A STUDY OF THE CINNAMON-BREASTED ROCK BUNTING Fringillaria tahapisi tehepisi

Brown, C. J. &; Piper, S. E. 1988. Status of Cape Vultures in the Natal Drakensberg and their cliff site selection. Ostrich 59:126-136.

Ground, aerial and questionnaire surveys on the status of the Cape Vulture Gyps coprotheres in the Little and High Drakensberg mountain ranges of Natal were carried out from 1981–1983. The area supported at least 1325 Cape Vultures, 60% on the High Drakensberg in 17 nesting colonies (mean of 31 birds per colony) and 38 roosts (mean of 7 birds). In the Little Drakensberg 17 sites were found, six of which were confirmed nesting colonies (mean of 53 birds) and seven were roosts (mean of 16 birds). A minimum of 215 nests was recorded while the actual number of breeding pairs was probably about 325. In the Natal Drakensberg 84% of nests and 77% of roosting birds occupied ledges that faced between east and south, on the lee side of the generally westerly and northwesterly “Bergwind”. Nesting ledges in the High Drakensberg were on average about 100 m lower than roosting ledges. The northern Drakensberg supported the largest numbers of Cape Vultures (19 birds per 10 km of cliffs), while the smallest numbers were recorded in the south (8 birds per 10 km of cliffs). In the south smallstock farming predominates and the availability of carrion is higher than in the north where mainly largestock are farmed. The use of poisons (mainly strychnine) for killing mammalian predators on farms is considered to be the main reason for fewer birds occurring in the south, and is the main threat to Cape Vultures in the Natal Drakensberg.     

Genetic structure of the common impala (Aepyceros melampus melampus) in South Africa: phylogeography and implications for conservation

We analysed 131 common impala (Aepyceros melampus melampus) samples from two provinces in South Africa (Limpopo and KwaZulu‐Natal) that are separated by the Drakensberg Mountain Range using sequences of the mitochondrial control region and seven polymorphic nuclear microsatellite loci. In line with earlier studies on bovid species, we found very high values of genetic diversity, particularly at the mtDNA locus with an overall nucleotide diversity of 3.6% and an overall haplotype diversity of 0.98. All statistical approaches confirmed a significant population differentiation between Limpopo and KwaZulu‐Natal, suggesting that areas of unsuitable habitat caused by the presence of the Drakensberg Range and the Indian Ocean coastal belt act as a barrier to gene flow. Only few individuals with signs of admixed origin were indicative of translocations or rare migration between the two provinces. Combination of our mtDNA data set with those of previous studies on impala from south‐western, southern and eastern Africa revealed the highest diversity in South Africa. This is in line with the hypothesis of a southern glacial refuge from which various African ungulate species spread northeast during the Holocene, although in the case of impala further analyses based on larger data sets will be necessary to definitively settle this question.     

Abundance estimation of rocky shore invertebrates at small spatial scale by high-resolution digital photography and digital image analysis

We have tested both the usefulness of high-resolution digital photography for data acquisition and digital image analysis, by non-supervised classification and high pass filter, for recognition and abundance estimation of benthic intertidal organisms. These digital tools were compared with visual scan and photo quadrat conventional methods. The comparison was done using 40 quadrats (10×5 cm) randomly selected along a 5-m transect on the rocky shore of the Pemaquid Point, Maine, USA. ANOVA for repeated measures was used to test differences among methods. Monte Carlo simulation analysis was used to explore differences among methods over a large set of data (n=100, 500, 1000 quadrats). Differences among methods were observed when 40 quadrats were used. Tukey multiple comparison test showed that abundance estimation from visual scan, photo quadrat and digital image analysis by high pass filter do not differ significantly among them but differ from non-supervised classification results. Due to its accurate estimation, high pass filter (Prewitt) method was chosen as the most reliable digital method to estimate species abundance. Monte Carlo simulation of visual scan, photo quadrat and high pass filter results showed significant differences when the number of quadrats was larger. These results showed that the combined use of digital photography and digital image analysis techniques for the acquisition and analysis of recorded data is a powerful method for the study of intertidal benthic organisms. Results produced using these techniques were similar than those produced by conventional methods but were obtained in a much-reduced time.     

