What can natural edges of gallery forests teach us about woody community performance in sharp ecotones?

Aims The diversity and structure of forest edges are a central issue in ecology.However,most studies have focused on anthropogenic for-est edges,being natural ones least understood.We studied the com-munities of shrubs and trees in natural edges of gallery forests with the main goal of learning what are the main factors that shape the structure and diversity of these natural sharp ecotones.Methods We evaluated 10 gallery forest sites,allocating in each of them three 15×20 m plots.The plots were laid out in relatively rectilinear stretches of forest edges,respecting a minimal distance of 10 m between each plot.As they are permanent plots and meant to study eventual fluctuations in the forest-grasslands limits,we allocated the plots with their longest side parallel to the forest edge and covering perpendicularly 5 m of the grassland and 10 m of forest.Inside the plots we identified,mapped and measured all shrub and tree individuals with diameter at breast height(DBH)≥1 cm.Important Findings Although many differences exist among the communities in terms of density and basal area,all of them were highly dense and had relatively low basal areas.In addition,both the number of individu-als and the basal area increased rapidly towards the forest interior.Our results also revealed that the edge communities are composed mainly by small individuals that demand a great amount of light.Both the vertical stratification and the proportion of the functional groups are similar among the sites yet change quickly in the first 10 m of the forest edge.However,the floristic similarities were low among the communities mainly due to the species turnover within each area.Therefore,although the overall structure is constant in the studied edges,the low floristic similarity among them possibly indicates that the species within the same functional groups are sub-stituting each other across the sites.Despite older and seemingly stable,our results showed the gallery forest edges are quite similar to the anthropogenic edges or recent clearings.This points out that,independent of the age,those characteristics are possibly permanent in edges.

The influence of disturbance on driving carbon stocks and tree dynamics of riparian forests in Cerrado

Aims Riparian forests in the Brazilian Cerrado,also known as gallery forests,are very heterogeneous in structure,species composition and ecological features due to strong and abrupt variations of soil,hydrological and topographic properties.However,what are the variables driving forest carbon stock and productivity,mortality and recruitment in disturbed gallery forests?Methods We used 36 permanent plots data from a gallery forest in the Brazilian Cerrado.We investigated how tree community dynam-ics vary in a gallery forest on two contrasting disturbance levels-logged and non-logged-across a topographic gradient intrinsically related to differences in moisture conditions,edge effects,as well as soil fertility and texture.Important Findings Soil variables were reduced into principal components and we used structural equation modelling to disentangle covarying variables.We also included carbon stocks as a determinant variable of dynamics rates.Logged forest had 50%higher productivity than non-logged forest and streamside forest had aboveground carbon stocks 70%higher than the forest edge.Both logging and natural disturbance drove variation in the carbon stocks which contributed to shaping productivity and recruitment rates.Distance from the river also drove mortality and carbon stock rates.Areas with high-carbon stocks favoured higher competition and lessened produc-tivity and recruitment rates.Although soil fertility and texture are considered crucial components shaping forest dynamics,there was no clear influence of those variables on the present forest,probably because the strong effects of soil moisture,forest edge and distur-bance disrupted the correlation between soil and forest dynamics.

Protection status as determinant of carbon stock drivers in Cerrado sensu stricto

天然植被在全球碳循环和碳储存中扮演着重要角色。巴西大草原塞拉多保护区(Cerrado)因自身固有特性被认为是一个碳汇。本研究的目的是评估具有不同保护状况的三个地区,控制区(法定保护区)、保护区(PA)和非保护区(Non-PA)地上生物量与生物多样性关系的变化。这三个被研究的地区都位于巴西米纳斯吉拉斯州(Minas Gerais)北部。根据森林清查资料,该研究对地上碳储量进行了估算,并测量了每个地区生物多样性指标的三个维度:功能性状优势度、分类学多样性和功能多样性。对物种的以下功能性状进行了评价:木材密度、最大直径和种子大小。通过建立广义线性模型,评估了碳储量、群落加权平均值、物种丰富度和多样性以及功能多样性指数在不同地区间的差异。研究结果表明,未受保护的地区碳储量、物种丰富度、物种多样性、功能丰富度和功能分散度均较低,而保护区和非保护区群落加权平均值最大直径和种子大小均低于法定保护区。广义线性模型结果表明,碳储量与物种和功能丰富度指数在同一地区内和不同地区间存在相关性,因此,物种丰富度可以作为功能丰富度和碳储量的替代指标。物种丰富度和群落加权平均值最大直径对碳储量有正向影响,功能分散度对碳储量有负向影响。功能丰富度、物种多样性和群落加权平均值种子大小出现在最佳模型中,但对碳储量没有显著的直接影响。因此,我们的结论是,在缺乏保护的巴西塞拉多地区会降低物种丰富度和碳储量。

Sharp differentiation on the performance of plant functional groups across natural edges

Aims Gallery forests within grasslands have natural edges with open envi-ronments and offer a unique opportunity to examine how species performances vary across environmental gradients.Here,we asked if demographic rates of tree functional groups varied along the edge,if we could explain differences in plant strategies and performance through functional traits and which traits increase growth and sur-vival in natural edges.Methods We examine mortality and recruitment within the first 10 m of nat-ural edges of eight gallery forests using demographic data from five annual inventories.We defined a priori plant strategies using tree functional groups:light demanding,pioneer and shade tolerant.Important Findings The shade-tolerant group had the lowest mortality rates and basal area(BA)loss,while pioneer and light-demanding species had similar behavior for these rates.The survival and growth of functional groups were affected differently by the distance from the edge.The pioneer group survived more near the edge,while light-demanding and shade-tolerant groups toward the forest interior.All groups had higher growth in the grassland.Those differences could be explained by functional traits since most species have an acquisition strategy:higher specific leaf area and growth,lower leaf dry matter con-tent,lighter stem density,deeper crowns and less slender stems.Acquisitive traits enhanced growth.However,mortality selected both strategies,but in distinct edge’s zones.Our study showed that the high diversity found in natural edges can be explained by a niche and functional perspective,where differences in functional traits lead to differential performance along the environmental gradient.