植物地境及物种地境稳定层

植物地境是其生境的重要组成部分.地境结构的系统分析应作为探索植物与其地境生态关系的重要手段之一.植物地境具有鲜明的耗散结构特征, 内部的宏观稳定性和层次性是适应外界环境的自组织结果, 并与植物根群的“层片”结构相契合.每一“层片”代表一个特定的地下小环境.若地境具有多个“层片”, 说明该地境拥有可被多种植物利用的多样小环境.根群作为根系的主功能区, 是联系植物与地境的纽带.与植物的根系相比, 根群的“层片”现象更清晰.通过根群的“层片”, 不同植物实现资源分割, 避免过激竞争, 能够长期共存.基于地境耗散结构特征分析和各物种根群所处深度范围的统计结果, 首次建立了物种地境稳定层的概念.某一物种根群所处的位置即为该物种的地境稳定层.物种地境稳定层可作为地境生态功能分层的基本单位.较之地境全剖面各指标的平均值, 地境稳定层内理化指标组态更为真实地反映了植物生存的地下环境, 可用以确定物种的生存域; 不同植物的生理和生活习性是对其稳定层内指标组态量值及动态变化规律的一种响应; 地境所能提供的稳定层的多寡及组态对地表植物群落的结构具有一定的控制作用; 地境稳定层的消失和产生, 可导致对应物种的消亡和入侵, 造成植物群落的演替.      

Physical and Human Factors Influencing Potential Fish Habitat Distribution along a Mountain River, France

Potential fish habitat along the Drôme River, France, is a function of the distribution of large woody debris, boulders, undercut banks, gravel substrate, and pools. The distribution of these features is, in turn, a function of channel geomorphology, watershed and riparian forest characteristics. We conducted field work and analysed aerial photographs for 190 elementary segments of 500 m length along the Drôme River's 95 km course from the Alps westward to its confluence with the Rhône River near Loriol. The Drôme River does not follow the classic pattern of a monotone downstream decrease in gradient and change in channel characteristics. Although channel gradient, braided index and channel incision all decrease downstream, stream power is independent of longitudinal distance. These variables are largely controlled by geomorphic, human or hydrologic factors at the reach scale. Potential fish habitat richness decreases downstream, but individual habitat variables affecting habitat richness do not necessarily decrease downstream, many being controlled by local factors rather than by position along the continuum. Large woody debris is more abundant in braided reaches located directly downstream of confluences with main tributaries or downstream input sites. Boulders are most abundant downstream of failed bank protection works or in gorges. To improve fish habitat in the Drôme River, we recommend taking a long-term and large-scale perspective. Because structures placed in this unstable channel are likely to be washed downstream, we propose to emulate natural river dynamics and to permit large woody debris to enter the channel in unstable reaches via bank erosion, and that this debris not be removed (as is routinely done now) but permitted to migrate downstream through the system, creating fish habitat en route.     

内陆水体好氧甲烷氧化过程研究进展

内陆水体是全球碳循环的关键组成部分,是大气中甲烷(CH4)的重要来源,每年从内陆淡水与自然湿地排放进入大气的CH4约为185～357 Tg/a.通常,内陆水体中CH4主要由分布于水层底部的厌氧区或沉积层内的产甲烷菌介导产生,其向水层表面传输的过程中易被甲烷氧化菌所氧化.甲烷氧化菌可分为好氧甲烷氧化菌和厌氧甲烷氧化菌,有...     

呼和浩特市生境质量对城市用地扩展的时空响应

以呼和浩特市为研究区,采用梯度分析法,结合InVEST模型,在评价研究区近27 a城市用地扩展及生境质量演变的基础上,运用双变量空间自相关剖析生境质量对城市用地扩展的时空响应。结果表明：（1） 研究时段内,城市扩展表现为核心区的低密度扩张及外围区的多点扩散,紧凑度不断下降,城市结构不稳定,扩展模式不尽合理。（2） 生境平均值从0.49下降到0.44,质量等级跌至较差水平。低等级生境主要呈圈层向南部、东南部扩散,与建设用地扩展方向基本一致。（3） 建设用地扩展强度与生境质量变化空间分布呈负相关关系,核心外围区的建设用地扩展始终为变化最强烈的地带,生境质量退化也最为剧烈。（4） 斑块密度不断上升,特别是建设用地斑块的增加使得城市景观格局愈发破碎。     

旅游地传统饮食文化原真性感知对满意度与行为意向的影响——以宏村臭鳜鱼为例

在区分地方饮食与传统饮食概念的基础上,选择宏村传统饮食臭鳜鱼作为研究对象,通过对就餐环境、服务、食物3个原真性维度和满意度与行为意向2个维度,构建Amos结构方程模型,探究游客对传统饮食文化的原真性感知及其对旅游地就餐满意度和行为意向的影响。结果显示,3个维度的原真性均对满意度呈显著、直接、正向影响,对行为意向呈显著、间接、正向影响;其中,环境原真性对就餐满意度影响最大,其次为服务原真性,最后为食物原真性。研究认为,即使体验对象是与原真性关联紧密的传统饮食,大众游客仍更关注整体就餐环境和服务氛围,食物本身对满意度的影响最低。游客需求引发传统饮食文化舞台化重塑,并呈现“去传统化”与“去地方化”特征,旅游地饮食文化塑造对环境的关注大于食物,但当地居民更加关注食物本身的口味,主客关注差异和食物生产过程的游客需求导向引发当地居民对舞台化饮食的认同度降低。未来旅游地要充分考虑传统饮食的特殊性,重塑让游客与本地居民更加满意的饮食文化。     

