浅论沙湾县荒漠生态区荒漠植被的保护与开发利用

沙湾县是以农业生产力支柱产业的地处准噶尔盆地南缘的半干旱荒漠内陆区域,区域内荒漠植物被较脆弱,随着经济与人口的快速增长及农、林、牧业的大发展、如何保护县域内荒漠生态区荒漠植被,更好的开发和利用这种资源、将是一个十分重要的研究课题。     

化学工程固沙在塔里木沙漠公路沙害防治中的适宜性

由于天然材料日益紧缺 ,研制适宜于流动性沙漠地区公路沙害防治的人工替代材料势在必行 .结合塔里木沙漠公路沙害环境 ,实验室优选出 L VA、LVP、WBS和 STB 4种抗性较好的固沙剂 ,对其理化性能、粘结体力学性能和抗风蚀性能等测试结果表明 :颗粒粒径 0.2μm～ 0.5μm,粘度 12 Pa·s～ 15Pa·s;10℃～70℃温度下无沉淀 ,不燃烧 ;实验抗压强度 1.0 MPa～12.1 MPa;10℃～-20℃低温下重量损失率 0%～ 1.8%;紫外光照射 300h强度损失率 0%～ 42%;在 5m·s^-1～253m·s^-1实验风速下 ,风蚀量 0g·(106cm²·h)^-1～4.0 g·(106cm²·h)^-1 ;现场试验固结层厚度 0.2 mm～0.5mm,强度高 .化学工程固沙技术适宜于塔里木沙漠公路沙害防治 .     

土壤酸化及天然土壤溶液中铝的形态

采用真空式土壤溶液采样器收集了宜昌、巫山松树林中天然土壤溶液,采用高效液相色谱法Al－Lumogallion柱后荧光检测,分析测试了土壤溶液中可溶性铝的形态,研究了由于土壤酸化引起天然土壤溶液中不同形态铝的迁移转化结果表明,天然土壤溶液中含有不同形态的铝,主要是有机铝、 AISO₄⁺、AIF₂⁺、Al（OH）²⁺、Al³⁺等．宜昌、巫山地区土壤溶液中活性铝（Al³⁺、AlOH^2+F）的含量比较低．土壤的酸化使得天然土壤溶液中总铝含量增加、铝形态的优势态发生变化,即土壤的酸化使得天然土壤溶液中活性铝－Al³⁺、AlOHF²⁺含量和比例增加．土壤酸化还降低了大然土壤溶液中的BC/Al比值,这些变化的结果都增加了对森林潜在的危害．     

增补UV-B辐射下南亚热带森林建群树种叶片对UV-B辐射的防护

研究了我国南亚热带森林5种建群树种UV-B辐射诱导的UV-B吸收物质(在280～320 nm波长下测定)的积累及抗UV-B辐射的可能性保护机制.增补UV-B辐射下,马尾松(Pinus massoniana)针叶的甲醇可溶性提取物和细胞壁的碱提取酚类的含量明显高于正常水平的光辐射下.红椎(Castanopsis hystrix)和厚壳桂(Cryptocarya chinensis)叶片的这些化学物质也升高,意味着增补UV-B辐射刺激UV-B辐射吸收物质的生成,形成抗UV-B辐射的功能性保护结构.然而,自然光下已含有大量细胞壁碱提取酚类的荷木(Schima superba)和藜蒴(Castanopsis fissa),这些化合物在增补UV-B辐射下则见下降,很有可能表皮层细胞壁碱提取酚类被转移到含有较低甲醇可溶性色素的液胞可溶性化合物里,这一现象意示着可能涉及叶肉组织光合机构的保护策略.增补UV-B下,马尾松针叶的叶绿素a和b含量不受影响,而其他4种阔叶树叶片则下降10.7% 到16.8%不等.胡萝卜素对增补UV-B辐射的响应变化不一,红椎和荷木的胡萝卜素水平下降,而马尾松、厚壳桂和藜蒴的胡萝卜素则上升,后者也许与功能性增加激发能耗散有关.结果显示,自然条件下不同树种展示出不同的驯化策略以形成抗UV-B辐射增加的防护机制.表4参29     

Quantifying Plant Population Persistence in Human-Dominated Landscapes

Abstract:  We assessed population performance of rare plants across a gradient from rural to urban landscapes and evaluated 2 hypotheses central to strategic conservation planning: (1) population performance declines with increasing human dominance and (2) small populations perform poorly relative to larger ones. Assessing these hypotheses is critical to strategic conservation planning. The current conservation paradigm adheres to the well-established ecology theory that small isolated populations, particularly those in human-dominated landscapes, are the least likely to succeed over the long term. Consequently, conservation planning has strongly favored large, remote targets for protection. This shift in conservation toward ecosystem-based programs and protection of populations within large, remote systems has been at the expense of protection of the rarest of the rare species, the dominant paradigm for conservation driven by the endangered species act. Yet, avoiding conservation of small populations appears to be based more on theoretical understanding and expert opinion than empiricism. We used Natural Heritage data from California in an assessment of population performance of rare plants across a landscape with an urban-rural gradient. Population performance did not decrease in urban settings or for populations that were initially small. Our results are consistent with a pattern of few species extinctions within these landscapes over the past several decades. We conclude that these populations within compromised landscapes can contribute to overall biodiversity conservation. We further argue that conservation planning for biodiversity preservation should allocate relatively more resources to protecting urban-associated plant taxa because they may provide conservation benefit beyond simply protecting isolated populations; they may be useful in building social interest in conservation.     

