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Hu T.,Zhejiang Provincial Key Laboratory of Urban Wetlands and Regional Change | Wu W.,Zhejiang Provincial Key Laboratory of Urban Wetlands and Regional Change | Liu L.,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

This paper has presented a hard and soft classification model that based on hard and soft classification technique to mapping vegetation distributions. It chose SVMs class image as hard classification model and LSMM results as soft classification model. Through a new adaptive threshold algorithm which could define pure and mixed regions of vegetation automatically to combine hard classification results and soft classification results. In the agricultural landscapes of Southeast Beijing City, results from the proposed model were assessed at a range of spatial scales. Results of vegetation distributions were compared with hard classification model and soft classification model with RMSE. Accuracy assessment showed that hard and soft classification model could get better results. © 2014 IEEE.


Qiu J.X.,Zhejiang Agriculture And forestry University | Tang M.P.,Zhejiang Agriculture And forestry University | Tang M.P.,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration | Shen L.F.,Zhejiang Agriculture And forestry University | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Tree diameter structure is an important and basic role in forest structure. For the reason that the diameter at breast height (DBH) can be easily and accurately measured. Because it has a close relationship with variables such as stand density, tree age, tree height, canopy, biodiversity and so on, diameter structure is often used as a direct-response stand structure characteristic. DBH belongs to a set of non-spatial forest structure factors, and is frequently used to analyze the relationship between stand structure and growth, e.g. Recently, studies of forest spatial structure have expanded, partly due to the fact that the DBH is an important factor in explaining the growth of trees, and in many cases because the diameter structure has been used to analyze the relationship between spatial structure and DBH. Similarly, DBH is also an important factor in reflecting the growth of moso bamboo (Phyllpstachys edulis) forests. The DBH of moso bamboo can directly influence leaf area and root area volume, which affects the growth of moso bamboo. Others have performed a number of research studies on the relationship between DBH and other bamboo forest structure factors, such as bamboo height, age composition, canopy structure, and so on. However, these factors are generally measures of non-spatial structure. Recently, research suggests that a distance-dependent spatial index can accurately describe the moso bamboo stand structure, and therefore it is important to analyze and control the relationship between moso bamboo stand structure and function. Previous studies rarely reported the relationship between moso bamboo stand spatial structure and diameter. Therefore, three spatial structure parameters, uniform angle index, neighborhood comparison and age mingling degree were used to analyze the relationship between moso bamboo spatial structure and diameter, and thus provide a theoretical basis for sustainable moso bamboo forest management. The study was established in a close-to nature moso bamboo stand in Tianmu Mountain National Nature Reserve, Zhejiang province. The study design involved a fixed plot of 1hm2(100 m×100 m), which was divided into 100 units by adjacent grid inventory. Each moso bamboo was located in terms of x-, y-, and z-coordinates using a Total Station. Three spatial structure parameters, including neighborhood comparison, uniform angle index, age mingling degree were evaluated. The DBH was recorded into one of three classes: Iclass (DBH < 7 cm), II class (7 cm ≤ DBH < 13 cm), III class (DBH ≥ 13 cm). These classes were used to analyzed the relationship between spatial structure and DBH of the close-to-nature moso bamboo stand. The results showed that the frequency distribution of DBH had a right-skewed normal distribution, which is the similar to even-aged arbor stands. The spatial pattern of class IIand class III was of random distribution, similar to the distribution of the whole stand, but the pattern of class Ishowed an aggregation distribution pattern. The uniform angle indexes decreased with increasing diameter classes, and results showed that the uniform index had a powerful relationship with DBH, with the determination coefficient between DBH and uniform index being 0.7793. The uniform angle of different diameter classes showed no obvious significant difference (P > 0.05). The neighborhood comparison showed that for stands in an intermediate status, the DBH differentiation was not significant. The neighborhood comparison values showed that the ranking of the dominant degree was: III > II > I. And the neighborhood comparisons decreased with increasing diameter classes, as well as had a significantly linear correlation with DBH (the determination coefficient was 0.9233). The neighborhood comparison of different diameter classes showed significant differences (P < 0.01). The average age mingling of the stand was 0.8178, suggesting the age mingling intensity was intensive. The age mingling values showed the ranking of age segregation was: III > II > I. And age mingling increased with increasing diameter classes, as well as had a strong relationship with DBH, where the determination coefficient was 0.6774. The age mingling of different diameter classes was also significanly different (P < 0.01). © 2015, Ecological Society of China. All rights reserved.