地形位指数模型改进及其在植被覆盖评价中的应用

地形作为影响植被覆盖的重要因素,对植被恢复评价以及生态修复规划意义重大。地形位作为测度地形因子综合效应的指标,具有单一地形因子难以比拟的优势。然而,现有地形位指数算法以整个研究区为参照,未考虑空间异质性,难以反映植被生长的局部环境特征。基于地理学第三定律对地理环境相似的强调,融合“空间位置邻近”和“环境特征相似”,对传统地形位模型进行改进：(1)引入局部窗口算法,以突出局部地形特征;(2)在不同生境因子组合下测算地形位指数,以排除环境差异对地形位作用的干扰。案例研究表明,新模型有效提升了地形位指数对植被覆盖水平的解释力度;当考虑生境因子组合,且采用最优窗口时,局部窗口地形位指数与植被覆盖度之间的相关性最高。此外,通过观察不同生境组合下的地形位指数发现,在高热少水阴坡和高热少水阳坡条件下,植被覆盖度与局部窗口地形位指数具有更高相关性;可见,越是水资源相对匮乏区域,植被覆盖对局部窗口地形位的响应越敏感。本文有望为植被恢复评价与规划提供新的指标。     

High spatial resolution hyperspectral mapping of in-stream habitats, depths, and woody debris in mountain streams

This article evaluates the potential of 1-m resolution, 128-band hyperspectral imagery for mapping in-stream habitats, depths, and woody debris in third- to fifth-order streams in the northern Yellowstone region. Maximum likelihood supervised classification using principal component images provided overall classification accuracies for in-stream habitats (glides, riffles, pools, and eddy drop zones) ranging from 69% for third-order streams to 86% for fifth-order streams. This scale dependency of classification accuracy was probably driven by the greater proportion of transitional boundary areas in the smaller streams. Multiple regressions of measured depths (y) versus principal component scores (x₁, x₂,…, x_n) generated R² values ranging from 67% for high-gradient riffles to 99% for glides in a fifth-order reach. R² values were lower in third-order reaches, ranging from 28% for runs and glides to 94% for pools. The less accurate depth estimates obtained for smaller streams probably resulted from the relative increase in the number of mixed pixels, where a wide range of depths and surface turbulence occurred within a single pixel. Matched filter (MF) mapping of woody debris generated overall accuracies of 83% in the fifth-order Lamar River. Accuracy figures for the in-stream habitat and wood mapping may have been misleadingly low because the fine-resolution imagery captured fine-scale variations not mapped by field teams, which in turn generated false “misclassifications” when the image and field maps were compared.The use of high spatial resolution hyperspectral (HSRH) imagery for stream mapping is limited by the need for clear water to measure depth, by any tree cover obscuring the stream, and by the limited availability of airborne hyperspectral sensors. Nonetheless, the high accuracies achieved in northern Yellowstone streams indicate that HSRH imagery can be a powerful tool for watershed-wide mapping, monitoring, and modeling of streams.     

气候变化对喜马拉雅中部甘达基河流域濒危物种的影响预测（英文）

甘达基河流域位于喜马拉雅山脉中部,是众多濒危野生物种的重要栖息地。然而气候变化使该流域的生态环境变得愈发脆弱。本研究利用最大熵物种分布模型(Max Ent)评估气候变化对喜马拉雅黑熊(Ursus thibetanus laniger)和印度花豹(Panthera pardus fusca)等濒危物种空间分布变化的潜在影响。研究基于物种出没地点、生物气候和地形(海拔、坡度和坡向)等数据拟合模拟并预测物种在目前与未来的潜在分布情况。研究结果显示,目前喜马拉雅黑熊的高度适宜区面积约为1642 km²,占流域面积的5.01%,预计至2050年,其高度适宜区面积在甘达基河流域内将会增加约51 km²;印度花豹的高度适宜区面积约为3999 km²,占流域面积的12.19%,预计至2050年可能会增加到4806 km²。喜马拉雅黑熊的栖息地面积可能会在研究区域的东部(伯塞里、塔托潘尼和班塞以北)增加,而在东部(颂当、切坎帕)、西部(布尔提邦和波邦)和北部(桑波切、玛南、切坎帕)减少;印度花豹的栖息地面积则将在研究...     

Prediction of the consumption rates for juvenile Atlantic salmon (Salmo salar L.) on the scale of habitat patches: Development of empirical models based on stomach contents

Rivers and streams are unstable environments in which estimation of energetic costs and benefits of habitat utilization are the daunting exercise. Empirical models of food consumption may be used to estimate energetic benefits based on abiotic and biotic conditions in patches of habitat. We performed thirty daily surveys of fish stomach contents to estimate the consumption rates for juvenile Atlantic salmon (Salmo salar) in a river. The data were used to assess whether variations of daily consumption rates existed within the river, and to develop empirical models that could predict fish consumption rates using abiotic and biotic conditions as independent variables. Daily consumption rates based on stomach content surveys in the field (range: 0.15–1.49 g dry/(100 g wet day)) varied significantly depending on habitat patch (500–1000 m²), summer period, and sampling year. Variables such as water temperature, numerical density of salmon, water depth and moon phase explained 83–93% of the variations in daily food consumption rates. Daily consumption rates tended to increase with water temperature and depth, and were also higher near a full moon. However, they tended to decrease with the numerical density of salmon. Our work suggests that empirical models based on independent variables that are relatively simple to estimate in the field may be developed to predict fish consumption rates in different habitat patches in a river.