Short-term response of the herbaceous layer within leave patches after harvest

Leave patches, uncut areas in a harvested forest, may conserve herbaceous layer species that decline after forest clearcutting. They may also serve to maintain source populations for the recolonization of the harvest area. The main objective of this study is to characterize the short-term response of the herbaceous layer to clearcut harvesting disturbance within and adjacent to leave patches. Four experimental 1 ha patches and two uncut references were established. Within each patch or reference, belts of five 1 m² quadrats were placed at 50 m and 5 m outside the patch, at 0 m (edge), and at 25 m, 35 m, and 50 m (centre) inside. These belts of quadrats were replicated at all four aspects (North, South, East, and West). Ground vegetation was sampled yearly for 1 year before harvest and 3 years after harvest in the experimental patches and for 2 consecutive years in the references. Some common residual species declined significantly in the clearcuts, but remained stable inside the patches in the short term (3 years after harvest). Overall species composition changed little in the patch interior and edge after harvest. Colonizing species (those that appeared in quadrats after harvest) in the patch exterior were predominantly early-seral species, whereas colonizers in the patch interior tended to be shade-tolerant forest species. Species were grouped a priori based on two habitat preferences (amounts of canopy cover and disturbed substrate). Species characteristic of a habitat with closed canopy and undisturbed substrates that decreased significantly over time in the patch exterior were negatively correlated with the amount of exposed mineral soil and open canopy. Species characteristic of a habitat with open canopy and disturbed substrates that increased significantly at the patch exterior showed a positive correlation with the amount of exposed mineral soil and open canopy. No species’ habitat preference groups declined significantly in the patch interior or edge over time. Based on species’ responses to forest operations, it appears that at least the common forest species are maintained in the short term within leave patches.     

Biodiversity management approaches for stream–riparian areas: Perspectives for Pacific Northwest headwater forests,microclimates, and amphibians

Stream–riparian areas represent a nexus of biodiversity, with disproportionate numbers of species tied to and interacting within this key habitat. New research in Pacific Northwest headwater forests, especially the characterization of microclimates and amphibian distributions, is expanding our perspective of riparian zones, and suggests the need for alternative designs to manage stream–riparian zones and their adjacent uplands. High biodiversity in riparian areas can be attributed to cool moist conditions, high productivity and complex habitat. All 47 northwestern amphibian species have stream–riparian associations, with a third being obligate forms to general stream–riparian areas, and a quarter with life histories reliant on headwater landscapes in particular. Recent recognition that stream-breeding amphibians can disperse hundreds of meters into uplands implies that connectivity among neighboring drainages may be important to their population structures and dynamics. Microclimate studies substantiate a “stream effect” of cool moist conditions permeating upslope into warmer, drier forests. We review forest management approaches relative to headwater riparian areas in the U.S. Pacific Northwest, and we propose scenarios designed to retain all habitats used by amphibians with complex life histories. These include a mix of riparian and upslope management approaches to address the breeding, foraging, overwintering, and dispersal functions of these animals. We speculate that the stream microclimate effect can partly counterbalance edge effects imposed by upslope forest disturbances, hence appropriately sized and managed riparian buffers can protect suitable microclimates at streams and within riparian forests. We propose one approach that focuses habitat conservation in headwater areas – where present management allows extensive logging – on sensitive target species, such as tailed frogs and torrent salamanders that often occur patchily. Assuming both high patchiness and some concordance among the distribution of sensitive species, protecting areas with higher abundances of these animals could justify less protection of currently unoccupied or low-density habitats, where more intensive forest management for timber production could occur. Also, we outline an approach that protects juxtaposed headwater patches, retaining connectivity among sub-drainages using a 6th-field watershed spatial scale for assuring well-distributed protected areas across forested landscapes. However, research is needed to test this approach and to determine whether it is sufficient to buffer downstream water quality and habitat from impacts of headwater management. Offering too-sparse protection everywhere is likely insufficient to conserve headwater habitats and biodiversity, while our alternative targeted protection of selected headwaters does not bind the entire forest landscape into a biodiversity reserve.     