Lou M.,Zhejiang Agriculture And forestry University | Tang M.,Zhejiang Agriculture And forestry University | Tang M.,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration | Qiu J.,Zhejiang Agriculture And forestry University | Zhao M.,Management Office
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

Mingling, its concept was put forward by Gadow in 1992, is an important indicator to reflect species mutual segregation in a forest community, and is a significant forest spatial structure index. Currently, many mingling indices have been proposed. A simple mingling index Mg proposed by Gadow only involves the difference between objective trees and their nearest neighbor trees, and cannot accurately reflect the response of tree species to spatial segregation, which was noticed by Tang Mengping(2004) and Hui Gangying(2008). They put forward tree species diversity mingling Mv (further considering the number of nearest tree species) and tree species spatial status Ms (further considering the number of tree species in spatial structure unit), respectively. However, Mv and Ms cannot distinguish the difference between two of the same species on four of the nearest tree species and three of the same species on four of the nearest tree species. Actually, two of the same species on four of the nearest tree species are different in sequence and interleaving arrangement, but they are the same in the analysis of Mv and Ms. Virtually, neighborhood spatial permutation is a significant factor in describing tree species spatial segregation, which was ignored by Mv and Ms. Therefore, a new mingling index, Mp based on neighborhood spatial permutation has been put forward in this paper. "1+4" structure, which was the abbreviation of optimum spatial structure unit proposed by Hui Gangying(2003), composed by one objective tree and four of its nearest trees, and has 17 spatial structure units that are different in tree species spatial permutation. Mp was compared with Mg, Mv and Ms through 17 spatial structure units and evergreen broad-leaved data from Tianmu Mountain, a national nature reserve in Zhejiang province. Data were collected in a 1hm2(100m×100m) permanent plot that had been established in 2005. The results show that Mp has the strongest distinction among them, Mv and Ms are the second, Mg is the worst. The ranking of the different mingling values was: Mg>Mp>Ms, Mg> Mv. Ms and Mp are both able to adequately analyze the simple mixed stand. Mp is the best mingling index among them to analyze the complex mixed stand. Here, there is a high value of mingling, if Mg is used. Sometimes, Mv is unable to analyze the tree species spatial segregation. Spatial structure units which have two of the same species on four of the nearest tree species are different in sequence and interleaving arrangement, and the number of sequence arrangement is significantly more than that of interleaving, and thus there is a moderate mingling level on evergreen broad-leaved in Tianmu Mountain. Mp is based on neighborhood spatial permutation and can distinguish tree species spatial segregation accurately, and has higher distinction degree accuracy than that of traditional mingling. This better reflects the actual mixed situation of forest, and is an effective indicator to reflect species mutual segregation in a forest community. "1+4" structure has17 different spatial structure units, however, what needs further study is the number of spatial structure units in the "1+n" structure, and how to determine the deduction relation. Further, the number of units may obey certain mathematic distributions in natural mixed forests, and the mathematic distribution function may be a significant reference to measure the near-natural degree of cultivation in mixed forests. These issues need further study.


Qiu J.,Zhejiting Agriculture and Forestry University | Tang M.,Zhejiting Agriculture and Forestry University | Tang M.,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration | Lou M.,Zhejiting Agriculture and Forestry University | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016

At present, many individual tree competition indices are used to measure the competitive ability of trees, and they are generally divided into distance-independent indices and distance-dependent indices depending on whether one is considering the space between trees. Distance-dependent indices are commonly used, especially the Hegyi competition index (CH). The CH was used to analyze the spatial structure of a Phyllostachys edulisstand studied by Tanget al., but we found that this CH needs to be improved. P. edulisis a Bambusoideae (Gramineae) species and does not have secondary cambium tissue, resulting in the termination of diameter at breast height (DBH) growth after completion of the stem growth. Unfortunately, there are different competitive intensities associated with the spatial structure of P. edulisstands, even in situations where the same distance exists between object and competition bamboo plants. This means they might have the same DBH, but would be considered to be of a different age. Such distinctions cannot be provided by the existing CH. In fact, competition within a P. edulisstand is affected significantly by intensity of physiological activity, which changes with variation of the metabolic turnover and aging process of an individual, or with its material growth period. Material growth periods are divided into enhancement stages, stationary stages, and declining stages, depending on different intensity of physiological activities. In the light of characteristic of P. edulis, considering its metabolic turnover and aging process, and adding a material growth period factor, a new competition index-competition potential (CP), which is based on CH (the Hegyi model), was proposed to analyze the spatial structure of P. edulisstands. A permanent plot measuring 100 m×100 m, including a relatively lightly disturbed P. edulisstand, was established in the Tianmu Mountain National Nature Reserve, Zhejiang province. There have been five annual surveys of the Plot. Each bamboo tree was tallied and its coordinates (X,Y,Z) were measured using a total station survey device. From 2009 to 2013, we used the new competition index, CP, to quantitatively analyze the dynamic competition within the bamboo stand, as well as to study the dynamic relationship between intensity competition and DBH, and the dynamic relationship between intensity competition and age class. The results showed that the P. edulisstand has clear on-year/off-year cycles and that the competitive intensity of on-years (2010, 2012) is obviously higher than that of off-years (2009, 2011, 2013). The difference in competitive intensity within the P. edulisstand between on-years and off-years was significant (P< 0.01). The difference in competitive intensity within the P. edulisstand between on-years was not significant (P> 0.05), as was the difference in competitive intensity between off-years (2011and 2013;P> 0.05). Because of a snow disaster and the emergence of a number of new shoots, the competitive intensity within theP. edulisstand in 2009 showed significance difference (P< 0.01) from other years. The competitive intensity within the P. edulisstand decreased with increasing objective diameter class, and the results showed that the competition had a powerful relationship with DBH. The competitive intensity within the P. edulisstand increased with increasing age class and also had a significantly linear correlation with DBH.A combination of the growth characteristics and adopted physiological characteristics of P. eduliswas used to develop an expanded analysis of competition between individuals of P. edulis. This allowed us to develop a more comprehensive and effective model (CP) to describe competition within a P. edulisstand. The new CP is therefore a feasible and reliable way to analyze competition within P. edulisstands and their dynamic characteristics. For these reasons, it could provide a theoretical basis for management of artificial P. edulis stands. © 2016, Ecological Society of China. All rights reserved.


