Delineating generalized species boundaries from species distribution data and a species distribution model

Species distribution models (SDM) are commonly used to provide information about species ranges or extents, and often are intended to represent the entire area of potential occupancy or suitable habitat in which individuals occur. While SDMs can provide results over various geographic extents, they normally operate within a grid and cannot delimit distinct, smooth boundaries. Additionally, there are instances where a zone of primary occupancy (i.e., a mostly continuous region where species exists, excluding outliers) is better suited for particular analyses, such as when examining source/sink population dynamics or modeling movement into new habitats. We present a semi-automated method to delineate a generalized species boundary (GSB) from SDM output, which provides a practical alternative to digitizing. This preliminary boundary is then manually updated based on inventory data and historical ranges. We used the method to generate contemporary boundaries for 132 tree species of the eastern United States, which are complementary to the ranges generated by Elbert Little for North America during the 1970s, but are not replacements. The methods we present can broadly be applied to other grid-based SDM to generate GSBs.     

Evaluating channel response to an extreme sedimentation event in the context of historical range of variability: Upper Colorado River,USA

In May 2003, a breach in a large irrigation ditch within Rocky Mountain National Park (RMNP) initiated a debris flow that entered Lulu Creek and the Colorado River, where 36 000 m³ of sediment substantially altered channel forms and processes. We present a proof of concept to understand whether the 2003 disturbance is within the historical range of variability (HRV), and whether the recovery potential of the system is sufficient to adapt to the disturbance. Flow and sediment regimes, and channel morphology and stability were monitored on Lulu Creek and the Colorado River from 2004 to 2011. Dominant channel response following the debris flow within Lulu Creek included step development, bed armoring, and channel widening. Step height‐to‐length ratios (H/L) for three reaches on Lulu Creek are outside the HRV of reference channels, with one reach approaching reference conditions. Erosion of approximately 23% of the debris fan volume occurred as a result of the long duration 2011 peak flow. Sediment within the Lulu Creek fan will persist for ~30–190 years, assuming current maximum and mean removal rates. Planform changes on the Colorado River since the debris flow include an increase in single‐thread geometries, with braided reaches where bar deposition occurred. Bedload transport and grain‐size analysis of bedload indicate translational spreading of a sand wave front with a dispersive component in steeper reaches. Lulu Creek is returning to a condition of natural variability, but the Colorado River is outside the HRV expected for steep‐gradient, pool‐riffle channels. Applying HRV to a situation where management questions require a longer term perspective, and pre‐disturbance baseline data are limited, is a useful approach. The HRV analysis facilitates a better understanding of site variability and delineates the range of possibilities of channel form and process to achieve management goals. Copyright © 2012 John Wiley & Sons, Ltd.     

青州国家地质公园规划编制探讨

＂国家地质公园规划＂是国家地质公园的＂宪法＂,是建设和管理国家地质公园的依据。按照国土资源部的要求,获得资格的地质公园必须按照《国家地质公园规划编制技术要求》编制国家地质公园规划,经省级国土资源部门初审后报部审查。青州国家地质公园规划是山东省第一个通过国土资源部审查批准的国家级地质公园规划,本文详细介绍了青州国家地质公园规划编写的要点和心得,以期与各位同行交流和探讨。     

地理国情普查 DOM 的制作及检查

DOM是国情普查内容的重要组成部分,是地理国情普查中调查的重要数据源。本文通过卫星影象纠正,控制点选取,全色波段影像正射纠正,多光谱影像与全色波段影像配准,多光谱影像与全色波段影像融合等技术手段,确保了DOM的精度,为国情普查的后续工作提供精确的基础资料。     

Terrestrial and Submerged Aquatic Vegetation Mapping in Fire Island National Seashore Using High Spatial Resolution Remote Sensing Data

The vegetation communities and spatial patterns on the Fire Island National Seashore are dynamic as the result of interactions with driving forces such as sand deposition, storm-driven over wash, salt spray, surface water, as well as with human disturbances. We used high spatial resolution QuickBird-2 satellite remote sensing data to map both terrestrial and submerged aquatic vegetation communities of the National Seashore. We adopted a stratified classification and unsupervised classification approach for mapping terrestrial vegetation types. Our classification scheme included detailed terrestrial vegetation types identified by previous vegetation mapping efforts of the National Park Service and three generalized categories of high-density seagrass, low-density seagrass coverages, and unvegetated bottom to map the submerged aquatic vegetation habitats. We used underwater videography, GPS-guided field reference photography, and bathymetric data to support remote sensing image classification and information extraction. This study achieved approximately 82% and 75% overall classification accuracy for the terrestrial and submnerged aquatic vegetations, respectively, and provided an updated vegetation inventory and change analysis for the Northeast Coastal and Barrier Network of the National Park Service.     