柱花草种质资源研究进展

柱花草属(Stylosanthes Sw.)约含50个种(包括二倍体和多倍体), 染色体基数x=10, 是热带和亚热带地区的优良豆科牧草, 其中圭亚那柱花草(S. guianensis Sw.)、有钩柱花草(S. hamata (L.) Taub.)、西卡柱花草(S. scabra Vog.)、矮柱花草(S. humilis Kunth)和灌木柱花草(S. seabrana B. L. Maas s & 't Mannetje)的种植面积最广。由于柱花草产量高、营养丰富、栽培容易且用途广泛(可用于青稞饲料、调制干草和干草粉、牧地种植、果树间种、水土保持及绿肥等), 被许多国家用于热带和亚热带农业生产中, 如亚洲的中国、印度、泰国和马来西亚等, 澳洲的澳大利亚, 美洲的美国、哥伦比亚、巴西和古巴, 以及非洲的尼日利亚等。该文对柱花草种质资源的系统学、种质收集、评价、利用及育种等方面的研究进展进行了系统的概括和归纳, 并展望了当前柱花草研究的热点领域和亟待解决的问题。     

Avifauna of two upland evergreen forest reserves,the Atewa range and Tano Offin,in Ghana

Ntiamoa-Baidu, Y., Asamoah, S.A., Owusu, E.H. & Owusu-Boateng, K. 2000. Avifauna of two upland evergreen forest reserves, the Atewa Range and Tan0 Offin, in Ghana. Ostrich 71 (1 & 2): 277–281.

Data are presented on the avifauna of two Upland Evergreen forest reserves in Ghana: Atewa Range Forest Reserve and the Tano Offin Forest Reserve. The data obtained for the two reserves using three survey techniques: transect counts, timed species counts and mist-netting are compared. A total of 105 species were recorded for the Atewa Range Forest Reserve while the Tano-Offin Forest Reserve yielded 110 species. Mean species encounter rate in the transect counts at Atewa was 24.2 per km while individual bird encounter rate was 52.6 per km; encounter rates at Tano Offin were 31.2 per km. and 98.2 per km for species and individual birds respectively. The most common species encountered in Atewa was the Yellow-whiskered Greenbul Andropadus latimstris (7.1% of observations in transect counts and 6.7% in spot counts), while the Green-crested Touraco (6.6% of transect counts) and Green Hylia (5.7% of spot counts) were the most abundant at Tan0 Offin. The records for Atewa included four globally threatened species while Tano yielded three threatened species. Two species of birds, the Equatorial Akalat Sheppardia aequatorialis and the yellow-bellied Greenbul Phyllastrepus flavostn'atus were recorded for the first time in Ghana from the two reserves. The bird community at Tan0 Ofin was significantly more diverse than that at Atewa. In both reserves, spot counts yielded more species (67.6% and 74.5% of total recorded at Atewa and Tan0 respectively), than transect counts and mist nets. 31 species recorded in both spot counts and transect counts at Atewa were not captured in mist nets, while nine species caught in mist nets were not recorded by the two methods. The figures for the Tano Offin reserve were 43 and six respectively. We conclude that of the three survey techniques, the timed species counts offer the most comprehensive results for rapid assessment of forest avifauna, but a combination of all three methods is necessary for complete coverage. The need for management of the two reserves to maintain their unique biodiversity in the face-of threats from mining and logging is discussed.     

