharge of treated pulp mill wastes, revealed conditions which were lethal to underyearling salmon at, and below the halocline (4.0–6.5 m depth). Behavioural bioassays determined that juvenile chinook salmon were biased towards the water surface and avoided waters at depth. Dissolved oxygen was the variable which affected this distribution most significantly. Surface waters receiving effluent from another pulp mill were lethal to juvenile salmon within 350 m, and a significant vertical avoidance response occurred within 350–950 m of the outfalls. The behavioural response was significantly correlated with in situ temperature, pH and colour (effluent).As a complement to field experiments we developed a 4500 l water column simulator (WCS) to examine salmon behaviour in the laboratory. We investigated the surface water orientation behaviour of juvenile salmon in relation to variations in salinity and dissolved oxygen. Under simulated vertically stratified estuarine conditions, the fish moved freely between overlying fresh water and salt water. Induction of hypoxic conditions in fresh water elicited a downward distribution shift towards the halocline and oxygenated, but more saline, waters. Avoidance reactions (50% level) occurred consistently up to 7–8 mg · l^–1 dissolved oxygen. Salmon continued to examine the hypoxic freshwater zone despite sub-optimal conditions.     

浙江天童国家森林公园景观的遥感分类与制图

利用Landsat-TM多时相数据,采用非监督分类方法,对浙江省天童国家森林公园的景观进行分类。并利用野外实地调查的数据进行检验和校正。结果表明,天童国家森林公园范围内的景观可分为常绿阔叶林、成熟常绿阔叶林、次生常绿-落叶阔叶林、山脊常绿-落叶阔叶林、谷地常绿-落叶阔叶林、林缘灌丛、次生灌丛、针叶林(杉木)、竹林、生长作物的农田／菜园地、旱地、裸土、居住区、水体14个类型,这14个景观类型,根据植物群落学分类的群落复合体(cammunity complex)和群落复合体的地-综合群落学(Geo-synsociology)的方法,归并为山坡常绿阔叶林、常绿落叶阔叶混交林、人工林(针叶林、竹林)、农田、水体、居住区6个景观单元。在景观分类和合并的基础上,对天童国家森林公园的景观进行了制图。     

In situ ammonia production as a sanitation agent during anaerobic digestion at mesophilic temperature

Aim: To measure the sanitizing effect of mesophilic (37°C) anaerobic digestion in high ammonia concentrations produced in situ. Methods and Results: Indicator organisms and salmonella were transferred to small‐scale anaerobic batch cultures and D‐values were calculated. Batch cultures were started with material from two biogas processes operating at high (46 mmol l^?1) and low (1·6 mmol l^?1) ammonia concentration. D‐values were shortened from c. 3 days to <1 day for the bacteria. MS2 had the same D‐value (1·3 days) independent of ammonia concentration whereas ΦX174 and 28B were faster inactivated in the control (1·1 and 7·9 days) than in the high ammonia (8·9 and 39 days) batch cultures. Conclusion: Running biogas processes at high levels of ammonia shortens the time to meet EU regulation concerning reduction of salmonella and enterococci (5 log). Unless a minimum retention time of 2 days, post‐treatment digestion is needed to achieve sufficient sanitation in continuous biogas processes. Significance and Impact of the Study: Running mesophilic biogas processes at high ammonia level produces residue with a high fertilizer value. With some stipulations concerning management parameters, such processes provide a method of bacterial sanitation without preceding pasteurization of the incoming organic waste.     

Appraisal of Phlebotomus argentipes habitat suitability using a remotely sensed index in the kala-azar endemic focus of Bihar,India

Visceral leishmaniasis, or kala-azar, is recognised as a serious emerging public health problem in India. In this study, environmental parameters, such as land surface temperature (LST) and renormalised difference vegetation indices (RDVI), were used to delineate the association between environmental variables and Phlebotomus argentipes abundance in a representative endemic region of Bihar, India. The adult P. argentipes were collected between September 2009-February 2010 using the hand-held aspirator technique. The distribution of P. argentipes was analysed with the LST and RDVI of the peak and lean seasons. The association between environmental covariates and P. argentipes density was analysed a multivariate linear regression model. The sandfly density at its maximum in September, whereas the minimum density was recorded in January. The regression model indicated that the season, minimum LST, mean LST and mean RDVI were the best environmental covariates for the P. argentipes distribution. The final model indicated that nearly 74% of the variance of sandfly density could be explained by these environmental covariates. This approach might be useful for mapping and predicting the distribution of P. argentipes, which may help the health agencies that are involved in the kala-azar control programme focus on high-risk areas.     