A hierarchical Bayesian non-linear spatio-temporal model for the spread of invasive species with application to the Eurasian Collared-Dove

The spread of invasive species is a long studied subject that garners much interest in the ecological research community. Historically the phenomenon has been approached using a purely deterministic mathematical framework (usually involving differential equations of some form). These methods, while scientifically meaningful, are generally highly simplified and fail to account for uncertainty in the data and process, of which our knowledge could not possibly exist without error. We propose a hierarchical Bayesian model for population spread that accommodates data sources with errors, dependence structures between population dynamics parameters, and takes into account prior scientific understanding via non-linear relationships between model parameters and space-time response variables. We model the process (i.e., the bird population in this case) as a Poisson response with spatially varying diffusion coefficients as well as a logistic population growth term using a common reaction-diffusion equation that realistically mimics the ecological process. We focus the application on the ongoing invasion of the Eurasian Collared-Dove.     

Cost-Effective Suppression and Eradication of Invasive Predators

Abstract: Introduced predators can have pronounced effects on naïve prey species; thus, predator control is often essential for conservation of threatened native species. Complete eradication of the predator, although desirable, may be elusive in budget‐limited situations, whereas predator suppression is more feasible and may still achieve conservation goals. We used a stochastic predator–prey model based on a Lotka‐Volterra system to investigate the cost‐effectiveness of predator control to achieve prey conservation. We compared five control strategies: immediate eradication, removal of a constant number of predators (fixed‐number control), removal of a constant proportion of predators (fixed‐rate control), removal of predators that exceed a predetermined threshold (upper‐trigger harvest), and removal of predators whenever their population falls below a lower predetermined threshold (lower‐trigger harvest). We looked at the performance of these strategies when managers could always remove the full number of predators targeted by each strategy, subject to budget availability. Under this assumption immediate eradication reduced the threat to the prey population the most. We then examined the effect of reduced management success in meeting removal targets, assuming removal is more difficult at low predator densities. In this case there was a pronounced reduction in performance of the immediate eradication, fixed‐number, and lower‐trigger strategies. Although immediate eradication still yielded the highest expected minimum prey population size, upper‐trigger harvest yielded the lowest probability of prey extinction and the greatest return on investment (as measured by improvement in expected minimum population size per amount spent). Upper‐trigger harvest was relatively successful because it operated when predator density was highest, which is when predator removal targets can be more easily met and the effect of predators on the prey is most damaging. This suggests that controlling predators only when they are most abundant is the “best” strategy when financial resources are limited and eradication is unlikely.     

Effects of Detectability on Estimates of Geographic Range Size in Bignonieae

Abstract: Extinction risk has not been evaluated for 96% of all described plant species. Given that the Global Strategy for Plant Conservation proposes preliminary conservation assessments of all described plant species by 2010, herbarium specimens (i.e., primary occurrence data) are increasingly being used to infer threat components from estimates of geographic range size. Nevertheless, estimates of range size based on herbarium data may be inaccurate due to collection bias associated with interspecific variation in detectability. We used data on 377 species of Bignonieae to test the hypothesis that there is a positive relationship between detectability and estimates of geographic range size derived from herbarium specimens. This relationship is expected if the proportion of the true geographic range size of a species that is documented by herbarium specimens is given by the product of the true geographic range size and the detectability of the species, assuming no relationship between true geographic range size and detectability. We developed 4 measures of detectability that can be estimated from herbarium data and examined the relationship between detectability and 2 types of estimates of geographic range size: area of occupancy and extent of occurrence. Our results from regressing estimates of extent of occurrence and area of occupancy on detectability across genera provided no support for this hypothesis. The same was true for regressions of estimated extent of occurrence on detectability across species within genera. Nevertheless, regressions of estimated area of occupancy on detectability across species within genera provided partial support for our hypothesis. We considered 3 possible explanations for this mixed outcome: violation of the assumption of no relationship between true geographic range size and detectability; the relationships between estimated geographic range size and detectability may be an artifact of a negative relationship between estimated area of occupancy and the sampling variance of detectability; detectability may have had 2 opposite effects on estimated species range sizes: one determines the proportion of the true range of a species documented by herbarium specimens and the other determines the distribution of true range size for the species actually observed with herbarium data. Our findings should help improve understanding of the potential biases incurred with the use of herbarium data.     

威海市区黑松林群落的物种多样性特征

用3个丰富度指数、2个多样性指数和3个均匀度指数对威海市区11个黑松林群落多样性进行研究,并用相关分析研究了这些指数间的关系,结果表明:(1)黑松混交林群落的丰富度和多样性均高于黑松纯林群落,但均匀度却无此规律;(2)生境最优的黑松+刺槐+麻栎林(位于仙姑顶的样地11)在11个样地中的物种多样性表现最好,丰富度、多样性和均匀度都最大.而生境最差的位于火炬大厦的黑松纯林(样地2)群落的丰富度和多样性指数都最小;(3)除样地2外,其余样地群落的草本层丰富度和多样性都最大,灌木层次之,乔木层最小,均匀度无此规律;(4)3个丰富度指数之间、2个多样性指数之间以及两个Pielou均匀度指数之间存在极显著的相关性,但Alatalo均匀度指数和其它7个指数之间相关性都不显著,同时对8个物种多样性指数进行比较后发现丰富度指数中Patrick指数(S)最优,而多样性指数中Shannon-Wiener(H)最优,均匀度指数中以H为基础计算出的Pielou(JH)指数最优.