Comparing agglomerative clustering and three weed classification frameworks to assess the invasiveness of alien species across spatial scales

To prioritize weed management at the catchment scale, information is required on the species present, their relatively frequency, abundance, and likely spread and impact. The objective of this study was to classify the invasiveness of alien species that have invaded the Upper Burdekin Catchment in Queensland, Australia, at three spatial scales. A combination of three published weed classification frameworks and multivariate techniques were employed to classify species based on their frequency and cover at a range of spatial scales. We surveyed the Upper Burdekin Catchment for alien species, and for each species determined the following distribution indices — site frequency, total cover, transect frequency per site frequency and quadrat frequency per site frequency, cover per quadrat when present, cover per transect when present, and cover per site when present. These indices capture the effect of species abundance and frequency between sites (site frequency and total cover), within sites (transect frequency per site and cover per transect when present), and within transects (quadrat frequency per site frequency and cover per site). They were used to classify the species into seven groups using a hierarchical cluster analysis. The relationship between the indices was explored to determine how effective the small scale, site‐specific indices were at predicting the broader, landscape‐scale patterns. Strong correlations were observed between transect frequency per site and frequency (r² = 0.89) and cover per transect when present and total cover (r² = 0.62). This suggests that if a weed is abundant at the site level, it has the potential to occupy large areas of the catchment. The species groupings derived from the application of the three published weed classification frameworks were compared graphically to the groupings derived from the cluster analysis. One of the frameworks classified species into three groups. The other two frameworks classified species into four groups. There was a high degree of subjectivity in applying the frameworks to the survey data. Some of the data were of no relevance to the classification frameworks and were therefore ignored. We suggest that the weed classification frameworks should be used in conjunction with existing multivariate techniques to ensure that classifications capture important natural variations in observed data that may reflect invasion processes. The combined use of the frameworks and multivariate techniques enabled us to aggregate species into categories appropriate for management.     

东灵山辽东栎林木本植物种间联结取样技术的研究

 在样地面积固定条件下,采用样方设计和样带设计,探讨了样方数目与面积之间的关系,以及样方数目与面积的变化对种间联结的影响。结果表明：正负关联比、平均物种出现率、多物种间X2值、物种对间X2值与显著率以及物种间联结系数的变化范围均可作为确定样方数目与面积的参数。在实际分析中应当综合考虑这些参数,进而选择最佳样方数目及面积进行种间联结分析。在样地总面积均为1 200 m2条件下,样带设计在各项指标上规律性比较明显,样方数为50,面积为25 m2最为合适;样方设计的各项参数稍差一些,需要进一步增加样方总面积才能得到更合适的样方数。分别按选定的最适样方数进行物种对联结性分析,对比分析结果显示样带设计对联结性和关联程度的检测效果好于样方设计,它的研究结果更与实际情况相符合。因此,在总样地面积有限的情况下,样带设计是进行种间联结分析的较好选择。     

New species of Wahlenbergia (Campanulaceae) from Africa

Five new species of Wahlenbergia are described and illustrated: W. tetramera from the high Drakensberg in Natal, W. petraea from Burundi, and W. marunguensis, W. polyphylla and W. malaissei from Zaire.     

Interpretation of scale in paired quadrat variance methods

Question: Previous interpretations of the variance plot of paired quadrat variance method (PQV) have been incomplete. The objective of this study was to clarify the interpretation of PQV, and to shed additional light on how different quadrat variance methods can be used, in concert, to measure scale in transect data. Methods: We used artificial and real data to examine how the PQVmethod elucidates spatial pattern. Two‐term local quadrat variance (TTLQV) and new local variance (NLV) methods, together with their three‐term counterparts, were also applied to the same data sets, and the results from all methods were compared. Results: When the mean gap size equalled the mean patch size along a transect, the first peak of the variance of PQV, NLV and TTLQV corresponded with the gap size (or patch size). However, if the mean gap size and patch size were unequal, the variance plot of PQV displayed a flat‐topped plateau, in which the first inflection represented the mean size of the smaller phase and the second inflection represented the mean size of the larger phase; TTLQV showed a clear peak and NLV displayed a distinct first peak while the second inflection was dampened. The results also indicated than the three‐term versions of quadrat variance methods did not consistently outperform their two‐term counterparts, and often confused the interpretation of scale. Conclusions: The quadrat variance methods associated with the patch‐gap measurements were able to efficiently detect not only the size of patches, but also the size of gaps.     

