Tradeoffs of nitrogen investment between leaf resorption and photosynthesis across soil fertility in Quercus mongolica seedlings during the hardening period

The most important process before leaf senescence is nutrient resorption,which reduces nutrient loss and maximizes plant fitness during the subsequent growth period.However,plants must retain certain levels of nitrogen(N)in their leaves to maintain carbon assimilation during hardening.The objective of this study was to investigate the tradeoffs in N investment between leaf N resorption and N for photosynthesis in seedlings with increased soil fertility during the hardening period.A field experiment was conducted to determine if and how soil fertility treatments(17,34,or 68 mg N seedling−1)affected N resorption and allocation to the photosynthetic apparatus in Quercus mongolica leaves during the hardening period.Seedlings were sampled at T1(after terminal bud formation),T2(between terminal bud formation and end of the growing period),and T3(at the end of the growing period).Results showed that photosynthetic N content continued to rise in T2,while N resorption started from non-photosynthetic N.Leaf N allocation to the photosynthetic apparatus increased as soil fertility increased,delaying N resorption.Additionally,soil fertility significantly affected N partitioning among different photosynthetic components,maintaining or increasing photosynthetic traits during senescence.This study demonstrates a tradeoff in N investment between resorption and photosynthesis to maintain photosynthetic assimilation capacity during the hardening period,and that soil fertility impacts this balance.Q.mongolica leaves primarily resorbed N from the non-photosynthetic apparatus and invested it in the photosynthetic apparatus,whereas different photosynthetic N component allocations effectively improved this pattern.

Checklist of Polypores on Quercus mongolica in Northeastern China

Poroid Aphylloporales’ growth on Quercus mongolica in Northeastern China wasinvestigated during 1993-2004. The wood of the Mongolian oak seems to be good substratum forpolypores, and 75 species were recorded from the tree or its wood. Out of them 21 species (ca. 28%)are considered as rare species, 30 species (ca. 40%) as occasional species, and 24 species (ca. 32%) ascommon species. Ten species are the pathogens on the Mongolian oak. Most of the polypores werefound on other trees as well, but 14 species live exclusively on Q. mongolica.

Allozymes Genetic Diversity of Quercus mongolica Fisch in China

A gel electrophoresis method was used to study the genetic diversity of 8 Quercus mongolica populations throughout its range in China. Eleven of 21 loci from 13 enzymes assayed were polymorphic. Q. mongolica maintained low level of genetic variation compared with the average Quercus species. At the species level, the mean number of alleles per locus (A) was 1.905, the percentage of polymorphic loci (P) was 52.38%, the observed heterozygosity (Ho) was 0.092 and the expected heterozygosity (He) was 0.099. At the population level, the estimates were A =1.421, P =28.976%, Ho = 0.088, He =0.085. Genetic differentiation (Gst was high among populations, it was 0.107. According to the UPGMA cluster analysis based on the genetic distance, 4 populations located in northeast and 2 populations in southwest of the geographical distribution are classified into 2 subgroups, but there was no clear relationship between genetic distance and geographic distance among populations. The low level of genetic diversity of Q. mongolica might be related to the long-term exploitation as economic tree species in history are comparatively seriously disturbed and damaged by human beings, and most of the existing stands are secondary forests.

Deduction of a meteorological phenology indicator from reconstructed MODIS LST imagery

Phenology is a valuable attribute of vegetation to assess the biological impacts from climate change.A challenge of phenological research is to obtain information on both high temporal resolution and fine spatial scale observations.Here,we constructed an air temperature map based on temporal merging and spatial interpolation algorithms to overcome the cloud-related problem from the MODIS LST product.Then,we derived the accumulated growing degree days(AGDD)from the constructed mean air temperature map to use as a meteorological indicator.Further,we verified the indicator with the seasonal mean air temperature and the green-up date of a Quercus mongolica forest determined from the field-based measurements.The AGDD threshold for each Q.mongolica forest when the first leaf has unfolded was detected from the EXG trajectory extracted from digital camera images.A comparison between meteorological and MODIS-derived AGDD showed good agreement between them.There was also high consistency between DoYs extracted from AGDD and EVI based on curvature K for Q.mongolica forests of 30 sampling sites throughout South Korea.The results prove that microclimatic factors such as elevation,waterbody,and land-use intensity were faithfully reflected in the reconstructed images.Therefore,the results of this study could be applied effectively in areas where microclimatic variation is very severe and for monitoring phenology of undergrowth,which is difficult to detect from reflectance imaging.