膜片钳技术及其应用

膜片钳技术是在电压钳基础上发展的，将尖端为1μm的玻璃微电极吸附到细胞表面，使微电极与细胞膜形成高阻封接，从而可记录到膜上pA级的离子通道电流，目前已发展了多种记录模式，对细胞进行电压和电流钳制，以观察各种离子通道及其调控。此外膜片钳技术与胞内纤维荧光测钙技术、膜电容监测技术、碳纤维电极局部电化学微量检测技术、逆转录多聚酶链式反应技术（PCR）结合，在药理学、病理学、神经科学、脑科学、细胞生物学和分子生物学等生物科学方面，得到越来越广泛的应用。     

植被斑块格局对砒砂岩坡面土壤侵蚀强度的影响

选取水力侵蚀极其剧烈的砒砂岩区为研究对象,基于野外径流小区的连续监测试验,采用三维激光扫描、无人机航拍与方差均值比率法相结合,对比分析砒砂岩坡面3种典型自然植被格局(聚集分布、均匀分布、随机分布)下的产流产沙特征与坡面微地形的演变规律。结果表明:(1)均匀分布格局对减缓水力侵蚀条件下砒砂岩坡面土壤侵蚀强度的效果最明显,与裸坡相比,减流率达到64%,减沙率达到72%,土壤流失量最少,为0.05 kg/m²。径流泥沙量之间存在多项式曲线关系,拟合函数为y=-0.0462X²+0.5355X-0.865,R²=0.736。(2)均匀分布格局的侵蚀区面积最小,为12.28 m²;沉积区面积最大,为3.44 m²,土壤侵蚀强度较其他坡面弱,以轻度侵蚀为主。(3)均匀分布格局的径流泥沙量与平均沉积深度之间的相关性较强,与径流量呈显著正相关(p＜0.05),相关系数为0.603;与泥沙量呈极显著正相关(p＜0.01),相关系数为0.771。     

空间视域分析方法在八达岭长城风景林分类配置中的应用

以八达岭长城沿线风景林为研究对象, 利用空间视域分析技术, 在ERDAS virtualGIS平台上, 将八达岭长城风景林和游客同时置身于一个虚拟的三维空间中, 通过调整游客在长城上的观测高度和视程, 将长城沿线风景林划分为视觉盲区、视觉感知区、视觉敏感区3个类型, 结合研究区植被、森林起源等专题图数据, 采用空间叠置分析法, 获得新的区划斑块, 从视觉感知方面客观确定每个风景林景斑类型, 为八达岭长城风景林科学经营提供科学依据。结果表明, 八达岭长城风景林区在最远2 000 m视域范围内, 视觉盲区、视觉感知区、视觉敏感区面积824.44 hm²、880.4 hm²、3 247.77 hm²。空间叠加分析将八达岭长城风景林区分为119个风景林景斑类型, 为了经营管理方便, 划分10种大的类型, 分别是视觉敏感区保安灌木林、视觉敏感区保安林、视觉感知区保安林、视觉感知区保安灌木林、视觉盲区保安林、视觉敏感区观光林、视觉感知区观光林、视觉盲区观光林、视觉敏感区游憩林、视觉感知区游憩林。     

Analysis on pedodiversity and spatial subset representativity—the German soil map 1:1,000,000