Field and simulation analyses of visual methods for sampling coral cover

The consensus view that coral reefs are declining urges the need to test the short-term effects of conservation. Visual sampling methods are a low cost, technically simple, and potentially highly accurate means of monitoring reef status or calibrating larger scale aerial and satellite surveys. We studied the recent literature and found that of the three most commonly used visual methods, the belt transect (BT) method was used twice as much as the line transect (LT) method and 2.5 times as often as the linear point intercept (LPI) method. We tested the repeatability, cost-efficiency, precision, and accuracy of these three methods in the field and in computer simulations. In the field, the observer repeatability was uniformly high among the three methods (R>0.9). Surprisingly, our study indicates that the least used method (LPI) was the most cost-effective means of measuring coral cover while being at least as precise and accurate as the other two methods. Our simulation study indicated that both the accuracy and precision of the three methods decrease sharply with decreasing coral cover, and that using between 5 and 10 transects over a homogeneous area is an appropriate sample size at either low or high coral cover.     

Review of the Methods Frequently Used to Estimate the Abundance of Orthoptera in Grassland Ecosystems

Ecologists have quantified Orthoptera (grasshoppers and crickets) density in a wide variety of conservation studies. Objective determination of Orthoptera population size is possible using mark-release recapture techniques but these are time-consuming and of little use for all but the smallest scale studies. Therefore, a wide range of sampling techniques have been devised to quantify population density and the most commonly used methods include sweep netting and quadrat counts. It is the aim of this paper to critically review studies that have used these techniques and to provide useful suggestions for non-specialists on which method may be most applicable to their study site. This paper reviews a selection of the extensive literature reporting studies estimating the abundance of grasshoppers (Acrididae) in a wide range of grassland ecosystems. Where possible, studies on bush-crickets (Tettigoniidae) and crickets (Gryllidae) are included reflecting their overall contribution to assemblage diversity in grassland ecosystems and to highlight the need for further investigations of sampling efficiency on these two under-researched families.The most rapid and inexpensive sampling methods, such as quadrat and transect counts, involve ‘flushing’ grasshoppers from the sward. These techniques are fairly accurate in short, open swards (<50 cm sward height) where grasshopper densities are low (<2 adults per m²). At higher population densities (>2 adults per m²), methods which require the capture of grasshoppers such as box quadrats and sweep netting may be more appropriate. Sampling grasshopper populations in taller vegetation (>50 cm sward height) is more problematic as the efficiency of many techniques may be reduced by vegetation structure. Methods such as timed counts can be used at low densities (<2 adults per m²) and night trapping might be most applicable where high numbers of grasshoppers are present (>2 adults per m²).There is an urgent need for development of a standardised sampling technique that can produce comparable data from studies with a wide variety of observers in grasslands with differing vegetation structures and grasshopper densities.     

雪灾对九华山风景区毛竹林的影响

国内外关于雪灾对生态脆弱区的生态系统组成及功能破坏影响的研究较少, 并且相关研究还主要停留在定性阶段, 定量研究生态脆弱区的雪灾对林木破坏的影响理论和实践意义重大。综合运用样方法和样带法对生态脆弱区——九华山风景区林木受灾情况进行调查, 对不同海拔、坡向、竹龄、群落重要值和距游径不同距离的100个样方和40个样带共计14 000 m²的毛竹(Phyllostachys pubescens)损坏情况进行了量化分析。结果显示毛竹损坏率和其立地条件有以下关系: 阴坡>阳坡; 高海拔>低海拔; 毛竹损坏率和它在群落中的重要值呈正相关, 毛竹纯林>混交林; 损坏毛竹平均胸径为(9.8 ± 1.3) cm, 损坏主要集中在幼龄阶段的毛竹; 距游径4 m内的毛竹损坏程度比4 m外显著(p < 0.05)。根据以上结果, 提出了灾后营林造林的原则和雪灾对森林生态系统影响量化研究的几个重要方向。     

