Differential overstory leaf flushing contributes to the formation of a patchy understory

Understory individuals were found to form patches in a 100-year-old deciduous broad-leaved forest. The closed forest canopy was uniform, and so the light conditions at various locations across the forest floor differed little after the leaf flush of the overstory. To explain the distribution pattern in the understory, a hypothesis was proposed: in spring, the forest floor is divided into patches according to the timing of leaf flush of the overstory individuals, and the light conditions are more favorable for understory plants under the crowns of trees with later-flushing leaves. In the plot, three groups of early, intermediate, and late, were recognized in the overstory concerning the timing of leaf flush. As for the start of leaf flush, a difference of 31.6 days was recognized among tree species, and for the end of leaf flush, a difference of 40.3 days. In the spring of 1998, the relative photosynthetic-photon-flux density under an intensively studiedCastanea crenata tree (late-flushing species) usually showed higher values than that under a similarly studiedAcer mono tree (early-flushing species). Analysis of the spatial-distribution pattern using Morisita’s1δ index revealed that the understory community had an aggregated distribution. In the overstory, the late- and the intermediate-flushing-species groups showed aggregated distributions, while the early-flushing-species group showed random distribution. Spatial correlation between the understory and the overstory was analyzed by using Morisita’sRδ index. The distribution of whole understory community spatially co-occurred with that of the late-flushing-species group of the overstory. In contrast, the understory community was less developed below the members of the early-flushing-species group of the overstory. We consider that the data presented here support our hypothesis, and we suggest that the growth and survival of understory individuals were promoted in the places receiving light for long periods in spring.     

西鄂尔多斯自然保护区沙冬青群落优势种种间关联性

2010年7月在西鄂尔多斯国家级自然保护区运用样方法对沙冬青群落内主要伴生种种群进行样方调查后,运用种间关联性、显著性检验（X2）、关联程度、联接系数等方法进行了分析研究。研究表明：沙冬青群落种间关联性为显著正关联,物种之间关联程度、共同出现概率较高,轻度和高度种间负联接的对数比正联结占优势;群落正在由沙冬青单优种向沙冬青—霸王共优种群落演替。     

纳板河流域林分空间结构的林木竞争探究

林分空间结构一般包括树种混交、林木竞争和林分中林木分布格局等三个方面,对它们一般分别采用竞争指数中的混交度、大小比数及角尺度来进行描述。在纳板河流域不同群落类型林分中设置样地进行调查分析,结果表明,从空间竞争中的混交度方面看,热带雨林、季雨林、季风常绿阔叶林及山地雨林林木主要集中在极强度混交之中,只有少许树种会出现强度混交和中度混交,几乎不出现零度混交和弱度混交,稳定性较高;而落叶阔叶林的稳定性由于样地位置不一而表现较大差距,有较稳定的,也有稳定性较差的。从大小比数看,保护区主要林分内树种大小分化较大,优势程度从优势至劣势都有不均等的分布。各林分的角尺度为0.22～0.34,说明样地林木分布格局为均匀分布。     

大气污染物排放清单空间分配优化探讨——以南京市为例

基于南京市2014～2016年大气污染物排放清单空间分配实践,梳理了影响大气污染物排放清单空间精准分配的因素,探讨了大气污染物排放清单空间分配优化途径及方法。针对空间分配方法优劣、分配原则匹配度、分配参数匹配及提取精准度、技术人员专业度均为影响大气污染物排放清单空间精准分配的重要影响因素,提出了提高空间分配分辨率、提高点源占比率、细化大气污染源分类分级、精确分配大气污染物排放量、优化空间分配参数等优化大气污染物排放清单空间分配的有效途径及办法。     