Long-term trends in the recreational shore-fishery for elf Pomatomus saltatrix (Pomatomidae) along the KwaZulu-Natal coast,South Africa

Elf Pomatomus saltatrix account for between 28% and 80% of the annually recorded recreational shore-angling catch in KwaZulu-Natal, South Africa, and have been subjected to various management regimes over the past 33 years. Management of the elf fishery was amended in 2005 to reduce fishing mortality and enhance egg production, following an assessment in 1997, which considered the elf stock to be overexploited and in need of rebuilding. A compromise was reached whereby the bag limit was reduced from five to four elf per angler per day, but the closed season was shortened, allowing an extra month of fishing for elf. A total of 33 years of recreational elf catches recorded on the National Marine Linefish System was investigated for any long-term trends and how they related to management of this species. Over 3 million angler-outings from the recreational shore-fishery in KZN were analysed, including more than 1.5 million elf in the catch. Despite the fast growth of elf and the latest management intervention seven years ago, which was based on a rigorous investigation of life-history parameters, the present study showed no evidence of an improvement in catch rate. It could not be determined whether this was due to a reduction in the bag limit, which would naturally reduce catch rates or whether other factors, including the shortened closed season, had been detrimental to elf stocks. Some shortfalls in the management of elf are discussed and possible reasons for the great variability in catches, which complicated the assessment of trends, are explored.     

Cosmogenic isotope (Cl) surface exposure dating of the Norber erratics, Yorkshire Dales: Further constraints on the timing of the LGM deglaciation in Britain

Cosmogenic isotope (³⁶Cl) surface exposure dating of four of the erratic boulders at Norber in the Yorkshire Dales National Park, northwest England, yielded mean ages of ∼22.2 ± 2.0 ka BP and ∼18.0 ± 1.6 ka BP for their emplacement. These two mean values derive from different ³⁶Cl production rates used for exposure age calculation. The ages are uncorrected for temporal variations in production rates and may underestimate the true ages by 5-7%. The former age, although implying early deglaciation for this area of the British ice sheet, is not incompatible with minimum deglaciation ages from other contexts and locations in northwest England. However, the latter age is more consistent with the same minimum deglaciation ages and geochronological evidence for ice-free conditions in parts of the northern sector of the Irish Sea. Within uncertainties, the younger of the mean ages from Norber may indicate that boulder emplacement was associated with North Atlantic Heinrich event 1. The limited spatial (downvalley) extent of the Norber boulders implies that at the time of their deposition the ice margin was coincident with the distal margin of the erratic train. Loss of ice cover at Norber was followed by persistent stadial conditions until the abrupt opening of the Lateglacial Interstadial when large carnivorous mammals colonised the area. The ³⁶Cl ages are between ∼3.0 ka and ∼13.0 ka older than previous estimates based on rates of limestone dissolution derived from the heights of pedestals beneath the erratics.     

Anthropogenic hillslope terraces and swidden agriculture in Jiuzhaigou National Park, northern Sichuan, China

Small, irregular terraces on hillslopes, or terracettes, are common landscape features throughout west central China. Despite their prevalence, there is limited understanding of the nature of these topographic features, the processes that form them, and the role humans played in their formation. We used an interdisciplinary approach to investigate the geology, ecology, and cultural history of terracette development within Jiuzhaigou National Park, Sichuan Province, China. Terracettes occur on south facing, 20° slopes at 2500 m elevation, which appears to coincide with places people historically preferred to build villages. Ethnographic interviews suggest that traditional swidden agricultural cycles removed tree roots, causing the loess sediments to lose cohesion, slump, and the terrace risers to retreat uphill over time. This evidence is supported by landslide debris at terracette faces. Archaeological analysis of terracette sites reveal remains of rammed spread soil structures, bones, stone tools, and ceramics dating from at least 2200 years before present within a distinct paleosol layer. Radiocarbon and optically stimulated luminescence dating of terracette sediments ranged in age from between 1500 and 2000 ¹⁴C yr BP and between 16 and 0.30 ka, respectively. These multiple lines of evidence indicate a long history of human habitation within Jiuzhaigou National Park and, taken together, suggest strong links between terracette formation and human-landuse interactions.     

福建沿岸当地平均海面的高程研究与应用

通过对福建沿岸多年来已有的当地平均海面高程资料和与1985国家高程基准的水准点联测成果,分析并研究了福建沿岸主要验潮站的当地平均海面的高程情况和变化趋势,对福建沿岸当地平均海面的高程（1985国家高程基准）进行了比较深入的研究和探讨,阐述了福建沿岸与浙江、广东沿海平均海面高程的连续性和与我国海区平均海面高程的一致性,论述了当地平均海面高程的应用方法,以解决福建沿海海岸地形图和水深图的基准统一及高度衔接问题。     

降水量对连古城自然保护区荒漠植被凋落物分解和氮状态的影响

对连古城自然保护区不同降雨梯度(不截留和分别截留30％、50％、80％)下荒漠典型植被土壤无机氮和原位净氮矿化的凋落物分解和养分释放进行了连续的观测分析.结果表明:(1)随着水分输入减少,凋落物的分解速率减小,凋落物分解速率与年降水量正相关.与此相反,净氮矿化与降水量无关.(2)土壤NO3-浓度随着降水输入的增加而显著...