近50年北京植被对全球变暖的响应及其时效--基于遥感数据和物候资料的分析

植被对全球变暖的响应方式及其程度问题是全球变化研究的焦点之一。利用1951～2000年的气温、降水等气候资料、1982～2000年的NOAA／AVHRR遥感数据和1951～2002年山桃始花的物候数据,分析了北京各气候参量与生态系统植被在年际和年内时间尺度上的变化规律及其关系。结果表明,北京近20年增温1．2E,增温态势显著;过去50年中,降水的年际变化小于生长季内的波动幅度。年NDVI最大值(VP)、平均值(VM)的年际变化曲线呈波动中缓慢上升的趋势,表明植被的生长状况总体上在变好或生长季在延长。VP出现日期(VPI))提前,20世纪90年代比80年代提前4．5d。山桃始花物候期的分析表明,北京1988年以后春季开始日期提前9．63d。时间尺度不同,各个气候指标对各植被指标的影响程度不同：①年际时间尺度,年均温影响VP、VM的时效为1年;月际水平上,除温度影响VM的时效为2个月外,各气候参量影响VP、VM的时效为1个月。年际尺度上,温度影响山桃始花时效为2年;月际尺度上,2、3、4月份温度影响山桃始花日期。     

Assessing fragmentation and disturbance of west Kenyan rainforests by means of remotely sensed time series data and landscape metrics

Biodiversity in tropical rainforests is heavily influenced by land use/cover change (LUCC), but so far there have been few LUCC studies conducted in Africa. We present several methods that make use of remotely sensed data and landscape metrics and allow for assessment of the development of land cover and thus forest fragmentation and disturbance over a substantial period of time. The study covers Kakamega Forest and its associated forest areas in western Kenya, over the last 30 years. The accuracy of a supervised multispectral classification of Landsat time series data encompassing seven time steps between 1972 and 2001 is numerically assessed using ground truth reference data considering the 2001 time step. Here, buffering the forest areas by 1 km, highest user's accuracies for the forest classes ‘near natural + old secondary forest’ (87.50%), ‘secondary forest’ (80.00%) and ‘bushland/shrubs’ (81.08%) are revealed. Images of a spatially distributed fragmentation index derived from the land cover time series by applying a three by 3 pixel‐sized moving window to determine forest pixels’ adjacency, highlight trends in forest fragmentation, e.g. the splitting into two separate forests along the Yala/Ikuywa corridor. Calculations of mean fragmentation indices for the Biodiversity Monitoring Transect Analysis in Eastern Africa (BIOTA‐East Africa) focus research areas are used to evaluate the fragmentation index and to demonstrate its potential to extrapolate (e.g. biological) field findings in space and time. Here we argue for a correlation of the fragmentation indices results not only with forest management regimes, but with population distribution and accessibility (e.g. by roads). A cluster analysis applying the isodata‐algorithm on the classification results of all seven times steps allows for a rapid visual assessment of the distinct pattern of typical land cover development trends since 1972. This reveals that parts of Kakamega Forest have experienced severe forest loss while others, especially in the north‐east, show signs of succession.     

黑河流域叶面积指数（LAI）空间尺度转换

为有机地整合利用不同分辨率遥感数据获取的陆面过程以及其他相关的环境变量,尺度问题越来越受到人们的重视.选取黑河张掖绿洲区为实验研究区,利用ETM 影像反演的LAI通过升尺度转换到900m分辨率,对LAI尺度转换过程中引起的误差进行了定量分析,尝试提出一种新的基于NDVI像元分解的更有效的升尺度转换方法.研究发现非线性的升尺度算法引起的误差不超过 10.5%,且误差大小与地表异质性程度正相关,而地表异质性是导致LAI尺度转化误差的主要原因,严重时可能造成 45%的偏差,但纯像元LAI的计算不受尺度影响.提出的基于NDVI像元分解的LAI升尺度转换算法,分两步考虑了地表异质性问题,很好的实现了研究区30m空间精度 LAI向900m的尺度转换,该方法应用于干旱、半干旱的中国西北黑河流域NASA 发布的MODIS LAI产品校正,取得了良好效果.     

Spatial scale and sampling size affect the concordance between remotely sensed information and plant community discrimination in restoration monitoring

Remote sensing cartography and GIS are part of ordinary practice in restoration ecology in discriminating patches of habitats, defining objectives, and planning the monitoring phase, but derived information is not always consistent with field survey. We assessed the mapping process efficiency in discriminating different communities, relying on plant composition data, and considering the effect of sample size and plot dimension (grain), in a heterogeneous environment in Tuscany (central Italy). We identified four land cover classes on a land cover map produced with object-oriented technique; hence we conducted a sampling of 64 plots (4 zones × 4 classes × 4 plots), estimating vascular plant cover using a point-quadrant method. Plots were nested squares with side lengths of 0.50 m, 1 m and, limited to a sub-sample, 2 m. We evaluated the effect of sample size and grain using permutational multivariate analysis of variance (PERMANOVA), testing the simultaneous response of species composition compared to land cover classes. Results demonstrated that for a sample size of 64 plots, grain does not influence the ability of discriminating among the habitat types investigated, while for a smaller sub-sample the effect of grain is significant and communities cannot be distinguished at all plot dimensions. Outcomes corroborate the hypothesis that sampling at a series of scales of observations and an adequate sample size can improve monitoring efficiency in restoration ecology. Nomenclature: Pignatti (1982) and Conti et al (2005) for Festuca.     