Knowledge about spatial soil variation in terms of measured pedodiversity, as well as the spatial distribution of soils in terms of spatial subset representativity, offers the possibility to estimate the quality and variance within a soil map. Additionally, it can help to identify representative sample locations. Demonstrated at the German soil map at a scale of 1:1,000,000, this study describes a methodology to analyze the distribution of taxonomical pedodiversity using the Simpson index and a new approach to derive representative spatial subsets based on a modified χ²‐test (χ_m²), which can be used as monitoring areas. To analyze the spatial composition of the soil map and to detect differences in the underlying mapping schemes of the German soil map 1:1,000,000, three different spatial data structures were studied: (1) the entire soil map, (2) the soil map segmented into geomorphological regions, and (3) the soil map segmented into the Federal States of Germany. Representative patches of varying sizes were statistically derived for all spatial subsets as well as the entire soil map ranging from 20 km × 20 km up to 70 km × 70 km. The results show that the measured pedodiversity is linked to both the geomorphology as well as the political borders of the Federal States. On the one hand, this reveals the uncertainty of measuring pedodiversity on the basis of soil‐class maps as the spatial representation of pedodiversity is influenced by the different mapping traditions and methods applied in the 16 Federal States of Germany. On the other hand, it allows the analysis of the aggregation schemes of different landscapes. The presented approach helps to understand large soilscapes and to compare different soil maps of different states and countries as well as to enhance the soil map with additional information. Furthermore, the representative patches can be used to select soil‐monitoring areas.     

乡镇规划调控下的农村居民点空间布局优化

为科学确定农村居民点空间布局优化类型,有效指导农村居民点空间布局优化及新农村建设实践。该文以武川县可可以力更镇为例,在乡镇规划调控的前提下,按农村居民点不同演化方向,将位于城镇建设用地扩展边界范围内的农村居民点确定为城镇化型,位于扩展边界范围外的农村居民点确定为非城镇化型。针对城镇化型农村居民点,因其未来演化方向而将其空间布局优化类型确定为社区化管理型;针对非城镇化型农村居民点,从乡镇总规协调度、生产生活便利度、居民点活跃度3大方面构建农村居民点斑块综合影响力评价指标体系,评价其综合影响力,并据此将其空间布局优化类型划分为综合发展潜力型、原地整治保持型、迁村并点扶持型3类。结果表明,可可以力更镇确定为社区化管理型的农村居民点6个,面积15.29 hm2;综合发展潜力型46个,面积178.28 hm2;原地整治保持型53个,面积189.20 hm2;迁村并点扶持型40个,面积141.22 hm2,并针对4种农村居民点空间布局优化类型提出较为具体的优化方案。研究结果符合可可以力更镇实际情况,能为农村居民点空间布局优化与整治提供新的思路。     

Effects of different organic materials and mineral nutrients on arbuscular mycorrhizal fungal growth in a Mediterranean saline dryland

Arbuscular mycorrhizal (AM) fungi are root symbionts that enhance plant growth and improve soil fertility and soil structure in drylands. Even though AM fungi are obligate biotrophs, organic matter (OM) can stimulate their growth, but the mechanisms behind this are still unknown. Here, we compared the effect of nutrient patches of different OM sources to intrinsic components of OM such as inorganic nutrient supply and an improved soil water-holding capacity (WHC; via application of hydrophilic polymers), on AM fungal growth. Fatty acids extracted from in-growth mesh bags incubated in the field were used as biomarkers for AM fungi and other soil microbes. We found an enhancement of AM fungal growth in certain nutrient patches. Two out of three OM types stimulated AM fungal growth strongly, and also the addition of inorganic nutrients enhanced AM fungi, though to a lesser extent than OM. Enhanced soil WHC, on the other hand, did not influence AM fungal growth. AMF were more strongly enhanced by the mineral nutrients relative to other soil organisms. Intrinsic nutrients might be an important factor for AMF growth stimulation in OM additions, but there was no evidence that nutrients alone can explain this phenomenon.     

20%氟酰胺可湿性粉剂对草坪褐斑病菌的室内毒力和田间防效

采用菌丝生长速率法进行氟酰胺对草坪褐斑病菌的室内毒力测定,结果表明,氟酰胺对草坪褐斑病菌菌丝生长有很好的抑制作用,EC50为0.014 8mg/kg。田间药效试验结果表明,20%氟酰胺WP 270~375g a.i./hm2对草坪褐斑病有很好的防治效果,防效达84.73%~88.52%。该药剂对草坪草安全,可以广泛用于草坪褐斑病的防治。