Qiu J.X.,Zhejiang Agriculture And forestry University | Tang M.P.,Zhejiang Agriculture And forestry University | Tang M.P.,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration | Shen L.F.,Zhejiang Agriculture And forestry University | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Moso bamboo (Phyllostachys edulis) forests are one of the most economic forests in China, and they possess a lot ofadvantages over other forest types, such as rapid growth, wide distribution, and high production. Traditional moso bamboo stand management involves a predatory management approach which focuses on economic benefits, blind pursuit the production of bamboo and bamboo shoots, and a lack of emphasis regarding the relationship between structure and function. Due to these reasons, this management leads to a series of problems such as soil degradation, increases in plant diseases and insect problems, the inability to withstand natural disasters, and environmentaldegradation. Thus, this suggests that relationship between stand structure and function is a key factor to the sustainable management of these bamboo forests. Traditional descriptions of moso bamboo stand structure have focused on stand-level collective attributes such as density, species composition, and basal area. However, given a general lack of spatial information, non-spatial attributes are difficult to use for accurately estimating whole stand characteristics. The spatial structure of a forest can reflect environmental processes, such as competition, regeneration, spatial distribution, and mortality. These factors can affect the stability,the development, and the management of a stand. Therefore, forest spatial structure approach would involve spatial pattern, mingling, and competition. Information regarding bamboo forest spatial structure is necessary for stand structure optimization. Many static spatial studies have been conducted in bamboo forests, including mingling, spatial pattern, and competition, and so on. Compared with other types of forests, bamboo grows faster, and this provides the possibility to study the dynamic change rule of stand spatial structure. Previous studies had not yet shown the dynamic change of moso bamboo stand spatial structure. Therefore, three spatial structure parameters, uniform angle index, neighborhood comparison, and age mingling degree were used to analyze the moso bamboo stand spatial structure dynamics (change) from 2009 to 2012, and thus provide theoretical basis for sustainable moso bamboo forest management. In July of 2009, one 100 mi×100 m standard plot was established in a close-to-nature Phyllostachys edulis stand in Tianmu Mountain National Nature Reserve, Zhejiang Province. The plot was divided into 100 units by adjacent grid inventory, and has been annually surveyed four times. Results showed that the moso bamboo stand has a clear on-year and off-year cycle, and the average diameter at breast height (dbh) increased gradually over year. The spatial pattern of the stand presents a random distribution in 2009 and 2012, but the 2010 and 2011 years showed an aggregation distribution pattern. The frequency distribution of uniform angle index of each year was described by a left-skewed normal distribution trend, and had no significant difference during these years (P>0.05). The average neighborhood comparison values of each year were close to 0.5, suggesting that the stand has kept an intermediate status. The frequency distribution of neighborhood comparison of each year appeared to have a balanced trend, suggesting that the stand was in a stable state. However, the neighborhood comparison showed no significant difference of each year. The stand showed high age diversity and age isolation levels, and the age mingling value increased as the years increased. The age mingling in the transition period from on-year to off-year was significantly different (P < 0. 05), but in the transition from off-year to on-year there was no significant difference.

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