内蒙古图牧吉国家级自然保护区雁形目鸟类时空分布特征

文章以了解分析内蒙古图牧吉国家级自然保护区雁形目鸟类种类及分布特征并更好地保护管理的目的,于2017年4月至2018年1月份春、夏、秋、冬四个季节,采用样线和样点统计法,对保护区图牧吉泡子和三道泡子两处湖泊湿地雁形目鸟类种类和数量进行调查统计。结果显示:共观察记录到雁形目鸟类22种,隶属于1科8属。图牧吉泡子和三道泡子分别观察到19种和14种。两处湖泊湿地之间距离虽然较近,但雁形目鸟类种类有较大的区别,其中图牧吉泡子不仅种类多,而且珍稀濒危物种的分布也较集中。保护区雁形目鸟类时空分布特征与两处湖泊湿地各自食物资源、隐蔽条件和人为干扰程度有关外也与鸟类本身的迁徙规律和种间竞争有着密切关系。     

Landscape pattern changes over 25 years across a hotspot zone in southern Brazil

Forest fragmentation caused by human activities has many implications for natural landscapes, such as habitat reduction and the loss of biodiversity. This study investigated the temporal fragmentation process of forest remnants in a strongly agro-industrialised region in southern Brazil over 25 years. The studied watershed area hosts two important typologies of the Atlantic Forest biome as well as Quaternary remnants of the Brazilian Savanna biome, which are considered hotspots of biodiversity and reflect the intense process of forest fragmentation caused by Brazilian urban and agro-industrial development. Thus, studies encompassing multitemporal scales are paramount to understanding changes in forest patterns and are fundamental for trend predictions of landscape dynamics. To perform the calculation of the mean normalised difference vegetation index, Landsat satellite images from 1991 to 2016 were processed using SPRING® software. Subsequently, FRAGSTATS® software was used to calculate landscape metrics. A reduction in the number of forest fragments since 1991 was observed, with a maximum amount of 5 243 fragments in 1993 that declined to 4 015 fragments in 2016. Although the number of fragments in the watershed decreased, the mean area increased by 72.9% and the mean of the shape index increased from 1.3 in 1991 to 1.5 in 2016. In addition, there was a 64.7% increase in the edge density and a reduction of 35.6 m in the isolation between the nearest neighbours. The degree of isolation of the fragments underwent a process of expansion and reduction when compared to 1991, presenting results that support the hypothesis that the Atlantic Forest is in a process of stabilisation and forest restoration.     

不同树龄次生甜槠木荷林的树种组成与空间结构比较研究

为了进一步揭示次生甜槠Castanopsis eyrei木荷Schima superba林的林分空间结构特征,在浙江省遂昌县垵口村的20～25年生、35～40年生、55～60年生3个次生甜槠木荷林分别设置了面积为50 m×50 m的样地,进行了每木调查和坐标定位。通过样地Ripley聚集度分析和点Ripley聚集度分析,对3个样地中的优势树种及林分整体的空间格局进行对比分析。结果表明:随着树龄的增加,不同年龄的次生甜槠木荷林的上层乔木立木数量逐渐增加,下层乔木立木数量逐渐减少,树种数量相对稳定,但各层树种组成变化明显,其中上层木中甜槠、木荷、青冈Cyclobalanopsis glauca 3个优势种的比例从20～25年生时的20.41%增长到55～60年生时的73.53%;从空间结构看,20～25年生甜槠木荷林林分呈现聚集分布,35～40年生甜槠木荷林林分呈现半聚集半均匀分布状态,55～60年生甜槠木荷林林分呈现均匀分布。     