Species density and associations in Caribbean reef corals

The density of scleractinian corals on portions of two reefs in the Grenadine Islands, W. I. has been investigated by direct observation by SCUBA divers. Grid, transect, and random quadrat methods were compared with total samples to determine the precision and accuracy of these techniques. Transect methods were generally satisfactory provided at least 15% of a 400 m² total grid area was included in the sample. The data strongly indicated clumped distributions of all species, although numerical analysis does not indicate the distinct zones reported by other workers. Species associations based on Jaccard's coefficient and cluster analysis showed possible similarities in physical requirements, although few strong associations were found. Data based on 4 m² quadrats generally provided a more reliable estimate of species associations than did data based on 1 m² quadrats. It is suggested that surveys of these reef types may be better based on a number of parallel transects rather than a single transect, and that well-defined zones are more likely to be the exception than the rule.     

北方冬季有蹄类动物4种数量调查方法的比较

科学的种群数量调查方法的探索一直是困扰北方有蹄类动物种群资源有效管理工作的重要问题。目前,北方野生有蹄类调查所采用的方法主要有样线法、样带法、大样方法和非损伤性CMR法4种。然而,不同的调查方法基于的统计学假设和生态学原理不同,调查结果往往会出现很大差异,迫切需要对北方冬季有蹄类动物的这4 种调查方法的有效性进行评估。以驼鹿种群数量调查为例,采用样线法、样带法、大样方法和非损伤性CMR调查法,于2012年3月和2012年12月对内蒙古汗马国家级自然保护区约120 km²的区域驼鹿种群数量进行了调查和评估。 结果显示,以上4 种方法得到的驼鹿种群数量分别为:样线法168(109-227) 只,样带法237(165-309) 只,大样方法37(23-50) 只,非损伤性CMR法55(43-68) 只,表明样线法和样带法的调查结果远大于大样方法和非损伤性CMR法,并探讨了不同调查方法应用的科学性、限制性和适用性,为北方冬季有蹄类动物种群资源调查方法的选择和应用提供了科学参考。     

Plant cover estimation based on the beta distribution in grassland vegetation

Cover is the most frequently used measure of abundance in vegetation surveys of grasslands, and various qualitative and semi-quantitative methods have been developed for visual estimation of this metric. Field survey is usually made with a point-grid plate. The frequency distributions of cover derived from point-grid counts follow a beta distribution. Combining point-grid counts from a field survey and the beta distribution for a statistical analysis, we developed an effort-saving cover-measurement method. Cover is measured with a transparent plastic plate on which, for example, 10 × 10 = 100 points are arranged in a lattice with 1-cm grid spacing (thus, one point count represents 1 cm² of cover). N quadrats are set out at randomly dispersed sites in a grassland, and, in each, the plastic plate is used for making counts. The number of grid points located above a given species is counted in every quadrat until the number of counted points reaches a given value c, which is determined in advance. If the number of counted points reaches c in a quadrat, the count is stopped and the quadrat is classified in the category “>c”. In quadrats where c is not attained, full point counts above the species bodies are made. Let g be the number of observed quadrats whose cover is ≤c. Using these g cover measurements and the number of quadrats (N − g) with cover >c, we can quantitatively estimate cover for each species and the spatial pattern index value based on the maximum likelihood method. In trial counts using this method, the time savings varied between 5% and 41%, depending on the shape of the cover frequency distribution. The mean cover value estimates agreed well with conventional measures without a stopping point (i.e., based on full counts of all points in each quadrat).     