Phylogenetic and functional diversity of Bacteria and Archaea in a unique stratified lagoon, the Clipperton atoll (N Pacific)

The Clipperton lagoon in the North Pacific Ocean has been isolated from the surrounding sea for c. 160 years. It has a stratified water column that comprises an oxic and brackish upper water layer (mixolimnion) and a deep sulfuric anoxic saline layer (monimolimnion), separated by a steep pycnocline. Here, we test whether the Clipperton lagoon with its distinctive physico-chemical features, geographic isolation, recent water column stratification, and large nutrient input harbors original microbial communities. The combination of capillary electrophoresis single-strand polymorphism (CE-SSCP) fingerprinting and sequencing of cloned bacterial and archaeal 16S rRNA genes, and functional genes for methanogenesis (mcrA), methanotrophy (pmoA), and sulfate reduction (dsrAB), revealed that microbial communities and pathways were highly stratified down the water column. The mixolimnion contained ubiquitous freshwater clades of Alpha- and Betaproteobacteria, while the pycnocline contained mostly green sulfur bacteria (phylum Chlorobi). Sequences of the upper layers were closely related to sequences found in other aquatic ecosystems, suggesting that they have a strong potential for dispersal and colonization. In contrast, the monimolimnion contained new deeply branching bacterial divisions within the OP11 cluster and the Bacteroidetes, and was the most diverse of the layers. The unique environmental conditions characterizing the deep layers of the lagoon may explain the novelty of the microbial communities found at the Clipperton atoll.     

Linking field-based ecological data with remotely sensed data using a geographic information system in two malaria endemic urban areas of Kenya

BACKGROUND: Remote sensing technology provides detailed spectral and thermal images of the earth's surface from which surrogate ecological indicators of complex processes can be measured. METHODS: Remote sensing data were overlaid onto georeferenced entomological and human ecological data randomly sampled during April and May 2001 in the cities of Kisumu (population asymptotically equal to 320,000) and Malindi (population asymptotically equal to 81,000), Kenya. Grid cells of 270 meters x 270 meters were used to generate spatial sampling units for each city for the collection of entomological and human ecological field-based data. Multispectral Thermal Imager (MTI) satellite data in the visible spectrum at five meter resolution were acquired for Kisumu and Malindi during February and March 2001, respectively. The MTI data were fit and aggregated to the 270 meter x 270 meter grid cells used in field-based sampling using a geographic information system. The normalized difference vegetation index (NDVI) was calculated and scaled from MTI data for selected grid cells. Regression analysis was used to assess associations between NDVI values and entomological and human ecological variables at the grid cell level. RESULTS: Multivariate linear regression showed that as household density increased, mean grid cell NDVI decreased (global F-test = 9.81, df 3,72, P-value = <0.01; adjusted R2 = 0.26). Given household density, the number of potential anopheline larval habitats per grid cell also increased with increasing values of mean grid cell NDVI (global F-test = 14.29, df 3,36, P-value = <0.01; adjusted R2 = 0.51). CONCLUSIONS: NDVI values obtained from MTI data were successfully overlaid onto georeferenced entomological and human ecological data spatially sampled at a scale of 270 meters x 270 meters. Results demonstrate that NDVI at such a scale was sufficient to describe variations in entomological and human ecological parameters across both cities.     

Morphological and phenological comparisons of two Hopi maize varieties conserved in situ and ex situ

Over the last twenty-five years, crop genetic resources (CGR) have been preserved in genebanks around the world for use by formal plant breeders. Recently conservation of folk crop varieties for direct use by the farmer-breeders of traditional agricultural communities has been suggested as another purpose for CGR conservation. While both in and ex situ CGR conservation programs have been proposed to meet the needs of formal plant breeders and farming communities, the needs and goals of the two groups are different. Formal breeders seek maximum allelic diversity while farmer-breeders are interested in both diversity and population structure that provide local adaptation. Based on the morphological and phenological data analyzed for this study of two Hopi maize varieties conserved in and ex situ, it appears that both genetic shift and genetic drift have occurred ex situ, and that populations conserved ex situ are different from those maintained in situ. These findings suggest that CGR conservation strategies must be re-evaluated in light of the specific conservation goals that are sought.