金沟岭云冷杉针阔混交林林分结构研究

以吉林汪清金沟岭林场1 hm2云冷杉针阔混交林数据为研究基础,对样地内树种组成、直径结构以及树种的空间分布结构进行分析。结果表明:1)优势物种云杉Abies nephrole-pis、冷杉Picea koraiensis、枫桦Betula costata大径阶的单木占多数,云冷杉的峰度值小于0,直径分布较为分散,枫桦峰度值大于0,直径分布比较集中。在物种的胸径分布格局解释上,负指数模型的解释程度要优于Weibull模型。2)该群落树种的平均角尺度为0.545,空间分布格局呈聚集分布,3种优势树种的平均角尺度为0.475～0.517,呈现随机分布特征。3)云杉、枫桦的平均混交度较高,而冷杉的平均混交度相对较低。4)样地所有物种的平均大小比数为0.496,3种主要树种的平均大小比数排序为云杉<冷杉<枫桦,表明云杉竞争力最大,冷杉次之,而枫桦的竞争力最小。该林分结构较为复杂,群落内树种以聚集分布为主,所以应调整林分林木分布格局,促进林木向随机分布格局发展,同时伐除上层的"霸王树"以及病腐木、弯曲树等处于竞争劣势的林木,将混交度维持在中度混交,从而尽可能保留维持群落的物种多样性。     

森林旅游解说规划中的空间、信息与媒体关系模型构建——以天际岭国家森林公园为例

生态文明建设是中华民族永续发展的千年大计,要促进生态、文化和旅游的相互融合。森林旅游解说作为森林旅游过程中必不可少的传播手段,在我国生态文明建设中发挥着重要的作用。以往的文献中,多从游客角度来研究旅游解说规划,空间视角的相关文献甚少,且研究单一。旅游移动性作为旅游的本质属性,从空间视角认识旅游解说规划中的信息与媒体关系将有助于编制科学的旅游解说规划。以湖南天际岭国家森林公园为例,基于实地访谈法与内容分析法,通过对点-线-功能区-公园-区域等5个空间尺度下的80名游客解说需求与媒体偏好进行研究,构建了森林公园解说规划空间尺度、信息需求与媒体偏好概念模型,具有一定的创新性。研究发现,处于不同空间尺度下的游客对解说信息与媒体偏好存在较大的差异性,并指出游客解说信息需求呈现一定的尺度上升趋势,反之则表现不明显。     

Plant communities, species diversity, richness, and regeneration of a traditionally managed coastal forest, Kenya

The Kenyan coastal forests make up one of the World 25 Biodiversity Hotspots. They consist of over 140 fragments (the majority with areas less than 0.5 km²) of the once extensive Zanzibar-Inhambane lowland moist forest. The over 60 known Mijikenda sacred Kaya forests and groves scattered along the coastal hinterland form the greater part of this ecosystem. The forests are of biological and cultural significance, and this has been recognized nationally and internationally, with some now listed as World Heritage Sites. The forests are protected by councils of Kaya elders who regulate use of their resources. Increasing human population and subsequent rise in demand for forest products and land for settlement has put a strain on these relic forests. Farm encroachment and extraction of forest products in different Kaya forests have affected the vegetation ecology at varying levels. This study investigated the spatial species distribution, association and regeneration potential of commonly utilized plants in one of these traditionally managed ecosystems. A modified nested plot method was used to collect data in the field.Using TWINSPAN multivariate, and indicator species analysis, two plant communities (Asteranthe and Bridelia) and an undifferentiated vegetation type were identified. Species association in Asteranthe consisted largely of forest dependant species, with a significant presence of woody climbers. It was comprised of two sub-communities namely Manilkara and Scorodophloeos. In contrast the second plant community, Bridelia, was dominated by light demanding species. It comprised one sub-community (Catunaregam) and a seral stage (Keetia). The species diversity and richness was higher in the Asteranthe community compared to Bridelia. Some of the forest species commonly utilized by the local people were observed to regenerate both in open and closed forest habitats while others had seedling recruitment confined to closed forest.Despite some coastal forests showing physiognomic similarity, detailed study shows intra-variation linked to topography, exposition, type and intensity of human perturbation both currently and in the distant past. Clearly, vegetation patterns of coastal forests of eastern Africa change at fairly short intervals.Recruitment of forest specialists is likely to decline if closed forests are opened up by farm encroachment, however their less specialized counterparts can pioneer in re-colonization of disturbed sites if conservation is strengthened. There is need to invigorate traditional management systems of forests with cultural significance by recognizing and giving increased legal mandates to the local custodians.