A new species-time method for visual assessment of fishes and its comparison with established methods

Synopsis Relative abundances for 80 species in a fish assemblage were estimated using three visual assessment methods. Results of two species-time methods, the Rapid Visual Census (RVC) of Jones & Thompson (1978) and a new method, the Visual Fast Count (VFC), are compared to the traditional transect method. The VFC is similar to the RVC but it is an attempt to improve: on the quantitative nature of the results. Results from each method were significantly correlated, but important differences between methods were found. With an equal number of replicates both RVC and VFC methods yielded significantly more species than the transect method. Relative abundances estimated by the RVC were significantly different from those determined by either VFC or transect methods, but VFC and transect results were not different. A qualitative similarity index using presence-absence data was calculated and compared among methods. Values ranged from 84.3 to 85.9%, illustrating a consistent level of similarity for the faunas censused regardless of census method. Quantitative similarities (percent similarity), however, ranged from 45.8 to 85.7% and suggest a closer agreement between the transect and the VFC methods than between these methods and the RVC. If transect results are assumed to be the most accurate, the comparison suggests that the VFC method yields more accurate relative abundances than does the RVC. Ranges in percent similarity values calculated within each method (8 replicate samples) were used to compare precision among methods. While transect and RVC scores are slightly more precise (ranges of 3.10% and 2.20% respectively) than the VFC method (range = 4.89%), no method was statistically more precise than another (P<0.001).     

植物群落对景观温度特征指示作用的研究

以德国Kraichgau地区为研究样区,根据转化糖方法获得的野外实测温度数据,就植物群落温度平均指示值在景观尺度上对生境温度的指示效果进行了深入探讨。结果表明：1)群落温度平均指示值与测定的效应温度之间具明显线性正相关;2)群落温度平均指示值能够反映不同坡向条件造成的生境温度差异,但效果随计算方法不同而异。3种不同方法的比较结果说明,直接根据样方资料获得的计算结果,对坡向条件造成的生境温度差异反映明显;3)以样带数据为基础的研究结果对温度随坡向和坡位变化的反映均不够明显。样带没有达到足够的宽度以及样带中局部地段上的种类组成受人为影响严重可能是未达到预期对比效果的主要原因。     

Incoming solar radiation patterns and vegetation response: Examples from the natal drakensberg

Summary A method of accurately estimating and mapping patterns of incoming solar radiation fluxes on sloping terrain, using data from standard meteorological instruments, is described. The results of the radiation maps produced are then related to a specific example of vegetation successional changes in the Cathedral Peak area of the Natal Drakensberg mountain range, indicating that these changes occur most readily on cooler aspects. For the same region, the differences in the major plant communities at two other sites, attributable largely to variations in incoming solar radiation loads, are discussed.The authors wish to thank the Department of Forestry of the Republic of South Africa for providing data and for facilitating fieldwork to be undertaken at Cathedral Peak. This Research was funded in part by the South African Council for Scientific and Industrial Research, whose support is hereby gratefully acknowledged (by R.E.S.). The maps illustrating this paper were prepared by Mrs. C. Coetzee and Mr B. Martin of the University of Natal, Pietermaritzburg.     

Composition and structure of a species rich Amazonian rain forest obtained by two different sample methods

Inventory data for trees ≥ 10 cm DBH from a hectare plot are compared to data obtained by the Point-Centered Quarter Method along a line transect from the same locality in Anangu, Amazonian Ecuador. The one-hectare quadrat plot of 100 × 100 m had 734 individuals, 153 species, 46 families, a total basal area of 22.2 m², and an estimated above ground tree volume of 240.5 m³. The line transect had a calculated density of 728 individuals per hectare, which included 239 species, 51 families, a total basal area of 34.1 m², and an estimated above ground tree volume of 409.6 m³. Of the 20 species with the highest IVI, only four were shared by the two samples. The most important species were Quararibea ochrocalyx on the hectare plot and Iriartea deltoidea on the line transect, constituting 26.6 and 13.3% of the individuals, respectively. The five families with the highest FIV on the hectare plot (Bombacaceae, Arecaceae, Moraceae, Caesalpinaceae, and Lauraceae) and on the line transect (Arecaceae, Moraceae, Meliaceae, Mimosaceae and Caesalpinaceae) constitute 40.4% and 35.4% of the Family Importance Values of the samples, respectively. The Point-Centered Quarter Method used along a line transect reflects maximum diversity and provides average values of density and tree size in the area. The quadrat plot reflects the local structure and composition of the forest within the plot.