不同种源蒙古栎幼苗叶表型性状变异分析

从环境适应的角度去探讨同一生境不同种源的蒙古栎(Quercus mongolica)种质资源的变异规律,为蒙古栎的有效选育和人工造林提供了一定的参考。对来自40个不同种源地的蒙古栎群体叶形态进行观察测定,利用巢式方差分析、相关性分析等分析方法,探讨蒙古栎不同种源间和种源内的叶表型多样性。结果表明,分布广泛的蒙古栎种源间和种源内存在较高的表型变异,且种源间的变异是其表型变异的主要来源,种源间的多样性大于种源内的多样性;随着海拔和纬度的升高,蒙古栎叶片随之逐渐变小,可提高其叶片含水率和比叶面积,适应复杂生境。

不同处理对蒙古栎嫁接成活率和苗木生长的影响

为探索蒙古栎(Quercus mongolica)适宜嫁接方法,本研究开展了不同嫁接方法和IBA处理对蒙古栎嫁接成活率和苗木生长量的影响研究,结果表明:不同试验处理间的嫁接成活率、苗木地径均存在极显著差异,而苗高生长和高径比差异不显著。舌接的嫁接方法为蒙古栎最适嫁接方法。

Exclusion of interspecific competition reduces scatter-hoarding of Siberian chipmunk Tamias sibiricus:A field study

Although food availability and the abundance of seed predators have been postulated to affect seed dispersal,it is not clear how seed-eating animals modify their scatter-hoarding strategies in response to different levels of interspecific competition.We placed paired germinated and ungerminated acorns of Quercus mongolica on 30-cm high platforms to exclude potential interspecific competition of the predominant larder hoarders Apodemus peninsulae and Myodes rufocanus,to investigate seed dispersal by a predominant scatter-hoarder,Tamias sibiricus,in the field in north-eastern China.Our results showed that T.sibiricus ate more acorns in situ in the absence of interspecific competition.In the presence of interspecific competition of A.peninsulae and C.rufocanus,however,more acorns were scatter-hoarded by T.sibiricus.Regardless of interspecific competition,germination of acorns showed no significant effects on seed dispersal patterns,inconsistent with the“seed perishability hypothesis”that animals avoid hoarding seeds with high perishability.Exclusion of interspecific competition,though relatively increasing the per capita seed abundance,appears to reduce seed dispersal,scatter-hoarding and seedling establishment.Therefore,we propose that moderate interspecific competition rather than competition exclusion may benefit seed scatter-hoarding and seedling establishment.

蒙古栎病虫害专家系统的设计与实现

针对目前森林植保专家无法进入现场诊断病虫害,研究开发了蒙古栎(Quercus mongolica)病虫害诊断专家系统,系统收集了蒙古栎主要病虫害的症状特征和图像信息,建立病虫害知识库,将图像指认和症状特征诊断相结合,构建推理机,通过推理诊断出病虫害种类,获得防治方法。

Environmental pressure rather than ongoing hybridization is responsible for an altitudinal cline in the morphologies of two oaks

Aims In a contact zone between related taxa,phenotypic variation can result from genetic and/or environmental gradients.This study aimed to clarify the cause of phenotypic variation in leaf morphology of two Quercus crispula varieties—crispula(QCC)and mongolicoides(QCM)—in their contact zone along an altitudinal gradient.Methods We measured 6 morphological traits of leaves and recorded genotypes of 13 nuclear microsatellite loci for 48 individuals in the contact zone and 24 individuals in each of the reference populations of QCC and QCM.We constructed a model explaining the phenotypic variation(leaf morphology)in relation to environmental(altitude)and genetic(ancestry from the reference population)gradients.Important Findings Both morphological and genetic markers distinguished the two varieties in the reference populations well.We were able to confirm the power of both morphological and genetic markers.Individuals within the contact zone population had intermediate ancestry that was slightly biased to QCM ancestry,and the distribution of their morphologies overlapped with those of the two varieties in the reference populations.The effect of altitude on leaf morphological traits was significant,while that of ancestry was not.Distributions of ancestry and interclass heterozygosity in the contact zone population resembled those in F2 or later generation hybrids.These results indicate that in the contact zone between QCC and QCM,there is no ongoing hybridization,but environmental pressure has created an altitudinal gradient in morphological traits through phenotypic plasticity and/or variation in functional genes.